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ARS Home » Research » Publications at this Location » Publication #83901
Title: NITRATES IN RUNOFF AND LEACHATE FROM CONTROLLED-WATER-TABLE PLOTS ON A MISSISSIPPI RIVER ALLUVIAL SOIL

Author
item Willis, Guye
item Southwick Jr, Lloyd
item Fouss, James

Submitted to: Irrigation and Drainage International Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/10/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Nitrate movement into surface and ground waters has become a concern for both environmental (algal blooms) and health (blue baby syndrome) reasons. High nitrate concentrations in water resources are more likely in areas with high rainfall/runoff and shallow water tables. Since nitrates are required for plant growth, and are ususally added to soil as inorganic commercial fertilizers or organic amendments (e.g., manures), it is important to develop technology that allows nitrogen fertilization sufficient for profitable crop production, and that reduces the potential for nitrate loss from crop lands. A water management system for controlling water table depth was evaluated for corn grown on shallow-water-table soils in Louisiana. Water management treatments included, (1) surface drainage only, (2) conventional subsurface drainage at about 40 inches or deeper below the soil surface, (3) a water table maintained at 18 inches below the soil surface, and (4) a water table maintained at 30 inches below the soil surface. Nitrate losses in surface runoff from treatments 2, 3, and 4 ranged from 15% to 30% less than for treatment 1. Losses in subsurface drainage from treatments 2, 3, and 4 were small (less than 3 pounds per acre). The results suggest that water table control is a promising tool for reducing nitrate losses from shallow water table soils to surface and subsurface water resources.

Technical Abstract: Nitrate movement into surface and ground water has become a concern for both environmental (eutrophication) and health (methemoglobinemia) reasons. Controlled subdrainage and subirrigation have been used to reduce nitrate losses in runoff and drain outflow in humid Midwest and Southeast. N-fertilizers (224 kg N/ha) were applied to corn plots instrumented for water table control on silty clay loam soil in Louisiana. Data for 1996 suggest that water table control is a promising tool for managing soil water to reduce nitrate loads in surface and ground waters on high-water-table soils.