|YOUSSEF, MOHAMED - North Carolina State University|
|ABDELBAKI, AHMED - El-Fayoum University|
|NEGM, LAMYAA - North Carolina State University|
|SKAGGS, R.WAYNE - North Carolina State University|
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2017
Publication Date: 1/15/2018
Citation: Youssef, M.A., Abdelbaki, A.M., Negm, L.M., Skaggs, R., Thorp, K.R., Jaynes, D.B. 2018. DRAINMOD-simulated performance of drainage water management across the U.S. Midwest. Transactions of the ASABE. 197:54-66.
Interpretive Summary: Excessive levels of nitrate in surface water bodies have had severe ecologic and economic impacts throughout the drainage basin of the Mississippi River and have caused problems as far south as the Gulf of Mexico, where hypoxia threatens commercial and recreational fisheries. Many scientific studies have found a link between excessive surface water nitrate levels and movement of nitrate through agricultural drainage systems, which have been used for 150 years throughout the midwestern United States to improve the agricultural productivity of the region. Drainage water management is a new technology that promises to reduce losses of nitrate from agricultural fields by regulating the flow of water through the drainage systems. Our study utilized an agricultural systems model to simulate the performance of drainage water management over 25 years of meteorological measurements at 48 different locations across the Midwest. We used the simulation results to assess the efficacy of using drainage water management to reduce nitrate loss across the region. We also assessed the potential negative impacts of drainage water management on other aspects of an agricultural system, such as increased runoff and increased loss of nitrate to groundwater. Results of this study will be useful for researchers and practitioners who want to implement drainage water management practices in the Midwest. In particular, the findings will benefit the Agricultural Drainage Management Systems (ADMS) Task Force, which is a cooperative effort among several universities, government agencies, and agricultural drainage companies to research, implement, and promote the use of improved agricultural drainage systems for decreasing losses of nitrate from agricultural fields. Our study evaluated drainage water management in eight states across the Midwest, including Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio, and Wisconsin, which is also the current focus area of the ADMS Task Force.
Technical Abstract: Drainage water management (DWM) is currently being proposed as a best management practice for reducing nutrient export from drained cropland in the U.S. Midwest to the Mississippi River and the Gulf of Mexico. The effectiveness of the practice in the Midwest has not been well documented. We conducted a simulation study using the hydrologic model, DRAINMOD, and the carbon and nitrogen model, DRAINMOD-N II, to evaluate the performance of DWM across the U.S. Midwest. Thorp et al (2008), used the RZWQM-DSSAT models, calibrated for a corn and soybean production system on a subsurface drained IOWA soil, to simulate the performance of DWM using 25-years of climatological data for 48 locations across the Midwest. We used DRAINMOD-DRAINMOD-N II models, calibrated for the same conditions, to simulate the performance of DWM at the same 48 locations. Simulation results showed that DWM reduced annual subsurface drainage by 30% and annual N drainage losses by 32%, on average over the 48 sites. DWM was most effective in reducing drain flow and N drainage losses for the south and southeast locations. Highest simulated reductions in drain flow (45%) and N drainage losses (47%) occurred in Memphis, Tennessee. DWM was least effective for the northwest locations. Lowest simulated reduction in drain flow of 19% occurred in both Sioux City, Iowa and Sioux Falls, South Dakota. Lowest simulated reduction in N drainage loss of 12% occurred in Fargo, North Dakota. RZWQM-DSSAT showed a similar trend but predicted that the implementation of DWM will lead to substantially higher reductions in both drain flow (35-68%) and N drainage losses (33-58%). DRAINMOD-simulated crop yield indicated a slight increase of the regional average of corn and soybean yields because of implementing DWM (less than 1.5%), suggesting that the yield benefits of DWM cannot solely be used to effectively promote the practice among producers.