. 2012 Apr 16;2(2):195–220. doi: 10.3390/ani2020195

Table A4.

Sources of carbon dioxide emissions related directly and indirectly to on-farm fossil fuel use for each crop and pasture.

Gas/Source	Fraction, emission factor, equation	Reference
CO₂ machine operations (kg CO₂ ha⁻¹)	= ∑_Embodied +∑_Fuel+ ∑ _Lubricants	[32,33]
CO₂ Embodied (kg CO₂ ha⁻¹)	=( (MJ hr⁻¹ _{equipment unit}) / (43.99 (MJ L⁻¹)) × (2.639 kg CO₂ L⁻¹) / work rate (ha h⁻¹)	[32,33]
CO₂ Fuel (kg CO₂ ha⁻¹)	=( MJ h⁻¹ _{power unit}) / (43.99 (MJ L⁻¹_diesel)) × (2.639 kg CO₂ L⁻¹) / work rate (ha h⁻¹)
CO₂ Lube (kg CO₂ ha⁻¹)	= (MJ h⁻¹_Lube) / (43.99 (MJ L⁻¹)) × (2.639 kg CO₂ L⁻¹) / work rate (ha h⁻¹)	[32,33]
Work rate (ha h⁻¹) = power unit, implement and width. Fuel use rate (L h⁻¹) = Diesel fuel by power unit, implement and width Lube use rate = oil and grease etc. (MJ h⁻¹) implement and power unit combination) 43.99 MJ L⁻¹ diesel fuel 2.639 kg CO₂ L⁻¹ diesel fuel		[34] [32,33]
CO₂ Cropping inputs (kg CO₂ ha⁻¹)	=∑_seed +∑_fertilizer + ∑ _herbicide
CO₂Seed (kg CO₂ ha⁻¹)	= MJ kg⁻¹ _{seed production} / 43.99 MJ L⁻¹ × 2.639 kg CO₂ L⁻¹ × seeding rate (kg ha⁻¹)	[32,33]
CO₂ Fertilizer (kg CO₂ ha⁻¹)	= MJ kg⁻¹ _nutrient / 43.99 MJ L⁻¹ × 2.639 kg CO₂ L⁻¹ × nutrient rate (kg ha⁻¹)	[32,33]
CO₂ Herbicide (kg CO₂ ha⁻¹)	= MJ kg⁻¹ _herbicide / 43.99 MJ L⁻¹ × 2.639 kg CO₂ L⁻¹ × herbicide rate (kg ha⁻¹)	[32,35]
Seed production MJ kg⁻¹ energy to produce 1 kg seed for purposes of crop seeding Nutrient = 53 MJ kg⁻¹ urea-N; 14 MJ kg⁻¹ P₂O₅; 9 MJ kg⁻¹ K₂O manufacture and transportation Herbicide = 373 MJ kg⁻¹ ai Glyphosate and 104.5 MJ kg⁻¹ ai Dicamba and 2,4-D amine and Mecoprop		[33] [36] [35]