Effects of Long-Term Fertilizer and Manure Treatments on the Distribution and 15N Natural Abundance of Amino Acids in the Palace Leas Meadow Hay Plots: A Preliminary Study

The concentration and 15N natural abundance of individual amino acids in soils treated annually, since 1897. with either farmyard manure (FYM), (NH4)2SO4+PK, (NH4)2SO4-only, or untreated, are presented. Total amino acid-N contents were substantially higher in the FYM treated soil and the O horizon of the (NH4)2SO4-only treatment compared with the A horizon of the same treatment, and both the (NH4)2SO4+PK treated and untreated soils. The percentage N content as glycine, isoleucine, glutamic acid, tyrosine and cysteic acid, were generally higher in the amended soils, whereas those of lysine, leucine and serine were lower, than in the untreated soil. The δ15N values of phenylalanine, ornithine, serine, glycine and isoleucine were influenced by any N treatment, and those of leucine by soil pH.