Submitted to: Proceedings of the Composting in the Southeast Workshop
Publication Type: Proceedings
Publication Acceptance Date: 8/31/2002
Publication Date: 8/31/2002
Citation: TWORKOSKI, T., ADLER, P.R., SIKORA, L., TAKEDA, F., FERRIER, D., PREUSCH, P. NITROGEN AND PHOSPHORUS AVAILABILITY AND PLANT UPTAKE FROM SOIL TREATED WITH COMPOSTED AND UNCOMPOSTED POULTRY LITTER. Proceedings of the Composting in the Southeast Conf and Exp Workshop. 2002. pp 1-9. Interpretive Summary: Large amounts of poultry manure and bedding (litter) are generated and applied to farm land in the eastern U.S. Litter can be used as a mulch to control weeds and to provide essential plant nutrients but excess nutrients in soil runoff can cause hypoxia and undesirable changes in aquatic communities. In a laboratory experiment, we found that composted litter had lower N release into the soil than fresh (uncomposted) litter. However, water extractable phosphorus (WEP), which represents phosphorus that can cause hypoxia, was not reduced by composting. These results were supported in greenhouse and field experiments where soil WEP and phosphorus uptake by plants were related to the rate of composted litter that was applied. These findings indicate that composting stabilizes nitrogen, but not phosphorus, and that farmers applying compost on a plant-nitrogen-requirement basis may over apply phosphorus and contribute to environmental degradation. The results should assist farmers and consultants develop nutrient management plans that incorporate phosphorus management.
Technical Abstract: Large amounts of poultry manure and bedding (litter) are generated and applied to farm land in the eastern U.S. Manure can provide essential plant nutrients but nutrients in soil runoff can cause hypoxia and undesirable changes in aquatic communities. A laboratory experiment determined N and P availability from fresh poultry litter (FPL) and composted poultry litter (CPL) from two sources mixed with a silt loam. N and P uptake were then determined in strawberry plants grown in soil amended with FPL and CPL in a greenhouse. Finally, a field experiment determined N and P availability to peach trees grown with CPL applied as mulch. In the laboratory, N mineralization rates were significantly higher for FPL than CPL, confirming that composting stabilizes N release from litter. However, water extractable phosphorus (WEP) was similar in soils amended with CPL and FPL, suggesting that WEP availability was not stabilized by the composting process. In the greenhouse experiment FPL and CPL were applied to provide equal total N in soil. Leaf N was greater in plants treated with FPL than with CPL at 6 wk after planting, probably due to higher N mineralization with FPL. After 12 wk, leaf P was greater in strawberry plants grown with CPL than with FPL. Greater leaf P in CPL-treated strawberry plants reinforced the laboratory finding that P was not stabilized by composting. In the field experiment, at 47 weeks after treatment, soil treated with CPL as mulch had significantly greater WEP (30 mg P kg 1 soil) than soil treated with commercial fertilizer (14 mg P kg 1 soil) when both had been applied at the same N-based rate. Together these results indicated that CPL stabilized N but not WEP in CPL-amended soils. Consequently, mismanagement of CPL may be problematic for P release to the environment.