Location: Soil Management and Sugarbeet ResearchTitle: What long-term research can tell us about agroecosystem C storage potential
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/2020
Publication Date: 11/9/2020
Citation: Stewart, C.E., Jin, V.L., Liebig, M.A., Calderon, F.J., Vigil, M.F. 2020. What long-term research can tell us about agroecosystem C storage potential. Meeting Abstract.
Technical Abstract: Agroecosystem management impacts long-term sustainability of crop production and soil health. Soil organic C is an overall soil health metric and an important greenhouse gas sink for mitigating climate change. Long-term studies are critical in determining the overall impact of conservation management practices. Here, we characterized the impacts of 71 years of cultivation on surface soil carbon (0-12”) at three long-term sites in Akron Colorado, Big Spring Texas, and Moccasin Montana, which span a broad climatic gradient. Sites at Big Spring and Moccasin lost 14-30% SOC and N since 1947. Conversely, SOC increased by 16% at Akron, likely due to the inclusion of conservation management practices such as no-till and continuous cropping. Stable isotope values for SOC shifted to a more C3 signature, reflecting long-term inputs from C3 crops such as cotton, wheat, and other small grains. Interestingly, over seven decades, soil textures changed, which was an unexpected result given that texture is considered a stable inherent soil property. Soil organic carbon was related to changes in percent silt+clay at all sites. A decrease in SOC was correlated with a decrease in silt+clay content at Big Spring. However, the decrease in SOC at Moccasin was correlated with and an increase in silt+clay content. Together, these results suggest changes in physical properties over time, perhaps due to erosion or deposition, will contribute substantially to SOC stock changes. Estimates of soil C storage potential that rely on soil texture will need to account for changes over time. Best-management practices, such as no-tillage and implementation of continuous cropping at these sites will be critical in maintaining soil health.