KBS132:Soil carbon sequestration in response to land use change (model results)

Soil carbon sequestration is a significant CO2 mitigation strategy but precise assessments of sequestration require spatially explicit modeling of potential changes in soil organic carbon (SOC) in response to soil, climate, land condition and management interactions. We assessed the sequestration potential of the Eastern Corn Belt (ECB) in the USA (Indiana, Kentucky, Maryland, Michigan, Ohio, Pennsylvania, and West Virginia) in response to the adoption of conservation farming practices and land use change (pasture and forestation) using the SOCRATES model. Input data was provided through an intersection of the STATSGO, National Land Cover Database and a PRISM climate surface. At the end of the 20th century, the 15.3 Mha of cropped soils in the ECB contained 632 Tg C, a reduction of 52% since the introduction of agriculture in the mid-1800’s. Complete adoption of no-tillage practices on prime cropland would potentially recover 147 Tg SOC over 20 years, whereas a continuation of conventional tillage would produce a loss of 35 Tg SOC. Sequestration hotspots (> 500 Gg increase in SOC) under no-tillage cover 2.3 Mha providing 28 Tg C over 20 years. The conversion of marginal (non-prime) agricultural lands to forests would yield an additional 13 Tg C in SOC and 381 Tg C in aboveground biomass. The rehabilitation of minelands to forests would yield an additional 4 Tg C in SOC and 42 Tg C in biomass. Opportunities to sequester C in the ECB via tillage and reforestation are substantial and should be incorporated into regional and national climate change mitigation strategies.