|Water Quality and Water Management|
The export of nitrogen, phosphorus and sediment from farm fields to surface waters is a serious problem in the Upper Midwestern U.S. Research by us and by others suggests that one effective means for reducing these losses is to maintain vegetative cover on the landscape throughout the year, which is a focus of our cover crop and living mulch research, described elsewhere on this site. However, both our measurements and modeling indicate that these practices can negatively affect corn and soybean yields, primarily due to their use of additional water. The irony of this is that corn and soybean yields in the region are also frequently affected by excess water – in fact, we have found that 75% of crop insurance payments for corn and soybean yield losses in the 5-state central corn belt (MN, IA, IL, IN, OH) over the period 2000-2011 were water-related, and the losses to drought and excess water were roughly equal, approximately $2.5 billion each. We have argued Baker et al. 2012. (Water Resour. Res.) that innovative water management practices that store excess water for use in supplemental irrigation during transient drought could stabilize yields, reduce crop insurance payouts, and foster the use of otherwise risky cropping practices like cover crops and companion cropping that have known water quality benefits.