Balancing Carbon Benefits and Crop Yield: Study Uncovers Trade-Off in Cover Crop Management

A study led by researchers at the Agro-Ecosystems Sustainability Center (ASC) at the University of Illinois, Urbana-Champaign quantifies soil organic carbon (SOC) from cover crops in corn and soybean rotations in agro-ecosystems in the Midwestern United States.

The study published in The biology of global change, used ecosys, an advanced process-based ecosystem model, to evaluate the effects of winter cover cultivation on SOC accumulation under different environmental and management conditions. By understanding how to achieve and improve the benefits of SOC, farmers and policy makers will be able to enact management practices that support fertile fields that also sequester atmospheric carbon dioxide (CO).2) in the soil.

Cover crops have been found to be effective in increasing soil organic carbon by sequestering atmospheric carbon dioxide2 in the soil and thus has great potential to mitigate climate change. An accessible method for measuring the benefits of SOC would help farmers, government agencies, and industries implement climate-smart cover cultivation practices. However, an accurate and cost-effective method for estimating SOC benefits is still largely unavailable.

To help address this need, ASC researchers are taking an ecosystem modeling approach. Their study revealed that growing cover crops can increase SOC by an average of 0.33 megagrams of carbon per hectare per year (which is equivalent to 0.54 tons of atmospheric carbon dioxide per acre per year) in Illinois, and that SOC benefits can be improved by increasing cover. crop biomass. The ecosys model not only helps quantify SOC benefits from cover crops, but also improves scientific understanding of the environmental factors that control SOC benefits, including soil conditions, weather, and crop varieties.

Connecting with the team’s previous work, the researchers also found that there is a trade-off between the benefits of SOC from cover crops and the yield of cash crops. Specifically, if cover crops have larger growth windows, they grow more biomass and therefore have higher SOC benefits. However, under these conditions, there is an increased risk of lower yields of cash crops due to competition with cover crops for resources and nutrients including water, nitrogen and oxygen in the soil; The work was confirmed by a recent pilot study involving ASC members. The different lines of work collectively emphasize the need to carefully manage cover crops to avoid potential risks.

Comprehensive mechanistic modeling can help solve this trade-off problem by simulating cover crop growth under different conditions. In fields of the American Midwest, management practices such as selecting specific cover crop varieties and regulating their growth window are major control factors for their SOC benefits. Through simulation, the modeling approach can help select optimal management practices that maximize the benefits of SOC without compromising crop yield.

“This provides practical tools and insights for practitioners to improve cover crop management and for policymakers to better design agricultural policies,” said Ziqi Qin, lead author of the publication and graduate student in the Department of Natural Resources and Environmental Sciences (NRES) at U of I.

In addition to the benefits of SOC, researchers have also found that cover crops can benefit the soil environment in other ways. Ecosys simulations indicated that the amount of carbon stored in soil microbes increases when cover crops are present. This result is consistent with previous experimental studies that found an increase in soil fertility when cover crops were used.

“Optimal cover crop management practices differ for each field,” said ASC founding director Kaiyu Guan, associate professor at NRES as well as project lead on the newly published study. “Our work identified the trade-off between cover crops and cash crops, further proving the need to develop management guidance and technical assistance for farmers to make better use of cover crops while also preserving the yield of cash crops.”