This blog originally appeared on the National Sustainable Agriculture Coalition (NSAC) website, and is re-posted here with permission.
As the climate continues to warm, agriculture has a critical role to play in not just reducing Greenhouse Gas (GHG) emissions, but also in pulling GHG’s out of the atmosphere and storing them in the soil.
Today, the National Sustainable Agriculture Coalition and Breakthrough Strategies and Solutions, LLC, jointly published a paper that explores how soil carbon is sequestered, the state of soil carbon research, and the debate on its potential. It offers a set of recommendations for ongoing research and highlights the many co-benefits of increasing soil carbon.
The paper was written by Daniel Kane, a soil scientist and agroecologist who researches soil carbon cycles, regenerative agriculture, and sustainable food systems.
“Based on global estimates of historic carbon stocks and projections of rising emissions, soil’s usefulness as a carbon sink and drawdown solution appear essential (Lal, 2004, 2008),” Kane explains. “Since over one third of arable land is in agriculture globally (World Bank, 2015a), finding ways to increase soil carbon in agricultural systems will be a major component of using soils as a sink.”
The paper begins by providing an introduction to soil carbon and the process of sequestration. It then explores research findings on soil carbon saturation and the impacts of fertilizers on soil carbon, before providing an analysis of agricultural activities and systems that can sequester carbon. Those activities and systems include conservation tillage and no-till farming, cover crops and resource-conserving crop rotations, managed rotational grazing, and perennial cropping systems.
The paper also briefly explores the co-benefits associated with increasing soil carbon, including maintaining soil structure, improving soil water retention, fostering healthy soil microbial communities, and providing fertility for crops.
In one of the final sections of the paper, Kane addresses the critical issue of land conversion and its impact on GHG emissions and sequestration. As Kane notes, “historic land use conversion of native ecosystems to agriculture is responsible for soil carbon reductions as high as 60-75% (Lal, 2011).”
The paper points to the Conservation Reserve Program, which pays producers to set land aside for 10-to-15 years rather than cropping that land. It also points to the Sodsaver program, which reduces the incentives caused by federal subsidies for tilling formerly uncropped land, such as native prairie. The report notes that these programs have been successful, but that they “can at times be overwhelmed by commodity market upswings or perverse federal production subsidies (Stubbs, 2014).”
The report concludes by recommending a future research agenda to advance our understanding of soil carbon and the systems that facilitate sequestration. The recommended areas of future research include:
- The impacts of increasing root biomass, diversifying rotations, and other non-conventional practices;
- Soil carbon sequestration dynamics, including the interaction of soil carbon with other components of the soil, namely the soil mineral fraction and soil microbial and fungal communities;
- Improving soil carbon modeling and extending predictions so that sustainable systems such as intensive grazing management, inter-cropping, and relay-cropping systems, including those with cover crops sown into standing crops, can be more accurately modeled;
- Improving in-field GHG monitoring capable of capturing temporal and spatial emissions variability;
- Developing inexpensive, field-based tools and measurement protocols that are accessible to producers; and
- Economic research to understand barriers to adoption of conservation systems and how to overcome them.