Expect to hear the term "drainage water management” frequently in the next few years. Research underway at 20 sites in five Midwestern states indicates the practice will pay off for farmers, and also for the Gulf of Mexico, where it will help reduce hypoxia.
Hypoxia is a condition of low oxygen levels, which make life difficult or impossible for sea creatures. Nitrate escaping from farm fields into the Gulf appears to be one of the causes; the excess nutrients lead to algae blooms, which deplete the water's nitrogen content.
Drainage water management involves placing a control structure just upstream of the outlet of a patterned tile system. Using the control structure, growers can minimize outflow during the winter, drain soil to a targeted depth for field work and then rebuild soil moisture reserves for crop use during the growing season.
Studies indicate drainage water management can reduce the amount of nitrate leaving a field from about 15% to 75%, depending on location, climate, soil type and cropping system. The nitrate load is reduced three ways: reduced total outflow; denitrification within the soil profile; and deep seepage. Some of the water that is not drained does become surface runoff; but nitrate concentrations are considerably lower than in tile water.
The concept is so promising that drainage water management will be eligible for funding under the Environmental Quality Incentives Program (EQIP) in the new farm bill, says Leonard Binstock, executive director of the Agricultural Drainage Management Coalition (ADMC). "We also expect drainage water management to be included in the new Conservation Stewardship Program, after the rules are written,” he says. "That would make an annual payment available to producers for managing their systems.”
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