An environmental comparison of techniques to reduce pollutants emissions related to agricultural tractors

Agriculture is responsible for considerable environmental impact. Much of the impact is related to mechanisation and, in particular, to tractor emissions. Agricultural tractor manufacturers have been forced to adhere to increasingly stringent limits on engine exhaust gas emissions in recent decades. Among the most recent technical solutions to reduce pollutant emissions are included Exhaust Gas Recirculation (EGR) and Selective Catalytic Reduction (SCR), both of which involve critical issues, such as the increase in specific fuel consumption (EGR) or the consumption of a urea solution (SCR). Only a few studies have focused on the environmental consequences related to the application of these solutions to operational agricultural tractors to date. This study employed the life cycle assessment approach to evaluate the environmental impact of ploughing conducted with two very similar tractors, the first being equipped with EGR and the second with SCR. More in details, considering a full set of environmental indicators, the environmental impact of ploughing carried out with the tractor equipped with the EGR is compared with the ones carried out with the tractor equipped with SRC. The results show that the SCR-equipped tractor reduced all the impact categories affected by NOX and particulate matter emissions (from −59% for acidification to −73% for marine eutrophication). However, the influence on Climate Change was much lower (−3%), mainly for the increase of Freshwater Eutrophication (due to the consumption of urea solution in the SCR, as well as to the consumption of tractor, and metal depletion for the higher mass of the tractor).