Search National Agricultural Library (NAL) Digital Collections
Showing item 0 of
from your search.
Bioactive phosphorus loss in simulated runoff from a phosphorus-enriched soil under two forage management systems
- Although runoff from phosphorus (P)-enriched soils contains more P than the functionally defined molybdate-reactive P, information on the biological significance of the remaining fraction is limited. A study was conducted to characterize distributions of inorganic and enzyme-labile P forms in simulated runoff from a silt loam soil (Typic Hapludults) under orchard grass (Dactylis glomerata L.)-red clover (Trifolium pratense L.) and no-till forage-type soybean (Glycine max [L.] Merr.)-wheat (Triticum aestivum L.) systems after the fall harvest. Forage management effects on runoff composition and on relationships between soil water-extractable P (WEP) in runoff and bioactive P pools were determined after eight annual manure applications. Concentration and mass distributions of P forms in runoff over time were lognormally distributed, and four parameters defined the distributions' amplitude and asymmetry. The more inclusive total bioactive P (EDTA-PHP) fraction was found in greater concentration and mass than WEP. Peak concentrations and mass loads were greater from soil amended with manure P than untreated soil and from soil under orchard grass-clover than soil under soybean-wheat rotation. The strength of correlations between predicted WEP mass loads and soil P pools was in the order EDTA-PHP > ligand-exchangeable inorganic P > Mehlich-3P, suggesting that runoff P forms were directly associated with soil available P fractions that were partly derived from enzyme-mediated processes. The results also suggested that knowledge of the P release pattern was as important a factor as mass load because management intensity and yield potentials of these forage systems can alter the characteristics of the loss process.
Green, V.S. , Dao, T.H. , Stone, G. , Cavigelli, M.A. , Baumhardt, R.L. , Devine, T.E.
agricultural runoff , losses from soil , phosphorus , agricultural soils , silt loam soils , pastures , Dactylis glomerata , Trifolium pratense , no-tillage , Glycine max , soybeans , Triticum aestivum , winter wheat , crop rotation , forage crops , soil amendments , cattle manure , Maryland
- Includes references
- Soil science 2007 Sept., v. 172, no. 9
Journal Articles, USDA Authors, Peer-Reviewed
- Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.