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Title: NITROGEN IN GROUNDWATER ASSOCIATED WITH AGRICULTURAL SYSTEMS

Author
item Burkart, Michael
item STONER, JEFFREY - USGS-WRD

Submitted to: Geological Society of America Meeting
Publication Type: Proceedings
Publication Acceptance Date: 11/5/2003
Publication Date: 11/5/2003
Citation: BURKART, M.R., STONER, J. NITROGEN IN GROUNDWATER ASSOCIATED WITH AGRICULTURAL SYSTEMS. GEOLOGICAL SOCIETY OF AMERICA MEETING. 2003. CD-ROM. BOULDER, CO.

Interpretive Summary:

Technical Abstract: Research from several regions of the world provides general information to hypothesize hydrologic and agricultural factors contributing of groundwater vulnerability to nitrate contamination. Analysis of groundwater measurements from the U.S. confirm these hypotheses for a variety of agricultural systems. Shallow unconfined aquifers are most susceptible to nitrate contamination associated with agricultural systems. Alluvial and other unconsolidated aquifers are the most vulnerable, and shallow carbonate aquifers provide a substantial but smaller contamination risk. Shallow aquifers located in areas dominated by irrigation are more vulnerable than in non-irrigated areas. Where any of these aquifers are overlain by permeable soils the risk of contamination is larger, particularly in areas with irrigation. The agricultural system of corn, soybeans, and hogs produced significantly larger concentrations of groundwater nitrate than all other agricultural systems with almost 25% of wells yielding nitrate exceeding 10 mg/L. Asia may experience increasing problems because of recent increases in fertilizer use based on generalization of U.S. conditions. Fertilizer-use trends may help strategically locate long-term monitoring that will help answer questions about whether and when proportional changes in concentrations of nitrate will follow these changes in fertilizer. A major contributor to groundwater vulnerability is the distribution of irrigated cropland. This practice is expanding throughout the world, but particularly in Asia. More data and research will be needed in Asia to determine if patterns of water quality degradation in irrigated areas of other regions is repeated here.