Development of a New Unbiased Impact Index on Water for Pesticides Use – A Case Study in Belgium for Herbicides Application on Sugar Beet Crop

Abstract

Reduction of pesticides use is one of the main objectives of the Farm to Fork Strategy developed in the framework of the European Green Deal, aiming to make food systems fair, healthy and environmentally-friendly [4]. The operational target is a 50% reduction in use and risk of chemical pesticides by 2030. The Walloon Region in Belgium is committed to a strong prevention policy to reduce the impact of pesticide residues on human health and the environment, with a particular focus on water resources. This target will be measured based on i) the quantities of active substances by using an unbiased index and ii) the hazard properties of plant protection products (PPP) gathered in a negative list for the water resource. In order to be able to monitor PPP applications at farm level, several indicators have been used, such as the French widespread indicator “TFI” (Treatment Frequency Index). Nevertheless, it was demonstrated that this index implies a systematic bias in the evaluation of active substances used. Therefore, to quantify the pesticides used by farmers, a derived unbiased index called “ISAC” based on Active Substances per Crop has been developed and is now applied to compare several weeds control strategies. A focus on water resources preservation can be realized by selecting problematic active substances (such as chloridazon, metamitron, dimethenamid-P, ethofumesate, lenacile, …) into the ISAC, therefore obtaining an index of pressure on water resources (ISAC’eau). Theses indexes have been applied on Walloon farming practices related to weeds control through herbicides use on sugar beet crop. In conclusion, the use of the Unbiased Impact Index allows relevant comparisons between different strategies that can in fine help to propose alternatives for reducing herbicides use in sugar beet and their impact on the water resources. Obviously, it is necessary to investigate how to manage weeds with less or no herbicides in arable farming while maintaining the productivity, which implies considering agronomic performance such as yield, and crop net profit.