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Less Fallow Sustains Soil Carbon Longer with Climate Change

 

Semi-arid regions constitute 20% of Earth’s land surface and support growing populations that are under increasing pressure from land degradation and changing climates. Low soil carbon levels are common in dryland agriculture of the US High Plains due in part to the traditional practice of unvegetated fallows for 14 of every 24 months in rotation with winter wheat to conserve rainwater and stabilize yields. Recent evidence shows that more intensive cropping can both increase annualized yields and increase soil carbon stocks, but how this management fares under climate change is still unclear.

In a paper recently published in the Journal of Environmental Quality, researchers examine the effects of cropping intensity and climate change on soil carbon and yields across the US High Plains, running DayCent simulations from current day through 2100.

Both measured and modeled results indicated that increased cropping intensity can create a win-win scenario for yields and soils. Although climate change is predicted to reduce yields of all crops simulated (up to 50 % by 2100), continuously cropped rotations had higher yield averages under climate change as well as higher soil carbon sequestration rates (up to 78 kg C ha-1 yr-1 in topsoil, 0-20 cm) up to 2045 and the lowest soil carbon losses after 2050.

Given the likely increase in drought frequency over the coming century, agricultural management systems need to be both resilient and flexible given unpredictable conditions. Integrated field and modeling approaches provide the scientific basis for producers to implement adaptive management practices, ultimately helping to provide win-win outcomes that maintain yields and mitigate the carbon dioxide emissions associated with agriculture.

 

Read the full open access article in JEQ.