Soil Amino Compound and Carbohydrate Contents Influenced by Organic Amendments

Abstract

Amino compounds (i.e. amino acids and sugars), and carbohydrates are labile organic components and contribute to the improvement of soil fertility and quality. Animal manure and other organic soil amendments are rich in both amino compounds and carbohydrates, hence organic soil amendments might affect soil processes through these labile components. This chapter first reviews the advances in research on soil concentrations of amino compounds and carbohydrates as impacted by animal manure and other organic amendments. The published papers are mainly on the amino compounds and carbohydrate changes in long-term field trials and laboratory or greenhouse incubations, tracking the fate of amendment-derived amino compounds and carbohydrates in soils. To investigate the amino compound and carbohydrate changes in the short-term (16 weeks), we present a greenhouse pot study (4–16 weeks) which demonstrated that poultry manure increased extractable amino compounds when applied to soil at a high rate, and depressed them at a low application rate. The increase at the high rate was further amplified in rhizospheric soils. Whereas microbial activities promoted carbon (C) and nitrogen (N) mineralization, the presence of ryegrass resulted in lower concentrations of amino compounds and carbohydrates. Finally, we recommend that more types of organic amendments be evaluated for their impacts on soil amino compound and carbohydrate levels, and the relationship in changes between the two types of compounds. Such cumulative knowledge would provide a basis for establishing the specific contributions of amino compounds and carbohydrates to soil N and C dynamics over the course of agricultural seasons and beyond.