Differences in nitrate-N concentrations in,around water in Kansas can be explained by variations in agricultural practices and vadose-zone stratigraphy. In northwestern Kansas, past use of a local stream for tailwater runoff from irrigation and high fertilizer applications for sugar-beet farming resulted in high nitrate-N concentrations (12-60 mg L-1; in both soil and ground water. Nitrogen isotope values from the soil and ground water range from +4 to +8? which is typical for a fertilizer source. In parts of south-central Kansas, the use of crop rotation and the presence of both continuous fine-textured layers and a reducing ground-water chemistry resulted in ground-water nitrate-N values of < 3 mg L-1. The effects of denitrification in the vadose zone and ground water are indicated by enriched ?? 15N values of +10 to +15?. At a site study, irrigated continuous corn was grown on sandy soils with discontinuous fine-textured layers. Here, nitrate-N concentrations were often > 10 mg L-1; in both soil and grounwater. Nitrogen isotope values of +3 to +7? indicate a fertilizer source. Crop rotation decreased nitrate-N values in the shallow ground water (9 m). However, deeper ground water showed increasing nitrate-N concentrations as a result of past farming practices.
Additional publication details
Effects of agricultural practices and vadose zone stratigraphy on nitrate concentration in ground water in Kansas, USA
Pergamon Press Inc
Tarrytown, NY, United States
Larger Work Title:
Water Science and Technology
Proceedings of the 1995 2nd IAWQ International Specialized Conference and Symposia on Diffuse Pollution