Amino Acid Composition of a Manure-Amended Soil: Rhizospheric and Non-Rhizospheric Differences In a Greenhouse Ryegrass Study.

The effects of poultry manure application on soil concentrations of 19 amino acids and two amino sugars were evaluated in a greenhouse pot study of ryegrass (Lolium perenne).  Amino compounds were extracted and analyzed by anion chromatography and pulsed amperometric detection 4, 8, and 16 wk after manure application. No effect on soil amino concentrations was evident with manure application at a rate based on its P content (8.5 Mg poultry manure ha^-1).  When the manure was applied at a 5-fold greater rate, extractable amino compound concentrations in soil were greater than in the unamended control, although not quite by the theoretical amount based on amino content of the amended manure.  The levels of most amino compounds at this high application rate decreased from 4 wk to 16 wk.  Levels of all amino compounds were higher in the rhizospheric soil than in the non-rhizosphere soil at all three sampling times.  This increase was proportionally greater for the acidic and basic amino acids than for all neutral hydrophilic amino acids (threonine, serine, glycine, alanine) but was by far the greatest for the aromatic amino acids tyrosine and phenylalanine.