ARS | Publication request: Potential water quality impact of drainage water management in the Midwest USA

Submitted to: International Drainage Symposium
Publication Type: Proceedings
Publication Acceptance Date: June 13, 2010
Publication Date: June 17, 2010
Citation: Jaynes, D.B., Thorp, K.R., James, D.E. 2010. Potential water quality impact of drainage water management in the Midwest USA. International Drainage Symposium. ASABE Paper No. IDS-CSBE100084.

Interpretive Summary: Drainage water management (DWM) is a promising technology for reducing nitrate losses from artificially drained fields. Currently, little is known about the efficacy or cost effectiveness of the practice under Midwest U.S. conditions where artificial subsurface drainage is widely used. In this study, we extend the findings from our earlier study where we simulated the impact of DWM on reducing nitrate losses from drained fields across the Midwest using the ARS Root Zone Water Quality Model. We estimate that 4.8 million ha of land used to grow corn within the Midwest would be suitable for DWM. If DWM were adopted on all of this land, nitrate losses in drainage would be reduced by approximately 83 million kg ha-1 yr-1. Within just the Upper Mississippi River basin and Ohio/Tennessee River basins, DWM has the potential to reduce nitrate losses from drained fields by 52 million kg yr-1. This represents about a 6% reduction in nitrate loading to the Mississippi river and would be a substantial contribution to the target reduction of 45% likely required to reduce the hypoxic zone in the northern Gulf of Mexico to no more than 5,000 km2 each year. Lastly, we estimate that with the cost of control structures, redesign of new drainage systems, and payments to farmers to adjust the control structures to reduce nitrate losses, that the cost per kg of nitrate reduced in drainage water would be US$2.71 and very cost competitive with other practices for reducing nitrate loadings of surface waters. This research will be of interest to policy and decision makers in state and federal action agenies.

Technical Abstract: Drainage water management (DWM) is a promising technology for reducing nitrate losses from artificially drained fields. While there is an extensive history for the practice in North Carolina, little is known about the efficacy or cost effectiveness of the practice under Midwest U.S. conditions where artificial subsurface drainage is widely used. In an earlier study, we used a calibrated version of the Root Zone Water Quality Model (RZWQM) coupled with the Decision Support System for Agrotechnology Transfer (DSSAT) family of crop growth models to simulate the impact of DWM on reducing nitrate losses from drained fields across the Midwest. In this study, we use assorted spatial databases to estimate that 4.8 million ha of land used to grow corn within the Midwest would be suitable for DWM. If DWM were adopted on all of this land, nitrate losses in drainage would be reduced by approximately 83 million kg ha-1 yr-1. Within just the Upper Mississippi River basin and Ohio/Tennessee River basins, DWM has the potential to reduce nitrate losses from drained fields by 52 million kg yr-1. We estimate that with the cost of control structures, redesign of new drainage systems, and payments to farmers to adjust the control structures to reduce nitrate losses, that the cost per kg of nitrate reduced in drainage water for DWM would be US$2.71.