New NAWQA Report on Human and Ecosystem Interactions in an Agricultural Landscape

The following USGS National Water-Quality Assessment (NAWQA) Program report has just been published: Coupe, R. H., Barlow, J. R. B., & Capel, P. D. (2012); “Complexity of Human and Ecosystem Interactions in an Agricultural Landscape.”

The complexity of human interaction in the commercial agricultural landscape and the resulting impacts on the ecosystem services of water quality and quantity are largely ignored by the current agricultural paradigm that maximizes crop production over other ecosystem services. Three examples at different spatial scales (local, regional, and global) are presented where human and ecosystem interactions in a commercial agricultural land- scape adversely affect water quality and quantity in unintended ways in the Delta of northwestern Mississippi.

In the first example, little to no regulation of groundwater use for irrigation has caused declines in groundwater levels resulting in loss of base flow to streams and threatening future water supply. In the second example, federal policy that subsidizes corn for biofuel production has encouraged many producers to switch from cotton to corn, which requires more nutrients and water, counter to national efforts to reduce nutrient loads to the Gulf of Mexico and exacerbating groundwater-level declines. The third example is the wholesale adoption of a system for weed control that relies on a single chemical, initially providing many benefits but ultimately leading to the widespread occurrence of glyphosate and its degradates in Delta streams and necessitating higher application rates of glyphosate as well as the use of other herbicides due to increasing weed resistance. Although these examples are specific to the Mississippi Delta, analogous situations exist throughout the world and point to the need for change in how we grow our food, fuel, and fiber, and manage our soil and water resources.

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