The Potential of Summer Cover Crops for Building Soil Carbon in Sandy Soils

Research led by Precious Nyabami shows that summer cover crops can help build soil carbon in sandy subtropical vegetable systems, where soil organic matter accumulation is often difficult because of warm, humid conditions and coarse-textured soils.

Why it matters

Sandy soils in subtropical regions often have low organic matter and limited capacity to retain carbon. This makes it challenging for growers to build long-term soil health. The study shows that summer cover crops can still improve soil organic matter and active carbon pools within a few years, even under conditions where carbon accumulation is difficult.

The study compared four summer cover crop monocultures, including two grasses and two legumes, with a four-species mixture over three years. After three years of cover crop management, soil organic matter increased, along with two labile carbon pools: permanganate-oxidizable carbon and mineralizable carbon.

Interestingly, the different cover crop monocultures and the mixture had similar effects on soil carbon pools. This suggests that, in this system, the most important factor may not be which cover crop is planted, but whether the soil is kept covered and plant residues are returned to the soil.

Takeaway:

In sandy subtropical vegetable systems, keeping the soil covered with summer cover crops can help build soil organic matter and improve active carbon pools within a few years.

Reference: Nyabami, P., Weinrich, E., Maltais-Landry, G., & Lin, Y. (2024). Three years of cover crops management increased soil organic matter and labile carbon pools in a subtropical vegetable agroecosystem. Agrosystems, Geosciences & Environment, 7, e20454. https://doi.org/10.1002/agg2.20454