NITROGEN MINERALIZATION IN SOILS AMENDED WITH COMPOSTED AND UNCOMPOSTED POULTRY LITTER

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 mineral ization thereby reducing the risk of environmental pollution. The obje ctive of this work was to determine if N mineralization from composted poultry litter is slower than that from uncomposted poultry litter wh en these materials are mixed with soil. Two composted broiler litters, one composted hen manure, and two uncomposted broiler litters were mi xed with Dothan loamy sand (pH 4.3) and Hiwassee fine sandy loam (pH 5 .5), and incubated at 25-degrees-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 b roiler litters. These results indicate that composted poultry litter r eleases N more slowly than uncomposted poultry litter, and therefore p oses less environmental risk than uncomposted poultry litter.