Nitrogen mineralization in soils amended with composted and uncomposted poultry litter

Abstract

When applied to land, poultry litter can be a valuable source of plant macro‐ and micro‐nutrients. However, if poultry litter is overapplied, then its mineralized nitrogen (N) can contaminate ground and surface waters. Composting poultry litter may slow down the rate of N mineralization thereby reducing the risk of environmental pollution. The objective of this work was to determine if N mineralization from composted poultry litter is slower than that from uncomposted poultry litter when these materials are mixed with soil. Two composted broiler litters, one composted hen manure, and two uncomposted broiler litters were mixed with Dothan loamy sand (pH 4.3) and Hiwassee fine sandy loam (pH 5.5), and incubated at 25°C for 56 d. Subsamples for inorganic N determinations were taken at 1, 2, 4, 7, 14, 21, 28, and 56 d. After 56 d, the proportion of organic N mineralized ranged from 0.4 to 5.8% for the composted materials, and from 25.4 to 39.8% for uncomposted broiler litters. These results indicate that composted poultry litter releases N more slowly than uncomposted poultry litter, and therefore poses less environmental risk than uncomposted poultry litter.