Concentrations of copper and zinc continued to increase on intensive grassland sites in Switzerland between 2015 and 2019, due to the application of large quantities of farm fertilizers such as slurry and manure. Certain cultures are particularly affected.
In a report published on Friday, the National Soil Observatory (NABO) indicates that concentrations generally remain well below the indicative values of the soil protection ordinance.
However, he recommends “providing a quantity of farm fertilizer proportional to the actual nutrient needs of the plants cultivated at the plot level, in particular on sites where the density of livestock is high”, in order to avoid that concentrations continue to increase.
Less lead and mercury
Concerning special crop sites, in viticulture in particular, certain sites experience copper concentrations which exceed the indicative values by five to six times. These high concentrations are due to the regular application of copper-based phytosanitary products, used in particular to combat downy mildew, including in organic farming.
Exceedances of the guideline value or increases in concentrations have also been noted for cadmium, another heavy metal present in soils particularly when phosphorus mineral fertilizers are used. Only specific sites contained them, according to NABO.
The federal observatory, on the other hand, welcomes the slight change in concentrations of lead and mercury, whereas in the past, significant atmospheric deposits of these metals were formed and accumulated in the ground. This situation is due to the implementation of stricter air protection regulations during the 1990s.
More than 100 observation sites
Since 1985, NABO has been monitoring the impact of heavy metals, but also phytosanitary products, PFAS and microplastics on Swiss soils. He is also interested in biological measurements of soils.
To do this, it relies on a measurement network of 103 long-term observation sites. According to NABO, these reflect combinations of parameters characteristic of Switzerland, such as land use, soil type, geology or altitude.
Two thirds of the sites are agricultural land and about a third are in forest, and a few sites are in protected areas or urban parks.
ats/jop
Business
Related News :