Impact of Rye Cover Crop On Nitrate-Nitrogen Concentrations in Subsurface Drainage in Iowa.

Nitrate-nitrogen (NO₃-N) export from agricultural fields via drainage waters is a major factor in nonpoint source pollution of surface water in Midwestern U.S.  Growing winter cover crop is one of the strategies that has the potential to reduce NO₃-N losses from tile drained soils. Two studies in Iowa are investigating the impact of rye cover crop on NO₃-N concentrations in subsurface drainage under a corn-soybean rotation system.  These studies are examining the performance of rye cover crop in reducing NO₃-N concentrations and export under different tillage systems (conventional tillage and no-till).  Results from both studies indicate that cover crop greatly reduces NO₃-N concentrations regardless of tillage system and crop type. Crop yields with cover crop are comparable to or slightly lower than those without cover crop. These results indicate that rye cover crop has the potential to reduce NO₃-N export from rowcrop agriculture.  One of these studies is part of the Cropping Systems Coordinated Agricultural Project (CSCAP).