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Renewed Focus on Drainage Research in 2002 -- the Year of Clean Water

Tomorrow marks the 30th anniversary of the enactment of the Clean Water Act, a law passed to help the United States protect its most important natural resource. Fittingly, researchers in southern Louisiana are beginning a study this year that may ultimately help reduce the hypoxic, or oxygen deficient, zone in the Gulf of Mexico. Their focus? Improved drainage.

Because field crops, like potted plants, languish when they're over-watered, proper drainage is an important aspect of successful farming. Nearly a third of the farmers in the Midwest rely on subsurface drainage to keep their crops healthy. However, most farmers in Louisiana rely on surface drainage.

A few years ago, Agricultural Research Service scientists Brandon Grigg and Jim Fouss began analyzing data from a subsurface drainage study at the Soil and Water Research Unit in Baton Rouge, La. They hypothesized that underground drains would remove excess water from the soil profile and allow greater infiltration of rainfall through the soil. This could help reduce surface runoff and minimize the amount of agrochemicals carried to ditches and streams.

Surprisingly, the underground drains did not reduce runoff volume or nitrate loss. The reason appears to be the surface soil, which naturally restricts rainfall infiltration and movement of water to the drains.

The scientists have begun a new experiment to study how deep tilling the soil affects rainfall infiltration. In conjunction with this project, they are comparing shallow and deep subsurface drains to see which leaches less nitrate from the soil. Nitrate-nitrogen is a major contributor to the hypoxic zone in the northern Gulf of Mexico, an area incapable of supporting most marine life.

To better understand problems associated with different drainage systems, Dale Bucks, an ARS National Program Leader, recently formed a drainage coalition. It includes researchers from academia, ARS and the USDA Natural Resources Conservation Service, as well as members of the drainage industry and farmer service organizations.

Read more about Grigg's and Fouss's work in the October issue of Agricultural Research magazine.

ARS is the chief scientific research agency of the U.S. Department of Agriculture.