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United States Department of Agriculture

Agricultural Research Service

Title: Predicting Subsurface Drainage, Corn Yield, and Nitrate Nitrogen Losses with Drainmod-N

Authors
item Zhao, Suling - RESOURCE 21
item Gupta, Satish - UNIVERSITY OF MINNESOTA
item Huggins, David
item Moncrief, John - UNIVERSITY OF MINNESOTA

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 31, 2000
Publication Date: N/A

Interpretive Summary: Nitrate nitrogen from artificially drained soils of the upper Midwest United States is finding its way to the Mississippi River and then to the Gulf of Mexico. There is some concern that this nitrate is causing hypoxia in the Gulf of Mexico. The DRAINMOD-N model was used to evaluate the long- term impact of N application rate and subsurface drain spacing on corn yield and nitrate losses. The model was calibrated and then validated against long-term field data from southwestern Minnesota. A twenty-four year simulation showed that climate plays a major role in determining drainage, yield, and nitrate losses from a moderately well-drained Normania clay loam soil under continuous corn. April to August rainfall accounted for 82 percent of the variation in drainage and 66% of the variation in nitrate losses during the growing season. Corn yield significantly increased when drain spacing was changed from 56 to 28-m but much less increased when changing from 28 to 14-m. During the growing season, drain spacing had little impact on nitrate losses from this soil. Cost/benefit analysis showed that 28-m drain spacing was a good design criterion for this soil. For a given drain spacing, an increase in N application rate significantly increased nitrate losses through drainage. We conclude that efforts to reduce nitrate losses from artificially drained soils of the upper Mid-west United States should concentrate on identifying N management strategies that increase N use efficiency.

Technical Abstract: Nitrate-N from artificially drained soils of the upper Midwest United States is finding its way to the Mississippi River and then to the Gulf of Mexico. There is some concern that this nitrate-N is causing hypoxia in the Gulf of Mexico. The DRAINMOD-N model was used to evaluate the long- term impact of N application rate and drain spacing on corn (Zea mays L.) yield and nitrate-N losses. Prior to evaluation, the model was calibrated and then validated against long-term field data from southwestern Minnesota. A twenty four years simulation showed that climate plays a major role in determining drainage, yield, and nitrate-N losses from a moderately well drained Normania clay loam (fine-loamy, mixed, mesic Aquic Haplustoll) soil under continuous corn. April to August rainfall accounted for 82 percent of the variation in drainage and 66% of the variation in nitrate-N losses during the growing season. Corn yield significantly increased when drain spacing was changed from 56 to 28-m but much less increase when changing from 28 to 14-m. During the growing season, drain spacing had little impact on nitrate-N losses from this soil. Cost/benefit analysis showed that 28-m drain spacing was a good design criterion for this soil. For a given drain spacing, an increase in N application rate significantly increased nitrate-N losses through drainage. We conclude that efforts to reduce nitrate-N losses from artificially drained soils of the upper Mid-west United States should concentrate on identifying N management strategies that increase N use efficiency.

Last Modified: 7/27/2014
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