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Nitrogen and phosphorus availability in composted and uncomposted poultry litter
P L Preusch1, P R Adler, L J Sikora
1Hood College and University of Maryland, 8020 Greenmead Drive, College Park, MD 20740-4000, USA.
Journal of Environmental Quality
|December 10, 2002
Summary
Composting poultry litter significantly reduces nitrogen mineralization rates, making it a more predictable nutrient source. However, phosphorus availability remains similar in both fresh and composted litter.
Area of Science:
- Soil Science
- Environmental Science
- Agronomy
Background:
- Poultry litter application often exceeds crop needs, leading to excess phosphorus (P) and potential water quality degradation in watersheds like the Chesapeake Bay.
- Understanding nutrient dynamics in poultry litter is crucial for sustainable agricultural practices and environmental protection.
Purpose of the Study:
- To evaluate the impact of poultry litter source and composting on nitrogen (N) mineralization and P availability in sandy loam and silt loam soils.
- To determine if composting creates a more reliable N source and affects P solubility compared to fresh litter.
Main Methods:
- A controlled environment study over 120 days assessed N mineralization and P availability (Water-Extractable Phosphorus - WEP; Mehlich 1-Extractable Phosphorus - MEP) in two soil types amended with fresh and composted litter from different sources.
- Nitrogen mineralization was quantified as the percentage of total organic N converted to inorganic nitrogen.
Main Results:
- Nitrogen mineralization rates were substantially higher for fresh litter (42–64%) than composted litter (1–9%).
- Fresh litter from Moorefield, WV, showed higher N mineralization than from the Delmarva Peninsula; composting minimized these source-related differences.
- Composted litter resulted in more predictable N mineralization across soil types, while P availability (WEP and MEP) was not consistently reduced by composting.
Conclusions:
- Composting poultry litter significantly enhances the predictability and reliability of nitrogen release for crop uptake.
- The composting process does not consistently decrease phosphorus availability, suggesting P levels in amended soils can be similar to those with fresh litter.
- Management strategies should consider both N and P dynamics when utilizing composted poultry litter to optimize crop nutrition and minimize environmental risks.