UNIVERSITY OF CALIFORNIA PUBLICATIONS IN AGRICULTURAL SCIENCES Vol. 1, No. 13, pp. 495-587 March 26, 1917 EXPERIMENTS ON THE EFFECTS OF CON- STITUENTS OF SOLID SMELTER WASTES ON BARLEY GROWTH IN POT CULTURES BY C. B. LIPMAN and W. F. GEEIOKE CONTENTS PAGE .. 496 .. 496 Introduction Objects of the experiments Methods of the experiments - 497 Eesults of the experiments 4" Color of leaves 500 Tillering - 501 Height of plants 503 Germination of seeds 504 Yields obtained 50 ^ Greenhouse soil (copper sulfate) 505 Adobe soil (copper sulfate) - 509 Oakley soil (copper sulfate) 512 Greenhouse soil (zinc sulfate) 514 Greenhouse soil (ferrous sulfate) ^> 17 Greenhouse soil (lead sulfate) 519 Greenhouse soil (potash alum) - 522 Greenhouse soil (manganese sulfate) 525 Greenhouse soil (manganese chloride) 529 Comparison of our results with those of previous investigators 533 Copper sulfate 533 Zinc sulfate 539 Ferrous sulfate 5*1 Lead sulfate 543 Manganese sulfate and manganese chloride 544 496 University of California Publications in Agricultural Sciences [Vol. 1 PAGE Additional investigations 546 Nitrification 546 Nitrogen content of the grain 550 Absorption of metals by soil and plant 551 General and practical considerations 554 Theoretical considerations 558 Summary 559 INTRODUCTION In 1913 1 the senior author and F. H. Wilson reported briefly the results of some preliminary investigations on the effects of CuS0 4 , MnS0 4 , ZnS0 4 , and H 2 S0 4 on the growth of wheat and of vetch in a humus sand in pots, under greenhouse conditions. One year prior to the appearance of the report just cited, the present authors instituted new and more complete experiments with the objects noted below. These experiments, covering a period of three years, are now complete in several significant phases and we are therefore proceeding to a discussion of them. The importance of a study of this subject is attested by the recent appearance of monographic works devoted to it, by the significance of the practical bearings of the physiological studies involved and, in view of these, by the conflicting nature of the results thus far obtained, and the evident non-consideration, by investigators, of the nature of the medium of plant growth as a vital determinant of the results. Some of the outstanding early work on the inorganic poisons, particularly copper, as affecting plant growth is either reviewed or cited in the com- munication above referred to. In this paper no historical sketch will be given, but important investigations which may be rel- evant to our findings will be discussed in connection with the results and meaning of our experiments. OBJECTS OF THE EXPERIMENTS The objects of our experiments were as follows: (1) To ascertain whether metals like copper, zinc, lead, iron, and man- ganese used in the sulfate form in the soil as a medium are toxic in any quantity to barley. (2) To ascertain whether the sub- stances named can be toxic in soils if found in quantities which i Bot. Gaz., vol. 55, no. 6, p. 409, June, 1913. 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 497 would be possible in the vicinity of smelters. (3) To ascertain whether the same substances would be a menace to lands more remote from smelters if carried down to them in solution in irrigation water of streams polluted by solid smelter wastes. (4) To ascertain whether the compounds named may exercise a stinulating effect on plants grown in soil as a medium and, if so, whether the effect noted is ephemeral or permanent in one way or another. (5) To ascertain whether potassium aluminum sulfate can have any value as a source of potash or as a plant stimulant. METHODS OP THE EXPERIMENTS The experiments were carried out in the greenhouse, the successive crops being grown at different seasons of the year so as to allow a study of the effects of a variety of climatic con- ditions. The plants were not artificially shaded during the period of growth. The soil used in most of the experiments was a clay adobe containing a very good supply of organic matter to start witb, and was made up by adding barnyard manure to our hillside clay adobe soil. The other soils employed in a number of the experiments which served as checks on the heavier soils were a blow sand from Oakley, California, and the clay adobe soil above named unmixed with manure. Evidence is thus obtained of the effects on barley of at least one of the salts mentioned, in four types of soils, since a humus sand was, as explained above, employed in the preliminary experiments. The chemical analysis by the Hilgard strong acid digestion method of the humus clay adobe, of the blow sand, and of the clay adobe yielded the results shown in table 1 (p. 498). The containers for the soils just described were ordinary earthenware pots nine inches in diameter at the top. These pots were paraffined to preclude the possibility of the absorption of salts by the porous walls. From ten to twelve pounds of soil were used per pot, depending upon the kind of soil employed. The salts were applied in solution in all cases except in that of the lead sulfate, which, owing to its insolubility, was mixed, in the form of powder, with the soil. The mixing was done as 498 University of California Publications in Agricultural Sciences [Vol. 1 TABLE I Chemical Analyses of Soils Used Greenhouse humus clay Clay Oakley adobe adobe sand Insoluble residue 74.03 85.50 92.04 Soluble silica 9.18 7.40 3.14 Lime (CaO) 2.26 1.05 .66 Iron Oxide (FeS0 3 ) 4.59 3.61 3.60 Aluminum oxide (A1 2 3 ) 5.80 3.85 1.24 Sulfuric acid (S0 3 ) Manganese sesqui-oxide (Mn 3 4 ) .13 .13 Trace Magnesium oxide (MgO) 72 .54 .22 Potash (K 2 0) 62 .25 .30 Soda (Na 2 0) 43 .21 .17 Phosphoric acid (P 2 5 ) 48 .20 .16 Moisture and volatile matter 11.68 4.70 1.72 Total 100.78 100.44 100.32 Nitrogen 31 .12 .03 Humus 3.20 1.85 .30 Nitrogen in humus 6.75 8.00 11.80 thoroughly as possible to approach closely a uniform distribution of the salt. Obviously such thorough mixing as could be desired was not attained with the PbS0 4 ; hence one reason for the irregularity of some of the results obtained therewith. In the case of the copper, lead, manganese and zinc sulfates the treatments were made as parts per million of the dry weight of the soil, whereas the ferrous sulfate was supplied in much larger quan- tities on the percentage basis. The precise quantities of the salts employed are shown in the tables submitted below, but it is added here, in explanation, that the treatments as indicated there represent aggregate amounts in the case of the copper, zinc, iron, and potash alum series of two separate applications, one prior to planting the, first and the other prior to planting the second crop of barley in the humus clay adobe soil. It will further be noted that all the salts were added in the form of sulfates of the metals studied, except as otherwise stated. Water was applied to the surface of the soil in irrigating. As a rule, that operation was carried out twice a week, or as needed, and 400 c.c. of tap water was the amount used at every irrigation. From earlier tests it appeared that this quantity of 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 499 irrigation water and the mode of its application were most desirable under the circumstances and were such as to preclude losses of water and salts by percolation and drainage. Barley (Hordeum vulgar e) was the crop grown throughout all series of experiments. The variety employed was a selected and vigorous strain of Belcli. Three crops were grown in suc- cession on the humus clay adobe soil, the first and third crops being produced in the period between September and January of the years 1912-1913 and 1913-1914 respectively, and the sec- ond crop between March and June, 1913. Only two crops were grown on the non-humus clay adobe soil, in periods correspond ing to the last two for the humus clay adobe soil. One crop only was grown on the blow-sand soil. At the time of harvest, which was carried out when the grain was thoroughly mature, the plants were cut as close as possible to the ground. The total crop thus obtained was placed in paper bags and dried until the weight was constant. Then the weights, separately, of grain and straw were determined. At the same time the soil in the pots was thoroughly worked over to obtain the roots produced in every case. In some instances nitrification .studies on the soil were made, and also determinations of the amounts of salts remaining behind in the soils after harvest, and the amounts taken up by the crop. Enough of these anal- yses, as well as of nitrogen determinations in the grain, were accomplished to ascertain the tendency of these conditions in the plants and soils studied. RESULTS OF THE EXPERIMENTS It will undoubtedly be of interest to our readers to learn first, from the results of our experiments, something of the appear- ance, height, tillering, color, and similar observations on the growth of the barley, and later the yields obtained, composition of the grain, and changes in the soil. The following general statements may therefore be made at this point with respect to the first class of data obtained through the experiments. The different features will be considered separately. 500 University of California Publications in Agricultural Sciences [Vol. 1 Color of Leaves In the first crop on the greenhouse soil the color of the blade was a much deeper green in the treated pots, no matter what salt was used, than in the untreated ones. This was true despite the fact that the leaves were dark green in the plants of the control pots, which had a plentiful supply of available nitrogen at their disposal. The plants of the pots treated with copper sulfate showed, however, a darker green color than those in the pots treated with other salts. That excessive nitrogen feeding was probably the cause of the very deep green color of the leaves referred to was further indicated by the tendency to lodge mani- fested by the plants in the copper and lead series and to some extent in the other series. In the second crop, prior to the plant- ing of which the salt content of all series in the greenhouse soil, except the lead and the manganese, was doubled, manifestations as to color similar to those above described were observed. These were not so marked, however, even though the contrast between the plants on the treated and those on the untreated soils was easily discernible. As a result of the smaller amount of stimula- tion in the crop under consideration, no tendency to lodging was noted, and the plants were erect and rigid. In the third crop on the same soil without further salt treatment, there was only a slightly deeper green color in the leaves of plants on the treated than in those on the untreated soil. Again, the plants were erect and vigorous in appearance throughout. On the Oakley blow-sand soil, in which only copper was tested, was discerned a similarly striking effect on the color of the barley blade exercised by the salt treatment of the soil. In the clay adobe soil similar observations were made. We are therefore led to believe that the effect of the salts in question seems to be general in at least one direction for all soils, namely, for the production of a deeper green color in the leaves of plants growing on the treated soil. The stimulating effect in that direction shows a tendency to diminish at first rapidly, then slowly, in the succeeding crops. The probable causes of this manifestation, as briefly referred to above, will be mentioned later in connection with the studies of the treated soils them- 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 501 selves. As further evidence of the general nature of the effects of the salts in question in soils on the color of the leaves of plants, we may cite again the observations on that point made by both Pammel 2 and Van Slyke. 3 Those investigators reported marked deepening of the color of the leaves of tomatoes and other plants due to treatment of the culture soil with CuS0 4 . Other kinds of plants, therefore, as well as other soil types than those employed by us seem to be similarly influenced by CuS0 4 with reference to color production in leaves. Tillering During the first two crops grown, the amount of tillering occurring in the plants on the greenhouse soil was studied. This was done with the idea of noting if any close correlation existed between the amount of growth and dry matter produced by the treatment and the number of tillers formed. Our observations give a negative reply to this query. Thus in the first crop of the copper series the number of tillers per pot of four plants varied from thirteen to thirty-one over the whole range of concentra- tions of copper sulfate employed. This in itself would of course be of little significance in connection with the question under consideration if there was a decrease or an increase in the number of tillers with a change in concentration of CuS0 4 . This was not strictly the case, however, and to illustrate we may say that the largest number of tillers in the first crop of the CuS0 4 series was in one of the pots receiving 1500 p. p. m. CuS0 4 ; the smallest number of tillers was produced in the pots remain- ing untreated. Moreover, there was but little agreement in that respect between duplicate pots receiving CuS0 4 . Thus the duplicate of the pot above mentioned as producing the largest number of tillers (thirty-one) produced only twenty-one, and such large discrepancies between duplicate pots were common. The fact remains, nevertheless, that while small concentrations and large concentrations of CuS0 4 do not differ in their effects on the number of tillers, some CuS0 4 as against no CuS0 4 ap- pears to be of definite effect in the first crop. Thus in the large 2 Iowa Agr. Exp. Sta. Bull. no. 16, 1892. sN. Y. (Geneva) Agr. Exp. Sta. Bull. no. 41, 1892. 502 University of California Publications in Agricultural Sciences [Vol. 1 range of concentrations employed in the copper series, there was no pot receiving CnS0 4 in any quantity which did not produce more tillers than any of the control pots, which showed from thirteen to fourteen tillers in each of three pots employed as untreated controls. In general, therefore, it seems that in the first crop, copper sulfate does stimulate tillering, but it does so irregularly and small amounts of the salt appear to be as effect- ive in that direction as large amounts. In the second crop of the CuS0 4 series the number of tillers was decreased throughout because of climate and other obvious effects accompanying the conditions of the experiment which are above described. Never- theless, the treated pots were, with very few exceptions, decidedly superior in tiller production to the untreated pots, which, again, agreed well among themselves. Otherwise, the tillering of the second crop in the CuS0 4 series was not significantly different from that of the first crop. In the first crop of the zinc sulfate series the number of tillers was very markedly larger than in the first crop of the copper sulfate series. Thus the largest number of tillers pro- duced in the first crop of the copper series is about equivalent to the smallest number of tillers in the first crop of the zinc sulfate series. In one pot of the zinc series sixty-five tillers were produced by four plants, a number more than twice as great as the maximum in the first crop of the copper series. Moreover, the agreement between duplicate pots was on the whole much better in this regard in the zinc than in the copper series, despite the fact that several large discrepancies were noted. In the first crop, therefore, the zinc sulfate, like copper sulfate, has not only stimulated tiller production, but has done so to a much more marked degree than the last-named substance. In the second crop, however, conditions and results are considerably changed. Thus, whereas the stimulating effects of CuS0 4 on tiller production are clearly manifest throughout the series, even after the salt concentration is doubled in the same soil, only one case of stimulation in that respect (at the lowest con- centration) is noted in the ZnS0 4 series under similar conditions. Moreover, in the CuS0 4 series we find scarcely one undoubted case of depression in tillering even in the second crop, due to 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 503 the treatment of the soil, but such depression obtains almost without exception in the second crop of the ZnS0 4 series. In other words, a very marked decrease in the number of tillers results from the second ZnS0 4 application to the greenhouse soil, both absolutely and relatively speaking, in comparison with either the untreated control pots or with the treated pots of the copper series. Much better agreement between duplicate pots with reference to tillering is noted in the second crop of the ZnS0 4 series than in the other series above described. In the case of the potash alum series, in the first crop the results were very similar to those obtained in the corresponding copper series except that tillering was not so markedly stimu- lated as in the latter. In the second crop, also, the results of the potash alum series were not strikingly different as regards tillering from those in the copper series. In the first crop of the FeS0 4 and PbS0 4 series no observa- tions were made on tillering owing to the poor development of plants and their prostrate mode of growth, which was especially marked in the lead series. Observations on the amount of tiller- ing produced in the second crop of the FeS0 4 series indicated that the stimulating effect of the FeS0 4 on tillering was not so great as that of either copper or potash alum, but greater than that of zinc. In the third crops of all series scarcely any tillering was observed, the plants producing for the most part single upright stalks. It appears, therefore, that the stimulating effects of the salts tested with respect to tillering are ephemeral in their nature, but are more distinctly so with some salts than with others. Height of Plants In the second crop only, observations and measurements were made of the average and total heights of plants produced in the CuS0 4 , ZnS0 4 , FeS0 4 , and potash alum series. These indicated definite increases in height of plants produced by certain concen- trations of all the salts named, over those attained by the plants in the untreated pots. The superior height of the plants was, however, variously distributed through the series. Thus it was 504 University of California Public-alums in Agricultural Sciences [Vol. 1 apparent in the first five lowest concentrations of the CuS0 4 series. It did not show in the first two concentrations of ZnS0 4 . but in all others, and was clearly manifest almost throughout the potash alum series. In the FeS0 4 series the heights followed the general observations just recorded for the ZnS0 4 series so far as comparison with controls is concerned. As regards abso- lute heights of plants the ZnS0 4 series showed the highest, and the potash alum series was a close second, with the others con- siderably behind. It appears, therefore, that with regard to stimulation both of tillering and of tallness, ZnSO, is superior to the other salts. The agreement between duplicate pots in respecl to the height of plants was far more satisfactory than that for tillering. None of the actual data are given here because of the necessity for brevity in such papers and because of the decidedly minor sig- nificance of the results in connection with the main issue under examination. Germination of Seeds In all of the series under discussion, the germination of seeds was more rapid in the sail treated soils than in those untreated, at least up to certain very considerable concentrations of the salts. Exceptions to this rule were of course found in certain concentrations of the salts which entirely inhibited growth and in those which almost did so; but in all pots in which the salt concentrations were not of that older, germination was much more rapid than in those which remained untreated. The stimu- lation in respect to germination was about of the same degree in all concentrations of every salt which would at all stimulate germination, larger amounts of sails not differing from the smaller ones. Certain definite differences, however, existed in that regard among the different salts. Thus CuS0 4 stimulated germination most, ZnS0 4 was second in order, FeSO, third, and the other salts exerted only a slight influence. Our findings in this respect, therefore, are again in accord with those of Pam- mel 4 and Van Slyke, 5 which are above cited, and also with * Iowa Agr. Exp. Sta. Bull. no. 16, 1892. 5N, Y. (Geneva) Agr. Exp. Sta. Bull. no. 41, 1892. 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 505 those of many other investigators, among- whom may be men- tioned Effront. 6 It may be added here that the stimulating- effects of the salts studied with respect to germination of seed were noted in the first and second crops. In the third crop there was little, if any, superiority in germination of the seeds in the treated as against the untreated pots. In other words, we have noted that in regard to germination, as well as in respect to tiller- ing and other superficial characters, the salts employed stimulated the barley for one or two seasons at certain concentrations and after that showed no marked effect in either direction. It should also be observed that in cases in which such salts as CuS0 4 at higher concentrations retarded germination in the first crop, the retarding effect disappeared in the second and third crops. YIELDS OBTAINED In studying the yields of barley in all the series, the weights of straw, of grain, and of roots were determined in every case after drying at 100° C and bringing to constant weight. All such determinations are given in the tables which follow, to- gether with other necessary data. It will be noted that the yields of the single pots in every duplicate pair are given, as well as the averages. This is for the purpose of pointing out the large variations in yield frequently obtained in duplicate pots of soil cultures and for that of allowing our colleagues to study our data at first hand and reach their own conclusions. The different salts will be considered separately below, with one type of soil at a time. Copper Sulfate — Greenhouse Soil Tables II«, II b, and lie give the results obtained with CuS0 4 in three successive crops on the greenhouse soil. Through an error, as was stated above, a second application of CuS0 4 equiva- lent to the first was made to the soil prior to planting the second crop, so that for the second and third crops, amounts of CuS0 4 were present in the soil which were far larger than those intended for the study. While, therefore, we have obtained Effront, J., Comptes Rendus Acad. Sci. (Paris), vol. 141, p. 625, 1905. 506 University of California Publications in Agricultural Sciences [Vol. 1 three successive crops on the same soil, only one of them, the third, was influenced purely by the residual effects of the CuS0 4 application remaining after the production of one crop. With these observations in mind, let us now consider the results of the CuS0 4 applications in the three crops harvested on the greenhouse soil. First Orop The growth of the plants in the first crop was very rank in the controls as well as in the treated pots, with the result that high yields of dry matter were obtained. This was doubtless due to a large supply of available plant food in the fresh greenhouse soil and especially to the high nitrate content and high nitrify- ing power of the soil. The deep green color of the leaves, above referred to and the tendency shown by the plants to lodge seem to confirm this view, and it is further supported by nitrification studies which we carried out and which are reported below. Because of the conditions for rank growth, however, tin- growing season was lengthened and scarcely any grain was pro- duced. The data of the first section of table II therefore give only the yields of straw and roots. Despite considerable dis- crepancy among the yields of duplicate pots, there can be no question after an examination of the data for the firsl crop that CuS0 4 , in the i titrations and tinder the conditions employed, has caused the barley to produce more dry matter than was pro- duced in the control pots. Such stimulated growth is apparent throughout the whole series of copper concentrations varying from 50 p. p. m. to 1500 p. p. m. Concentrations above 1000 p. p. m. seem to be definitely more toxic, or at least less stimulating, to the barley plants than lower concentrations if average yields are adopted as criteria. Such procedure may, however, be unjusti- fiable because of the large discrepancies among the yields of duplicate pots. That the increases in yields of dry matter of barley are real and not accidental is evidenced not only by their manifestation in the whole series, but also by the magnitude of the increases involved. Thus in the concentration of 600 p. p. m. CuS0 4 an increase in yield over that of the control pot was obtained which was equivalent to nearly 50 per cent of the total 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 507 yield of the latter, and in several other cases such increases amounted to 30 per cent or 35 per cent. Giving brief consideration now to the yields of roots alone, we find that they, too, like the total dry matter in general, are definitely affected by the CuS0 4 treatment. Increased root pro- duction over that in the control pots is found in all the pots having concentrations from 50 p. p. m. to 600 p. p. m. CuS0 4 , inclusive. Beyond that point, however, unlike the case of the total dry matter considered, the increased concentrations of CuS0 4 appear to depress root development very definitely. The decreases continue steadily more significant as the concentration of CuS0 4 increases from 600 p. p. m. to 1100 p. p. m., when the toxic effect seems to reach a stationary point and no further decreases occur, even though more CuS0 4 is added up to concentrations of 1500 p. p. m. Taking into consideration the effects of CuS0 4 on the first crop of barley in the greenhouse soil in regard to both tops and roots produced, it appears that we must consider the point of stimulation to cease at 600 p. p. m. CuS0 4 . It is possible in addition that even the 700 and 800 p. p. m. concentrations may be looked upon as still stimulating to both tops and roots of the barley plant in the soil in question. Beyond those points, however, CuS0 4 is stimulating, in the first crop, to the produc- tion of tops only, not to the production of roots. Second Crop The very large decrease in yield of the second crop in the same pots, so far as total dry matter is concerned, is clearly indicated in table lib. This is evidently not due to the doubling of the percentage of CuS0 4 in pots receiving treatment, since the decrease in the second as compared with the first crop is just as clearly marked in the control pots. On the other hand, whereas the first crop produced practically no grain, probably for reasons above discussed, the second crop produced a large yield of grain, amounting not infrequently to 25 per cent or considerably more of the total dry matter. Again, we see in the figures for the second crop the disparity between yields of duplicates, but again also the consistently large yields of dry 508 University of California Publications in Agricultural Sciences [Vol. 1 matter in the treated as against those of the untreated pots. This is strikingly so for both the straw and the grain yield, but is most consistently and undeniably apparent in the latter. The root yields in most of the treated pots are also superior to those obtained in the untreated pots, and duplicate cultures show better agreement in that respect than do the straw and the grain yields. The grain produced was in all cases well filled and normal in appearance. In brief, we find that the second crop on the soil treated with CuS0 4 , despite the doubling of the CuS0 4 application, shows as markedly, and perhaps even more markedly, the stimulating effect of the salt under consideration to barley grown on greenhouse soil. While in detail the results of the second crop differ from those of the first crop, they appear to confirm the latter in general. The average yields of dry matter are greater with all treatments than they arc in the untreated pots. This strikingly stimulating effect of CuS0 4 on barley under the conditions named in concentrations reaching a maximum of 0.3 per cent CuS0 4 , based on the dry weight of the soil, is as astounding as it is interesting, and it would appear to lend little support to the idea of the toxicity of CuS0 4 in relatively small amounts to crops grown on field soils. This phase of the subject will, however, receive more attention below. Third Crop Grown under more propitious weather conditions, as ex- plained above, the third crop in the CuS0 4 series on the green- house soil yielded throughout ninch larger amounts of dry matter than the second crop, though not snch large amounts as the first crop. Again, we note the general stimulating effect of CuSO, to the production of dry matter in barley plants. This time, it should he observed, the stimulating effect was not mani- fest throughout the treated portion of the series, as it was in the first two crops. Thus four of the CuSO, concentrations employed, namely, 600 p. p. m., 1600 p. p. m., 2400 p. p. m., and 2600 p. p. in., depressed the yield of barley if average yields of duplicate pots are considered. In most cases, however, such depression of yield is easily within the experimental error and therefore may be without significance. This is especially so 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 509 since there is no regularity in the inhibiting- power of CuS0 4 referred to ; but small as well as large concentrations at isolated points in the series depressed the yields as above pointed out, whereas the rest of the concentrations, also small and large, stimulated the yields. While the total dry matter produced in the third crop, as shown above, is greater than that yielded in the second crop, the yield of grain in the latter is far superior to that in the third crop. Thus the highest grain yield in the third crop is scarcely more than one-third that of the second crop, and the lowest yield of the third crop is about one-sixth that of the second crop. Nevertheless these facts are of no significance in connection with the effects of CuS0 4 , since the control pots manifest the same depression in grain yields which is character- istic of the treated pots in the third crop. Likewise, in most cases the treated pots produced more grain than the untreated pots. The point of maximum stimulation of CuS0 4 to the produc- tion of dry matter by the barley plant on the greenhouse soil is very difficult to discern. While apparently it occurs at the concentration of from 0.18' per cent to 0.2 per cent CuS0 4 of the dry weight of the soil, the irregularity and non-agreement of many of the duplicate pots render decisions in such matters unsafe, if not valueless. In general, however, the figures in table lie leave little room to doubt the non-injurious nature and perhaps the stimulating effect of CuS0 4 , at considerable con- centrations, for barley in the greenhouse soil under the conditions described. Copper Sulfate — Adobe Soil Tables Ilia and b give the results obtained with CuS0 4 treatment in the case of the adobe soil in the first and second crops respectively. It will be noted at the outset that the yields on the adobe soil are much lighter than those on the greenhouse soil. The reasons for this circumstance are of course not far to seek, in the light of the origin and descriptions of the soils used in these experiments which are given above. Only two crops were grown on the adobe soil, because we did not decide 510 University of California Publications in Agricultural Sciences [Vol. 1 to start it for comparison with the greenhouse soil until one crop had been obtained with the latter. First Crop We find in the case of the adobe soil the same unfortunate disparity among the yields of duplicate pots which was noted with the greenhouse soil. This disparity is of course the more noticeable when much smaller absolute amounts are involved, as in the present case. Despite all that, however, there appears to be justification for the conclusion, based on the data in table Ilia, that CuS0 4 does exercise a stimulating action on the growth of barley in adobe soil. Such stimulation is not apparent throughout the whole series, as it is in the ease of the green- house soil, but it appears to exist in all concentrations of CuS0 4 employed up to 900 p. p. m. Concentrations in excess of the latter seem to depress, definitely, the yield on the adobe soil. But whether or not we admit the existence of a stimulating effect by CuS0 4 on the barley, based on the figures here studied, it can scarcely be denied that CuS0 4 is not toxic to barley in the first crop grown on adobe soil until nearly 0.1 per cent CuS0 4 is present in the soil. Amounts of CuSO, slightly less than 0.1 per cent stimulate the growth of the barley significantly. At concentrations of 0.15 per cent and 0.2 per cent CuS0 4 no growth is obtained at all, showing of course marked toxicity. Some interesting facts are brought to light in table lib/ with respect to the relationships among straw, grain, and root yields which obtain between treated and untreated soils and among themselves in the case of the different concent rations of the latter. In the first place, it will be noted thai the grain yields form an even larger percentage of the total dry matter of the first crop on the adobe soil than they do in the second crop on the greenhouse soil. In some cases, indeed, the average yield of grain in duplicate pots exceeded the average yield of straw. In nearly half the treatments, the grain yields were larger than those of the control pots so that the stimulating effect of the CuS0 4 application, if allowed, applies to the grain yields as well as to those of total dry matter. The root yields are pro- 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 511 portionately smaller on the adobe than on the greenhouse soil, as are the yields of the barley as to tops. Nevertheless, the aver- age yields of roots also show the stimulating effects of CuS0 4 , since they are greater in all concentrations than those of the control pots until a concentration of 1000 p. p. m. CuS0 4 , or 0.1 per cent based on the dry weight of the soil, is reached. In excess of that concentration, CuS0 4 is toxic to roots and appears to inhibit their development. Second Crop Much better agreement among the yields of straw in dupli- cate pots of the second crop on the adobe soil was obtained than in any of the series with CuS0 4 above described. In fact, the agreement between the duplicates in nearly all cases was as good as could possibly be hoped for when one allows for the ever-present idiosyncrasies of plant protoplasm. Up to and including concentrations of 400 p. p. m., CuS0 4 seemed to depress barley growth except in one concentration, namely, at 300 p. p. m. Such depression is probably not significant, except at the concentration of 100 p. p. m. However that may be, CuS0 4 did not stimulate the development of barley at the lower concentrations in the second crop on the adobe soil as it did, with one exception, in the first crop. On the contrary, conditions reversed themselves in the second crop, and the most marked and consistent stimulation occurred in the higher con- centrations of CuS0 4 , only the very highest concentration — namely, 2000 p. p. m. — showing a more or less definitely toxic effect. Thus, while no growth was obtained in the first crop on the adobe soil containing 1500 p. p. m. of CuS0 4 , the same soil on the second planting stimulated the growth of barley so that in both pots, taken separately and by averages, the yield was superior to that of the control pots. Irregularities of course crept into this series as into the others, for instance, depressed growth or no stimulation at a concentration of 1200 p. p. m., when stimulated growth is obtained at 100 p. p. m. CuS0 4 on the one hand and at 1500 p. p. m. on the other, is a circumstance which is very difficult of explanation. ol2 University of California Publications in Agricultural Sciences [Vol. 1 Again, unlike the first crop on the adobe soil, the second crop yielded no grain. This of course cannot be attributed in any way to the effects of CuS0 4 , since the control pots behaved in the respect noted like the treated ones. Presumably, unfavor- able climatic conditions and the heavy nature of the soil may have produced and influenced the result obtained. The root yields, however, were very considerably larger in the second than in the first crop, and fairly good agreement between dupli- cate determinations was obtained. Considering the small total yield of dry matter in roots, it is perhaps a very significant stimulation to their development which CuS0 4 exerts. Regarded then from the standpoint of the total dry matter produced, there appears to be no question from the data in table III5 that CuS0 4 can stimulate growth in the barley plant on a clay adobe soil even when present at very considerable concentrations. If only the dry matter of the above-ground parts is considered, three exceptions to this rule in the whole series can be found. In a general way, the results with CuS0 4 on the adobe soil confirm those obtained on the greenhouse soil using the same salt. It may be repeated with advantage here that even if such stimulating properties of CuS0 4 , which in our opinion we have shown above to exist, arc not allowed, our data do not offer any support to the idea that in the ordinary quan- tities in which copper may be introduced in agricultural soils it is even likely to be toxic to grain plants. Copper Sulfate — Oakley Soil Only one crop of barley was grown on the Oakley soil in the tests with CuS0 4 . Since closing the experiment we have regretted the fact that the Oakley soil was not cropped succes- sively for two or three seasons after treatment, but at the time of the experiment this was not deemed necessary. Table IV gives the results obtained with the one crop in question. The figures really do not tell the whole story, since the appearance of the barley plants was far superior on the treated soils on which they developed at all than it was on the untreated soil. Nevertheless, the figures are striking enough to be used alone 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 513 as a criterion to determine the effects of CuS0 4 on the growth of barley in the Oakley sand. Onr data show very clearly the stimulating effect of CuS0 4 for barley in the first crop on the Oakley sand. They also show, more clearly than any series above described, the toxic effect exercised by CuS0 4 at the higher concentrations. The stimulating effects further do not occur at such high concentrations of CuS0 4 in the case of the Oakley sand as in that of the greenhouse soil or even in that of the adobe soil. To be specific, we find that at concentrations of 100, 200, and 300 p. p. m., CuS0 4 is definitely stimulating to barley production on the Oakley soil under the conditions of our ex- periment. The most marked results of the stimulation in ques- tion are not manifest in the production of straw or even in that of roots when it is at all perceptible, but is very marked in nearly all cases so far as grain production is concerned. It is a curious fact that at a concentration of 600 p. p. m. CuSO + in the Oakley soil, we obtain the largest grain production of the whole series, and yet the straw production is depressed through the CuS0 4 treatment at that concentration and the root development almost entirely inhibited. This fact is very difficult to explain, but exhibits parallelism to similar facts observed by both Pammel and Van Slyke in the experiments above cited. When the dry matter produced is considered as a whole, and straw, grain, and roots are considered together, stimulation is noted only in the case of the first two concentrations of CuS0 4 employed, and the stimulation is not very marked. In other words, one is obliged to state definitely the criterion employed when forming a judg- ment as to the existence or non-existence of a stimulating effect of CuS0 4 on barley grown on the Oakley sand. It will be necessary in the future, for a more decided judgment of the question in hand, to grow several successive crops of barley on the soil named, once treated with CuS0 4 , as shown in the table, and possibly also to supply available nitrogen, which is a serious limiting factor in the growth of barley on that soil. Without making any final statements in the premises, however, the data given by us in table IV seem to point strongly to the existence of a stimulating action of CuS0 4 to barley growth, even on the Oakley sand. 514 University of California Publications in Agricultural Sciences [Vol. 1 Zinc Sulfate — Greenhouse Soil Only the greenhouse soil was employed to test the effect of ZnS0 4 on barley plants. As was the case with CuS0 4 on the same soil, three successive crops were grown, two treatments of ZnS0 4 being given. The results obtained, together with the treatments given, are indicated in tables Ya, Yb, and Yc. First Ceop A study of table Ya reveals the fact that ZnS0 4 in the case of the first crop of barley is not unlike CuS0 4 in its action. In other words, while the latter salt exercises a greater and more definite stimulating action in the first crop, ZnS0 4 also manifests a definite though smaller stimulating effect on the barley plants. This seems to be supported by the fact that only eight pots out of thirty treated with varying amounts of ZnS0 4 give a smaller yield than the highest yield of the control pots. In general, the stimulation seems to be greatest at concentrations of ZnS0 4 varying from 500 p. p. m. to 1200 p. p. m. inclusive. This state- ment has reference only to the total yield of dry matter and not to any parts, like roots or tops, taken separately. On the same bases, also, no definitely toxic effect of ZnS0 4 was observed, though, as above intimated, some apparent effects of that nature were noted. Again, in accord with the results obtained with CuS0 4 no grain worth weighing was produced in the first crop, and the weights of the straw given in the table therefore include such partially formed heads as were developed. In still further agreement with the results of the first crop of the CuS0 4 series, ZnS0 4 stimulated the growth and develop- ment of roots practically throughout the whole series. The stimulation to root development alone was, however, greater in the ZnS0 4 series than in the CuSO, series, just as the opposite was true for the tops. The greatest stimulation to root develop- ment appears to have been attained at the higher rather than at the lower concentrations of ZnS0 4 , the difference being most marked in that respect between the first three concentrations employed and the rest. This circumstance, as will be seen by a comparison of table Ya with table Ha, is the reverse of that noted in the first crop of the CuS0 4 series, in which the first four 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 515 concentrations gave the largest increases of dry matter of roots over the controls. All in all, the effect of ZnS0 4 in the case of the first crop on the greenhouse soil must be regarded as one definitely stimulating to the production of dry matter in the barley plant. Second Crop While in the first crop the CuS0 4 and ZnS0 4 series are in general similar so far as the effects of the salts on the barley plants are concerned, they differ markedly in the second crop. To illustrate, it may first be noted in table Yb herewith, on the basis of the total dry matter produced, that ZnS0 4 beyond con- centrations of 600 p. p. m. is distinctly toxic to barley in the greenhouse soil. With similar concentrations of CuS0 4 in the second crop, the latter salt was not only not toxic beyond 600 p. p. m., but was aetiially more stimulating at most of the higher than at the lower concentrations. It would therefore seem that so far as the yields of the total dry matter are concerned, ZuS0 4 is either more toxic than CuS0 4 or the latter is more readily adsorbed by the greenhouse soil and thus removed from the active solution which bathes the feeding roots. It must, never- theless, be added that while ZnS0 4 appears to be definitely more toxic to barley than CuS0 4 in the greenhouse soil, it cannot be considered very toxic since 0.06 per cent ZnS0 4 of the dry weight of the soil is not only not toxic, but actually stimulating. We may now consider for a moment the different components of the total dry matter produced in the second crop of the ZnS0 4 series. So far as the straw alone is concerned, only a concentration of 200 p. p. m. ZnS0 4 gave stimulating effects. That concentration produced a very marked stimulation, and good agreement is evident in the duplicate pots. Concentrations in excess of 200 p. p. m. depress straw production. Such depression, however, is in some instances not very great, and considerable disagree- ment between duplicates here, as in the copper series, renders it difficult to pass final judgment in the matter. In general, there is little difference in the depressing effects on straw pro- duction of concentrations of ZnS0 4 varying between 600 p. p. m. and 3000 p. p. m. Beyond 3000 p. p. m. a more definite depress- 516 University of California Publications in Agricultural Sciences [Vol. 1 ing effect on the production of straw in the second crop becomes apparent. The fact that the wide range of concentrations just referred to is productive of similar effects seems to indicate that most of ZnS0 4 is adsorbed by the soil and but little of it is free to affect the plant in the soil solution. With the exception of one or two doubtful cases, grain production is somewhat depressed throughout the second crop of the ZnS0 4 series. This appears to be even more true for the first concentration of ZnS0 4 , which stimulates straw production, than for the higher concentrations, which depress straw pro- duction. All of these judgments, however, are based on averages of duplicate pots which do not agree very well, and hence con- siderable caution is employed in stating them. Again, the effect of ZnS0 4 on grain production seems to be about the same whether small or large quantities of the salt are employed. So far as root production is concerned, however, the data of the second crop in the ZnS0 4 series are very different from those bearing on the yields of grain and straw. With three exceptions, two of them at the highest concentrations of ZnS0 4 employed, the latter induced the production in all pots of more roots than were produced in the control pots. While in many eases the stimulation in the direction noted was not great, it was definite, and in many other cases it was very considerable. Moreover, there was good agreement between the duplicate de- terminations. The greatest stimulation to root production occurred between 200 and 2600 p. p. m. ZnS0 4 . While, there- fore, the second crop of the ZnS0 4 series differed from that of the CuS0 4 series with respect to grain production, there was great similarity in action between the two as regards root yields. Third Crop In the third crop of the ZnS0 4 series, the toxicity of ZnS0 4 appears to have become augmented even over that of the second crop. There seems to be no case of stimulation even in the lowest concentration (200 p. p.m.). This applies to straw, grain, and roots equally well. On the other hand, the toxicity of ZnS0 4 for root and grain production by barley in the third crop is certainly not very marked, although uniform. For straw 1917] Lipman-Gerickc : Smelter Wastes and Barley Growth 517 production, ZnS0 4 becomes suddenly very much more toxic than at the lower concentrations when more than 2400 p. p. m. is employed in the culture medium here used. At 200 p. p. m. neither the straw and grain on the one hand, nor the roots on the other, are seriously affected in one direction or another by the ZnS0 4 in the third crop. Beyond these remarks no dis- cussion of table Vc is necessary. The figures given in that table speak plainly enough for themselves. In contrast with the CuS0 4 series of the third crop, however, table Vc shows ZnS0 4 to be again totally different in its effect on the barley plant in the greenhouse soil. Thus the CuS0 4 exercises a stimu- lating effect on total dry-matter production in the third crop at almost all concentrations, while ZnS0 4 , far from doing so in any case, is actually toxic in all concentrations in the third crop on the same soil. This points clearly to sharp differences in the specific physiological effects of the copper and zinc ions, since they were the only apparent variables in question in this experiment. Ferrous Sulfate — Greenhouse Soil Owing to the rapidity with which ferrous salts are rendered insoluble in well-aerated soils, it was deemed advisable to depart from the procedure followed in the other series so far as quan- tity of FeS0 4 used is concerned. Applications of the salt were therefore made at intervals of 0.1 per cent between two suc- ceeding cultures in the series, the lowest concentration used in the first crop being 0.1 per cent, and the highest 1 per cent. As in the other series above described on the greenhouse soil (the only one used in the FeS0 4 series), the amounts of salts were doubled prior to planting the second crop. The results of the yields are given in tables Via, Ylb, and Vic. First Crop Even though the amounts of FeS0 4 used were very large, we see clearly from table Via that the salt stimulated, in the first crop, the production of dry matter in barley. Considering averages of duplicate pots, we find that there is no concentration 518 University of California Publications in Agricultural Sciences [Vol. 1 of FeS0 4 which did not yield increased growth of barley. This constitutes the most striking set of stimulations noted in the series thus far discussed. Moreover, we find again an evident lack of relationship between the amount of FeS0 4 employed and the degree of stimulation induced thereby. In agreement with the results obtained in the CuS0 4 and ZnS0 4 series, the FeS0 4 series yielded no grain worthy the name in the first crop. Again in agreement with the results of the other series, consider- able discrepancy was found in duplicate pots so far as yields are concerned. In the case of the root yields, we have also large discrepancies between duplicate pots. However this may be, the straw yields in the treated pots of the first crop surpass those of the untreated pots in almost all cases, even if the higher figure for straw yields of the control pots be employed as a cri- terion. This is not so for the yields of roots ; and while aver- age yields show definite stimulation by FeS0 4 for root produc- tion of barley plants on the greenhouse soil, single values from duplicate pots do not justify any conclusions of that nature. Despite all this, there is certainly no reliable evidence of definite toxic effects on the part of FeS0 4 to barley plants under the conditions of this experiment. In general, therefore, the results of the FeS0 4 series are not unlike those of the CuS0 4 series, and the ZnS0 4 series on the greenhouse soil so far, at least, as the first crop is concerned. Second Crop It will be remembered again that the amounts of FeS0 4 employed for the first crop were doubled before planting the second crop. On studying the yields of the latter, one is at once struck by the strong parallelism in effect exerted on the barley plants by ZnS0 4 and FeS0 4 in the second crop. Both stimulate total dry-matter production in the very low concen- trations and yet the discrepancies between the actual amounts of salts used in the two cases are of course very large. Besides, both seem to stimulate root development and, very slightly, the production of straw, at certain concentrations. Again, there appears to be indirect evidence that most of the salt applied is not only rendered insoluble, as is probably the case with FeS0 4 , 1917] Lipman-Gericlce : Smelter Wastes and Barley Growth 519 but that much of the salt remaining is adsorbed by the soil and becomes inactive so far as the barley roots are concerned. Third Crop In table Vic, which sets forth the yields of dry matter obtained in the third crop of the FeS0 4 series, we find some data of unusual interest. Despite discrepancies in the weights of dry matter obtained in duplicate pots, there can be little question that the higher concentrations of FeS0 4 , beginning with 1.4 per cent, definitely stimulate straw production, while the lower concentrations employed, less definitely but probably without doubt, depress it. Grain production, on the other hand, seems to have been stimulated in the third crop by all concentra- tions of FeS0 4 employed, and the yields are high enough and agree well enough in the duplicates to justify that conclusion. In the case of the roots, still another effect was probably induced by FeS0 4 . No stimulation can be definitely noted, yet the toxic effect, if any, is small and apparent in very few instances. In the case of the total dry matter produced, marked stimulation seems to have been obtained at concentrations of FeS0 4 respec- tively of 1.4 per cent, 1.6 per cent, and 2 per cent. When com- pared with the third crop of the CuS0 4 and ZnS0 4 series, the third crop of the FeS0 4 series stands out sharply. It gives stimulation only at the higher concentrations, the ZnS0 4 gives no stimulation and almost positive toxicity throughout, and the CuS0 4 gives stimulation almost throughout the whole series in the third crop. While all three of the salts may be quite harm- less and even stimulating in relatively small quantities, they manifest very definite and specific characters when employed in higher concentrations and when results are obtained on the same soil for more than one season. Lead Sulfate — Greenhouse Soil Entirely unlike the three salts thus far discussed, PbS0 4 exercises what appears to us to be a definitely toxic effect throughout the first crop. This observation must be considered separately for every crop. It should be noted that unlike the .320 t'mn rsity of California Publications in Agricultural Sciences [Vol. 1 copper, zinc, and iron salts. PbSO, was applied unci' only prior to planting the first crop. First Crop Like ZnS0 4 and PeS0 4) the PbSO, was tested in the green- house soil only. The yields obtained in the PbS0 4 scries are given in table Vila, VII6, and VIIc. They will be discussed in conjunction with the comment already made with reference to the aspect of the plants in the 1*1>S< I, series. It will he noted there that the plants possessed little rigidity, were deep green in color, and in general assumed a sprawling or prostrate, in- stead of an erect, habit of growth. This was a result of some specific reaction of PbSO, and was exerted even though only small quantities of the sail could have existed in the soil solu- tion, owing to tic insolubility of the salt. It should also 1"' observed in this scries, as it has been in the others, thai the quantity of Phsn, employed seemed to have Little relation to its toxic effects on the yields of straw. The lack of "fain produc- tion has already 1 n explained in other discussions above ami is connected not with an\ sail treatment, bul with the condition of the greenhouse soil itself, of which more detailed discussion has been given. Root production was particularly affected in a deleterious manner by PbSO, in the firsl crop. Roughly speaking, it was reduced in tic PbSO, treated pots by more than 60 per cent of the yield obtained on the untreated or control pots. In other words, in this series, as in many others, rool production and straw production run almost parallel. This is further evidenced by the uniformly depressing effeel of PbSO, regardless of the quantity in which it was employed. We find therefore iii PbSO, (and in Pb, I ause all the sulfates used have a common anion 1 a substance which in the firsl crop on the greenhouse soil exhibits characteristics totally different from those of copper, /inc. and iron under similar circumstances. Tims while the three salts last named show definite powers of stimulating barley growth in the first crop on the greenhouse soil, lead \ity markedly depresses the growth of that plant under the same i ditions. 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 521 Second Crop In the second crop quite different conditions obtain with respect to the effects of PbS0 4 . While nearly all of the higher concentrations of the series are still toxic to barley, three of the lower concentrations, including 600 p. p. m., are distinctly stim- ulating to that plant. If it were not for injury to the plants by mice, the concentrations of 200 p. p. m. and 400 p. p. m. PbS0 4 would doubtless have shown as much stimulation as the others just mentioned. In other words, taking the total dry matter produced, it seems true beyond cavil that in the second crop on the greenhouse soil, PbS0 4 in very considerable con- centrations acts as a stimulant to barley growth. With reference to the separate fractions of the total dry matter produced in the second crop of the PbS0 4 series, we note some interesting facts. In the first place, no grain was pro- duced in the second crop of the lead series. This is very difficult to explain, since the control pots and the treated ones behaved similarly in that regard. In view of our statements in the intro- ductory portion of this paper, we can scarcely believe that the mere location of the plants of this series in a somewhat shaded part of the greenhouse can account for the discrepancy. The root yields were nearly all depressed by the action of PbS0 4 in the second crop. The exceptions to this rule were in isolated pots with no duplicates to confirm them. It would therefore seem that PbS0 4 is toxic to the root development of the barley plant even in the second crop, in spite of its stimulating effect on the straw yield at certain concentrations. Such effect of PbS0 4 is unlike that of any of the other salts, which, at least at a number of concentrations, stimulate root development, par- ticularly so in the case of CuS0 4 and ZnS0 4 . Third Crop A progressive improvement may be seen in the soil treated with PbS0 4 as crop follows crop. Just as the second crop gave very much better results than the first, so the third crop gave very much better results than the second. In the third crop the stimulation to the growth of barley exerted by PbS0 4 is, however, the most striking, since it obtains particularly at 522 University of California Publications in Agricultural Sciences [Vol. 1 the higher concentrations of PbS0 4 . As was the case with some of the other salts in other crops, PbS0 4 seems to be toxic in the third crop at the low concentrations at which it stimulated growth in the second crop. On the other hand, it stimulates growth as above stated in the third crop at some of the higher concentrations at which it was toxic in the second crop. However, most of the stimulating influence of PbS0 4 , and perhaps all of it, in the third crop affected the straw production and not the root yields. This is again at variance with the results obtained in many of the other series above described, in which the usual condition was a parallelism between the effects exerted by a salt on the different fractions of the total dry-mat- ter yields. Thus very good straw yields were obtained in most of the pots of the series in the third crop and instances of in- creases over those of the control pots were numerous, but no definite evidence of such stimulation in the case of the roots could be noted. In the case of the grain, on the other hand, the higher concentrations of PbS0 4 seemed to be as definitely stim- ulating as they did in the case of the straw yields. This is in almost entire harmony with PeS0 4 in the third crop, but has little resemblance to the corresponding CuS0 4 and ZnS0 4 series. Potash Alum — Greenhouse Soil This salt was tested in these experiments because it had been proposed that if it was not detrimental to soils and crops, it could be employed as a source of potash for fertilizers. It could be cheaply obtained in all probability by treating granitic rock containing adequate percentages of potash, with H 2 S0 4 , which can be manufactured in large quantity by the important smelter plants through the oxidation of S0 2 fumes. In view of the foregoing, potash alum was applied, as indicated in tables Villa, VIII6, and VIIIc, which are given below, on the basis of a certain number of pounds per acre, beginning with 300 pounds K 2 per acre in the form of KA1(S0 4 ) 2 .12H 2 and going up to 2000 pounds K 2 per acre in the same form. 1917] Lipman-Gericlce : Smelter Wastes and Barley Growth 523 First Crop Table Villa shows clearly that the application of potash alum in the first crop was distinctly stimulating to the barley plant so far as the production of total dry matter is concerned. The degree of stimulation is not unlike that of CuS0 4 , ZnS0 4 , and FeS0 4 in the first crop and, again, seems to be about the same with the lower as with the higher concentrations. When we consider the root yields separately from the straw yields we find, however, that the former were not increased by the potash alum treatment, though they were scarcely depressed with any concentration of the salt. Second Crop With the concentration of potash alum doubled in the second crop, the marked evidences of its stimulating effect on barley growth are still manifestly present. The entire series of treated pots, when averages of total dry matter produced are taken as the criterion, gives results far superior to those of the control pots, even though there is variation among the latter and among the treated pots in duplicate cultures. So far as the production of the total dry matter of barley is concerned, there appears to be no evidence in the second crop and very little, if any, in the first, of any toxic properties of potash alum. We may now consider briefly the separate parts of the total dry matter as affected by the potash alum. The yield of straw is without exception greater in the treated than in the untreated pots of the second crop of the potash alum series. That part of the total dry matter has therefore been very materially in- creased by the potash alum application. The grain yields in the absolute were of very great magnitude and amounted in many cases to as much by weight as the dry matter of the straw. In some cases they even excelled the latter. This is analogous to the condition of the second barley crop in the CuS0 4 series, which was the only one of the other series manifesting as high a grain production. Not only, however, were the grain yields large in the absolute, but they indicated clearly the stim- ulating effect of potash alum on their production, since all the treated pots yielded much more grain than the control pots. 524 University of California Publications in Agricultural Sciences [Vol. 1 In the second crop, on the other hand, as in the first, the Larger amounts of potash alum were neither inferior nor superior to the smaller amounts in increased production of straw and grain, but were of about the same influence throughout. Consistent with the effect of potash alum on the straw and grain yields was that on the root yields. The latter were, throughout the whole series in the second crop, increased by the potash alum applica- tions and, as in the cases of straw and grain, independently of the amounts of potash alum employed. We have, therefore, another phase of analogy between the potash alum and the CuSO., series in the second crop winch seems only to make the resemblance stand out in greater relief. The production of every part of the plant in the Second crop was stimulated by both potash alum and by CuS0 4 , but not by the other sulfates employed. Third Crop Wholly at variance with the effects just noted are those observed in the third crop of the potash alum series. So far from stimulating the growth of barley in all respects, as it did in the first and second crops, and particularly in the latter, potash alum in any and all concentrations depresses the growth of barley when the yields of total <\v\ matter are used as a basis of comparison. This is true also for the straw and root yields taken separately, with the possible exception of the straw yield with the lowest concentration of potash alum. In the case of the grain yields, however, no indubitable evidence of a depress- ing effect by the potash alum is at hand. It is indeed not im- possible that definite though small effects of potash alum stimu- lating to grain production in the third crop might be allowed in some of the concentrations of the salt employed. The explana- tion of this striking' change in the effects of potash alum in two successive crops is obviously not simple, though several possible explanations immediately suggest themselves. It is probable that the most favorable explanation would be over-stimulation of plant growth in the first two crops and the removal of most of the easily available bases in the soil, leaving an impoverished soil condition and perhaps a so-called "physiological acidity," 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 525 which would of course react deleteriously on the development of the barley plant. Again, the washing out of the salt by irri- gation may have caused physical conditions in the soil which are inimical to the proper air and water supply for both plants and the soil bacteria. The first conception is the one employed to a considerable extent by the "old-line soil chemist" to explain the depressing effects on soil fertility of the large and continued use of gypsum. The second is a condition demonstrated in this laboratory recently 7 to be of considerable importance. Further discussion will be accorded this subject in a general comparison given below of our results with those of others. In general it may be added that the results of the third crop in the potash alum series are more in keeping with those of the ZnS0 4 series than with those of any other series discussed. Manganese Sulfate After our work on the effects of the compounds mentioned on barley plants had been under way for one season, it was deemed advisable to inaugurate some new experiments, using manganese salts. The latter it will be remembered were rep- resented by MnS0 4 in preliminary experiments by F. H. Wilson and the senior author, which are cited above. Owing to the fact that the preliminary experiments with manganese had shown the latter to be comparatively innocuous, and even stim- ulating at considerable concentrations, for barley and vetch, larger amounts of manganese than of copper and zinc were em- ployed. Both MnS0 4 and MnCl, were tested. Each of these salts will be considered separately, and tables IXo, IX&, and IXc, which follow, give the plan and the results of the experi- ments with MnS0 4 . In the case of both manganese salts, only one application was made, and that was prior to the first crop. First Crop It becomes at once clear from an examination of table IX« that we can find in the first crop no indubitable evidence of Univ. Calif. Publ. Agri. Sei., vol. 1, no. 10, p. 291. 526 University of California Publications in Agricultural Sciences [Vol. 1 toxicity for barley of MnS0 4 even when amounts of that salt equivalent to 0.6 per cent of the dry weight of the soil were used. On the other hand, the stimulating effect of MnS0 4 for barley in the first crop on the greenhouse soil appears to be clearly evident. This is particularly true for the first three con- centrations, amounting respectively to 500, 1000, and 1500 p. p. m. At concentrations exceeding 1500 p. p. m. MnSO.,, the stim- ulation is only slight, and three concentrations — namely, 3500 p. p. in., 4000 p. p. in., and 5500 p. p. m. MnS0 4 — possibly de- press barley growth to some extent. The latter effect can scarcely be taken as indicating definite toxicity, however, since, as above pointed out, even the highest concentration employed (6000 p. p. m. MnS0 4 ) appeared to stimulate barley growth slightly, and the toxic evidences referred to are noted at concentrations which lie between slightly stimulating concent rat ions on both sides. At any rate, we have no evidence of the toxicity of MnS0 4 in the first crop until concent cat ions equivalent to 3500 p. p. m. of MnS0 4 are reached. When the root and straw yields are considered separately in the first crop, some interesting observations may be made which are not possible when the dry matter is considered as a whole. For example, stimulation to root development in the first crop of the MnS0 4 series is apparent only in the first three concentra- tions above noted as giving the largest yields of dry matter. Moreover, the straw yields are also distinctly higher at those same concentrations. But whereas MnS0 4 gives evidence of toxicity to root development, either slightly or definitely, at all concentrations tried above 1500 p. p. in., it continues beyond that concentration to be slightly stimulating to straw production. In comparison with the other salts above described, MnS0 4 is distinctly superior in the magnitude of its stimulating effects. The only other salt which manifests some resemblance to MnS0 4 in that respect is CuS0 4 . Since the concentrations of these two salts here employed, however, are very different from each other in the two cases, no more detailed comparison would be wholly justified. 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 527 Second Crop When the total dry matter of the second crop in the MnS0 4 series is considered (table IX&), we find that not only has the stimulation noted in the first crop disappeared, but that an act- ually definite toxicity has supplanted it. Moreover, such toxicity is as marked with the lowest as it is with the highest concentra- tions of MnS0 4 , and it is even possible that the former definitely surpass the latter in that respect. Again, as in some preceding cases with other salts, the total dry-matter yields do not give a complete picture of the effects of MnS0 4 on barley growth. Thus if we consider the straw, grain, and root yields separately, we find data leading to conclusions slightly different from those above. For example, whereas both the grain and root produc- tion are definitely depressed at all concentrations of MnS0 4 in the second crop, this is not so for the straw yields. The latter are in many instances, including the cultures of the highest concentrations of MnS0 4 , increased by the effects of the salt. Were it not for the lack of agreement in some of the duplicates, we might add more emphatically that straw yields are markedly stimulated by MnS0 4 in the second as in the first crop on the greenhouse soil. This seems particularly true at the higher concentrations of the latter salt, but is also apparent at some lower concentrations. Since, therefore, no grain was produced in the first crop, and since only three of the lowest concentra- tions of MnS0 4 in it gave stimulation to root development, it seems not unreasonable to consider that the results of the second crop in the MnS0 4 series are, in the large, not essentially differ- ent from those of the first crop. The outstanding result is the stimulation to straw production which is noted, and that is differ- ent in degree only, not in kind, in the two crops here considered. Despite all this, however, we do not attempt to disregard the differences which characterize the effects of MnS0 4 in the first and second crops as above pointed out, but we regard them as of minor significance. When we compare MnS0 4 in the second crop with other salts under similar circumstances in the greenhouse soil, we find that it has but little in common with them. It approaches perhaps most closely the behavior of PbS0 4 in the second crop, but is 528 University of California Publications in Agricultural Sciences [Vol. 1 different from it in several important particulars. As a general thing-, the other salts still give more stimulating effects in the second crop so far as the total dry-matter production is con- cerned, but this is not true in any instance of the second crop of the MnS0 4 series. It should be borne in mind, however, that the manganese series is not comparable with the others except possibly with the lead series, because only one treatment, prior to the first crop, was given. Third Crop The depressing effect exerted by MnS0 4 in the second crop of barley, at least so far as the grain and straw yields are con- cerned, appears to have been merely an ephemeral one. There was not only a total disappearance thereof in the third cro*p, but an actually stimulating effect seems to have replaced it ; and to have extended to straw, grain, and root production and was not confined, as in the second crop, merely to straw production in part of the series. Moreover, the stimulating effect of the MnS0 4 appears to have extended throughout all concentrations and would seem to have been greatest at the medium high con- centrations, as is indicated in table IXc. While much better agreement between duplicate determinations could have been desired, the clear superiority in yield of the majority of treated pots, when compared with the controls, leaves scarcely any room for doubt that we are here confronted with real cases of stimu- lating effects. The results are the more interesting and striking since large concentrations of MnS0 4 are involved. The results call for further observations on the apparent reversal of results between the second and third crops and between the second and first crops. Unfortunately, no definite leads are in our pos- session which would aid us in answering this question. Theo- retically, however, it would seem possible to explain the facts as follows : In the first crop the large quantity of organic matter present in the soil brings about the adsorption of the MnS0 4 and leaves the active soil solution relatively dilute in that salt. This low concentration acts as a stimulant to both the higher plants and the soil flora and induces an increased yield. After one season of exposure to sun and cultivation, the soil loses a 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 529 considerable portion of its organic-matter snpply and therefore possesses a much smaller surface for adsorption of MnS0 4 Hence the usable portion of the soil solution would tend to become more concentrated with respect to that salt and induce depressions in yield of roots and grain. By the time the third crop is planted, thorough oxidation of the MnS0 4 has occurred and most of the manganese is rendered insoluble, thus leaving again only a small quantity of the salt in the soil solution. This acts as a stimulant, as it did in the first crop, and induces an increased yield again. This explanation, while open to question in one or two important respects, may prove of some assistance in the ultimate clearing up of the somewhat perplexing facts which are here considered. Other explanations, involving the relationship of MnS0 4 to the soil colloids and to other phases of the soil solution besides that above mentioned, offer them- selves at this time, but they must all await the further study of fundamental principles of plant physiology before they can be considered to advantage. Irrespective of the theoretical argu- ments which may account for the results obtained in the MnS0 4 series, the striking facts relating to the changes in effect on three successive crops of a given salt application made prior to the first planting are of great practical moment. Not only do they render of doubtful value for practical purposes one season's results on the effects of salts on crops, but they cause one to wonder if anything less than five successive crops should ever constitute sufficient evidence upon which to base a judg- ment. Taking all of our results together, it may be said in general that MnS0 4 is to be regarded, for a limited period at least, as definitely stimulating to barley growth in soils. Manganese Chloride As pointed out above, MnCl, was tested along with MnS0 4 , so that manganese in different compounds might be studied for itself as well as in comparison with other elements. The experi- ment was arranged similarly to that of the MnS0 4 series, and details with respect to it, together with the results obtained, are set forth in tables Xa, X&, and Xc for the three crops grown. 530 University of California Publications in Agricultural Sciences [Vol. 1 First Crop Table Xa shows the striking effects of concentrations of MnCl 2 on barley growth in the greenhouse soil during the first crop. Whereas the first three concentrations of that salt, namely 500 p. p. hi., 1000 p. p. in., and 1500 p. p. m., give veiy marked stimulation to barley growth (far more indeed than that given by similar concentrations of MnS0 4 ), amounts in excess of 1500 p. p. m. MnCl 2 are very markedly toxic. This toxicity increases strikingly with the increase in concentration in MnCl 2 beyond 2500 p. p. m., until at a concentration of 6000 p. p. m. almost no growth is obtained. Even the difference between 1500 p. p. m. and 2000 p. p. m. in the soil means a change from a high degree of stimulation for barley production to a marked toxicity and a decrease of about 50 per cent in the yield. No series of salt concentrations studied by us and reviewed above gave anything like the sharpness of manifestation of toxicity that is noted in the first crop of the MnCl 2 series. We are evidently dealing again with the acute toxicity of chlorine for living cells which we have on other occasions pointed out in various connections. This is true, if we may repeat again, despite the fact that at the lower concentrations, chlorine may, as is strikingly exemplified in table Xa, give astounding evidences of stimulation to barley which surpasses any noted above with other and more uniformly stimulating substances. When we study straw and root yields separately we find that, in general, the effects of MnCl 2 are similar with respect to both in the first crop. The roots are, to be sure, only slightly stimulated in growth in the first three concentrations employed, whereas the tops are enormously stimulated. When, however, the toxicity of MnCl 2 becomes apparent, it is equally striking in the roots and tops, as the figures in the table clearly show. While in some respects, therefore, and particularly as regards stimulation, the MnCl 2 behaves like the MnS0 4 in the first crop and the first three concentrations, it is totally different from the latter salt in giving marked evidences of toxicity at concentra- tions in excess of 1500 p. p. m. Nevertheless MnS0 4 still con- tinues to stimulate growth, even though it does so very slightly throughout the series. On the other hand, although the resem- 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 531 blance between the behavior of MnS0 4 and MnCl, in the first crop is limited in extent, MnCl 2 resembles MnS0 4 much more in its effects on barley growth in the first crop than it does any of the other salts under similar circumstances. Again, we are obliged to stop with this general comparison owing to the high concentrations of MnCl 2 employed, as compared with the rela- tively much lower or much higher concentrations of the other salts employed. Second Crop When the total dry matter is considered (see table X6), the second crop of the MnCl, series gives the latter salt a reversal of form. At the first three concentrations at which it notably stimulated the production of dry matter in the first crop, it becomes decidedly toxic in the second crop. On the other hand, at the concentrations above 1500 p. p. m., at which it was acutely toxic in the first crop, MnCl 2 is stimulating when the total yields of the treated as against those of the untreated pots are considered. Such marked reversal of effects of MnCl 2 between two succeeding crops on the same soil needs further attention under the general discussion below. Following the procedure employed in the case of the other series, we may now study sep- arately the yields of straw, grain, and roots as given in table X?;. Taking the straw yields first, we find that they were, in all cases but one or possibly two in the series, much larger than those of the control pots, and that at concentrations in excess of 1500 p. p. m. the average yield of straw was nearly twice as great as that of the control pots. While different in degree, therefore, this effect of MnCl 2 in the second crop is very similar in kind to that exerted by MnS0 4 in the second crop with respect to the yield of straw. In the case of the grain, however, we find totally different conditions, for here only one case of stimulation is noted and that, owing to the great discrepancy in the duplicates, is an unsafe one to accept. In excess of 3000 p. p. m., MnCl 2 mani- fests a very marked toxicity so far as grain production is concerned, until at 6000 p. p. m. very little or no grain is pro- duced. This result is again different only in degree, not in 532 University of California Publications in Agricultural Sciences [Vol. 1 kind, from that of the corresponding one in the MnS0 4 series. Respecting root yields, the toxic effects of MnCL in the second crop are apparent throughout the whole series. While the de- creases are not quite so great at the lower concentrations of MnCL as they are at the higher concentrations, they are not far different, and in general amount to from 40 to 60 per cent of the amount yielded by the control pots. We see in the root yields, therefore, a further analogy between the second crop of the MnCL series and that of the MnS0 4 series. In brief, it should be observed that while wide discrepancies in total yields of dry matter are noted between the second crops of the MnCL and MnS0 4 series, the discrepancies are superseded by striking resemblances when the straw, grain, and root yields are com- pared separately in the two series. Since the differences seem to be those of degree only, is it not possible that we have here the dominant manifestations of the effects of manganese, which are only slightly modified by the element or elements combined therewith? If this were not the case, would we not expect to find much larger discrepancies between the two series in ques- tion, based on the specifically different effects of the -CI and the -S0 4 ions on barley growth? Third Crop The stimulating powers of manganese, as exemplified in the effects of MnS0 4 ions on the third crop of barley, are again manifest but very much more strikingly in the third crop of the MnCL series. While the yields of duplicate pots still fail to agree closely in a number of the salt concentrations tested, they show a much better agreement than those of the MnS0 4 series. At any rate, there can be no doubt of the stimulating effects of manganese chloride for barley grown in the greenhouse soil even in the third crop. Again, as was the case in the MnS0 4 series, the MnCL stimulates the production of all parts of the plant and not merely of any one portion of the dry mat- ter thereof. Thus, for example, whereas there was practically no stimulation to grain production in the second crop of the MnCL series, the third crop shows such stimulation markedly throughout the series. In no case, further, so far as the total 1917] Lipman-Gcrickc : Smelter Wastes and Barley Growth 533 dry weight produced is concerned, did any of the treated pots produce so low a yield as the control pots, when averages are considered. The great immunity to chlorine which the plants in the third crop of this series manifest is very difficult to explain. In general, however, the changes in the effects of MnCl 2 from one crop to another are much the same in nature as those of the MnS0 4 series which have been discussed more in detail above. It looks obvious that we are dealing primarily in both manganese series with the effects of the kation rather than with those of the anions, though, to be sure, specific effects of the latter do not seem to be wanting. The balance of the data presented in table Xc speaks for itself. COMPARISON OF OUR RESULTS WITH THOSE OF PREVIOUS INVESTIGATORS It is quite unnecessary to review in detail the results of the numerous investigations which bear on the subject in hand, par- ticularly those relating to copper and its influence on living organisms. Although, therefore, we are herewith citing a very extensive bibliography, we shall make no attempt at reviewing all of the investigations which have been carried out. It does seem desirable, however, to compare in general the results of our investigations with those of other researches in the hope that we may thereby arrive at some definite understanding, now that so much experimental work has been accomplished, as to the real status of the salts in question in the realm of plant physi- ology. In order to simplify such discussion, we shall take up the different so-called toxic metals separately. Copper Sulfate As pointed out above, the bibliography on the subject of copper and its effects on plants is very extensive. One needs but to turn to the complete reviews of it by Czapek, s Pfeffer, 8 Biochemie der Pflanzen, vol. 2, p. 910, Jena, 1905. '■> Pflanzenphysiologie, vols. 1 and 2, Leipzig, 1897 and 1901. 534 University of California Publications in Agricultural Sciences [Vol. 1 and Brenchley 10 to be confirmed in that opinion. The general impression given by the reviewers is that so far as plants are concerned, copper is to be regarded as a distinctly toxic sub- stance. To quote Brenchley from the work above cited, for example : ' ' Altogether, after looking at the question from many points of view, one is forced to the conclusion that under most typical circumstances, copper compounds act as poisons to the higher plants, and that it is only under particular and peculiar conditions and in very great dilutions that any stimulative action on their part can be clearly demonstrated." This state- ment is not qualified with respect to the kind of medium em- ployed for testing the effects of copper on plants. But whether it be applied to solution or to soil cultures, it would scarcely seem to be adequately supported by experimental evidence, and particularly is this true regarding soil cultures. In solution cultures, copper in various compounds was found to be toxic to the higher plants by Otto, 11 Haselhoff, 12 Coupin, 13 Kanda, 1 * True and Gies, 15 True and Oglevee, 18 Jensen, 17 Brenchley, 18 Heald, 1!l Harter, 20 and Haywood.-' 1 While exceedingly high dilutions of copper salts were employed by some of these in- vestigators, the possibility still exists in their work that the tin rest i races of copper may have acted as stimulants. More- over, in the case of Jensen's work the evidence on the toxicity of very dilute solutions of copper salts is really negative, since lie emphasizes principally the fact that no stinmlation was observed with CuS0 4 in solution cultures. io Inorganic plant poisons and stimulants, Cambridge, 1914. ii Ztsehr. Pflanzenkrank., vol. 3, no. 6; Bot. Cent., 56, p. 340; E. S. R,, 5, p. 649. 1^ Landw. Jahrb., 21, p. 263; E. S. E., 3, p. 499. "Comptes Rendus Acad. Sci., Paris, 127, p. 400; E. S. R., 10, p. 611. » Jour. Col. Sei. Imp. Univ. Tokyo, 19, p. 47; Bot. Cent. 95, p. 538; E. S. R., 16, p. 228. is Bull. Torr. Bot. Club, 30, p. 390. is Bot. Gaz., 39, p. 1; Science, 19, p. 421. i" Bot. Gaz., 43, p. 11. is Inorganic plant, poisons and stimulants, Cambridge, 1914. io Bot. Gaz., 22, p. 125. =0 TJ. S. Dept. Agr., Bur. PI. Ind., Bull. 79, p. 40. 2i U. S. Dept. Agr., Bur. Chem., Bulls, nos. 89, 113, and 113, revised. 1917] Lipman-Gericle : Smelter Wastes and Barley Growth 535 Opposed to the findings of the investigators just named were those which showed evidence of stimulating effects of cop- per salts to plants in solution cultures. Among these investi- gators were Tschirch, 22 Montemartini, 23 and Forbes. 24 So far as germination of seeds is concerned, Effront 25 also noted the stimulating effect of copper. Owing to conflicts in the results obtained by different investigators working with copper in solu- tion cultures, one seems scarcely justified in subscribing to the statement above quoted from Brenchley, even if it were made to apply only to solution cultures. As Dr. Brenchley herself admits, there is no absolutely satisfactory method for determin- ing whether or not a certain substance is toxic or stimulating to plants. But from the theoretical standpoint of ascertain- ing how the protoplasm of the plant is affected by a given substance, if at all, the solution-culture method is the only one involved, since the other methods are confessedly not intended to show anything more than effects of substances on plants under conditions closely approximating the natural. If, then, the solution culture method is the only one among those at present known that is suitable for studying the effects of different chem- icals on plant growth in a more or less intimate way, why do we obtain the conflicting results above noted with respect to the effects of copper on plants ? The answer to this question is to be found in a number of circumstances surrounding the manipula- tion of the solution-culture method. Some investigators use distilled water, others use tap water, still others physiologically balanced solutions of a large variety. For reasons well known to plant physiologists, the results of such different media among the solution cultures must show wide discrepancies. If, however, the claim is made that all media but pure distilled water be discarded in such work, owing to the factors of salt antagonisms which enter into salt solutions to vitiate results, a very strong counter-claim can be made. The protoplasm of plant cells is not in a natural medium when it is placed in distilled water, and 22 Abstract in Chem. Ztg., 18, p. 320; E. S. R., 6, p. 872. 23 Staz. Sper. Agr. Ital., 44, p. 564. 2* Results soon to be published, Univ. Calif. Publ. Agri. Sci. 25Compt. Rend. Acad. Sci. (Paris), 141, p. 626; E. S. R., 18, p. 126. 536 University of California Publications in Agricultural Sciences [Vol. 1 hence it may manifest distress and weakness which under nat- ural conditions might be quite impossible. Owing to osmotic influences, the plant would lose salts and other substances to the distilled water more quickly and in larger quantity than to tap water or to a balanced solution. It would therefore be more subject to weakening or to the absorption of toxic materials in the former than in the latter medium. In other words, under such circumstances copper, for example, would merely exagger- ate the untoward conditions for plant growth, while it might have no power to affect the plant under more favorable condi- tions. Again, seeds are not usually allowed to germinate in the solution which is to be tested in the cultures, but in a medium of a harmless nature. Does not sudden removal to salt-solution cultures render them less immune to certain substances than if they had been allowed to accustom themselves from the begin- ning to a given salt ? We do not desire to give the impression from these arguments that we deprecate the use of the solution-culture method. On the contrary, we think it of great value in the study of many fundamental problems and also for obtaining relative data. When, however, one attempts to use it in drawing absolute conclusions for purposes of application to such a subject as that under consideration, it falls as far short of throwing light on the actual effects of a given substance on plant protoplasm (as the latter is situated under natural conditions), as does any other method of study now employed. We believe that the conflicts in the results just reviewed are perhaps explicable on one of the bases above discussed; and since no modification of the solution- culture method is free from serious objection, we must accord equal value to all results of reliable investigators. Consequently we arrive at the conclusion that in the experiments above cited there is no absolute evidence that copper is or is not stimulating to plant protoplasm in solution cultures. While there appears to be more evidence that copper is toxic under the conditions and in the concentrations named than that it is stimulating, we cannot admit that the plant has been tested in any two of the experiments under essentially the conditions of its natural 1917] Lipvian-Gericke : Smelter Wastes and Barley Growth 537 habitat. Since plants are, after all, to be found growing natu- rally only in soils, it cannot be a matter of indifference to ns, in attempting the study of the effect of a certain substance or substances on them, whether they are supplied with normal conditions for their development or not. Proceeding now to an examination of the results obtained by other investigators on the effects of copper on plants grown in soil or sand instead of solutions we find many interesting observations. Injurious effects of CuS0 4 at the rate of about 400, 800, and 1600 pounds per acre to potatoes and beans were noted by Steglich, 20 but he failed to observe such toxic effects on the same soil to strawberries or fruit trees. Haselhoff 27 claims also to have noted injury to grass, beans, and other plants from smelter smoke containing copper. Owing to other conflicting factors concerned in smelter-smoke injury, Haselhoff 's results are open to serious criticism. Simon 28 experimented with oats and mustard on garden soil, clay, and sand, and used amounts of CuS0 4 varying from 0.01 per cent to 10 per cent. His state- ments imply that copper was toxic throughout, with the oat plants showing more resistance than the mustard, and that CuS0 4 was least toxic in garden soil and most toxic in the sand. Opposed to the three cases just cited are numerous results show- ing the stimulating effects of copper to plant growth in soils. We find among these the results obtained by Girard, 29 Kanda, 30 Jensen, 31 Voelcker, 32 Forbes, 33 and Sachser. 34 A large number of observations have also been made on the stimulating effects, or lack of any effect, of copper sprays, and in other ways of the effect following direct contact of the copper solution with plant cells, among which may be mentioned those of Prank and 26 Ber. Tat. Landw. Abt. K. Vers. Stat. Pflanzenkult, Dresden, p. 4, 1903; E. S. E., 16, p. 133. 27 Fiihling's Landw. Ztg., vol. 57, no. 18, p. 609; E. S. E., 20, p. 831. 28 Landw. Vers. Stat., 71, p. 417 ; E. S. E., 22, p. 439. 29 C. E. Acad. Sei., Paris, 120, p. 1147; E. S. E., 7, p. 99. so Jour. Col. Sci. Tokyo Imp. Univ., 19, p. 47 ; E. S. E., 16, p. 228. 3i Bot. Gaz., 43, p. 11 ; E. S. E., 18, p. 625. 32 Jour. Eoy. Agr. Society, England, vols. 73, 74, and 75, Eeport for 1912, 1913, and 1914. 33 Univ. Calif. Publ. Agr. Sci., 1, no. 12, 1917. 34 Cent. Agr. Chem., 33, p. 533 ; E. S. E., 16, p. 865. 538 University of California Publications in Agricultural Sciences [Vol. 1 Kruger, 35 MacDougal, 36 Chuard and Porchet," 7 Demoussy, 38 Praudi, 39 Olive, 40 and Molinari and Ligot. 41 In addition to all these results, which show either no toxicity or decidedly stimu- lating effects on plants from the use of copper (usually CuS0 4 ) in soil, there are extant a number which testify to the high resistance of plants in soil to extremely large amounts of copper (Such, for example, as from 2 per cent to 5 per cent of the dry weight of the soil). Among these may be mentioned the observations of Van Slyke 42 and Pammel. 43 All of these findings render it extremely improbable that copper in soil, can at any time be considered definitely toxic in relatively small quantities (say, below 0.10 per cent of the dry weight of the soil). On the contrary, the evidence seems very well established that positive stimulation of plants may be induced through the use of small quantities of copper (say, from 0.01 to 0.05 per cent of the dry weight of the soil), in the form of CuS0 4 particularly, and possibly also in other forms. Our investigations as discussed would seem to confirm and be con- firmed by earlier investigations of the senior author and P. H. Wilson and by numerous other experiments carried out in differ- ent parts of the American and European continents and in Eng- land. These observations would appear therefore to refute the conclusion of Dr. Brenchley which is above quoted and to point clearly, through the added data which we have submitted, to the conclusion that copper in the form of CuS0 4 is to be re- garded, at some concentrations, as being decidedly stimulating to some plants grown in soils, and, what is perhaps more im- portant, relatively innocuous in large amounts. The mechanism of the stimulation obtained does not involve one single effect, but probably several. We know, for example, through experi- ss Ber. deutsch. bot. Gesell., 12, p. 8 ; E. S. E., 5, p. 926. ssBot. Gaz., 27, p. 68; E. S. E., 11, p. 24. 3T Bull. Soc. Vaud. Sci. Nat., 4th series, vol. 36, p. 71 ; Bull. Murith. Soe., Valais Sci. Nat., no. 33, p. 204. 38 Ann. Agron., 27, p. 257; E. S. E., 13, p. 657. soStaz. Sper. Agr. Ital., 40, p. 531; E. S. E., 19, p. 755. 40 S. Dak. Agr. Exp. Sta., Bull. 112 ; E. S. E., 21, p. 436. 4i Ann. Gembloux, 18, p. 609 ; E. S. E., 20, p. 873. " N. Y. Agr. Exp. Sta., Bull. 41. "3 Iowa Agr. Exp. Sta., Bull. 16. 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 539 ments 44 carried out in our laboratory, that copper is markedly effective in increasing the nitrifying activity of soils ; we know, from other results which we have obtained, but not yet published, that the minerals of the soil are rendered more easily available through the action of CuS0 4 ; we know from the results of Porchet and Chuard that plant cells may be directly stimulated by CuS0 4 . It is therefore reasonable to explain any stimulating effects of copper in soil cultures as being of a complex nature and the results of better conditions for plant growth either directly or indirectly induced by copper through influences known to be characteristic of it as just explained. Zinc Sulfate We may now review, in a manner similar to that employed for CuS0 4 , the results obtained by other investigators as com- pared with our results on the effects of ZnS0 4 on plant growth. Data indicating the toxicity of zinc to plants grown in solution cultures have been obtained by Baumann, 43 Jensen, 46 Krauch, 47 Storp, 48 True and Gies, 4!) and Brenchley. 50 Most of these toxic effects were obtained with relatively small quantities of zinc salts and usually under conditions antagonistic to their toxic effects owing to the presence of nutrient salts. As opposed to these evidences of the toxicity to plants of zinc, we have at times, in the work of the same investigators, manifestations of the stimulating effects of zinc in solution cultures. For example, Brenchley admits in the monograph cited a slight stimulation of peas by ZnS0 4 , while showing the latter to be toxic to barley. Jensen, too, whose work is described, while obtaining no stimu- lation for ZnS0 4 , likewise showed no toxicity thereof in dilute solution, and expressed the opinion that the possibility exists of 44 Lipman and Burgess, The Effects of Copper, Zinc, Lead, and Iron on Ammonification and Nitrification in Soils, Univ. Calif. Publ. Agri. Sci., vol. 1, p. 127. 45 Landw. Versuchs. Stat., 31, p. 1. 4 6Bot. Gaz., 43, p. 11. « Jour, fur Landw., 30, p. 271. 4 « Landw. Jahrb., 12, p. 795. « Bull. Torrey Bot. Club, 30, p. 390. 50 Inorganic plant poisons and stimulants, Cambridge, 1914. 540 University of California Publications in Agricultural Sciences [Vol. 1 a stimulating power of ZnS0 4 at still greater dilutions than those which he employed. More direct evidence of the stimulating effects of ZnS0 4 is given by Kanda 51 in solutions free from nutrient salts, and by Javillier 52 in nutrient solutions. So far as solution cultures of all kinds are concerned, therefore, the evidence with respect to the effects of zinc on plants is conflict- ing, it being as strong on the side of stimulation at great dilutions of ZnS0 4 as on that of lack of it or of definite toxicity. Let us now examine the data available in which a solid substratum such as sand or soil is used instead of the solution. Direct observation of toxicity of zinc to plants in solid media is given by Storp, whose work is above cited, by Noble, Baessler, and Will, 53 Jensch, 54 Ehrenberg, 55 and Haselhoff and Gossel. 56 Evidence of the non-effectiveness of zinc either as a toxic or stimulating agent is given by Phillips, 57 by Holdefleiss, 58 and by Haselhoff and Gossel 59 As against these results, however, we have many others showing definitely stimulating effects of zinc on plants grown in sand or soil. Among them may be mentioned those of Kanda, 60 Jensen, 01 Silberberg, 62 Zaleski and Reinhard, 33 Ehrenberg, 04 Bertrand, 05 Nakamura (with some plants only), 60 Javillier, 07 Roxas, 68 Lipman and Wilson, 69 and the present writers. While, however, the evidence appears to si Jour. Col. Sci., Tokyo Imp. Univ., 19, p. 1. 52 Compt. Eend., etc., 155, p. 1551. 53 Landw. Versuchs. Stat., 30, p. 380. 54 Ztschr. Angew. Chem., 14, p. 5. ss Chem. Zeit., 32, p. 937. se Ztschr. Pflanzenkrank., 14, p. 193 ; E. S. E., 16, p. 952. 57 Chem. News, 46, p. 224. ss Landw. Versuchs. Stat., 28, p. 472. so Ztschr. Pflanzenkrank., 14, p. 193 ; E. S. E., 16, p. 952. eo Jour. Col. Sci., Imp. Univ. Tokyo, 19, p. 47. ei Bot. Gaz., 43, p. 11. 62 Bull. Torrey Bot. Club, 36, p. 480. 63 Biochem. Ztchr., 23, p. 193. 64 Landw. Versuchs. Stat., 72, p. 15. esEev. Sci. (Paris), 49, p. 673. 66 Bull. Col. Agr., Tokyo Imp. Univ., 6, p. 147. 67 Ann. Inst. Pasteur, 22, p. 720 ; also 7th Internat. Cong. Appl. Chem., see. vii, Agr. Chem., p. 163. 68 Philippine Agric. and Forester, 1, p. 89. 69 Bot. Gaz., 55, p. 409. 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 541 be overwhelmingly in favor of the stimulating effects of zinc to plant growth in soils, several instances of stimulation are quali- fied to hold for certain plants only or at very low concentrations of the metal. Therefore the data submitted are not as strong in favor of the stimulating effect of zinc salts to plants as one would suppose from the review above given. Nevertheless, it is strong enough in our opinion to satisfy even the critical that zinc can be a stimulant to plant growth in certain rather considerable con- centrations. Besides that, its toxic effects are nowhere to be regarded as very serious if small quantities of the salt are present. Our results indicate, in addition to all this, that ZnS0 4 , for example, may be stimulating to barley growth at consider- able concentrations, but that the after-effects on the soil in the third season or crop may be injurious. Such injury, however, is relatively speaking, not very great unless very high concentra- tions of ZnS0 4 are employed. Even in the third season of cropping in the case of the same soil, it appears that ZnS0 4 con- tinues to be stimulating to barley at a concentration of 200 p. p. m. of that salt as referred to the dry weight of the soil in question. Moreover, it is not unlikely that the reversal from a toxic to a stimulating condition occurring in the manganese series between the second and third crop might occur in the zinc series between the third and fourth crop. This possibility would seem to find some support from the fact that the third crop in the zinc series corresponds to the second crop of the man- ganese series, since two treatments — one before the first, and one before the second crop — were given to the zinc-treated pots. Iron Sulfate Results obtained in experimental trials with FeS0 4 in cul- tures of the higher plants have been perhaps more contradictory than those noted in the cases of CuS0 4 and ZnS0 4 which are reviewed above. This is particularly manifest in the extensive bibliography prepared by Horton 70 dealing with the use of sulfate of iron in agriculture. While the latter emphasizes primarily the results obtained with FeS0 4 in combating weeds, "o A Contribution to the bibliography of the use of sulfate of iron in agriculture, Chicago, 1906. 542 University of California Publications in Agricultural Sciences [Vol. 1 a large number of experiments are cited, among which are to be found eases of injury, ineffectiveness, and stimulation by FeS0 4 to crop plants. Very few experiments appear to have been reported on the effect on plant growth of FeS0 4 or other iron compounds in solution cultures. Those that are given indicate the uniformly toxic nature of iron to the higher plants under the conditions noted. For evidence on this point, the reader is referred to the investigations of Boiret and Paturel, 71 Gile, 72 Ruprecht, 73 Thompson, 74 and Knop. 75 No case has as yet come to our notice of the stimulating effects of iron salts to plants in solution cultures. In soil cultures the picture is an entirely different one, and it is under those conditions that we observe the contradictory results mentioned above. Distinct cases of injury by FeS0 4 to plants in soil cultures have been reported. In illustration of these, may be mentioned statements of Voeleker, 76 Steglich, 77 Nessler, 78 Ilalsted, 7 ' 1 and others. As showing FeS0 4 to be with- out effect on plants grown in soils, may be mentioned the experi- ments of Scovell and Peter, 80 A. Mayer, 81 Boiret and Paturel, 82 Petit, 83 Larbaletrier and Malpeaux, 84 and others. In other words, some of the investigators just mentioned, as well as Coste- Floret, 85 Brooks, SG Griffiths, 87 Treboux, 88 and a number of others, 7i Ann. Agron., 18, p. 417; E. S. E., 4, p. 435. 72 Jour. Agr. Res., 3, no. 3, p. 73 Mass. Agr. Exp. Sta., Bull. 161. -i Jahresber. Agr. Chem. N. F., 36, p. 106. '5 Landw. Versuchs. Stat., 2, p. 73. 7 « Jour. Roy. Agr. Soe. Eng., 2d ser., 1, p. 113. 77 Ztschr. Pflanzenkrank, 11, p. 31; see also Jahresber. Agr. Chem., 43, 352. 78 Centbl. Agr. Chem., 2, p. 125. 79 N. J. Sta., Ann. Rept., p. 321, 1890. so Ky. Agr. Exp. Sta., Bull. 17. si Jour, fiir Landw., 40, p. 19. 82 Ann. Agron., 18, p. 417. saCompt. Rend., etc., 117, p. 1105. s-i Ann. Agron., 22, p. 20. ss Prog. Agr. et Vit., 26, pp. 434, 463, 496. so Mass. Agr. Exp. Sta., Ann. Rept., p. 42, 1896. 87 Chem. News., 50, p. 167. ss Flora, 92, p. 59. 1917] Lipman- GerioTce : Smelter Wastes and Barley Growth 543 have noted very definite stimulation of plants by FeS0 4 in soil cultures. In addition to these direct results on the stimulation of plants, moreover, may be mentioned the numerous cases of stimulation of plants induced by spraying the leaves with solu- tions of FeS0 4 either for destroying ever-present weeds in crops or for overcoming certain diseases like chlorosis. These cases are too numerous to mention here, but are well reviewed in the bibliography prepared by Horton, which is referred to above. As the discussion of our results has shown, we are in accord with the idea of the stimulating powers of FeS0 4 even if used in rela- tively large concentrations in soils so far as the first two succes- sive crops on the treated soil are concerned. In the third crop also, marked stimulation is obtained, but only in the higher concentrations, which in the second crop were toxic. This circumstance will be critically considered below. Lead Sulfate The literature dealing with the subject of the effect of PbS0 4 or lead in any form on plant growth is very meager. That which is extant deals more specifically with the effect of lead sprays on foliage and fruit of trees than on the actual growth of trees, in which we are interested here. In the case of solution cultures we have found but two papers, and both of these testify to the stimulating action of Pb(N0 3 ), in dilute solutions. We refer to the investigations of Jensen 89 and Stoklasa. 90 In greater con- centration the Pb(N0 3 ) 2 was of course found to be toxic in the solution cultures. The same investigators also obtained marked manifestation of stimulation of plants in solid substrata due to lead. Jensen obtained such in quartz-sand cultures, in which greater concentrations were found stimulating than in solution cultures. Stoklasa confirmed the results of the solution cultures by field trials reported in the paper above cited, and also in other experiments 91 with sugar beets, oats, corn, and other crops. Voelcker 92 also found lead to be stimulating to wheat. When 89 Bot. Gaz., 43, p. 11. soCompt. Rend. Acad. Sci. (Paris), 156, p. 153. 9i Zuckerriibenbau, 18, p. 193 ; E. S. R., 26, p. 225. 9 2 Jour. Roy. Agr. Soc. Eng., 73, ent. series, 1912. 544 University of California Publications in Agricultural Sciences [Vol. 1 our data for PbS0 4 in greenhouse soil are reviewed in the light of the foregoing, they are found to be in accord with those of Voeleker so far as the second and third crops of barley are con- cerned. At some concentrations in both of those series, PbS0 4 acted as a stimulant to barley and often at very large or at the larger concentrations used. Our results, however, are entirely at variance with those of Jensen and Stoklasa in so far as the first crop is concerned. In that series we noted nothing but evidences of marked toxicity of the PbS0 4 , with the accompanying effects on the barley plants which are described. Potash Alum No literature has been found on the effects on plants of potash alum in soil. The discussion set forth above giving our results with that material will therefore have to suffice. Manganese With the possible exception of copper, manganese and its effects on plants have received more attention at the hands of plant physiologists and students of soils than any other element here under consideration. Despite that fact, there would appear to be as much contradiction in results obtained in this case as in those of the other elements above studied. We find reports of toxicity of manganese in solution cultures in the publications of Aso, 93 Loew and Sawa,' H and Brenchley.' 1 "' On the other hand, the results of the same authors also give evidence of the stimu- lating effects of manganese at certain concentrations. Miss Brenchley even hints at the possibility of the existence, simul- taneously, of a toxic and stimulating effect on the part of man- ganese and claims that either effect may show predominance, depending on the concentration of the salt employed. On the toxic action of manganese to plants in solid substrata, principally in soils, we have the reports of experiments of as Bull. Col. Agr., Tokyo Imp. Univ., 5, p. 177. '■>* Bull. Col. Agr., Tokyo Imp. Univ., 5, p. 161. 95 Inorganic plant poisons and stimulants, Cambridge, 1914. 1917] Lipman-Gericlce : Smelter Wastes and Barley Growth 545 Namba, 98 Voeleker, 97 Kelley, 08 and Guthrie and Cohen."" As opposed to these, however, we have numerous eases on record of the stimulating' effects of manganese to plants grown in soil, and even the work of the investigators last named is by no means to be considered as absolute evidence against such action of man- ganese, since the toxic action observed was in some cases very slight, and some of the concentrations involved were so un- usually high as to leave little expectation of anything but toxicity of manganese for the plants tested. Among the in- vestigators referred to who have furnished evidence of the stimulating effects of manganese, may be mentioned Voeleker, 100 Bertrand, 101 Roxas, 102 Loew and Sawa, 103 Nagaoka, 104 Loew and Honda, 10 "' Fukutoma, 100 Namba, 107 Uchiyama, 108 Takeuchi, 109 Feilitzen, 110 Strampelli, 111 and Lipman and Wilson. 112 While in this review we have omitted a number of the investigations bear- ing on the subject, enough have been given to indicate clearly the trend of the evidence in hand. Fuller bibliographies may be obtained in the excellent reviews of the literature given by Brenchley 113 and by Kelley. 114 Comparing the results of other investigators with ours, some interesting differences, as well as similarities, between them be- come evident. For example, we are in accord with most of the investigations above reviewed as favoring the existence of stimu- 96 Bull. Col. Agr., Tokyo Imp. Univ., 7, p. 635. 97 Jour. Roy. Agr. Soc. Eng., 64, p. 348. 98 Jour. Ind. Eng. Chern., 1, p. 533. 99 Agr. Gaz. N. S. Wales, 21, p. 219. io« Jour. Roy. Agr. Soc. Eng., 44, p. 348. ioi Compt. Rend., etc., 124, p. 1032. 102 Philippine Agr. and Forester, 1, p. 89. 103 Flora, 91, p. 264. ioi Bull. Col. Agr., Tokyo Imp. Univ., 5, p. 467 ; 6, p. 135. 105 Bull. Col. Agr., Tokyo Imp. Univ., p. 6. 125. iogBuII. Col. Agr., Tokyo Imp. Univ., 6, p. 137. 10? Bull. Col. Agr., Tokyo Imp. Univ., 7, p. 635. los Bull. Imp. Cent. Agrie. Exp. Sta., Japan, 1, p. 37. i"9 Jour. Col. Agr., Tokyo Imp. Univ., 1, p. 207. no Jour, fiir Lanciw., 55, p. 289. in 6° Cong. Internat. Chem. Appl. Roma, 4, p. 14. 112 Bot. Gaz., 55, p. 409. us Inorganic plant poisons and stimulants, Cambridge, 1914. in Hawaii Agr. Exp. Sta., Bull. no. 26. 546 University of California Publications in Agricultural Scie7ices [Vol. 1 lation by manganese of the growth of barley so far as the first crop on the soil in question is concerned. In the case of the second crop, however, a depression in yield of considerable mag- nitude is induced by MnS0 4 and a stimulation produced by MnCl, in the higher concentrations of the salt, while the lower ones depress the yield like MnS0 4 . In the third crop, as we have already seen, there is a practical disappearance of all toxic effects in both of the manganese series which we had under observation, and taking the place of the former toxic effects we find marked stimulating effects. The indication is therefore that in general our results are in accord with those of the investi- gators cited above who attributed to manganese stimulating effects for plants. ADDITIONAL INVESTIGATIONS Nitrification Earlier experiments by P. S. Burgess" • and the senior author had demonstrated the stimulating effects of CuS0 4 , FeS0 4 , ZnS0 4 , and PbS0 4 on nitrification in soils. We were therefore led to wonder whether much, if not all, of the stimulation ex- erted on the higher plants by most of the salts in the first crop was due to the increase in the available supply of nitrogen there through the effects of the salts. Accordingly, tests of the nitrify- ing powers of the soils in a number of the pots in every series were made by the usual laboratory methods employed for such purposes. Dried-blood nitrogen was used as the nitrifiable material at the rate of 1 per cent of the dry weight of the green- house soil. Lack of space forbids the presentation here of the large amount of data collected on the subject now under con- sideration. We may, however, refer to the striking features thereof, owing to their undoubted connection with the cause or causes of the stimulating effects above noted. In the second crop of the copper series in the greenhouse soil the nitrifying power was from 10 per cent to 50 per cent greater in the "coppered" than in the "uncoppered" soil. In the third crop, which, it us Univ. Calif. Publ. Agr. Sci., 1, p. 127. 1917] Lipman-Gericlce : Smelter Wastes and Barley Growth 547 will be remembered, was grown one year after the second and last copper application had been made, the increases in the nitrifying powers of the treated soils were from 33 per cent to 100 per cent greater than in the control soils receiving no copper. In a gen- eral way the highest concentrations of CuS0 4 gave the largest increases in nitrifying power in the second crop, but in the third crop there was more or less irregularity in that regard and the smaller concentrations appeared to be as effective as the larger. In the case of the zinc series, determinations of the nitrifying powers of the different soils were made after the third crop only. In that case also, the nitrifying power was increased by appli- cations of ZnS0 4 equivalent to 200, 600, and 1000 p. p. m. The increases, however, were much smaller than in the case of the CuS0 4 and varied from 3 per cent to 16 per cent at the different concentrations, the most favorable concentration being 600 p. p. m. An important difference exists between the CuS0 4 and the ZnS0 4 series in that all the concentrations of the former which were employed increased the nitrifying powers of the soil in the third crop to some extent, while only the concentra- tions just given were instrumental in imparting such a stimulus in the case of the latter salt. Iron behaved very similarly to zinc in most respects so far as the soil's nitrifying powers were con- cerned, and 0.2 per cent, 0.4 per cent, 0.6 per cent, and 0.8 per cent were tbe range of concentration of FeS0 4 corresponding to those named for ZnS0 4 above. One difference between iron and zinc in their influences on nitrification in the greenhouse soil is that the former does not seem to have been appreciably toxic in any concentration, even though as much as 2 per cent FeS0 4 was employed, whereas the latter, as we have already seen, markedly depressed the soil's nitrifying power when used in excess of 0.1 per cent of the dry weight of the soil. Like ZnS0 4 and FeS0 4 , PbS0 4 was tested as to its effect on nitrifica- tion after the third crop only. Under those conditions it gave, however, very different resints from the other salts, since no stimulation to nitrification was noted at all, no matter what amounts of PbS0 4 were employed. On the other hand, while PbS0 4 was throughout slightly toxic to nitrification under the 548 University of California Publications in Agricultural Sciences [Vol. 1 conditions named, the toxicity seemed to be about the same with the larger as with the smaller concentrations of PbS0 4 employed. The manganese salts were tested in the first crop only, in connection with their powers to affect nitrification. The follow- ing were the results : MnS0 4 was not toxic under the conditions named in any of the concentrations in which it was employed, 0.6 per cent being the highest. It appeared to be very slightly stim- ulating at all concentrations. In the case of MnCl, we find marked toxicity to nitrification at concentrations in excess of 0.4 per cent, and very distinctly toxic effects at concentrations in excess of 0.15 per cent. On the other hand, we also note that nitrification was stimulated by the following concentra- tions: 0.05 per cent, 0.1 per cent, and 0.15 per cent. The stimu- lation was very marked only in the case of the latter two con- centrations and was very much in excess of that induced by MnS0 4 at any concentration. The nitrifying powers of the Oakley blow sand employed in one copper series, which is described above, were also deter- mined. Marked stimulation to the nitrifying power of the soil was noted at concentrations of CuS0 4 equivalent to 100 p. p. m., 200 p. p. m., and 300 p. p. m., the first two being most marked. Ammonium sulfate was employed as the nitrifiable material. Amounts of CuS0 4 in excess of 300 p. p. m. were decidedly toxic, and very little or no nitrification occurred in the soil containing more than 700 p. p. m. CuS0 4 . While there is considerable discrepancy in the correlation of the effects of the different salts on barley growth and on the nitrifying bacteria, there appears to be a general relation, at least, between the stimulating effect exerted by a salt on the nitrifying flora and its effect on the barley plant. The serious irregularities which seem to militate at present against the definite establishment of such a relationship based on our data can undoubtedly be explained on the basis of certain factors like the residual nitrate supply in soils and the differences in its distribution throughout the soil mass which of course must exist. While therefore we make no attempt to assert that the stimu- lating effects and perhaps the toxic effects to barley exhibited by 1917] Lipman—Gericke : Smelter Wastes and Barley Growth 549 the salts here under discussion are to be accounted for by their effects on the nitrifying- flora and hence on the available nitrogen supply, we do believe that the latter is one of the few important factors — perhaps the most important — involved in the problem of explaining stimulation of plants in soils particularly, and possibly also, to some extent, the toxicity of salts in soils. That the effects of the salts on the nitrifying powers of the soils here studied are not the exclusive cause of the phenomena above dis- cussed, we can probably believe with confidence. The total quantities of citric acid-soluble phosphoric acid and potash in soils have been found by us to be augmented through the action of the metallic sulfates in question, and we are also aware of the possible inhibiting effects of those salts for certain factors which may be inimical to the proper development of the soil bacteria. In addition, there can be no question about the profundity of the changes in the soil's physical condition induced by any metallic sulfate and about the effects which follow in its wake. Most notable of all facts in that connection is the fluffy and pulverulent condition of the soils treated with ferrous sulfate, due undoubtedly to the formation of hydrated ferric oxide and other similar compounds. Special studies (unpublished) carried out by Mr. H. H. Coolidge on the soils of the ferrous-sulfate series, showed that the treatment of the soil reduced its power to raise water to a certain point, while at first allowing it to raise it faster; that the hygroscopicity of the soil was reduced; that its total water-holding power and its water-retentiveness were diminished; that its percolation power was increased; that its moisture-equivalent was diminished. Mr. Coolidge also found that, contrary to the effects of CuS0 4 and some of the other sulfates, the soil's water-soluble phosphorus and potassium were very much reduced in quantity by treatment with FeS0 4 . Dif- ferent and numerous though these effects be, there can be little question that they must influence, to some degree at least, the soil's nitrifying power. A further discussion of this phase of the problem is, however, impossible at this time and must await consideration in connection with some of our other studies. 550 University of California Publications in Agricultural Sciences [Vol. 1 Nitrogen Content of the Grain It appeared of interest, in view of the foregoing, to determine to what extent the soil's nitrate content, which was high through- out, had influenced the nitrogen content of the dry matter. We therefore determined the nitrogen content of the grain harvested in a number of the series so as to obtain some idea of the direc- tion taken by the effects of the nitrates, if any were exerted. As a result of these analyses it was found that in the second crop of the copper series the nitrogen content of the grain was in the absolute from 0.14 per cent to 0.57 per cent higher in the case of that grown on the "coppered" soil than in that grown on the control soils. In the third crop of the copper series the nitrogen content was from 0.05 per cent to 0.38 per cent higher in the grain from the treated soils than in that from the untreated soils. In the case of the second crop of the zinc series, the nitrogen content of the grain was from 0.06 per cent to 0.64 per cent higher in the grain of the treated than in that of the untreated soils. In the third crop of the zinc series, the corre- sponding figures ranged from nothing in one case, in which the lowest concentration of ZnS0 4 was used, to 0.42 per cent. Simi- larly in the case of the iron series, the range was from nothing to 0.68 per cent in the second crop, and from 0.22 per cent to 0.50 in the third crop. No determinations were made in the case of the lead series, but analyses were carried out in the case of the second crop of the potash alum series which indicated that the grain of the treated soils was in most cases only very slightly richer in nitrogen than that from the untreated soils, and that the maximum increase did not surpass 0.09 per cent. On the whole, and leaving the potash alum out of consider- ation, it seems that one of the results of stimulation of the barley plant by the metallic sulfates in question was the increase in the nitrogen content of the grain. At all concentrations of all the salts tested, with only one or two exceptions, the grain grown on the treated soils was richer in nitrogen than that on the untreated soils. That this fact should be referable primarily to the increased vigor of the nitrate formation in the treated 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 551 soils induced by the presence of the salts appears to the writers rational and justifiable. However that may be, there can be no question that even in the second and third crops on the soil under examination the nitrogen content of the grain shows its superiority in the case of the treated soils as against the un- treated soils. If this should prove true on soils in general, and there is strong likelihood that it will, should it not offer us a method for increasing the nitrogen content of our grain, a prob- lem which has for some time been agitating agronomists and flour producers in California? While, as has been indicated by other investigators, a high nitrogen content of grain may not necessarily imply a high gluten content of the flour, the latter being the consummation anxiously sought, it is at least likely that the generally higher nitrogen content of grain will also bring with it a higher gluten content. Since, moreover, our investigations indicate that small quantities of the metallic salts are as effective in inducing the enrichment of grain in nitrogen as the larger quantities, it is further possible that the means suggested of raising the gluten content of grain may prove to be a very inexpensive one. Absorption of Metals by Soil and Plant In discussing such problems as the one which forms the subject here, the technical chemist will frequently ask to what extent plants will absorb such metals as have been studied by us. The literature on that topic is so rich in evidence that metals are readily absorbed, and in considerable quantity, by the plant that we did not deem it desirable to go at length into such an investigation with our harvested barley plants as a basis. We did, however, make analyses of a number of plants from pots receiving different treatments and also of the soils in some of the pots. We are therefore in a position to answer partly on the basis of our own data, the question above raised. On the subject of the absorption of metals by plants, the reader is referred for full and interesting discussions to Czapek, 116 > lie Biochemie der Pflanzen, Jena, 1905. 552 University of California Publications in Agricultural Sciences [Vol. 1 Pfeffer, 117 Midler, 11 * Lehmann, 119 and Brenehley. 120 In our analyses both grain and straw were examined, and copper and zinc only were determined. These were both determined electro- lytically. Unlike Vedrodi, 121 we could find nothing more than traces of copper or zinc in the grain, but succeeded easily in obtaining definite quantities of those metals in the straw from some of the pots. In the first crop, from thirty-six to forty-three grams of straw were taken for analysis for copper, and, after ashing, the mineral residue was prepared for analysis for copper by the method above mentioned, straw from the pots receiving 100, 800, 1100, and 1200 p. p. m. CuS0 4 being employed. In the first case, the percentage of copper in the straw varied from nothing to 0.0006 per cent. In the second case, the percentage of copper was 0.0002. In the third case, it was 0.0033 per cent, and in the fourth case, 0.0044 per cent. In the pots receiving ZnS0 4 , there were chosen for analysis the straw produced in those receiving 100, 300, 500, 1000, 1100, 1200, 1300, and 1600 p. p. m. In the first case, the analysis showed the presence of zinc to the extent of 0.00036 per cent ; in the second, 0.0008 per cent; in the third, 0.003 per cent; in the fourth, 0.017 per cent ; in the fifth, 0.013 per cent ; in the sixth, 0.013 per cent ; in the seventh, 0.01 per cent ; and in the eighth, 0.012 per cent. In the cases of both zinc and copper the percentage of the metals absorbed by the barley plant was smaller than that reported as being absorbed by the plants studied by other investigators whose work is re- ferred to in the literature last cited. In general, it seems that up to a certain point increasing quantities of the metals added to the soil induce larger absorptions of metal by the plant, but beyond that point the addition of metals to the soil appears to be without effect in inducing further absorption. Tins seems to be particularly true in the case of the zinc. We do not desire, however, to draw any conclusions from the relatively meager data which we have gathered on the subject in question under 117 Pflanzenphysiologie, Leipzig, 1897 and 1901. us Ztschr. Pflanzenkrank., 4, p. 142. no Arch. Hyg., 27, p. 1. 120 Inorganic plant poisons and stimulants, Cambridge, 1914. i2i Cliem. Ztg., 20, p. 399. 1917] Lipman-Gericke : Smelter Wastes and Barley Growth, 553 the conditions here discussed. Since it is rare in nature that more than the lowest concentrations of copper and zinc here studied ever occur in soils suited to crop production, the ques- tion of the danger in the use by man and animals of plants absorbing copper is not a serious one, for with small quantities of copper and zinc present in the soil, very small quantities only are absorbed by the plant. It must be added here, morever, that we employed easily water-soluble salts, whereas in nature the compounds of the metais found are principally those of a very insoluble nature. The latter circumstance would perforce make impossible any large concentration of any metal in the soil solu- tion, and hence only small quantities could be absorbed by plants. We were interested also in obtaining an inkling as to the fate of the copper and zinc added to the soil after three seasons of plant growth thereon. Accordingly, several soils were chosen for examination. Pots receiving 600, 1800, 2000, and 3000 p. p. m. CuS0 4 gave the following results : In the first case all the copper added was recovered. In the second case 1750 p. p. m., instead of 1800, were recovered. In the third case all the cop- per was recovered, and in the fourth case 2875 p. p. m. were recovered, instead of 3000 p. p. m. In the case of zinc the pots receiving 800, 1700, and 2000 p. p. m. ZnS0 4 were studied. In the first case 750 p. p. m. were recovered. In the second case 1650 p. p. m. were recovered in one soil, and 1500 p. p. m. in another soil. In the third case only 1250 p. p. m. were recovered. These data indicate that in the case of copper, at least, the soil clings tenaciously to the metal ; and most of it, or nearly all of it, can be recovered from the soil even three seasons after it has been incorporated therewith, and three crops of barley grown in the interim. With zinc, there do appear to be losses. These may perhaps be explained in part by the larger amounts of zinc than copper absorbed by plants, and by the lesser accu- racy of the method for its determination as compared with that employed for copper. Twenty-gram samples of soil were em- ployed in all cases for obtaining the extracts which were an- alyzed, and it is therefore believed that the error involved in the analyses could not have been very large. 554 University of California Publications in Agricultural Sciences [Vol. 1 GENERAL AND PRACTICAL CONSIDERATIONS The practical as much as the theoretical point of view in- spired these investigations. In a time such as this, when the smelter question is of great significance in agricultural districts and when outcries against the damage caused by both smelter fumes and solid smelter wastes are most insistent, it appeared to us that the moment had arrived for wholly disinterested in- vestigators to examine into it. Our experiments as described in this paper have dealt, in the main, with the effects on barley growth in three successive crops of the metals which would be likely to be deposited in the vicinity of smelters and gradually washed down into sources of irrigation water for the territory lying below the smelter plants. Despite the fact that we have used much more soluble forms of the so-called toxic salts than are likely to occur under the conditions just described, and de- spite the fact that we have employed both large and small amounts of these salts, we are unable to read into our results any serious danger to agriculture from the solids of smelter wastes as they may be transported to cropped lands by irrigation water. In making this statement we are not unmindful that very small areas occur 122 near the smelter plants in which the tailings may be carried down by streams and deposited on land in large quantities. These may, for example, carry enough of the toxic heavy metals to render land poor in producing capac- ity. But in the first place the most prejudiced persons will not claim that such affected areas of agricultural land are more than negligible quantities when the question is considered in the large ; in the second place, even under conditions so extreme, none but the most biased will deny that proper methods of man- agement can be made to render innocuous any harmful effects which the tailings in question may be potentially capable of exerting. These methods of management are clearly indicated and include the impounding of water carrying tailings or the passage of stream water through screens which will separate out is 2 See E. H. Forbes, ' ' Certain effects under irrigation of copper com- pounds upon crops," Univ. Calif. Publ. Agri. Sei., 1, no. 12, 1917. 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 555 the tailings, and, in the case of the land which is already affected, the use of organic matter. The indications of our experiments are that a year or two of fallowing will usually correct the difficulty. We are therefore obliged to reaffirm the position taken by Lipman and Wilson 123 to the effect that there seems to be little danger in store for our agricultural lands in the metallic resi- dues which are deposited by smelters in their vicinity and from their idtimate solution in small degree in potential irrigation water-supplies which may be subsequently transported to farm lands. On the contrary, we give evidence above that so far from being toxic to barley plants, small amounts of the metals studied may be distinctly stimulating to them. While this is more strictly true in the case of some metals than of others, it appears none the less to be so. Moreover, in cases in which toxicity is effected by the application of any of the metallic sul- fates named, it is usually very slight, even when large quantities of the salts are employed. While we have experimented in this series of investigations only with barley, evidences given hy ourselves and by others who are above cited, indicate that a number of other plants behave similarly to barley, if not exactly like it. Prom the practical standpoint, therefore, we cannot see that any other conclusion can be reached than that we may virtually ignore any deleterious effects which may be urged against the metals of smelter wastes which are here discussed. We use the word ' ' practical ' ' here advisedly, because if solution instead of soil cultures were taken as a criterion, our standard of judgment would not be practical. Whatever may be said about soil cultures, one must admit that they approximate most closely of any greenhouse or laboratory methods the natural con- ditions under which crops grow. We cannot see that any other culture than one which at least offers a solid substratum to the plant may be regarded as valid in the determination of whether or not salts like those here under consideration are, under the conditions of the smelter and its vicinity, a menace to plant growth. 123 Bot. Gaz.. 55. no. 6. p. 409. June. 1913. 556 University of California Publications in Agricultural Sciences [Vol. 1 To all this, however, there must be added some other con- siderations. One of them serves to qualify, in some measure at least, the remarks made above, and the other to supplement them. While the metals studied by us do not seem to have given evi- dence, under the conditions of our experiment, of any serious injury to barley, a non-metal, arsenic, has given marked evidences of toxicity to barley under similar conditions. Arsenic, being found frequently in conjunction with the other elements in the vicinity of smelters, is necessarily a subject worthy of attention. Our results with its use in soil cultures are not yet ready to be reported, but we hope sometime in the near future to publish them. Suffice it to say now that such compounds of arsenic as arsenic trisulfide and Paris green have proved to be extremely toxic to barley in both heavy and light soils, while lead arsenate has proved to be only slightly toxic. Whether or not arsenic oxide, which is the form to be expected in lands in the vicinity of smelters, will act similarly remains to be shown by further experiments which are now being planned by us. We are constrained to add to the foregoing that we have borne in mind the difference in the effects produced on a toxic material by the change in a soil's constitution. Indeed, our experiments with copper in three widely different types of soil testify to that fact; and while we have found marked differences in the degrees of stimulation and toxicity of copper in the differ- ent soil types, all of the latter appear to have given both stimu- lation and toxicity. Even in the sandy soil in which the toxicity of CuS0 4 became manifest at the lowest concentration for any of the types of soil studied, as much as 0.03 per cent of CuS0 4 of the dry weight of the soil still acted as a stimulant to barley. Considering that CuS0 4 is an easily water-soluble salt, it would be reasonable to expect that such compounds as Cu(OH),.CuCO ;t , which are the usual forms to be expected in soils near smelters, could be tolerated by plants in much larger quantities. If, as appears to us reasonable, we should be able to accept the data above offered by us, at least as tentative evidence that we have little to fear from the solids of smelter wastes in the contamination of our irrigation water-supply and therefore in 1917] Liyman-Gericke : Smelter Wastes and Barley Growth 557 injuring large areas of land, we have another interesting propo- sition to bring forward. L. T. Sharp and the senior author 124 have already reported preliminary pot experiments in evidence of the fact that H 2 S0 4 exerts a remarkable effect on alkali soil with the result of changing the latter from an unproductive state to a productive one. The probable reasons for this action are discussed in the paper referred to above. Suffice it to say here that field experiments which still remain unpublished amply confirm the pot experiments. If this should prove to be a more or less permanent effect on alkali soils which do not contain too high a percentage of salts (from 0.6 per cent to 0.8 per cent), then we could solve the other and really serious phase of the smelter question, namely, the smelter gases. Chemical engineers of note, including F. G. Cottrell of the Bureau of Mines, have often stated to the senior author that the chief reason that S0 2 fumes from the smelters are not made into H 2 S0 4 is because there would be no use for such tremendous quantities of that acid. If, however, we should be able to apply H 2 S0 4 to many alkali soils with good effect that objection would vanish. If, therefore, the smelters will only produce the acid cheaply enough, as they now seem inclined to do, we shall be able to banish much costly litigation, let the smelter industry develop untramelled, give the smelter companies compensation for oxid- izing the S0 2 , and last but not least, put large acreages of barren land into good crop-producing condition. This proposition sounds almost chimerical, but much thought and work on it have convinced us that it is well justified by facts, and we believe that the condition just described will speed- ily come to pass. We mention the S0 2 problem here only in passing, since much fuller discussion of our experiments with H 2 S0 4 on alkali soils is to appear in later papers. Suffice it to say, that we believe we have in it and in the experiments above discussed strong evidence of methods for controlling the smelter nuisance without injuring the industry or the farmer, and, besides, much evidence on the true effects of solids of smelter wastes on barley grown in soils. i2i Univ. Cal. Publ. Agri. ScL, vol. 1, p. 275. 558 University of California Publications in Agricultural Sciences [Vol. 1 THEORETICAL CONSIDERATIONS A few words may not be out of place here with regard to the mechanism of the action of the different salts employed in our experiments, be such action in the direction of stimulation or in that of toxicity. In the first place, the salts in question must exercise some effect on the cell of the root itself and, through it, on the whole plant. If this were not so, we should not obtain the stimulating as well as the toxic effects of a given salt in solution cultures, as well as in soil cultures. In the latter, we do of course obtain more definite evidence of stimulation than in the former, and for that reason we may claim with some justice, as we have above, that stimulation effects are chiefly attributable to some influence, not always the same, induced by the salt on the soil, rather than on the root of the plant. This does not, to be sure, deny the existence of the latter effect in soil cultures and particularly in solution cultures; but when the most marked stimulation occurs, it is rarely noted in the latter. We therefore believe it reasonable to suppose that we are dealing under such circumstances with an effect on the soil, rather than with one on the plant root. "What such salt effects on the soil may be like are explained above. It is not easy, however, to explain or even to speculate on an explanation of the effect of a salt directly on the plant root in the direction of stimulation. We have no unexceptionable evidence on the subject of com- pounds of copper, for example, with albuminoid material of living cells, and that increases the difficulty of accounting for observed facts of stimulation. It is nevertheless possible that stimulation of root cells by copper may be due to an effect of the latter in decreasing or increasing the permeability of the cell, or perhaps to the possible small content of iron in the copper compounds employed, the iron acting as one of the essential elements to cell development. Neither of these speculations at present appears to have value other than that of inducing fur- ther thought and discussion on the subject. So far as the toxic effects of salts on plants in solution cultures is concerned, noth- ing need be added here to the excellent discussions already given by Czapek and Pfeffer which are cited above, and by Hober. 125 125 Physikalische Chemie der Zelle und der Gewebe, Leipzig, 1914. 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 559 With regard to stimulation in soil cultures, there may be added here something which is not mentioned in the discussion above, namely, that the salts of the heavy metals may act with respect to oxydases as Loew 126 has claimed manganese does, augmenting their activity and thus preventing the accumulation of toxic materials in the soil. That such a catalytic effect does exist is, however, very doubtful in the light of present evidence. That other forms of catalytic effects may be exerted by such salts as those employed in our experiments is at least not impossible. SUMMARY The authors have been carrying on a series of investigations on the effects of CuS0 4 , ZnS0 4J FeS0 4 , PbS0 4 , MnS0 4 , MnCL, KA1(S0 4 ) 2 .12 H 2 0, and different forms of arsenic on the growth of barley. The experiments were carried out in paraffined earth- enware pots nine inches in diameter, greenhouse soil made up from clay adobe soil and barnyard manure being used prin- cipally. In the case of CuS0 4 , two other soils were used in addition to the greenhouse soil, namely, the Oakley blow sand and the Berkeley clay adobe. With the greenhouse soil the experiment continued for three successive crops of barley ; with the clay abode soil, for two crops; and with the blow sand for only one crop. The results of these experiments, which are set forth in the tables and discussion above, may be summarized and their significance indicated briefly as follows : 1. In the greenhouse soil, in the first crop CuS0 4 acts as a stimulant throughout from concentrations of 50 p. p. m. to 600 p. p. m. inclusive. When the roots are left out of consideration, it acts as a stimulant even to the highest concentration employed, viz., 1500 p. p. m. In the second crop CuS0 4 acts as a stimulant to both roots and tops up to and including 1800 p. p. m., and is without effect on the roots, while stimulating to tops even at 2800 p. p. m. Grain production is stimulated by CuS0 4 in the second crop practically throughout the series. 126 Flora, 91, p. 264. 560 University of California Publications in Agricultural Sciences [Vol. 1 In the third crop both root and top production are stimulated up to and including concentrations of CuS0 4 equivalent to 2200 p. p. m. Grain production is almost similarly stimulated. 2. In the clay adobe soil in the first crop straw, grain, and root production are all stimulated up to and including concen- trations of CuS0 4 equivalent to 800 p. p. m. In the second crop no stimulation takes place in the 100 and 200 p. p. m. concentrations, but in all higher concentrations, at least including that equivalent to 900 p. p. m. This holds for both straw and root production. 3. In the Oakley blow sand, only one crop being grown, CuS0 4 stimulates markedly grain production and slightly straw and root production at concentrations up to and including 300 p. p. m. CuS0 4 . 4. In the greenhouse soil in the ZnS0 4 series the first crop is stimulated both as to root and straw yields throughout at concentrations varying from 100 p. p. m. to 2000 p. p. m. ZnS0 4 . In the second crop stimulation to straw and root yields occurs at 200 p. p. m. ZnS0 4 , and marked stimulation to root yield without effect on straw yields up to 600 p. p. m. ZnS0 4 . Beyond that point slight toxicity sets in and is maintained almost uniformly throughout. In the third crop neither stimulation nor toxicity is apparent at concentrations of 200 p. p. m. ZnS0 4 , but concentrations in excess of the latter are distinctly toxic. 5. In the greenhouse soil in the FeS0 4 series, the first crop shows the stimulating effects of PeS0 4 throughout in concentra- tions varying from 0.1 per cent to 1 per cent. The straw yields are increased throughout and the root jdelcls slightly so up to and including the concentration 0.7 per cent FeS0 4 . In the second crop FeS0 4 stimulates straw production in concentrations varying from 0.2 per cent to 1 per cent inclusive. Grain production is only slightly and irregularly stimulated at the same concentration. Root production is affected similarly to the grain production. In the third crop concentrations from 1 per cent FeS0 4 up to and including 2 per cent are. markedly stimulating to straw and grain yields and very slightly effective in both directions in 1917] Lipman-GericTce : Smelter Wastes and Barley Growth 561 regard to root yields. Smaller concentrations than those men- tioned slightly depress straw and root production, but definitely stimulate grain production. 6. In the greenhouse soil in the PbS0 4 series, first crop, the straw production is depressed by about one-third the total amount produced in the control. The depression appears to be uniform at concentrations of from 200 p. p. m. to 1.500 p. p. m. PbS0 4 . Likewise, the root yields are depressed by even a greater figure (about 60 per cent), and again almost uniformly throughout. In the second crop the straw production is nowhere depressed in the entire series and is stimulated at concentrations of from 300 p. p. m. to 600 p. p. m. PbS0 4 as well as at scattering con- centrations in excess. Root production, on the other hand, is slightly depressed throughout. In the third crop the straw production is markedly stimu- lated at concentrations varying from 1000 p. p. m. to 2400 p. p. m. PbS0 4 , but slightly depressed at lower concentrations. Grain production is similarly affected, and the PbS0 4 remains without effect on the roots within the same limits of concen- tration. 7. In the greenhouse soil in the potash alum series the first crop shows stimulation to straw yields at all concentrations varying from applications of 300 pounds to 2000 pounds K 2 per acre. Root yields are stimulated at the lowest concentration named, but scarcely at all in the others. In the second crop the straw yields are again stimulated by the doubling of the potash alum application throughout the series. Relatively the stimulation is much greater than in the first crop. Grain production and root production are also mark- edly stimulated, the former at the smaller applications of potash alum and in other isolated instances, and the latter throughout. In the third crop the straw yield is markedly depressed throughout. The grain yields are slightly stimulated in some cases, and in the balance remain unaffected. The root yields are depressed similarly to the straw yields. 8. In the greenhouse soil in the MnS0 4 series the first crop is stimulated in regard to straw yields at all concentrations be- 562 University of California Publications in Agricultural Sciences [Vol. 1 tween 500 p. p. m. and 3000 p. p. m. MnS0 4 , but most markedly at 1500 p. p. m. The root yields are also markedly stimulated, but only at concentrations up to and including 1500 p. p. m. Beyond that concentration, root yields are more or less reduced. In the second crop the straw yields are stimulated at from 4000 p. p. m. to 6000 p. p. m. MnS0 4 , but markedly depressed at concentrations below 4000 p. p. m. The "rain yields are about equally depressed throughout, but not markedly. The root yields are depressed throughout the series rather markedly, the smallest depression occurring a1 concentrations of 2000 and 2500 p. p. m. MnS0 4 . In the third crop a stimulation is induced toward the pro- duction of straw, grain, and roots, the medium concentrations being most effective. Little or no evidence of toxic effects of MnS0 4 was observed. 9. In the greenhouse soil in the MnCl, series the first crop is markedly stimulated in si raw production at concentrations vary- ing from 500 to 1500 p. p. m. MnCL. Beyond the latter concen- tration, MnCl 2 becomes more and mure acutely toxic, until almost no straw is produced at 6000 p. p. in. MnCL. Root production is affected similarly to straw production, in a general way. In the second erop straw production is stimulated throughout except at the two lowest concentrations — 500 and 1000 p. p. m. respectively. Grain yields, however, are depressed almost throughout. The depression is relatively slighl (there being one case of stimulation) at concentrations varying from 500 p. p.m. to 3000 p. p. m. Above the latter concentration, the MnCL is markedly toxic to grain production. Root production is markedly depressed throughout. Like MnS0 4 , MnCL exerts a stimulating effect on the yields of straw, grain, and roots in the third crop. Again, Little or no evidence of a toxic effect was noted in this series. 10. Results are given on the effect of the salts used on the nitrogen content of the grain produced, on the nitrifying powers of the soils concerned, on the amounts of copper and zinc taken up by some of the barley plants in the different series; and 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 563 also correlations are drawn between some of these factors and the complete yields of dry matter. 11. Some practical and theoretical phases of the smelter question are discussed, and the evidence above given is employed to show that from the large practical standpoint the solids of smelter wastes cannot justly be considered a menace to agriculture. 12. Many other points of interest are discussed in connection with the smelter problem as a whole and with the results of our experiments. Transmitted September 7, 1916. 564 University of California Publications in Agricultural Sciences [Vol. 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 o *" •a ft O*£o" x —2 ~ — . o D Sr-T 50 50 100 100 200 200 300 300 400 400 500 500 600 600 700 700 800 800 900 900 21 1000 22 1000 23 1100 24 1100 25 1200 26 1200 27 1300 28 1300 29 1400 30 1400 31 1500 32 1500 33 Control 34 Control 35 Control •a* ?■£ gm. 47.8 37.8 43.5 32.0 47.9 36.5 41.6 39.5 37.2 40.8 38.2 35.2 46.5 47.5 38.7 41.0 50.7 40.0 51.2 40.2 44.6 42.5 35.8 42.3 40.0 42.5 38.4 40.8 42.8 33.9 37.2 38.1 31.5 31.2 34.8 CuS0 4 Set 3 be "3 ^ <** 2| -S a bn gm. gm. 42.80 37.75 42.20 40.55 39.00 36.70 47.00 39.85 45.35 45.70 43.55 39.05 41.25 40.10 38.35 37.65 32.50 TABLE Ho -First Crop — Greenhouse Soil ■H ^ flj V .M nl O .« * .SP-St: Ss-g-E -m & ®e g g 3 o> a 3 o) w>.5 £ " ■« m " m ■£ fc»^2 cSbJ __ **• o> «3 >> q> ^_ rt o Sit. ^s >- > h K S be ai ^ X >^ 1*1 52l |g >£ gm. gm. gm. gm. gm. 47.8 42.80 10.2 9.05 37.8 7.9 43.5 37.75 8.7 9.45 32.0 10.2 47.9 42.20 10.0 8.25 36.5 6.5 41.6 40.55 9.5 10.75 39.5 12.0 37.2 39.00 7.9 7.85 40.8 7.8 38.2 36.70 9.8 8.50 35.2 7.2 46.5 47.00 8.2 8.20 47.5 8.2 38.7 39.85 7.0 6.25 41.0 5.5 50.7 45.35 7.2 6.45 40.0 5.7 51.2 45.70 4.8 5.35 40.2 5.9 44.6 43.55 5.5 5.25 42.5 5.0 35.8 39.05 3.9 4.40 42.3 4.9 40.0 41.25 4.8 4.35 42.5 3.9 39.4 40.10 4.2 4.55 40.8 4.9 42.8 38.35 3.8 4.30 33.9 4.8 37.2 37.65 6.0 4.75 38.1 3.5 31.5 32.50 7.8 7.26 31.2 6.9 34.8 7.1 No E-i-o p. be 3 £ Q p rt ™ £1 IS <^2 gm. gm. 58.0 51.85 + 12.09 45.7 52.2 47.20 + 7.44 42.2 57.9 50.45 + 10.69 43.0 51.1 51.30 + 11.54 51.5 45.1 46.85 + 7.09 48.6 48.0 45.20 + 5.44 42.4 54.7 55.20 + 15.44 55.7 45.7 46.10 + 6.34 46.5 57.9 51.80 + 12.04 45.7 56.0 51.05 + 11.29 46.1 50.1 48.80 + 9.04 47.5 39.7 43.45 + 3.69 47.2 44.8 45.60 + 5.84 46.4 43.6 44.65 + 4.89 45.7 46.6 42.65 + 2.89 38.7 43.2 42.40 + 2.64 41.6 39.3 39.76 38.1 41.9 1917 I Lipman-Gerieke : Smelter Wastes and Barley Growth 565 TABLE lib CuSO^ Set — Second Crop — Greenhouse Soil CuS0 4 added to soil in parts per 1,000,000 o £ t> '3 S* £ M '3 is be £ eS g a s c3 *3 > Ho « £ „ bfi ^ ^ '3 -2 ss £ "S*C a) g s u u l. O A fcJD W *S o £ .5? "3 ed o ? * ej ^^ a — a> IS be ° — <* O) o 2 h x >s§ • «T3 o H oes oj g 3 CO >>OJ u n > "Jos O be w "3 o £2 OJ t- o OJ U > < o O ? [j o _ g 3 C3 a T3 O h fi .£? =* '53 - 'd ■sCg « a K aj .2 -w > C3 > Wi < O C3 o 2 *S O £g '53 03 o i 1 ° P C3 o "3 a -§ ■E " a)" p. — . o> o3 > ™S £ <;3g gin. 9.5 gm. 8.75 gm. 0.80 gm. 1.10 gm. 10.30 gm. 9.85 + 1.93 8.0 1.40 9.40 4.0 3.50 1.20 1.00 5.20 4.50 —2.42 3.0 .80 3.80 10.0 8.75 1.40 1.05 11.40 9.80 + 1.88 7.5 .70 8.20 6.5 7.75 1.20 1.55 7.70 9.30 + 1.38 9.0 1.90 10.90 7.1 8.65 .85 1.00 7.95 9.65 + 1.73 10.2 1.15 11.35 9.7 8.60 1.00 .92 10.70 9.52 + 1.60 7.5 .85 8.35 7.0 8.75 .65 .75 7.65 9.50 + 1.58 10.5 .85 11.35 8.5 7.95 1.00 .80 9.50 8.75 + 0.83 7.4 .60 8.00 9.8 9.00 .85 1.02 10.65 10.00 + 2.10 8.2 1.20 9.40 4.3 3.75 .45 .52 4.75 4.42 —3.50 3.5 .60 4.10 6.0 5.90 .70 .70 6.70 6.60 —1.32 5.8 .70 6.50 3.5 3.50 .20 .20 3.70 3.70 4. 22 7.4 7.20 .95 .73 8.35 7.92 7.0 .50 7.50 568 University of California Publications in Agricultural Sciences [Vol. 1 TABLE Ulb CuSOj Set — Second Crop — Adobe Soil o b «2 — 2 3 •- o 100 100 200 200 300 300 400 400 500 500 600 600 700 700 800 800 900 900 19 1000 20 1000 21 1200 22 1200 23 1500 24 1500 25 2000 26 Control 27 Control 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 t> % gm. 6.5 6.0 7.5 7.5 9.0 8.7 6.0 6.5 8.5 7.5 8.8 10.0 10.2 8.5 10.5 9.2 9.5 11.7 8.8 7.0 7.2 7.3 10.0 8.0 5.1 7.0 7.5 t- r< be C S <° "S'3 tm gm. gm. 6.25 7.50 8.85 6.25 8.00 9.40 9.35 9.85 10.60 7.90 7.25 9.00 5.10 7.25 ta.5 •<< OJ rl ^ _, >» « Eh =3 .Sf u § 5 £ cs 1* «8 fJ fli fl H fcfi B W FH ^ h. O *S £2 p* > ^ f so Eh-O 0, .5? § oj-O p, IS 111 .H so 3 'S .t3 p eg £ o :£ *-£ S IS 1 100 gm. 4.78 gm. 4.52 gm. 1.72 gm. 1.79 gm. 6.5 gm. 6.30 gm. 2.10 gm. 1.85 gm. 8.60 gm. 8.15 4-2.15 2 100 4.25 1.85 6.1 1.60 7.70 3 200 3.68 3.43 2.32 2.52 6.0 5.95 2.70 2.40 8.70 8.35 + 2.35 4 200 3.17 2.73 5.9 2.10 8.00 5 300 3.90 3.80 2.30 2.40 6.2 6.20 1.30 1.10 7.30 7.20 + 1.20 6 300 3.70 2.50 6.2 .90 7.10 7 400 2.40 2.40 1.60 1.60 4.0 4.00 .55 .55 4.55 4.55 —1.45 8 400 .... 9 500 2.90 2.75 1.20 1.30 4.1 4.05 .15 .15 4.25 4.20 —1.80 10 500 2.60 1.40 4.0 .15 4.15 11 600 2.85 3.53 2.35 2.67 5.2 6.20 5.20 6.20 + 0.20 12 600 4.20 3.00 7.2 7.20 13 700 2.40 2.80 1.30 1.40 3.7 4.20 3.70 4.20 —1.80 14 700 3.20 1.50 4.7 4.70 15 800 1.20 1.20 1.2 1.20 .10 .10 1.30 1.30 —4.70 16 800 .... 17 900 .20 .20 .2 .20 .20 .20 —5.80 18 900 .... 19 1000 .... 20 1000 .... 21 1200 22 1200 23 Control 2.80 3.40 1.30 1.30 4.1 4.05 1.60 1.95 5.70 6.00 24 Control 4.00 4.0 2.30 6.30 570 University of California Publications in Agricultural Sciences ["Vol. 1 ZnS0 4 Set- S S- cTS " Co - o 11 P^ CO 2 .5? '3 ■s « 8 • « < o o 2 . MO '3 C3 gm. gm. gm. 1 100 38.9 37.45 2 100 36.0 3 300 38.9 36.55 4 300 34.2 5 500 37.4 39.10 6 500 40.8 7 700 46.8 40.30 8 700 33.8 9 900 41.4 41.30 10 900 41.2 11 12 1100 1100 41.1 43.5 42.30 13 1200 42.2 41.40 14 1200 40.6 15 16 1300 1300 31.2 31.5 31.35 17 1400 36.7 34.85 18 1400 33.0 19 20 1500 1500 38.5 37.7 38.10 21 1600 37.0 36.00 22 1600 35.0 23 1700 35.8 36.80 24 1700 37.8 25 1800 38.7 38.10 26 1800 37.5 27 1900 43.8 41.90 28 1900 40.0 29 2000 31.0 35.60 30 2000 40.2 31 Control 30.2 33.40 32 Control 36.6 TABLE Va -First Crop — Greenhouse Soil 2 2 JA .bo s* g U h g .M bjD.5 £ ** w bC H to -£ W)M fch jib tnt.S: b» M hS g M 5-dg «flo -S-S »S "^ o E-< o cd <3 o rt p-h ""S © gm. gm. gm. gm. gm. 38.9 37.45 8.6 8.55 36.0 8.5 38.9 36.55 7.5 7.60 34.2 7.7 37.4 39.10 6.5 9.90 40.8 13.3 46.8 40.30 8.6 10.60 33.8 12.6 41.4 41.30 8.1 8.00 41.2 7.9 41.1 42.30 7.7 9.25 43.5 10.8 42.2 41.40 8.3 8.50 40.6 8.7 31.2 31.35 12.0 12.00 31.5 36.7 34.85 10.8 11.15 33.0 11.5 38.5 38.10 6.2 7.50 37.7 8.8 37.0 36.00 11.3 12.15 35.0 13.0 35.8 36.80 9.3 10.60 37.8 11.9 38.7 38.10 10.0 10.20 37.5 10.4 43.8 41.90 13.0 13.15 40.0 13.3 31.0 35.60 10.4 10.85 40.2 11.3 30.2 33.40 8.5 8.30 36.6 8.1 2 , be >- o t, t, E-i-d p. S C'g aj" 3 p, ^ o +- < o a - & .S?3.h &£'g 2 a, » ,„ ?Sa a-^P. £ m» £ « S »-!, "£-s « o _ a 3 ?-2 3 p £ 8 ZnS0 4 added tc soil in pai'ts pel 1,000,000 © 11 3 Ml *s Is v fe gj y « . £S% .SPSS , a 3 H os > — — > C4 U rt b, cb ■< o «s «4H O ■sg 1 g O ^ o > < o <»>6! ? « o — £ = "£ >■ o o t. M H-O ft be 3 cu^ a. 1- •- ■5"sa "a > St cj jy o ££■§ -J--3 o E- 1 c s "Sit. « '5 2 a ^ GS Sh « a 2 be n to g&s O he w £g an "as 60 ■» «a.= oC'g bD § '3 U.T3 <:^ a — - C3 S" O ^ J- ^ •aJ'-S S gm. gm. gm. gm. gm. gm. gm. 40.0 39.95 10.6 9.05 50.6 49.00 +8.20 39.9 7.5 47.4 39.7 35.45 6.0 7.20 45.7 42.65 + 1.85 31.2 8.4 39.6 43.7 40.30 7.0 9.45 50.0 49.75 + 8.95 36.9 11.9 48.8 41.0 39.90 6.3 8.65 47.3 48.55 + 7.85 38.8 11.0 49.8 34.0 35.25 9.2 8.40 43.2 43.65 + 2.85 36.5 7.6 44.1 38.5 39.10 9.7 8.50 48.2 47.60 + 6.80 39.7 7.3 47.0 28.2 36.30 13.4 9.60 41.6 45.90 +5.10 44.4 5.8 50.2 32.8 38.20 4.2 5.65 37.0 43.85 + 3.05 43.6 7.1 50.7 37.1 36.80 6.9 6.70 44.0 43.50 + 2.70 36.5 6.5 43.0 28.7 34.85 5.9 6.35 34.6 41.20 + 0.40 41.0 6.8 47.8 34.8 32.50 8.5 8.30 43.3 40.80 30.2 8.1 38.3 574 University of California Publications in Agricultural Sciences [Vol. 1 TABLE VI6 FeS0 4 Set — Second Crop — Greenhouse Soil 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 -§ as m ~ p. 0.1 0.1 0.2 0.2 0.3 0.3 0.4 0.4 0.5 0.5 0.6 0.6 0.7 0.7 0.8 0.8 0.9 0.9 1.0 1.0 be ? « ? £l gm. 11.20 6.47 9.90 6.75 9.30 5.50 9.45 6.82 21 Control 22 Control 23 Control gm. 2.60 7.73 6.50 6.45 6.50 4.50 4.55 5.48 be. 5 fe " w C3 ci _1 >. ^, 0^^3 a 3 o> o 3 ° £ . Q) . fl *f o to ^ a, -a p « £ 3 3 o« ° «, & re a g£2 >S C on bi «; o Bo« t, •< o gm. gm. gm. gm. gm. gra. gm. gm. gm. gm. 1 0.1 19.00 17.55 0.47 19.0 19.90 7.0 7.50 26.0 27.40 — 3.15 2 0.1 16.10 4.70 20.8 8.0 28.8 3 0.2 20.05 17.80 1.85 3.05 21.9 20.85 8.2 8.10 29.9 28.95 — 1.60 4 0.2 15.55 4.25 19.8 8.0 28.0 5 0.3 13.75 14.27 5.65 4.82 19.4 19.60 4.4 4.80 23.8 24.40 — 6.15 6 0.3 15.80 4.00 19.8 5.2 25.0 7 0.4 20.70 19.17 4.80 4.07 25.5 23.75 5.8 6.40 31.3 30.15 — 0.40 8 0.4 18.65 3.35 22.0 7.0 29.0 9* 0.5 34.80 25.87 4.05 34.8 27.90 4.0 6.75 38.8 34.65 + 4.10 10 0.5 16.95 4.05 21.0 9.5 30.5 11 0.6 14.45 13.87 4.55 4.12 19.0 18.00 5.0 5.40 24.0 23.40 — 7.15 12 0.6 13.30 3.70 17.0 5.8 22.8 13 0.7 25.62 23.31 4.40 4.10 30.2 27.50 6.2 8.75 36.4 36.35 + 5.85 14 0.7 21.00 3.80 24.8 11.5 36.3 15 0.8 31.90 27.41 2.60 3.23 34.5 30.65 6.0 8.15 40.5 38.80 + 8.25 16 0.8 22.93 3.87 26.8 10.3 37.1 17 0.9 28.90 21.52 2.30 4.57 31.2 26.10 6.7 7.00 37.9 33.10 + 2.55 18 0.9 14.15 6.85 21.0 7.3 28.3 19 1.0 20.10 27.60 8.90 7.40 29.0 35.00 9.7 8.95 38.7 43.95 +13.40 20* 1.0 35.10 5.90 41.0 8.2 49.2 21 Control 22.40 19.30 2.10 2.25 24.5 21.55 7.5 9.00 32.0 30.55 22 Control 16.20 2.40 18.6 10.5 29.1 * Failed to grow second crop. 576 University of California Publications in Agricultural Sciences [Vol. 1 TABLE Vila PbS0 4 Set — First Crop — Greenhouse Soil 1 2 3 4 5 6 7* 8 9 10 11 12 13 14 15 16 17 18 18 20 21 22 23 24 25 26 27 28 29 30 o u ■S id •3 S° m '-.2 200 200 300 300 400 400 500 500 600 600 700 700 800 800 900 900 1000 1000 1100 1100 1200 1200 1300 1300 1400 1400 1500 1500 Control Control SI > Z "5i& em. 16.5 25.5 19.5 23.1 21.3 23.1 18.4 22.2 24.4 24.0 23.2 26.8 17.0 26.8 30.3 22.0 21.5 18.2 28.5 21.9 26.0 23.8 27.9 25.0 18.2 17.8 26.7 34.8 25.2 u i* sua s« -3-3 tn gm. em- 21.00 21.30 22.20 18.40 23.30 23.60 21.90 28.55 21.75 23.35 23.95 25.85 21.60 22.25 30.00 s .5? '3 •£ SlO.5 >- U % M -SF"3*S 'Sd ^ & O a EH a 2 55 C3 t. a> a s CS >>« - - . p. cs =f 3 3 OS >^ a < a — Oi si > £,£_ « £ g t»»» -a. go Sr g g || ggg ft >h ;>« fc. << o Hfla 83 U ® a ^ hj) B to c3 >. a U U b. ".OS O bJC OT S % <~ O O 2 . bis *■• P ce u Oft. Ml g te C'O aj-O p. < o a — - t° £So 1 200 em. 16.20 gm. 15.10 gm. 2.30 gm. 2.30 gm. 18.5 gm. 16.25 gm. 8.0 gm. 8.00 gm. 26.5 gm. 24.25 — 4.32 2 200 14.00 1.4 8.0 22.0 3 300 15.70 17.45 2.30 2.30 18.0 19.75 7.2 7.15 25.2 26.85 — 1.67 4 300 19.20 2.30 21.5 7.1 28.6 5* 400 9.80 11.70 2.40 2.15 12.2 13.85 4.2 3.80 16.4 17.65 —10.92 6* 400 13.60 1.90 15.5 3.4 18.9 7 500 24.30 24.35 1.90 2.15 26.2 26.50 6.9 7.95 33.1 34.45 + 5.88 8 500 24.40 2.40 26.8 7.0 33.8 9 600 24.70 24.60 24.7 24.60 5.7 7.75 30.4 32.35 + 3.78 10 600 24.50 24.5 9.8 34.3 11 700 20.90 20.25 4.00 4.00 24.9 22.75 9.5 9.15 34.4 31.90 + 3.33 12 700 19.60 19.6 8.8 28.4 13 800 22.35 21.17 2.65 2.65 25.0 22.70 5.9 6.10 30.9 28.60 + 0.03 14 800 20.00 20.0 6.3 26.3 15 900 18.80 20.67 5.60 4.27 24.4 24.95 5.8 7.80 32.2 33.75 + 5.18 16 900 22.55 2.95 25.5 9.8 35.3 17 1000 19.72 20.63 2.48 2.82 22.2 23.45 7.0 7.00 29.2 30.45 + 1.88 18 1000 21.55 3.15 24.7 7.0 31.7 19 1100 29.22 25.37 4.67 3.06 33.9 28.45 9.0 6.60 40.5 35.05 + 6.48 20 1100 21.55 1.45 23.0 4.2 29.6 21 1200 21.05 21.07 3.25 3.22 24.3 24.30 7.0 7.25 31.3 31.55 + 2.98 22 1200 21.10 3.20 24.3 7.5 31.8 23 1300 20.77 18.76 5.03 3.14 25.8 21.90 6.8 5.90 31.6 27.80 — 0.77 24 1300 16.75 1.25 18.0 6.0 24.0 25 1400 17.00 17.45 5.00 4.40 22.0 21.85 7.0 8.00 29.0 29.85 + 1.28 26 1400 17.90 3.80 21.7 9.0 30.7 27 1500 16.20 18.90 1.50 1.50 17.7 19.65 4.2 6.10 23.8 25.75 — 2.82 28 1500 21.60 21.6 8.0 29.6 29 Control 16.50 18.65 2.10 2.25 18.6 19.77 10.5 8.80 29.1 28.57 30 Control 22.10 2.40 24.5 8.2 32.7 31 Control 14.50 14.5 7.5 22.0 32 Control 21.50 21.5 9.0 30.5 * Plants partly damaged by mice. 1917] Lipman-Gericke : Smelter Wastes and Barley Growth 579 TABLE Villa Potash Alum .Set — First Crop — Greenhouse Soil u J3 d » 2 M s'sS- ^* ^S ^ c PncSo t>10 ■< O P-to gm. gm. gm. 1 300 38.8 39.20 2 300 39.6 3 400 38.4 38.30 4 400 38.2 5 500 29.6 35.90 6 500 42.4 7 600 38.8 39.50 8 600 40.2 9 700 36.3 36.50 10 700 36.7 11 800 34.4 33.45 12 800 32.5 13 900 36.8 39.40 14 900 42.0 15 1000 34.2 36.80 16 1000 39.4 17 2000 35.5 34.95 18 2000 34.4 19 Control 31.5 32.50 20 Control 31.2 21 Control 34.8 s 5s ? d M.S o3 o3 h U S> Ml < o « "> 2 '3d3 fe " a _ h» -•° o Hoes S Mu g 2£-£ o be to II 2 o P rt w — 3 = 2 8 faC rj '3 .a Oi"= p. «i o a Average total difference over control gm. gm. 38.8 gm. 39.20 gm. 6.6 gm. 9.15 gm. 45.4 gm. 48.35 + 8.59 39.6 11.7 51.3 38.4 38.30 8.5 7.80 46.9 46.10 +6.34 38.2 7.1 45.3 29.6 35.90 7.7 7.00 37.3 42.90 + 3.14 42.4 6.3 48.5 38.8 39.50 7.5 7.85 46.3 47.35 + 7.59 40.2 8.2 48.4 36.3 36.50 5.5 7.15 41.8 43.65 +3.89 36.7 8.8 45.5 34.4 33.45 5.7 5.70 40.1 39.15 —0.61 32.5 .... 38.2 36.8 39.40 6.8 6.85 43.6 46.25 + 6.49 42.0 6.9 48.9 34.2 36.80 8.0 7.65 42.2 44.45 +4.69 39.4 7.3 46.7 35.5 34.95 6.1 5.20 41.6 40.15 + 0.39 34.4 4.3 38.7 31.5 32.50 7.8 7.26 39.3 39.76 31.2 6.9 38.1 34.8 7.1 41.9 580 University of California Publications in Agricultural Sciences [Vol. 1 TABLE VIII& Potash Alum Set — Second Crop — Greenhouse Soil Potash Alum added at rate of K„0 per acrs o ■!* "3 s P- to '3 tog s| o 5.5 P d u u ? « V. « a s be » w h t- 5. >2l ■< o"c3 O £ '3 o £2 .a M.2 ^ o « u o S , M 3 ir -« *5 ° be > ■*£t3PH ,? -a «-, fe-E j; *h > fj s ■■ woo p-ta < o >> M > CD «ii > J2 ■ssS ® a ^ c3 >» g o)' e p. CD R ^ cS > IS ® e « p p ^ - a gm. 14.3 gm. 16.90 gm. 8.2 gm. 7.80 gm. 22.5 gm. 24.70 —2.73 19.5 7.4 26.9 14.5 14.75 7.3 6.65 21.8 21.40 —6.03 15.0 6.0 21.0 13.2 13.60 5.2 4.85 18.4 18.45 —8.98 14.0 4.5 18.5 14.2 16.85 6.0 5.50 19.7 22.35 —5.08 19.5 5.0 24.5 12.0 11.25 5.7 6.60 17.7 17.85 —9.58 10.5 7.5 18.0 15.5 15.35 7.5 7.50 23.0 22.85 —4.58 15.2 7.5 22.7 12.9 14.15 6.7 6.45 19.6 20.60 —6.83 15.4 6.2 21.6 14.6 14.60 5.2 4.60 19.8 19.20 —8.23 14.6 4.0 18.6 16.0 18.00 7.4 6.50 23.4 24.50 —2.93 20.0 5.6 25.6 21.5 18.20 8.2 9.23 29.7 27.43 18.6 9.0 27.6 14.5 10.5 25.0 582 University of California Publications in Agricultural Sciences [Vol. 1 TABLE IXo MnS0 4 Set — First Crop — Greenhouse Soil MnS0 4 add soil in part 1,000,000 o tog 03 ? >. o £ _ .to-2 S 03 fS to 1 500 gm. 47.5 gm. 51.00 gm. 2 500 54.5 3 1000 54.3 54.15 4 1000 54.0 5 1500 56.8 61.90 6 1500 67.0 7 2000 45.6 44.40 8 2000 43.2 9 2500 49.2 46.70 10 2500 44.2 11 3000 42.0 44.75 12 3000 47.5 13 3500 45.7 40.75 14 3500 35.8 15 4000 39.0 41.75 16 4000 44.5 17 4500 43.0 43.00 18 4500 43.0 19 5000 42.0 45.50 20 5000 49.0 21 5500 42.8 39.10 22 5500 35.4 23 6000 41.0 45.85 24 6000 50.7 25 Control 41.1 41.46 26 Control 43.0 27 Control 40.0 •5 S2S a a S S 3 to.2 £ H 00 > ^ o^,5 •<1 O E-l o C5 gm. gm. 47.5 54.5 54.3 54.0 56.8 67.0 45.6 43.2 49.2 44.2 42.0 47.5 45.7 35.8 39.0 44.5 43.0 43.0 42.0 49.0 42.8 35.4 41.0 50.7 41.4 43.0 40.0 P cS U J- *-.' £ I"- <; o os o .c bt to £2 to '5 & a> to.2 < o O It. __ c = 03 1 ™T3 2-~' 2 & 5 to s v^ p. It* K > .*" * - r S — 0> IS toS„ « & g gm. 51.00 gm. 11.5 12.5 gm. 12.00 gm. 59.0 67.0 gm. 63.00 + 10.87 54.15 11.5 13.0 12.25 65.8 67.0 66.40 +14.27 61.90 13.5 11.5 12.50 70.3 78.5 74.40 +22.27 44.40 7.6 9.0 8.30 53.2 52.2 52.70 + 0.57 46.70 9.5 9.7 9.60 56.2 53.9 55.05 + 2.92 44.75 10.5 7.5 9.00 52.5 55.0 53.75 + 1.62 40.75 9.2 9.7 9.45 54.9 45.5 50.20 — 1.93 41.75 8.0 7.5 7.75 47.0 52.0 49.50 — 2.63 43.00 10.7 9.0 9.85 53.7 52.0 52.85 + 0.72 45.50 8.0 7.0 7.50 50.0 56.0 53.00 + 0.87 39.10 6.5 7.1 6.80 49.3 42.5 45.90 — 6.23 45.85 8.0 6.7 7.35 49.0 57.4 53.20 + 1.07 41.46 12.5 11.0 8.5 10.66 53.9 54.0 48.5 52.13 1917] Lipman-Gericlce : Smelter Wastes and Barley Growth 583 TABLE IXb MnSO. Set — Second Orop — Greenhouse Soil 2 * n p. •3* J3 .a '3 s * ° ■£ M 2 "2 M.E nag 1 2 £» '£ 2 "" gm. gin. gm. gm. 1 500 14.05 14.05 3.45 3.45 2 500 14.05 3.45 3 1000 16.50 19.45 3.50 3.50 4 1000 22.40 3.50 5 1500 13.40 12.95 4.40 4.70 6 1500 12.50 5.00 7 2000 13.55 12.94 4.25 3.72 8 2000 12.32 5.18 9 2500 11.77 11.89 3.73 3.87 10 2500 12.00 4.00 11 3000 13.33 13.32 4.67 4.19 12 3000 13.30 3.70 13* 3500 7.50 10.24 3.30 4.41 14 3500 12.97 5.53 15 4000 14.67 15.83 2.33 2.33 16 4000 17.00 17 4500 12.02 16.80 4.98 4.20 18 4500 21.58 3.42 19 5000 13.56 16.53 4.64 4.64 20 5000 19.50 21 5500 18.20 18.20 2.50 2.50 22 5500 23 6000 21.70 24.03 1.30 .92 24 6000 26.36 .54 25 Control 13.08 13.71 5.05 5.16 26 Control 12.87 4.13 27 Control 15.17 6.31 * One plant died. -SP'S'S ~T3 o ^ „, .if* a P -, ta S-, u > > o O t< H H-o p. J3 g .5? 3 4)^ P. « * 3 "£ 2 «j o a _ 0) IS 2 II gm. gm. gm. gm. gm. gm. 17.5 17.50 10.5 10.25 28.0 27.75 —4.39 17.5 10.0 27.5 20.0 22.45 7.5 9.25 27.5 26.70 —5.44 24.9 11.0 25.9 17.8 17.65 7.5 6.75 25.3 24.40 —7.74 17.5 6.0 23.5 17.8 17.65 10.7 12.00 28.5 29.65 —2.49 17.5 13.3 30.8 15.5 15.75 12.5 11.60 28.0 27.35 —4.78 16.0 10.7 26.7 18.0 17.50 9.7 9.35 25.7 25.75 —6.38 17.0 9.0 26.0 10.8 14.65 6.5 8.25 17.3 22.90 —9.24 18.5 10.0 28.5 17.0 17.00 8.3 9.15 25.3 26.15 —5.99 17.0 10.0 27.0 17.0 21.00 9.5 7.75 26.5 29.00 —3.14 25.0 6.0 31.5 18.2 18.85 9.8 7.40 28.0 26.25 —5.89 19.5 5.0 24.5 20.7 20.70 9.2 9.20 29.7 29.70 —2.44 23.0 24.95 10.0 7.50 33.0 32.45 + 0.31 26.9 5.0 31.9 18.13 18.88 14.8 13.27 32.93 32.14 17.0 13.0 30.0 21.5 12.0 33.5 584 University of California Publications in Agricultural Sciences [Vol. 1 TABLE IXc MnS0 4 Set — Third Crop — Greenhouse Soil MnS0 4 added to soil in parts per 1,000,000 o •Sis 11 'S s be £ > _ o IS _ .S¥.5 "3 a % O tn ~ ■- - - bo -■° o fc- o a Average weight of dry matter above surface o 'S "o £2 3 to *S boJS >r < o o bo u p a o a s t3 o t. t, Err P, 2 S '3 . 13 ■tu° £X~ , g3 : < o s U — si ® c a r — * £ E fe Zz g|g c 1 500 gm. 11.90 gm. 11.90 gm. 4.70 gm. 4.70 gm. 16.60 gm. 16.60 gm. 1.40 gm. 1.40 gm. 18.00 gm. 18.00 + 0.57 2* 500 3 1000 9.54 10.02 3.96 3.98 13.50 14.00 2.00 2.35 15.50 16.35 —1.08 4 1000 10.50 4.00 14.50 2.70 17.20 5 1500 15.76 13.13 4.24 4.67 20.00 17.80 1.50 1.25 21.50 19.05 + 1.62 6 1500 10.50 5.10 15.60 1.00 16.60 7 2000 21.30 17.20 4.10 3.50 25.40 20.70 1.40 1.50 26.80 22.20 +4.77 8 2000 13.10 2.90 16.00 1.60 17.60 9 10 2500 2500 20.15 15.85 18.00 5.85 3.15 4.50 26.00 19.00 22.50 2.60 2.55 2.58 L'S.lill 21.55 25.08 + 7.65 11 3000 17.80 16.05 5.00 3.85 22.80 19.90 1.40 1.85 24.20 21.75 +4.33 12 3000 14.30 2.70 17.00 2.30 19.30 13 3500 13.70 12.95 4.90 4.35 IS. CO 17.30 1.50 2.05 20.10 19.35 + 1.92 14 3500 12.20 3.80 16.00 2.60 18.60 15 4000 12.25 12.25 4.15 4.15 16.40 16.40 3.50 3.50 19.90 19.90 + 2.47 16 4000 17 4500 12.44 12.40 3.76 3.70 16.20 16.10 2.40 2.40 18.60 18.50 + 1.07 18 4500 12.36 3.64 16.00 2.40 18.40 19 5000 12.40 11.87 3.20 3.83 15.60 15.70 3.20 2.70 18.80 18.40 + 0.97 20 5000 11.35 4.45 15.80 2.20 18.00 21 5500 9.80 9.80 4.40 4.40 14.20 14.20 2.80 2.80 17.00 17.00 —0.43 22 5500 23 6000 9.64 12.52 4.36 3.48 14.00 16.00 2.10 2.30 16.10 18.30 + 0.87 24 6000 15.40 2.60 18.00 2.50 20.60 25 Control 12.25 12.80 3.25 2.73 15.50 15.53 1.40 1.90 16.90 17.43 26 Control 13.30 2.30 15.60 2.30 17.90 27 Control 12.85 2.65 15.50 2.00 17.50 * Contaminated t iy leakj ' roof. 1917] Lipman-Gericke : Smelter Wastes and Barley Growth TABLE X« MnCL, Set — First Crop — Greenhouse Soil "** ft 60 6J3 ^ tn S M Sh £ 'O^o <« & >« £ M 'St: £«t: >« «fto *J & g -S 6D.H £ « w M ° £ -s 5 -tig 6DP h- 6Cg fc, ^ 'Ji.k ^hS Uo! c^§ jSg £<° »g £<*> -g-og Si-Oo oo S « ^ P- w > ^ gm. gm, gm. gm. gm. gm. gm. 1 500 60.0 58.00 60.0 58.00 12.5 2 500 56.0 56.0 11.0 3 1000 68.2 73.60 68.2 73.60 13.5 4 1000 79.0 79.0 10.5 5 1500 57.2 65.60 57.2 65.60 13.5 6 1500 74.0 74.0 11.5 7 2000 37.0 37.55 37.0 37.55 5.9 8 2000 38.1 38.1 8.0 9 2500 32.0 35.60 32.0 35.60 12.5 10 2500 39.2 39.2 11.0 11 3000 26.0 28.10 26.0 28.10 6.0 12 3000 30.2 30.2 7.5 13 2500 25.2 22.10 25.2 22.10 4.0 14 3500 19.0 19.0 2.5 15* 4000 20.0 20.00 20.0 20.00 1.0 16* 4000 17 4500 14.0 14.45 14.0 14.45 1.5 18 4500 14.9 14.0 1.1 19 5000 12.9 12.90 12.9 12.90 1.2 20* 5000 21 5500 4.5 6.70 4.5 6.70 1.0 1.05 5.5 7.75 —44.38 22 5500 8.9 8.9 1.1 10.0 23 6000 5.2 3.55 5.2 3.55 .7 .45 5.9 4.00 —48.13 24 6000 1.9 1.9 .2 2.1 25 Control 41.4 41.46 41.4 41.46 12.5 10.66 53.9 52.13 26 Control 43.0 43.0 11.0 54.0 27 Control 40.0 40.0 8.5 48.5 * Plants died during growing period. £ 61 t. z. *- ^ p CS V -■ a p H-o p. bj) 3 £ C° a; -3 ft 2 -is < c a — OJ c5 > si a 3 jH « £ <*a > -"O o hoe ^ "St! oj g 3 2 b" u u > < O S3 O 3 o £2 %■ a> 60.2 2 ° S2 27.85 6.9 7.95 36.40 35.80 +3.66 8 2000 21.16 5.04 26.20 9.0 35.20 9 2500 22.00 20.15 5.00 6.45 27.00 26.60 8.0 8.50 35.00 35.10 + 2.96 10 2500 18.30 7.90 26.20 9.0 35.20 11 3000 26.05 23.55 3.95 4.30 30.00 27.85 10.0 7.60 40.00 35.45 + 3.31 12 3000 21.04 4.66 25.70 5.2 30.90 13 3500 20.66 22.83 1.34 1.92 22.00 24.75 9.0 7.75 31.00 32.50 + 0.36 14 3500 25.00 2.50 27.50 6.5 34.00 15 4000 32.07 33.04 .93 1.46 33.00 34.50 6.4 6.20 39.40 40.70 +8.56 16 4000 34.00 2.00 36.00 6.0 42.00 17 4500 30.40 27.80 30.40 27.80 6.0 5.70 36.40 33.50 + 1.36 18 4500 25.20 25.20 5.4 30.60 19 5000 29.60 26.05 .90 .90 30.50 26.50 6.5 5.25 37.00 31.75 —0.39 20 5000 22.50 22.50 4.0 26.50 21 5500 27.03 28.70 .47 .47 27.50 29.00 6.0 5.50 33.50 34.50 +2.36 22 5500 30.50 30.50 5.0 35.50 23 6000 24.05 27.04 .45 .46 24.50 27.75 6.0 5.50 30.50 33.25 + 1.11 24 6000 30.03 .47 31.00 5.0 36.00 25 26 Control Control 13.08 12.87 13.71 5.05 4.13 5.16 18.13 17.00 18.88 14.8 13.0 13.20 ;-:2.!»:: 30.00 32.14 27 Control 15.17 6.31 21.50 12.0 33.50 19171 Lipman-Gericlce: Smelter Wastes and Barley Growth 587 TABLE Xc MnCl 2 Set — Third Crop — Greenhouse Soil. MnCl 2 added to soil in parts pel 1,000,000 O lis 1 S S < O O 2 _ > <* p- be .a '3 8>.S « bfi t> ™ . q> t-i J-< > !"- < O eS O £g bti g M.J2 O 111 — a ~ o u t. H"e p. rl & "H, " bC _3 "S . 13 «-3 p, M— . « n s fell 12 lis £sSe 1 500 gm. 12.68 gm. 12.97 gm. 2.76 gm. 4.52 gm. 17.20 gm. 18.40 gm. 1.40 gm. 1.63 gm. 18.60 gm. 20.03 + 2.60 2 500 13.25 6.35 19.60 1.85 21.45 3 1000 16.46 15.23 5.74 5.12 22.20 20.35 1.75 1.83 23.95 22.18 + 4.75 4 1000 14.00 4.50 18.50 1.90 20.40 5 1500 12.36 12.40 6.06 4.61 18.40 17.00 2.30 2.05 20.70 19.05 + 1.62 6 1500 12.45 3.15 15.60 1.80 17.40 7 2000 17.60 17.93 6.00 4.87 23.60 22.80 2.20 2.70 25.80 25.50 + 8.07 8 2000 18.25 3.75 22.00 3.20 25.20 9 2500 14.02 13.89 6.28 5.56 20.30 19.45 2.70 2.55 23.00 22.00 + 4.57 10 2500 13.76 4.84 18.60 2.40 21.00 11 3000 21.30 16.90 3.70 3.40 25.00 20.30 2.00 2.60 27.00 22.90 + 5.47 12 3000 12.50 3.10 15.60 3.20 18.80 13 3500 14.64 18.12 5.16 5.18 19.80 23.30 2.30 2.95 22.10 26.25 + 8.82 14 3500 21.60 5.20 26.80 3.60 30.40 15 4000 17.00 18.60 4.00 5.10 21.00 23.70 1.00 1.90 22.00 25.60 + 8.17 16 4000 20.20 6.20 26.40 2.80 29.20 17 4500 23.00 20.30 3.80 4.10 26.80 24.40 1.20 1.20 28.00 25.60 + 8.17 18 4500 17.60 4.40 22.00 1.20 23.20 19 5000 27.70 24.65 3.90 4.15 31.60 28.80 1.80 1.90 33.40 30.70 + 13.27 20 5000 21.60 4.40 26.00 2.00 28.00 21 5500 17.36 16.03 5.24 2.97 22.60 19.00 .70 22.60 19.35 + 1.92 22* 5500 14.70 .70 15.40 .70 16.10 23 6000 26.50 20.60 8.90 6.28 35.40 27.70 .40 .35 35.80 28.05 + 10.62 24 6000 16.35 3.65 20.00 .30 20.30 25 Control 12.25 12.80 3.25 2.73 15.50 15.53 1.40 1.90 16.90 17.43 26 Control 13.30 2.30 15.60 2.30 17.90 27 Control 12.85 2.65 15.50 2.00 17.50 * Contaminated by leaky roof.