However, the rate of loss of carbon as the cultivation period lengthens declines quickly and soon approaches a steady state, becoming neutral with respect to carbon dioxide emissions. Farming practices with the greatest potential for retention of carbon in the soil include reduction in summer fallow and use of minimum tillage. Indeed, proper management practices have been shown to increase the amount of carbon in the soil, removing carbon dioxide from the atmosphere in the process 3 . The extent to which such management practices can abate the greenhouse effect can only be estimated at present. It is worthy to note that these management practices also contribute to the sustainability of agriculture.
Less information is available on nitrous oxide emissions from prairie soils.
Denitrification losses from prairie soils have arisen under cultivation but the extent to which these have taken place is unknown. In order to understand the role of agriculture with respect to nitrous oxide emissions, it will be necessary to determine the effects of different tillage practices. Nitrous oxide from application of fertilizer can contribute to the total level of emissions. On the other hand, the net impact of agriculture on the accumulation of radiatively active gases in the atmosphere can be expected to be minimal. Most of the accumulation arises from the combustion of fossil fuels.