Assessment of economic indicators, energy inputs and greenhouse gas emissions applying different weed control technologies for field bean (Vicia faba L.) growing: a case study

A number of methods have been developed and are widely applied to evaluate the production of agricultural crops. These methods generally allow the assessment of technology only from an economic point of view, calculating costs of EUR·ha-1 or EUR·t. To implement the EU green course, there is a need to minimize pesticide use, therefore it is important to evaluate the environmental impact of different methods of pest control. One of the best-known alternatives to herbicides is mechanical weed control. Harrowing and inter-row cultivation were tested during two years in the project. The efficacy of mechanical weed control was good and there was no yield loss when mechanical weed control was combined with a catch crop in field beans, compared to the usual weed control practice where herbicides are used to control weeds in spring. However, there is a concern about additional CO2 emissions created by the mechanical weed control process. It is necessary to evaluate these additional emissions in the context of total CO2 emissions created during the crop production cycle. In this study we take into account (1) the CO2 emissions during the weed control process (2) and the CO2 emissions created during the production, transport, storage and use of machinery, application of fertilisers and plant protection chemicals, burned fuel, and the sowing process. The study evaluated three technologies of weed control in field bean, T1, T2 and T3, with different soil tillage and weed control methods. The most significant difference was between the T2 and T3 technologies. In T2, mechanical weed control, harrowing and interrow cultivation, were used, while in T3 herbicides were used. The amount of fertiliser and most technological operations were the same for all technologies. The results show that for the technology T3 the equated costs are approximately by 9%-11% EUR·ha-1 lower than for technologies T1, T2 with mechanical weed control. The energy investment gap between technologies is small, 5%, while the CO2 equivalent for emission in technology T3 is by 14% lower than in T2 and by 11% lower than in T2. Consequently, the most economically favourable technology is T3 that uses herbicides for weed control. This technology is also the most widely used on the farms. From the point of view of CO2 emissions, fuel, sowing and engineering factors play a major role in the calculation of energy investment and CO2 equivalent emissions, while the herbicide use and fertiliser factors are less important, however, the environmental impact of pesticides is often not taken into account.