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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Rangeland Resources & Systems Research » Research » Publications at this Location » Publication #344484
Title: Climate change impacts on yields and soil carbon in dryland agriculture

Author
item ROBERTSON, A - Colorado State University
item ZHANG, Y - Colorad0 State University
item Sherrod, Lucretia
item ROSENZWEIG, S - Colorado State University
item Ma, Liwang
item AHUJA, L - Retired ARS Employee
item SCHIPANSKI, M - Colorado State University

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2017
Publication Date: 12/22/2017
Citation: Robertson, A.D., Zhang, Y., Sherrod, L.A., Rosenzweig, S.T., Ma, L., Ahuja, L.R., Schipanski, M.E. 2017. Climate change impacts on yields and soil carbon in dryland agriculture. Journal of Environmental Quality. doi:10.2134/jeq2017.08.0309.
DOI: https://doi.org/10.2134/jeq2017.08.0309

Interpretive Summary: Soil carbon (C) sequestration under current management practices in dryland agroecosystems needs to be assessed under projected climate change conditions. We examined productivity and soil C dynamics under two IPCC climate change scenarios (RCP 4.5; RCP 8.5), utilizing long-term experimental data and the DayCent model across three sites with an evapotranspiration (ET) gradient in the U.S. High Plains. Each site included a no-till cropping rotation introduced in 1985 with treatments ranging from wheat-fallow to continuous annual cropping and perennial grass. Simulations were extended to 2100 using projected climate data from 16 global circulation models. Simulated yields generally declined for all crops (up to 54% for wheat), with small changes after 2050 under RCP 4.5 but continued decrease to 2100 under RCP 8.5. Of the cropping systems, continuous cropping had the highest average productivity and soil C sequestration rates (69.7 lb C per acre per year from 2015 to 2045 under RCP 4.5), but also the highest uncertainty. Any increase in soil C for crop rotations was realized by 2050, but grassland treatments increased soil C (up to 69 %) through 2100, even under RCP 8.5. Our simulations indicate that reduced frequency of summer fallow can both increase annualized yields and sequester more soil C. As ET is likely to increase in dryland regions, excluding fallow years from dryland agricultural rotations may enhance the resilience of these systems to climate change.

Technical Abstract: Dryland agroecosystems could be a sizable sink for atmospheric carbon (C) due to their spatial extent and level of degradation, providing climate change mitigation. We examined productivity and soil C dynamics under two IPCC climate change scenarios (RCP 4.5; RCP 8.5), utilizing long-term experimental data and the DayCent process-based model for three sites with varying soil conditions along an evapotranspiration (ET) gradient in the U.S. High Plains. Each site included a no-till cropping intensity gradient introduced in 1985 with treatments ranging from wheat-fallow to continuous annual cropping and perennial grass. Simulations were extended to 2100 using data from 16 global circulation models to estimate uncertainty. Simulated yields generally declined for all crops (up to 54% for wheat), with small changes after 2050 under RCP 4.5 and continued losses to 2100 under RCP 8.5. Of the cropped systems, continuous cropping had the highest average productivity and soil C sequestration rates (78.1 kgC ha-1 yr-1 from 2015 to 2045 under RCP 4.5). However, these predictions also had the highest uncertainty for continuously cropped treatments. Any increase in soil C for cropped rotations was realized by 2050, but grassland treatments increased soil C (up to 69 %) through 2100, even under RCP 8.5. Our simulations indicate that reduced frequency of summer fallow can both increase annualized yields and store more soil C. As ET is likely to increase in dryland regions, excluding fallow years from dryland agricultural rotations may represent a means to enhance the resilience of these systems to climate change while also increasing soil C storage and offsetting further warming.