Carbon plays a crucial role in the formation, structure, and functioning of soil organic matter (SOM), which contributes to the overall health of our soils. Soil organic matter is primarily composed of decomposed plant and animal material, which contains carbon. Plants capture carbon from the atmosphere in the form of carbon dioxide (CO2) and convert it into organic compounds. These compounds enter the soil when plant roots die or when plants are eaten by soil organisms like microbes and insects. The organic matter from these decompositions is rich in carbon and the interaction between carbon and SOM is vital for soil carbon sequestration; the process by which carbon is stored in soils for extended periods. Practices such as no-till farming and cover cropping can help enhance soil carbon storage by increasing the amount of organic material added to the soil. Carbon interacts with soil organic matter by contributing to its formation, decomposition, and stabilization. Through microbial processes, carbon is broken down, recycled, and incorporated into different carbon pools in the soil. Healthy soils with high organic matter content are better able to store carbon.
(left) Sun hemp cover crop; (middle) Sorghum cover crop; (right) Summer cover crop mix: sorghum sudangrass, sun hemp, vetch, cowpea, and balansa clover.
Multispecies cover crops can play a significant role in increasing soil organic carbon (SOC) by providing multiple benefits to soil structure, microbial activity, and organic matter inputs. Multispecies cover crops contribute more diverse root systems to the soil compared to single species cover crops. The diversity of roots in a multispecies cover crop mix results in greater overall root mass, which means more organic matter is deposited into the soil as roots die and decompose. When different species are used in a cover crop mix, they produce a wider variety of organic matter, which has different rates of decomposition and stability. Ultimately, multispecies cover crops help build and maintain soil organic carbon stocks by promoting healthy, biologically active soils with enhanced carbon sequestration capacity. These practices not only improve soil fertility and structure but also contribute to climate change mitigation by increasing the soil’s ability to store carbon.
Read more articles in the Winter 2024 CSWCD Newsletter here.
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