Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2002
Publication Date: 6/1/2002
Citation: Preusch, P.L., Adler, P.R., Sikora, L.J., Tworkoski, T. 2002. Nitrogen mineralization rates and phosphorus availability in composted and uncomposted poultry litter. Journal of Environmental Quality. 31:2051-2057. Interpretive Summary: Accelerated eutrophication of waterways often results from repeated high rate agricultural applications of poultry and other manure. Excess nutrients, particularly nitrogen (N) and phosphorus (P), from surface water run-off causes algal blooms that can produce toxins which are harmful to humans and to the ecosystem. Previous work has indicated that composting poultry litter may provide a beneficial alternative method for handling litter due to immobilization of nutrients, particularly N. However loss of P from composted manures is less well understood. The objectives of this study were to determine and compare the mineralization rate of N and availability of P from composted poultry litter (CPL) and fresh poultry litter (FPL) incubated with two different soils (sandy loam and silt loam) that are representative of soils where the poultry litter was produced and where it would be land-applied. Nitrogen mineralization rates were lower for CPL than for FPL. However, composting did not consistently reduce P and P was as available in CPL as in FPL. The upshot of the research is that application of CPL based on N requirements of crops may result in significant P inputs that can negatively impact the environment.
Technical Abstract: Poultry litter applications to land have been based on N concentration in litter, resulting in application of P in excess of plant requirements which may cause degradation of water quality in the Chesapeake Bay Watershed. The effect of litter source (the Delmarva Peninsula and Moorefield, West Virginia) and composting of poultry litter, on N mineralization and availability of P in two soil types (sandy loam and silt loam) was determined in a controlled environment for 120 d. N mineralization (percent total organic N converted to inorganic nitrogen) rates were higher for fresh litter (range of 42 to 64%) than composted litter (range of 1 to 9%). The N mineralization rate of composted litter from either source was not different for each soil type (7 to 9% in sandy loam and 1 to 5% in silt loam) even though composting conditions were completely different at the two composting facilities. Litter source had a large impact on N mineralization rates of fresh but not composted poultry litter. Compostin yielded a more predictable and reliable source of mineralizable N than fresh litter. Water-extractable phosphorus (WEP) was similar in soils amended with composted litter from WV and fresh litter from both sources (approximately 10 to 25 and 2 to 14 ug P g-1 sandy loam and silt loam, respectively). Mehlich 1-extractable phosphorus (MEP) was similar in soils amended with WV fresh litter and composted litter from both sources (approximately 100 to 140 and 60 to 90 ug P g-1 sandy loam and silt loam, respectively). These results suggest that the composting process did not consistently reduce WEP and MEP, and P can be as available in composted poultry litter as in fresh poultry litter.