Agriculture is a significant contributor to the emission of greenhouse gases, including carbon dioxide, methane and nitrous oxide. At the same time, carbon dioxide is sequestered in plant biomass, and the lifetime and the decomposition rate of the organic matters will influence the carbon balance between the terrestrial ecosystems and the atmosphere. Due to the pressing need to mitigate the rising concentrations of greenhouse gases and the associated global warming, changes in agricultural practices must be envisaged. After ten years of GM crop cultivation, it is possible to draw conclusions on the effects of GM technology adoption on greenhouse gas emission and CO2 sequestration:

1.GM technology reduces tractor fuel consumption, due to the lower number of pesticide applications and to the shift from conventional tillage to ‘conservation’ tillage cropping. Due to the efficacy of post-emergence weed control as permitted by the RR (Round-up Ready) technology, a significant number of farmers have moved to this ‘conservation’ tillage, which means that traditional, labour-intensive ploughing is substituted by more gentle techniques for preparing the seed bed, saving tractor fuel.

2.

2.GM technology contributes to increase carbon sequestration in the biomass, as conservation tillage results in increased carbon retention in the soil organic matter. This cropping system also reduces the emission of other greenhouse gases, like the nitrous oxide, released in the atmosphere as a side effect of inorganic nitrogen fertilization, which is also reduced by conservation tillage and the associated maintenance of higher organic nitrogen in the soils.

3.

Brooks and Barfoot recently presented a detailed account of  such environmental impacts after ten years of GM crop adoption.(1) Let’s read their conclusion: In 2005, the permanent carbon dioxide savings from reduced fuel use was the equivalent of removing nearly 0.43 million cars from the road for a year and the additional soil carbon sequestration gains were equivalent to removing nearly 3.58 million cars from the roads. In total, GM crop-related carbon dioxide emission savings in 2005 were equal to the removal form the roads of nearly 4.01 million cars, equal to about 17% of all registered cars in the UK.