Evaluation of organic matter and nutrient composition of partially decomposed and composted spent pig litter

Abstract

Characterization of soil‐applied organic material is necessary in order to clarify the nature of the organic matter and nutrients in it In this study, the organic matter and nutrient contents of the spent pig litter (a mixture of partially decomposed pig manure and sawdust) was characterized before and after windrow composting to: (1) determine their changes during composting, and (2) assess the suitability of the composted spent litter as a soil amendment Results demonstrated mat the time required to teach maturity, and the composition of composted spent litter, depended on the chemical properties of the initial compost feedstock as well as the compost strategies used during composting. Total N, P, and K concentrations of the composted litter depended on chemical properties of the initial material. On the other hand, ON ratio, humic and fulvic add and cation‐exchange capacity were influenced by differences in composition of the initial spent litter and composting strategy. If moisture content was maintained weekly at 60% with a four‐day turning frequency, the litter reached maturity in 56 days. Maturation of spent litter was accompanied by a decline in total C, water‐extractable metals, NH4+‐N, increase in ash, (NO3‐+NO2‐)‐N, humic acid, humic acid fulvic add ratio, and cation exchange capacity, and elimination of phytotoxidty. The stability of nutrient and organic matter, acceptable pH and electrical conductivity values, and low levels of undesirable components such as heavy metals and phytotoxic compounds of the spent litter provided substantial evidence that agronomically suitable compost can be obtained after composting in windrows. © 2003 Taylor & Francis Group, LLC.