S.R. Workman, N.R. Fausey, L.C. Brown, P. Bierman 2
The potential for contamiation of surgace and ground water from agricultural sources is a major concern. However current demands for agricultural commodities can only be met with agricultural production systems that use fertilizers and pesticides. A water quality remediation technique is being studied where lands are maintained in existing, productive agricultural management systems during the growing season and are converted to saturated, anaerobic wetlands during the non-growing period. The technique is termed a coupled wetland-agricultural ecosystem. Thirty-seven percent of the total cropland in the Midwest has received drainage improvements with much of this land having been created from previous wetlands. These lands are used primarily for corn and soybean production systems and could be easily and inexpensively transformed into winter wetlands for water quality remediation.
The quality of water discharged from replicated no-till corn/soybean agricultural management systems with "drainage only" water table management or a coupled wetland-agricultural ecosystem will be determined by monitoring daily subsurface and surface drainage discharge from each of 12 plots for nitrate-N, dissolved oxygen, and bromide. Bromide will be used as a conservative tracer to estimate potential nitrogen transport from the two systems. The remediation potential of anaerobic versus aerobic transformation processes will be characterized by monitoring soil aeration indicators, such as redox potential and dissolved oxygen content in the soil, soil-water, and surface and subsurface discharge. Nitrogen cycling, nitrogen pools, and denitrification potential will be determined quarterly.
