Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 6, 1999
Publication Date: N/A
Technical Abstract: Protection zones around wellheads have been used to limit aquifer contamination by surface-applied chemicals and nutrients. One method of protecting these aquifers is to limit uses on their overlying landscapes that pose the greatest risk of contamination. This constraint is especially important in rural settings where production agriculture is common. The objective of this study was to identify those crops and management systems that pose the greatest risk of nitrate contamination of drinking water supplies in wellhead protection zones. Simulations were performed using the computer model GLEAMS (Groundwater Loading Effects of Agricultural Management Systems) and data files for various climates, soils, and common field crops. Results indicate that perennial cropping systems require fewer external fertilizer inputs to attain potential yield levels and limit the amount of nitrates available for leaching. The greatest amount of nitrates leached below the root zone occurred under annual crops (corn, soybean) using current Best Management Practices (BMPs). Increasing acreages of perennial crops (alfalfa, bromegrass, orchardgrass) in wellhead protection zones resulted in lower risks of nitrate leaching to underlying aquifers than growing annual crops, regardless of soil type or climate. A reduction of fertilizer inputs (75% or less of BMP recommendations) to annual crops in these areas was also effective in limiting nitrate contamination, but with a subsequent reduction in yield. Drinking water quality can be better protected if initiatives were undertaken to establish crop management systems in wellhead protection zones that promote perennial crops and/or limit fertilizer inputs on annual crops.