NITROGEN MINERALIZATION AND AMMONIA VOLATILIZATION FROM FRACTIONATED POULTRY LITTER

Passing poultry litter through a 0.83-mm sieve generates a fine fraction higher in N concentration and cheaper to transport per unit of N than the whole litter. One objective of this work was to determine if the organic N in the fine fraction undergoes faster mineralization than that in the whole litter. Whole litter or fine fraction from three poultry houses was either mixed with samples of Dothan loamy sand (fine-loamy, siliceous, thermic Plinthic Kandiudult) or applied on the soil surface at a rate of 100 kg N ha-1. The treatments were incubated at water field capacity and 25-degrees-C, with samples extracted at 3, 7, and 14 d. Differences in N mineralization were relatively small between materials; by Day 14, the organic N had undergone a slightly higher mineralization in the fine fraction (51.5%) than in the whole litter (44.5%). A second objective was to compare the potentials for net N mineralization, NH3 volatilization, and respiration of whole poultry litter and fine fraction stored for 7 d at 25-degrees-C and at two water contents (unamended [0. 12-0.26 kg H2O kg-1] and 0.5 kg H2O kg-1). On an equal-mass basis, net N mineralization and NH3 volatilization were larger in the fine fraction than in the whole litter, whereas respiration was similar in both materials. All processes increased with an increase in water content. These results suggest that the fine fraction should be managed similarly to the whole litter when applied to soil and that it may lose more NH3 than does the whole litter during storage, particularly at relatively high water contents.