|Fausey, Norman - Norm|
Submitted to: International Drainage Symposium
Publication Type: Proceedings
Publication Acceptance Date: 3/8/1998
Publication Date: N/A
Technical Abstract: A series of laboratory experiments was conducted on Ohio and Indiana soils to investigate the effects of water table management on solute transport in intact soil columns, and selected columns with artificial macropores. Studies were conducted on Blount silt loam, Brookston silty clay loam, Rossburg and Huntington silt and sandy loam, and Clermont silt loam. Water rtable management strategies included controlled and conventional drainage, with various depths and durations. Agrichemicals evaluated included nitrate and a suite of herbicides, and the tracer bromide. Results from these studies contain parallels, as well as inconsistencies. Over all studies and column conditions, water table depth influenced the movement of all solutes studied, in particular bromide and nitrate. Comparison of bromide to nitrate breakthrough indicated that as depth to water table increased, amount of nitrate discharged decreased, suggesting nitrate losses through denitrification. Recovered bromide exceeded 95% for all studies, while recovery of nitrate ranged between 20 and 90%. Companion column N-gases studies verified that nitrification and denitrification could occur under these conditions. For herbicides, as depth to water table decreased, amount of herbicide recovered increased with recovery ranging between 0.1 and 20%. Free drainage conditions enhanced nitrate losses and decreased herbicide losses in column drainage waters. High water table conditions enhanced herbicide losses and decreased nitrate losses in column drainage waters. These results suggest that water table management strategies must be evaluated and designed for site specific conditions, focused on both water quality and production objectives. For some conditions, tradeoffs in benefits must be considered.