^ ' [% Division of Agricultural Science H ! \" \! UNIVERSITY GRAIN FERTILIZATION IN CALIFORNIA ?S|;S»|fp| 1IFORNIA AGRICULTURAL Experiment Station xtension Service BULLETIN 775 THIS BULLETIN summarizes the results of a five-year field study on grain fertilization. A total of 221 coordinated field tests was carried out in 38 counties by the Agricultural Extension Service in cooperation with the Department of Agronomy. The study was made during the period 1947 through 1951, on farms selected by the University of California Farm Advisors as typical of the grain-producing areas of their counties. Results of this program have been released locally in the counties involved and have formed the basis for fertilizer recommendations for those areas and a starting point for additional local fertilizer tests. The purpose of this report is: 1* To present results of the entire program of field fertilizer tests. 2* To show the fertility status of grainlands in various regions throughout the state. 3* To indicate what fertilizers may most effectively be used on grainlands under the varying systems of culture and climatic conditions of the state. THE AUTHORS: William E. Martin is Agriculturist in Agricultural Extension, Davis. Duane S. Mikkelsen is Associate Professor of Agronomy and Agronomist in the Experiment Station, Davis. ^ The cover picture, taken in 1950, shows the area cropped for 75 years. The alternate strips illustrate the farmer's method of determining the actual benefits of fertilizer recommendations developed from Univer- sity test plots in the area. In this case a fertilizer attachment was placed on one of the two grain drills pulled in tandem in seeding the field. Approximately 90 pounds per acre of "16-20" ammonium phosphate sulfate were applied. NOVEMBER, 1960 PURPOSE AND METHODS B >arley, wheat, and oats are grown on a larger total acreage than any other single cultivated crop in California. Fig- ures from the California State Crop and Livestock Reporting Service, for the years 1956, 1957, and 1958, show an average of 1,885,000 acres of barley, 350,000 acres of wheat, 205,000 acres of oats, and 528,000 acres of grain hay har- vested in the state. Grain is grown com- mercially in nearly every county, and is a major crop in all important agricul- tural counties from Imperial and San Diego on the south to Siskiyou and Modoc on the north. Grain is grown under a wide variety of climatic conditions. In irrigated areas it is commonly grown in rotation with other crops. In many other areas it is grown without irrigation, under an alter- nate grain-fallow system where rainfall is not sufficient for annual production. In some areas of California where rainfall is adequate, grain is grown annually without irrigation. Grain has been a major crop in Cali- fornia for about a hundred years, and was the first important field crop grown on any extensive acreage. In many areas it was formerly grown annually, with the stubble burned following each crop. Many lands now in production have been raising grain annually or biennially for 60 to 80 years. In some regions where grain has been grown continuously for 50 years or more, soil fertility has been seriously depleted, and in many instances, soil structure has been impaired and soil organic matter greatly reduced. Samples were taken in Monterey County from a field devoted to grain for approximately 75 years. An adjacent piece of land of the same soil series was cleared of brush and oak and added to the original grain field in 1949. Soil samples were taken from the two sections of the field in 1953. The newly cleared land, after two years of cropping, contained 3.6 per cent organic matter, as compared with only 1.35 per cent in the field cropped for 75 years. This would indicate a loss of 63 per cent of the orig- inal organic matter during the period of cropping. (See cover photograph, and legend inside cover.) Production of cereals on some of the older grain areas has dropped to uneco- nomic levels. Some such soils are com- monly referred to as "wornout grain- lands." Some have reverted permanently to use as range, while others are cropped only occasionally, with several years of pasture between crops of grain. With the pressure of expanding agriculture in Cali- fornia and an increase in land values, it is important that means be developed to improve the productivity of wornout grainlands and maintain and improve productive capacity of the better land now devoted to grain production. One of the principal purposes of the current study was to determine to what extent commercial fertilizers might restore the productivity of depleted grainlands and a second, to determine what fertilizer should be applied to currently productive land to bring about production as great as is economically possible under the cli- matic conditions of the areas involved. A further objective of this coordinated study was to develop an inventory of in- formation on the fertility status of a wide range of California soils and to classify those groups and series where fertility problems might be corrected by the use of commercial fertilizers. [3 Fig. 1. Effect of nitrogen and phosphorus on yield of annual barley. Above: phosphorus with no nitrogen. Below: phosphorus with 15 pounds nitrogen per acre. How Field Tests Were Conducted Previous fertilizer work in many of the counties of the state had indicated that nitrogen and phosphorus were the nutrients most likely to increase yields. In the earlier tests, however, no concerted effort was made to correlate soil series with fertilizer response or to lay out tests in such a way that the effects of individ- ual fertilizer nutrients might be studied alone and in combination with each other. Much valuable local information was developed in these tests, but the rate and time of application and the materials employed differed so greatly that results could not be assembled and compared on a statewide basis. The present study, described in the sec- tions that follow, was made up of 221 tests, including locations in all of the principal grain-producing areas of the state. Of these tests, 149 were with barley, 62 with wheat, and 10 with oats. Forty- five were on irrigated lands, while 176 were on lands dependent on natural rainfall. The first 25 tests were exploratory in nature, designed to determine what nu- trients were deficient. Such tests involved applications of nitrogen, phosphorus, and potash, each nutrient alone and in com- [4 ^:;£l^^ f^lJKIHJ E3 p ,: V< -.:4 «8 ^#^1^ V- ',-"4 V,*' '■>il v' \ t&gk Fig. 1A. Effect of nitrogen and phosphorus on yield of annual barley. Above: phosphorus with 30 pounds nitrogen per acre. Below: phosphorus with 45 pounds nitrogen per acre. bination with each of the others. Ferti- lizer materials were broadcast at planting time and applied in strips to facilitate visual comparison. At some locations the exploratory tests were expanded to in- clude sulfur. The second group of 196 tests con- sisted of rate experiments set up to deter- mine how much nitrogen and phosphorus should be applied for most efficient grain production. The treatments in these ni- trogen-phosphorus rate tests employed four rates of nitrogen and, at each nitro- gen level, four rates of phosphorus. This gave a total of 16 treatments, which were replicated four times in most instances. During the first two seasons, 1947 and 1948, rates of 0, 10, 20, and 40 pounds of nitrogen were used, along with 0, 10, 20, and 40 pounds P 2 0- per acre at each nitrogen rate. In the last three years, ni- trogen rates were changed to 0, 15, 30, and 45 pounds, and phosphorus applica- tions to 0, 20, 40, and 80 pounds P 2 5 at each nitrogen level. In the first two years, fertilizer materials were broadcast at planting time and land was seeded in the customary fashion by the farmer coop- erator. In such tests, individual subplots were 20 feet by 20 feet. Beginning in 1948, a modified rod row technique was employed, similar to that [5] Nitrogen Yield PER ACRE* OF BARLEY WITH P 2 5 APPLIED AT: applied lb/A 20 lb/A 40 lb/A 80 lb/A lb/A lb lb lb lb 758 1,028 1,080 1,163 15 945 1,470 1,665 1,910 30 863 1,583 1,778 1,958 45 1,237 1,560 its = 411 lb/acre. 1,875 2,048 * LSD (0.05) between treatmer used for testing grain varieties. In these tests each treatment consisted of three rows of grain, 20 to 40 feet long and 1 foot apart, with 16 feet of the middle row harvested for yield. The fertilizer mate- rials used in the rod row tests were mixtures of ammonium sulfate, single superphosphate, and sand, varying in composition so that a rate of 480 pounds per acre gave the requisite amounts of nitrogen and phosphorus in a single ap- plication. After the fertilizer had been applied in rows 2 to 3 inches deep and 1 foot apart, grain was seeded with a single- row, hand-seed drill 1 inch to the side and 1 inch above the fertilizer band. A typical rod row fertilizer test with annual barley on a soil responding to both nitrogen and phosphorus is shown in figures 1 and 1A. Pounds per acre of barley at harvest from this test were as shown in the table above. All fertilizer plots were put out by Uni- versity of California Farm Advisors, in fields selected as typical of the grain- producing areas of their counties. The same variety and kind of grain were seeded as were used in the balance of the field. Rod row plots were weeded as nec- essary during the growing season. At harvest time, 16 square feet from each treatment were clipped by hand, and the clippings were placed in paper bags and sent to the Department of Agronomy at Davis for yield and quality evaluation. How Results Are Expressed Yields were calculated on a weight basis, with results expressed as pounds of grain per acre rather than bushels, as commonly used in other sections of the country. Amounts of nitrogen applied as fertilizer always refer, in this bulletin, to pounds of actual nitrogen per acre. In discussing the effects of fertilizer on qual- ity of grain, nitrogen values were con- verted to per cent protein. Fertilizer phosphorus applications are usually expressed as pounds of available P 2 5 per acre. In this bulletin, where ref- erence is made to fertilizer applications and their effects, the terms P, P 2 5 , and phosphorus have been used interchange- ably, but amounts always refer to pounds of P 2 5 per acre. In the section on soil analysis, results of tests for available phosphorus are expressed as phosphate (P0 4 ). Laboratory and Greenhouse Studies Soil samples for laboratory and green- house studies were taken at time of plant- ing from as many locations as possible (Jenny et al, 1950) - 1 A total of 159 sam- ples was taken from the 221 field tests in this study. After threshing, grain samples were set aside from selected plots for chemical studies and bushel weight meas- urements to determine the effects of fer- tilizer treatments upon quality of the grain. Subsequent to the field studies, de- tailed laboratory examination was made of the soil samples to correlate soil analy- sis with the fertilizer results obtained. The object was to find a reliable method for prediction of cereal ferti- lizer needs. 1 See "Literature Cited" for citations referred to in the text by author and date. 6] SUMMARY OF RESULTS — STATEWIDE What Nutrients Increased Yields? Results of 221 field tests in 38 counties showed some very striking responses to fertilizers. In 74 per cent of these tests, yields were improved, while 26 per cent showed no benefit from fertilization. The proportion of soils found deficient in each nutrient is shown in figure 2. A summary of the observed responses to fertilization in each of the 38 contribut- ing counties is shown in Appendix table 1A (p. 37). A quarter of the 221 areas tested either did not need fertilization or failed to re- spond because of inadequate soil mois- ture. About a third of the tests responded to nitrogen alone but showed no benefit from phosphorus. A sixth, or 16 per cent, responded to phosphorus alone with no effect of nitrogen, while 26 per cent needed both nitrogen and phosphorus for maximum yield. Grainlands were classified as phospho- rus-deficient (1) where phosphorus alone increased yields or (2) where phospho- rus plus nitrogen gave higher yields than nitrogen alone. Combining the two classes of response in which phosphorus was beneficial shows that 42 per cent of the grainlands was deficient in phos- phorus. Similarly, tests were considered to show nitrogen response (1) where nitro- gen alone increased yields or (2) where nitrogen plus phosphorus gave signifi- cantly higher yields than phosphorus alone. Combining these two groups indi- cates 59 per cent of the grainlands sam- pled to be deficient in nitrogen. No coordinated tests were conducted with potash fertilizers over the entire area. However, in conjunction with the tests above, 34 field tests were laid out in which nitrogen plus phosphorus treat- ments were compared with the same amounts of nitrogen and phosphorus plus potassium. In no case was there a signifi- cant response to the added potassium. Sulfur is known to be a factor in grain production at some locations, but areas and effects cannot be delineated. Where Were Phosphorus Deficiencies Found? Regions of phosphorus deficiency The responses to fertilization have been plotted on the map of California shown in figure 2. It may be seen that phosphorus-deficient soils occur in many sections of the state. The most striking zone occurs on the terraces and foothills at the east edge of the San Joaquin and Sacramento valleys, extending from Por- terville on the south to Oroville on the north. A similar group of plots showing phosphorus deficiency lies on the western edge of the Sacramento Valley. The other two principal zones are in coastal San Diego and Orange counties and in the region between Paso Robles and Shan- don in San Luis Obispo County, as well as in the near-by Lockwood Valley of Monterey County. Some tests on peat lands in the Sacramento-San Joaquin Delta showed response to phosphorus. Regions not responding to phosphorus Tests in Imperial Valley showed no response to phosphorus, and yields in most cases were increased by nitrogen. Similar tests in the trough of the San Joaquin and Sacramento valleys showed little phosphorus deficiency, and yields were either increased by added nitrogen or failed to respond to any added fer- tilizers. Similarly, tests in the mountain [7] FERTILIZATION OF CEREALS Results of 221 Field Tests TREATMENT GIVING HIGHEST YIELD « NITROGEN ALONE 32% • NITROGEN and PHOSPHORUS 26% • PHOSPHORUS ALONE 16% \ NO FERTILIZER EFFECT 26% - Fig. 2. Map shows proportion of soils found deficient in nitrogen and phosphorus in 38 counties. [8] valleys of northeastern California rarely showed response to added phosphorus, but usually showed increased yield from nitrogen. Lack of phosphorus response in the Imperial Valley may be attributed to the fact that grain there usually fol- lows crops such as alfalfa or vegetables, which are often heavily fertilized with phosphorus. What Soil Series and Groups Needed Phosphorus? In the preceding section it was shown that soils in some physiographic zones of the state usually responded to phospho- rus, while others appeared well supplied as judged by field fertilizer tests. Of the 221 tests in this study, 192 were on soils mapped by soil surveys, and the soil series at each location could be identified. These tests, representing 74 different soil series, have been assembled in soil profile groups according to Storie and Weir's (1953) classification of California soils, and the results are summarized in table 1. Soils of Groups I and II are relatively >oung soils occurring on recent alluvial ans and flood plains. These soils show slight profile development, being rela- tively uniform in texture and generally leep and permeable. Only 11 of the 59 tests on soils of this type (19 per cent) showed response to added phosphorus. Typical Group I and II soil series are Columbia, Vina, Greenfield, and Yolo. Phosphorus deficiency was observed on the Arbuckle, Chino, and Egbert series and on some of the calcareous series, such as Cajon, Chino and Adelanto, and Melo- land. Group III soils represent older soils on plains or old alluvial fans. These soils show some clay accumulation at depth, and are not usually so well drained nor permeable as the younger soils of Groups I and II. Eleven of the 36 tests on soils of this group (30 per cent) showed re- sponse to added phosphorus. Harrington, Myers, and Gridley are typical series of this group adequately supplied with phosphorus, while some deficiency was observed in tests on the Lockwood, Ducor, and Ramona series. Group IV soils represent still older soils, usually on old terrace formations or ancient plains, and have a strong ac- cumulation of clay at depth. These soils usually are referred to as "claypan" soils, and are characterized by poor internal drainage, particularly in wet years. Eighteen of the 25 tests on soils of this group (72 per cent) responded to added phosphorus. Corning, Watsonville, and Huerhuero are typical series of this group responding to phosphorus. Group V soils again represent old soils, Table 1. — Relation of Soil Profile Group to Response of Grain to Nitrogen and Phosphorus Fertilizers (1 73 tests on 74 soil series) Number of: Tests showing response to : Deficient in : Soil profile groups Soil series Field tests None N only N +P Ponly N P I. Recent alluvial soils II. Young alluvial soils 18 9 14 13 10 10 38 21 36 25 30 23 per cent 36 29 28 20 10 4 per cent 45 52 42 8 7 17 per cent 8 14 8 48 50 44 per cent 11 5 22 24 33 35 per cent 53 66 50 56 57 61 per cent 19 19 III. Older alluvial soils 30 IV. Claypan soils 72 V. Hardpan soils 83 VII, VIII, IX. Upland soils 79 [9 usually on ancient terraces or old alluvial plains, but characterized by the presence of a cemented hardpan layer, often with some clay accumulation immediately above the hardpan. These soils are often quite shallow because of the hardpan formation below, and tend to become waterlogged in wet years and droughty in dry seasons. Twenty-five of the 30 tests on soils of this group (83 per cent) responded to added phosphorus. San Joaquin and Rocklin are typical series in this group responding to phosphorus. Groups VII, VIII, and IX represent upland soils developed in place by the weathering of either hard rock or softly consolidated material. This is a broad grouping, including soils of widely dif- fering parent material. Eighteen of the 23 tests on these upland soils (79 per cent) showed response to phosphorus. Linne, Altamont, and Vista are typical soils of this general group. Phosphorus deficiency was clearly re- lated to soil profile group and series as discussed above and shown in table 1. Most of the irrigated grain is produced on recent or young alluvial soils (Groups I, II, and III) which are relatively well supplied with available phosphorus. Con- versely, nonirrigated grain is cultivated principally on older soils occupying ter- race positions (Groups IV and V) or on upland soils (Groups VII, VIII, and IX) which commonly are deficient in phos- phorus. No definite relationship between soil group and nitrogen deficiency was ob- served. The proportion of soils in all groups responding to nitrogen either alone or with phosphorus remained about the same. The observed fertilizer responses of each of the 74 soil series are shown in Appendix table 2A (pp. 38-39). Soil Analysis Indicates Need for Phosphorus Soil analysis offers a satisfactory means of predicting whether or not a soil to be planted with grain needs an application of phosphorus. Subsequent to the field studies on grain fertilization, a study was made of soil samples taken from the sites of the field tests prior to planting and applying the fertilizer mate- rials. Samples from 101 out of the 221 field tests were available for study. These were analyzed for phosphorus, in the lab- oratory, by several different methods. The water-soluble phosphorus extraction method of Bingham (1949) and the bi- carbonate extraction method of Olsen (1954) were the only tests offering prom- ise over the wide range of soils in this study. Prediction of phosphorus response by water-soluble phosphate extraction This method gave 92 per cent accuracy of prediction, using a threshold value of 0.4 ppm P0 4 in the l-to-10 water extract. Results with this method, shown in table 2, indicate the proportion of tests re- sponding to phosphorus over a wide range of soil phosphate values. It will be noted that below 0.1 ppm, all samples were from plots which gave field response to phosphorus application. Between 0.1 and 0.2 ppm, 96 per cent of the samples gave phosphate response. Above 0.4 ppm, only one sample showed field response to phosphorus. Using the 0.4 value as threshold, 52 of the 59 samples in which phosphorus response was predicted actu- ally gave a response, or an accuracy of 88 per cent. Of the values above 0.4, which should not have given a response, only one error was made, for an accuracy 10] Table 2. — Prediction of Phosphorus Response of Grain by Use of Soil Analysis Water phosphate extraction Bicarbonate phosphate extraction Range of PO4 values* No. of tests No. of re- sponses to phosphorus Phosphorus response Range of PO4 values t No. of tests No. of re- sponses to phosphorus Phosphorus response ppm in water 0-0.1 0.1-0.2 0.2-0.3 0.3-0.4 13 23 16 7 13 22 12 5 per cent 100 96 75 71 ppm in water 0-0.4 0.4-0.7 0.7-1.0 16 23 17 16 21 14 per cent 100 91 82 1.0-1.3 1.3-1.6 1.6-1.9 1.9-2.2 2.2-2.5 2.5-2.8. .... 2.8-3.1...... 3.1-3.4 ..... 3.4-3.7...... 3.7-4.0...... Over 4.0. . 2 4 2 3 6 5 4 2 5 6 6 1 1 0.4-0.5 0.5-0.6 0.6-0.7 0.7-0.8 0.8-0.9 0.9-1.0 1.0-1.1 1.1-1.2 1.2-1.3 Over 1.3. .. . 5 1 7 5 3 1 4 4 3 9 1 20 25 17 * Using 0.4 ppm as threshold: 52 responses Below 0.4 59 total t Using 1.0 ppm as threshold: 51 responses = 88% accuracy Below 1.0 = 91% accuracy 56 tests 53 no responses 41 no responses Over 0.4 — = 98% accuracy Over 1.0 — = 96% accuracy. 42 total 55 tests in this zone of 98 per cent. Some of the tests in which phosphorus response was predicted but not obtained were at rela- tively dry locations where there was not enough growth to respond to any ferti- lizer application. Prediction of phosphorus response by means of bicarbonate extraction This method gave equally good results. If 1 ppm P0 4 in the soil extract were taken as threshold value (equivalent to 30 pounds P 2 5 per acre 6 inches), the method would have predicted observed results correctly with 94 of the 101 tests, an over-all accuracy of 93 per cent (table 2). Only two samples in the high-phos- phorus range indicated that the field had benefited from added phosphorus. The bicarbonate method is not recommended for use on peat or muck soils because re- sults are erratic and unpredictable. Soil analysis does not predict how much phosphorus to use The necessity of adding phosphorus to soils planted to cereals can be predicted quite accurately by soil analysis. No rela- tionship was found, however, between the values attained by either method of analysis and the amount of phosphorus that had to be applied for maximum pro- duction. Soil analysis for phosphorus did not predict the intensity of the phospho- rus deficiency nor the degree of benefit in production which might be expected on soils classified as phosphorus-deficient. [ii] Soil Analysis Fails to Predict Need for Nitrogen A study of 122 soil samples from test sites revealed no relationship between re- sponse to nitrogen and amounts of either nitrate or ammonia nitrogen present at time of sampling. Supplies of available nitrogen in the soil are subject to drastic changes with moisture and temperature fluctuations. Rapid losses of nitrates may result from leaching or denitrification. On the other hand, high soil temperatures may cause rapid increases of available Table 3. — Per Cent of Tests Showing Increased Yield from Nitrogen Tests showing increase Irrigation status Following cereal or other non- legume Following legume, fallow, or on an organic soil Irrigated grain Nonirrigated grain . . Average per cent 69 73 72 per cent 11 49 46 nitrogen through speedup of decomposi- tion of organic materials. Low tempera- tures will slow down the nitrification process. As a result, it is hardly unex- pected that neither nitrate nor ammonia nitrogen, at planting, was found defi- nitely related to nitrogen supply during the crop season. Nitrogen Response Related to Preceding Crop History The necessity of applying nitrogen to grainland is closely related to cropping history. This relationship is shown in table 3. Need for nitrogen was shown in approximately 72 per cent of tests in which either irrigated or nonirrigated grain followed cereal or other nonle- gumes. Since nitrogen responses were seldom observed on organic soils, results from such soils have been grouped with results either on fallow land or where a legume preceded the grain. On such land, fallowed or cropped to legumes the pre- ceding season, 46 per cent of tests re- sponded to nitrogen. There was no clear relationship between preceding crop his- tory and response to added phosphorus. FERTILIZATION OF NONIRRIGATED GRAIN Relation of Rainfall and Crop History to Fertilizer Response Production of grain under nonirri- gated conditions is greatly affected by soil moisture and rainfall distribution, as well as by soil management and fer- tilizer practices. Where rainfall is less than 12 inches, grain is usually grown biennially on land allowed to lie fallow during the preceding season. Where rain- fall is over 16 inches, grain is often grown every year on the same land. In the intermediate zone, with rain of 12 to 16 inches, a fallow system is usually em- ployed, but occasionally consecutive grain crops may be grown. A total of 176 fertilizer tests was run on nonirrigated grain. They showed 28 per cent of soils deficient in both nitrogen and phosphorus, 30 per cent deficient in nitrogen alone, 18 per cent deficient in phosphorus alone, and 24 per cent that did not respond either to nitrogen or phosphorus fertilizers. Thus deficiencies of both nitrogen and phosphorus are common on nonirrigated grainland. Soil nitrogen was found deficient in 58 per cent of nonirrigated grainland soils. [12 The available supply from soil organic matter had been reduced by years of con- tinued production. Where annual crop- ping occurs, crop needs usually exceed natural soil supplies of nitrogen. The supply of available nitrogen may increase during the fallow year through activity of nonsymbiotic nitrogen-fixing organ- isms and through the slow decomposition of soil organic matter and recent crop residues. Accumulated nitrates may re- main for crop use or become lost by leaching, if rainfall is excessive, or by denitrification if the soil becomes water- logged. Thus, both rainfall and crop se- quence may be expected to affect the results of and need for nitrogen fertili- zation. Soil phosphorus was found inadequate in 46 per cent of field tests run. The supply of available phosphorus seems most directly related to the chemical nature and age of the soil and probably to the length of time the land has been cropped to grain without phosphorus fer- tilization. Thus, phosphorus supply is not affected by current soil cropping prac- tices. During the crop year, phosphorus responses may be magnified by cold tem- peratures during winter months. With warm, spring temperatures, responses may become less evident. The relationship of rainfall and crop sequence to the frequency of nitrogen response is summarized in table 4. These figures show the proportion of the tests in which nitrogen increased yield. The data include measurements from soils de- ficient in phosphorus as well as from soils adequately supplied with this nutrient. A response to nitrogen was recorded when the yield from added nitrogen treatments was significantly greater than that from the corresponding treatment without ni- trogen. Thus, on high phosphorus soils, a nitrogen response represented yield in- creases from nitrogen alone. On phos- phorus-deficient soils, a nitrogen response represented a yield increase after the ini- tial deficiency of phosphorus had been corrected. Such soils often show little or no effect of nitrogen alone. An examination of the rainfall effects shows that the likelihood of benefit from nitrogen fertilizer increased as the rain- fall became greater. With annual barley, only 20 per cent of the tests showed bene- fit of nitrogen where rainfall was below 10 inches. In the 10- to 12-inch rainfall group, 46 per cent showed increase, while in the tests with over 12 inches of rain, 96 per cent showed significant benefit of nitrogen fertilization. On fallow barley, only about a third of the tests in which rainfall was below 12 inches showed benefit from nitrogen application, while somewhat over a half showed a nitrogen response when the rainfall was over 12 inches. Similar results were observed on fallow wheat, with 50 per cent of the tests above 10 inches showing benefit from fertilization. With rainfall less than 10 Table 4. — Relation of Rainfall and Crop Sequence to Occurrence of Nitrogen Deficiency of Nonirrigated Grain Kind of grain culture No. of tests Tests responding to nitrogen with seasonal rainfall of : Under 10" 10-12' Over 12' Annual barley . . Fallow barley . . Fallow wheat . . Average total 42 49 40 per cent 20 30 31 per cent 46 35 50 per cent 96 56 50 131 29 43 [13] 68 inches, only 31 per cent of wheat tests showed benefit from nitrogen. Both rainfall and crop sequences affect the likelihood of benefit from nitrogen applications. When land is cropped an- nually, there is no opportunity for mois- ture or nitrogen to accumulate. When land is fallowed prior to cropping, mois- ture may be stored in the soil, and avail- able nitrogen supplies also build up. In addition, the fallow year gives an op- portunity for reduction of annual weeds. It is well known that grain yields are less under drought conditions than when adequate moisture is present. It is also a common observation in California that in years of high rainfall, when soils be- come waterlogged, grain yields are poorer than when lesser but adequate amounts of rain are evenly distributed throughout the growing season. The ef- fect of excess soil moisture in causing poor grain performance may be ex- plained on the basis either of increased root diseases or loss of available nitrogen through leaching or denitrification. Im- paired aeration also has an adverse effect on production. It would be expected that, under low rainfall conditions, moisture rather than fertility would be the factor limiting yields. With adequate rainfall, fertility may be expected to limit production. The benefit of added nitrogen should become greater as rainfall increases and losses of accumulated nitrogen take place. It is recognized that the distribution of rain- fall throughout the growing season may be as important as the total amount dur- ing that period. Similarly, the slope, tex- ture, permeability, and water-holding capacity, along with the density of plant population, will influence crop behavior, both during periods of drought and pe- riods of excess rainfall. Recognizing these limitations, attempts were made, as reported in the following sections, to re- late total seasonal rainfall, recorded at the nearest weather station, to observed crop behavior and fertilizer response. Annual Barley A total of 40 replicated rate tests with barley was carried out on annually cropped grainlands. Twenty-five of these rate tests showed no response to phos- phorus (table 5), while 15 showed sig- nificant effects of phosphorus, alone or with nitrogen. * V lr < * 1 - J ~« < -* 4 . 4 Table 5. — Effect of Nitrogen on Yield and Profit from Fertilization 4 (Soils not responding to phosphorus! Seasonal rainfall Sig. N* Base yield Av. increase from: ^ >- Range Average No. tests N 15 N 3 o N45 A inches Below 10 inches 8.71 10.87 15.99 2 2 6 15 17 lb /A 743 1,871 1,448 lb/A 45 252 294 lb /A -15 250 527 W . A -37 10-12 181 *" T Over 12 605 ^ 4 * Sig. N Number of significant responses to N No. Number of tests in each group t Average profit = value of increased yield at $2/cwt, less cost of N at 13.3 cents/lb. % Frequency = per cent of tests in which treatment was profitable. [ 14 On soils not responding to phosphorus Two of the 25 tests were in areas where the annual rainfall for the crop season was below 10 inches. The yield without treatment was 743 pounds of barley per acre. The 15-pound nitrogen treatment showed a slight increase of 45 pounds of barley per acre, while the 30- and 45- pound rates showed small decreases. None of these differences with low rain- fall was statistically significant at the 5 per cent level. Six tests in the 10- to 12-inch rainfall group resulted in an average yield of 1,871 pounds without fertilization. In two of the six, yields were significantly increased by the application of nitrogen. In several of the other tests, yields were increased numerically, but the differences were not statistically significant. The av- erage yield increase of all six plots in this rainfall zone was 252 pounds of barley from 15 pounds of nitrogen, with slightly smaller increases where more nitrogen was employed. Seventeen plots were in the high-rain- fall group of 12 inches or more seasonal rainfall. The average recorded rainfall of Annual Barley *. Av. profitf /acre, and frequency { Nl5 N.30 N 45 ' -$1.10 -$4.30 -$6.74 - 0% 3.04 r 0% 1.00 50% 6.54 88% 0% -2.38 83% 3.88 71% 50% 6.10 88% from the nearest official weather stations was about 16 inches. In this group, 15 of the 17 tests showed significant yield in- creases from the application of nitrogen. The average increase of all tests amounted to 527 pounds per acre from 30 pounds of nitrogen, and 605 pounds per acre where 45 pounds of nitrogen were ap- plied. The 15-pound nitrogen rate was not enough nitrogen for satisfactory pro- duction with this amount of rainfall. Evaluation of results. Results of ni- trogen fertilizers on annual barley were evaluated in terms of their dollar value. Profit from fertilization was calculated by deducting the cost of the nitrogen applied from the value of the increased yields of barley. Barley was evaluated at $2 per hundred weight (cwt). Nitrogen costs were established at 13.3 cents per pound. Using this value, 15, 30, and 45 pounds of nitrogen cost $2, $4, and $6, respectively. On this basis it would re- quire 100 pounds of barley to pay for each 15-pound unit of nitrogen applied. It is important to evaluate results of a fertilizer test on the basis of their eco- nomic significance in dollar value rather than to rely solely upon statistically sig- nificant yield differences. A simple eco- nomic relationship has been used here to provide a quick approximation of the value of fertilization. In the two tests carried out in areas with less than 10-inch rainfall, the yields were not significantly affected, but the losses in operating costs which would have resulted from application of ferti- lizer material are important economi- cally. Clearly, a hazard of using fertilizer under low rainfall conditions would be the likely loss of $4.30 to $6.74 an acre if 30 to 45 pounds of nitrogen were used. Results in the 10- to 12-inch rainfall zone show that the average yield increase of 252 pounds per acre from 15 pounds of nitrogen would pay the fertilizer cost of $2 and in addition return a profit of $3.04 per acre. With 30 pounds of nitro- gen and no additional yield increase, the [15] operation would remain profitable, but at the rate of only $1 an acre. If 45 pounds of nitrogen were used, a loss of $2.33 per acre would be sustained. Where annual rainfall was over 12 inches, fertilization was profitable in most cases. With 30 pounds of nitrogen, the value of the increased barley produc- tion was $6.54 an acre more than the cost of the fertilizer. Slightly less profit was indicated where 45 pounds of nitrogen were used. In contrast, the 15-pound rate of nitrogen was clearly not enough, and returned an average profit of only $3.88 per acre. The frequency of profitable response from fertilization is of importance. In the group of tests in the 10- to 12-inch rainfall group, 83 per cent, or five out of six of the tests fertilized with 15 pounds of nitrogen, showed yield values in- creased enough to pay for the fertilizer and return a profit. The average profit of all six locations was $3.04. In the over-12-inch rainfall zone, 88 per cent of the tests showed profitable re- sults of fertilization with 30 to 45 pounds of nitrogen. There would seem to be little to justify the use of the higher nitrogen rate on annual barley. If nitrogen were available at 10 cents per pound, the profit per acre would be virtually the same for the 30- and 45-pound rates. On phosphorus-deficient soils Fifteen rate tests were carried out on soils responding to phosphorus. Sixteen different treatments were employed, using nitrogen at 0, 15, 30, and 45 pounds per acre, with phosphorus treatments of 0, 20, 40, and 80 pounds P 2 5 per acre at each level of nitrogen. Results of these tests have been separated on a basis of seasonal rainfall, and are shown in figure 3. INCREASE IN YIELD OF ANNUAL BARLEY On Nonirrigated P-deficient Soils from NITROGEN and PHOSPHORUS FERTILIZERS Ro infall 10- 12 inches Av.no, o 7 T..ti Cwt/A Rain 10.86 B se Yield 1202 lb, 8 • ..©■■■■ \ * 7 - % -=£ o c 81 = I* 1 2 22 * o 00 4) 3 a s g. © M -a s co 3 c8 *>v CO w M O (d o & V bo 2 CO >• B 55 si ll S o is to ca CO h o a CO bo g ^ s 00 ? S? £ ! 6? T I 00 c- I oo o I co 5ra ho CD O 3 £ Cv flj O o- S3 «e g * -- ca ca co "3 .2 51 CD O 8 a I ii CD fl bo £ ca 3 i £ are presented and evaluated both on the basis of yield increases and of profit from the use of fertilizer. In making the latter calculations the increased production from fertilization was given a value of $2 per cwt for barley and S3 per cwt for wheat. Profits per acre for fertilization were calculated by deducting the cost of the nitrogen applied at 13.3 cents per pound and the phosphorus at 10 cents per pound P 2 : , applied per acre. The value remaining was tabulated as profit, and used as a means of determining how much fertilizer may be economically used. On soils not responding to phosphorus Results of 29 rate tests with irrigated grain on soils showing no benefit from added phosphorus are summarized in table 8. Tests with both barley and wheat were divided on the basis of preceding crop history. Those following cereal or other nonlegumes were put into one group, while those tests either preceded by a legume or a period of fallow, or located on organic soil were grouped in the second class. Since no significant effect of phosphorus was shown in any of these tests, the results are tabulated as nitrogen rate experiments. Yields of grain after cereal or other nonlegumes. Yields of grain after cereal or other nonlegumes were usually increased by nitrogen applica- tions. Highest average barley yields were obtained with 80 pounds of nitrogen, but 45 pounds per acre gave nearly as great an average profit per acre as did the higher amount. Frequency of profitable response to nitrogen also is indicated in table 8. These values represent the pro- portion of individually profitable tests at each nitrogen level. Thus, at 45 pounds of nitrogen, 11 of 15 (73 per cent) tests were profitable (average profit of all 15 tests, $7.66) , while in four tests the value of extra barley was less than the cost of nitrogen used. The yield figures with 80 pounds nitrogen were obtained from only seven tests. Three of these gave very high individual profits because of acute nitro- gen deficiency, while in the other four tests small "losses" resulted. The average "profit" was $8.16 per acre, but fre- quency of profit was only 43 per cent. From these results it would appear that treatments of 30 to 45 pounds nitrogen per acre would most likely represent the desirable amount of nitrogen to apply. Results of eight wheat tests following cereal or other nonlegumes were similar to those for barley, with maximum profit and frequency of profit from 45 pounds of nitrogen per acre. Yield after legume or on organic soils. Yield of grain cither following a legume or on organic soils was quite dif- ferent. Neither barley nor wheat showed significant response to nitrogen. The use of unneeded nitrogen on such soils, how- ever, would have resulted in highly im- portant economic losses of $3 to $13 per acre, with barley, and from $1 to $3.50 in the case of wheat. On phosphorus-deficient soils Ten rate tests were conducted on irri- gated soils deficient in phosphorus. As before, results were grouped on the basis of preceding crop and nature of the soil. The three wheat tests were either on or- ganic soils or followed a leguminous crop. Six of the seven barley tests fol- lowed cereal or nonlegumes on mineral soils, with only one on an organic soil. Effects of nitrogen and phospho- rus on yield of barley following a cereal or nonlegume. These effects are shown graphically in figure 6. The average yield increases from various amounts of nitrogen and phosphorus are plotted out. The average profit per acre and frequency of phosphate response for each of the 15 fertilizer treatments are listed in the diagram below the chart. It will be noted that yields were increased by phosphorus alone, but the greatest production was obtained where both ni- [26] INCREASE IN YIELD OF IRRIGATED BARLEY > from use of P and N FERTILIZERS on P- DEFICIENT SOILS Pounds P 2 0r Applied per Acre PROFIT PER ACRE AND FREQUENCY OF PROFIT From Use of Phosphorus and Nitrosen N Used NoP P 20 P 40 p eo None $4.98 67% $7.06 50% -$ .64 50% N 15 $2.42 67% 15.14 100 13.40 83 5.66 67 N 30 1.50 67 13.02 100 14.76 83 8.16 67 N 45 - .32 33 13.08 100 12.72 100 12.96 100 Fig. 6. Results of six rate tests with irrigated barley following a cereal or nonlegume, on mineral soils. [27] Table 9. — Effect of Phosphorus on Yield of Irrigated Grain on Soils Deficient in Phosphorus Either Following Legume or on Muck Soil Kind of grain Base yield Increase due to: Av. profit*/ acre from: P20 P40 Pso P20 P40 P*o Barley (1 test) lb/A 3,805 3,176 lb/A 383 302 lb/A 418 473 lb/A 311 536 $5.66 7.06 $4.36 10.19 Wheat (3 tests) $8.08 * With wheat at $3/cwt, barley at $2/cwt, less P2O5 at 10 cents/pound. trogen and phosphorus were used. With 15 and 30 pounds of nitrogen, the curves reach their highest point at 20 to 40 pounds of P 2 5 per acre. Where 45 pounds of nitrogen were used, the great- est average yield was obtained with 80 pounds of phosphorus. The maximum average profit per acre was obtained from 15 pounds of nitrogen and 20 pounds of phosphorus. The N 30 P 40 treat- ment gave a profit of about the same magnitude. All combined nitrogen-phos- phorus treatments of P 20 and P 40 were profitable at all rates of nitrogen added. The profit figures, however, would indi- cate little advantage to using over 15 to 30 pounds of nitrogen. In cases where nitrogen has been depleted by several successive crops of grain, higher rates of nitrogen would be indicated. There would seem to be no reason for using over 40 pounds of P 2 3 per acre. On organic soils or following a legume. In these situations, irrigated grain showed little benefit from added nitrogen, and principal benefits were from phosphorus. One barley and three wheat tests were available for com- parison. Yield of irrigated barley on Egbert muck is listed in table 9. In this single test, phosphorus increased yields by roughly 10 per cent. There was no con- sistent nor significant effect of added ni- trogen alone or with phosphorus. On this soil, 20 pounds P 2 5 per acre gave a profit of $5.60 per acre for an expendi- ture of only $2 per acre. It would be ex- pected that in some of the valleys of California where low spring temperatures prevail, some nitrogen would be desirable on similar phosphorus-deficient organic soils. Irrigated wheat results were similar to those for barley. In three tests there was no significant effect of nitrogen alone or with phosphorus. Applications of phos- phorus, however, were all profitable, with the highest profit from 40 pounds P 2 5 of $10.10 per acre for a cost of only $4 per acre. In one test in the Blythe area, where wheat was planted after plowing down an old stand of alfalfa, yields were not improved by either nitrogen or phos- phorus alone, but a good response was observed when both were applied. The N 30 P 80 treatment made a "profit" of $10.26 per acre from a $12 per acre fer- tilizer treatment. [28] EFFECTS OF FERTILIZATION ON GRAIN QUALITY The factors defining quality in cereal grains vary, depending on how the grains are to be used. Most California grain is used for feeding livestock and poultry. A lesser proportion is used for direct human consumption, primarily in flour, breakfast cereals, malt products, and beer. Only some of the general aspects of grain quality will be considered in this discussion. Test Weight of Grain Test weight per bushel is an important quality factor in assigning a grade to a given lot of grain under official grain standards of the United States. Test weight is the weight of the volume of grain required to fill a standard bushel measure. The test weight per bushel of barley is related to the total digestible nutrients in the grain. Low test weight barley is bulkier, has a higher fiber content, and is therefore lower in total digestible nu- trients than is barley weighing the stand- ard 48 pounds per bushel. The test weight of barley is a part of the official grade designation and helps determine market value. Maltsters prefer a plump barley with test weight of 46 to 50 pounds per bushel for six-row barley, and 50 to 52 pounds for two-row barley such as Hannchen. Test weight measurements were made on barley samples taken from fertilizer tests in 1947 and 1948 to determine to what extent test weight of barley was in- fluenced by nitrogen and phosphorus application. Considerable variations in test weight were encountered. These were affected by variety and climatic condi- tions, as well as by fertility. The effect of nitrogen fertilizer on the test weight of barley is closely related to soil moisture supply as shown in table 10. With irrigated barley, adequately sup- plied with moisture, nitrogen alone or with phosphorus had no effect on test weight. Barley on fallow-cropped land with adequate soil moisture was likewise unaffected in test weight by nitrogen fer- tilization, although the weight values were somewhat lower than those obtained from irrigated barley. Under conditions of spring drought, the use of nitrogen on soils with adequate Table 10. — Effect of Cropping System and Nitrogen and Phosphorus Fertilization on Test Weights of Barley on Soils with Adequate Phosphorus Cropping conditions Test weights of barley with nitrogen applied at: No Nl5 N M N« Irrigated barley (adequate moisture) : N alone lb/bu 50.8 50.8 46.3 45.9 45.3 45.7 lb/bu 51.0 51.5 46.3 46.2 44.4 44.2 lb bu 51.2 52.0 46.0 46.5 44.7 44.6 lb bu 51.5 N +P 80 51.4 Fallow-cropped barley (adequate moisture) : N alone 46.2 N +P 40 46.8 Fallow-cropped barley (spring drought) : N alone 43.6 N +P 40 43.8 [29 Table 11. — Test Weights of Barley Grown on Soils with Acute Phosphorus Deficiency Nitrogen applied Test weights of barley with phosphorus applied at: Po Pio P20 P40 lb/A 10 20 40 lb/bu 45.3 45.3 43.3 42.7 lb/bu 46.9 45.8 44.9 43.6 lb/bu 46.8 46.5 45.4 43.7 lb/bu 47.6 46.4 45.7 44.9 phosphorus tended to reduce the test weight. Under these conditions addition of phosphorus had no effect. Where nitrogen was applied in amounts suffi- cient to cause greatly increased vegeta- tive growth — followed by acute spring drought conditions — both the yield and the test weight of barley were reduced. On soils of acute phosphorus defi- ciency, test weight was increased by phos- phorus fertilization, but was reduced where nitrogen was added. The average test weights of barley harvested from four such locations are shown in table 11. The increases in test weight from use of phosphorus amounted to 4.4 pounds per bushel in some cases, while the reduc- tions in test weight due to nitrogen amounted to as much as 4.5 pounds per bushel under extreme conditions. The in- creases in test weight attributed to phos- phorus are probably related to barley's more extensive root system which enables it to seek moisture at deeper levels. Protein Content of Grain The crude protein (Nx6.25) content of grain may be of importance in deter- mining its value as livestock feed or for use by the malting industry. Data from this study indicate that protein content of wheat and barley may be altered to some degree by fertilization but that it is also affected by variety, climate, and crop- management practices. In general, applications of fertilizer nitrogen increase the protein content when more of this nutrient is taken up than is utilized in the growth needs of the cereal plants. Data from samples taken from barley tests are used in table 12 to illustrate how fertilizer treatments affect the protein content of the harvested grain. The data shown are from individual locations but each figure is representative of a number of areas and conditions. On soils with adequate phosphorus In table 12, case 1 illustrates a situa- tion in which nitrogen was acutely de- ficient. Yields were greatly increased by 15 pounds of nitrogen. Thirty and 45 pounds of nitrogen gave higher yields, but the rate of improvement became pro- gressively less as higher amounts were applied. The per cent protein was not materially affected by the 15- to 30- pound rates of nitrogen. The 45-pound application, which had little effect on yield, clearly increased the protein con- tent. The addition of phosphorus had no effect on yield or protein content. Case 2 shows a condition in which nitrogen was only slightly deficient. Ap- plications of fertilizer nitrogen had only a small effect on yield. Each added incre- ment of nitrogen brought about an addi- tional increase in protein. Here again, phosphorus had no significant effect on yield or per cent protein. Case 3 illustrates how applications of nitrogen made late in the season after yields had already been determined can materially increase the protein content. Foliar sprays applied a week before bloom illustrate the magnitude of pro- tein changes possible. Here protein was increased from 7.3 to 8.5 per cent by sprays of urea which supplied 44 to 66 pounds of nitrogen per acre. Case 4 demonstrates that, where lack of moisture affects crop yields, nitrogen applications may cause a considerable in- crease in protein content of grain. Nitro- gen applications made at planting time [30 Table 12. — Effects of Nitrogen Fertilizers on Yield and Protein Content of Barley on Soils with Adequate Phosphorus Crop and cropping conditions Nitrogen applied Phosphorus applied Yield Protein content Case 1. Rojo Barley, adequate mois- ture, acute nitrogen deficiency (Santa Clara County) lb/A lb/A 40 lb/A 458 570 per cent 7.19 7.38 15 15 40 1,005 940 7.00 7.00 30 30 40 1,260 1,358 7.19 7.43 45 45 40 1,485 1,388 7.88 8.25 Case 2. Tennessee Winter barley, ade- quate moisture, slight nitrogen de- ficiency (Yolo County) 40 1,644 1,674 10.5 10.5 15 15 40 1,828 1,770 11.06 11.31 30 30 40 1,824 1,848 12.31 11.88 45 45 40 1,818 1,908 13.13 13.50 Case 3. Tennessee Winter barley on Yolo loam, late nitrogen applications from foliar urea sprays (Yolo County) 2,523 7.30 22* 2,421 7.95 44* 2,781 8.48 66* 2,643 8.52 Case 4. Tennessee Winter barley, mod- erate nitrogen deficiency followed by late spring drought (Stanislaus County) 40 2,145 2,318 10.88 10.69 15 15 40 1,928 1,725 11.44 11.63 30 30 40 1,553 1,560 13.06 12.69 45 45 40 1,470 1,530 13.06 12.63 From 50, 100, and 150 lb urea/100 gal water applied 1 week before bloom. 31] stimulated additional tillering. Acute spring drought conditions prevailed; the soil moisture was not adequate to permit normal maturation of the increased num- ber of heads. This resulted in reduced yields with shriveled grain higher in pro- tein content and probably lower in starch than grain from unfertilized plants. The addition of phosphorus did not alter the effect of nitrogen on yield or per cent protein. Similar increases in protein con- tent with little or no change in yield may be expected from nitrogen application when drought conditions are less severe. Table 13. — Effects of Fertilizers and Cropping Conditions on Yield and Protein Content of Grains on Phosphorus-Deficient Soils Cropping conditions Nitrogen applied Phosphorus applied Yield Protein content Case 1. Atlas Barley on irrigated land, acute phosphorus deficiency, slight nitrogen deficiency (Merced County) lb/A Case 2. Mahout Barley, slight phospho- rus deficiency, acute nitrogen defici- ency, annual cropping (Napa County) 15 15 15 15 30 30 30 30 45 45 45 45 15 15 15 15 30 30 30 30 45 45 45 45 lb/A 20 40 80 20 40 80 20 40 80 20 40 80 20 40 80 20 40 80 20 40 80 20 40 80 lb/A 1,740 2,618 2,745 2,895 1,975 3,315 3,143 3,030 1,995 3,293 4,090 3,420 1,598 3,773 3,720 3,848 1,395 1,485 1,448 1,448 1,448 1,635 1,628 1,898 1,898 1,980 1,853 2,385 2,160 2,423 2,340 2,813 per cent 10.9 10.0 10.0 9.2 11.8 10.0 10.0 10.1 11.6 10.5 10.1 10.2 13.0 10.4 10.6 10.1 7.8 7.7 7.6 7.7 7.6 7.2 7.1 7.6 7.6 7.6 7.2 7.4 7.8 7.6 7.6 7.8 [32 On phosphorus-deficient soils Both nitrogen and phosphorus may affect, to some degree, protein content of grain grown on soils deficient in phos- phorus. The effects of nitrogen are simi- lar to those observed on soils with ade- quate phosphorus, as described in the preceding section. There were, however, further effects of increased phosphorus supply. In table 13, case 1 shows the effects of phosphorus fertilization on irrigated bar- ley acutely deficient in phosphorus and moderately deficient in nitrogen. Nitro- gen alone had little effect on yield, but Table 13. — (Continued) Cropping conditions Nitrogen applied Phosphorus applied Yield Protein content lb/A lb/A lb/A per cent Case 3. Onas Wheat, acute phosphorus 855 10.6 deficiency, slight nitrogen deficiency, 20 1,298 10.3 fallow cropping, adequate moisture 40 1,260 10.3 (Monterey County) 80 1,470 10.5 15 953 11.8 15 20 1,350 10.8 15 40 1,343 10.9 15 80 1,388 10.4 30 953 12.1 30 20 1,463 11.4 30 40 1,628 10.9 30 80 1,785 10.9 45 998 12.3 45 20 1,538 12.6 45 40 1,710 12.7 45 80 1,613 12.1 Case 4. Arivat Barley, acute phosphorus 908 14.9 deficiency, nitrogen adequate, fallow 20 1,305 14,4 cropping, spring drought (Monterey 40 1,343 15.9 County) 80 1,200 15.4 15 1,073 15.4 15 20 1,260 35.2 15 40 1,178 16.1 15 80 1,275 16.4 30 900 14.9 30 20 1,155 15.2 30 40 1,163 16.4 30 80 983 17.1 45 863 16.1 45 20 1,028 15.7 45 40 1,140 15.6 45 80 1,148 14.5 [33] protein content was increased by nitro- gen applications. The use of phosphorus alone and at each nitrogen level greatly increased yields, which in turn brought about a definite decrease in protein values. None of the combination treat- ments provided enough nitrogen to in- crease the protein content of the grain. Case 2 illustrates conditions on soil acutely deficient in nitrogen and mod- erately responsive to phosphorus. Here nitrogen alone increased yield of barley from 1,395 to 2,160 pounds per acre, with benefit from each increment of ni- trogen. Nitrogen alone had no effect on protein. Phosphorus alone tended to in- crease yield and to depress per cent pro- tein very slightly. Additions of phospho- rus at each nitrogen level increased yields clearly and tended to reduce protein con- tent to a slight extent. Case 3 represents a situation with ade- quate moisture where phosphorus was acutely deficient and nitrogen only slightly deficient after a period of fallow. Yields were not significantly increased by nitrogen alone, since phosphorus lim- ited growth, but protein values were in- creased slightly by each increment of nitrogen. After phosphorus was applied, nitrogen treatments increased yields up to a maximum at 30 pounds nitrogen with no change in per cent protein. The 45 pounds of nitrogen treatment, which caused no further increase in yield, did show higher protein values. Case 4 indicates the effects of phos- phorus on protein values of barley where severe spring drought prevailed. Here the soil was acutely deficient in phospho- rus, but had a fair nitrogen supply after fallow. Applications of nitrogen alone had little effect on yield, but tended to increase protein content. Phosphorus alone, however, increased yields but, be- cause of limited moisture, tended to pro- duce "light grain" of higher protein content. The addition of nitrogen to phos- phorus caused more vegetative growth, tended to reduce yields and to produce grain of higher protein content. This case represents an extreme drought condition. The use of phosphorus on fallow, phos- phorus-deficient lands with limited spring rainfall but with moisture at depth in the soil usually stimulates early growth and deeper rooting, so that well-filled grain is usually produced with little or no change in protein composition. Effect of Fertilization on Malting Quality of Barley Barley must meet exacting quality re- quirements if it is to be used for malting. Six-row varieties, such as Atlas 46 and Tennessee Winter, and the two-row va- riety Hannchen are suitable if they are of proper protein content and have well- filled, plump kernels. The malting process involves steeping, germination, and kilning of the whole grain. Barley grain is composed of two principal parts, the germ, or embryo, which contains most of the protein, and the endosperm, which is composed prin- cipally of starch. During the "sprouting" or restricted germination phase of malt- ing, enzymes are formed or released from inactive forms in the grain. In subsequent uses of malt, the enzymes liquefy the starch of the grain and convert it into soluble, fermentable sugars, which may then either be fermented by yeast to form alcohol or used as such in malt syrups and other food products. The evaluation of barleys for use of the malting or brewing industries in- volves a number of measurements, and preferably includes experimental malting and malt analysis. This brief discussion will be limited primarily to the relation- ship between the protein content of bar- ley and the malt quality factors — per cent malt extract and diastatic power. Malt ex- tract is the percentage of the malt that is made soluble during "mashing" in water, and is related to the amount of beer which may be expected from a sample of barley after malting. Diastatic power, expressed in degrees Lintner (°L), is a [34] measure of the starch-converting power of malt produced from a barley. Relation of per cent protein of barley to per cent malt extract and diastatic power Varieties of barley differ rather widely in extract percentage and diastatic power of malts prepared from them. Within a variety, these two malt factors are closely related to protein content. The relation- ship between per cent protein of Atlas barley and the yield of malt extract, and the diastatic power of its malt are shown in figure 7. It will be noted that malt ex- tract decreased as the protein content became greater. Diastatic power, how- ever, became greater with increasing bar- ley protein values. Effects of fertilizer and soil management on malting characteristics of barley Commercial fertilizers may be ex- pected to influence malting quality when the applied materials cause change in the protein content of the grain. The factors affecting protein content have been dis- cussed in the preceding section. Malting data on Atlas barley samples from the 1950 Merced County test illustrate (table 14) how fertilizer treatments which alter yield and protein content of grain also affect diastatic power and per cent malt extract. At this location, phosphorus was acutely deficient. Because of this defi- ciency, nitrogen alone had no effect on Malt Extract RELATION OF PER CENT PROTEIN OF BARLEY TO Diastatic Power 10 II 12 Per Cent Protein in ATLAS Barley Fig. 7. Malt extract (black dots) decreased with increased protein content of barley, but diastatic power (circles) became greater with higher protein values. [35 Table 14. — Effect of Fertilizer on Yield and Malting Quality of Atlas Barley (Merced County, 1 950) Fertilizer treatment Yield Protein content Dia- static power °L 62 65 49 55 Malt extract None . . . N 45 *80 N45P8C. lb/A 1,740 1,598 2,896 3,820 per cent 10.8 13.0 9.3 10.1 per cent 74.2 72.1 76.4 74.0 yield but did increase the protein content of the grain. Diastatic power was in- creased and yield of malt extract was reduced in proportion to change in protein. Application of phosphorus alone in- creased yields. Here the protein content was reduced since the nitrogen supply from the soil had to be distributed among the larger number of barley grains con- stituting the 66 per cent yield increase. Diastatic power was materially reduced as was per cent protein, while per cent malt extract was increased. Where both nitrogen and phosphorus were applied, the malt extract and pro- tein values remained unchanged. In this case the added nitrogen that increased yield was only sufficient to maintain the protein content of the larger barley crop resulting from nitrogen and phosphorus treatment. It is to be expected that malting quality as measured by per cent malt extract will be reduced when nitrogen applications are materially greater than needed to take care of increased yield caused by fertilization. Rates of nitrogen that in- crease yield but do not alter protein con- tent appreciably will have little or no effect on malting quality. Usually the de- sirable rates of nitrogen application for production of malting barley will be those which give slightly less than maxi- mum yield. Higher nitrogen applications may be expected to increase protein con- tent and reduce malting quality. It is important to recognize that nitro- gen supply in relation to growth is more important than the actual amount of fer- tilizer currently applied. When barley follows a heavily fertilized vegetable or field crop or a legume crop whose residue increases the soil nitrogen supply, we may expect barley of higher than usual protein and reduced malting quality. Similarly, midseason irrigations, which increase nitrification of organic nitrogen in a peat or muck soil, may increase the supply of nitrates and have the same effect in increasing protein as would a late application of commercial fertilizer. LITERATURE CITED Bingham, F. T. 1949. Soil test for phosphate. California Agriculture 3 (8) : 11. Jenny, H., J. Vlamis, and W. E. Martin 4 1950. Greenhouse assay of fertility of California soils. Hilgardia 20 (1) : 1-8. Olsen, S. R., et al. 1954. Estimation of available phosphorus in soils extracted with sodium bicarbonate. U. S. Dept. Agr. Cir. 939. . Storie, R. Earl, and Walter W. Weir 1953. Soil series of California. (Litho.). Associated Students' Store, University of California, ,-* Berkeley. 10m-ll,'60(B1367)LL [36] .2 O 'J£~ "5 M c 4- v> O « (A E < o s p si o ^5 H < < «s o i fl {fl OS* © .5 d S ^ s^fs M o ? >> ^ g oj ^ d p<' k4 h 6 M w Id i £ « ^s ©".3.3 © >>"3 S m £ £ pq E g w Q © © • fi "S q sgafSS S3 .- " ^ - O H Ah* PQ 03 Pk ^ W O h^ h4 ^ > I © w w SSI ofi" Pn'dS >*«Q G £ P d O © C J3 03p3&h"^ CO i-H CO -NH rj< (N • "^ tH OOMWMMWH^ • CO CO ">tf CN Ci CN CO • t> CN CO CN CO -^ CO CN N^W00i>tf)(NMe0Me0MM^^OHin(N(NH00Oin05C0Ot-M«0^ □ K f-i n5 O g3 Q , _ s ?>5 Table 2A. — Relation of Soil Profile Group and Soil Series to Response of Grain to Nitrogen and Phosphorus Fertilizers Soil series No. of observed responses to fertilizers None N only P only NP Group I — Recent alluvial soils 1. Cajon 2. Columbia 3. Corralitos 4. Cortina 5. Dublin 6. Elder 7. Egbert 8. Foster 9. Hanford 10. Hesperia 11. Holtville 12. Panoche 13. Ryde 14. Surprise 15. Sycamore 16. "Tulelake Muck' 17. Vina 18. Yolo Total 14 17 Group II — Young alluvial soils 1. Arbuckle. . . 2. Chino 3. Esparto 4. Exeter 5. Greenfield. 6. Imperial. . . 7. Sacramento 8. Temple 9. Tulare Total 6 11 Group III — Old alluvial soils 1. Adelanto 1 1 1 3 3 1 2 3 1 1 2 1 2 1 2 1 2 1 1 1 2 - 1 2. Chualar 1 3. Ducor 3 L L 2 4. Gridley 2 5. Harrington 3 6. Lockwood 3 7. Montezuma 2 8. Myers 3 9. Ojai 1 10. Orestimba 1 11. Pleasanton 2 12. Ramona 7 13. Rincon 14. Tehama 4 4 Total 10 15 8 3 36 [38] Table 2A. — (Continued) Soil series No. of observed responses to fertilizers None N only P only NP Total Group IV — Claypan soils 1. Cachuma. . 2. Cometa. . . . 3. Coombs. . . 4. Corning. . . . 5. Hartley 6. Hillgate 7. Huerhuero 8. Kimball. . . 9. Merriam. . . 10. Olivenhain. 11. Placentia. . 12. Standish... 13. Watsonville 1 1 1 1 1 3 4 1 1 1 4 5 1 1 1 1 1 1 1 2 1 1 2 Total 12 25 1 Group V — Hardpan soils 1. Fresno 2. Hames 3. Lewis 4. Madera 5. Monserate 6. Montague 1 1 1 1 1 2 1 1 6 1 1 2 4 4 3 2 2 1 1 2 1 7. Redding 5 8. Rocklin 5 9. San Joaquin 10 10. Stockton 1 Total 3 2 10 15 30 Groups VII, VIII, IX — Upland soils developed in place 1. Altamont* 2. Diablo 1 1 1 1 1 2 1 2 1 1 1 3 1 1 3 2 6 2 3. Holland 2 4. Linne 5 5. Los Osos 2 6. Olympic 1 7. Sierra 2 8. Sites 1 9. Vista 1 10. Whitney 1 Total 1 4 8 10 23 * Includes some soils formed on soft stratified materials and mapped as Altamont in older soil surveys, tentatively reclassified as Cometa- Whitney Complex. T39 1 PURPOSES OF A UNIVERSITY. ...#o explore ..see new vista: ind new riches "I like to compare scientific research to mountain climbing in an unexplored range. Considerable preparation, training, and a strong motivation are required to get up to the upper altitudes even if no one particular stretch of the way is particularly difficult. But once there, it is relatively easy for one to see vistas or even to stumble across new riches that people of equivalent ability who have stayed behind, have no, possibility to see or to find." Glenn T. Seaborg Nobel Laureate in Chemistry, 1951 (From his address at the Secondary Education Board Conference, 'San Francisco, April 5, 1957)