ARS | Publication request: Optimization of Buffer-Grass Criteria As Part of National P-Index Evaluation Using Vfsmod-W Model

Submitted to: American Society of Agronomy Abstracts
Publication Type: Abstract
Publication Acceptance Date: July 28, 2004
Publication Date: October 31, 2004
Citation: Sadeghi, A.M., Munoz-Carpena, R., Starr, J.L., Meisinger, J.J., Coale, F.J., Codling, E.E., Graff, C.D. 2004. Optimization of buffer-grass criteria as part of national p-index evaluation using VFSMOD-W model [abstract]. American Society of Agronomy Meetings. 2004 CD-ROM.

Technical Abstract: Continuous application of poultry litter to field crops as a source of fertilizer nitrogen (N) and phosphorous (P) can contribute to excessive soil P levels which increase the potential for higher P losses, both as adsorbed and soluble forms, in runoff and ultimately in surface water resources. As a part of the National P'Index evaluation, a field study to identify factors contributing to P losses from corn plots, using four different poultry manure applications and vegetative buffer combinations, is underway. A process-based vegetative filter strip model (VFSMOD-W) is being used to optimize the effectiveness of vegetative buffers for the selected management options. Preliminary model results indicate better agreement when surface runoff P loads are compared with model predictions, rather than sediment loss concentrations. In our initial model validations, the model predictions consistently overestimated actual sediment losses. A possible explanation for part of this discrepancy is the selection of runoff sampling time and frequencies, especially during the initial phase of runoff events. Analysis also reveals a spatial component to the soil data which could contribute to discrepancies. Details of the complete model application and optimization of buffer lengths for each of the respective field plot/treatment will be presented.