Wetland Reservoir Subirrigation System

The WRSIS use of subirrigation was based on subirrigation/drainage systems research conducted by Drs. Norman R. Fausey and Richard Cooper of the USDA-Agricultural Research Service  cooperatively with The Ohio State University at the Ohio Agricultural Research and Development Center (OARDC) in Wooster and the Northwest Branch Station of OARDC in Hoytville, and also work conducted by Dr. Bud Belcher at Michigan State University.

Subirrigation

Subirrigation research has considered factors such as water table depth, row spacings, and cultivars. Soybean and corn yields at Wooster were on average 43% and 30% greater, respectively, for subirrigation/drainage systems compared to subsurface drainage alone. Soybean yields averaged 65 bu/ac and corn yields averaged 203 bu/ac with subirrigation over 6 years of research at Wooster. In addition, nitrate-N concentrations of drainage waters that outlet into streams decreased substantially.

Results of 5 years of subirrigation research at Hoytville (1992-1996) indicate a 21% increase in soybean yields and a 12% increase in corn yields over that produced from subsurface-drained cropland. Research results from Michigan State University complement those from the Ohio studies. In addition, seasonal wetland/subirrigation research at the Piketon Research and Extension Center is currently evaluating crop yield response and nitrogen cycling. Wetlands coupled with subirrigation systems are under study on 12 plots at the Ohio State's Piketon Research and Extension Center.

How the WRSIS works

During and after a rain, runoff and subsurface drainage waters flow into the wetland. A water control structure in the wetland is used to maintain a ponded water depth of one to two feet. Vegetation that grows in the water, on the bank, and in the adjacent habitat area helps to filter out sediment and nutrients from the flow. Water that flows from the wetland is pumped to the water supply reservoir for storage. Water in the reservoir can then be pumped to the subirrigation/subsurface drainage system to irrigate crops during the growing season. Subirrigation improves crop yields because crops receive a steady supply of water throughout the growing season. From the field, water drains back into the wetland, and the cycle starts again.

Simple water control structures and a pumping station help manage the water table in the field, and move water throughout the system.

	Wetland
Pump

Demonstration Sites  

Field demonstrations of WRSIS have been established to show how construction and management of wetlands coupled with subirrigation can increase farm incomes and improve the environment.

There are three demonstration projects in the Maumee River Watershed in northwestern Ohio - in Defiance, Van Wert, and Fulton counties. Each site contains a constructed wetland (installed on prior converted cropland), a water supply reservoir, and a field-scale corn/soybean production system where the crop is irrigated through a subirrigation/drainage system.

Defiance County The Defiance Agricultural Research Association is the site of 7 acres of subirrigated cropland, a 0.50 acre wetland (including water surface area and adjacent habitat) and a 0.5 acre water supply reservoir.

Van Wert County Property managed by the Farm Focus, in cooperation with the Marsh Foundation contains two 15-acre fields of subirrigated cropland, a 2.0 acre wetland (including water surface area and adjacent habitat) and a 2.0 acre water supply reservoir.

Fulton County The privately owned and operated Fred Shininger farm is the site of 20 acres of subirrigated cropland, 1.5 acres of wetland (including water surface area and adjacent habitat) and a 2.0 acre water supply reservoir.