Table 1 Soil organic carbon (SOC) for all available cropland soils globally (i.e. those not excluded from the analysis as high SOC or sandy soils), showing both the global totals and the global averages per hectare, at current status (T0), and after 20 years for both the medium and high sequestration scenarios, and their annual increment.

From: Global Sequestration Potential of Increased Organic Carbon in Cropland Soils

Cropland Soils (30 cm depth) Soil Organic Carbon Average Soil Organic Carbon per Hectare Cropland Area
Current After 20 Years Annual Increase Current After 20 Years Annual Increase
Scenario T 0 Medium High Medium High T 0 Medium High Medium High
  PgC PgC/yr tC/ha tC/ha/yr km 2
Available Soils 131.81 149.84 168.87 0.90 1.85 82 93 105 0.56 1.15 15,935,304
High SOC Soils 8.34      252      331,227
Sandy Soils 0.14      34      40,999
Total 140.28           16,307,531