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Agricultural sources of nonpoint pollution are a major source of nutrients to the Gulf of Mexico. The problems of the Gulf of Mexico are due to the agricultural practices along the Mississippi River and in the Mississippi River Basin. The Mississippi River drains 40% of the contiguous United States (Turner, R.E., 1994). The highly fertile land in the Mississippi River Basin produces 84% of the nation's corn, and 81% of the soybeans (Burt, J.P., and K. Alt, 1995). Therefore, much of the United States farmland has the potential to contribute nutrients that end up in the Gulf of Mexico. Much of the fertilizers applied to this cropland eventually make, its way into the Gulf of Mexico by runoff.
In order for agricultural nutrients to be transported soil erosion and nutrients on the surface of the soil must be in the environment (Burt, J.P., and K. Alt, 1995). These nutrients are then eroded from the field to the stream. The amount of nutrients and soil transported depends on the type of land the material is transported through. If wetlands interrupt the runoff flow then some of the eroded soil and nutrients will be removed. Then these eroded materials are integrated into the stream, where they can have some type of impact on the aquatic environment. In this case the impact of agricultural runoff is hypoxia in the Gulf of Mexico.
Hypoxia is the depletion of oxygen in a body of water. This depletion is largely due to agriculture contributing nitrate to surface water. According to Power et. al. (1998) "the global nitrate problem is most apparent in the North Central Region of the United States where 83% of the nation's corn is produced and 53% of the commercial nitrogen fertilizer is used." This nitrate-nitrogen is supplied to the waterways via mineralization of soil organic matter and through the application of fertilizers and animal manure to farmland. In addition, the dairy, pork, swine, and poultry industry also produce large amounts of nitrogen and phosphorus in untreated wastewater, which can be discharged into local streams.
The hypoxic condition that has occurred in the Gulf of Mexico is largely due to the farming practices in the Mississippi River Basin. However, this problem has the potential to be reduced if the agricultural industry is willing to implement some best management practices for controlling erosion, fertilizers, manure, and grazing. If implemented properly these practices could drastically improve the hypoxic condition in the Gulf of Mexico. These potential solutions for reducing nutrient loading need to be backed by proper incentives and government funding, which will hopefully cause the farmers to implement some of these conservation practices.
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