Crop production response to conservation practices and sustainable intensification in a corn-soybean cropping system

Authors: O'Brien, Peter; Emmett, Bryan; Kovar, John; Malone, Robert - Rob; CAMBARDELLA, CYNTHIA - Retired ARS Employee; JAYNES, DANIEL - Retired ARS Employee; KASPAR, THOMAS - Retired ARS Employee; KOHLER, KEITH - Retired ARS Employee; MOORMAN, THOMAS - Retired ARS Employee; PARKIN, TIMOTHY - Retired ARS Employee

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/10/2021
Publication Date: 11/10/2021
Citation: O'Brien, P.L., Emmett, B.D., Kovar, J.L., Malone, R.W., Cambardella, C.A., Jaynes, D.B., Kaspar, T.C., Kohler, K.A., Moorman, T.B., Parkin, T.B. 2021. Crop production response to conservation practices and sustainable intensification in a corn-soybean cropping system [abstract]. ASA-CSSA-SSSA Annual Meeting. Paper no. 138076.

Interpretive Summary:

Technical Abstract: Highly productive corn (Zea mays L.)-soybean (Glycine max (L.) Merr.) based agroecosystems across the US Midwest are currently under competing pressures to increase production to meet growing demand for food and fuel as well as reduce their environmental footprint. Multiple management practices have the potential to address these goals, including conservation tillage, adaptive nutrient management, cover cropping, and alternative cropping system strategies. We initiated an experiment in 2016 in central Iowa to compare a basic practice treatment of a fixed-rate N application and fall chisel plow (BP) with three alternative management system treatments. Each alternative treatment received split fertilizer N application with sidedress N based on the Late Spring Nitrate Test, and were managed as: ii) no tillage (NT); iii) no tillage with rye cover crop (RC); and iv) winter-camelina (Camelina sativa (L.) Crantz) relay crop preceding soybean (WC). After three rotations, we found that corn yields were higher in the BP (13.2 Mg ha-1) than both the NT (11.5 Mg ha-1) and RC (11.1 Mg ha-1). However, the BP was only significantly higher than WC in 2016. Soybean yields were between 15-25% lower in the WC compared to the other three treatments in 2017 but not in 2019, indicating that the relay-cropping system can result in reduced soybean yields. Winter camelina yields were relatively low (0.7 – 1.0 Mg ha-1), but the sum of soybean and camelina yields in WC led to the highest production of any treatment during the soybean phase. Rye cover crop reduced nitrate losses compared to BP, but nitrate and N2O losses remained high in the WC, likely due to increased N application and light tillage. These findings suggest that implementing multiple complementary management practices may be the best path to navigate the tradeoffs between increasing crop production and reducing environmental impacts.