Table 2.

Farm machinery weights, diesel use, contract costs, direct and indirect energy and emissions. The weights of the tractors are calculated from Wells (2001), other machinery weights are taken from industry sources. The diesel usage is calculated from Anon (2001). The emissions, both direct and indirect, are calculated from the diesel use and the weights of the machinery. Contract costs are calculated from Anon (2001).

Machines	Weight (kg)	Diesel use (l h−1)	Direct energy (GJ h−1)	Indirect energy (MJ h−1)	Direct emissions (kg CO2 eq h−1)	Indirect emissions (kg CO2 eq h−1)	Contract cost (£ h−1)
Tractor <75 kWa	2473	9.90	0.36	34.06	32.09	1.76	31.39
Tractor 75 < 150 kWa	4756	22.60	0.83	65.51	73.25	3.39	50.38
Tractor 150 < 250 kWa	7799	40.20	1.48	107.41	130.29	5.55	76.12
Tractor > 250 kWa	8378	56.50	2.08	115.41	183.12	5.96	89.36
Plough	1950			14.86		1.01
Subsoiler	5500			42.17		2.86
Power harrow	990			7.59		0.51
Drill	7400			56.73		3.85
Sprayer	1120			8.59		0.58
Trailer	3760			86.48		5.87
Combine harvester	8250	34.85b	1.28b	265.07	112.95	15.32	143.46c
Baler	2000			53.33		4.80	45.63
Swather	2100	18.11	0.67	96.43	58.70	4.98	68.67
Grain dryer	3400			26.07		1.77

^aThe upper limit of the tractor ranges is used when calculating the weight except for the >250 kW tractor where a 269 kW tractor was used as the calculation point.

^bThis is the diesel usage and direct energy where the straw is not chopped by the combine harvester.

^cThis is the contract fee for when the straw is not chopped by the combine harvester. If the straw is chopped then this is increased by the cost of the extra diesel needed to perform straw chopping.