Author
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Fouss, James |
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Appelboom, Timothy |
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Submitted to: Environmental and Water Resources Institute World Congress Proceedings
Publication Type: Proceedings Publication Acceptance Date: 2/26/2006 Publication Date: 5/6/2006 Citation: Fouss, J.L., Appelboom, T.W. 2006. Combination of Drainage Water Management, Cover Cropping, and Wetland Diversion, as a Suite of BMPs to Reduce Nitrogen Loss from Cropland. [CD-ROM] Environmental and Water Resources Institute Conference World Environmental & Water Resources Congress Proceedings, Drainage BMPs for Nitrogen Management, May 21-26, 2006. Interpretive Summary: Conventional surface and subsurface drainage systems and common methods of applying fertilizer to cropland have resulted in increased fertilizer nitrate losses from agricultural fields to streams and surface waters. However, research results from several humid region locations over the past 20 years have shown that by controlling (reducing) subsurface drainage outflow during some periods of each year can significantly decrease nitrate losses by 40% to 50% carried in the drainage discharge from cropland. Other research has shown the benefit of planting a cover crop following harvest of the season’s crop, because the cover crop takes up nitrate in the soil and further reduces nitrate loss. In other research it has been shown that nitrate carried in stream flow can be significantly reduced by diverting the stream flow through wetland resource areas before routing it back into the main stream. This paper discusses the combination of these practices into a suite of Best Management Practices (BMPs) to reduce nitrate losses from cropland for improved stream water quality. Application of this suite of practices to cropland throughout the Mississippi River Basin could significantly reduce the amount of nitrate carried to the hypoxic zone in the Northern Gulf of Mexico. A cooperative action group, Drainage Water Management Systems Task Force (ADMS-TF), was formed in 2002 by employees of USDA’s Agricultural Research Service (ARS), Natural Resources Conservation Service (NRCS), Cooperative State Research, Education, and Extension Service (CSREES), and University research and extension partners to promote and implement drainage management (controlled drainage) on cropland to reduce nitrate losses in subsurface drainage discharge. The initial efforts of the Task Force, conducted cooperatively with drainage industry representatives, were in eight humid region Midwestern States of IA, IL, IN, OH, MI, MN, MO, & WI. BMPs of cover cropping and wetland diversion are also recommended as complementary practices to further reduce nitrate load in receiving streams and water bodies, and improve surface water quality. Retrofitting existing subsurface drainage systems for managed (controlled) operation is a major goal of the Task Force. The vast majority of all subsurface drains installed to date in the United States are conventional subsurface drains with gravity flow outlets to the full depth of the drain. An outlet control structure (e.g., overflow weir, valve, or pumped sump) can be used to convert the conventional installation to a drainage water management system. For new installations, the Task Force has recommended shallower drains, for example no deeper than 3.0 ft., thus reducing the potential for nitrate-N loss in subsurface drainage discharge if an outlet control is not installed. These same principals also apply to deep drainage ditches, and the potential benefits of managing (controlling) the outflow from ditch drainage systems are also being explored by Task Force members. Technical Abstract: Conventional surface and subsurface drainage practices and common crop fertilization methods have resulted in increased nitrate losses from agricultural fields to surface waters. However, research results from several humid region locations over the past 20 years have documented that controlled subsurface drainage can significantly reduce (40-50%) nitrate-N losses carried in drainage discharge from cropland. Other research has shown the benefit of post-harvest cover cropping as a nitrogen sink, which also reduces nitrate loss. Research has also shown that nitrate carried in stream flow can be significantly reduced by diverting the stream flow through wetland resource areas before routing it back into the main stream. This paper discusses the combination of these into a suite of Best Management Practices (BMPs) to reduce nitrate losses from cropland for improved stream water quality. Application of this suite of practices throughout the Mississippi River Basin could significantly reduce the amount of nitrate carried to the hypoxic zone in the Northern Gulf of Mexico. A cooperative action group, Drainage Water Management Systems Task Force (ADMS-TF), was formed in 2002 by employees of USDA’s Agricultural Research Service (ARS), Natural Resources Conservation Service (NRCS), Cooperative State Research, Education, and Extension Service (CSREES), and University research and extension partners to promote and implement drainage management (controlled drainage) on cropland to reduce nitrate losses in drainage discharge. The initial efforts of the Task Force, conducted cooperatively with drainage industry representatives, were in eight humid region Midwestern States of IA, IL, IN, OH, MI, MN, MO, & WI. BMPs of cover cropping and wetland diversion are also recommended as complementary practices to further reduce nitrate load in receiving waters and improve surface water quality. Retrofitting existing subsurface drainage systems for managed (controlled) operation is a major goal of the Task Force. The vast majority of all subsurface drains installed to date in the United States are conventional subsurface drains with gravity flow outlets to the full depth of the drain. An outlet control structure (e.g., overflow weir, valve, or pumped sump) can be used to convert it to a drainage water management system. For new installations, the Task Force has recommended shallower drains, for example no deeper than 3.0 ft., thus reducing the potential for nitrate-N loss in discharge if an outlet control is not installed. These same principals also apply to deep drainage ditches, and the potential benefits of managing (controlling) ditch drainage systems are also being explored by Task Force members. |
