|KLADIVKO, EILEEN - Purdue University|
|Malone, Robert - Rob|
|SINGER, JEREMY - Former ARS Employee|
|MORIN, XENIA - Rutgers University|
|SEARCHINGER, TIMOTHY - Princeton University|
Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2014
Publication Date: 7/1/2014
Citation: Kladivko, E.J., Kaspar, T.C., Jaynes, D.B., Malone, R.W., Singer, J., Morin, X.K., Searchinger, T. 2014. Cover crops in the upper midwestern United States: Potential adoption and reduction of nitrate leaching in the Mississippi River Basin. Journal of Soil and Water Conservation. 69(4):279-291. DOI: 10.2489/jswc.69.4.279.
Interpretive Summary: Nitrate losses from agricultural lands in the Midwest flow into the Mississippi River Basin and contribute significantly to hypoxia in the Gulf of Mexico. Previous work has shown that cover crops can reduce loadings, but adoption rates are low, and the potential adoption and impact are currently unknown. This paper analyzes the factors affecting ease of cover crop use and estimates the potential adoption and impact on nitrate losses in five states that are important for corn and soybean production and contribute nearly one-half of the total nitrate found in the Mississippi River that reaches the Gulf of Mexico. This study showed that in the ten counties used for the analysis that cover crop adoption depends on the combinations of crop rotation, tillage systems, and timing of tillage and that potential cover crop adoption ranged from 53 to 85%. Calculations of potential nitrate leaching loss reductions based on model predictions estimate that nitrate losses could be reduced in these 10 counties from a high of 40% in Indiana and Ohio to a low of 13% in Minnesota. These estimates show that cover crops could have a significant impact on water quality in the Mississippi River Basin and that increasing adoption of cover crop will be facilitated by a shift of tillage practices from fall to spring and from more intensive tillage system to mulch till, strip till, or no-till. These results can be used by policy makers and action agencies to encourage adoption of cover crops through incentive and educations programs to producers concerning both tillage systems and cover crops.
Technical Abstract: Nitrate losses from agricultural lands in the Midwest flow into the Mississippi River Basin (MRB) and contribute significantly to hypoxia in the Gulf of Mexico. Previous work has shown that cover crops can reduce loadings, but adoption rates are low, and the potential impact is currently unknown. This paper provides the first integrated analysis of the factors affecting ease of cover crop use and relative benefits to water quality across the five–state region of Ohio, Indiana, Illinois, Iowa, and Minnesota in the upper Midwest MRB. Two agricultural counties were selected in each of the five states, and case studies were performed using optimistic scenarios of potential fall-planted cover crop adoption based on cash crop and tillage systems. These 10 case studies predicted that an estimated 52 to 85% of the crop acres could integrate cover crops into their cropping systems. Calculations of potential nitrate-N leaching reductions from cover crop adoption based on adoption of winter rye or spring oats on these acres ranged from a high of around 40% in some counties in Indiana and Ohio, to a low of 13% in one of the Minnesota counties. These adoption rates would in some cases require shifts from fall to spring tillage, but could be higher with broader adoption of no-till and mulch till. These predictions suggest that cover crop adoption would have a beneficial impact on water quality in the MRB and would contribute greatly towards meeting the national goal of significant reduction in nitrate-N load entering the Gulf.