Submitted to: ASAE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 7/1/2005
Publication Date: 7/20/2005
Citation: Nangia, V., Gowda, P., Mulla, D.J., Sands, G. 2005. Modeling nitrate-nitrogen losses in response to tile drain depth and spacing in a cold climate. In: American Society of Agricultural Engineers Annual International Meeting Technical Papers, July 17-20, 2005, Tampa, Florida. Paper Number 052022. CDROM.
Interpretive Summary: Subsurface tile drainage systems enhance crop yield on poorly drained but highly productive soils by improving aeration, availability of nutrients, and allowing timely farm operations. It also increases decreases surface runoff and soil erosion. Consequently, it has become a routine practice over large areas of the Midwest U.S. However numerous studies have shown that the presence of tile drainage systems increase nitrate losses from fields through subsurface tile drainage. In this study, we evaluated the effects of tile spacing and depth on nitrate losses using a water quality simulation model. For this purpose, the ADAPT model was calibrated and validated for water quality data from two tile drained fields in Nicollet County, southeastern Minnesota. Using the calibrated model, long-term simulations were made to account for climatic variability. Modeling results indicate that increase in spacing and decrease in depth of tile drains reduces the tile drainage and NO3 N losses, and can serve as a remedy to the excess NO3 N loads in the Gulf of Mexico.
Technical Abstract: The Agricultural Drainage and Pesticide Transport (ADAPT) model was used to evaluate the effects of tile drain spacing and depth on NO3-N losses in southeastern Minnesota. The model was calibrated and validated using 4 years of monthly flow and nitrate loss data from two tile drained fields (11 and 9.3 ha) in Nicollet County. Half the monitoring data from the 11 ha field were used for calibration and half for validation of the model. The model was also validated using independent monitoring data from the 9.3 ha field. For the calibration period on the 11 ha field, the model predicted mean monthly tile drainage and NO3-N losses of 141.5 m3/day and 5.2 kg/ha, respectively, against measured tile drainage (126.2 m3/day) and NO3-N losses (4.5 kg/ha). For validation, the predicted mean monthly tile drainage and NO3-N losses were 131.7 m3/day and 4.4 kg/ha, respectively, against measured tile drainage and NO3-N losses of 80.4 m3/day and 3.0 kg/ha, respectively. Similar validation results were found with 9.3 ha field. Long-term simulations were made for a wide range of climatic conditions (1954-2003) to evaluate the effects of drain spacing and drain depth on tile drainage and NO3-N losses. Simulations results indicate that increasing spacing and decreasing depth of tile drains reduces the tile drainage and NO3-N losses and can serve as a remedy to the excess NO3-N losses.