Does nitrogen management in winter wheat affect its yield and nitrate-N leaching in a wheat-soybean double cropping system?

Conventional corn (Zea mays L.)-soybean (Glycine max L.) rotation contributes to nitrate-N and phosphate leaching to waterbodies causing water quality concerns. Two strategies that could minimize N and P losses include (i) incorporating winter rye (Secale cereale L.) (WR) as a cover crop to capture residual nutrients or (ii) intensifying the corn-soybean rotation with winter wheat (WW) (Triticum aestivum L.) (Double cropping). Double cropping WW at a right N management could increase farm profit and provide incentives for adoption as well. A trial was established at two sites (Carbondale, and Belleville, IL) to evaluate soybean and overall cash crop performance along with nitrate-N and phosphate losses in a single season [soybean following a no-cover crop control vs. WR as compared to three double cropping scenarios (low, medium, and high intensity N management of WW prior to soybean). The results indicated that double cropping decreased soybean yield regardless of N management intensity during the previous WW. Nitrogen addition to WW resulted in increased nitrate-N leaching during the WW phase but at medium and high N intensity scenarios, decreased the nitrate-N leaching during the following soybean phase and overall WW-soybean growing seasons suggesting double cropping could minimize N losses and provide farm profit.