Soil is a large repository of carbon. Effective management of land can help increase the influx of carbon while minimizing the loss of carbon from soils. Examples of effective soil management practices include no-till and regenerative agriculture, regenerative grazing, using organic supplements such as manure, planting cover crops, and maintenance of wetlands. Effective land and soil management practices can result in carbon sequestration of 2-5 GtCO2/yr for costs ranging from $0 to $100/tCO2 (Minx et al, 2018). Many options are mature practices and relatively inexpensive, requiring limited technological support. Long term potential of carbon storage from these practices relies, however, on continued management that decreases soil disturbance. For example, tilling grasslands for conventional agriculture would quickly release much of the stored carbon back into the air (Silveira et al, 2018).
Soil carbon sequestration can be intensified through the use of biochar – organic matter burned with limited oxygen through a process known as pyrolysis. Biochar increases agricultural productivity through reducing nutrient input and increasing water retention capability. Widespread application of biochar is estimated to have an annual sequestration potential of 0.5 to 2 Gt CO2 with an average cost ranging from $30 to $120/t CO2 (Minx et al, 2018). Biochar is being researched and piloted widely to help identify further benefits and to lower costs through successful use cases.