Sol Phy-Ly

Farmers are required to maintain vegetation cover for soil protection purposes. However, to destroy these intercrops and other regrowths, or in the case of no-till plots, it is common to use the chemical route, which often results in the use of glyphosate. The main objective of this project is to compare the impact of glyphosate with other alternatives for total weed control, by chemical and/or mechanical means, assessing their effectiveness as well as retention and leaching of these alternative molecules in soils through analysis of soil and water collected with lysimeters. The second objective is to follow the fate of molecules applied to these experimental plots in order to improve protection of the groundwater resource and the quality of information available for modelling.

Background

For groundwater, current observations reflect practices (active materials, doses, application periods) dating back many years or even decades. The Walloon agricultural fabric as well as water managers need a tool enabling them to assess in the short term the environmental impact of current practices of PPP use. This project will shed light on: - PPP flows at the base of lysimeters (2 metres deep), where the process of biodegradation or 'consumption' by the roots of crops in place is no longer operating;
- the impact of differentiated management of crop residues on the fate of PPPs (lower sensitivity to erosion, increased usable water supply, increased potential for biodegradation of PPPs, etc.)

- potential sustainable alternatives to glyphosate.

Objectives

This research project aims to contribute to:

- assessment of phytopharmaceutical product (PPP) flows by leaching in the open field in sites equipped with lysimeters;

- developing laboratory methods for determining content of active materials (including metabolites);
- assessing the impact of cropping practices (management of crop residues) on the degradation of active materials by the soil and their flow to groundwater;

- proposals for recommendations including the environmental assessment of glyphosate, and

- proposals of alternatives.

Results obtained

Development of several multi-residue analysis methods in the water and soil:

- 39 molecules are being monitored in the soil

- 61 molecules are being monitored in the water

A method for analysis of glyphosate in the water and soil has been developed and validated.

Contribution

Unit 10 of the CRA-W is contributing to this project by bringing its expertise in analysis of phytosanitary products in various environmental matrices. After choosing the molecules to be analysed, the appropriate analytical methods will be developed. Our Unit will then analyse the samples collected from the different sites being monitored.

The results obtained in this way will then be interpreted and disseminated in collaboration with the other partners involved.