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.