Abstract

Modern American farms often have large numbers of animals and a relatively limited land base to apply the manure. This can lead to the problem of over application of nutrients, particularly nitrogen (N) and phosphorus (P) to agricultural lands. Nitrate (NO₃^-) is soluble in water, hence, it can be easily leached from soils into ground water. As a result, nitrate is the most ubiquitous chemical contaminant in the world's ground-water supplies (Spalding and Exner, 1993). The U.S. EPA established a maximum contaminant level (MCL) of 10 mg NO₃^-N L^-1 for nitrate in drinking water (U.S. EPA, 1995). Nolan et al. (1998) estimated that 24 percent of the ground water in the United States exceeded the U.S. EPA MCL between 1993 and 1995. Likewise, the European Community (EC) has established an upper threshold on drinking water nitrate levels of 11.3 mg NO₃^-N L^-1. Approximately 10 million people in France depend on ground water with nitrate levels above the EC's upper threshold (Spalding and Exner, 1993). Nitrate contamination of ground water near intensive vegetable production has been reported in Japan (Babiker et al., 2004).

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Elise Striz

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