Evaluation of DRAINMOD for Potato Crop under Cold Conditions in the Canadian Prairies

Abstract

<abstract> <b><sc>Abstract.</sc></b> Subsurface drainage is used for removing excess water in poorly drained agricultural lands. The performance of subsurface drainage systems varies depending on the soil, crop, and climatic factors. Field evaluation of drainage systems under different field conditions can be costly and time-consuming, necessitating the use of computer models for the design and the evaluation of long-term performance. DRAINMOD is a widely used model for simulating shallow groundwater hydrology in poorly or artificially drained farmlands. The objective of this study was to evaluate DRAINMOD for simulating the hydrology and potato (Solanum tuberosum) crop yield under cold climatic conditions. Data were obtained from a field study that was conducted during 2010 to 2012 in southern Manitoba in a fine sandy loam soil. DRAINMOD calibration and validation were done using data from subsurface-drained plots with drain spacing of 15 m and average drain depth of 1.06 m. Daily subsurface drainage flow, weather parameters, irrigation rate, and water table depth were measured onsite. Subsurface drainage and water table depth were the main variables that were evaluated with DRAINMOD simulations. In general, DRAINMOD predictions of subsurface drainage flow and water table depth were in good agreement with observed values on a daily basis. Statistical parameters showed that DRAINMOD predictions of daily water table depth were more accurate than model predictions of daily drainage flow. The Nash-Sutcliffe modeling efficiency values were in the range of 0.69 to 0.76 for drainage flow and 0.57 to 0.94 for water table depth. The mean absolute error was between 70 and 134 mm for water table depth predictions and between 0.42 and 0.44 mm for drainage flow predictions. The root mean square error was 0.77 to 1.14 mm for drainage flow and 83 to 147 mm for water table depth. DRAINMOD overpredicted potato yield by up to 1%. Based on the results, it is concluded that DRAINMOD predictions of the shallow groundwater hydrology under cold climate were satisfactory.