Nine Essential Amino Acids in the Protein of Wheat and Barley Grown on Sulfur‐Deficient Soil

Abstract

AbstractThe 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.