Evaluation of DRAINMOD-N2 for Ohio Conditions

Conventional subsurface drainage has been widely used in the Midwestern region of the United States to enhance crop production. However, it is also a primary contributor of nitrate-nitrogen in surface water. Agricultural Drainage Water Management (DWM) has been identified as a best management practice in reducing soluble nutrient pollution. Water table control structures can be managed to conserve and recharge soil water during fallow seasons, help reduce nitrate-N loads, and possibly provide additional soil water to meet crop water needs during the crop season. Based on USDA-ARS research in northwestern Ohio that shows drainage volume reductions of 40%, and nitrate-N load reductions of more than 45%, we are implementing DWM demonstrations in selected Ohio watersheds. Our study is evaluating the effect of DWM at the field scale based on field studies and model simulation. DRAINMOD-NII has been calibrated and validated for conditions in North Carolina and several Midwestern states, and has been shown to be effective in modeling drainage flows and nitrate loads. Plot data from northwestern and southern Ohio will be used to calibrate and validate DRAINMOD NII for Ohio conditions. The validated model will be used to simulate drain flows at four of the demonstration sites, comparing the DWM system to a typical subsurface drainage system.