Soil carbon response to projected climate change in the U.S. western corn belt

Authors: Wienhold, Brian; Jin, Virginia; Schmer, Marty; VARVEL, GARY - Retired ARS Employee

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2017
Publication Date: 7/2/2018
Citation: Wienhold, B.J., Jin, V.L., Schmer, M.R., Varvel, G.E. 2018. Soil carbon response to projected climate change in the U.S. western corn belt. Journal of Environmental Quality. 47:704-709.
DOI: https://doi.org/10.2134/jeq2017.09.0379

Interpretive Summary: In the Western Corn Belt future growing season conditions are projected to be warmer with more variable precipitation. A better understanding of how these conditions will influence crop production and soil quality is needed. A soil carbon model was used to estimate changes over a range of tillage practices (chisel, disk, ridge, and no-tillage) and crop rotations (continuous corn or corn – soybean) assuming either that yields would continue to increase at a rate similar to the last several decades or would decline due to negative temperature effects. Changes in soil carbon were estimated for a 17 year period under weather conditions projected for 2065. With increasing yields soil carbon increased slightly or was maintained with conservation tillage (no tillage or ridge tillage) but declined with conventional tillage (disk or chisel tillage) under both crop rotations. With decreased yields soil carbon decreased under all tillage and crop rotations. These results show that management and crop genetics are important to maintaining productivity and soil quality.

Technical Abstract: The U.S. Western Corn Belt is projected to experience changes in growing conditions due to climate change over the next 50 to 100 years. Projected changes include an increase in growing season length, an increase in the number of high temperature stress days and warm nights, and an increase in precipitation with more heavy rainfall events. The impact these changes will have on soil organic carbon (SOC) need to be estimated and adaptive changes in management developed to sustain soil health and system services. The process-based model CQESTR was used to model changes in SOC stocks in continuous corn (Zea mays L.) and a corn-soybean [Glycine max (L.) Merr.] rotation under disk, chisel, ridge, and no-tillage using projected growing season conditions for the next 50 years. Input for the model was based on management and harvest records from a long-term tillage study (1982 to 2015) in eastern Nebraska and model output was validated using measured changes in SOC from 1999 to 2011 in that study. The validated model was used to estimate changes in SOC over 17 years under climatic conditions projected for 2065 under two scenarios 1.) crop yields increasing at the observed rate from 1971 to 2016 or 2.) crop yields reduced due to negative effects of increasing temperature. Model estimated SOC agreed well with measured SOC (R2 = 0.70, P < 0.0001). Validated model simulated changes in SOC under projected climate change differed among the three soil depths. When summed over the 0 to 30 cm depth there were year by rotation by yield trend (p = 0.014) and year by tillage by yield trend (p < 0.001) interactions. With increasing yield trend SOC increased under no-tillage continuous corn and was unchanged under no-tillage corn-soybean and ridge tillage regardless of cropping system. Under chisel and disk tillage SOC declined regardless of cropping system. With declining yields SOC decreased regardless of tillage practice or cropping system. These results highlight the interaction between management and genetics in maintaining yield trends and soil quality.