When vegetation is cleared to make way for biofuel cropping, there may be sig­nificant emissions of non-CO2 carbonaceous greenhouse gases, including CO and hydrocarbons. In practice, these gases may add, in CO2 equivalents, 10-20% to the emission of CO2 only (Reijnders and Huijbregts 2008a). Also, if compared with forested land, arable land with annual biofuel crops becomes a reduced sink for CH4 (Powlson et al. 1997). Long-term cultivation has been shown to reduce CH4 uptake and oxidation by soils by 85% in a temperate setting. This may correspond to a reduction of the soil sink for CH4 in the order of 100-200 kg CO2 equivalent ha-1year-1. And the nature of cultivation also matters, with synthetic NH4 fertil­izer completely inhibiting CH4 oxidation, whereas manure has no inhibitory effect (Powlson et al. 1997). When organic wastes of biofuel production are anaerobically converted in open ponds or in dumps, there may be very large emissions of methane (Reijnders and Huijbregts 2008a).