NITROGEN MINERALIZATION AND AMMONIA VOLATILIZATION FROM FRACTIONATED POULTRY LITTER

Passing poultry litter through a 0.83-mm sieve generates a fine fracti on higher in N concentration and cheaper to transport per unit of N th an the whole litter. One objective of this work was to determine if th e organic N in the fine fraction undergoes faster mineralization than that in the whole litter. Whole litter or fine fraction from three pou ltry houses was either mixed with samples of Dothan loamy sand (fine-l oamy, siliceous, thermic Plinthic Kandiudult) or applied on the soil s urface at a rate of 100 kg N ha-1. The treatments were incubated at wa ter field capacity and 25-degrees-C, with samples extracted at 3, 7, a nd 14 d. Differences in N mineralization were relatively small between materials; by Day 14, the organic N had undergone a slightly higher m ineralization in the fine fraction (51.5%) than in the whole litter (4 4.5%). A second objective was to compare the potentials for net N mine ralization, NH3 volatilization, and respiration of whole poultry litte r and fine fraction stored for 7 d at 25-degrees-C and at two water co ntents (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 la rger in the fine fraction than in the whole litter, whereas respiratio n was similar in both materials. All processes increased with an incre ase in water content. These results suggest that the fine fraction sho uld 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, p articularly at relatively high water contents.