US maize: potential additional soil carbon sequestration (1998 to 2018).

	Annual increase in carbon sequestered based on 1997 average (kg carbon/ha)	Crop area (million ha)	Additional carbon sequestered (million kg)	Additional carbon dioxide sequestered (million kg)
1997	0.0	32.2	0.00	0.00
1998	−5.7	32.4	−183.41	−673.13
2000	−13.1	32.2	−422.85	−1,551.87
2010	64.8	32.8	2,123.58	7,793.55
2015	66.3	32.7	2,166.55	7,951.23
2018	44.1	33.1	1,460.15	5,358.74
Total			19,973.08	73,301.20

Assumption: carbon sequestration remains at the 1997 level of 122.5 kg carbon/ha/year