US maize: permanent reduction in tractor fuel consumption and reduction in carbon dioxide emissions (1998–2018).

	Annual reduction based on 1997 average (liters/ha)	Crop area (million ha)	Total fuel saving (million liters)	Carbon dioxide (million kg)
1997	0.00	32.19	0.00	0.00
1998	−0.55	32.44	−17.83	−47.60
2000	−1.29	32.19	−41.39	−110.51
2010	6.33	32.78	207.64	554.40
2015	6.48	32.68	211.76	565.39
2018	4.34	33.08	143.69	383.65
Total			1,964.21	5,244.44

Assumption: baseline fuel usage is the 1997 level of 42.6 liters/ha