why some farmers have difficulty doing without it – L’Express

If the threats are therefore not entirely clear, suspicions are growing. “It is normal that science cannot answer all the questions, on the one hand because the toxicity of the product is not acute [NDLR : les personnes exposées ne meurent pas le lendemain] and that it is difficult to measure the doses to which we are subjected over the long term, on the other hand because the functioning of living things is extremely complex”, underlines Christian Huyghe, agricultural scientific director of the National Research Institute for agriculture, food and the environment (INRAE). Although the precautionary principle could therefore be applied, it comes up against economic considerations: the low cost of this herbicide and its high effectiveness allow significant productivity gains. The lack of certainty thus pushed the European Food Safety Authority to judge, in a report published on July 6, that there was no “area of ​​critical concern [concernant] the risks of glyphosate on humans, animals and the environment.

“Authorizing its use for ten years without legislating a reduction in approved doses would be a very bad signal,” believes Christian Huyghe, however. Numerous studies, including those of Inrae, show that there are multiple current applications of glyphosate where alternative practices have no major impact on the economic performance of farms. “And, when it is problematic, it is possible to invest in research… which will be all the more motivated if a sharp reduction in the use of glyphosate is imposed,” continues the researcher.

Glyphosate is a systemic herbicide (absorbed by the leaves and which circulates throughout the plant) which kills all plants, except resistant GMO varieties, not cultivated in France. We therefore apply glyphosate to destroy all cover plants before sowing in field crops or between the rows and at the base in orchards and vineyards. Other commonly used techniques include the mechanical weeding method. It consists of plowing the land, scratching the soil or even “scalping” the shallow roots of weeds – weeds – which have grown in the field between two harvests. While these techniques are effective, they are not without their flaws. They all require increased work time – and therefore cost – and are not feasible if the soil is too wet or too dry. In addition, poorly carried out plowing can damage the health of the soil.

It is otherwise possible to sow, between two harvests of a crop, what specialists call “plant covers”, made up of various species, such as radish, brown mustard, phacelia or vetch. Preventing the growth of weeds, they can be easily destroyed mechanically, using rollers placed in front of the tractor. “This allows us to go a little faster than the scalping, but not as much as with glyphosate”, underlines Christian Huyghe. In addition, this method requires technical skills allowing the cover crops to be planted uniformly and to identify the best plant depending on the farm.

Farmers and scientists are also looking into the use of so-called “frost-resistant” species, such as mustard, which are very sensitive to frost and which can be destroyed naturally provided that the winter is sufficiently harsh. The permanent cover method can also be interesting. It consists, for example, of planting wheat in a permanent cover of alfalfa. As the land is permanently occupied, weeds can no longer take root. “That’s the theory, in practice, it requires significant technical skills”, notes Christian Huyghe, who also mentions the interest of the technique of relay cultivation to extend the duration of land occupation while throughout the year. “The idea is to sow the crop of year N + 1 before harvesting the crop of year N, so as to ensure permanent soil cover and have more than one crop per year,” he explains. -he.

The farmer can, for example, sow winter wheat in October, destroy one row out of three in April to sow soybeans, then harvest the wheat, and finally the soybeans. “We must then install specific plates on the combine harvesters which allow only wheat to be harvested,” continues the researcher. Cultivating two species on the same plot also makes it possible to make up for the loss of profitability linked to the removal of a third of the wheat rows. Trials carried out by INRAE ​​with farmers and in other countries even show an average yield 87% higher than the average for monocultures when the species is chosen carefully. Unfortunately, the practice lacks popularity, in particular because it breaks with mentalities and current machines and seeders are not yet fully adapted. It also requires a significant supply of water due to summer relay cultivation. A significant problem given global warming.

Electric weeding, which involves passing current between the top of the plants and the ground in order to roast them, also shows interesting results. Initial measurements suggest that the impact on wildlife – including earthworms – is not neutral, but remains acceptable. However, this method suffers from an efficiency problem, since it turns out to be slower than the scalping. It could nevertheless be considered in specific configurations, in viticulture or at the edge of fields. Finally, pelargonic acid, a herbicide of biological origin, is sometimes presented as a credible alternative. Except that it costs around 10 times more and is not without environmental consequences. “Glyphosate has fallen into the public domain and costs only 3.50 euros per liter. However, weeding 1 hectare requires only 2 liters of this product,” recalls Christian Huyghe.

If it is thus possible to do without glyphosate, this almost always requires reviewing techniques, or even incurring additional expenses, which is all the more true for farms practicing soil conservation agriculture. This method, which aims for maximum productivity, is particularly used in large rapeseed, wheat and barley farms in the south of the Paris Basin. And if the scalping offers a good alternative, it only allows us to weed 2 hectares per hour, whereas with the large sprayers currently available it is possible to apply glyphosate to 24 hectares in one hour. “Today, it is not easy to practice conservation agriculture without glyphosate at equivalent cost,” says the INRAE ​​specialist.

Glyphosate also remains difficult to replace when crops are invaded by weed flora that are ultra-resistant to other herbicides – blackgrass or ryegrass, for example – or in farms invaded by weeds dangerous to health, such as ragweed or datura. . “We must then question more generally the use of herbicides on these farms, because it is their use which leads to these deviations in flora,” adds Christian Huyghe. We then need an additional herbicide, glyphosate, to control the negative effects of selective herbicides used in crops.”

The lack of economically viable alternatives is also encountered in vineyards on steep slopes, or those with narrow row spacing, such as in Champagne or Burgundy. “In these cases, suitable machines are lacking, even if Burgundy winegrowers have developed functional systems,” specifies the scientist. For large vines, inter-row grassing should be the rule with mechanical weeding at the base of the vines. “According to our analyses, the additional cost for winegrowers is limited,” assures the researcher. “The problem lies in a lack of availability of suitable machines and tractor drivers.”

The case of Luxembourg, where glyphosate was banned for two years before being authorized again last spring, clearly illustrates the current issues. Farmers in this small European country, who have had to learn to do without herbicide, tell AFP that this has often required the acquisition of new machines in order to weed mechanically, as well as increased working time. However, although some people are using glyphosate again, particularly on sloping terrain, the reauthorization has not led to a massive return. Which proves, according to the majority union Centrale paysanne, that herbicide is not so crucial in Luxembourg, where livestock farms dominate. A different situation from France, which has around 12 million hectares of meadows out of 28 million useful agricultural areas.