UNIVERSITY OF CALIFORNIA PUBLICATIONS IN AGRICULTURAL SCIENCE Vol. 3, No. 12, pp. 369-498, 33 text-figs., pis. 43-74 June 30, 1919 ARE SOILS MAPPED UNDER A GIVEN TYPE NAME BY THE BUREAU OF SOILS METHOD CLOSELY SIMILAR TO ONE ANOTHER? BY ROBERT LAKIMORE PENDLETON CONTENTS PAGE Foreword 369 Introduction 370 Need of a classification of soils 371 Historical development of the classification of soils 371 Plan of the present study 376 Discussion of results '. 377 Mechanical analysis 380 Chemical data 395 Bacteriological data 414 Greenhouse data 432 General discussion 467 Summary 481 Appendices 483 A. Methods and technique 483 B. Soil sample locations 490 FOREWORD It is due the author, as well as to the undersigned, that a few words be said by way of preparing the reader for what follows in this paper. It will be observed, first, that the manuscript was, for an unusually long time, in the printer's hands. Those who appreciate, as few do today, the great rapidity with which the theories and the methods in soil and plant study change, will readily catch the signifi- cance of the foregoing sentence. Much of the work done by Mr. Pendleton and some of the methods used may now properly be con- sidered obsolete, or, conservatively speaking, at least obsolescent. Nevertheless, I deem it of some importance to give the results obtained in more or less detail, because of their historical value, and because Mr. 370 University of California Publications in Agricultural Sciences [Vol. 3 Pendleton's residence in India since the paper was written by him has rendered satisfactory changes and deletions practically impossible. Under these circumstances, with the burden of preparing the paper for the press and the reading of the proof falling to me, the author cannot well be held responsible for the inaccuracies and the infelicities of expression which have been carried over from the original manu- script without change. Moreover, the investigation was carried out under my direction, and the plan of attack on the problem, together with the methods employed, were suggested by me. Much that, in the light of present knowledge, is superfluous or patently inexact or erroneous in the paper is due to points of view held by me in 1915, but now happily discarded. For all these, I assume the entire responsibility, and absolve Mr. Pendleton in that regard. On the other hand, the work having been carried out at my sugges- tion and under my direction, I feel constrained, in justice to myself, to say that the views expressed in this paper, and the conclusions drawn are wholly Mr. Pendleton's and are not in agreement with those held by me. I fail to see the cogency of the arguments set forth for soil classification and mapping at this juncture in soil studies, and cannot admit the pertinence of the analogy between classification of other objects and of soils which the author of this paper employs. My own general conclusion from the results obtained by Mr. Pendle- ton is that they cast grave doubt on the validity of the Bureau of Soils method of soil classification and mapping, and, incidentally on all methods devised for that purpose to date. I cannot see how such methods can serve us in scientific work at all, and, from the practical standpoint, it would surely seem that guides for the purchaser of land could be arranged more cheaply and less elaborately than by the soil mapping methods extant. This statement has particular reference to the subdivision of types very minutely, such as, for example, sandy silty clay, clay loam adobe, etc. Such minute classification and sub- division in view of the present state of our knowledge of soils, is analogous, in my opinion, to carrying figures out to four decimal places when it is known that the accuracy of the method makes it impossible for them to be correct beyond the first decimal place. In support of this seemingly radical conclusion, the reader will find much of interest in the recent studies of this laboratory on variability in soils, which have already appeared in this same series. Chas. B. Lipman. INTRODUCTION For several years the University of California has been cooperating with the United States Bureau of Soils in the mapping of the soils of the agricultural portions of the State of California. The system of mapping used is that developed by the Bureau of Soils. During the year 1914-1915 the writer, representing the University of California, was engaged in some of this soil survey work. In that year, in the field, many questions arose regarding the criteria used, the methods. 1919] Pendleton: A Study of Soil Types 371 and the results of the scheme of mapping. It was thought that pos- sibly some of the many questions could be answered through a labora- tory study of some typical soils. This paper is a description of cer- tain parts of the Avork done in this connection. THE NEED OP A CLASSIFICATION OF SOILS Since soils consist of a number of more or less distinct groups they are fitting subjects for classification. In fact, it is my belief that it is as necessary to have a classification for soils as for any other group of natural objects in order that "the various and complex relations may be shown as far as practicable," 1 and that there be a definite basis for systematic and thorough investigations. 2 The advantages of a classification of soils are apparent. But because soils grade gradu- ally into one another, rather than exist as discrete individuals which can be more easily considered and treated from a systematic stand- point, the problem of evolving a satisfactory classification has been particularly difficult. The many and diverse classifications proposed, and the difficulty of applying many of these classifications under con- ditions other than those for which they were evolved, testify to the difficulty of the task in question. The mapping of soils without a classification is impossible, and so a brief summary of the development of soil mapping will bear a close relation to the development of soil classification. HISTORICAL DEVELOPMENT OF THE CLASSIFICATION OF SOILS The early history of the making of soil maps is that of geologic maps as well, when soils, from the agricultural standpoint, and the less distinct geological formations as such, were not sharply distin- guished. Blanck 3 has an excellent treatment of the development of soil mapping and of the modern continental European conceptions of the nature and significance of soil maps. According to Blanck the earliest record of a proposal to make a map to show something of the nature of the actual material composing the surface of the earth is that of Lister's proposal, in 1683, to the Royal Society of London. i Coffey, G. N., Proc. Amer. Soc. Agron., vol. 1 (1909), p. 175. 2 Cameron, F. K., Eighth Internat. Cong. Chem., vol. 26 (1912), sees, via-xib; app. pp. 699-706. sFuhling, Landw. Ztg., vol. 60 (1911), pp. 121-45. 372 University of Calif ornia Publications in Agricultural Sciences [Vol. 3 But it was not until 1743 that Packe executed a map of Kent, showing the occurrence of minerals by symbols. Apparently the next advance was by the Germans, when Fuchsel, 1773, and Gloser, 1775, first used colors to show granite, limestone, etc. This work constituted the first real geologic map in the modern sense. There was not much activity in this line of geologic work until 1870 or later. Such activity as there was showed a lack of emphasis on soils in the agricultural sense of the term. The work on the geologic drifts of northern Europe, and studies of the more recent lowland formations and soils of Germany led to soil mapping. The first real soil map, according to Blanck, was prepared by Benningsten-Forder of Halle, in 1864-67 ; while Carnot 4 states that in 1863 M. Scipion Gras used superposable maps of the Depart- ment of Isere, showing (1) geology, (2) agricultural soils, (3) alti- tudes of agricultural regions, and (4) culture. The first true geologic- agronomic map published by the Preussischegeologische Landesan- stalt appeared in 1878. The school of soil classification and mapping just mentioned, using the geologic maps and methods as a point of departure have evolved numerous though similar systems of recording the agrogeologic data on the map. The geologic formation is shown by the color, and the soil textures by sjmibols, while one or more of the following groups of data appear and may be shown : topography by contours, subter- ranean water by blue figures, location of borings in red with figures referring to tables, amount of plant food elements or substances by figures or hatchings, varying directions, color, or nature of lines, etc. The nature and amount of the data shown and the manner of repre- senting them vary a great deal. Some soilists, to use a term proposed by Coffey, 5 advocate and use superposable maps to show one or more groups of data, thus avoiding unnecessary confusion on the main map. Hazard proposed a scheme of classification which is quite as directly connected with the economic factors controlling the crops grown, and with the assessable valuation of the land, as with the actual or potential fertility of the soil itself. There are several classi- fications of this type, involving the assessable values of the land. i Rapport BUT Les cartes agronomiques, Bull. Min. Agr. France, 1893, no. 8, pp. 956 73. • r > Jour. Amor. Soc. Agron., vol. 8 (1916), p. 239. eLandw. Jahrb., vol. 29 (1900), pp. 805-911. Gregoire, A., and Halet, F., Bull. Inst. Chem. et Bact. Gembloux, 1906, no. 75, pp. 1-43. 1919] Pendleton : A Study of Soil Types 373 This development of the mapping of soils as an outgrowth of areal geology in France and Germany may be contrasted with the develop- ment of soil classification from other viewpoints, such as that of the Russian school. In Russia there is not the predominance of residual and shallow soils which characterize much of western Europe and which in France especially have led to the adoption of the geologic basis of classification. Dokoutchayev and Sibirtzev have been the chief proponents of a classification of soils based upon the ' ' conception of a soil as a natural body having a definite genesis and a distinct nature of its own. ' ' r The genetic conditions of the formation of natural soils include the following variable factors which cause variation : (1) The petrographic type of the parent rock; (2) the nature and intensity of the processes of disintegration, in connection with the local climatic and topo- graphic conditions; (3) the quantity and quality of that complexity of organisms which participate in the formation of the soil and incorporate their remains in it ; (-4) the nature of the changes to which these remains are subjected in the soil, under the local climatic conditions and physico-chemical properties of the soil medium; (5) the mechanical displacement of the particles of the soil, provided this displacement does not destroy the fundamental properties of the soil, its geo- biological character, and does not remove the soil from the parent rock; and (6) the duration of the processes of soil formation. Upon this genetic basis there has been developed a series of soil zones, ranging from the laterite soils in the tropics to the tundras in the Arctic regions. The outstanding and controlling factor in the scheme proposed is the relation of these zones to climate. For this reason the statement usually seen is that climate is the basis of the classification. 8 There are nearly as many groups of intra-zonal and azonal soils as of those belonging to the zones proper. The former include alkali, marshy, alluvial, and other soils. Hilgard, while actively interested in the' genetic viewpoint of soil classification, was the foremost proponent of a classification upon the basis of the natural vegetation growing upon the soil. 9 This criterion is not always available, though some groups of plants, as the alkali tolerant ones, are almost invariably present where the condi- . 115. 28 Jbid., pp. 114-15. 1919] Pendleton: A Study of Soil Types 377 same or similar when examined from the laboratory standpoint. For example, we may take the Hanford fine sandy loam, which is one of the types that has been used in the present study. According to the criteria of color, mode of formation, origin (as judged by the presence of mica), nature of subsoil, texture, etc., this soil has been found and mapped in a number of areas that have been mapped in this state. But will these various bodies of soil, from widely separated portions of the state, when judged by laboratory and greenhouse studies on samples as nearly representative as possible, appear to be the same or similar ? The types selected for such a study as this should fulfil the follow- ing conditions : first, they should have at least a reasonably wide dis- tribution in the state so as to have been mapped in a number of differ- ent soil survey areas ; and second, the several types should be repre- sentative of different classes of soils (clays, loams, sandy loams, etc.), so that contrasts could be obtained between the types. In the collection of samples it was aimed to obtain representative samples from each of a number of bodies of soil of the types selected ; not to obtain possible variations from the ideal in any one body. In the laboratory the soils were compared with regard to their physical composition in the surface horizon, to their chemical composition in three horizons, and to their relative bacteriological activities. In the greenhouse the soils (surface horizon only) were placed in large pots and their comparative ability to produce various crops was studied. No claim is made that these criteria should be the ones used in determining the systematic classification of soils or in determining the relative fertility of the soils. They were merely used to determine how nearly the soils classed under a given type name agree from the standpoints named. DISCUSSION OF RESULTS The bacteriological and chemical determinations were run in dupli- cate so that the figures presented are averages. It is considered that this gives fairer figures for comparison, especially since the determina- tions were run on separate samples, and not on aliquots of a single solution from a single sample. There is a very important factor which should always be kept in mind especially when considering the bacteriological and greenhouse comparisons. This is the factor of the probable error. Though the 378 University of California "Publications in Agricultural Sciences [Vol. 3 advisability of judging all results in the light of the probable error is admitted, no attempt has been made to apply this factor to the results reported in this paper. As the result of the effect which such a factor might have upon the results of bacteriological determina- tions carried on only in duplicate, or upon the results of greenhouse work done in triplicate, one hesitates to draw conclusions, especially those based upon minor variations. Hence in this work only the more marked results will be considered of significance. When planning the work it was thought that three or four samples of a type would be enough to show whether or not a given type was approximately uniform, or widely variable, and as to whether the types were similar to one another, or quite dissimilar. But it now seems, after comparing the determinations run on the larger number of samples of the Hanford and San Joaquin types, 9 and 8 respec- tively, with the determinations run on the Altamont and Diablo types, of which there were a much smaller number of samples, 3 and 4 respectively, that the larger series gives a much better insight into the variations of a given type and affords a much better basis for con- clusions. Hence, as regards the laboratory work thus far carried out, the emphasis has been placed upon the Hanford fine sandy loam and the San Joaquin sandy loam. Determinations have not been completed on the Altamont and Diablo series to the extent that they have on the former two. It is of no little significance that the Hanford fine sandy loam and the San Joaquin sandy loam are very widely contrasted soils agricul- turally. The Hanford is typical of good recent alluvial soil in this state ; while the San Joaquin is typical of wide expanses of ' ' old valley filling" soils that are considered poor as regards crop producing power and are underlain by compact iron-cemented hardpan. Conse- quently, the results of comparing soils so different from an agricul- tural point of view, and so radically different as regards soil survey criteria (though the textures are quite similar) will be of considerable interest. They are of greater interest than the comparisons between the Diablo and Altamont soils, as the latter are quite similar in agri- cultural value and use, as well as in field appearances. Between the Diablo or Altamont and the Hanford or San Joaquin one cannot judge as closely regarding variations, for the soils are so radically different. On the other hand, one can compare the soils of the heavy and light types to see to what extent the chemical and bacteriological results differ as compared with the physical results. 02.5 0.5 /. Z. 4 9. 16. 32. 64. Grits. Size of Particles nam - Fig. 1. Graph showing the results of the Hilgard elutriator method of mechanical analysis on the four samples of Diablo clay adobe. 380 University of California Publications in Agricultural Sciences [Vol. 3 Mechanical Analysis Hilgarcl Elutriator Method. — That there is a wide variation be- tween the samples is apparent (figs. 1-4). In fact, there is about as wide a range of differences among the samples of the Hanford % 45 40 35 30 20 i:. 10 j A i 1 // // , / \ // \ \ 1 \ 1 v \ i\ \ \ \ \ \ \ \ \ \\ / \ \ / / / / v. *'ic moisture , % 0.98 2.48 1.38 1.22 0.75 0.70 0.75 1.57 Note. — All weighings made on the water free basis. 390 University of California Publications in Agricultural Sciences [Vol. 3 Table 5 — Mechanical Analyses, Hilgard Elutriator Method Han ford Fine Sandy Loam Separates Name Clay Fine silt Medium silt Coarse silt Fine sand Medium sand Coarse sand Velocity, mm. Diameter per mm. second 0.25 0.25 0.5 1 2 4 8 16 32 64 .01 .01 -.016 .016-.025 .025-.036 .036-.047 .047-.072 .072-12 .12 -.16 .16- .30 .30- .50 Total weight of separates, gm. Weight of original sample, gm. Grits, % 0.5-2.0 Hygroscopic moisture, % 14- A % 12.89 37.25 4.19 8.63 7.95 6.23 5.26 7.15 8.81 1.43 20.19 19.46 4.12' 2.73 Samples 15-A % 8.16 19.39 3.05 5.04 6.57 10.23 12.31 13.93 15.29 6.02' 20.23 19.90 13.23 0.49 16-A % 11.97 24.61 3.22 5.06 5.99 7.27 8.57 9.76 16.05 7.51 20.53 19.69 25.47 1.54 19-A % 11.09 5.95 1.67 5.27 7.14 12.76 17.79 12.00 24.20 2.13 20.08 19.82 7.85 0.89 20-A % 10.55 22.09 6.40 8.40 7.68 9.93 10.48 12.29 10.03 2.70 20.27 19.73 6.71 1.34 22-A 23-A 7.97 14.15 3.15 5.29 6.47 11.30 17.15 17.39 14.87 2.27 20.06 19.81 3.07 0.94 8.68 22.57 5.90 6.89 10.53 13.03 12.71 7.94 9.88 1.85 20.30 19.78 7.24 1.10 2 4- A % 6.47 11.11 1.20 5.08 7.48 13.91 19.27 21.56 12.36 1.50 20.26 19.83 6.85 0.84 25-A % 6.65 14.54 1.59 6.36 7.91 12.64 18.11 9.55 19.15 3.50 19.18 19.78 3.83 1.10 Table 6 — Mechanical Analyses, Bureau of Soils Method Diablo Clay Adobe Separates Sampb 3S Name Diameter mm. l-A 2-A % 5-A % 6-A % Clay .005 44.81 44.44 45.67 56.01 Silt .005- .05 32.00 42.51 23.01 14.28 Very fine sand .05 - .10 19.61 11.35 21.58 25.58 Fine sand .10 - .25 1.36 1.33 4.81 2.10 Medium sand .25 - .5 0.26 0.69 0.95 2.05 Coarse sand .5 -1.0 0.58 0.20 1.56 0.00 Fine gravel 1.0 -2.0 0.03 0.02 0.04 0.00 Note. — Determinations made by the Division of Soil Technology. Table 7 — Mechanical Analyses, Bureau of Soils Method Altamont Clay Loam Separates Samples Name Diameter mm. 3-A % 4-A % 7-A % Clav .005 33.19 26.50 31.84 Silt .005- .05 31.76 17.35 37.40 Very fine sand .05 - .10 22.81 39.15 24.70 Fine sand .10 - .25 8.97 6.08 3.27 Medium sand .25 - .5 1.99 7.78 0.92 Coarse sand .5 -1.0 " 1.74 3.06 0.55 Fine gravel 1.0 -2.0 1.01 1.22 0.22 NOTE. — Determinations made by the Division of Soil Technology. 1919] Pendleton: A Study of Soil Types 391 Table 8 — Mechanical Analyses, Bureau of Soils Method San Joaquin Sandy Loam Separal es Samples A Name ^ Diameter mm. 10-A % ll-A % 12-A % 13-A % 17-A % 18-A % 21-A % 2 6- A % Clay .005 10.78 15.77 16.16 16.94 11.77 10.49 8.28 17.38 Silt .005- .05 21.60 35.97 25.04 22.70 15.97 2'6.74 17.70 18.17 Very fine sand .05 - .10 28.07 18.53 27.42 47.01 20.42 12.02' 15.92 13.84 Fine sand .10 - .25 19.96 2.66 17.07 3.99 22.57 16.61 21.27 10.26 Medium sand .25 - .5 9.20 6.96 5.80 4.69 10.75 13.85 13.57 14.72 Coarse sand .5 -1.0 9.08 8.51 6.52 2.96 13.81 16.52 21.41 24.26 Fine gravel 1.0 -2.0 1.34 12.52' 2.15 1.81 3.13 4.07 2.07 2.02 Note. — Determinations made by the Di vision of Soil Technology. Table 9 — Mechanical Analyses, Bureau of Soils Method Ranford Fine Sandy Loam Separates A Samples A f *\ Diameter Name mm. 14-A % 15-A % 16- A % 19- A % 20-A % 22-A % 23-A % 2 4- A % 25-A % Clay .005 14.10 12.08 16.84 15.28 15.95 7.79 10.61 9.83 7.60 Silt .005- .05 39.25 22.42 16.16 15.03 32.90 22.70 24.38 11.42 12.90 Very fine sand .05 - .10 22.66 37.12 16.46 32.87 22.58 36.15 38.73 42.05 67.37 Fine sand .10 - .25 17.54 6.51 17.32 8.13 18.20 27.78 16.51 28.73 5.88 Medium sand .25 - .5 4.71 11.40 11.70 15.42 4.97 4.21 4.66 4.27 3.47 Coarse sand .5 -1.0 1.99 8.49 15.54 9.27 3.07 1.47 3.28 3.01 1.27- Fine gravel 1.0 -2.0 0.13 1.91 5.27 3.63 0.20 0.20 1.48 1.02 1.02 Note. — Determinations made by the Division i af Soil Technology. Moisture Equivalent. — The moisture equivalents of the surface horizon samples were determined by the Division of Soil Technology (table 10, and figs. 9, 10). The different types gave quite distinct averages, though there was considerable variation within the type. The Diablo clay adobe varied from 37% to 57%, with an average of 47%. The Altamont clay loam varied from 22% to 37%, with 28% as an average. The San Joaquin sandy loam varied from 7% to 15%, with the average of 11%. The Hanford fine sandy loam varied from 11% to 25%, with 15% as the average. These figures show that as a whole the moisture equivalents of the several types are distinct, though there is the usual overlapping in some cases. The samples of a given type are in many instances closely similar, though not always or even usually so. 392 University of California Publications in Agricultural Sciences [Vol. 3 60 55 50 45 10 30 25 20 15 10 1 / 1 \ \ \ \ \ \ / / / / Moisture Equivalent Hygro. Coef. 35 ;;<> 20 10 \ \ \ \ \ \ \ \ \ \ \ \ ^- Moisture Equivalent Hygro. Coef. 12 5 6 Soils 3 4 7 Soils Fig. 9. Graph showing the results of the determination of the moisture equivalent and of the hygroscopic coefficient on the four samples of Diablo clay adobe and the three samples of Altamont clay loam. 1919] Pendleton: A Study of Soil Types 393 Table 10 — Moisture Equivalent Diablo Clay A Adobe Altamont Clay Loam San No. Joaquin Loam A Sandy Hanford Fine Loam A Sandy r No. % Average No. % Average % % Average % No. % Average 1-A 49.70 3-A 38.10 10-A 10.30 14-A 25.80 48.90 49.30 37.80 37.95 10.10 10.20 25.20 25.50 2-A 37.40 4-A 23.41 11-A 15.52 15-A 11.50 36.80 37.10 22.35 22.88 15.54 15.53 11.20 11.35 5-A 46.55 ■ 7-A 23.90 12-A 13,72 16-A 15.60 48.10 47.32 23.90 23.90 13.62 13.67 15.60 15.60 6-A 58.80 Average 28.94 13-A 14.50 19-A 13.30 56.80 57.80 14.60 14.55 14.30 13.80 Average i 47.88 17-A 8.90 20- A 18.41 8.98 8.94 18.38 18.39 18-A 2 1-A 26-A 7.92 7.87 7.16 7.09 11.30 11.81 7.89 7.12 11.55 22-A 2 3-A 24-A 12.73 12.22 11.08 10.90 16.30 16.17 12.47 10.99 16.23 Average ! 11.18 25-A 11.17 12.72 11.94 Average 15.14 Note. — Determinations made by the Division of Soil Technology. Table 11 — Hygroscopic Coefficient Diablo Clay A Adobe Altamont Clav A Loam San Joaquin Loam A Sandy Hanford Fine Loam A Sandy No. % Average % No. Average % % No. % Average % No. % Average % 1-A 15.88 3-A 17.48 14-A 5.35 10-A 2.46 15.08 15.48 18.45 17.93 4.70 5.03 2.51 2.49 2-A 9.90 4-A 9,60 15-A 1.31 11-A 3.44 9.48 9.69 7.00 8.30 1.39 1.35 3.45 3.44 5-A 14.18 7-A 7.92 16-A 3.90 12-A 3.58 13.90 14.04 5.92 6.92 3.60 3.75 3.45 3.52 6-A 15.20 Average 11.05 19-A 1.66 13-A 2.50 15.70 15.45 1.80 1.73 2.60 2.55 Average s 13.66 20- A 2.90 17-A 1.84 3.02 2.96 1.62 1.73 22-A 2.48 2.89 2.69 18-A 2.10 2.00 2.05 23-A 2.38 2.53 2.46 21-A 1.98 1.92 1.95 24-A 2.39 26-A 3.57 24-A 2.39 3.52 3.55 2.37 2.38 Average 2.66 25-A 1.78 1.84 1.81 Note. — Determinations made by the Division of Soil Technology. 394 University of California Publications in Agricultural Sciences [Vol. 3 15 10 Moisture Equiv. Hygro. Coef. 10 11 12 13 18 21 2G Soils 20 ir> 10 X \ ^ \ -"" Moisture Equiv. 10 20 22 23 24 Hygro. Coef. 23 Soils Fig. 10. Graph showing the results of the determination of the moisture equivalent and of the hygroscopic coefficient on the eight samples of San Joaquin sandy loam and the nine samples of Ilanford fine sandy loam. Hygroscopic Coefficient. — The determination of this coefficient, also by the Division of Soil Technology, shows no very distinct values for the several types under consideration (table 11, figs. 9,10). The Diablo clay adobe samples vary from 9.6% to 15.4%, with the average of 13.69? • The Altamont clay loam samples vary from 6.9% to 17.9%, averaging 11%. The San Joaquin sandy loam varies from 1919] Pendleton: A Study of Soil Types 39; 1.7% to 3.5%, with the average of 2.66%, while the Hanford fine sandy loam varies from 1.3% to 5%, with the average of 2.68%. There is no question that here the range of values within every type is greater than that from type to type. Even excluding those sam- ples shown by the mechanical analysis to be not true to name there is a wide range within each type — a range too wide to allow one to answer the question of this paper in the affirmative. % V.6 0.2 0.1 00 P 2 5 N 6 Soils Fig. 11. Graph showing the percentages of nitrogen and of phosphorus in the four samples of Diablo clay adobe. The Chemical Data Total Nitrogen Diablo clay adobe. — There is more variation in nitrogen content between the different representatives of the type than one would expect from a visual examination of the soils (table 12 and fig. 11). No. 2 would be expected to contain less nitrogen than no. 5 because of the lighter color, but such is not the case. In the A horizon, no. 5 shows the lowest notal nitrogen content with 0.084%, no. 2 is higher with 0.092%, no. 1 with 0.104%, and no. 6 is the highest with 0.117%. The decrease in the nitrogen content with the increase in depth is normal. In the C horizon, no. 1 has the lowest total nitrogen content with 0.057%, and no. 6 the highest, with 0.078 %. Altamont clay loam. — The agreement between the A samples is fairly close (table 13, and fig. 12). No. 4 has 0.103%, no. 7, 0.104%, and no. 3 has 0.123%. This gives an average for the surface soil of 0.110%, as compared with 0.099% in the Diablo clay adobe. It is to be noted that the nitrogen content of the subsoil is relatively less than that in the Diablo subsoils, 0.071% and 0.056% in the Altamont B and C horizons, respectively, as against 0.076% and 0.065% in the 396 University of California Publications in Agricultural Sciences [Vol. 3 B and C horizons of the Diablo. The average amount of nitrogen is higher in the A horizon of the Altamont than in the Diablo, contrary to what one would expect from the color of the soils, since the Alta- mont is typically a brown soil and the Diablo a dark gray to black soil. San Joaquin sandy loam. — The nitrogen content of these soils is uniformly low (table 14 and fig. 13), from 0.03% to 0.05%, and is but a third to a half of what Hilgard believed adequate for crop production. 0.6 0.2 0.1 00 P 2 5 7 Soils Fig. 12. Graph showing the percentages of nitrogen and of phosphorus in the three samples of Altamont clay loam. ^ P 2 Q 5 0.0 26 Soils Fig. 13. Graph showing the percentages of nitrogen and of phosphorus in the eight samples of San Joaquin sandy loam. The nitrogen content is seen to vary more or less directly with the amount of the finer sediments present in the soil — nos. 11 and 12 being heavy members of the type, with 0.05% and 0.047% respec- tively, and nos. 17 and 18 light members of the type with 0.029% and 0.027% respectively. It may be noted that the nitrogen content of the various horizons are not as far apart as in the other types. The averages for the three horizons are: A — 0.037%, B — 0.027%, and C — 0.026%. It must be borne in mind that the San Joaquin sandy Loam horizons are not full 12-inch samples, and that the total depth of the sampling is less. 1919] Pendleton: A Study of Soil Types 397 Han ford fine sandy loam. — Here again in the A horizon the nitro- gen content is fairly uniform (table 15, and fig. 14), with from 0.045% to 0.072%, if the extra typical no. 14, with 0.119%, be left out of consideration. One would suppose these soils to be higher in their or 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 x / \ — — -~ — -^.^ P205 16 19 20 22 23 24 25 Soils Fig. 14. Graph showing the percentages of nitrogen and of phosphorus in the nine samples of Hanford fine sandy loam. nitrogen content, as compared with the San Joaquin series, than the results show. The B and C horizons of the Hanford samples contain 0.038% and 0.028% nitrogen, respectively, showing that with the increase of deriih there is a more rapid decrease of nitrogen than in the San Joaquin samples, with the nitrogen content of the C horizon of the Hanford only 0.002% above that of the C horizon of the San 398 University of California Publications in Agricultural Sciences [Vol. 3 Joaquin. The greenhouse pot cultures showed the effect of the much higher nitrogen content in no. 14 in giving better color and growth to the plants and especially to the grains. The increase of the nitrogen in the surface of no. 23, as compared with the B and C horizons, might be ascribed to the fertilizers applied to the orange grove where this sample was collected; yet no. 24 is a truck soil which has been fertilized to a considerable extent with barnyard manure. The nitro- gen content of this type, as judged by the previous standards, is quite inadequate. Compare the nitrogen content of the A horizons of the four types : The Diablo has an average of 0.099%, with a range or from 0.084% to 0.117% ; the Altamont has an average of 0.110%, with a range of from 0.103% to 0.123%; ; the San Joaquin has an average of 0.037%?, with a range of from 0.027% to 0.050% ; and the Hanford has an average of 0.062%, with a range of from 0.045% to 0.119%. Thus the total nitrogen content of the several types is reasonably constant within the type and rather distinct for the types. Table 12- -Total Nitrogen Diablo Clay Adobe Horizon A le A % Average % B Average % % C % Average % 0.109 0.105 0.076 0.069 0.056 0.057 0.101 0.063 0.059 0.100 0.072 0.062 0.084 0.092 0.064 0.068 0.058 0.060 0.085 0.065 No sample 0.084 0.084 0.065 0.065 0.114 0.097 0.075 0.122 0.118 0.107 0.102 0.083 0.079 iver age 0.100 0.076 0.065 Sample 3 A % 0.123 0.124 0.103 0.103 0.106 0.104 Table 13 — Total Nitrogen Altamont Clay Loam Horizon Average Average % 0.123 0.103 0.105 0.110 B % 0.089 0.087 0.054 0.053 0.070 0.077 Average % 0.088 0.053 0.073 0.071 C % 0.069 0.067 0.041 0.041 0.061 0.059 Average % 0.068 0.041 0.041 0.060 0.056 1919] Pendleton: A Study of Soil Types 399 Table 14 — Total Nitrogen San Joaquin Sandy Loam Horizon Sample A % Average % B % Average % C % Average % 10 0.037 0.026 0.022 0.038 0.037 0.029 0.027 0.020 0.021 11 0.051 0.042 0.038 0.051 0.051 0.046 0.044 0.040 0.039 12 0.049 0.032 0.042 0.045 0.047 0.034 0.033 0.040 0.041 13 0.040 0.038 0.033 0.040 0.040 0.043 0.040 0.033 0.033 17 0.028 0.019 No sample 0.030 0.029 0.018 0.018 18 0.028 0.016 0.018 0.028 0.017 0.016 0.021 0.019 21 0.029 0.012 0.014 0.030 0.029 0.012 0.012 0.014 0.014 26 0.041 0.026 0.016 0.041 0.041 0.027 0.026 0.017 0.016 Average 0.038 0.027 0.026 Sample 14 15 16 19 20 22 23 24 25 Average Table 15- —Total Nitrogen Hanford Fine Sandy Loam Horizon A A % Average % B % Average % C % Average % 0.113 0.084 0.060 0.126 0.119 0.081 0.082 0.057 0.058 0.052 0.039 0.028 0.055 0.053 0.043 0.041 0.027 0.028 0.058 0.030 0.020 0.054 0.056 0.030 0.023 0.021 0.046 0.025 0.024 0.023 0.044 0.045 0.025 0.025 0.023 0.023 0.062 0.032 0.024 0.058 0.060 0.034 0.033 0.022 0.023 0.057 0.033 0.025 0.061 0.059 0.036 0.034 0.023 0.024 0.075 0.028 0.020 0.071 0.073 0.030 0.029 0.016 0.018 0.050 0.032 0.034 0.028 0.028 0.045 0.031 0.022 0.047 0.046 0.032 0.031 0.024 0.023 0.062 0.038 0.027 400 University of California Publications in Agricultural Sciences [Vol. 3 Humus Diablo clay adobe. — The variations in the humus content of the A samples (table 16, and fig. 15) are moderate, 1.1% to 1.4%, while the B and C horizons do not agree so closely with each other or with the Loss on Ignition / / / / / / / / / / / / / / _. / / —• — :: -~" N>.. <■ -*K, / /. X. X X \ . — 2 .-__ MgO K 2 Humus ■ CaO Soils Fig. 15. Graph showing the loss on ignition, the amount of humus, and the percentages of calcium, magnesium, and potassium in the four samples of Diablo clay adobe. surface foot. The average content of humus in the A samples is 1.26%, in the B samples 0.95%, and in the C samples 0.75%. It is worthy of note that soil no. 2, with the lightest color of the four, and what might be supposed to be a lower humus content, has next to the highest amount. 1919] Pendleton: A Study of Soil Types 401 Altamont clay loam. — Here the variations in the humus content (table 17, and fig. 16) are small in the A horizon, 1.1% to 1.3%. The average is 1.24%. The B and C samples show a good parallelism among themselves, but not so good when compared with the surface. The average of the B horizon is 0.84%, and of the C horizon 0.57%. \ \ V y / / / / ^L- / Loss on Ignition K 2 Humus CaO MgO 3 4 7 Soils Fig. 16. Graph showing the loss on ignition, the amount of humus, and the percentages of calcium, magnesium, and potassium in the three samples of Alta- mont clay loam. San Joaquin sandy loam. — This type contains a considerable quan- tity of humus (table 18, and fig. 17) when one takes into considera- tion the popular criteria for the presence of humus, for the red to reddish brown San Joaquin soils are very different from the brown Altamont or the black Diablo soils. The samples of this type gave 40: University of California Publications in Agricultural Sciences [Vol.3 light colored or nearly colorless humus solutions. But when the ali- quots were ignited, after evaporation, there was a very noticeable blackening and charring of the residue, together with a considerable / \ / \ / \ / / \ / \ / / J / i \\ / / / "v\ / / / / v / \ / / / \\ Y / / s / / V A / \ / \ / / x V-— .. / / / \ ^^**». \ / \ \/ \ \ / \ \ / t- : " ** .... ^ \ ""■:./ *«« ... *"^»l ****■••—.. \, y •• < y "-N... ^ Loss on Ignition K2O Humus MgO CaO 10 12 L3 17 IS 21 26 Soils Fig. 17. Graph showing the loss on ignition, the amount of humus, and the percentages of calcium, magnesium, and potassium in the nine samples of San Joaquin sandy loam. loss in weight. This phenomenon, in the light of the work of Gortner, 27 shows that these soils have a "humus" content above that which they might be supposed to have, because of the almost complete absence of 27 soil Science, vol. 2 (1916), pp. 395-442. 1919] Pendleton: A Study of Soil Types 403 the "black pigment." Soil no. 26, probably the only virgin soil in the series, shows a particularly high content of humus for such a soil, though from the color of the soil one would suspect but very little humus. The agreement between the three horizons of the San Joaquin sandy loam samples is close. The average content of humus was 0.68% in the A, 0.51% in the B, and 0.38% in the C horizon. Han ford fine sandy loam. — The variations in humus content in this type are greater than in any of the others (table 19, and fig. 18). This is possibly because of two factors : the open texture of the soil, hence the rapid loss of organic matter by oxidation processes ; and secondly, the high agricultural value of this soil, which has led to a greater appli- cation of fertilizers than has been the case with the other soils. The actual variations in the humus content are large, 0.7% to 2.1% with the average of 1.15% for horizon A, from 0.5% to 1.8% with the aver- age of 0.81% for B, and from 0.44% to 1.07% with the average of 0.59% for C. The extra-typical sample no. 14 is above any of the others in the total humus content. The variations in the subsoil humus content are more or less parallel to those of the surface soil. The following averages of the humus content of horizon A, Diablo 1.26%, Altamont 1.24%, San Joaquin 0.68%, Hanford 1.15%, show that there is not much difference between the soils, except for the San Joaquin sandy loam, which has an average of half the others. Within the type the soils may be nearly alike, as in the San Joaquin and Alta- mont, or may be variable to a large degree, as in the Hanford. The variations in the humus content of the soils are small, considering the diverse nature of the soils, and the usual methods for judging the quantity of humus. Table 16 — Humus (and Humus Ash) Diablo Clay Adobe Humus Horizons A Humus ash Horizons A Sample A % Average % B Average C % % Average % A Average % % B % Average % C % Aver- age % 1 1.08 0.51 0.18 0.55 0.75 0.45 1.08 1.08 0.51 0.51 0.24 0.21 0.56 0.56 0.73 0.74 0.46 0.46 2 1.40 1.16 1.09 1.01 0.96 1.09 1.38 1.39 1.15 1.15 1.02 1.06 1.03 1.02 0.96 0.96 0.96 1.03 5 1.17 0.87 1.08 1.19 1.12 1.15 0.91 0.89 1.10 1.09 1.14 1.17 6 1.48 1.26 0.95 0.98 0.88 0.78 Werag 1.37 3 1.43 1.26 1.26 1.26 0.95 0.99 0.97 0.72 0.95 0.96 0.91 0.91 0.90 0.95 0.85 0.81 0.77 404 % University of California Publications in Agricultural Sciences [Vol. 3 Humus 14 15 H> 19 20 22 23 24 25 Soila Pig. 18. Graph showing the loss on ignition, the amount of humus, and the percentages of calcium, magnesium, and potassium in the nine samples of Hanford fine sandy loam. 1919] Pendleton: A Study of Soil Types 405 Table 17 — Humus (and Humus Ash) Altamont Clay Loam Humus Horizons A Average B Average C Average Sample % % % % % % 3 1.06 0.89 0.59 1.13 1.09 0.84 0.86 0.58 0.59 4 1.30 0.69 0.59 1.33 1.31 0.71 0.70 0.28 0.43 7 1.32 0.95 0.68 1.31 1.32 0.96 0.96 0.68 0.68 Average 1.24 0.84 . 0.57 Humus ash Horizons Aver- A Average B Average C age % % % % % % 1.29 1.08 0.95 1.23 1.26 1.28 1.18 0.95 0.95 0.80 0.98 0.91 0.85 0.83 0.98 0.98 1.03 0.97 0.72 0.87 1.09 0.75 0.74 0.88 0.88 1.08 1.08 0.94 1.01 1.00 Table 18 — Humus (and Humus Ash) San Joaquin Sandy Loam Humus Horizons A Humus ash Horizons A Sample A Average % % B Average % % C Average % % A Average % % B Average % % C % Aver- age % 10 0.66 0.66 0.53 0.53 0.27 0.27 1.31 1.31 1.33 1.33 0.67 0.67 11 0.75 0.41 0.37 0.51 0.66 0.58 0.71 0.73 0.41 0.37 0.69 0.60 0.66 0.58 12 0.62 0.49 0.32 0.88 1.50 0.80 0.65 0.64 0.49 0.32 0.95 0.91 1.50 0.80 13 0.75 0.50 0.35 1.38 0.90 1.02 0.78 0.77 0.50 0.35 1.36 1.37 0.90 1.02 17 0.51 0.51 0.51 0.38 0.38 0.53 0.57 0.55 1.23 1.23 18 0.56 0.60 0.42 0.61 0.76 1.79 0.60 0.58 0.58 0.59 0.42 0.56 0.59 0.75 0.76 1.79 21 0.52 0.19 0.18 0.53 0.37 0.37 0.52 0.52 0.21 0.40 0.21 0.19 0.54 0.53 0.37 0.37 0.48 0.42 26 1.04 0.79 0.68 0.89 3.57 5.28 1.01 1.02 0.79 0.79 0.82 0.75 0.76 0.83 3.63 3.60 5.46 5.35 Average 0.66 0.51 0.38 0.83 1.24 1.51 Excluding no. 26 0.95 0.87 Loss on Ignition The loss on ignition of the A horizon varies directly with the tex- ture of the soil, the heavier soils losing more on heating. Obviously the water of combination of the clay is a large factor in this loss. In the San Joaquin sandy loam the loss on ignition was determined in the three horizons. In the other three types the A horizon was the only one examined (tables 20, 21, and figs. 15-18). 406 University of California Publications in Agricultural Sciences [Vol. 3 Table 19 — Humus (and Humu s Ash . Hanford Fin ,e Sandy Loam Humus Horizons Humus ash Horizons Sample A % Average B % % Average C % % Average A Average % % B Average % % C % Aver- age % 14 2.11 1.81 1.10 1.14 1.24 1.01 2.09 2.10 1.78 1.79 1.05 1.07 1.17 1.16 1.27 1.26 1.09 1.05 15 1.79 0.88 1.04 1.88 0.94 0.92 1.77 1.78 0.93 0.90 0.67 0.86 1.85 1.86 0.89 0.92 0.91 0.92 16 1.20 0.73 0.41 0.91 0.93 0.90 1.20 1.20 0.73 0.73 0.46 0.44 0.91 0.91 1.47 0.93 0.90 0.90 19 0.73 0.51 0.45 0.48 0.57 0.78 0.74 0.73 0.50 0.51 0.55 0.50 0.47 0.48 0.58 0.58 0.76 0.77 20 1.08 0.86 0.59 0.52 0.90 0.79 1.06 1.07 0.89 0.88 0.50 0.55 0.56 0.54 0.90 0.90 0.78 0.78 22 0.96 0.73 0.58 0.59 0.60 0.58 0.96 0.96 0.71 0.72 0.56 0.57 0.59 0.59 0.60 0.60 0.63 0.61 23 1.04 0.59 0.38 0.58 0.45 0.39 1.07 1.05 0.62 0.61 0.38 0.38 0.57 0.58 0.41 0.43 0.37 0.38 24 0.73 0.55 0.56 0.58 0.69 0.82 0.73 0.73 0.61 0.58 0.51 0.54 0.56 0.57 0.69 0.69 0.80 0.81 25 0.71 0.58 0.45 0.57 0.67 0.74 0.69 0.70 0.56 0.57 0.42 0.44 0.61 0.59 0.71 0.69 0.78 0.76 Average 1.15 0.82 0.59 0.81 0.78 0.78 Diablo clay adobe. — The variation in these samples was from 5.6% to 8.6%, with the average of 6.8%. The Altamont clay loam has a variation of from 5% to 8.7%, averaging 6.7%. The San Joa- quin sandy loam has a range of variation between 1.6% and 4.2%, with an average of 2.6%. The loss on ignition of the lower horizons increases over that of the surface, because of the increase in texture. The B horizon shows an average loss of 3.9% and the C horizon of 4.67%. The Hanford fine sandy loam range of variation in the loss on ignition is, excluding no. 14, from 2.2% to 3.9%, with an average of 3.4%. Thus the curve for this type is quite uniform, except for no. 14, which shows a loss of 6.9%. It is seen that the averages in the loss on ignition of the A horizons of the Diablo and Altamont soils are close, and high, 6.8% and 6.7% respectively. The averages of the San Joaquin and Hanford sam- ples, 2.6% and 3.4% respectively, are low and not widely separated. Since the values for the types overlap considerably, and the averages are not distinct, except between the light and heavy groups, there is no significant distinction between the four types by this determination. 1919] Pendleton: A Study of Soil Types 407 Table 20 — Loss on Ignition (Surface horizon only) Diab lo Clay Adobe A * % Altamont Clay % Loam % Hanford Fine Loam A Sandy ^ % % 1-A 6.62 3-A 8.74 14-A 6.90 6.66 6.64 8.82 8.78 6.95 6.92 2-A 6.57 4-A 5.05 15-A 2.27 6.64 6.60 5.05 5.05 2.30 2.28 5-A 5.61 7-A 6.58 16-A 3.26 5.61 6.46 6.52 3.24 3.25 6-A 8.67 8.71 8.69 A verage 6.78 19- A 3.10 3.13 3.11 Average 6.88 20-A 3.90 3.94 3.92 2 2-A 3.06 3.07 3.06 23-A 3.48 3.45 3.46 24-A 2.60 2.60 2.60 2 5-A 2.68 2.72 2.70 Average 3.48 Table 21 — Loss on Ignition San Joaquin Sandy Loam Sample A % Average % 10 2.13 2.17 2.15 11 3.23 3.20 3.21 12 5.37 3.22 4.29 13 2.94 2.96 2.95 17 1.85 1.88 1.86 18 1.82 1.83 1.82 21 1.68 1.69 1.68 26 3.30 3.30 Avera ge 2.66 Ho rizon A B % Average % 2.32 2.27 2.29 6.33 6.16 6.24 2.97 3.18 3.07 6.58 6.75 6.66 2.54 2.61 2.57 2.18 2.18 2.18 1.60 1.56 1.58 6.97 6.95 6.96 3.94 c % 3.10 3.08 6.57 6.67 Average 3.09 6.62 5.54 5.54 3.97 6.07 5.02 NO! sample 2.90 2.89 2.89 3.31 3.33 3.32 6.18 6.18 4.67 408 University of California Publications in Agricultural Sciences [Vol. 3 Calcium The Diablo, Altamont, and Hanford soils were analyzed for their calcium in the A horizon only, while the A, B, and C horizons of the San Joaquin sandy loam were analyzed (tables 22, 23, and figs. 15-18). Diablo clay adobe. — There is much divergence in the amounts of CaO in this type, varying from 0.36% to 2.05%, with the average of 1.23%. Altamont clay loam. — In this type there is a little greater varia- tion than in the Diablo samples, with a range of from 0.78% to 5.64%, averaging 2.44% CaO. In both this soil and in the Diablo the wide variation in the lime content is undoubtedly due to the nature of the parent rock, since the soils are residual: San Joaquin sandy loam. — In the CaO content there is no uni- formity among the samples. The A samples of this type contain from 0.47% to 2.98%, with an average of 1.65%. It would seem that the materials from which the soils were derived were of varying composi- tion. For from the present climatic conditions soil no. 25 is the one subject to the least leaching, and yet has the least CaO content. The B and C percentages follow the surface very closely — sufficiently so to necessitate no particular explanation. The range of variation in the B horizon is from 0.11% to 2.42%, and the average is 1.42%. The C samples vary from 0.17% to 2.81%, with the average of 1.52%. Hanford fine sandy loam. — The A samples of this type contain from 2.56% CaO to 4.69%, with 3.33% as the average. The varia- tions are not so marked among the series of this type as in the cases of the other three soils. The absolute range is nearly as great, but the relative variation is less. Even though there are differences between the average CaO con- tent in the several types, the wide variation in the amount found in the several samples of a given type, and the overlapping of these amounts from the different types entirely preclude any statement that as regards the calcium content the soils of any one type are closely similar to one another, or that one type has a higher or lower lime content than another. 1919] Pendleton: A Study of Soil Types 409 Table 22 — Calcium as CaO (Surface horizons only) Bh iblo Clay Adobe A % Altamont Clay A Loam Hanford Fine Loam Sandy r ~ % % % % 1-A 1.86 3-A 5.64 14-A 2.91 1.80 1.83 5.64 2.99 2.95 2-A 2.12 4-A 0.92 15-A 2.98 1.98 2.05 0.88 0.90 3.22 3.10 5-A 0.56 7-A 0.89 16-A 2.48 0.17 0.36 0.67 0.78 2.65 2.56 6-A 0.67 0.67 A verage 2.44 19-A 3.28 3.17 3.22 Average 1.23 20-A 2.69 2.73 2.71 22-A > 3.80 3.92 3.86 23-A 2.88 3.00 2.94 24-A 3.88 4.00 3.94 25- A 4.58 4.80 4.69 Average 3.33 Table 23 — Calcium as CaO San Joaquin Sandy Loam Horizon Sample r A % Average % B Average % C % Average % 10 0.67 0.82 1.11 0.62 0.64 1.03 0.92 1.12 1.11 11 1.94 1.62 1.65 1.26 1.60 1.70 1.66 1.55 1.60 12 3.12 2.21 2.61 3.50 3.31 2.21 3.01 2.81 13 2.83 2.38 2.46 3.13 2.98 2.46 2.42 2.79 2.62 17 1.83 1.92 No sample 2.08 1.95 2.08 2.00 18 1.40 1.00 1.48 1.34 1.37 1.45 1.22 1.42 1.45 21 0.91 0.89 0.85 0.84 0.87 0.83 0.86 0.89 0.87 26 0.48 0.13 0.17 Avei 0.47 age 0.47 1.65 0.10 0.11 1.42 0.17 0.17 1.52 410 University of California Publications in Agricultural Sciences [Vol. 3 Magnesium as MgO Diablo clay adobe. — This type shows a moderate variability in the magnesium content, with from 1.13% MgO to 3.26%, averaging 2.09%. The largest quantity is three times that of the smallest, (tables 24, 25, figs. 15-18). Altamont clay loam. — Within the three samples of this type the range in the MgO content is very great, from 0.07% to 1.90%, with the average of 1.05%. The largest is twenty-seven times that of the smallest. San Joaquin sandy loam. — The total MgO in the samples of the type is low, considering that some soils reported by Hilgard contain from 1% to 3% magnesia by the acid digestion. The variation within the A horizon is from 0.34% to 0.90%, with the average of 0.62%, i.e., the largest is three times the smallest. The quantities in the B horizon are somewhat erratic as compared with those of the surface, yet in both the B and C horizons the results approach those of the surface sufficiently to give a rough parallelism. The greater amount of clay and fine silts with the increase of depth gives, as one would expect, an increase of magnesium. The average MgO content in the B horizon is 0.81%, and in the C horizon 1.05%. Table 24 — Magnesium as MgO (Surface horizon only) Diablo Clay Adobe j ytamont Clav A Loam Hani 'ord Fine S Loam A andy r % % % % % % 1-A 1.64 3- -A 1.85 14- A 2.49 2.20 1.92 1.95 1.90 2.49 2.49 2-A 2.16 4- -A 1.21 15-A 0.93 1.95 2.05 1.17 1.19 1.02 0.97 5-A 1.23 7- -A 0.09 16-A 1.10 1.03 1.13 0.05 0.07 0.99 1.04 6-A 3.62 2.90 3.26 A verage 1.05 19- A 2.11 1.99 2.05 Average 2.09 20- A 1.77 1.92 1.84 22-A 2.44 2.71 2.57 23-A 1.94 1.70 1.82 24-A 2.14 2.13 2.13 25-A 2.31 2.40 2.35 Average 1.92 1919] Pendleton: A Study of Soil Types 411 Han ford fine sandy loam. — The MgO content of the surface soil varies from 0.97% to 2.57%, averaging 1.92%. The relative varia- tion within this type is about that of the Diablo and San Joaquin types. Comparing the average amounts of magnesium oxide in the sur- face horizon of the several types, we find the San Joaquin with 0.56%, the Altamont with 1.05%, the Hanford with 1.93%, and the Diablo with 2.09%. The averages do not signify much, however, because of the wide ranges within the types. Therefore as regards magnesium the types are neither distinct nor are the soils within the type closely similar. Table 25 — Magnesium as MgO San Joaquin Sandy Loam Horizon Sample A % Average B % Average % C % Average % 10- A 0.31 0.33 0.53 0.30 0.30 0.45 0.39 0.53 0.53 11-A 0.79 1.21 1.48 0.44 0.61 1.22 1.21 1.25 1.36 12- A 0.83 0.79 1.57 0.79 0.81 0.79 1.62 1.59 13- A 0.90 1.70 1.67 0.80 0.85 1.63 1.66 1.82 1.74 17- A 0.53 0.51 No sample 0.74 0.63 0.77 0.64 18-A 0.50 0.40 0.64 0.48 0.49 0.69 0.54 0.75 0.69 21-A 0.29 0.28 0.52 0.29 0.31 0.29 0.56 0.54 26-A 0.50 0.52 0.52 0.52 0.51 0.44 0.48 0.53 0.52 Average 0.56 0.75 1.00 Phosphorus as P 2 5 Diablo clay adobe. — The variations in the P 2 5 content in the samples of this type are relatively small, from 0.092% to 0.162%, with 0.108% as the average (tables 26, 27, figs. 11-14). Altamont clay loam. — The range of variation in the amount of P 2 5 is large, from 0.031% to 0.265%, the largest quantity being eight times the smallest. The average is 0.132%. 412 University of California Publications in Agricultural Sciences [Vol. 3 San Joaquin sandy loam. — The variations in the P 2 5 content of the surface soil are from 0.039% to 0.11%, with the average 0.068%. The curve is fairly regular. The subsoils follow the surface in a gen- eral way. The B horizon samples vary in the phosphoric acid con- tent between 0.028% and 0.156%, and average 0.069%. The C sam- ples vary between 0.03% and 0.109%, and average 0.067%. The averages of the three horizons are seen to be almost identical. No particular significance can be attached to the minor variations. Hanford fine sandy loam. — The P 2 5 content in the samples of this type is very variable, from 0.195% to 0.819%, with the average of 0.363%. The average of the San Joaquin sandy loam samples is 0.069%, of the Diablo clay adobe 0.108%, of the Altamont clay loam 0.132%, and of the Hanford fine sandy loam 0.363%. Except between the Diablo and Altamont types these averages would show considerable differences, if it were not that the samples frequently show such wide departures from the averages. The ranges of the several types fre- quently overlap. Table 26 — Phosphorus as P 2 5 (Surface horizon only) Hanford Fine Sandy Diablo Clay Adobe Altamont Clay Loam Loam A . „ A . A . % % % % % % 1-A 0.088 3-A 0.278 14-A 0.373 0.096 0.092 0.252 0.265 0.292 0.333 2-A 0.064 4-A 0.081 15-A 0.287 0.078 0.071 0.117 0.099 0.260 0.273 5-A 0.137 7-A 0.034 16-A 0.260 0.082 0.109 0.028 0.031 0.277 0.268 6-A 0.143 Average 0.132 19-A 0.303 0.181 0.162 0.272 0.287 Average 0.108 20-A 0.190 0.200 0.195 22-A 0.397 0.401 0.399 23-A 0.242 0.270 0.256 24- A 0.421 0.454 0.437 25-A 0.879 0.759 0.819 Average 0.363 1919] Pendleton: A Study of Soil Types 413 Table 27- -Phosphorus as P 2 5 San Joaquin Sandy Loam Horizon A Sample A % Average % B % Average % C % Average % 10 0.118 0.060 0.047 0.102 0.110 0.068 0.064 0.057 0.052 11 0.049 0.047 0.049 0.060 0.054 0.046 0.046 0.028 0.028 12 0.057 0.028 0.064 0.071 0.064 0.028 0.095 0.078 13 0.049 0.037 0.036 0.064 0.056 0.038 0.039 0.024 0.030 17 0.036 0.041 No sample 0.042 0.039 0.082 0.061 18 0.043 0.097 0.086 0.055 0.049 0.074 0.085 0.086 21 0.069 0.088 0.094 0.068 0.068 0.066 0.077 0.062 0.078 26 0.117 0.130 0.120 0.092 0.104 0.182 0.156 0.098 0.109 Average 0.068 0.069 0.067 Potassium as K 2 Diablo clay adobe. — There is a moderate range in the variation in the amount of K 2 within this type, the lowest amount being 1.48% and the highest 2.06%, the four samples averaging 1.71% (table 28, figs. 15-18). Altamont clay loam. — A greater variation, from 1.09% to 2.14%, of K 2 0, occurs in the three samples of this type. The average is 1.74%. San Joaquin sandy loam. — This type shows the greatest variation, from 0.98% to 2.84%. But even so, the the largest quantity of K 2 is less than three times the smallest. 1.88% K 2 is the average of the eight samples. Nos. 11 and 12 of this type show the smallest amounts of K 2 of any of the twenty-four samples. Hanford fine sandy loam. — The variation in the K 2 content of the samples of this type is not great — from 1.73% to 3.16%, with the average of 2.33%. This is the highest average, as the Diablo clay adobe samples show 1.71%, the Altamont clay loam 1.74%, and the San Joaquin sandy loam 1.88%. Because of the considerable range in the amounts of K 2 for the several samples of a type, and because of the many overlappings of the values for one type over another, the averages do not mean much and do not show the soils within a type to be closely similar, nor do they show the types distinct. 414 University of California Publications in Agricultural Sciences [Vol. 3 Table 28 — Potassium as K 2 (J. Lawrence Smith Method) Hanford Fine Sandy Dii iblo Clay Adobe Altamont Clay Loam San Joaqu in Sandy Loam Loam No. % Average % Xo. % Average % No. % Average % r No. Average % 1-A 1.68 3-A 1.06 14-A 1.79 10- A 2.14 1.67 1.67 1.13 1.09 1.67 1.73 2.12 2.13 2-A 1.62 4-A 1.92 15-A 2.54 11-A 0.99 1.69 1.65 2.36 2.14 2.62 2.58 0.98 0.98 5-A 1.45 7-A 1.90 16-A 2.42 12-A 1.03 1.51 1.48 2.10 2.00 2.46 2.44 1.02 1.02 6-A 2.01 2.12 2.06 A verage 1.74 I9-A 2.10 2.03 2.06 13-A 1.50 1.50 Average 1.71 20- A 2.00 17-A 2.40 1.81 1.90 2.24 2.32 2 2-A 2.68 2.62 2.65 18-A 2.07 2.28 2.17 23-A 3.10 3.23 3.16 2 1-A 2.81 2.88 2.84 24-A 2.29 2.21 2.25 2 6-A 2.04 2.09 2.06 25-A 2.18 Average 1.88 2.21 2.19 Average 2.33 Bacteriological Data The bacteriological work was not entirely satisfactory, partly be- cause the conditions in one of the incubators were not all that might be desired, and partly because of the refractory physical properties of some of the soils. The Diablo and Altamont types, in all three horizons, were very heavy and hard to mix and keep in even fair physical condition. The San Joaquin soils were predominantly of a heavy texture in the B and C horizons, while the surface horizon was light and the crumb structure was entirely lost if even a small excess of water was added to the culture. AMMONIFI CATION There arc very marked differences between the various types in tli is determination, though the samples in a given type vary among themselves to a large extent. Diablo clay adobe. — The highest ammonia production was about three limes the lowest, 7.7 mg. and 26 mg. In both this type and the following, the B and C horizons follow the surface horizon quite 1919] Pendleton: A Study of Soil Types 415 -a £ 40 O ^ 30 n X z S 20 \ \ — - ^— N °l £ 5. 6 Soi Is. Fig. 19-A. Fig. 19a. Graph showing ammonification in the four samples of Diablo clay adobe. The quantities are expressed in terms of nitrogen produced per 100 grams of soil with 2% of dried blood. x 71 \Q 15 SO 25 \ ^ A B^^^" JZ^~ """" ~^c A Z. O 6. Soils. Fiq. 13 -B Fig. 19b. Graph showing nitrogen fixation in the three horizons of the four samples of Diablo clay adobe. The quantities are expressed in terms of milli- grams of nitrogen fixed per gram of mannite in 50 grams of soil. 416 University of California Publications in Agricultural Sciences [Vol. 3 closely from sample to sample (table 28 and fig. 19a). This may be due to the textures, which are quite similar throughout the soil column. The averages for the three horizons were : A, 18.6 mg. ; B, 12.6 mg. ; and C, 8.9 mg. 30 20 10 3 4 7 Soils Mg N. as NH3 Produced Fig. 20a. Graph showing ammonifieation in the three horizons of the three samples of Altamont clay loam. 10. 7.5 B \ \ \ V N \ \ W \ \ 2.5 3 4 7 Soils Mg N. Fixed Fig. 20b. Graph showing nitrogen fixation in milligrams in the three horizons of the three samples of Altamont clay loam. Altamont clay loam. — As regards horizon A the amount of am- monia produced in one soil is three times that in the lowest, 10 mg. nitrogen and 33 mg. nitrogen as ammonia, with 8.9 mg. as the average (table 30 and fig. 20a). The amount of nitrogen as ammonia pro- duced in the B horizon averaged 12.6 mg., in the C horizon 8.9 mg. 1919] Pendleton: A Study of Soil Types 417 San Joaquin sandy loam. — The amount of ammonia produced in the A horizon varied between 30.4 mg. of nitrogen and 57.1 mg., the average was 40.2 mg. (table 31 and fig. 21a). The production of ammonia, in milligrams of nitrogen, by the B samples varied between 4.5 mg. and 38.1 mg., with 20 mg. as the average. In the C samples the variation was nearly as great, between 5.7 mg. and 32 mg., with the average of 20.9 mg. Thus there are notable variations among the 12 13 17 18 21 26 Soils Mg N. as NH3 produced Fig. 21a. Graph showing ammonification in the three horizons of the eight samples of San Joaquin sandy loam. samples of this type, the proportional variation being very great, con- sidering the three horizons. Possibly the reason that the B and C horizons are so divergent from the surface is that there is a very marked variation in the texture between the surface horizon and those below the surface. Hanford fine sandy loam. — The variation is large here also (table 32, fig. 22a), the largest quantity of ammonia produced in the surface soil is twice that of the smallest production, 72 mg. and 35 mg. The subsoil variations, in a general way, parallel those of the surface. The average production of ammonia in the three horizons is as fol- 418 University of California Publications in Agricultural Sciences [Vol. 3 lows: A, 56.9 mg. nitrogen; B, 46.3 mg. nitrogen; and C, 38.7 mg. nitrogen. In attempting to correlate the variations in ammonifying powers with the known variations of the soils, or with the known his- tories of the soils, there seem to be no relations of significance. The Altamont and Diablo types are about alike in their low am- monifying power. The Hanford and San Joaquin are both higher and nearer to each other than to the two heavy types, yet the Hanford is noticeably higher than the San Joaquin. This is as one would ex- pect, from a knowledge of the soils in the field. Considering the types as a whole, as represented by the A horizon, there are more marked variations between the types than between the samples of a given type though the variations within a given type are very large. Average Table 29 — Ammonification Diablo Clay Adobe Milli grams N as NH 3 Pi -oduced A A B C ( Cultures Checks average Increase over checks Cultures Checks average Increase over checks r Cultures Increase Checks over average checks 31.48 28.58 24.24 40.32 2.52 33.38 22.98 2.28 23.50 14.99 2.42 17.19 19.81 9.45 8.41 17.07 1.68 16.76 9.84 1.91 7.73 9.95 1.05 8.13 15.90 11.55 No sample 1.75 14.15 12.54 1.54 10.50 12.33 7.76 12.33 3 2.11 10.22 18.63 13.55 2.07 8.58 12.58 12.33 2.03 10.30 11.87 Table 30 — Ammonification Altamont Clay Loam Milli; grams N as NH 3 Pi reduced A A B A C Sample r Cultures Checks average > > Increase over checks Cultures Checks average Increase over checks Cultures Checks average > Increase over checks 3 8.14 6.97 5.89 10.58 1.68 7.68 7.15 1.40 5.16 4.91 1.54 3.86 4 19.75 6.59 5.41 19.12 2.66 16.77 6.67 1.36 5.27 5.12 1.19 4.07 7 28.66 19.66 8.00 27.53 2.03 26.06 1 6.25 1.75 16.20 12.37 1.33 8.95 Average 16.84 8.88 5.63 1919] Pendleton: A Study of Soil Types 419 Table 31 — Ammonification San Joaquin Sandy Loam Milligrams N as NH 3 Produced B Sample 10 Cultures 54.24 Checks average Increase over checks r Cultures 42.63 Checks average Increase over checks r Cultures 28.89 1 Checks average > ncrease over checks 41.95 1.72 46.73 36.11 1.28 38.09 38.25 1.59 31.98 11 44.47 7.47 6.05 73.23 1.70 57.15 12.52 1.81 8.18 6.78 1.68 4.78 12 44.48 18.73 10.91 40.07 1.56 40.71 21.81 1.50 18.77 6.11 1.14 7.87 13 41.66 5.41 3.80 45.04 1.30 42.50 5.36 0.86 4.52 15.17 0.88 8.60 17 30.19 27.59 No sample 33.88 1.66 30.37 20.68 1.51 22.62 18 35.04 30.56 21.96 35.24 1.48 33.66 22.81 1.30 25.38 16.92 1.47 17.97 21 34.44 37.41 25.72 30.89 1.48 31.18 37.74 1.38 36.19 29.66 1.42 26.27 26 40.81 7.50 9.08 1.64 39.17 8.41 1.44 6.51 5.43 1.54 5.71 A vera s :e 40.18 20.03 12.89 Table 32 — Ammonification Hanford Fine Sandy Loam Milligrams N as NH 3 Produced B Sample Cultures Checks average Increase over checks r Cultures Checks average Horizons Increase over checks r Cultures Checks average Increase over checks 14 37.35 27.96 14.39 43.57 1.78 38.68 48.46 1.46 36.75 41.70 1.24 26.80 15 33.11 45.68 59.90 41.75 1.75 35.68 48.38 1.70 45.33 52.59 1.62 54.62 16 56.59 44.08 44.58 56.77 1.83 54.85 42.10 1.61 41.48 52.10 1.69 46.65 19 52.92 46.70 24.56 51.85 1.47 50.91 38.92 1.13 41.68 28.12 1.24 25.10 20 72.49 45.49 22.05 74.21 1.36 71.99 38.52 1.03 40.97 30.35 1.00 25.20 22 64.92 57.44 46.08 67.56 1.75 64.49 55.34 1.51 54.88 47.55 1.60 45.21 23 71.56 50.84 35.15 68.66 1.61 68.50 43.01 1.37 45.55 35.23 1.35 33.84 24 65.02 50.09 37.56 59.51 1.50 60.76 46.54 1.32 46.99 40.21 1.33 37.55 25 68.20 69.29 61.01 67.29 1.43 66.31 60.03 1.25 63.41 47.70 1.22 53.13 Average 56.91 46.34 38.67 420 University of California Publications in Agricultural Sciences [Vol. 3 Nitrogen Fixations Diablo clay adobe. — This type shows the highest quantity of nitro- gen fixed, 9.6 m'g., with the subsoil quantities, much lower than the surface. The variation within the type is seen to be the largest of that in any of the types. Altamont clay loam. — The surface samples have 1.0, 4.7, and 9.1 mg. nitrogen (table 34 and fig. 20b). The soils shows a wide diver- gence between the surface samples and between the surface and sub- soils. This is to be expected in the heavier soils. 7.5 C 2.3 \ \ 7* \ \ \ \ \ \ \ X ______ _^^+ ^ 10 11 12 13 17 Mg N. Fixed IS 21 26 Soils Fig. 21b. Graph showing nitrogen fixation in the three horizons of the eight samples of San Joaquin sandy loam. San Joaquin sandy loam. — The quantity fixed in the A horizon (table 35 and fig. 21b) is small and quite variable. It is between nothing and 5.5 mg., with the average of 1.9 mg. Instead of nitrogen fixation denitrification took place in a number of cases, especially in horizon C. Considering the wide variation in textures of the horizons, it is rather odd that there should not be a greater variation between the soils from the various depths. Han ford fine sandy loam. — The amount of nitrogen fixed by the surface soil (table 36, and fig. 22b) averages much higher, 5.7 mg., than that in the San Joaquin sandy loam, though the range of varia- tion is about the same. It is noticeable that the amounts of nitrogen fixed by the B and C horizons of the soils nos. 14 and 19 are much 28 All of the figures on nitrogen fixation refer to the milligrams of nitrogen fixed per gram of mannite in 50 grams of soil (table 33 and figs. 9-13). 1919] Pendleton : A Study of Soil Types 421 less (even to denitrification) absolutely and relatively as compared with the surface horizons, than the amount fixed by the B and C horizons of the soils nos. 20 to 25 inclusive. Comparing the nitrogen fixation of the various types, there seem to be no characteristic differences between the heavy Altamont and Diablo types, while the lighter Hanford and San Joaquin types are considerably different from each other. As a whole there is but a fair degree of similarity between the samples of a given type. The degree of variation within types is large. Table 33 — Nitrogen Fixation Diablo Clay Adobe Millisri ams N per gram of mannite A A B A C A Sample f Cultures Checks average Increase over checks Cultures Checks average Increase over checks r Cultures Checks average Increase over checks 1 60.25 31.52 22.77 63.40 52.22 9.60 29.56 34.67 -4.13 24.87 28.61 -4.79 2 55.34 32.92 30.47 49.39 45.88 6.48 38.18 33.80 1.75 32.22 29.77 1.57 5 48.68 35.73 No sample 48.68 41.92 6.76 37.12 32.39 4.03 6 45.88 39.64 35.02 46.86 58.49 -12.12 42.72 50.77 -9.59 39.01 39.05 -2.03 Average 4.71 1.44 0.52 Table 34 — Nitrogen Fixation Altamont Clay Loam Milligrams N fixed per gram of mannite B Sample Cultures Checks average Increase over checks r Cultures Checks average Increase over checks r Cultures Checks average Increase over checks 3 71.26 49.04 37.13 70.40 61.71 9.12 51.84 43.78 6.66 38.51 33.76 . 4.06 4 60.25 28.02 20.31 52.19 51.49 4.73 27.32 26.48 1.19 21.01 20.48 0.18 7 52.95 37.75 30.81 53.44 52.12 1.08 37.40 36.60 1.00 27.18 29.94 -0.94 Average 4.98 2.95 1.41 422 University of California Publications in Agricultural Sciences [Vol. 3 7d :.o 40 30 20 10 . /^/ 1 1 1 N / N / S / / \ \ / /'« / / t 1 1 1/ / \ \ \ — *— / / , / / X \ \ \ N \ -— -"" / / / / / / / / / \ \ \ \ \ \ / / / / / / \ \ \ \ ^" / / < \ \ > / / - 15 16 23 24 19 20 22 Mg N. as NH3 produced Fig. 22a. Graph showing ammonification in the three horizons of the nine samples of Hanford fine sandy loam. 26 Soils 10 7.5 2.5 // \\ \\ / >< s // / / / 1 l \ 23 21 15 16 19 20 22 Mm N. Fixed Pig. 22b. Graph showing nitrogen fixation in the three horizons of the nine sum pies of Hanford fine sandy loam. 25 Soils 1919] Pendleton: A Study of Soil Types 423 Table 35 — Nitrogen Fixation San Joaquin Sandy Loam Milligrams N fixed per gram of mannite A A B A C Sample Cultures Checks average Increase over checks r Cultures Checks average Increase over checks r Cultures Checks average Increasi over checks 10 25.01 17.16 15.83 23.47 18.73 5.51 16.67 13.59 3.32 18.14 10.33 6.65 11 27.25 22.91 21.72 31.87 25.15 4.41 22.84 21.78 1.09 22.00 19.43 2.43 12 25.85 20.17 18.98 23.82 23.26 1.57 17.09 16.56 2.07 20.10 20.41 -0.87 13 22.77 18.49 13.31 21.58 20.00 2.17 17.86 20.21 -2.04 14.50 16.35 -2.45 17 13.52 13.45 9.46 10.23 No samp] [e 18 15.55 8.76 9.18 13.24 13.73 0.66 8.20 8.09 0.39 11.42 9.74 0.56 21 14.85 7.98 6.58 16.11 14.50 0.98 6.44 5.96 1.25 7.28 7.01 -0.07 26 19.54 12.61 7.14 19.34 20.34 -0.94 12.82 13.34 -0.72 7.36 8.24 -0.99 Av erage 1.91 1.09 1.20 Table 36 — Nitrogen Fixation Hanford Fine Sandy Loam Milligrams N fixed per gram of mannite A A B C A Sample r Cultures Checks average Increase over checks r Cultures Checks average ^ Increase over checks r Cultures Checks average Increase over checks 14 71.52 41.61 31.10 63.05 59.61 7.67 41.69 41.01 0.64 30.19 29.07 1.57 15 38.18 22.07 12.40 29.56 26.55 7.32 21.09 20.12 1.46 14.08 13.87 -0.63 16 30.33 16.46 9.67 32.92 27.84 3.78 16.04 14.85 1.40 8.97 10.61 -1.29 19 25.56 14.43 11.77 26.41 22.49 4.49 13.59 12.29 1.72 12.33 11.80 -0.25 20 38.04 22.84 17.09 38.11 29.66 8.41 23.61 16.39 6.83 20.60 11.52 7.32 22 35.59 22.20 17.30 31.80 29.17 4.52 23.40 17.23 5.57 16.46 11.87 5.0T 23 38.95 19.19 11.90 43.57 36.10 5.16 20.25 14.57 5.15 11.98 8.90 3.04 24 28.79 19.89 18.52 34.61 25.67 6.03 21.52 16.95 3.75 17.51 13.91 4.11 25 26.55 17.86 15.55 26.41 22.70 3.78 17.93 15.51 2.38 13.87 11.31 3.41 Average 5.69 3.21 2.27 424 University of California Publications in Agricultural Sciences [Vol.3 NITRIPICATION29 The most noticeable thing about the nitrification results is the very wide range of variation in the various representatives of the Hanford fine sandy loam as compared with the quite uniform and consistent results obtained with the other types. Diablo clay adobe. — The percentage of nitrogen nitrified (table 37, 38, and fig. 23) is uniformly low. The B samples showed a less vigorous nitrifying flora (except in the case of no. 6) than the sur- face ones. Dried blood in the quantities used seems to depress the A S. N.+ Cottonseed Meal -A S. N.+ (NH 4 ) 2 S04 A S. N. + Dried Blood A Soil Nitrogen 12 5 6 Soils Percentages of N. Nitrified Fig. 23. Graph showing the percentages of nitrogen in various nitrogen containing materials nitrified in the four samples of the Diablo clay adobe. normal activity (A horizon average 0.81%), while the (NH 4 ) 2 S0 4 (A horizon average 3.03%) and the cottonseed meal (A horizon average 2.91%), as compared with the incubated control tend to in- crease the percentage of nitrogen nitrified. It should be kept in mind that an absolute increase in the nitrogen content may accompany a decrease in the percentage, due to the greatly increased amount of nitrogen present after the addition of a nitrogenous substance. The variation of the samples within this type is very moderate as compared with the San Joaquin and Hanford types. 29 The figures used in the discussion shows the percentages of the nitrogen in the cultures which were nitrified. There are two tables for the samples of each type. The percentages of nitrogen nitrified are rearranged in a second table for greater ease in comparing results. 1919] Pendleton: A Study of Soil Types 425 Altamont clay loam. — The percentages of nitrogen nitrified (tables 39 and 40, fig. 24) are as a whole lower than in the Diablo soils. A similar relative effect of the several nitrogenous materials is seen, for (NH 4 ) 2 S0 4 is first, cottonseed meal, second, the soil's own nitrogen third, and dried blood fourth in the percentages of nitrates produced. As in the Diablo soils the variation is not great from soil to soil. San Joaquin sandy loam. — A wide range of variation (tables 41, 42, and fig. 25), from 1.2% £o 4.5%, is found in the incubated control, possibly due, in part, to the considerable variations in the physical nature of the samples. The relative action of the nitrogenous ma- A S. N.+ (NH 4 ) 2 S04 A S. N. +Cottonseed Meal A Soil Nitrogen A S. N. + Dried Blood 4 7 Soils Percentages of N. Nitrified Fig. 24. Graph showing the percentages of nitrogen in various nitrogen containing materials nitrified in the three samples of the Altamont clay loam. terials in the soils of the San Joaquin samples as compared with that in the Diablo and Altamont soils is well shown by the following aver- ages of the A horizon: dried blood had 0.02%. cottonseed meal had 0.33%, and ammonium sulfate had 0.56% of the nitrogen nitrified, while the incubated control had 2.47% nitrified. The soils are normally low in nitrogen, and this, together with the poor physical condition, made an unfavorable medium for any bacterial activity. This applies especially to horizons B and C. Han ford fine sandy loam. — This is by far the most inexplicable set of results in the nitrification studies (tables 43, 44, and fig. 26). The physical nature of this type is admirably suited for bacteriological tumbler cultures, the soil being friable, not puddling readily, and while in the incubator may be kept at the approximately optimum moisture content with little difficulty. This property is fairly con- 426 University of California Publications in Agricultural Sciences [Vol. 3 stant throughout all the samples (except no. 14) and cannot well be supposed to affect the results greatly. No. 14 has a low nitrifying power throughout, but it is not representative of the type, for it is heavier in texture than the rest. Moreover, it had been submerged by river overflows shortly before the collection of the sample. One would expect these factors to influence the numbers and the activity of the bacterial flora. There is but little similarity in the way the different samples of the A or B horizons behave toward any given / -— _ \ / / \ \ / \ / / \ / / \ \ / / \ ^ v^ \ ""•N '^^" A. Soil Nitrogen A. S. N.+ (NHO2SO4 S. N. -{-Cottonseed Meal 10 12 21 26 Soils 13 17 18 Percentages of N. Nitrified Fig. 25. Graph showing the percentages of nitrogen in various nitrogen containing materials nitrified in the eight samples of the San Joaquin sandy loam. nitrogen containing material. Variations from 1% to 50%, from 0% to 14%, from 4.5% to 8%, or from 15% to 15.5% from soil to soil, without regularity, give slight basis for generalizations. The average effect of the A horizon samples of the Hanford fine sandy loam as regards the several nitrogenous materials is as follows : dried blood, 5.62%; cottonseed meal, 13.72%; ammonium sulfate, 3.29%; incubated control, 1.55%. In a general way there is a similarity between the effects of a given nitrogen containing material on the surface sample, and on the B horizon. This should be so, since these soils are very deep and uniform in texture. However, in the C horizon there were still greater decreases in the bacterial activity. 1919] Pendleton: A Study of Soil Types 427 As regards nitrification in general there is difficulty in showing any greater resemblance between the samples of a type than there is from type to type. In certain features, however, the types are some- what distinct : ( 1 ) The relation of the nitrification of the soil 's own nitrogen to the soil's action upon added nitrogen is rather distinct for the types. The normal soil in the San Joaquin type gave a much larger per cent of nitrogen than did the soil plus the added nitrogen containing materials. In the Diablo type (fig. 25) the normal soil was about midway in its production as compared with the soils to which the nitrogenous materials were added. In the Hanford fine sandy loam the normal soils gave a much lower percentage nitrifica- tion than in the greater number of instances where the soils were treated with nitrogenous materials. (2) The relative nitrification of the various nitrogenous materials is somewhat distinct for the types. The Diablo, Altamont, and San Joaquin show the ammonium sulfate first, with the cottonseed meal second, and the dried blood third. The Hanford type shows cottonseed meal first, with dried blood second and ammonium sulfate third. Table 37 — Nitrification Diablo Clay Adobe Soil nitrogen a Soil nitrogen and ammonium sulfate A Soil nitrogen : dried blood A and Soil nitrogen and cottonseed meal A Sample 6 si 11 o w . a. bfl 'as _, o Eh > si 6 si ®tJ « s u $ 0) d£ O li o si to • a> Suo o.S 6H O U o si si £•1 « w o.S za g' 5 1-A 0.90 104.43 0.86 5.35 146.82 3.65 2.20 347.22 0.63 5.00 198.42 2.50 1-B 0.28 93.34 0.30 0.77 135.74 0.57 Tr. 336.14 Tr. 187.34 1-C 0.19 57.22 0.33 0.25 99.62 0.25 0.07 300.02 0.02 0.16 151.22 2-A 0.47 91.76 0.51 3.47 134.16 2.58 4.07 334.56 1.22 6.82 185.76 3.77 2-B 0.33 67.60 0.49 1.17 110.00 1.06 0.08 310.40 0.19 161.60 0.12 2-C 0.59 59.54 0.29 101.94 0.80 302.34 0.80 153.54 5-A 0.47 83.82 0.56 3.81 126.22 3.02 1.66 326.62 0.51 3.76 177.82 2.12 5-B 0.36 64.78 0.56 0.42 107.18 0.39 0.19 307.58 0.06 0.97 158.78 0.61 6-A 0.59 116.58 0.51 6-B 1.65 101.54 1.63 6-C 0.96 78.10 1.23 4.58 158.98 2.88 3.00 143.94 2.08 1.01 120.50 0.84 3.13 359.38 0.87 1.19 344.34 0.35 0.37 320.90 0.01 6.88 210.58 3.26 4.55 195.54 2.32 0.47 172.10 0.27 I 428 University of California Publications in Agricultural Sciences [Vol. 3 55 oil 1 \ 4o \ \ 40 \ \ 35 \ 1 o! ) \ 1 J.J \ 1 20 \ 1 1.) \ 1 ! \ Jo \ \ s 5 -^ s / \ / \ s s . -v 15 L6 23 24 Fig. 26. containing loam. 17 20 22 Percentages of N. Nitrified Graph showing the percentages of nitrogen in various nitrogen materials nitrified in the nine samples of the Hanford fine sandy A S. N. + Cottonseed Meal ^ A S. N.+ (NH 4 ) 2 S04 A Soil Nitrogen A S. N. + Dried Blood 25 Soils 1919] Pendleton: A Study of Soil Types 429 Sample 1 2 5 6 Average A 0.86 0.51 0.56 0.51 0.61 Table 38 — Nitrification — Percentages of Nitrogen Nitrified Diablo Clay Adobe Soil nitrogen and Soil nitrogen Soil nitrogen Soil nitrogen ammonium sulfate and dried blood cottonseed meal — * , , a * , a ; , a * BC ABC ABC ABC 0.30 0.33 3.65 0.57 0.25 0.63 0.02 2.50 0.49 2.58 1.06 1.22 3.77 0.12 0.56 3.02 0.39 0.51 0.06 2.12 0.61 1.63 1.23 2.88 2.08 0.84 0.87 0.35 0.01 3.26 2.32 0.27 0.74 0.52 3.03 1.02 0.36 0.81 0.10 0.01 2.91 0.76 0.09 Table 39 — Nitrification Altamont Clay Loam So il nitrogei A i Soil nitrogen and ammonium sulfate Soil nitrogen and dried blood A Soil nitrogen and cottonseed meal A 6 &i CO • eg u S CD a> be 6 tx CD CD fafi 6 tx CD tffl 0- fcJD $ J--T3 Sample If _ O ^3 cc o h ®T3 _ o O U 1* Is _ o Is M o.S Eh o u IS ^_ o • ©.a 3-A 0.60 123.42 0.49 4.12 165.82 2.49 1.17 366.22 0.32 3.57 217.42 1.64 3-B 0.04 87.56 0.05 0.39 129.96 0.32 0.18 330.36 0.03 181.56 3-C 0.27 67.52 0.40 0.20 109.92 0.18 0.10 310.32 0.10 161.52 4-A 1.30 102.58 1.27 2.95 144.98 2.05 2.34 345.38 0.68 4.83 196.58 2.46 4-B 0.45 52.96 0.85 95.36 0.10 295.76 146.96 4-C 40.96 83.36 283.76 0.20 134.96 0.15 7-A 0.50 104.24 0.48 1.35 146.64 0.93 0.40 347.04 0.12 1.27 198.24 0.64 7-B 0.25 73.20 0.34 0.32 115.60 0.28 316.00 167.20 7-C 59.88 102.28 302.68 153.88 Table 40 — Nitrification — Percentages of Nitrogen Nitrified Altamont Clay Loam Soil nitrogen ABC Soil nitrogen and ammonium sulfate A Soil and d: nitrogen ried blood Soil nitrogen and cottonseed meal A Sample A B ^ c A B C A B C 3 0.49 0.05 0.40 2.49 0.32 0.18 0.32 1.64 4 1.27 0.85 2.05 0.68 2.46 0.15 7 0.48 0.34 0.93 0.28 0.12 0.64 Average 0.75 0.41 0.13 1.82 0.20 0.06 0.37 1.58 0.05 430 University of California Publications in Agricultural Sciences [Vol. 3 Table 41 — Nitrification San Joaquin Sandy Loam Soil nitrogen Soil nitrogen and ammonium sulfate Soil nitrogen and Iried blood Soil nitrogen and cottonseed meal A Sample 10- A O bi 0.52 a3 a> bi &a _ o n * Eh 37.46 o u u *> 1.4 o si s a 0.24 03 • a> bSt 'aa |.a 122.26 %8 y p U 0.2 6 si is 0.06 Xfl • Average weight r Weight Average weight Notes 1-1 6 8.48 0.29 8.77 1-2 6 8.58 0.06 8.64 1-3 6 6.87 7.98 0.41 0.25 7.28 8.23 2-1 6 2.12 2.12 Excluded from 2-2 4 3.62 0.40 4.02 average 2-3 5 6.07 4.84 0.38 0.39 6.45 5.23 5-1 6 5.84 0.16 6.00 5-2 6 7.96 0.64 8.60 5-3 6 6.47 6.76 0.69 0.49 7.16 7.25 6-1 6 7.61 0.24 7.85 6-2 6 7.99 0.45 8.43 6-3 6 7.26 7.62 0.17 0.28 7.43 7.90 Altamont clay loam. First crop. — The crops planted in this soil were wheat, barley, oats, bur clover, Phaseolus, and oats and bur clover together. The standard number to which the plants were thinned was six, except in the oats and bur clover series, where three plants of each were allowed to remain. With regard to the comparative crop producing power of these soils under these conditions, soil no. 4 is the best, with soil no. 3 as the second, and soil no. 7 was the poorest (tables 56-60, fig. 29). The dry weight data decidedly corroborate the impression given by the greenhouse appearance of the crops. However, as all the crops were so small on all the series, the figures do not show as much as they might have shown had the growth been more nearly optimum for the several crops. Table 56 — Altamont Clay Loam, First Crop Wheat Planted, February 25, 1916. Harvested, July 10, 1916 Notes No. plants Straw A Grain A Total dr Weight y matter A Pot Weight Average weight Weight Average weight Average weight 3-1 6 2.62 1.23 3.85 3-2 6 2.93 1.09 3.92 3-3 6 2.86 2.80 1.04 1.12 3.91 3.92 4-1 6 4.20 1.78 5.97 4-2 6 4.03 1.22 5.25 4-3 6 6.20 4.81 1.13 1.38 7.34 6.19 7-1 6 2.64 1.11 3.76 7-2 6 2.58 0.99 3.64 7-3 6 2.90 2.71 0.71 0.93 3.61 3.64 442 University of California Publications in Agricultural Sciences [Vol. 3 Table 57 — Altamont Clay Loam, First Crop Barley Planted, April 4, 1916. Harvested, July 11, 1916 No. plants St raw Grain Total dr r Weight y matter Pot f Weight Average weight Weight Average weight Average weight 3-1 1.10 0.76 1.86 3-2 1.45 1.40 2.85 3-3 1.39 1.31 1.18 1.11 2.57 2.43 4-1 1.99 1.43 3.42 4-2 1.90 1.57 3.47 4-3 2.39 2.09 1.85 1.62 4.25 3.71 7-1 0.98 0.90 1.88 7-3 1.06 1.00 0.59 0.71 1.64 1.71 Notes Table 58 — Altamont Clay Loam, First Crop Oats Planted, February 25, 1916. Harvested July 11, 1916 No. plants 6 SI raw A Grain Total dry matter Pot 3-1 r Weight 1.36 Average weight r Weight 0.38 Average weight Weight 1.74 Average weight 3-2 6 1.60 0.67 2.27 3-3 6 1.70 1.55 0.47 0.51 2.17 2.06 4-1 6 3.05 1.42 4.47 4-2 4 2.62 1.13 3.76 4-3 4 3.46 3.04 1.81 1.45 5.27 4.50 7-1 6 1.21 0.29 1.51 7-2 6 1.00 0.42 1.42 7-3 6 0.88 1.03 0.35 0.35 1.23 1.38 Notes Table 58 — Altamont Clay Loam, First Crop Bur Clover Planted, February 25, 1916. Harvested, July 8, 1916 No. plants 6 Straw A Gi *ain Total dr r Weight 2.53 y matter Pot 3-1 r Weight 1.50 Average weight Weight 1.03 Average weight Average weight 3-2 6 0.88 1.17 2.18 3-3 6 0.63 1.00 1.34 1.18 1.96 2.18 4-1 6 2.48 1.47 3.95 4-2 6 2.57 1.57 4.14 4-3 4 2.50 2.52 1.31 1.45 3.81 3.97 7-1 6 0.47 0.66 1.13 7-2 6 0.53 0.24 0.78 7-3 6 0.37 0.46 0.20 0.36 0.57 0.82 Notes 1919] Pendleton: A Study of Soil Types 443 Table 59 — Altamont Clay Loam, First Crop Oats and Bur Clover Planted, April 14, 1916. Harvested, July 8, 191 No. plants Straw A Grain A Total di height •y matter K Pot r Weight "\ r Average weight Weight > r Average weight V\ Average weight 3-1 B.C. 3 0.98 1.25 2.23 Oats 3 0.77 0.10 0.88 3-2 B.C. 4 0.79 1.17 1.96 Oats 4 0.68 0.22 0.90 3-3 B.C. 4 0.48 0.91 1.38 Oats 4 0.78 1.49 0.30 1.32 1.07 2.81 4-1 B.C. 3 0.67 0.32 0.99 Oats 3 2.42 1.75 4.17 4-2 B.C. 3 0.40 0.62 1.01 Oats 3 2.63 1.38 4.01 4-3 B.C. 3 0.51 0.21 0.72 Oats 3 2.77 3.14 1.09 1.78 3.86 4.92 7-1 B.C. 3 0.20 0.27 0.47 Oats 3 0.86 0.74 1.60 7-2 B.C. 3 0.28 0.22 0.50 Oats 3 1.27 0.95 2.22 7-3 B.C. 4 0.42 0.37 0.74 Oats 2 0.64 1.22 0.44 0.98 1.08 2.20 Notes Table 60 — Altamont Clay Loam, First Crop Beans (Phaseolus) Planted, February 25, 1916. Harvested, July 11, 1916 No. plants Straw A Grain Total dr; Weight y matter Pot Weight Average weight r Weight Average weight Average weight 3-1 6 2.82 0.13 2.96 3-2 6 1.24 0.35 1.59 3-3 6 1.32 1.79 0.32 0.27 1.64 2.06 4-1 5 1.71 0.25 1.96 4-2 6 1.41 0.59 2.01 4-2 6 1.81 1.64 0.59 0.48 2.41 2.12 7-1 1 0.11 0.09 0.20 7-2 6 0.53 0.53 7-3 5 0.63 0.43 0.03 0.63 0.46 Notes Altamont clay loam. Second crop. — A slightly different scheme was used in the planting of this series, only three crops were used, i.e., soy beans, cowpeas, and milo. Two sets of pots were planted to each crop, one of the two sets having previously been planted to a legume, and the other to a non-legume. The milo was thinned so that 444 University of California Publications in Agricultural Sciences [Vol. 3 one pot of each triplicate set would have 8 plants, the second of the set 12 plants, and the last 16 plants. It was found that the wide variation in the number of plants had but little effect upon the dry weight produced per pot (tables 61-66). The effect was indeed so slight that the totals were averaged up as usual. Figure 30 shows distinctly that there was very little variation as regards total produc- tion among these soils, so little as not to warrant any conclusions as regards substantiation of, or disagreement with, the first crop. It will be noticed in the second crop of the Diablo series, as well as in that of the Altamont series, that the maintenance of the soils under the same conditions for a year or more seems to bring them quite rapidly to an average crop producing power. Table 61 — Altamont Clay Loam, Second Crop Milo A (following wheat) Planted, August 10, 1916. Harvested, November 17, 1916 Straw Grain Total dry matter No. Average Average Average Pot plants Weight weight Weight weight Weight weight Notes 3-1 8 0.77 0.77 3-2 12 1.01 1.01 3-3 16 0.97 0.92 0.97 0.92 4-1 8 1.22 1.22 4-2 12 2.32 2.32 4-3 16 2.08 1.87 2.08 1.87 7-1 8 0.59 0.59 7-2 12 0.99 1.29 7-3 16 1.29 0.95 1.29 0.95 Table 62 — Altamont Clay Loam, Second Crop Milo B Planted, August 10, 1916. Harvested, November 15, 1916 Straw Grain Total dry matter . A . . A . , A . t ^ r ^> f \ Average Average Average Weight weight Weight weight Weight weight Notes 0.82 0.82 1.13 1.13 1.15 1.03 1.15 1.03 1.28 1.28 1.82 1.82 1.45 1.52 1.45 1.52 0.66 0.66 0.96 0.96 0.02 0.85 0.92 0.85 Pot No. plants 3-1 8 3-2 12 3-3 16 4-1 8 4-2 12 4-3 16 7-1 8 7-2 12 7-3 10 1919] Pendleton: A Study of Soil Types 445 Table 63 — Altamont Clay Loam, Second Crop Cowpeas A (following barley) Planted, August 10, 1916. Harvested, November 17, 1916 Straw Pot No. plants r Weight Average weight 3-1 6 3.48 3-2 6 4.50 3-3 6 3.00 3.66 4-1 6 2.44 4-2 6 2.59 4-3 6 3.40 2.81 7-1 6 2.64 7-2 6 1.93 7-3 6 2.15 2.24 Grain A Average Weight weight Total dry matter Weight Average weight 3.48 4.50 3.00 3.66 2.44 2.59 3.40 2.81 2.64 1.93 2.15 2.24 Notes Table 64 — Altamont Clay Loam, Second Crop Cowpeas B (following oats and bur clover) Planted, August 10, 1916. Harvested, November 14, 1916 Straw Grain Total dry matter Pot No. plants Weight Average weight Average Weight weight r Weight Average weight 3-1 6 4.16 4.16 3-2 6 3.63 3.63 3-2 6 2.77 3.52 2.77 3.52 4-1 6 3.35 3.35 4-2 6 2.70 2.70 4-3 6 1.94 2.66 1.94 2.66 7-1 6 1.51 1.51 7-2 6 2.10 2.10 7-3 6 2.85 2.15 2.85 2.15 Notes Table 65 — Altamont Clay Loam, Second Crop Soy Beans A (following oats) Planted, August 10, 1916. Harvested, November 17, 1916 Straw Grain Total drv matter , A . A . A . t "\ t \ t \ No. Average Average Average Pot plants Weight weight Weight weight Weight weight 3-1 6 4.85 4.85 3-2 6 4.25 4.25 3-3 6 4.50 4.53 4.50 4.53 4-1 6 3.53 3.53 4-2 6 3.59 3.59 4-3 6 4.88 4.00 4.88 4.00 7-1 6 3.42 3.42 7-2 6 3.34 3.34 7-3 6 3.42 3.39 3.42 3.39 Notes 446 University of California Publications in Agricultural Sciences [Vol. 3 Table 66 — Altamont Clay Loam, Second Crop Soy Beans (following Phaseolus) Planted, August 10, 1916. Harvested November 17, 1916 Straw Grain Total dry matter . . A . . A . . A „ r \ f \ r \ No. Average Average Average Pot plants Weight weight Weight weight Weight weight Notes 3-1 6 5.64 5.64 3-2 6 4.94 4.94 3-3 6 4.84 5.14 4.84 5.14 4-1 6 4.74 4.74 4-2 6 4.64 4.64 4-3 6 4.71 4.70 4.71 4.70 7-1 6 5.25 5.25 7-2 6 3.28 3.28 7-3 6 4.39 4.31 4.39 4.31 Hanford fine sandy loam. First crop. — This soil type, with sam- ples from nine different localities in California, gave a much wider range of conditions and made a much more interesting series. The plants used as indicators in this series were milo (twice), millet, cow- peas (twice), and soy beans. The milo was thinned to eight plants per pot, the millet to twelve plants, and the cowpeas and soy beans to six plants. Set A of cowpeas, and set B of milo were unfavorably located, so that the results of these sets should be discounted. It is interesting to note the large differences in the average weights from soil to soil (tables 67-72, and fig. 31), as compared with the photographs, in which little variation appears. See especially the soy bean series. In this series two things are to be noted : 1. Averages on soils nos. 15 and 25 are hardly representative be- cause in both cases excess moisture, from a leaky roof and too heavy watering, depressed growth. The tendency to become compact and to remain wet and cold shown by soil no. 15 aided the milo and depressed the soy beans. 2. The loose, open texture of soil no. 22 seemingly favored the soy bean growth, though the other plants did not do as well on this soil as on most of the others. 1919] Pendleton: A Study of Soil Types 447 Comparing the more satisfactory grains, milo A and millet, it will be seen that there is somewhat of a parallelism from soil to soil. The legumes do not always respond similarly to the grains, as in the Diablo first crop, yet in the Diablo second crop and the Altamont first and second crops the response of grain and legume seems quite similar. Hence, it is not safe in every case to judge as to the relationships shown by legumes and non-legumes. SqyB^o/* Fig. 31 Fig. 31. Graph showing the total dry matter produced by millet, milo (two series), cowpeas (two series), and soy beans on the nine samples of Hanford fine sandy loam. First crop. Considering all the variations, one might say that soil no. 23 was seemingly among the better soils, and soils nos. 16 and 22 among the poorer soils. Yet when discussing whether the soils be the same or similar, according to the criterion of the dry weight, one of the Han- ford groups will be similar according to one crop, and an overlapping group similar according to the second crop. It can be said with rea- sonable certainty that these Hanford soils are not closely similar to one another. 448 University of California Publications in Agricultural Sciences [Vol. 3 Pot 14-1 14-2 14-3 15-1 15-2 15-3 16-1 16-2 16-3 19-1 19-2 19-3 20-1 20-2 20-3 22-1 22-2 22-3 23-1 23-2 23-3 24-1 24-2 24-3 25-1 25-1 25-2 25-3 No. plants Table 67 — Hanford Fine Sandy Loam, First Crop Milo A Planted, June 10, 1916. Harvested, November 18, 1916 Straw Grain Total dry matter „ A A . . A ( \ r \ r \ Average Average Average Weight weight Weight weight Weight weight Notes 15.34 15.34 Most plants bore 12.50 12.50 no grain; some 10.15 12.66 10.15 12.66 ^ rain was im - mature at har- vest. These cases noted, but no grain weighed. 13.14 13.14 14.50 14.50 15.21 14.28 15.21 14.28 Not mature 8.67 8.67 5.86 5.86 4.76 6.43 4.76 6.43 7.65 7.65 14.11 14.11 7.01 7.01 14.10 14.10 10.15 10.15 7.68 10.64 7.68 10.64 Not mature 5.34 5.34 5.88 5.88 5.35 5.52 5.35 5.52 8.90 8.90 Not mature 10.04 10.04 Not mature 8.67 9.20 8.67 9.20 10.82 10.82 9.92 9.92 Not mature 6.01 8.92 6.01 8.92 Not mature 11.26 11.26 11.26 11.26 5.70 5.70 9.33 8.76 9.33 8.76 1919] Pendleton: A Study of Soil Types 449 Table 68 — Hanford Fine Sandy Loam, First Crop Milo B Planted, June 10, 1916. Harvested, November 20, 1916 Straw Grain Total dry matter A A. A No. Average Average Average Pot plants Weight weight Weight weight Weight weight Notes 14-., 8 10.75 10.75 14-2 8 10.95 10.95 14-3 8 8.84 10.18 8.84 10.18 15-1 5 5.25 5.25 15-2 4 4.62 4.62 15-3 2 3.92 4.60 3.92 4.60 16-1 7 7.36 7.36 16-2 2 2.18 2.18 16-3 4 2.74 4.09 2.74 4.09 19-1 3 3.73 3.73 19-2 8 4.79 4.79 19-3 8 9.60 6.04 9.60 6.04 20-1 8 8.14 8.14 20-2 8 3.23 3.23 20-3 8 3.22 4.86 3.22 4.86 22-1 6 4.74 4.74 22-2 5 3.01 3.01 22-3 7 3.19 3.64 3.19 3.64 23-1 8 5.68 5.68 23-2 5 7.72 7.72 23-3 8 6.93 6.78 6.93 6.78 24-1 3 3.16 3.16 24-2 6 5.64 5.64 24-3 6 3.26 4.02 3.26 4.02 25-1 4 3.07 3.07 25-2 3 2.34 2.34 25-3 8 4.34 3.25 4.34 3.25 450 University of California Publications in Agricultural Sciences [Vol. 3 Table 69 — Hanford Fine Sandy Loam, First Crop Millet Planted, June 10, 1916. Harvested: Nos. 15-25, September 20, 1916; No. 14, October 6, 1916 No. plants Straw A Grain Total dry matter A Average Weight weight Pot r Weight Average weight r Weight Average weight Notes 14-1 12 3.75 2.90 6.65 14-2 13 4.23 2.95 7.18 14-3 14 3.46 3.81 2.01 2.62 5.47 6.43 15-1 12 3.63 1.02 4.65 15-2 12 4.63 1.31 5.93 15-3 12 3.86 4.04 1.12 1.15 4.98 5.19 16-1 13 1.96 0.74 2.70 16-2 12 3.10 1.81 4.91 16-3 12 1.52 2.19 0.73 1.09 2.25 3.29 19-1 12 1.85 0.73 2.58 Seed immature 19-2 12 1.71 0.76 2.48 Poor. Lack of 19-3 12 2.00 1.85 0.69 0.73 2.69 2.58 drainage? 20-1 12 6.54 2.78 9.32 Possible error in 20-2 20-3 12 12 1.70 6.57 6.55 1.01 2.21 2.50 2.71 8.78 9.05 grain weight. Original shows 6 grams 22-1 12 2.04 0.65 2.69 22-2 12 2.32 0.68 3.00 22-3 12 4.44 2.93 1.90 1.08 6.34 4.01 23-1 12 6.12 1.21 7.33 23-2 12 6.13 2.14 8.27 23-3 12 6.01 6.08 1.97 1.78 7.99 7.86 24-1 12 4.18 1.50 5.69 24-2 12 2.80 0.91 3.70 24-3 11 4.89 3.96 2.08 1.50 6.98 5.46 25-1 12 2.06 0.77 2.83 25-2 12 2.01 0.51 2.52 25-3 12 4.31 2.79 2.15 1.14 6.46 3.94 1919J Pendleton: A Study of Soil Types 451 Table 70 — Hanford Fine Sandy Loam, First Crop Soy Beans Planted, June 10, 1916. Harvested, December 11, 1916 Straw Beans Total dry matter f ^ f ^ f A ^ No. Average Average Average Pot plants Weight weight Weight weight Weight weight Notes 14-1 6 16.69 16.69 Immature seed 14-2 6 16.28 16.28 Immature seed 14-3 6 11.89 14.95 0.44 0.15 12.33 15.10 Immature seed 15-1 6 14.08 0.23 14.31 Immature seed 15-2 6 5.17 5.17 Immature seed 15-3 6 6.53 8.59 0.08 6.53 8.67 Immature seed 16-1 6 12.63 0.32 12.95 Immature seed 16-2 6 14.60 14.60 Immature seed 16-3 6 16.60 14.61 0.11 16.60 14.72 Immature seed 19-1 6 12.84 12.84 Immature seed 19-2 6 11.68 11.68 Immature seed 19-3 6 16.03 13.52 16.03 13.52 Immature seed 20-1 6 8.77 8.77 Immature seed 20-2 6 16.33 16.33 Immature seed 20-3 6 14.27 13.13 14.27 13.13 Immature seed 22-1 6 20.28 20.28 Immature seed 22-2 6 19.44 19.44 Immature seed 22-3 6 15.60 18.44 15.60 18.44 Immature seed 23-1 6 21.42 21.42 No seed 23-2 6 20.75 ...... 20.75 No seed 23-3 6 20.68 20.95 20.68 20.95 Immature seed 24-1 6 17.37 17.37 Immature seed 24-2 6 21.24 21.24 Immature seed 24-3 6 13.70 17.43 13.70 17.43 Immature seed 25-1 6 5.53 . 5.53 Eained on; exclud- ed from average 25-2 6 17.85 17.85 No seed 25-3 6 21.58 19.71 21.58 19.71 Immature seed 452 University of California Publications in Agricultural Sciences [Vol. 3 Table 71 — Hanford Fine Sandy Loam, First Crop Cowpeas A Planted, June 10, 1916. Harvested, October 21, 1916 No. plants Straw- Beans A Total d f Weight ry matter Pot Average Weight weight r ^ Average Weight weight Average weight Notes 14-1 6 2.99 0.93 3.92 14-2 6 3.52 3.52 14-3 6 4.18 3.56 4.18 3.87 15-1 „ 15-2 15-3 -- 16-1 1 2.98 2.98 Immature seed 16-2 3 3.05 1.50 4.58 16-3 4 2.60 2.88 2.16 1.22 4.76 4.10 19-1 6 1.49 0.27 1.77 19-2 6 1.54 0.28 1.82 19-3 2 1.10 1.38 0.47 0.34 1.57 1.72 20-1 6 2.86 0.32 3.18 20-2 6 2.08 0.58 2.66 20-3 6 2.99 2.64 0.33 0.41 3.32 3.05 22-1 5 1.80 0.23 2.02 22-2 .. 22-3 2 1.96 1.88 0.39 0.31 2.35 2.19 23-1 .. 23-2 1 1.80 0.76 2.57 23-3 1.80 0.76 2.57 24-1 2 1.06 0.25 1.30 24-2 1 1.80 1.29 3.09 24-3 2 1.75 1.54 0.45 0.66 2.20 2.20 25-1 3 2.74 2.03 4.78 25-2 1 1.88 2.28 4.17 25-3 2 2.12 2.25 1.24 1.85 3.36 4.10 1919] Pendleton: A Study of Soil Types 453 Table 72 — Hanford Fine Sandy Loam, First Crop Cowpeas B Planted, June 10, 1916. Harvested, November 21, 1916 Straw Beans Total dry matter ' \ » ' * »' " > No. Average Average Average Pot plants Weight weight "Weight weight Weight weight Notes 14-1 6 3.94 3.94 14-2 6 5.93 5.92 14-3 6 3.32 4.39 3.32 4.39 15-1 6 7.24 7.24 15-2 6 5.34 5.34 15-3 6 4.61 5.74 4.61 5.74 16-1 6 5.90 5.90 16-2 6 5.82 5.82 16-3 6 3.65 5.12 3.65 5.12 19-1 6 3.34 3.34 19-2 6 3.38 3.38 19-3 6 3.87 3.53 3.87 3.53 1 died early 20-1 6 3.09 3.09 20-2 6 3.15 3.15 1 died early 20-3 6 2.80 3.01 ..,. 2.80 3.01 22-1 6 3.12 3.12 22-2 6 3.61 3.61 22-3 6 4.92 3.88 4.92 3.88 23-1 6 4.59 4.59 23-2 6 6.04 6.04 23-3 6 4.08 4.90 4.08 4.90 24-1 6 3.81 3.81 24-2 5 4.28 4.28 24-3 6 6.42 4.84 6.42 4.84 25-1 5 4.17 4.17 25-2 6 3.93 3.93 1 died early 25-3 6 4.86 4.32 4.86 4.32 Hanford fine sandy loam. Second crop. — Barley (twice), oats, wheat, bur clover (Medicago sp.), and Melilotus indica were the indi- cator crops used when the Hanford soils were planted the second time. In all cases a sufficient quantity of seed was used to insure the growth of more plants than would be raised to maturity. Later the plants in each pot were thinned to six in number, good specimens and well 454 University of California Publications in Agricultural Sciences [Vol. 3 spaced. The final number of plants varied, but was almost always six. An attempt was made to reduce at least partially the shading and exposure effects. The pots were periodically changed from position to position on the bench. The total dry weights produced on the several soils are interesting (tables 73-78, and fig. 33). The grains gave more uniform results in this crop than in the first. Soils nos. 14 and 23 show the best crops, and they are the ones that have the highest amounts of total nitrogen. The legumes selected must have been particularly well adapted to the growing conditions and the soils, because the growth was enormous. In the amount of dry matter produced the parallelism between the two legumes from soil to soil is close. It is noteworthy that soil no. 14, Wheat Bur Clover Oats "^Meli lotus 26 ^ arle ^ Fig.3£ Fig. 32. Graph showing the total dry matter produced by barley, wheat, oats, rye, bur clover, and Melilotus indica on the eight samples of San Joaquin sandy loam. First and only crop. which showed the highest total nitrogen and produced the most dry matter from the grains, gave the poorest crop of legumes. The notes taken during the growing period show that the relative appearances quite early and throughout the period of growth are usually a good index to the relative amounts of dry matter produced. This is so, even though the photographs of the mature plants do not show dif- ferences nearly as great in magnitude as do the dry weights. This type does not show any marked tendency for the several soils to approach a more uniform crop producing capacity through being kept under the same conditions. In fact, the second crop shows greater variations than the first. And this type does not show that these nine soils, mapped under a single type name, are closely similar to one another in crop producing power. 1919] Pendleton: A Study of Soil Types 455 Table 73 — Hanford Fine Sandy Loam, Second Crop Wheat (following millet) Planted, October 30, 1916. Harvested, June 21, 1917 Straw Grain Total dry matter , A . . A „ . A . r ^ f ~\ f ^ No. Average Average Average plants Weight weight Weight weight Weight weight Notes 3.55 14.30 2.10 7.30 10.26 6.45 4.03 21.30 14.30 1.30 4.65 1.50 6.35 3.66 1.10 1.30 3.90 4.96 Pot plants Weight 14-1 6 10.75 14-2 5 5.20 14-3 6 14.85 15-1 6 3.55 15-2 6 4.85 15-3 6 2.80 16-1 6 3.20 16-2 6 8.20 0.95 4.15 3.70 11.90 Eained on, exclud- ed from average 16-3 6 2.80 3.00 0.70 0.82 3.50 3.82 0.75 0.65 2.60 0.60 0.66 2.80 1.55 4.75 12.90 2.17 0.90 0.40 4.18 0.90 0.73 1.60 1.60 4.46 1.10 1.43 8.30 0.90 3.20 5.40 0.90 9.05 0.35 2.37 0.80 0.57 19-1 6 2.80 19-2 6 2.80 19-3 6 2.20 20-1 6 5.45 20-2 6 4.05 20-3 6 21.35 22-1 6 4.15 22-2 6 3.95 22-3 6 4.45 23-1 6 4.90 23-2 6 4.75 23-3 6 3.75 24-1 6 18.60 24-2 6 3.20 24-3 6 23.75 25-1 6 15.75 25-2 6 2.50 25-3 6 2.25 3.55 3.45 2.80 3.26 I 8.25 5.60 34.25 6.90 Eained on, exclud- 5.05 ed from average 4.35 5.35 4.92 6.50 6.35 4.85 5.90 26.90 Rained on, exclud- ed from average 4.10 Rained on, exclud- 29.15 4.10 ed from average Rained on, exclud- 24.80 ed from average 2.85 3.05 2.95 456 University of California Publications in Agricultural Sciences [Vol. 3 Table 74 — Hanford Fine Sandy Loam, Second Crop Oats (following milo A) Planted, November 22, 1916. Harvested, June 18, 1917 Straw Grain Total dry matter „ A . , A A „ t ^ r \ r "i No. Average Average Average weight Weight weight Weight weight Notes 2.90 6.70 1.85 5.25 3.47 2.40 2.38 5.65 5.86 Pot plants Weight 14-1 6 3.80 14-2 6 3.40 14-3 6 3.20 15-1 6 2.45 15-2 6 1.75 15-3 6 2.00 16-1 6 11.15 16-2 6 2.15 1.85 5.25 2.40 2.38 5.65 1.35 3.80 1.25 3.00 1.50 1.36 3.50 8.40 19.55 2.30 4.45 3.50 3.43 Eained on, exclud- ed from average Pot saturated with soluble salts, ex- cluded from av- erage 16-3 6 1.15 2.15 0.70 2.30 1.85 4.45 19-1 6 1.75 1.25 3.00 19-2 6 4.55 2.95 7.50 19-3 6 1.35 2.55 0.95 1.72 2.30 4.27 20-1 6 10.45 6.30 16.75 Eained on, exclud- ed from average 20-2 6 1.55 1.05 2.60 20-3 6 1.65 1.60 1.00 1.02 2.65 2.62 22-1 6 1.65 1.10 2.75 22-2 6 2.10 1.15 3.25 22-3 6 2.50 2.08 1.50 1.25 4.00 3.33 23-1 6 2.70 1.55 4.25 23-2 6 1.90 1.60 3.50 23-3 6 3.20 2.60 2.00 1.71 5.20 4.32 24-1 6 4.80 3.10 7.90 24-2 6 16.75 9.80 26.55 Rained on, exclud- ed from average 24-3 6 3.35 4.07 2.35 2.73 5.70 6.80 25-1 6 1.95 1.30 3.25 25-3 6 2.25 2.00 1*40 1.30 3.65 3.30 25-2 6 1.80 1.20 3.00 No. plants Straw Grain Total dry matter K A Pot r Weight Average weight r y r y Average Average Weight weight Weight weight 14-1 6 4.75 4.30 9.05 14-2 6 9.22 9.00 18.22 14-3 6 11.97 8.65 10.85 8.05 22.82 16.69 1919] Pendleton: A Study of Soil Types 457 Table 75 — Hanford Fine Sandy Loam, Second Crop Barley A (following cowpeas A) Planted, October 30, 1916. Harvested, May 20, 1917 Notes 15-1 6 15.47 15.30 30.77 Kained on, exclud- ed from average 3.29 4.39 4.12 3.70 6.42 2.55 4.01 1.71 3.56 1.80 1.91 2.70 2.25 1.98 2.90 2.80 3.44 7.45 2.85 2.07 3.53 4.10 2.73 2.78 3.35 4.23 6.24 4.20 3.93 2.54 9.75 3.90 3.57 3.05 1.75 4.22 Eained on, exclud- ed from average Pot broken, ex- cluded from av- erage 25-3 6 3.01 2.74 2.18 1.96 5.19 4.70 15-2 6 3.78 15-3 6 5.00 16-1 6 7.28 16-2 6 2.55 16-3 6 2.20 19-1 6 2.82 19-2 6 2.39 19-3 6 2.89 20-1 6 3.57 20-2 6 3.32 20-3 6 19.35 22-1 6 2.73 22-2 6 5.89 22-3 6 3.69 23-1 6 5.29 23-2 6 6.19 23-3 6 7.98 24-1 6 3.07 24-2 6 21.85 24-3 6 4.73 25-1 6 2.47 25-2 6 Lost 7.07 9.12 8.09 13.70 5.10 3.91 7.57 4.62 4.30 5.14 4.68 6.47 6.12 26.70 6.29 Eained on, exclud- ed from average 4.80 9.42 6.42 6.88 8.64 10.42 12.18 10.41 5.61 31.60 8.30 6.95 458 University of California Publications in Agricultural Sciences [Vol. 3 16-3 Table 76 — Hanford Fine Sandy Loam, Second Crop Barley B (following soy beans) Planted, January 31, 1917. Harvested, June 21, 1917 No. plants Straw Grain Total c r Weight Lry matter Pot r "\ Average Weight weight r Weight Average weight > Average weight 14-1 6 9.55 6.80 16.35 14-2. 6 6.05 5.40 11.45 14-3 6 3.80 6.47 2.10 4.76 5.90 11.23 15-1 6 3.50 2.80 6.30 15-2 6 3.20 1.70 4.90 15-3 6 4.05 3.58 2.60 2.36 6.65 5.95 16-1 6 3.10 1.45 4.55 16-2 6 9.20 8.20 17.40 Notes 7.35 19-1 6 3.05 19-2 6 2.65 19-3 6 2.15 20-1 6 3.35 20-2 6 4.20 20-3 6 2.55 22-1 6 2.05 22-2 6 2.90 22-3 6 3.15 23-1 6 3.10 23-2 6 3.10 23-3 6 3.40 24-1 6 3.10 24-2 6 10.10 24-3 3.05 3.10 2.62 3.36 2.70 3.20 2.65 4.50 0.80 2.20 1.85 2.60 3.20 2.15 1.75 2.35 2.25 2.05 2.95 2.75 1.45 5.80 2.35 1.45 11.85 3.85 4.85 4.00 1.61 2.65 2.12 2.58 1.90 5.95 7.40 4.70 3.80 5.25 5.40 5.15 6.05 6.15 3.70 15.90 5.40 4.55 4.23 6.02 4.82 Eained on, exclud- ed from average Eained on, exclud- ed from average Eained on, exclud- ed from average 4.55 25-1 25-2 25-3 3.35 3.10 4.70 3.72 2.90 1.85 4.60 3.12 6.25 4.95 9.30 6.83 1919] Pendleton: A Study of Soil Types 459 Table 77 — Hanford Fine Sandy Loam, Second Crop Melilotus indica (following cowpeas B) Planted, November 22, 1916. Harvested, June 21, 1917 No. plants Straw Unhulled seed A Total d Weight ry matter Pot r Weight Average weight r Weight Average weight Average weight Notes 14-1 6 17.00 15.80 32.80 14-3 6 13.25 16.45 29.70 14-3 6 4.40 15.12 3.10 16.12 7.50 31.25 Excluded from average 15-1 6 35.00 34.75 69.75 15-2 6 24.85 27.28 52.05 15-3 6 28.95 29.60 32.70 31.58 61.65 61.15 16-1 5 23.50 24.90 48.40 16-2 6 30.80 25.50 56.30 16-3 6 23.65 25.98 25.70 25.37 49.35 51.35 19-1 6 20.50 18.35 38.85 19-2 6 26.90 23.20 50.10 19-3 6 26.20 24.53 27.40 22.98 53.60 47.52 20-1 6 20.55 17.80 38.35 20-2 6 20.75 21.20 41.95 20-3 6 28.85 23.38 26.05 21.68 54.90 45.07 22-1 6 28.00 28.10 56.10 22-2 6 32.30 34.20 66.50 22-3 6 28.25 29.52 31.85 31.38 60.10 60.90 23-1 6 38.05 34.25 72.30 23-2 6 34.40 36.55 70.95 23-3 6 32.25 34.90 32.35 34.38 64.60 69.28 24-1 6 37.35 31.40 68.75 24-2 6 25.90 28.10 54.00 24-3 6 29.05 30.77 30.15 29.88 59.20 60.65 25-1 6 25.35 30.45 55.80 25-2 6 33.90 35.90 69.80 25-3 6 32.10 30.45 36.65 34.33 68.75 64.78 460 University of California Publications in Agricultural Sciences [Vol. 3 Table 78 — Hanford Fine Sandy Loam, Second Crop Bur Clover (following milo B) Planted, November 22, 1916. Harvested, June 25, 1917 No. plants Straw A Burs A Total dry r Weight matter Pot Weight Average weight r Weight Average weight Average weight 14-1 7 6.70 17.55 24.25 14-2 6 7.00 16.85 23.85 14-3 6 6.10 6.60 14.50 16.30 20.60 22.90 15-1 6 13.30 29.10 42.40 15-2 6 14.45 33.10 47.55 15-3 6 17.10 14.95 26.65 29.62 43.75 44.56 16-1 6 8.85 15.40 24.25 16-2 6 12.25 29.60 41.85 16-3 6 10.05 10.38 21.90 22.30 31.95 32.68 19-1 6 9.90 19.90 29.80 19-2 6 7.70 17.80 25.50 19-3 6 8.20 8.60 22.40 20.03 30.60 28.63 20-1 6 7.90 22.50 30.40 20-2 6 9.75 23.30 33.05 20-3 6 8.70 8.78 20.50 22.10 29.20 30.88 22-1 6 15.90 38.00 53.90 22-2 6 13.20 23.40 36.60 22-3 6 14.50 14.53 31.30 30.90 45.80 45.43 23-1 6 14.45 37.40 51.85 23-2 6 13.55 27.30 40.85 23-3 6 12.05 13.35 28.00 30.90 40.05 44.25 24-1 6 10.60 24.30 34.90 24-2 6 12.10 34.10 46.20 24-3 6 10.25 10.98 24.00 27.46 34.25 38.45 25-1 6 17.90 40.00 57.90 25-2 6 14.60 30.80 45.40 25-3 6 13.35 15.28 26.40 32.40 39.75 47.68 Notes San Joaquin sandy loam. — The samples of this type were the last to be weighed into pots and planted, because of the lack of available greenhouse space ; therefore the time allowed for the growing of but one crop, instead of two, on each pot of soil. The crops used were wheat, barley, rye, oats, bur clover (Medioago sp.), and Melilotns indioa. As was done for the other types, an excess of seed was planted. When the plants were well established, thinning reduced the number to six plants per pot. Since the specific gravity of this soil was high, because of the large amount of quartz and the small amount of organic matter in its com- position, six kilos of soil, instead of five, were weighed out into each pot. The samples of this type have the very annoying peculiarities of becoming very mushy if an excess of water be added, and of setting 1919] Pendleton: A Study of Soil Types 461 with a very hard surface on drjdng. This makes the soils hard to handle in greenhouse pot culture work. The variation in crop growth from soil to soil, as shown by the total dry matter produced (tables 79-84 and fig. 32), is rather marked. That the several samples do not show equal crop producing powers is very evident, though with regard to the several indicator crops the soils would frequently not maintain the same order. Soil no. 26 gave the poorest yields with all six crops. Except for wheat, the soils nos. 10, 11, and 12 gave low yields with both the grains and the legumes. It is interesting to note that wheat gave relatively high yields with a number of the soils, and wheat has probably been raised on these soils more than any other one crop. This series shows that, as far as the samples represent the type and the crops used represent crops as a whole, the soils mapped under a given type name are not closely similar in crop producing power under greenhouse conditions. Table 79 — San Joaquin Sandy Loam Rye Planted, November 22, 1916. Harvested, June 21, 1917 No. plants Sti raw Grain Total dry r Weight matter Pot Weight Average weight r Weight Average weight Average weight Not 10-1 6 1.70 0.30 2.00 10-2 6 2.30 0.35 2.65 10-3 6 2.05 2.02 0.65 0.43 2.70 2.45 11-1 6 3.15 0.70 3.85 11-2 6 2.25 0.70 2.95 11-3 4 3.20 2.87 0.70 0.70 3.90 3.57 12-1 6 1.65 0.45 2.10 12-2 6 2.45 0.85 3.30 12-3 6 2.40 2.17 0.65 0.65 3.05 2.82 13-1 6 4.20 1.25 5.45 13-2 6 4.30 0.80 5.10 13-3 6 3.75 4.08 1.60 1.22 5.35 5.30 17-1 6 7.55 1.60 9.15 Rained on 17-2 6 1.95 0.55 2.50 17-3 6 1.80 1.87 0.45 0.50 2.25 2.37 18-1 6 2.35 0.85 3.20 18-2 6 0.90 0.30 1.20 18-3 6 3.70 2.32 1.20 0.78 4.90 3.10 21-1 6 2.20 0.80 3.00 21-2 6 2.70 0.95 3.65 21-3 6 6.55 2.45 2.35 0.87 8.90 3.33 Rained on 26-1 6 1.50 0.60 2.10 . 26-2 6 2.55 0.75 3.30 26-3 6 2.50 2.18 0.70 0.68 3.20 2.87 462 University of California Publications in Agricultural Sciences [Vol. 3 65 60 .35 50 45 40 85 30 25 20 15 10 / / \ 1 V __L / / \ \ / \ \ \ T 1 1 / / / \ \ \ 1 1 / / / N ^\ 1 1 / / / / / / / / 1 / \ w \ ~~~~~^-' :s *-, t **X' "■•"^r.""^ marAMk - ?C ^"* '"•. *S Melilotus Bur Clover Barley B Barley A Oats Wheat 14 15 16 19 20 22 23 24 25 Soils Fig. 33. Graph showing the total dry matter produced by wheat, oats, barley (two series), bur clover, and Melilotus indica on the nine samples of Ilanford fine sandy loam. Second crop. 1919] Pendleton: A Study of Soil Types 463 Table 80 — San Joaquin Sandy Loam Barley Planted, October 30, 1916. Harvested, June 17, 1917 Straw Grain Total dry matter Pot No. plants r Weight Average weight r Weight Average weight r Weight Average weight Notes 10-1 6 2.93 0.92 3.85 10-2 6 1.87 0.81 2.68 10-3 6 1.47 2.09 0.85 0.86 2.32 2.95 11-1 6 1.91 0.66 2.57 11-2 6 2.02 1.28 3.30 11-3 6 2.97 2.30 0.90 0.95 3.87 3.25 12-1 6 10.27 4.95 15.22 Eained on; exclud- 12-2 6 3.60 1.32 4.92 ed from average 12-3 6 3.49 3.54 0.43 0.87 3.92 4.42 13-1 6 2.14 1.46 3.60 13-2 6 3.19 1.78 4.97 13-3 6 3.28 2.87 1.77 1.67 5.05 4.53 17-1 6 3.89 2.17 6.06 17-2 6 3.74 1.80 5.54 17-3 6 2.44 3.35 0.80 1.59 3.24 4.95 18-1 6 4.65 1.93 6.58 18-2 6 3.74 1.94 5.68 18-3 6 5.61 4.66 2.34 2.07 7.95 6.74 21-1 6 2.05 1.53 3.58 21-2 6 2.10 1.80 3.90 21-3 6 3.81 2.65 2.33 1.88 6.14 4.54 26-1 6 1.12 0.63 1.75 26-2 6 1.08 0.41 1.49 26-3 6 1.20 1.13 0.70 0.58 1.90 1.71 464 University of California Publications in Agricultural Sciences [Vol. 3 Table 81 — San Joaquin Sandy Loam Wheat Planted, October 30, 1916. Harvested, June 21, 1917 Straw Grain Total dry matter Pot No. plants Weight Average weight f Weight *> Average weight r Weight Average weight Not 10-1 6 3.59 0.85 4.80 10-2 6 3.45 0.45 3.90 10-3 6 6.35 4.58 0.75 0.68 7.10 5.26 11-1 6 5.60 1.15 6.75 11-2 6 2.75 0.60 3.35 11-3 6 3.45 3.93 0.70 0.81 4.15 4.75 12-1 6 6.85 2.00 8.85 12-2 6 7.50 1.35 8.85 12-3 6 4.45 6.27 1.35 1.56 5.80 7.83 13-1 6 3.90 0.85 4.75 13-2 6 3.25 0.45 3.70 13-2 6 3.95 3.70 0.75 0.68 4.70 4.38 17-1 6 2.70 0.25 2.95 17-2 6 1.20 0.45 1.65 17-3 6 2.75 2.21 none 0.23 2.75 2.45 18-1 6 5.90 1.50 7.40 18-2 6 7.90 2.40 10.30 Rained on 18-3 6 5.00 5.45 1.00 1.25 6.00 6.70 21-1 6 3.10 1.05 4.15 21-2 5 4.30 0.75 5.05 21-3 6 8.40 3.70 2.45 0.90 10.85 4.60 Rained on 26-1 6 2.35 0.55 2.90 26-2 6 0.40 none 0.40 Rained on 26-3 6 2.60 2.47 0.35 0.45 2.95 2.92 1919] Pendleton: A Study of Soil Types 465 Table 82 — San Joaquin Sandy Loam Oats Planted, November 22, 1916. Harvested, June 17, 1917 Straw Grain Total dry matter Pot No. plants r Weight Average weight r Weight Average weight Weight Average weight 10-1 6 2.25 0.90 3.15 10-2 6 3.65 1.90 5.55 10-3 6 1.70 2.53 0.50 1.10 2.20 3.63 11-1 6 2.25 1.25 3.50 11-2 6 1.75 0.95 2.70 11-3 6 2.10 2.03 1.00 1.07 3.10 3.10 12-1 6 1.70 0.90 2.60 12-2 6 2.40 1.00 3.40 12-3 6 2.35 2.15 1.05 0.98 3.40 3.13 13-1 6 2.25 1.20 3.45 13-2 6 2.40 1.10 3.50 13-3 6 2.70 2.45 1.70 1.33 4.40 3.78 17-1 6 0.80 0.55 1.35 17-2 6 1.50 0.90 2.40 17-3 6 1.25 1.90 0.70 0.72 1.95 1.90 18-1 6 1.70 1.00 2.70 18-2 6 1.15 0.60 1.75 18-3 6 1.10 1.32 0.50 0.70 1.60 2.02 21-1 6 1.85 0.95 2.80 21-2 6 2.35 1.05 3.40 21-3 6 1.00 1.73 0.55 0.85 1.55 2.58 26-1 6 1.55 0.60 2.15 26-2 6 1.35 0.80 2.15 26-3 6 1.65 1.52 0.70 0.70 2.35 2.22 Notes 466 University of California Publications in Agricultural Sciences [Vol. 3 Table 83 — San Joaquin Sandy Loam Bur Clover Planted, November 22, 1916. Harvested, June 17, 1917 Straw Seed in burs Total dry matter Pot No. plants Weight Average weight r Weight Average weight r Weight Average weight Notes 10-1 6 0.50 0.95 1.45 10-2 6 1.50 1.65 3.15 10-3 6 0.50 0.83 1.75 1.45 2.25 2.28 11-1 6 0.90 2.00 2.90 11-2 6 0.25 1.00 1.25 11-3 6 0.30 0.48 1.10 1.37 1.40 1.85 12-1 6 0.90 3.00 3.90 . 12-2 6 2.15 5.30 7.45 12-3 6 1.50 1.52 1.90 3.40 3.40 4.92 13-1 6 1.55 3.45 5.00 13-2 6 0.75 2.80 3.55 13-3 6 4.35 1.15 5.70 3.12 9.05 4.27 Excluded from av- erage 17-1 6 0.70 2.05 2.75 17-2 6 2.35 3.85 • 6.20 Excluded from av- erage 17-3 6 0.90 0.80 1.70 1.87 2.60 2.67 18-1 6 1.20 3.40 4.60 18-2 6 3.25 6.65 9.90 Excluded from av- erage 18-3 6 1.80 1.50 4.85 4.12 6.65 5.62 21-1 6 3.35 3.70 7.05 21-2 6 2.00 3.90 5.90 21-3 6 1.75 2.37 5.15 4.25 6.90 6.62 26-1 6 0.60 1.45 2.05 26-2 6 1.20 2.75 3.95 26-3 6 0.40 0.73 1.30 1.83 1.70 2.56 1919] Pendleton: A Study of Soil Types 467 Table 84 — San Joaquin Sandy Loam Melilotus indica Planted, November 22, 1916. Harvested, June 21, 1917. Notes No. plants Sti A •aw Unhull ed seed A Total dry Weight matter Pot r Weight Average weight r Weight Average weight Average weight 10-1 6 1.20 1.20 2.40 10-2 6 1.03 0.92 1.95 10-3 6 1.30 1.18 1.65 1.26 2.95 2.44 11-1 6 1.05 0.85 1.90 11-2 6 0.50 0.35 0.85 11-3 6 1.00 0.85 0.80 0.67 1.80 1.52 12-1 6 1.07 2.05 3.12 12-2 6 1.70 2.45 4.15 12-3 6 1.20 1.33 1.40 1.96 2.60 3.29 13-1 6 3.05 3.70 6.75 13-2 6 3.10 3.95 7.05 13-3 6 3.50 3.22 4.45 4.03 7.95 7.25 17-1 6 3.05 4.05 7.10 17-2 6 2.25 3.55 5.80 17-3 6 2.85 2.72 3.20 3.60 6.05 6.32 18-1 6 3.25 3.90 7.15 18-2 6 2.05 2.65 4.70 18-3 6 2.85 2.42 3.95 3.50 6.80 6.22 21-1 6 2.50 3.40 5.90 21-2 6 2.65 3.95 6.60 21-3 6 3.45 2.87 3.30 3.55 6.75 6.42 26-1 6 1.10 0.85 1.95 26-2 6 0.95 0.85 1.80 26-3 6 1.30 1.12 1.05 0.92 2.35 2.04 GENERAL DISCUSSION The limited time available for this study made it impossible to make all the determinations upon each of the several horizons of all the soils collected for this study. It was believed, however, that the additional data were not re- quired, since that already at hand seemed to give ample evidence upon which to base conclusions. Therefore, in many cases determinations were run on the surface horizon only. This makes some of the tables appear incomplete. 468 University of California Publications in Agricultural Sciences [Vol. 3 On the basis of the preceding results and discussions some general treatment is possible, as well as a more or less critical discussion of the methods of soil surveying pursued by the Bureau of Soils. The types and the localities of collection of the soils studied were as follows : Diablo clay adobe: Thalheim (17) San Juan Capistrano (1) Madera (18) Los Angeles (2) Merced (21) Calabasas (5) Del Mar (26) Danville (6) Kan ford fine sandy loam: Altamont clay loam Elk Grove (14) Walnut (3) Acampo (15) San Fernando Valley (4) Woodbridge (16) Mission San Jose (7) Waterford (19) Sa?i Joaquin sandy loam: Snelling (20) North Sacramento (10) Basset (22) Lincoln (11) Anaheim (23) Wheatland (12) Los Angeles (24) Elk Grove (13) Van Nuys (25) Note. — Figures following localities designate sample numbers. Comparisons of Physical Data The mechanical analyses of the soils were carried out with both the Hilgard elutriator and the Bnrean of Soils centrifuge methods. The tedious nature of the elutriator method has been emphasized else- where. The results by this method show that the soils of each type as a whole are somewhat similar, though no two are identical and some samples of a type are widely divergent from the rest. The Bureau of Soils method appears to give a sharper and more satisfac- tory separation into classes than does the elutriator method. This is to be expected since the separates represent greater ranges of particle sizes. As a check on the texture of the samples collected, it shows that some of the soils are not true to name, therefore that all soils mapped under a given type name are not closely similar to one another. Of course, this is the belief of many soil surveyors, but it seems strange that in the present work, where there was the attempt to select soils representative of the class and type chosen for study, that such diver- gences developed. It is an interesting commentary on the personal equation of the field worker, in this case of the writer, who collected the samples. 1919 j Pendleton: A Study of Soil Types 469 With regard to the methods of mechanical analysis, one should not overlook Mohr's work on The Mechanical Analysis of Soils of Java, 30 which gives an excellent discussion of the relative merits of the better known systems of mechanical analysis. He describes a modified cen- trifuge method preferred by him. Under a discussion of the physical constants of soils, Free 31 dis- cusses the value of mechanical analysis as a soil constant, and shows that there are three serious errors in the determination, all of which impress themselves upon one making and using such analyses. They are: "(1) disunity of expression; (2) failure to express conditions within the limits of individual groups; and (3) failure to take account of variations in the shapes of the particles." Yet he empha- sizes, and rightly so, i l that mechanical analysis is by no means useless nor to be belittled as a means of soil investigation." 32 Moisture equivalents. — This determination showed quite distinct averages for the types, though there was considerable variation within each of the types. Eliminating those samples shown to be non-typical according to the mechanical analysis, the variation within the type is reduced considerably. Yet it cannot be said that as regards this con- stant that all soils mapped under a given type name, or even those soils under a given type name which the mechanical analysis has shown to be true to name, have closely similar moisture equivalents. Briggs and McLane 33 express the belief that ultimately moisture equivalent determinations will replace mechanical analysis in the classification of soils, because the determination is simple and the result can be expressed as a single constant. Hygroscopic coefficient. — The two heavy types show averages dis- tinct from those of the two light types, but the wide and erratic varia- tion within the type, together with the nearly universal failure of Briggs and Shantz's formula 34 to convert these values into values even approximating those of the moisture equivalent, leads one to doubt the accuracy of these figures of the hygroscopic coefficient. It is because of the ease of determining the moisture equivalent, and because of the difficulties involved in correctly carrying out the hygro- scopic coefficient, that the doubt is cast upon the latter determination. so Bull. Dept. of Agr., Indes Neerland, 1910, no. 41, pp. 33. 3i Free, E. E., Studies in Soil Physics, Plant World, vol. 14 (1912), nos. 2, 5, 7, 8. 32 ibid., p. 29. 33 Proc. Amer. Soc. Agron., vol. 2 (1910), pp. 138-47. 34 U. S. Bur. PI. Ind., Bull. 230 (1912), p. 72. 470 University of California Publications in Agricultural Sciences [Vol. 3 Comparison of Chemical Data The total nitrogen content of the samples of each type varies within somewhat wide limits. The average amounts for the several types are distinct, though the variations are such that some of the quantities of one type overlap those of another type. It is believed that for the types selected the field differentiations do indicate dif- ferences. Eegarding the humus content of the four types under considera- tion, the results are somewhat different. The average amounts of humus are almost alike in three of the four types, while the nitrogen- poor San Joaquin soil has an average of about half that of the others. Within the type the soils may be very nearly alike in the humus con- tent, as is the case in two of the types, or may be widely variable, as in the Hanford fine sandy loam. It should be noted that the amount of humus as shown by the method used, is not indicated by the inten- sity of the color either of the soil or of the resulting extract. This confirms the findings of Gortner, which are cited elsewhere. There was quite a wide range shown in the results of the deter- mination of the loss on ignition. The Diablo and Altamont soils, be- cause of the heavier textures and the relatively large amounts of com- bined water, and of considerable amounts of CaC0 3 in at least one case, gave high losses on ignition. The averages were close, 6.8% for the Diablo, and 6.7% for the Altamont. The Hanford soils were lower, though with a wider range. Soil no. 14, with 6.9% loss on igni- tion, shows almost double that of any other soil in the type. The San Joaquin soils, with an average of 2.6%, show the lowest average loss on ignition. The smaller amounts of organic matter in these soils is one reason for the smaller loss. The two heavier types have averages close together, and the lighter types have averages not far apart, but because of the wide variations within each type, the results of the determination of the loss on ignition certainly do not show that all soils classified in one type are closely similar. Hall and Russell, in their discussion of the soils of southeastern England, 35 consider of value the ratio of Q-. — — : A — but apply- % loss on ignition, ing this ratio to the California soils under consideration does not seem to give any relations of value. The Diablo ratio varies from 0.0136 to 0.0158, the Altamont from 0.0141 to 0.0204, the San Joaquin from 0.0144 to 0.0232, and the Hanford from 0.011 to 0.0172. 85 Jour. Agr. Sci., vol. 4 (11)11), pp. 182-223. 1919] Pendleton: A Study of Soil Types 471 The calcium (as CaO) content of the soils is interesting especially because of the variability. The Altamont samples show the greatest variation, for the largest quantity of CaO is about seven times the smallest. The San Joaquin samples are second, with the largest over six times the smallest. The Diablo samples are third, with the largest over five times the smallest, while the Hanford soils show the least variation, the largest being less than twice the smallest. There are quite marked differences between the averages of the Diablo, Alta- mont, and Hanford soils (the San Joaquin samples are intermediate), but the wide variations within the types greatly minimize any sig- nificance the averages might have. Hence it is not possible to state that one or another type, as represented by these samples, is charac- terized by high, low, or moderate amounts of calcium. As the analyses of the samples for calcium failed to point out any striking characteristics, unless it be that of variability, so it is with magnesium. Magnesium (as MgO) is variable within each of the four types. The largest quantity is about three times the smallest in the Diablo, San Joaquin, and Hanford types, while in the Altamont the largest is twenty-seven times the smallest. Considering the Hanford and San Joaquin, or the Diablo and San Joaquin, it is seen that the curves do not overlap, while the Diablo and Altamont, or the Diablo and Hanford curves do. The averages of the four types are distinct, except between the Hanford and Diablo, which are quite close. But, here again, because of the more or less wide range of values within each of the types, the averages are of little significance. The lime- magnesia ratio is very variable in these soils. Comparing the calcium and magnesium curves for the several soils gives a good idea of the relations. The Diablo curves are quite similar except for soil no. 6, which shows 3% MgO and 0.5% CaO. In the Altamont soils the curves are somewhat similar in direction, though the ratios differ widely. In the Hanford and San Joaquin types the ratios of CaO and MgO are also far from constant, yet it is readily seen from the graphs that the amount of magnesium varies more or less directly with the amount of calcium. Respecting the total phosphorus (as P 2 5 ), if the San Joaquin and Hanford samples alone be considered, there would be no doubt as to the significance of the field separation, the variations within the type notwithstanding. But when the other two types are considered, the case is not so good in favor of the field classification. The Diablo soils show considerable variation in the amount of P r ,0 2 , while the three 472 University of California Publications in Agricultural Sciences [Vol. 3 Altamont samples show much variation. Therefore with reference to the amount of phosphorus, and the types studied, the separation into types may or may not be of significance. If the results of the potassium (K 2 0) determinations are com- pared, it is very evident that but one conclusion can be drawn, and that is that the variations in the amount of potassium within each type are great enough so that any differences between the averages of the several types have no significance whatsoever. Therefore, with regard to total potassium the field separation of soils as represented by these twenty-four samples of four types means nothing. Comparison of Bacteriological Data The wealth of the data obtained from over nine hundred bacteri- ological tumbler cultures is hardly of sufficient significance to com- pensate for the effort involved. There is one outstanding conclusion from all this work, namely, the lack of any very definite, distinct, and constant bacteriological activity of the samples of one type that is not to a considerable extent shared by the samples of the other types. There are tendencies in certain types with regard to bacteriological activity which show that some of the types as a whole are more or less distinct from one or more of the others. Ammonification. — The amount of ammonia produced from dried blood varies to a great extent. The Altamont samples gave between 10 and 33 mg. nitrogen as ammonia; the Diablo samples gave between 7 and 26 mg., and the Hanford samples gave between 35 and 72 mg. The Altamont and Diablo types are thus seen to be about alike in their low ammonifying power, as compared with the higher ability of the San Joaquin types and still greater ability of the Hanford types. And since there are somewhat greater variations between the types than between the samples of a given type, the ammonifying power may be significant. Nitrogen fixation. — The two heavy types, Diablo clay adobe and Altamont clay loam, show no characteristic differences, while the two lighter types show considerable differences. As a whole the types are different one from another, yet the variations within the type are sufficient to prevent any statement that the rate of nitrogen fixation is a function of the type as determined in the field, or vice versa. Nitrification. — The nitrification data are the most puzzling. The figures are extremely variable within a given type ; the erratic way 1919] Pendleton: A Study of Soil Types 473 in which the Hanford samples behave is not paralleled by any other type. There are certain ways in which the types are distinct : The nitrification of the soil's own nitrogen as compared with the soil's action upon added nitrogen is in some degree separate for each type. The San Joaquin samples nitrified their own nitrogen to a greater degree than they did the nitrogen added to the soil. The relative nitrification of the several nitrogenous materials (dried blood, cottonseed meal, ammonium sulfate) is in some measure distinct for the several types. The Diablo, Altamont, and San Joaquin types show ammonium sulphate to be nitrified the best, cottonseed meal less, and dried blood still less. The Hanford samples show cottonseed meal to give the highest percentage of nitrates, with dried blood less, and ammonium sulfate still less. When any one soil is compared through the three sets of deter- minations there are no apparent similarities. The Hanford type shows the greatest bacterial activity, while the San Joaquin shows less, with the heavier types showing sometimes greater activity and sometimes less than that of the San Joaquin. Work in Other States In connection with the original chemical work reported in this paper, there should be mentioned the large amount of work done in a number of states on the analysis of the types of soils as mapped by the Bureau of Soils. Apparently, these analyses have been made without any question as to the validity of the. existing subdivisions into types. The various analyses have been reported with some com- ment, but that which does appear usually deals with the "adequacy" or " inadequac3 T " of the plant food present. Blair and Jennings 36 present a large amount of data on chemical composition, some of which on rearrangement show interesting relationships (table 85). From the data the four series of soils with the largest number of analyses were selected (see following table). Under each series there are from 2 to 4 soil tj^pes, and from 2 to 6 analyses under each type. The averages from each type are tabulated, also the averages of all the types within the series. This is both for the strong acid extraction and the fusion methods of analysis for significant plant food elements. There are no doubts but that each series of soils shows characteristic chemical peculiarities, peculiarities which are to a great extent con- 36 The Mechanical and Chemical Composition of the Soils of the Sussex Area, New Jersey, Geol. Surv. N. J., Bull. 10, 1910. 474 University of California Publications in Agricultural Sciences [Vol.3 oSuBueqQ : : ° _ © jajsaonoio j : t- — ~\ .I3A0(J i : t> co fr- ^saqo^nQ; • : co 1- — CC o co I— to CO >o rH rH O! tO OS >o lO rH -M i—. CO CO OS CO CO — C to o ^ O O n SO Nri O so rH t^ CO r-i O i-i lO H^ rH X IO O lO M © oo co co rH to lO os : co HH »o to to M l> (M © LO -hh co os co : cm T* OS l~ CO LO co lO © rH «-! H H< o OS O rH : o to # o rH OS CO rH ' ^>> fl rH T3 9 rH >>fl OS l~ O rH OS L^ CO OS ,— | o Ol rH rH IC O OS ~ o o -H cq Tt< 02~ QO •? a CM LO CO CO 00 O LO CO LO rH CO H< © CD CM rH O © CO CO* H* CO LO LO tH L- o o • CO L^ CD OS LO © L- O rH CO* CO* LO LO rH 00 CO H< CD LO O CM O CM CO O OS HH CO CM CO CM L— ri N lO » ri ^ CO L- t- CT t> tH H (M M N H CO »o rH CD 00 b- CO © rH rH rH CO O OS LO OS 00 CO CM H lO W ^ H r-1 CM* rH CO © t- CO © LO t^OLO ©ajhlOWHHNah^M CDOrHOrHlOOCOOOOOO to lO N (O CO IO O0 O rH O CO o t- CM o to ^ co t> O 00 lO CO rH CD t- OS rH LO © CO © rH lO CO CM o co >o CM rH O CM 00 CO CO lO >0 00 CD rH tJJ t- OS rH rH CM* tO TtH tH HH CD © CO rH lO H^ CO rH rH CM* © _ O CD w2, i- HH I— CO t^ CO o to OS CO CO co to CD © r-i © © HH I- rH © © © rH HH CO* rH _ -.^-s CM »0 1- 1- O »0 CO H< gill) 1.^ CD rH LO © rH CO rH O OO CO CO rH C^ ^ O O CO O H Cl © OS 1-; rH © © CM j-Sx) o co' to* ^ " & oo r o co >o >o oo ci i: co cc oo x -t i? o « © co s 00 O CM O O CD © O OS rH © O CD ci ' co h* ' i- oo CO CO r-i CO O CM HH CO CM' rH CO t- l- fc«- 00 rH O0 CD * 9, o o ts ^ h cyj q -3 ft o g % k 1919] Pendleton: A Study of Soil Types 475 stant throughout the several representatives of the type. In some cases, the differences or similarities are more clearly seen in the total analyses, and in other cases, they appear in the acid analyses and not in the fusion analyses. Within any series the variations between analyses of any one type are about the same as the variations from type to type. There are many other papers 37 which provide material for similar comparisons. A paper by Van Dyne and Ashton 38 reports chemical analyses for lime, phosphoric acid, potash, and nitrogen on the samples collected in the course of the survey of Stevens County, Washington. Though sometimes there is a much greater range within a type than between types, in a general way the analyses for any one type agree quite well. As a whole the chemical analyses seem to show that the field criteria are also a basis for grouping soils into certain chemical groups. It should be mentioned that the work of Blair and Jennings, also that of Van Dyne and Ashton, deals with individual areas, and not with samples from several scattered areas. The work of Fraps and Williams, and the original work here reported represent scattered areas. The Greenhouse Cultures By far the most interesting results were obtained in the pot culture work. It is realized that there are variations in the physical nature of the samples of a given type, yet since these samples were collected with considerable care by one familiar with field classifications, the samples so selected should be fairly representative of the type. It is probable that if all the soils in each of the types used were exactly the same in texture, i.e., if the mechanical analysis showed the same results for the several soils, the crops produced on the several soils of a type would be less divergent in appearance or weight. Yet it is not at all likely that the crops would be the same. Pot cultures pre- sume that the conditions in all the pots can be kept uniform, but this is obviously impossible. Greenhouse work is subject to many interfer- ing factors. Nevertheless, the results are believed to be significant, 37 Williams, and others, Eeport on the Piedmont Soils, North Carolina Dept. Agr., Bull. 206, 1915. Fraps, G. S., Composition of the Soils of South Texas, Texas Agr. Exp. Sta., Bull. 161, 1913; Composition of the Soils of the Texas Panhandle, ibid., Bull. 173, 1915. 38 Van Dyne and Ashton, Soil Survey of Stevens County, Washington, Field Operations, U. S. Bur. Soils, 1913, pp. 2165-2295. 476 University of California Publications in Agricultural Sciences [Vol.3 despite the large correction that the consideration of the probable error might introduce. The differences in the crop producing power of the soils are very marked in the Diablo clay adobe, where the second crop, as well as the first, shows evident variations in the ability to support a crop. In the Altamont clay loam the second crop almost loses the variations seen in the first crop from pot to pot. The samples of both types seem to show one thing in common — the approach of the several sam- ples toward a uniform ability to produce crops, as the soils are kept for longer periods under the same conditions. The Hanford soils did not show, with the several crops, the parallelism in the fertility from crop to crop as did the Diablo and Altamont soils. Some soils pro- duced good crops of grain and poorer crops of legumes, others did the opposite. The low nitrogen content in this type seemed to be a limit- ing factor. This would account for the variation between the grain and the leguminous crops. Also, the presence, or absence of Bacillus radicuola inoculation in this connection might greatly affect the total crop produced. There does not seem to be much doubt but that the soils of the several types compared in this way are not the same, though they are in certain respects similar. The Place of Soil Classification. — With all these evidences that the soils within the several types are not closely similar, though they are classified the same by the Bureau of Soils, what conclusion is one to reach as to the value of such a classification ? If it were true that there were no appeal from the findings of such laboratory and greenhouse W^v W&H %il .* : : ; f Diablo Clay Adobe — First Crop Pots of same and different representatives of a given soil type compared. Fig. 1. Bnr clover. Left to right — Soil 5, pot 1; soil 5, pot 2; soil 5, pot 3. m Diablo Clay Adobe — First Crop Pots of same and different representatives of a given soil type compared. Fig. 2. Bur clover. Left to right— Soil 6, pot lj soil 6, pot 2; soil 6, pot 3. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [ PENDLETON ] PLATE 47 Diablo Clay Adobe — First Crop Pots of same and different representatives of a given soil type compared. Bur clover. Left to right — Soil 1, pot 1; soil 2, pot 2; soil 5, pot 2; soil 6, pot 1. UNIV. CALIF. PUBL. AGR. SCI. VOL, 3 [PENDLETON] PLATE 48 t Diablo Clay Adobe — Second Crop Pots of same and different representatives of a given soil type compared. Dwarf milo («) following oats. Left to right — Soil 1, pot 2; soil 1, Fig. 1. pot 3; soil 2, pot 1 ; soil 2, pot 3; soil 5 pot 3. pot 1 ; soil 5, pot 3; soil 6, pot 2; soil 6, • Diablo Clay Adobe — Second Crop Pots of same and different representatives of a given soil type compared. Fig. 2. Dwarf milo (b) following oats and bur clover. Left to right — Soil 1, pot 1; soil 1, pot 3; soil 2, pot 1; soil 2, pot 3; soil pot 1 ; soil 6, pot 3. 5, pot 1; soil 5, pot 3; soil 6, UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [ PENDLETON 1 PLATE 49 Diablo Clay Adobe — Second Crop Pots of same and different representatives of a given soil type compared. Fig. 1. Cowpeas, following wheat. Left to right — Soil 1, pot 1 ; soil 1, pot 2; soil 2 pot 1 ; soil 2, pot 2; soil 5, pot 1 ; soil 5, pot 2; soil (i, pot 2; soil . :i Haxford Fine Sandy Loam — First Crop Pots of same and different representatives of a given soil type compared. Fig. 2. Dwarf milo B. Left to right— Soil 14, pot 1; soil 14, pot 2; soil 14, pot 3; soil 22, pot 1; soil 22, pot 2; soil 22, pot 3; soil 23, pot 1; soil 23, pot 2; soil 23, pot 3. i UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [PENDLETON] PLATE 55 Haxford Fixe Sandy Loam — First (jrop Pots of same and different representatives of a given soil type compared. Fig. 1. Soy beans. Left to right — Soil 14, pot 1; soil 15, pot 1; soil 16, pot 2; soil L9, pot 2; soil 20, pot 3: soil 22, pot 1; soil 23, pot 3; soil 24, pot 1; soil 2.", pot 3. Haxford Fine Sandy. Loam — First Crop Pots of same and different representatives of a given soil type compared. Fig. 2. Soy beans. Left to right— Soil 14, pot 1; soil 14, pot 2; soil 14, pot 3; soil 16, pot 1; soil 16, pot 2; soil 16, pot 3; soil 23, pot 1; soil 23, pot 2; soil 23, pot 3. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [ PENDLETON ] PLATE 56 Haxford Fine Sandy Loam — First Crop Pots of same and different representatives of a given soil type compared. Fig. 1. Cowpeas B. Left to right— Soil 14, pot 1; soil 14, pot 2; soil 14, pot 3; soil 22, pot 1 ; soil 22, pot 2; soil 22, pot 3; soil 23, pot 1; soil 23, pot 2; soil 2:;, pot :;. *; Mi ' ££& A I A ii^A A A* A Hanford Fine Sandy Loam — First Crop Pots of same and different representatives of a given soil type compared. Fig. 2. Cowpeas B. Left to right — Soil 14, pot 3; soil 15, pot 2; soil 16, pot 2; soil 19, pot 2; soil 20, pot 2; soil 22, pot 2; soil 23, pot 2; soil 24, pot 1; soil 25, pot 3. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [ PENDLETON ] PLATE 57 1 i / 'J^ tf ?*iLBgMi g^agfe i £gi ^ "f £** * gMflpfc &t$m \ Hanford Fixe Sandy Loam — Second Crop Pots of same and different representatives of a given soil type compared. Fig. 1. Barley, following soy beans. Left to right — Soil 14, pot 2; soil 15, pot I ; soil 16, pot 3; soil 19, pot 3; soil 20, pot 1; soil 22, pot 2; soil 23, pot 3; soil 24, pot •"> : soil 2-"), pot 1. Hanford Fine Sandy Loam — Second Crop Pots of same and different representatives of a given soil type compared. Fig. 2. Barley, following soy beans. Left to right — Soil 14, pot 1; soil 14, pot 2; soil 14, pot 3; soil 19, pot 1; soil 19, pot 2; soil 19, pot 2; soil 19, pot 3; soil 23, pot 1; soil 23, pot 2; soil 23, pot 3. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [PENDLETON] PLATE 58 |M | t J ] If I V:' ;«l» v !ii Es&sJLJL'U MM ?-<*izm? i**&m&>m«T^a& ! '* v&n "•itfafiK^vss. IIaxford Fine Sandy Loam — Second Crop Pots of same and different representatives of a given soil type compared. Wheat, following millet. Left to right — Soil 14, pot 1; soil 15, pot 1; soil 16, pot 1; soil 19, pot 3; soil 20, pot 1; soil 22, pot 1; soil 23, pot 1; soil 24, pot 1; soil 25, pot 3. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [PENDLETON] PLATE 59 . Hanford Fine Sandy Loam — Second Crop Pots of same ami different representatives of a given soil type compared. Wheat, folio-wing millet. Left to right — Soil 16, pot 1 ; soil 16, pot 2 ; soil 16, pot 3; soil 22, pot 1 ; soil 22, pot 2; soil 22, pot 3; soil 24, pot 1; soil 24, pot 2; soil 24, pot 3. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [PENDLETON] PLATE 60 Hanford Fixe Sandy Loam — Second Crop Pots of same and different representatives of a given soil type compared. Fig. 1. Barley, following cowpeas. Left to right — Soil 14, pot 2; soil 15, pot ::; soil 16, pot 2; soil ]9, pot 2; soil 20, pot 1; soil 22, pot 3; soil 23, pot 3; soil 24, pot :'» ; soil 2.1, pot 1. '. Haxford Fine Sandy Loam — Second Chop Pots of same and different representatives of a given soil type compared. Fig. 2. Barley, following cowpeas. Left to right — Soil 19, pot 1; soil ]9, pot 2; soil j 9, pot 3; soil 20, pot 1; soil 20, pot 2; soil 20, pot 3; soil 23, pot 1; soil 23, pot 2 ; soil 23, pot 3. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [PENDLETON] PLATE 61 Hanford Fine Sandy Loam — Second Crop Pots of same and different representatives of a given soil type compared. Fig. 1. Oats, following milo. Left to right — Soil 14, pot 3; soil 15, pot 2; soil 16, pot 2; soil 19, pot 1; soil 20, pot 2; soil 22, pot 1; soil 23, pot 3; soil 24, pot 1 ; soil 25, pot 1. i **$* / " ;' .-^ " ' 'f '"BUiiiT ' ' i 1 """^ £ 1 j 1 1 ! ^> i | ! ! r ■ i" tej « — — — -^ = ■ - — ■; ■ _ Hanford Fine Sandy Loam — Second Crop Pots of same and different representatives of a given soil type compared. Fig. 2. Oats, following milo. Left to right — Soil 14, pot 1 ; soil 14, pot 2 ; soil 14, pot 3; soil 15, pot 1; soil 15, pot 2; soil 15, pot 3; soil 24, pot 1; soil 24, pot 2; soil 24, pot 3. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [ PENDLETON ] PLATE 62 Hanford Fine Sandy Loam — Second Crop Pots of same and different representatives of a given soil type compared. Melilotus indica, following eowpeas. Left to right — Soil 14, Pot 1; Soil 15, Pot 3; Soil 16, Pot 2; Soil 19, Pot 2; Soil 20, Pot 1. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [PENDLETON] PLATE 63 ■ "1 T {/ : . ■ - ,/X . ' S -- ■'*. .••' \ [K 9W& Hanford Fine Sandy Loam — Second Crop Pots of same and different representatives of a given soil type compared. Melilotus indica, following eowpeas. Left to right — Soil 22, Pot 2; Soil 23, Pot ] ; Soil 24, Pot 1; Soil 25, Pot 1. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [ PENDLETON ] PLATE 64 Hanford Fine Sandy Loam — Second Chop Pots of same and different representatives of a given soil type compared. Melilotus indica, following cowpeas. Left to right — Soil 15, Pot 1; Soil 15, Pot 2; Soil 15, Pot 3; Soil 23, Pot 1. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [ PENDLETON ] PLATE 65 IIanf-ord Fine Sandy Loam — Second Crop Pots of same and different representatives of a given soil type compared. Melilotus indica, following cowpeas. Left to right— Soil 23, Pot 2; Soil 23, Pot 3; Soil 25, Pot 1 ; Soil 25, Pot 2; Soil 25, Pot 3. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [ PENDLETON ] PLATE 66 • V ^ ngjjj^— ■^HHBte^^P^^ -^■P\. — -- Haxford Fixe Sandy Loam — Second Crop Pots of same and different representatives of a given soil type compared. Bur clover, following milo. Left to right — Boil 14, Pot 1 ; Soil 15, Pot 1; Soil 16, Pot 2; Soil 19, Pot 1: Soil 20, Pot 1. Haxford Fixe Saxdy Loam — Secoxd Crop Pots of same and different representatives of a given soil type compared. Bur clover following milo. Left to right— Soil 22, Pot 1 ; Soil 23, Pot 1 Soil 24, Pot 1; Soil 2o, Pot 1. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [ PENDLETON ] PLATE 67 Haxford Fine Sandy Loam — Second Crop Pots of same and different representatives of a given soil type compared. Bur clover, following milo. Left to right— Soil 19, Pot 1; Soil 19, Pot 2; Soil 19, Pot 3; Soil 23, Pot 1; Soil 23, Pot 2. *5k t^tit Hanford Fine Sandy Loam — Second Crop Pots of same and different representatives of a given soil type compared. Bur clover, following milo. Left to right— Soil 23, Pot 3; Soil 25, Pot 1 Soil 23, Pot 2: Soil 23, Pot 3. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [PENDLETON] PLATE 68 San Joaquin Sandy Loam Pots of same and different representatives of a given soil type compared. Eye. Left to right— Soil 10, pot 2; soil 11, pot 1; soil 12, pot 2; soil 13, pot 3; soil 17, pot 3; soil 18, pot 1; soil 21, pot 1; soil 26, pot 1. UNIV. CALIF. FUBL. AGR. SCI. VOL. r PENDLETON ] PLATE 69 San Joaquin Sandy Loam Pots of same and different representatives of a given soil type compared. Fig. 1. Melilotus indica. Left to right— Soil 10, pot 1; soil 11, pot 3; soil 12, pot 2; soil 13, pot 1; soil 17, pot 3; soil 18, pot 3; soil 21, pot 2; soil 28, pot 1. [■ ' Lti _ '- ' : '■■ •• 1 \ -' 1 Iff ■I: mm w Br ^ ■ - - '- " -;-> L___' - San Joaquin Sandy Loam Pots of same and different representatives of a given soil type compared. Fig. 2. Melilotus indica. Left to right — Soil 13, pot 1; soil 13, pot 2; soil 13, pot 3; soil 17, pot 1; soil 17, pot 2; soil 17, pot 3; soil 26, pot 1; soil 28, pot 2; soil 26, pot 3. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [PENDLETON] PLATE 70 San Joaquin - Sandy Loam Pots of same and different representatives of a given soil type compared. Eye. Left to right — Soil 10, pot 1; soil 10, pot 2; soil 10, pot 3; soil 18, pot 1; soil 18, pot 2; soil 18, pot 3; soil 26, pot 1; soil 26, pot 2; soil 26, pot 3. UNIV. CALIF. PUBL. AGR. SCI. VOL, 3 [PENDLETON] PLATE 71 San Joaquin Sandy Loam Pots of same and different representatives of a given soil type compared. Fig. 1. Barley. Left to right— Soil 10, pot 3; soil 11, pot 2; soil 12, pot 3; soil 13, pot 1; soil 17, pot 3; soil 18, pot 2; soil 21, pot 3; soil 26, pot 1. San Joaquin Sandy Loam Pots of same and different representatives of a given soil type compared. Fig. 2. Barley. Left to right— Soil 10, pot 1 ; soil 10, pot 2 ; soil 10, pot 3 ; soil 18, pot 1; soil 18, pot 2; soil 18, pot 3; soil 26, pot 1; soil 26, pot 2; soil 23, pot 3. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [PENDLETON] PLATE 72 Jf^fe^WjES! San Joaquin Sandy Loam Pots of same and different representatives of a given soil type compared. Fig. 1. Oats. Left to right — Soil 10, pot 1; soil 11, pot 1; soil 12, pot 2; soil 13, pot 1; soil 17, pot 2; soil 18, pot 3; soil 21, pot 1; soil 28, pot 3. San Joaquin Sandy Loam Pots of same and different representatives of a given soil type compared. Fig. 2. Oats. Left to right— Soil 11, pot 1; soil 11, pot 2; soil 11, pot 3; soil 17, pot 1; soil 17, pot 2; soil 17, pot 3; soil 21, pot 1; soil 21, pot 2; soil 21. pot 3. UNIV. CALIF, PUBL. AGR. SCI. VOL. 3 [PENDLETON] PLATE 73 i > San Joaquin Sandy Loam Pots of same and different representatives of a given soil type compared. Fig. 1. Wheat. Left to right— Soil 10, pot 1. ; soil 11, pot 3; soil 12, pot 1; soil 13, pot ] ; soil 17, pot 1; soil 18, pot 2; soil 21, pot 1; soil 26, pot 3. San Joaquin Sandy Loam Pots of same and different representatives of a given soil type compared. Fig. 2. Wheat. Left to right— Soil 10, pot 1; soil 10, pot 2; soil 10, pot 3; soil 13, pot 1; soil 13, pot 2; soil 13, pot 3; soil 17, pot 1; soil 17, pot 2; soil 17, pot 3. UNIV. CALIF. PUBL. AGR. SCI. VOL. 3 [ PENDLETON ] PLATE 74 fc'- IV.vi i San Joaquin Sandy Loam Pots of same and different representatives of a given soil type compared. Fig. 1. Bur clover. Left to right— Soil 10, pot 2; soil 11, pot 2; soil 12, pot 3; soil 13, pot 1; soil 17, pot 3; soil 18, pot 2; soil 21, pot 1; soil 26, pot 3. San Joaquin Sandy Loam Pots of same and different representatives of a given soil type compared. Fig. 2. Bur clover. Left to right— Soil 10, pot 1; soil 10, pot 2; soil 10, pot 3; soil 18, pot 1; soil 18, pot 2; soil 18, pot 3; soil 26, pot 1; soil 26, pot 2; soil 26, pot 3.