Simulated impacts of winter rye cover crop on continuous maize yield and soil parameters

Authors: Birru, Girma; SHIFERAW, ANDUALEM - University Of Nebraska; TADESSE, TSEGAYE - University Of Nebraska; Schmer, Marty; Jin, Virginia; WARDLOW, BRIAN - University Of Nebraska; KOEHLER-COLE, KATJA - University Of Nebraska; AWAD, TALA - University Of Nebraska; Beebout, Sarah; Tsegaye, Teferi; Kharel, Tulsi

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2023
Publication Date: 1/28/2023
Citation: Birru, G.A., Shiferaw, A., Tadesse, T., Schmer, M.R., Jin, V.L., Wardlow, B., Koehler-Cole, K., Awad, T., Beebout, S.E., Tsegaye, T.D., Kharel, T.P. 2023. Simulated impacts of winter rye cover crop on continuous maize yield and soil parameters. Agronomy Journal. 115(3):1114-1130. https://doi.org/10.1002/agj2.21291.
DOI: https://doi.org/10.1002/agj2.21291

Interpretive Summary: Cover crops provide numerous ecosystem services such as improving soil health, reducing nutrient loss, increasing productivity, and other environmental benefits. However, there have been isolated reports of grain yield reductions following cover crops. This has reduced the likelihood of farmers adopting cover crops. This is partly attributed to the gap in current state of knowledge in cover crops and its interaction with main crop production under different biophysical conditions. Decision Support System for Agrotechnology Transfer (DSSAT) model was used to evaluate the long-term impact of cereal rye on maize yield, soil organic carbon, N leaching, soil water and drainage at two locations in Nebraska (ENREC and SCAL) with contrasting climate, soil and crop managements conditions. Model calibration and validation was made on one pioneer corn hybrid (P1197) with cumulative relative maturity of 111 days and one cereal rye cultivar (Elbon) respectively using experimental data collected over several locations. Comparison of 30-year DSSAT simulation of continuous maize with (CC) and without (NCC) cereal rye cover crop showed no significant difference on maize yield and SOC over the two locations and irrigated management condition. However, rye cover crop has resulted in a significant reduction in nitrate leaching associated with a reduction in subsurface at central and eastern Nebraska. Cover crop biomass was also increased significantly with delay of termination dates by only 5 and 10 days without compromising maize yields. Delaying spring termination by approximately 5 days produced 39% more biomass and delay by another 5 days produced 93% more biomass. The results of this simulation-based study has demonstrated that DSSAT can be a valuable tool to investigate the outcome of adopting cover crops in continuous maize system across sites and crop management conditions. Thus, the study should be extended over more sites with diverse environmental and management scenarios to identify a combination of practices that can result in win–win scenarios for cover crop integration.

Technical Abstract: In this study, Decision Support System for Agrotechnology Transfer (DSSAT) model was used to evaluate the long-term impact of cereal rye on maize yield, soil organic carbon (SOC), nitrate leaching, soil water and drainage for a range of climate, soil, and irrigation management in Eastern and Central Nebraska. A 30-year (1991-2020) simulation showed no difference in maize yield and SOC between Cover Crop (CC) and No-Cover Crop (NCC) treatments at both sites under irrigated and rainfed conditions. However, CC resulted in reduction of N loss by up to 48% at the Eastern Nebraska Research and Extension Center (ENREC) and 24% at South Central Agricultural Laboratory (SCAL) under irrigation. Cereal rye has no significant effect on total soil water but, a significant reduction in cumulative sub-surface drainage of 44% was determined at both sites. This study has shown the possible effect of cover crop on maize crop yield and soil properties over different regions in Nebraska. Future research extending the scope and geographic area is needed to test and quantify possible impacts of multiple cover crops species under diverse management and biophysical conditions.