Water table management studies, beginning with the Campus site and continuing through research at Unionville, show conclusively that water table management by controlled drainage and subirrigation is a viable method of supplementing natural rainfall to reduce the cost of agricultural production. Just as importantly, the Bannister and Unionville research suggested controlled drainage and subirrigation also reduces the loss of fertilizer nitrogen from the field without increasing the potential for runoff and erosion. However, it became clear that to fully understand these processes and use that knowledge to develop comprehensive water table management system guidelines, a study that allowed for intense, replicated, multi-disciplinary data collection with greater control of climatic variables was needed.
That project was initiated in 1991 on a privately owned field near Saginaw, Michigan. The Michigan Agricultural Experiment Station/USDA Subirrigation Rainshelter Project consists of 32 research plots, each 15 ft by 20 ft, and 3 field scale plots, each 10 acres in size. Rainfall on 24 of the small plots is controlled by two light-weight movable rainshelter buildings. Rainfall control allows the researchers to study dry, normal, and wet season conditions in a single growing season thus accelerating the learning process and transfer of knowledge to agricultural producers. Growing roots are observed and videotaped beneath 16 of the small plots via a reinforced concrete underground access structure adjacent to the sheltered plots. Water tables in each plot can be managed independently and all plots are instrumented to automatically measure depth to water table and subsurface drain flow and to collect water samples.
The project supports research by a multidisciplinary team of Michigan State University scientists from the Departments of Agricultural Engineering, Crop and Soil Sciences, Horticulture and Agricultural Economics. The research is conducted in close cooperation with the USDA Natural Resource Conservation Service, Cooperative Extension Service and Agricultural Research Service, the Michigan Chapter of the Land Improvement Contractors of America, the Michigan Departments of Agriculture and Environmental Quality and the Michigan Association of Conservation Districts, all of whom participated in the original planning for the project. The soil series at the site is Tappan (fine-loamy, mixed, calcareous, mesic-typic Haplaquolls), one of the most extensive and agriculturally productive soils in the "thumb" of Michigan. Tappan is very suitable for water table management.
Research objectives of the project are to: (1) evaluate the short and long term effect of water table management by subirrigation on the transport of agricultural chemicals, soil properties, surface and subsurface water and sediment movement, biological dynamics of the root zone soil system, economics of production of field crops and vegetables, and above and below ground plant development; (2) develop nutrient, pesticide, tillage, residue and water table management guidelines through field research and simulation modeling; and (3) share the research results with agricultural producers and their advisors.