Impact of Organic versus Conventional Farming Practices on Soil Leachate Total Nitrogen Levels

Approximately 50 percent of US drinking water comes from groundwater sources. The US Department of Agriculture (USDA) has standards for organic certification designed to promote groundwater quality. In order to be USDA certified organic, a farmer must 1) never use conventional pesticides, 2) never use fertilizers made with synthetic ingredients, and 3) have been farming organically for over five years. We tested for differences between organic and conventional farming on nitrogen levels in water percolating through soils and hypothesized that organically farmed soil leachate would have lower nitrogen concentrations than conventionally farmed soil leachate. Soil samples collected from fields under organic farming practices did not show significantly lower total nitrate concentrations than samples collected from fields under conventional farming practices. Instead, it was determined that the type of crop being grown has greater influence on leachate total nitrate than the type of farming practice.