Crop selection, tillage practices, and chemical and nutrient applications in two regions of the Chesapeake Bay Watershed
The objectives of this study were to obtain information on crop selection, tillage, and nutrient and chemical use on cropland having varying sediment loading and leaching potential. Additional objectives were the determination of economic, attitudinal, and demographic factors related to these agricultural practices. The study was carried out in Virginia in three counties of the Northern Neck region (Lancaster, Northumberland, and Westmoreland) and in Rockingham County. In each area, a stratified random sample of 120 sites with varying leaching and sediment loading potential was drawn from the Virginia Geographic Information System (VirGIS) database of cropland. Information on cultural practices on the sites as well as other farm and farmer characteristics was obtained through personal interviews with farm operators.
Survey responses indicate that farmers are concerned about the effects of pollution on water quality-particularly drinking water. However, farmers tend not to see actions on their own farms as contributing to water quality damage. Most farmers do not agree that runoff and leaching of nutrients and chemicals from their farms contribute to water quality problems. When asked about the sampled sites on their farms, farmers generally responded that the potential for water quality damage caused by leaching and erosion was low. Their assessment of potential damage did not increase significantly on sites with high leaching or sediment loading potential.
In the Northern Neck, farmers generally apply nitrogen and phosphorus at close to recommended rates. In Rockingham County, nitrogen is applied at below recommended rates, while phosphorus is overapplied due to heavy manure applications. Farmers' tillage practices, crop rotations, and nutrient and pesticide application rates generally do not vary according to site leaching and sediment loading potential. Thus, sites with higher leaching and/or sediment loading potential are likely to contribute a disproportionate share of potential loadings to groundwater and surface water.
Further research is needed to determine whether targeting nonpoint pollution control to sites with higher leaching and sediment loading potential is a cost-effective way to achieve water quality protection goals.