Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 10/25/2001
Publication Date: 10/25/2001
Citation: KOVAR, J.L., GASTON, L., DRAPCHO, C., TAPADAR, S. RELATION OF SOIL P TO SURFACE RUNOFF P FOR FOUR SOILS AMENDED WITH POULTRY LITTER. ASA-CSSA-SSSA ANNUAL MEETING ABSTRACTS. 2001. CD-ROM. MADISON, WI. Interpretive Summary:
Technical Abstract: Long-term application of poultry litter has led to a build-up of phosphorus (P) in the surface layer (0-15 cm) of certain Coastal Plain Ultisols of north Louisiana. Sound P management requires a better understanding of the relationship between surface soil P and runoff P for the soils and environmental conditions in the region. In this field study, we tracked two-year changes in total P, total inorganic P, available P (Bray 1 P, Bray 2 P, Mehlich 3 P), and resin-exchangeable P on four established pasture sites with histories of poultry litter application ranging from one year to more than 20 years. Three replicated plots at each site were subjected to a series of four simulated rainfalls, and concentrations of dissolved and total P in runoff related to the measures of soil P. Runoff P was also related to dissolved P released from surface soil in a miscible displacement experiment. Among the various measures of soil P, only resin- exchangeable P consistently decreased during the two-year course of this study. Although all measures of extractable soil P were significantly correlated with P in runoff, resin-exchangeable P was the best indicator of runoff P, accounting for 53% of the variability in the data. Use of P desorption during miscible displacement through short columns as a model for P mobilization into runoff better predicted P losses. This approach accounted for up to 70% of the variability in P runoff concentrations. The superior predictive ability of the exchange resin extraction and miscible displacement methods warrants further study and refinement.