Mineralization and nitrification of nitrogen from poultry litter applied to soil

ABSTRACT

The fertilizer or pollutant effect of the nitrogen present in animal wastes depends on the mineralization of the organic N forms as well as nitrification, in addition to other factors. The objective of this study was to quantify both mineralization and nitrification rates of N applied to the soil from poultry litter. The experiment was carried out in a greenhouse using samples of a Humic Haplumbrept containing 55 g kg^-1 of organic matter, 400 g kg^-1 of clay and pH 6.0. Treatments consisted of combination of rates of poultry litter (equivalent to 0, 4, 8 and 16 Mg ha^-1) and a single rate of urea, all incorporated in soil or applied on surface. Mineral N (N-NH4+ and N-NO3-) in the soil was determined at 2, 6, 12, 19, 26, 32 and 48 days after treatment application. The concentrations of ammonium decreased and that of nitrate increased over time due to nitrification, which was faster when poultry litter was incorporated to the soil in comparison to surface applied. Mineral soil N recovery from the amount of total N applied as poultry litter was small regardless of the application form: after 48 days, mineral N was 22 and 15.7% for application rates of 4 and 16 Mg ha-1, respectively.

Key words:
animal waste; organic nitrogen; methods of fertilizer application