Longitudinal Loading and Nutrient Compositional Gradients in an Agriculturally Managed Watershed in West-Central Wisconsin
Abstract
The purpose of this research was to describe and quantify biologically labile and refractory nitrogen and phosphorus species, transformations, and loads along the longitudinal axis of a river draining an intensively managed agricultural watershed. Excessive nutrient runoff (primarily as phosphorus) in agriculturally managed watersheds is a primary cause for eutrophication of Corps of Engineers and other receiving waters. Because agricultural soils are often managed for crop uptake of nitrogen (N), rather than phosphorus (P), additions of fertilizers and manures have resulted in the buildup of soil P in excess of crop needs that can be transported to receiving waters during runoff (Lemunyon and Gilbert 1993, Sharpley et al. 1994, Sharpley 1995). In addition, watersheds managed for livestock (such as dairy operations) rely on frequent soil applications as a means of manure management that also results in the buildup of excessive nutrient levels in the soil. Simulation of N and P runoff via modeling is critical for the development of management scenarios to control excessive nutrient loading in agriculturally managed watersheds. However, algorithms need to be improved to more accurately predict transformations, transport, and fate of biologically labile nutrient forms that are either directly available for biological uptake or that can be recycled in receiving waters. Input data are also needed to verify these model improvements and predictions. The objectives of this study were to examine biologically labile and refractory N and P loadings, composition, and transformations in the agriculturally managed Upper Eau Galle River Watershed, located in west-central Wisconsin.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2004
- Accession Number
- ADA434935
Entities
People
- Carlos E. Ruiz
- Harry L. Eakin
- John W. Barko
- William F. James
Organizations
- Engineer Research and Development Center