Modeling surface runoff and soil loss response to climate change under GCM ensembles and multiple cropping and tillage systems in Oklahoma

Authors: YUAN, LIFENG - University Of Oklahoma; Zhang, Xunchang; Busteed, Phillip; Flanagan, Dennis; SRIVASTAVA, ANURAG - University Of Idaho

Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2021
Publication Date: 3/7/2022
Citation: Yuan, L., Zhang, X.J., Busteed, P.R., Flanagan, D.C., Srivastava, A. 2022. Modeling surface runoff and soil loss response to climate change under GCM ensembles and multiple cropping and tillage systems in Oklahoma. Soil and Tillage Research. 218. Article 105926. https://doi.org/10.1016/j.still.2021.105296.
DOI: https://doi.org/10.1016/j.still.2021.105296

Interpretive Summary: To develop effective conservation practices to respond to future climatic challenges, the effects of various cropping and tillage systems on surface runoff and soil loss need to be evaluated under extensive geographical conditions. This study used a total of 100 climate scenarios generated from 25 downscaled Global Climate Model projections under two greenhouse gas emissions (RCP4.5 and 8.5), and combined 29 cropping and tillage systems to simulate surface runoff, soil erosion, and crop production response to climate change using the Water Erosion Prediction Project (WEPP) model in central Oklahoma. The results showed that average annual precipitation was projected to significantly decrease by approximately 4-6% (p < 0.05) during 2021-2080 under the two RCPs. Mean annual temperatures were projected to significantly increase (p < 0.01) by 1.74 degree Celsius for RCP4.5 and 1.99 degree Celsius for RCP8.5 during 2021-2050, and 2.65 degree Celsius for RCP4.5 and 3.90 degree Celsius for RCP8.5 during 2051-2080. Annual runoff and soil loss averaged over the two RCPs and all crop types was projected to decrease by approximately 1% and 3%; predicted yields of all crops decreased by about 10.3-18.3% except for cotton during 2021-2080. Simulated annual runoff depth followed the order of Reduced Tillage (RT) > Delayed Tillage (DT) > No Tillage (NT) > Conventional Tillage (CT), and the soil loss followed the order of RT > CT > DT > NT under future climate scenarios. WEPP-simulated runoff with different crops followed the order of canola > wheat > sorghum > soybean > cotton > crop-alfalfa > wheat-soybean rotation, and soil loss the order of soybean > cotton > canola > sorghum > wheat > crop-alfalfa. No-till and the crop-alfalfa rotation would be the most effective soil conservation method on farmlands. This work provides useful information to soil and water conservationists to develop new conservation strategy to mitigate the adverse impact of climate change on agricultural production and sustainability.

Technical Abstract: To develop effective conservation practices to respond to future climatic challenges, the effects of various cropping and tillage systems on surface runoff and soil loss need to be evaluated under extensive geographical conditions. However, a few combinations of General Circulation Models (GCMs) and cropping and tillage systems might lead to inaccurate assessment of runoff and soil loss under climate change due to the lack of multiple GCM ensembles. This study used a total of 100 climate scenarios generated from 25 downscaled GCM projections under two Representative Concentration Pathways (RCP4.5 and 8.5) during 2021-2050 and 2051-2080, and combined 29 cropping and tillage systems to simulate surface runoff, soil erosion, and crop production response to climate change using the Water Erosion Prediction Project (WEPP) model. The results showed that average annual precipitation in Oklahoma was projected to significantly decrease by approximately 4-6% (p < 0.05) during the two periods under the two RCPs. Mean annual temperatures were projected to significantly increase (p < 0.01) by 1.74 degree Celsius for RCP4.5 and 1.99 degree Celsius for RCP8.5 during 2021-2050, and 2.65 degree Celsius for RCP4.5 and 3.90 degree Celsius for RCP8.5 during 2051-2080. Annual runoff and soil loss averaged over the two RCPs and all crop types was projected to decrease by approximately 1% and 3%; predicted yields of all crops decreased by about 10.3-18.3% except for cotton during 2021-2080. Simulated annual runoff depth and soil loss separately followed the order of Reduced Tillage (RT) > Delayed Tillage (DT) > No Tillage (NT) > Conventional Tillage (CT) and RT > CT > DT > NT under future climate scenarios. WEPP-simulated runoff and soil loss with different crops followed the order of canola > wheat > sorghum > soybean > cotton > crop-alfalfa > wheat-soybean rotation, and soybean > cotton > canola > sorghum > wheat > crop-alfalfa, respectively. No-till and the crop-alfalfa rotation would be the most effective soil conservation method on farmlands, and recommend for use across large area if economically feasible.