Bioreactors Eligible for EQIP Assistance

October 22, 2009

Denitrifying bioreactors are now eligible for technical and financial assistance through the Environmental Quality Incentives Program (EQIP. These underground structures are filled with a carbon source, such as wood chips, and intercept and treat tile water flow and reduce nitrate levels in water leaving agricultural land.

USDA’s Natural Resources Conservation Service (NRCS) recently drafted an interim conservation practice standard in Iowa for bioreactors, which are designed to improve water quality in sites where there is a need to reduce the concentration of nitrate-nitrogen of subsurface drain flow or groundwater.

Administered by NRCS, EQIP offers farmers financial and technical assistance to install or implement structural and management practices on eligible agricultural land. In fiscal year 2009, NRCS provided more than $20 million in financial assistance to Iowa farmers through EQIP.

The Iowa Soybean Association (ISA) is providing technical assistance to groups and landowners in watersheds that need a reduction in nutrient loading. Roger Wolf, director of environmental programs for ISA, says the bioreactor is one practice to consider. ISA partnered with Agriculture’s Clean Water Alliance, the Sand County Foundation, Iowa State University and others for a series of bioreactor installation demonstration projects for interested farmers. Wolf says bioreactors are relatively inexpensive and easy to construct, take little or no land out of production and require little maintenance. “There are no adverse effects on crop production, and they can be designed to not restrict drainage,” he said.

Basic Features

• Bioreactors are generally located on the edge of a field to reduce compaction from traffic and interference with field operations.
• The size and configuration of bioreactors is determined by desired flow rate, permeability of the carbon source (wood chips), and the desired hydraulic retention time (the time it takes for wood chips to metabolize nitrate into gas).
• A water control structure will divert tile flow to the bioreactor. However, high flows bypass the bioreactor, thus maintaining normal field drainage.
• A geotextile lining is used for the top of the bioreactor to prevent soil particles from blending with the wood chips.

Wolf says early research shows that a bioreactor can remove 25 to 35 percent of nitrate in tile line water, which is particularly important in north-central Iowa where nitrate levels in tile lines are among the highest in the country. “Excess nitrogen and phosphorus cause havoc to our aquatic systems,” says Wolf. “Nutrients in the water cause algae growth and when algae dies off it consumes oxygen in the water.”

Bioreactors will cost an estimated $7,000-$10,000, which includes excavation, wood chips and a control structure. A major cost factor is size, which will depend on tile line size, slope, and time needed to treat nitrate. Bioreactors will be designed to work for at least 10 years, but Keegan Kult, watershed management specialist with the Iowa Soybean Association, says he expects bioreactors to function well for about 15 years.

Webster County farmer Gary Nelson is very encouraged by the potential benefits of bioreactors. “I see this as being proactive,” he says, “instead of waiting until the government restricts the amount of nitrogen we can apply.” There is a bioreactor demonstration site on the Ann Smeltzer Charitable Trust Farm near Otho, which Nelson rents.

Mississippi River Basin Initiative (MRBI)

The federal government is currently taking action in a new 12-state NRCS initiative to reduce nutrient loading in the Mississippi River Basin. Denitrifying bioreactors will be a core trapping conservation practice in the newly developed Mississippi River Basin Healthy Watersheds Initiative (MRBI), which includes Iowa.

NRCS developed MRBI to help producers in selected watersheds voluntarily implement conservation practices that avoid, control, and trap nutrient runoff, improve wildlife habitat, and maintain agricultural productivity. NRCS will provide producers assistance with a system of practices that will control erosion, improve soil quality, and provide wildlife habitat while managing runoff and drainage water for improved water quality.

NRCS will offer this Initiative in fiscal years 2010 through 2013, dedicating at least $80 million in financial assistance each fiscal year. This is in addition to regular NRCS program funding. Selected Iowa watersheds will be announced later this fall. 

For more information about denitrifying bioreactors and EQIP, visit your local NRCS office. More details about MRBI are available at www.nrcs.usda.gov.

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