Simulated soil organic carbon changes in Maryland are affected by tillage, climate change, and crop yield

Authors: Cavigelli, Michel; Nash, Patrick; Gollany, Hero; Rasmann, Chris; Polumsky, Robert - Wayne; Le, Anh; Conklin, Anne

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/12/2017
Publication Date: 11/30/2017
Citation: Cavigelli, M.A., Nash, P.R., Gollany, H.T., Rasmann, C., Polumsky, R.W., Le, A.N., Conklin, A.E. 2017. Simulated soil organic carbon changes in Maryland are affected by tillage, climate change, and crop yield. Journal of Environmental Quality. 47(4):588-595. https://doi.org/10.2134/jeq2017.07.0291.
DOI: https://doi.org/10.2134/jeq2017.07.0291

Interpretive Summary: Soil organic matter (SOM), which is about 58% carbon, is the foundation of soil quality and soil function. However, the impact of climate change on SOM in agricultural systems is poorly understood. We used data collected from the long-term Farming Systems Project in Beltsville, Maryland and the CQESTR model to predict the effect of climate change on SOM, measured in units of soil organic carbon (SOC), in conventionally tilled and no-till cropping systems. Since future crop yields are uncertain, we simulated five scenarios with differing yield levels (Farming Systems Project crop yields from 1996-2014, and at 10% or 30% greater or lesser than these yields). Without change in climate or crop yields (baseline conditions) CQESTR predicted small increases in SOC (0.014 and 0.021 Mg ha-1 yr-1 in CT and NT, respectively). Predicted climate change alone resulted in an even smaller SOC increase in no-till systems (0.002 Mg ha-1 yr-1) and a decrease in the conventionally tilled system (0.017 Mg ha-1 yr-1). Crop yield declines of 10% and 30% led to SOC decreases between 2% and 8% compared to 2012 levels. Increasing crop yield by 10% and 30% was sufficient to raise SOC 2% and 7%, respectively, above the climate only scenario under both management practices between 2012 and 2052. Thus, the negative impact of climate change on SOC levels could be mitigated by crop yield increases. These results will be of interest to policymakers and scientific colleagues interested in how agricultural management and climate change will impact agricultural sustainability.

Technical Abstract: The impact of climate change on soil organic carbon (SOC) stocks in no-till (NT) and conventionally-tilled (CT) agricultural systems is poorly understood. The objective of this study was to simulate the impact of projected climate change (air temperature and precipitation) on SOC to 50 cm soil depth for a 37-year period (2015-2052) for grain cropping systems in the southern mid-Atlantic region of the US. We used SOC and other data from the long-term Farming Systems Project, in Beltsville, Maryland and CQESTR, a process based soil C model, to predict the impact of cropping systems and climate on SOC. Since future crop yields are uncertain, we simulated five scenarios with differing yield levels (crop yields from 1996-2014, and at 10% or 30% greater or lesser than these yields). Without change in climate or crop yields (baseline conditions) CQESTR predicted an increase in SOC of 0.014 and 0.021 Mg ha-1 yr-1 in CT and NT, respectively. Predicted climate change alone resulted in an SOC increase of only 0.002 Mg ha-1 yr-1 in NT, and a decrease of 0.017 Mg ha-1 yr-1 in CT. Crop yield declines of 10% and 30% led to SOC decreases between 2% and 8% compared to 2012 levels. Increasing crop yield by 10% and 30% was sufficient to raise SOC 2% and 7%, respectively, above the climate only scenario under both CT and NT between 2012 and 2052. Results indicate that under these simulated conditions the negative impact of climate change on SOC levels could be mitigated by crop yield increases.