Litter quality and nitrogen release in tropical agriculture: a synthesis

Abstract

 Litter of high quality is required for increased soil organic matter turnover and improved crop production in tropical agroecosystems. Studies on litter quality using plant residues have produced inconsistent results. This study reports on previously published data on litter quality, in an attempt to define universal chemical determinants controlling N release in tropical agriculture. N concentrations and polyphenol/N ratios are determinants of the N release of plant residues with limited N concentrations, i.e. of <2% and <1%, respectively. Lignin levels and lignin/N ratios were not observed to be good predictors of N release. The C/N ratio was found to be the best determinant of N release for a wide range of residue N concentrations. More specifically, critical levels of C and plant nutrients which limit the enzyme activities of microbial decomposers were found to be important for determining nutrient release.