|Mccaslin, Stephanie - TETRA TECH|
Submitted to: Nonpoint Pollution Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 30, 2001
Publication Date: N/A
Technical Abstract: Nutrient loss from agricultural lands has prompted much discussion about the impact of farming practices on water quality. Observations have been collected from field-scale research and little information exists to compare among watersheds. A study was designed using watershed scale data to define a relationship of nitrogen present in surface waters relative to agricultural practices in Upper Midwest watersheds. These watersheds represented a range of cropping intensities in Illinois, Iowa, and Missouri. Nitrogen concentration present in the rivers was based on the drainage area for the watershed along with the amount of harvested land. Loss of N occurred from every watershed but a large variation exists among watersheds. Higher application rates of N in Iowa and Illinois create greater N loadings from these watersheds. A consistent trend in the amount of N lost relative to N applied was not found in these watersheds. This study illustrates the amount of N does need to be reduced, but it shows no significant relationship from the amount applied to the amount lost or the amount of cropped land within a watershed. Nutrient management guidelines will require a watershed scale approach with the incorporation of management practices with watershed characteristics.