27 April 2021

Glyphosate-treated soils say goodbye to invertebrates

An investigation from Mexico finds that use of the controversial pesticide decreases the concentration of macroinvertebrates thus depriving the soil of their ecosystem services

by Matteo Cavallito

 

For years, the use of glyphosate has raised protests as it fueled concern over its impact on human health. Its extremely negative effects for soil ecosystem, however, are less recognized. In order to highlight them, recent studies have been conducted in the Yucatán Peninsula, in southeastern Mexico, and their findings were presented recently during the FAO Global Symposium on Soil Biodiversity. “Glyphosate and its main metabolite, AMPA, can be found in soil even years after applications,” says Esperanza Huerta Lwanga, a researcher at the University of Wageningen, in Netherlands. The damage, the studies suggest, is clear.

Glyphosate and GMOs spread together

The spread of glyphosate in Mexico is closely linked to that of GMOs. In fact, the introduction of genetically modified plants, capable of tolerating the herbicide, says the researcher, has encouraged its use. Not surprisingly, many scientists have been investigating the consequences of this trend for at least a decade. This latest survey in particular shows how the herbicide’s use has a negative impact on the survival of macroinvertebrates, which are essential for soil health. These creatures, indeed, play a key role in the supply of ecosystem services, they take part in the interactions between physical, chemical and biological processes and they are an indicator of soil health.

More herbicide less invertebrates

For their survey, carried out on the vegetation surroundings of the municipality of Hopelchén in the State of Campeche, in the northern area of the Yucatán Peninsula, researchers selected soil samples in three different areas: the land cultivated with soybeans where glyphosate had been used, the corn planted areawhere the herbicide had not been applied, and a non-cultivated land. The study found a negative correlation between the presence of glyphosate and the density of several categories of macroinvertebrates. In other words, where glyphosate was more present, the concentration of macroinvertebrates was lower. In soybean-cultivated soils , in particular, gastropods, such as snails, slugs and others, had completely disappeared. Thus depriving the soil ecosystem of their functions.

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Far-reaching damages

The Yucatán area “is highly vulnerable to pollution” Universidad Autónoma reserachers Angel Gabriel Polanco-Rodriguez and Jesús Alfredo Araujo explained in a 2018 survey. The reasons can be found in its soils and karstic aquifer, “where contaminant filtration processes are facilitated.” Wind also plays an important role as the Hopelchen study has confirmed. Researchers, Huerta Lwanga says, have found significant evidence of glyphosate even in non-cultivated land. A proof of the large extent of the substance’s overall impact.