Assessment of the greenhouse gas emissions and energy inputs applying different weed control methods for wheat growing
¹Latvia University of Life Sciences and Technologies, Institute of Plant Protection Research ‘Agrihorts’, 2 Paula Lejiņa street, LV–3001 Jelgava, Latvia
² Latvia University of Life Sciences and Technologies, Ulbroka Research Center, 1 Instituta street, LV–2130 Ulbroka, Latvia
Economic indicators are often used to evaluate and select technologies, determining the production costs of the product. However, according to the EU’s green course, the ecological assessment of technologies is increasingly important. The purpose of the article is to comparatively evaluate two winter wheat weed control methods, which are widely used in Latvia, according to two ecological indicators – the amount of the GHG emissions and the energy consumption, to find out whether these indicators can serve as a criterion for the selection of technologies. These two methods are HA (harrowing), in which weeds are controlled by harrowing and herbicides, HE (herbicides), in which weeds are controlled only by herbicides. The methodology for calculating the mentioned indicators was developed by analyzing several studies by other authors. The total GHG emissions generated are calculated as the sum of five components: emissions, generated for the manufacture and delivery of the machinery used; emissions, generated by the fuel, consumed for implementation of the technology; emissions, generated for the production, delivery and installation of fertilizers; emissions, generated for the production, delivery and installation of pesticides, seed production, delivery and installation emissions. Analogously, the total energy consumption is calculated by summing the components The technologies were implemented on a specific farm, with the machinery of this farm, labor, fertilizers and the plant protection products. It has been established that the technologies differ by the calculated ecological indicators within the range of 1.2–2.6%; moreover, these indicators are lower for the technology with the herbicide spraying, and the technology is simpler to implement. Therefore, it is also more widely used. Since the coefficients for the calculation of the ecological indicators can be applied by the methodology of this article, the characteristics of the technique and the doses of fertilizers and the plant protection agents, used on the farms, are known, the ecological indicators can be used as an additional criterion for the selection of technologies on the farms. The ratio of the energy value and energy consumption of the produced product (the output and the input ratio) was also determined, this indicator for technologies HA and HE being, respectively, 8.30 and 8.41. In comparison with the research by the authors in other countries, from the point of view of the amount of the generated CO2-eq emissions and rational consumption of energy, the analysed winter wheat production technologies are evaluated as moderately efficient, but from the point of view of the energy value of the product produced and the ratio of the energy consumption (the output and the input ratio) – as efficient.