Long-term Study Reveals Best Practices for Building Soil Carbon in Agriculture
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EmailInvestigators at MSU’s Long-term Ecological Research including Sasha Kravchenko and Jennifer Miesel, site find 25-year differences in soil carbon gain among cover cropped, no-till, and perennial cropping systems.
Soil carbon, often called the foundation of soil fertility, plays a crucial role in enhancing plant water availability, supporting beneficial microbes and insects, improving drainage, and promoting nutrient cycling and retention of critical plant nutrients like nitrogen and phosphorus. Moreover, carbon stored in soil is carbon kept out of the atmosphere, helping to mitigate climate change and variability. Farming methods that increase soil carbon are key to both soil health and climate smart farming.
Yet soil carbon storage is a slow process – it can take decades to detect measurable carbon change in many if not most agricultural soils. This is why results from a 25-year study of soil carbon gain reported this month by a team of MSU investigators is so valuable. Working at MSU’s Kellogg Biological Station (KBS), researchers show how different farming practices can build soil carbon – but to different degrees and at very different rates.
Key Findings
Field crops like corn, soybean, and wheat grown with winter cover crops sequestered carbon most rapidly, whereas soil carbon did not change in conventionally grown crops. Likewise, no-till practices, in which seeds are planted into unplowed soil using specialized equipment, also built soil carbon but only half as fast as cover crops. In contrast, perennial crops like alfalfa and unmanaged successional vegetation, which could be used as a bioenergy feedstock or as a conservation planting, sequestered carbon even more effectively than cover crops. In addition to examining soil carbon gains over the study period, researchers found a substantial fraction of pyrogenic or fire-derived carbon in soil, a legacy from historical fires that pre-date modern agriculture.
Dr. Carolina Córdova, lead author of the study and now assistant professor at the University of Nebraska-Lincoln, notes that “We were surprised that cover crops were so effective in building soil carbon, which emphasizes the value of keeping living roots in soil for as much of the year as possible.”
Other authors include Professors Phil Robertson, Alexandra Kravchenko, and Jessica Miesel from the Department of Plant, Soil, and Microbial Sciences at MSU. Robertson, who also leads the KBS Long Term Agroecosystem Research program, emphasizes the importance of such extended studies: “Long-term studies like this are crucial for providing credible evidence that can inform policy, and is possible only because of the commitment of MSU and funding agencies to long-term research, all too rare in the U.S. especially in agriculture.” The study was performed at the KBS Long-term Ecological research site, funded since 1988 by the National Science Foundation and also supported by Michigan AgBioResearch.
Implications for Sustainable Agriculture
The study findings have significant implications for sustainable agriculture for farmers and policymakers seeking to implement climate-smart agricultural practices that enhance soil health and contribute to climate change mitigation. For instance, cover cropping is a powerful tool for building soil carbon even in cropping systems that are plowed. No-till and diverse perennial plantings also emerge as effective ways to build long-term soil carbon stores.
Publication
Córdova, S.C., Kravchenko A. N., Miesel, J., Robertson, G. P., 2024. Soil carbon change in intensive agriculture after 25 years of conservation management. Geoderma, 453, 117133. https://doi.org/10.1016/j.geoderma.2024.117133
