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Estimation of nitrate contamination of an agro-ecosystem outwash aquifer using a nitrogen mass-balance budget

Journal of Environmental Quality

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Abstract

A mass-balance budget of N cycling was developed for an intensive agricultural area in west-central Minnesota to better understand NO3/- contamination of ground water in the Otter Tail outwash aquifer. Fertilizer, biological fixation, atmospheric deposition, and animal feed were the N sources, and crop harvests, animal product exports, volatilization from fertilizer and manure, and denitrification were the N sinks in the model. Excess N, calculated as the difference between the sources and sinks, was assumed to leach to ground water as NO3/-. The budget was developed using ground water data collected throughout the 212-km2 study area. Denitrification was estimated by adjusting its value so the predicted and measured concentrations of NO3/- in ground water agreed. Although biological fixation was the largest single N source, most was removed when crops were harvested, indicating that inorganic fertilizer was the primary source of N reaching the water table. It was estimated that denitrification removed almost half of the excess NO3/- that leached below the root zone. Even after accounting for denitrification losses, however, it was concluded that the ground water system was receiving approximately three times as much N as would be expected under background conditions.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Estimation of nitrate contamination of an agro-ecosystem outwash aquifer using a nitrogen mass-balance budget
Series title:
Journal of Environmental Quality
Volume
28
Issue:
6
Year Published:
1999
Language:
English
Publisher:
American Soc of Agronomy Inc
Publisher location:
Madison, WI, United States
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
2015
Last page:
2025
Number of Pages:
11