The investigation was undertaken to study the possible effects of fertilizers and cropping systems on the quality of grain protein as measured by total content and proportions of nine essential amino acids. Amino acid determinations were made on acid hydrolysates of ground grain using a microbiological assay method. All grains were grown on sulfur‐deficient gray wooded soil. Most of the samples were from plots originally laid out in 1930 for long term tests to compare the effects on crop yields of various fertilizers applied in a wheat‐fallow cropping system and in a rotation in which mixed legume hay was grown in two years out of five. The protein content of wheat grown in the rotation was higher than that of wheat from the wheat‐fallow plots and the barley grown the first year after legumes contained more protein than that grown the third year after legumes. Increases in percentage of protein (N × 6.25) in the grains were associated with some decrease in quality as measured by the percentage that nine essential amino acids contributed to the protein. This decrease in quality was less marked in grains from rotation plots to which fertilizers containing sulfur were applied than in those from plots treated with fertilizers that did not supply sulfur.

and the total nitrogen-total sulphur ratio also showed differences, their magnitude was not of the same order as with these two fractions.Similar determinations for red clover showed the diiTerences to be smaller than for alfalfa and alsike clover and they appear ro be of doubtful value for predicting the need for sulphur fertilization.

Samples of barley having low, medium, and high protein contents were obtained from field fertilizer experiments conducted during 1957 and 1958. The nutritive values of these grains were compared in a feeding trial employing rats as the test animal, and by a semi-quantitative chromatographic estimation of 13 amino acids in the grains. For the feeding experiment all diets were supplemented with minerals and vitamins. Each grain sample was fed with and without added lysine. Animal growth and food efficiency improved with increase in protein levels and with addition of lysine. The 13 amino acids determined accounted for approximately two-thirds and four-fifths of the total protein in the 1957 and 1958 grains respectively. Possible causes of these differences are discussed. The analytical data revealed that percentages of 9 essential amino acids in barley protein were approximately double the amounts reported by other analytical procedures. Compared to previously reported data, there were some noteworthy variations for individual amino acids. There may be practical applications of the procedure used for amino acid determinations in evaluating the protein quality of feed grains. The availability of such a technique could be very helpful to plant breeders concerned with the production of feed grain varieties. The feeding experiment established the nutritive importance for rats, and presumably for swine, of grain protein increases resulting from nitrogen fertilization.

Rate of gain, efficiency of food utilization, and nitrogen retention by weanling rats were used as criteria to determine the nutritive value of wheat grown on a sulphur-deficient Grey Wooded soil. All diets were supplemented with minerals, vitamins, and lysine. Grain from an area continuously cropped to wheat-fallow and from an area cropped to a 5-year grain-legume rotation were compared. On Breton loam, a Grey Wooded soil, grain is highly responsive to fertilization with nitrogen; and legumes are very highly responsive to sulphur fertilization. Samples were fed from plots receiving the same fertilizer treatments in each cropping system. Fertilizer treatments and cropping systems both caused occasional significant differences, and were associated with some consistent trends for differences, in nutritive value of wheat. In general, the grain was of substantially superior nutritive value when grown following legumes; in one year these differences tended to be greater with fertilizer treatments which increased yields. During the same year fertilization with manure tended to improve the nutritive value of fallow wheat. The animal growth and food efficiency were closely related to the protein content of the foods. There were differences between results obtained in 2 successive years. While the differences may have been due to the effect of seasons or to the biennial application of fertilizers they appeared to be closely related to protein content of the grain, a characteristic which long-time data have shown to be highly variable in grain from the Breton plots.

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