Cover crop performance under a changing climate in continuous corn system over Nebraska

Authors: Birru, Girma; SHIFERAW, ANDUALEM - University Of Nebraska; TADESSE, TSEGAYE - University Of Nebraska; WARDLOW, BRIAN - University Of Nebraska; Jin, Virginia; Schmer, Marty; AWADA, TALA - University Of Nebraska; Kharel, Tulsi; IQBAL, JAVAD - University Of Nebraska

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2023
Publication Date: 10/27/2023
Citation: Birru, G.A., Shiferaw, A., Tadesse, T., Wardlow, B., Jin, V.L., Schmer, M.R., Awada, T., Kharel, T.P., Iqbal, J. 2023. Cover crop performance under a changing climate in continuous corn system over Nebraska. Environmental Quality. 53(1):66-67. https://doi.org/10.1002/jeq2.20526.
DOI: https://doi.org/10.1002/jeq2.20526

Interpretive Summary: Cover crops (CC) can provide numerous ecosystem benefits when grown in the fallow intervals between cash crops. However, given these uncertainties associated with climate change, it is imperative to investigate how CCs will perform under future climate conditions and identify adaptation strategies that enhance CC benefits and minimize tradeoffs. One approach to provide long-term insights of how climate change impacts CC performance and evaluates the effectiveness of adaptation strategies is the utilization of simulation tools such as cropping system models In this study, we conducted long-term simulations using DSSAT to assess the performance of cereal rye cover crop in terms of subsequent corn yield, cover crop biomass, soil hydrology, N leached, and SOC under historical (1991-2020) and future climate conditions (2041-2070) in eastern Nebraska. Our simulation results showed that CC had no significant impact on corn yield under HIST and RCP scenarios for rainfed and irrigated treatments. The change in climate has created a more favorable condition for CC growth and resulted increase in CC biomass compared to historical average. CC managed to reduced N leached through subsurface flow during CC growing season under RCP scenarios compared to an average reduction of 60% (7 kg ha-1) during HIST period. In terms of soil moisture, CC resulted in 6% (27 mm) reduction in total water in soil profile and 22% (27mm) reduction in PAW compared to NCC during HIST period. These reductions further increased to 12% (55 mm) and 13% (60 mm) for total water in soil pro- file and 38% (56mm), and 46% (60mm) for PAW under RCP4.5 and RCP8.5 scenarios, respectively. However, we found that the 10-day period between cover crop termination and corn planting was able to slightly recover soil moisture. In addition, moisture recovery under CC treatment was higher than NCC owing to soil property improvements from CC. Cover crop also managed to reduce cumulative seasonal surface runoff and soil evaporation during CC and corn growing seasons under both HIST and RCP scenarios. Without CC, loss of SOC due to increased rate of soil organic matter decomposition resulted in reduction in rate of SOC buildup in the future despite higher amount of corn biomass. Such information can give insights on likely consequences of climate change and inform crop\management improvement programs, risk management and strategic planning within farm-scale operations.

Technical Abstract: Fall-planted cover crop (CC) within a continuous corn (Zea mays L.) system offers potential agroecosystem benefits including mitigating the impacts of increased temperature and variability in precipitation patterns. A long-term simulation using the Decision Support System for Agrotechnology Transfer (DSSAT) model was made to assess the effects of cereal rye (Secale cereale L.) on no-till continuous corn yield and soil properties under historical (1991-2020) and projected climate (2041-2070) in eastern Nebraska, US. Local weather data during the historical period was used, while climate change projections were based on the Canadian Earth System Model 2 (CanESM2) dynamically downscaled using the Canadian Centre for Climate Modelling and Analysis Regional Climate Model 4 (CanRCM4) under two Representative Concentration Pathways (RCP) namely, RCP4.5 and RCP8.5. Simulations results indicated that CC impacts on corn yield were non-significant under historical and climate change conditions. Climate change created more favorable conditions for CC growth, resulting in an increase in biomass. CC reduced N leaching under climate change scenarios compared to an average reduction of 60% (7 kg ha-1) during the historical period. CC resulted in 6% (27 mm) reduction in total water in soil profile (140 cm) (SW) and 22% (27mm) reduction in plant available water (PAW) compared to no cover crop (NCC) during historical period. CC also reduced cumulative seasonal surface runoff/soil evaporation and increased rate of SOC buildup. This research provides valuable information on the potential impact of climate change on performance of cereal rye CC in continuous corn production and enhance CC adoption.