UNIVERSITY OF CALIFORNIA PUBLICATIONS COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA A Progress Report upon Soil and Climatic Factors Influencing the Composition of Wheat By G. W. SHAW and E. H. WALTERS fc: C«CCK PLAT 0/iDi3TUHTitD \u S' H*J «+•«• »4«S ■+► 5 1 •+* 5 •• 30IL CALIT MO SO.c Pla^ Or A 5oil Lxcma/igl. Lkplkimlht BULLETIN No. 216 (Berkeley, Cal., June, 1911) W. W. SHANNON SACRAMENTO - - SUPERINTENDENT OF STATE PRINTING 1911 EXPERIMENT STATION STAFF. E. J. Wickson, M.A., Director and Horticulturist. E. W. Hilgard, Ph.D., LL.D., Chemist (Emeritus). W. A. Setchell, Ph.D., Botanist. Leroy Anderson, Ph.D., Dairy Industry and Superintendent University Farm Schools. M. E. Jaffa, M.S., Nutrition Expert, in charge of the Poultry Station. R. H. Loughridge, Ph.D., Soil Chemist and Physicist (Emeritus). C. W. Woodworth, M.S., Entomologist. Ralph E. Smith, B.S., Plant Pathologist and Superintendent of Southern California Pathological Laboratory and Experiment Station. G. W. Shaw, M.A., Ph.D., Experimental Agronomist and Agricultural Technologist, in charge of Cereal Stations. E. W. Major, B.Agr., Animal Industry, Farm Manager, University Farm, Davis. F. T. Bioletti, M.S., Viticulturist. B. A. Etcheverrt, B.S., Irrigation Expert. George E. Colby, M.S., Chemist (Fruits, Waters, and Insecticides), in charge of Chemical Laboratory. H. J. Quatle, A.B., Assistant Entomologist, Plant Disease Laboratory, Whittier. W. T. Clarke, B.S., Assistant Horticulturist and Superintendent of University Exten- sion in Agriculture. H. M. Hall, Ph.D., Assistant Botanist. C M. Haring, D.V.M., Assistant Veterinarian and Bacteriologist. John S. Burd, B.S., Chemist, in charge of Fertilizer Control. E. B. Babcock, B.S., Assistant in Agricultural Education. W. B. Herms, M.A., Assistant Entomologist. J. H. Norton, M.S., Assistant Chemist, in charge of Citrus Experiment Station, River- side. W. T. Horne, B.S., Assistant Plant Pathologist. J. E. Coit, Ph.D., Assistant Pomologist, Plant Disease Laboratory, Whittier. C. B. Lipman, Ph.D., Soil Chemist and Bacteriologist. R. E. Mansell, Assistant in Horticulture, in charge of Central Station grounds. A. J. Gaumnitz, M.S., Assistant in Cereal Investigations, University Farm, Davis. E. H. Hagemann, Assistant in Dairying, Davis. B. S. Brown, B.S.A., Assistant in Horticulture, University Farm, Davis. F. D. Hawk, B.S.A., Assistant in Animal Industry. J. I. Thompson, B.S., Assistant in Animal Industry, Davis. R. M. Roberts, B.S.A., Field Assistant in Viticulture, University Farm, Davis. J. C. Bridwell, B.S., Assistant Entomologist. C. H. McCharles, B.S., Assistant in Agricultural Chemical Laboratory. N. D. Ingham, B.S., Assistant in Sylviculture, Santa Monica. E. H. Smith, M.S., Assistant Plant Pathologist. T. F. Hunt, B.S., Assistant Plant Pathologist. C O. Smith, M.S., Assistant Plant Pathologist, Plant Disease Laboratory, Whittier. F. L. Yeaw, B.S., Assistant Plant Pathologist, Vacaville. F. E. Johnson, B.L., M.S., Assistant in Soil Laboratory. Charles Fuchs, Curator Entomological Museum. P. L. Hibbard, B.S., Assistant in Fertilizer Control Laboratory. L. M. Davis, B.S., Assistant in Dairy Husbandry, University Farm, Davis. L I Bonnet, LA., Assistant in Viticulture. s. s. Rogers, B.S., Assistant Plant Pathologist, Plant Disease Laboratory, Whittier. B. A. Madson, B.S.A., Assistant in Cereal Laboratory. Walter E. Packard, M.S., Field Assistant, Imperial Valley Investigation, El Centre M. E. Stover, B.S., Assistant in Agricultural Chemical Laboratory. P. L. McCreary, B.S., Laboratory Assistant in Fertilizer Control. E. E. Thomas, B.S., Assistant Chemist, Plant Disease Laboratory, Whittier. Anna Hamilton, Assistant in Entomology. Mrs. V). L. Bunnell, Secretary to Director. \\\ II. Volck, Field Assistant in Entomology, Watsonville. B. I>. Morris, B.S., Field Assistant in Entomology, San Jose. HUNTER, Field Assistant in Entomology, San Mateo, .j. c, Roper, Patron, University Forestry Station, Chico. J. T. BEAkss, Foreman, Kearney Park Station, Fresno. Miller, Foreman, Forestry Station, Chico. A PROGRESS REPORT UPON SOIL AND CLIMATIC FACTORS INFLUENCING THE COMPOSITION OE WHEAT. By G. W. Shaw and E. H. Walters!* For many years the effect of environment upon the composition of grain has been the subject of much study by numerous investigators. The results of these investigations have been quite contradictory, and have resulted in a very wide divergence of opinion as to the factors which influence the gluten content of wheat. In practically all of these studies, the plan has been to transfer the seed from one point to another and grow it under a variety of conditions, and from the results so obtained attempt to draw conclusions as to the influence of environment upon the composition of the grain. In summarizing the reports of previous investigators in this field one notices that no experiments have been conducted under conditions which would eliminate all the varying factors, with the exception of the composition of the soil itself. In the experiments here reported, wheat from the same seed was grown under the same conditions on soils of widely different origin put under the same field influences, thus establishing the condition referred to above. Many valuable practical results have been obtained from a study of soil fertility in connection w T ith the chemical composition of the crop. But in the attempt to establish a relationship between the chemical composition of the soil and that of the crop grown upon it many diffi- culties arise. Soils contain varying amounts of the elements of plant food. In one soil these constituents may be in a form which can be readily assimilated by plants, while in another soil they may be present in sufficient quantities, but not in accessible forms. The utilization of one ingredient by a plant may be aided or retarded by the presence or absence of other soil ingredients. For example, in discussing the lime content of soils, Hilgard 1 shows that low percentages of phosphoric acid. nitrogen, and potash in the soil prove adequate in the presence of high amounts of lime. The physical and biological conditions of the soil, and the variations in climate and soil moisture, may also influence the assimilation of the plant food contained in the soil. With such com- plexities, the attempt to draw any definite conclusions from the results of a single investigation would be to depart from the correct scientific method. * Note. — The bibliography of this paper and the chemical work relating to the second series of plats was done by Mr. Walters as a portion of his work for masters degree. The work relating to the first series of plats was done by the regular station officers. a Hilgard's "Soils," p. 365. 550 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. This study is considered in two parts. Part one is historical, and an attempt is made to bring together some of the most important results of previous investigations already published. The literature devoted to this subject is voluminous, and this paper by no means attempts to quote from all of them. The writers believe, however, that it fairly represents the work relating to the particular phase of the subject dis- cussed herein. Part two is devoted to the experimental phase of the study, the exact nature of which will be discussed in its proper place. PREVIOUS RESEARCHES. Plants are so sensitive to a change of environment that it is difficult to say which of the environmental factors have the greatest influence. Many investigators seem to think that the climate has the greatest effect upon the composition of the crop. Others believe that the soil has the greatest influence. It is a well known fact that true varieties, when grown in the same environment, have a tendency to produce a like product regardless of the original soil. 2 In 1882, Richardson" commenced a study of the influence of environ- ment on cereals, which consisted in growing crops from seeds of the same kind and of known composition in different localities. His results show that seeds of different varieties of wheat when grown in Colorado produced a crop which contained a higher protein and a lower carbo- hydrate content than the original seed. He also observed that the same seed, when grown in California, Oregon, and North Carolina, produced crops with a lower percentage of carbohydrates than the original seed. He concluded from the data obtained that the soil played the most important part in producing these changes. Wiley, 4 in an article discussing the work of Richardson and reporting the work of later experiments, arrives at a different conclusion and states that the soil has the least effect of the environmental factors, provided, of course, that it contains the proper amounts of plant food, but that the length of the growing season is the most effective factor. In 1884, Lawes and Gilbert 5 showed that a wider variation occurred in the potash and phosphoric acid content of the ash of wheat with the same manure in different seasons than under three very different con- ditions of manuring. This point is brought out very clearly in Table I, which is taken from their report. 2 LeClerc, Bui. 128, Bureau of Chemistry, U. S. Dept. of Agr., Indiana Sta. Bui. 61, p. 60. "Buls. 1,4, and 9, Bureau of Chemistry, U. S. Dept. of Agr. 'Yearbook, U. S. Dept. of Agr. 1901, p. 299. s Jour. Chem. Soc.. London. L884, XLV, p. 304. Bulletin 216] FACTORS INFLUENCING WHEAT COMPOSITION. 551 TABLE I. Highest, lowest, and mean percentage of potash, and phosphoric acid in the pure ash in sixteen consecutive seasons. Plot. Fertilizers. Per cent in dry matter of grain Highest. Lowest. Mean. 2 3 10a 2 3 10a Potash. Farmyard manure Unmanured Ammonium salts, alone Phosphoric acid Farmyard manure Unmanured Ammonium salts, alone 0.779 0.838 0.738 1.110 1.075 1.003 0.538 0.601 0.515 0.965 0.898 0.718 0.635 0.662 0.602 1.044 1.003 0.854 Considering the weight per bushel as the single factor in determining the quality of the crop, the same authors observed that the best crops are associated with low percentages of total mineral constituents (ash) and a low percentage of nitrogen in the dry substance. Accordingly, grain of high quality is associated with a high percentage of carbo- hydrates. In every case the lowest weight per bushel was associated with the lowest yield. Table II expresses some of their results. TABLE II. Maximum, minimum, and mean yields of each plot during sixteen years with centage composition of the crop. the per- Percentage composition in dry matter of grain. Weight per bushel. Pounds grain per acre. Plot. Ash. Nitrogen. I Phos- phoric acid. Sul- phuric acid. Lime. Magnesia. Potash. 2 2 Mean 63.8 51.1 57.4 2068 1120 1967 1.93 2.20 2.06 1.58 1.76 1.96 0.97 1.03 1.07 .029 .052 .014 .049 .057 .054 .203 .223 .229 .637 .779 .640 3 3 Mean 62.7 45.9 54.3 1127 359 823 1.95 2.36 2.08 1.65 2.09 1.98 1.00 1.08 1.04 .013 .057 .029 .052 .073 .058 .212 .243 .217 .628 .838 .670 10a 10a Mean 62.6 48.6 53.7 2587 642 1147 1.56 1.98 1.91 1.70 2.43 2.25 0.72 0.88 0.90 .037 .049 .039 .060 .074 .068 .175 .185 .205 .537 .709 .632 A study of Table II will show that in every case the ratio of nitrogen to phosphoric acid is greater in the crop of minimum yield, viz., an increase in the yield is associated with a decrease in the ratio of nitrogen to phosphoric acid. In the crop of minimum yield the percentage of ash, and therefore ash constituents, was higher than in the largest crop. The results of grain grown on plots receiving very different manures but all under the same seasonal conditions are expressed in the following table : 552 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION. TABLFJ III. Analysis of wheat grown on plots receiving different manures. Percentage composition of dry matter in grain. Weight rounds dry Plot per matter Phos- Sul- bushel. per acre. Ash. Nitrogen. phoric acid. phuric acid. Lime. Magnesia. Potash. 2 60.6 1963 1.96 1.80 1.038 .011 .050 .228 .593 3 58.5 836 2.01 1.85 1.035 .017 .054 .219 .630 5a 59.6 975 2.02 1.74 1.051 .013 .056 .222 .635 10a 58.4 1443 1.75 2.08 0.846 .031 .066 .199 .565 11a 59.0 1773 1.85 1.92 0.944 .020 .071 .205 .568 12a 60.1 2014 1.86 1.83 0.947 .019 .059 .203 .596 13a 60.2 1963 1.86 1.85 j 0.952 .015 .054 .203 .601 14a 60.0 2028 1.85 1.87 ; 0.952 .018 .054 .209 .585 7a 59.6 2062 1.8S 1.87 0.962 .010 .052 .218 .599 The different plots were fertilized as follows : 2. Farmyard manure. 3. Unmanured. 5a. Mixed mineral manures. 10a. Ammonium salts. 11a. Ammonium salts and superphosphate of lime. 12a. Ammonium salts, superphosphate and sulphate of soda. 13a. Ammonium salts, superphosphate and sulphate of potash. 14a. Ammonium salts, superphosphate and sulphate of magnesium. la. Mixed mineral manures and ammonium salts. It will be noticed that with one exception, plot 5a, the nitrogen content is fairly uniform. Plot 5a received mineral manures alone and was deficient in nitrogen. On plot 10a, which received ammonium salts, and, therefore, an abundant supply of nitrogen, the nitrogen content was high and mineral constituents low. It will also be seen that the crop grown on plot 11a, which received applications of lime, contained a higher lime content than the crop grown on any of the other plots. On a whole the ash constituents show a marked uniformity. It appears, however, that they are directly influenced by their supply or exhaustion in the soil. On a close study of their results the composition of the crop seems to reflect that of the soil. Yon Liebenberg and E. Von Proskowetz in 1893 found from fertilizer experiments in connection with the chemical analysis of the soil that the yield depends, not only upon an adequate supply of plant food in the soil, but upon the relation of nitrogen to phosphoric acid, the yield being higher the greater the proportion of nitrogen present. Their results show that the ratio of nitrogen to phosphoric acid is greater in the crop than in the soil, and that the supply of nitrogen in the soil is drawn upon much more largely than that of phosphoric acid. Schindler 7 stated that the composition of the grain depends upon the fertility of the soil. Also, that a long growing period from the time of bloom to ripeness caused a low percentage of nitrogen in wheat, that the p Sta. Rec. (1893) Vol. V., p. 702; Abst. Ceiltralb. 56 (1893). p. 345; Abst. Der Weisen, Berlin. BULLETIN 216] FACTORS INFLUENCING WHEAT COMPOSITION. 553 weight of the grain is affected by climate, and that the relation between the protein and carbohydrates is affected by the length of the growing period. Cross and Smith 8 concluded from their investigations of the chemical history of the barley plant that the condition of soil nutrition had little influence upon the composition of the plant. "The plant, in other words, is, as regards soil nutrition, constant or invariable in respect to the relation of its products to assimilation." In 1895 Januszowski 9 from experiments planned to determine the value of the plant analysis in estimating the quality of soil, found the results misleading, since a low phosphoric acid content, for instance, may be due not to the deficiency of that ingredient in the soil but to an excess of potash or nitrogen. He found that the application of phosphoric acid to a soil deficient in that element was followed by an increase in phos- phoric acid in the grain grown on the soil, provided the application of phosphoric acid was not accompanied by liberal manuring with nitrogen. Liebscher and Edler 10 noticed that the application of nitrogenous fertilizers increased the nitrogen content of oats, and that the exclusive application of potash caused a decrease in nitrogen and an increase in potash in the plant. With a complete fertilizer, the percentage of potash was lowest. In studying the effect of humus on the percentage of nitrogen in oats, Wiley 11 conducted pot experiments which consisted in growing oats in peaty soil without manures and with various manures. The soil con- tained on the average less than 10 per cent of mineral matter, about 2.5 per cent of nitrogen, and very little potash and phosphoric acid. The crop was very high in nitrogen, of which much was present as amid nitrogen due to direct absorption from the soil. The protein nitrogen remained within the limits of the usual amounts obtained in ordinary soil. Potash and nitrogenous manures in the amounts applied had no effect upon the yield. Phosphates increased the yield and lowered the percentage of nitrogen, probably due to increased crop. Von Seelhorst and Panaotovie 12 in 1889 observed that the nitrogen and ash constituents of cereals increased with an increase in space between the plants. In other words, within certain limits the nitrogen and mineral constituents in cereals vary directly as the feeding surface of the plants. Bogdan 13 found that the increase of the salt content of alkali soils caused an increase in the nitrogen and ash contents of the grain grown 8 Chem. News, 72 (1895) No. 1883, p. 307. 9 Bied. Centr., 1895, vol. 28, p. 27. "Jour. Larrdw., 1896, p. 84. "Landw. Versuchs. Stats. 1897, vol. 49, p. 193. 12 Jour. Landswirtschaft, 1899, vol. 47, p. 379. 13 Exp. Sta. Rec. (1902) XIII, p. 329. 554 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. therein due to the fact that the absolute weight of the grain diminished. This, he says, explains the high protein content of wheat from the east and southeast of Russia, where the soils are rich in nitrates and other soluble salts. Godlewski 14 in 1901 observed that in the case of potatoes the insuffi- ciency of potash in soil narrowed the ratio of potash to phosphoric acid and of potash to nitrogen in the tubers. The inadequate supply of nitrogen caused the widening of the ratio of potash to nitrogen and narrowed the ratio of nitrogen to nearly all ash constituents. A low nitrogen content of the soil narrowed the ratio of nitrogen to phosphoric acid in barley straw without affecting the relation of the nitrogen to the other elements, while an insufficient amount of phosphoric acid widened the ratio to 5.1, and is considered as indicating lack of phosphoric acid in the soil. An adequate supply of potash in the soil reduced the potash content of barley straw to less than 1 per cent in the dry matter, increased the amount of nitrogen, lime, and magnesia, and narrowed the ratio of potash and phosphoric acid to magnesia. The normal relation of potash, nitrogen, phosphoric acid, lime, and magnesia in barley straw is given at 100, 50, 30, 40, and 10. The author showed that plants growing in a soil deficient in available plant food of any kind will, in their ash, show a corresponding deficiency, or at least a minimum pro- portion of the same ; and that in many cases the nature of the deficiency manifests itself in the form or development of the plant so nearly as to render chemical analysis unnecessary. In 1901, Tollens 15 stated that no definite relation existed between the chemical composition of the ash of plants and the soil in which they were grown. The stage of growth, the available moisture, the thickness of the stand, the soil, and the fertilizers, are all important factors in pro- ducing the variations in the composition of the ash of plants. Wilfarth and Gcell 16 found that increasing amounts of potash in the soil produced corresponding increased amounts of that ingredient in the plant. Whitson, Wells, and Vivian, 17 in studying the influence of soil on the protein content of crops, conducted field and pot experiments with corn, oats, barley, rape, and cowpeas. The crops were grown on soils of different degrees of fertility, and nitrogen determinations were made at frequent intervals in the soil and in the crops. In one instance, the nitrogen content of oats grown on soils having the same physical compo- sition, but different degrees of richness in nitrates, was 1.93 per cent on the poorest soil, 2.53 per cent on the medium soil, and 2.66 per cent on "Exp. Sta. Rec. (1902) XIII, p. 637; Abst. 16 Exp. Sta. Rec. (1901) XII. pp. 207 and 305. 16 Exp. Sta. Rec. (1902) XIII. p. 1030; Abst. l7 Wis. Exp. Sta. Report, 1902, p. 192. Bulletin 216] FACTORS INFLUENCING WHEAT COMPOSITION. 555 the richest soil. In a similar test with corn, the figures were 1.35, 1.59, and 1.80, respectively. The results of the experiments, as a whole, indicated that crops vary greatly in their nitrogen contents at the same stage of development, and that this variation may exist even when crops are making practically equal growth. Under similar seasonal conditions the amount of nitrates in the soil is believed to be the most important factor in causing this variation. The results show a marked relation between the amount of available nitrogen in the soil and the nitrogen content of the plant. The data collected indicated that the richness of the soil determines the yield more than does the climate. The latter determines the length of the growing period and the immunity from early or late frosts and the possibility of bringing the plant to maturity. Wilfarth and Wimmer 18 observed that a deficiency of nitrogen in the soil caused an increase in the percentage composition of carbohydrates, and a decrease with a deficiency of phosphoric acid. Soule and Vanatter 19 stated that a rich soil, or the use of fertilizers, did not seem to increase the protein content of wheat to any appreciable extent. Stahl-Schroder 20 found, from a series of experiments with oats on heavy and light soils with different fertilizers^ that the composition of the seed varies considerably with the season and with the character of the soils, but is not appreciably affected by the variety, or time of planting. He concluded that the analysis of the seeds as a means of determining the assimilable food in soils gives results which are of local value only. Hall 21 states that the soil is the least effective environmental factor in producing variations in the composition of wheat, this statement being based upon data obtained from experiments with oats grown in pots containing six soils of very different characters, which showed that no strict agreement existed between the composition of the ash of the plants and of the soil. The variations in the composition of crops grown in duplicate pots of the same soil were very often greater than between those grown on different soils. Von Seelhorst and Fresenius 22 observed, from experiments with oats, that the nitrogen content of oat straw was decreased when the amount of moisture applied to the plants was increased. In 1902, Widtsoe 23 showed that the. protein content of wheat increased very markedly as the amount of water applied to the soil decreases. The soil that received 30 inches of water produced wheat containing 18 Jour. Landw. 51 (1903), p. 129. 19 Tenn. Sta. Bui. (1903), XVI, No. 4. ^Jour. Landw. 52 (1904), 31. 21 Jour. Soc. of Arts. 1904, 52 ; No. 2711, 881. -Jour. Landw.. 1905. vol. 53, p. 27. "Utah Sta. Bui. 80 (1902), 148. 556 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION. 15.26 per cent of protein ; while the wheat produced on soil that received 7.7 inches contained 26.72 per cent. This difference between the wheat grown on non-irrigated land and on land that received, 13.79 inches of water was 2.82 per cent. In 1906, Le Clerc 24 published that the protein content of wheat grown on arid land was higher than when grown on irrigated land. The protein content of wheat, expressed in per cent, grown on irrigated and on adjoining non-irrigated land was 11.1 and 17.7, respectively. Pingree 25 in studying the effect of various fertilizers upon the com- position of oats found that where muriate of potash was applied alone and as part of a complete fertilizer a distinct increase of potash was found in the ash of the plant; also, the application of dissolved phos- phate caused an increase of phosphoric acid in the ash of the plant. Snyder 26 showed that by the proper application of fertilizers the quality of wheat could be improved and thus increase the protein con- tent at least 1 per cent. Some of his results are expressed in Table IV. TABLE IV. Protein and ash content of wheat grown on plots receiving different fertilizers. Kind of fertilizers. Nitrogen Potash Phosphoric acid Complete (N, K 2 0, P 2 5 ) No fertilizer Number of Protein samples. Nx6.25. 12 13.63 12 13.02 12 12.65 12 13.17 12 13.04 Ash. 1.58 1.62 1.73 1.69 1.64 It will be noticed that the protein content was highest in the wheat grown on plots receiving a nitrogenous fertilizer, and lowest on plots fertilized only with phosphoric acid. Stewart and Greaves 27 found that the ash of plants grown in Utah is high, due to the richness of the soil in mineral constituents ; and that the nitrogen content of wheat grown on arid land is higher than that of wheat grown on irrigated land, which is in accord with the facts observed by Le Clerc. "Yearbook 1906, U. S. Dept. of Agr., 199. 25 Penn. State College Report, 1906, 43. 26 Jour. Am. Chem. Society, 1908, 30: 1, 604. "Utah Sta. Bui. 103 (1908). BULLETIN 216] FACTORS INFLUENCING WHEAT COMPOSITION. 557 EXPERIMENTAL DATA. In 1905, the California Experiment Station, in collaboration with the Bureau of Plant Industry of the United States Department of Agri- culture, undertook an investigation along a similar line, which consisted in growing wheat from the same original seed continuously in each of three localities, viz.: (1) Kansas, Texas, and California; (2) in South Dakota, Kansas, and California. The crop from the apex of each of these two triangles was sent to each of the other two stations of the same triangle and there grown under the same conditions as the continuously grown seed. Thus, at each station there were three plats all from the same original seed, the seed of the other two plats coming from the other points of the triangle. Two varieties of wheat were thus grown, viz.: Crimean, C. I., 1437 (?), a common wheat of the winter type ; and Kubanka, C. I., 1440, a durum variety. The former was grown in California. Kansas, and Texas, the original seed having been grown in Kansas in 1905 ; the latter in Cali- fornia, Kansas, and South Dakota, the original seed having been grown in South Dakota in 1905. These plantings have been continued until the present year. Samples were taken each year and analyses made, the detailed analyses as made by Dr. J. A. LeClerc, of the Bureau of Chemistry, United States Department of Agriculture, have been published in Bulletin 128 of that Bureau. The results obtained from analyses of the same samples made at this station are essentially the same as those published by Dr. Le Clerc, and consequently need not be duplicated in the present paper. The essential conclusions from these analyses are stated by Dr. Le Clerc as follows : (1) "Wheats of the same variety when grown in the same locality and under the same conditions are, therefore, seen to vary but little in composition, although coming from seed differing widely in physical and chemical characteristics. These results are corroborative of Ecken- brecher's work with barley, and are entirely at variance with Hall's statement that 'each race or variety possesses qualities which are modi- lied only to a slight degree by seed, soil, or climate. ' ' ' (2) "Wheat of any one variety, from any one source, and absolutely alike in chemical and physical characteristics, when grow T n in different localities, possessing different climatic conditions, yields crops of very widely different appearance and very different in chemical composi- tion/' (3) "The results so far obtained would seem to indicate that the soil 558 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. and seed play a relatively small part in influencing the composition of crops. While the above results seem to indicate that the climatic factor is the principal, if not the only one, affecting the nitrogen content of wheat, yet the experiment was subject to the same sources of error and elements of doubt, as all of the other trials where seed transference had been practiced in the prosecution of studies of this problem, viz., a change of both soil and climate at the same time, thus giving two variable factors, both climate and soil. In 1907, the senior author undertook to neutralize the effect of one of these factors, viz., climate, by securing from Hays, Kansas, a sufficient amount of soil, known to have produced for a number of years high gluten wheat, to make a plat 6 feet long, 3 feet wide, and 3 feet deep. That this Kansas soil was capable of producing a high gluten wheat is evidenced by the protein content of the wheat grown upon it the previous season and forwarded together with the soil. This wheat showed a protein content of 20.06 per cent, as indicated in the table below. The soil was removed from its original position in the ground in six- inch layers which were shipped in bags to the University Farm at Davis, California, where it was placed in a hole previously prepared to receive it, the soil being placed in said hole in the sequence indicated by the labels, thus bringing the original bottom soil in the corresponding position to that occupied in Kansas, and the same for each other six- inch layer. A second plat was prepared in a similar manner alongside of it by removing the soil from a like area and to the same depth, and replacing the same soil in the hole whence it had been removed. Each of the holes previous to refilling was lined by a rather loose cement lining 1J inches thick, except the bottom, which was left without lining, the object being to prevent the roots from passing beyond their own area of soil laterally. In placing the soil in the holes, it was dry-tamped to settle it as much as possible, and thus it was allowed to remain until the rain had settled it, after which each plat was cultivated and seeded. < )n each of the two plats two types of wheat were grown from 1907 to 1910, inclusive. On one end of each of the plats was placed a high gluten Turkey Red wheat, which grew on the Kansas soil the previous year, and which another table shows carried an unusually high protein content. On the other end of each plat was seeded a low protein Cali- fornia-grown Durum wheat. I >y this soil transfer it was intended to neutralize the effect of climate and hare as a variable factor only the soil, whereas by the seed-transfer method heretofore practiced, there were always two variables and one could never be certain what proportional influence might be due to soil and what to climate in whatever variation occurred in the product. Bulletin 216] FACTORS INFLUENCING WHEAT COMPOSITION. 559 The writer's idea in using both a low-protein and high-protein grain in this experiment was to secure something of a check, believing that if the soil should prove to be the controlling factor, then the high-gluten Kansas wheat would remain high gluten and fall materially lower upon the California soil, and that the low-gluten California would remain practically the same in the California soil plat and show a marked increase in gluten when grown on the Kansas soil under California climate. The results set forth in the table do not show that the soil has produced any marked effect of this kind. The Soils. — The two soils used in this experiment show a marked con- trast in appearance and in texture. The California soil is the type which is quite general in the Sacramento Valley, and known as a gray silt loam. It has been cropped to grain for many years — at least forty — and is still producing under good culture heavy crops. It is quite inclined to bake and crust if wet upon top and then allowed to dry. It is more inclined to do this than is the soil from Kansas. The Kansas soil is black in color, and carries markedly less sand than the California soil, as will be seen from the subjoined mechanical analysis, this difference in sand being compensated by a corresponding increase in silt, while the clay and fine silt content of the two types is essentially the same. This type would undoubtedly be classed as a silt loam, although it exhibits essentially different properties than the California soil. The details of the mechanical analysis are shown in the following table : TABLE V. Mechanical constituents of soils from Davis and Kansas. Diameters of sediments. Pe'centage, Davis. Composition, Kansas. mm. Clay ___ 19.12 40.93 3.35 1.34 7.75 8.78 8.10 3.30 4.15 3.07 18.26 to .016 Fine silt _ .__ 44.56 .016 to .025 .025 to .036 Silt 3.20 11.01 .036 to .047 .047 to .072 .072 to .12 Sand 12.27 7.49 1.19 .12 to .16 .16 to .30 .30 to .50 Summary. Clay .72 .46 .76 99.89 19.12 44.28 17.87 18.62 99.92 18.26 Fine silt 44.7t> Silt 30.77 Sand 3.13 99.89 99.92 560 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION. The chemical composition of the soils as represented by one-foot samples is shown in the following table, the analyses having been made according to so-called official method : TABLE VI. Comparison of soils in soil transference. First foot. Second foot. Third foot. California. ( Kansas. California. 1 Kansas. | California. ! Kansas. Insoluble matter 76.04 Soluble matter 23.96 Iron and alumina _ 15.43 79.79 20.21 10.57 .88 1.22 .22 .66 .15 .30 6.50 76.83 23.17 13.84 1.43 1.74 .27 .49 .08 .32 4.83 80.19 77.80 19.81 22.20 10.67 13.40 .73 .97 2.40 1.58 .44 .25 .75 .45 .05 ; .07 .36 .34 4.47 5.30 79.80 20.20 10.85 1.26 2.25 .33 .87 08 Calcium oxid .85 Magnesium oxid 1 .76 Sodium oxid _ .14 Potassium oxid- .52 Sulfuric acid __ _ ' .13 Phosphoric acid __ .34 .41 411 Volatile matter __ i 5.87 Total soluble matter.-! 24.04 Total nitrogen in soil .100 Humus in soil__ _ _ j 1.54 20.50 .163 1.54 .10 23.00 .085 1.24 .03 19.87 .057 .707 .062 22.36 .058 1.70 .052 20.16 .034 1.12 Nitrogen in humus j .07 .025 In each foot the total soluble matter in the California soil exceeds that of the Kansas soil. The principal difference in the two appears in the iron-alumina content. Jn the top foot, of the essential elements of plant food there appears practically no difference in either lime, potash or phosphoric acid. Both soils appear well supplied with all three of these compounds, and this similarity of composition also extends to the humus, which is identical in amount in the two soils, and to the nitrogen of the humus. The same general relation holds with reference to the soluble portion of the second foot, the California soil showing 23.17 per cent, as against 19.81 per cent for the Kansas soil. The same general difference holds, also, with regard to the iron-alumina content, but in the matter of lime there is a marked increase in the California soil and a slight decrease in the Kansas soil. There is a distinct increase in the second foot of both soils, but no essential change or difference in phosphoric acid content. The humus content quite markedly decreases in both soils, the California soil showing about one sixth less and the Kansas soil less than one half as much. This same difference shows in the total nitrogen in the soil, but the nitrogen in the humus appears to be higher in the Kansas soil which is also true of the first foot of soil. BULLETIN 216] FACTORS INFLUENCING WHEAT COMPOSITION. 561 In the third foot the Kansas soil shows the larger per cent of lime, also of potash and phosphoric acid, while the total nitrogen in the soil still is the higher in the California soil. In both the California and the Kansas soils there appears more humus in the third foot than in the second foot, but there is still less in the Kansas than in the California soil, although the nitrogen in the humus has decreased by about one half and that of the home soil increased. Thus, we may sum up the soil difference as follows : A distinctly larger amount of soluble matter in the California soil ; the top foot in the two soils essentially the same ; in the second foot about twice as much lime in the California as in the Kansas soil ; about two sevenths more potash in the Kansas soil than in the California. The California soil carries a distinctly larger amount of soluble matter, but otherwise is essentially the same, except for total nitrogen, in which the Kansas soil exceeds by about one third. It carries double the lime in the second foot, but not only decreases in amount in the third foot, but falls well below the Kansas soil. It carries less potash, but in phosphoric acid does not differ materially. In total nitrogen it exceeds that of Kansas, as it does in humus content. In the matter of nitrogen the Kansas soil is the better supplied in the top foot, but otherwise the advantage lies with the California soil. Inasmuch as the bulk of the feeding roots of the plant are in the second foot, the California soils seems to have an advantage and this is quite significant when considered with the results obtained from the analysis of the grain grown on these two plots. FIELD NOTES. Field notes and observations for the two seasons here reported were made as follows: 562 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. w 5> f- to CO s 'Tf — gj T-( n ■M S a F-l "~ s a fe s ,Q Fh "3 I g 33 P >> S3 03 03 5 03 S3 •-3 Ha X. ~ ir^ CO rt< lO ?. iC ^_ £ oo C^J t^ - ? Fh 03 >, ~ 0) » ,Q FH -^ ■3 a S3 eS 1 1 S3 S3 § g 00 o I 03 ft S3 Ha Ha Ha rH § t^ CO lO lO -M "^ t^ to OS N CM CO e8 53 Fh "~ M 0) o e! 2 P o >> u S3 a S3 O 03 Q y S3 Ha S ^ i t^ CO CO § Tfi -r OS O C^l CM co -4 Fh " a; > j5 M «1 03 Q © g 03 C3 03 c >> Fh S3 P S3 Ha >> 53 o 03 t^ CO CO 8 o CO t^ CM CM iH lO a Pi , - ( c >> Fh C Fh ~ 2 1 S3 P S Fh >> S3 03 C ^ >. « S3 1-5 03 P 5 •5 t^ CO t^ o rH CO p^ CM e CM CO CM lO jj t» ^ >> o !>S Fh 0) ce Fh 33 op EH .22 5 03 a p Fh .a >> S3 03 >-. >! o a> c o 33 03 Ha Ha ►a t^ CO CO lO OS oo CV ss o3 ® 03 CM t^ O) (M © ■r. h >> Fh *~ ' § R 33 S3 P £j 2 5 Fh >> 03 03 5 ^ a ,Q r*i G S3 Ha 03 33 33 P P ha r^. CO Tj< 8 IS CO ~ CM _ CM tc is g 73 >- Fn >2 r - Fh 33 2 ■r. a P Fh >> 0. i? j3 & >. p fl 1 " 33 03 Ph 33 33 8- p Ha X3 1 33 I S3 i C | 03 ' ■s ! -*-' 1 ■H ! FQ o ! CO I 03 t>J ] +2 6 | ~ 33 i T 03 g 03 S3 s i Fh i p.2 o T3 o a X Fh d 3 03 •M X H O « P s QS ft y,^ Bulletin 210] FACTORS INFLUENCING WHEAT COMPOSITION. 563 OI GO oo ,_! CO ^_ 1^ 3 GO OI | Kansas soil 00 00 p CO i>H CO t— 1 1^. o; tj5 ,_J oi oi l^ >* ^ GO ^4 N - No. 981 B-K O. E 1 d CN ^ ■c S a> -w California soil o OI O CO s -P p CO -r OI s S Iff No. 981 B-C lO oi ^ oi l-^ ^ ^ o; 2 t^ OI — oi © H W Original o CO O -p oi o 1^ -* S3 § oo © No. 981 o OI oi oi oi t^ ^ o o 53 -' — 1 o Kansas soil Oi 3 TJH ©i CO o CO Oi GO oi as id o2 No. 10132 oi 7-1 ©i CO i^ CO C^ 8 i 50 CO ■<* CO *sf o -fl »o OI s o "~2 P3 California soil °i t>- ©1 iC p LO Oi So Q No. 1063 eo " oi CO l>^ CO oi o OI OI si > ^ CO 01 © ©1 © r— 1 00 t^ ^ — Original ««3| O. lO o GO rH l^; ^ O Oi No. 1001 OS oi ©i CO t^ CO ri T-H Oi CO . OI 1 e o ^ r^ lO co o o §» Kansas soil OI Oi Oi C-; o © No. 981 A-K oo oi ^ oi s CD WO ;♦— 1— 1 CO »H i« 8 o California soil Oi OI rt< o o =0* No. 981 A-C 1— I i—i o CD §8 IO ?> CO = CO o £* Q Original to p § Ol g S o o * e C3 No. 981 o OI ©i ©i oi t^ 1-1 1 1-1 ~ r & o to r^ lO CO r^ co CO o Q e& o Kansas soil o «q 10 CO OJ l^; CO t^ e 50 53 1 No. 1073 uo *"• oi CO 1-5 £ Oi GO co w 2 c 3«i " — ^ - to -<*< 00 3 lO S CO 00 OI o o Q3 California soil »H GO OI Oi <© © °3 ^ No. 1072 vi ** ©i CO r ^ CO ^ GO OI CD rr CO "SI OI ' c 3 to ID -H CO s "»* oo Oi "* so ^ ^ Original Lab. lO p 30 "t CC CD «D Ifl *~ § O No. 1071 s " OI SO o, o: CD GO OI ©> i 1 *i e i 1 to i«J • ' § <*— o 1 .* 00 S> i g "^ CD C /. 1 T G, J2 1 i pM "2 , >. -J. " (h — sz. — j o c g GO a D c _£; — c: p 02 OQ P 5c Sc a s __ a rlT ■7. ^ ~ ~ o 'x CO 2 J_! J-, ^ 2 £ X - +J s 4-> *J 5 i~ @ >. r. 33 ._ a p — 53 83 S3 ~ <1 fe Eh ~ X -i soil, undisturbed. CO cm ,_l CM o OS r^ 00 No. 1078 rt 1 ■ ©4 CSS s 85 o OS CO CM 3 ?: Original C. I. No. r^ CM o LO ci e 1571. No. 1074. _ 1-1 o ££ 4 Kl o ^ CO ■* 81 ,_, r^ CO ~ o Tfi t>; ^ i-O Maryland soil. co cm CO r^ CM CO CM No. 1065 1-1 Ci 1 o co S* s? _ & lO Tt< o o o g CO lO ■^ CO lO r^ Ol 8 8 Kansas soil. CN co SS o gB CS No. 1064A 1-1 t^ Ol CO OJ *. *» • 8 o 00 o 8 1*1 o CM g? CO CM CO CO CO CO 8 r* California soil. CO ,_i cm co OS p; Cvl s fl No. 1066A , — < o g CSi S cS to 02 00 Check California CO o CD o 8 CM co o g to soil, undisturbed. No. 1067 id T-t CM co T— ' i «*-» o o CO •2 «<»< CO OD Original C. I. No. CO r4 Si T ~ ) e to ■ka e 5 § o •- a a e C3» 8 V. x i c o S p ■8 65 • q . X X ! +9 s ^o '3 - ~ o m 1 3 q be tx q ca q , o ^ 4J y. c H o CO pj C ■*j 4J Fh A 1 - C, O S o o o CJ o c Eh X 4-1 S3 o X »H (h a < fe &| < X P^ Pi u: s 570 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION. VARIATION IN CHEMICAL COMPOSITION OF GRAIN. The original Crimean seed which had been produced on Kansas soil in Kansas and containing a high nitrogen content, 3.04 per cent, when grown on Kansas soil in California fell to 1.91 per cent, a decrease of 1.13 per cent. The nitrogen content of the same seed remained almost exactly the same when grown on Maryland soil in California, and decreased to 2.4 per cent when grown on California soil in California. In this connection it will be noticed that the nitrogen content of the Kansas soil was the highest, while the Maryland soil contained the least amount of nitrogen. The grain produced on the Maryland soil was pinched and the yield was low, probably due to the inability of that soil to hold moisture. This fact accounts for the high nitrogen content of the grain produced on the Maryland soil. The data shows no regu- larity in the nitrogen content and no relation between the amount of that element in the seed and in the soil. With the exception of the wheat grown on Maryland soil the amount of ash in the grain is fairly uniform. It will also be noticed that the potash and phosphoric acid content of the grain grown on Maryland soil during both seasons was highest, and with one exception, namely, the wheat grown on California soil, the sulphuric acid content was the highest and the phosphoric acid and potash content of the Maryland soil the lowest of the three soils. The lime-magnesia ratio of the Maryland soil is as 1 : 16, and it may be that this large amount of magnesium is responsible for the assimilation of the other constituents to a greater degree. The ash and nitrogen content of the grain grown on both plots of California soil are practically the same, but the variation occurring in the other constituents is almost as great as that occurring in the grain produced on the other soils. This indicates that a disturbance of the soil to a depth lower than the ordinary depth of cultivation has a marked effect on the assimilation by the plant of the mineral elements contained therein. With such a variation occurring in the mineral constituents of the grain grown on the same soil, it would be unsafe to assume that the amount of food ingredients assimilated by the plant is in direct proportion to the available materials present in the soil. The lime content of the Kansas soil was highest and that substance was present in a greater quantity in the grain grown on that soil. The ratio of phosphoric acid to potash is higher in the crop than in the soil. The same fad is also true of the nitrogen-phosphoric acid and nitrogen- potash pal io8. BULLETIN 216] FACTORS INFLUENCING WHEAT COMPOSITION. 571 PHYSICAL APPEARANCE OF GRAIN. A very notable difference occurs in the appearance of the grain. During the first season the grain grown on both plats of California soil, the check plat and the disturbed soil plat, was practically the same, well formed, plump kernels of a typical amber. Very few starchy kernels were noticed in either of the lots. The individual kernels were some- what larger in the grain produced on the check plat, 285 kernels weigh- ing 10 grams, as against 303 kernels from the disturbed soil plat. The seed produced on the Maryland soil was pinched, the grains were much smaller than those mentioned above, 356 weighing 10 grams. A few more starchy grains were observed, although the percentage was below 5 per cent. The results of the second season showed more starchy berries (as high as 8 per cent) in the seed grown on the check plat than that grown on the other California soil plat. And, as in the previous season, the individual kernels were larger, 347 grains weighing 10 grams as com- pared with 374 grains. The seed from the disturbed plat was plump, a typical amber, and has high milling qualities. It contained practically no starchy grains. Again the grain on the Maryland soil was pinched, the berries were small, 474 weighing 10 grams, and practically no starchy grains were present. The seed produced on the Kansas soil contained as high as 60 per cent of starchy grains. The berries were heavier than the others, 300 weighing 10 grams. The original Crimean seed contained no starchy berries, and 335 kernels weighed 10 grams. It is also interesting to note the amount of nitrogen present in the large and small berries. One thousand grains of the seed produced the first season on the check plat, the disturbed plat of California soil, the Maryland soil plat, and the Kansas soil plat weighed 37.4, 34.8, 27.4, and 37.1, respectively. The percentage of nitrogen in the same grain was 2.77, 2.85, 2.11, and 2.06, respectively. Expressing the amount of nitrogen in grams per 1,000 kernels we would get 1.04, .99, .58, and .76, respectively. From this it will be observed, contrary to the rule, that the smaller grains produced on the Maryland soil contained much less nitrogen than the larger grains. One thousand grains of the seed growTi on the same plats the following season weighed 28.6, 29.6, 22.6, and 36.1 grams, respectively. The percentage of nitrogen was 2.48, 2.33, 3.02, and 1.91, respectively; or again representing this as grams of nitrogen per 1,000 kernels it would be .71, .69, .68, .69, respectively. It is clearly seen in this case that the different seeds, although varying considerably in size, contain practically the same quantity of nitrogen. The weight of the different constituents in 1,000 kernels is summarized in the follow- ing table : 572 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION. TABLE XII. Weight in grams per 1,000 kernels. Season 1908-1909. Plot. A 2, « » 2 CD c* f O 1 o 1 o 1 o o :3b TO | * « o J* 7§ O O O S O ' <=2 j §* o 12 3 •is o <-► » CO 7 ET Grams sulphuric acid per 1,000 kernels o |i I 1 h Check 37.38 34.77 27.42 37.1 1.04 .99 .58 .76 .32 .28 .33 .29 .21 .18 .18 .20 .31 .26 .17 .20 .025 California .039 Maryland .041 Kansas _ .058 Season 1909-1910. Check 29.71 28.73 22.69 36.11 .71 .70 .69 .69 .25 .23 .23 .21 .17 .17 .16 .20 .26 .20 .22 .22 .026 California _ _ .050 Maryland .025 Kansas .071 Conclusions. — It must be said that the results so far obtained do not shed as much light upon the primary question as to the influence of the soil nitrogen upon the nitrogen content of the wheat as could be desired, possibly on account of the short duration of the experiment. It is evident, however, that in neither of the series of trials has the grain carrying the larger nitrogen content been obtained from the soil plat having the heaviest total nitrogen content. In the light of the present data it seems quite certain that the soil nitrogen content has very little, if any, direct influence upon the nitrogen content of grain grown upon such soil, and that some climatic factor is sufficient to entirely over- shadow the soil factor. This is entirely in harmony with the work of Dr. Le Clerc previously reviewed, and also with the well known wide fluctuation of the nitrogen content of wheat from season to season, although the grain be grown upon the same soil. It may be that certain physical factors, enabling the soil to hold moisture better at certain periods of the plant's growth are responsible for the difference, but of this we have no data so far as these plats are concerned. The results also show that a chemical analysis of a soil by the ten-hour hydrochloric acid (sp. gr. 1.115) digestion method reveals no definite relation between the chemical composition of the soil and the crop. Further, it appears that the nitrogen content of an original seed when grown elsewhere than in a climate within which it has been acclimated, has little or no influence upon its progeny, and that even though it be acclimated still some seasonal climatic factor is sufficient to either lower the nitrogen content of a high-gluten wheat or raise the nitrogen content of a low-gluten original. ADDENDA. Since the preparation of the previous matter, analyses have been made of the product of the 1911 crop from the triangular soil exchange plats. For the season of 1911, the original for each of the plats and the general check consisted of the seed produced on the same plat the preceding season. The results are stated below : TABLE XIII. Showing analyses of wheats from triangular soil exchange plats 1911. Interior plants. Check. Orig- inal. 1911 crop. California. Orig- inal. 1911 crop. Kansas. Orig- inal. 1911 crop. Maryland. Orig- inal 1911 crop. Total protein Ash Alcohol— Soluble nitrogen Salt— Soluble nitrogen Percentage typical kernels Percentage starchy kernels. __ Kernels in 10 grains 13.45 2.15 .91 .51 90.40 .6 374 12.04 1.60 .93 .50 88.80 11.2 261 14.27 2.11 1.01 .54 100.00 374 10.56 1.88 .76 .45 50.8 49.2 289 11.23 1.85 .76 .46 64.7 35.3 204 9.61 1.76 .70 .47 46.0 54.0 265 17.44 2.19 1.19 .57 100.00 474 13.20 1.78 .80 .50 100.00 425 TABLE XIV. Showing analyses of wheats from triangular soil exchange plats 1911. Exterior plants. Check. Orig- inal. 1911 crop. California. Kansas. Orig- inal. 1911 Orig- crop. inal. 1911 crop. Maryland. Orig- 1911 inal. crop. Total protein Ash Alcohol— Soluble nitrogen ___ Salt— Soluble nitrogen Percentage typical kernels... Percentage starchy kernels.. Kernels in 10 grams 13.45 2.15 .91 .51 90.4 .6 347 12.04 1.60 .93 .50 88.8 11.2 261 14.27 2.11 1.01 .54 100.00 374 11.60 1.89 .82 .51 61.3 38.7 289 11.23 1.85 .76 .46 64.7 35.3 204 12.12 1.80 .90 .56 82.4 17.6 269 17.44 2.19 1.19 .57 100.00 474 12.52 1.72 .72 .57 96.8 3.2 As in the previous two seasons, the grain produced on the Maryland soil was pinched and the kernels were small, which fact again renders this product not comparable with the others. Showing relative yield from the triangular soil exchange plats 1911. The ash content of the produce of the check plat is markedly low when compared with the others, which are very uniform in ash content. The selected interior product of each of the California and Kansas plats shows a marked uniformity in the nitrogen and ash content as well as in the number of kernels in 10 grams, and the percentage of starchy and typical kernels. They show, however, less nitrogen than the grain from the check plat. On comparing the chemical characteristics of the exterior plants it will be noticed that the figures in all of the columns for the grain from the check and Kansas plats agree tolerably well. The most striking point brought out by these last figures, is the dif- ference in composition and appearance of the grain produced on the same soil, viz. : the check plat and the other California soil plat. There is a greater difference between these two products than exists between the others or between these and the others. This difference, particularly with respect to the nitrogen, is not nearly so great, however, as that brought out by Le Clerc (loc. cit.) from his experiments in which both soil and climate were variable factors. It does, however, indicate that some other factors pertinent to the physical or biological conditions of the soil play an important role since we have, in our own experiment, only one variable factor, viz. : the soil. Moreover, the slight variations occurring in the chemical characteristics in these experiments, being considerably less than those observed by Le Clerc, adds strongly to the belief that the climatic factor is the chief one in producing changes in the chemical composition of wheat. STATION PUBLICATIONS AVAILABLE FOR DISTRIBUTION. REPORTS. 1896. Report of the Viticultural Work during the seasons 1887-93, with data regard- ing the Vintages of 1894-95. 1897. Resistant Vines, their Selection, Adaptation, and Grafting. Appendix to Viti- cultural Report for 1896. 1902. Report of the Agricultural Experiment Station for 1898-1901. 1903. Report of the Agricultural Experiment Station for 1901-03. 1904. Twenty-second Report of the Agricultural Experiment Station for 1903-04. BULLETINS. Reprint. Endurance of Drought in Soils of the Arid Region. No. 128. Nature, Value, and Utilization of Alkali Lands, and Tolerance of Alkali. (Revised and Reprint, 1905.) 133. Tolerance of Alkali by Various cultures. 14 7. Culture Work of the Sub-stations. 149. California Sugar Industry. 151. Arsenical Insecticides. 153. Spraying with Distillates. 159. Contribution to the Study of Fer- mentation. 1G2. Commercial Fertilizers. (Dec. 1, 1904.) 165. Asparagus and Asparagus Rust in California. 167. Manufacture of Dry \vines in Hot Countries. 168. Observations on Some Vine Dis- eases in Sonoma County. 169. Tolerance of the Sugar Beet for Alkali. 170. Studies in Grasshopper Control. 171. Commercial Fertilizers. (June 30, 1905.) 172. Further Experience in Asparagus Rust Control. 174. A New Wine-cooling Machine. 176. Sugar Beets in the San Joaquin Valley. 17 7. A New Method of Making Dry Red Wine. 178. Mosquito Control. 179. Commercial Fertilizers. (June, 1906.) 180. Resistant Vineyards. 181. The Selection of Seed- Wheat. 15 2. Analysis of Paris Green and Lead Arsenic. Proposed In- secticide Law. 183. The California Tussock-moth. 184. Report of the Plant Pathologist to July 1, 1906. 185. Peport of Progress in Cereal Investigations. 186. The Oidium of the Vine. No. 187. 188. 189. 190. 191. 192. 193. 194. 195. 197. 198. 199. 200. 201. 202. 203. 204. 205. 206. 207. 208. 209. 210. 211. 212. 213. 214. 215. Commercial Fertilizers. (January, 1907.) Lining of Ditches and Reservoirs to Prevent Seepage and Losses. Commercial Fertilizers. (June, 1907.) The Brown Rot of the Lemon. California Peach Blight. Insects Injurious to the Vine in California. The Best Wine Grapes for Cali- fornia ; Pruning Young Vines ; Pruning the Sultanina. Commercial Fertilizers. (Dec, 1907.) The California Grape Root- Worm. Grape Culture in California ; Improved Methods of Wine- making ; Yeast from California Grapes. The Grape Leaf-Hopper. Bovine Tuberculosis. Gum Diseases of Citrus Trees in California. Commercial Fertilizers. (June, 1908.) Commercial Fertilizers. (Decem- ber, 1908.) Report of the Plant Pathologist to July 1, 1909. The Dairy Cow's Record and the Stable. Commercial Fertilizers. (Decem- ber, 1909.) Commercial Fertilizers. (June, 1910.) The Control of the Argentine Ant. The Late Blight of Celery. The Cream Supply. Imperial Valley Settlers' Crop Manual. How to Increase the Yield of Wheat in California. California .White Wheats. The Principles of Wine-making. Citrus Fruit Insects. The House Fly in Its Relation to Public Health. CIRCULARS. No. 1. Texas Fever. 5. Contagious Abortion in Cows. 7. Remedies for Insects. 9. Asparagus Rust. 11. Fumigation Practice. 12. Silk Culture. 15. Recent Problems in Agriculture. What a University Farm is For. 19. Disinfection of Stables. 29. Preliminary Announcement Con- cerning Instruction in Practical Agriculture upon the University Farm, Davis, Cal. 30. White Fly in California. 32. White Fly Eradication. 33. Packing Prunes in Cans. Cane Sugar vs. Beet Sugar. 36. Analyses of Fertilizers for Con- sumers. 39. Instruction in Practical Agricul- ture at the University Farm. 46. Suggestions for Garden Work in California Schools. 47. Agriculture in the High Schools. No. 48. Butter Scoring Contest, 1909. 50. Fumigating Scheduling. 51. University Farm School. 53. Announcement of Farmers' Short Courses for 1910. 54. Some Creamery Problems and Tests. 55. Farmers' Institutes and University Extension in Agriculture. 58. Experiments with Plants and Soils in Laboratory, Garden, and Field. 59. Tree Growing in the Public Schools. 60. Butter Scoring Contest, 1910. 61. University Farm School. 62. The School Garden in the Course of Study. 63. How to Make an Observation Hive. 64. Announcement of Farmers' Short Courses for 1911. 65. California Insecticide Law. 66. Insecticides and Insect Control.