From the Field
The Dual Benefit of Cover Cropping: Soil Carbon and Increased Crop Yields
Researchers from the Berkeley Agroecology Lab show that, on average, cover cropping leads to climate benefits without sacrificing farm level productivity.
Cover crops play an essential role in agroecosystems, from improving water quality to harboring biodiversity. In recent years, climate scientists have increasingly spotlighted the practice of cover cropping for its potential to sequester carbon and thus serve as a tool for climate mitigation.
The question is, does cover cropping sacrifice farm productivity for the sake of carbon sequestration? The answer, according to a new study from researchers associated with the Berkeley Agroecology Lab: not usually.
Published this week in Nature Sustainability, the study uses a global meta-analysis linking experiments of cover cropping’s influence on soil organic carbon and its influence on yields into a paired observation dataset. Of 434 paired observations, nearly two-thirds showed an increase on both carbon and yield, suggesting that, on average, cover cropping “had a strong positive effect” on both carbon sequestration and on-farm productivity.
The researchers also aimed to understand how that increased soil carbon played a direct role in increased yields, apart from other cover cropping effects not measured like nutrient scavenging. “We wanted to know, are there specific yield benefits from the organic carbon that can’t be achieved by adding the same amount of mineral fertilizer, for example,” says Isaac Vendig, the study’s first author. Vendig started this research as an undergraduate research assistant of the Berkeley Agroecology Lab and continued working with the lab after graduating in 2019.
According to the study, soil organic carbon from cover cropping had a direct influence on yields in soils that initially had relatively low carbon, whether naturally or because the soil carbon had been depleted.
Even apart from these direct effects of soil carbon on yield, legume cover crops showed the highest potential yield increase (up to 24 percent) and soil organic carbon increase (up to 1.5 grams of carbon per kilogram of soil). “With a legume cover crop in a continuous monocrop like corn, for example, you could match some significant soil carbon increases with pretty substantial yield increases,” says Vendig.
At the farm level, this research could offer insight into the contexts in which the benefits to carbon and yields from cover cropping overlap. For the most part, farmers base management decisions not on carbon potential but on productivity. However, the co-benefits of cover cropping could present a “win-win situation” for many growers, says Timothy Bowles, Assistant Professor of Agroecology at UC Berkeley and Co-Associate Faculty Director of the Berkeley Food Institute.
“From a policy standpoint, if we provide incentives for practices like cover cropping, where might we see benefits for both climate mitigation and yields?” says Bowles, “Incentivizing cover crops on some of these low-carbon soils might be the best bang for the buck.”
Coauthors of this study include Isaac Vendig; Aidee Guzman, postdoctoral researcher at UC Irvine and graduate of the Department of Environmental Science, Policy, and Management (ESPM) at UC Berkeley; Gisel De La Cerda, undergraduate research assistant at the Berkeley Agroecology Lab; Kenzo Esquivel, ESPM PhD candidate; Allegra C. Mayer, postdoctoral researcher at the Lawrence Livermore National Lab and ESPM graduate; Lauren Ponisio, Assistant Professor of Biology at the University of Oregon and ESPM graduate; and Timothy M. Bowles. This research was made possible by funding from the Organic Center.