Estimating Crop Water Needs and Agronomic Benefits of Drainage Water Reuse and Subirrigation in the Red River Valley, Minnesota.

Drainage water reuse through subirrigation is gaining increasing interest in the Red River Valley in Northwest Minnesota and other areas of the Corn Belt. When installed and managed properly, these practices may help increase agricultural production, minimize losses of nutrients and help mitigate downstream flood conditions. There is a need, however, to quantify the yield impacts of drainage water reuse to inform system performance and economic aspects of installing subsurface drainage systems to accommodate subirrigation. The objectives of this study are to estimate the net irrigation requirements and potential yield benefits for corn and soybean in the Red River Valley, Minnesota. Meteorological information from the NDAWN weather network maintained by North Dakota State University is used to estimate crop water requirements. Subsurface drainage plots managed by the Minnesota Discovery Farm network and drainage demonstration plots managed by the Minnesota Department of Agriculture are used to estimate water volumes available for storage and reuse. A crop simulation model is used to simulate yield impacts of different levels of supplemental irrigation scenarios. Knowledge of irrigation water supply, irrigation requirements and yield impacts are important to help determine the feasibility and design requirements of drainage water reuse systems.