Ecological and Economic Evaluation of Conventional and New Weed Control Techniques in Row Crops

The Farm to Fork strategy of the European Union aims to reduce pesticide use. In weed control, chemical measures are to be replaced mainly by mechanical ones. However, a comprehensive evaluation of mechanical methods with respect to ecological and economic parameters is not yet available. The aim of the study was to quantify relevant ecological and economic parameters of mechanical, mechanical-chemical and chemical weed control in sugar beet as a model crop. An overall consideration of the multidimensional risks for different conventional and new methods revealed that currently no method can be appraised as fully environmentally friendly. Toxicological risk assessment using the model SYNOPS-GIS indicated that broadcast spraying of conventional herbicides is associated with low toxicological risks in most soil-climate-regions and years. Broadcast spraying with herbicides such as CONVISO ONE, while beneficial for energy use, climatic effects, and toxicity to soil organisms, has the highest acute aquatic toxicity. Conventional mechanical methods, while toxicologically safe and, according to field trials, without negative effects on soil biota, soil erosion, or sugar yield, are associated with 100–150% higher greenhouse gas emissions compared to conventional herbicide application. Overall, hoeing with a solar powered robot combined with herbicide spot spraying has the greatest advantages. This technique requires relatively low resource and energy consumption, produces about 5% lower greenhouse gas emissions and has by 87% lower toxicological risk than conventional herbicide spraying. Among pure mechanical techniques, the combination of a solar-driven hoe robot with hand-hoeing appears to be most economic and environmentally sustainable.