Land use More heavy metal detected in Swiss grassland

There is a significant increase in copper and zinc concentrations in intensively farmed grassland plots. This can be attributed to the regular application of large quantities of farmyard manure, which contains the micronutrients copper and zinc.

Copper and zinc accumulation in the soil can be assumed, especially when farmyard manure is used for several years and is greater than the amount of nutrients absorbed by the grass. This was announced by the Federal Office for the Environment (FOEN) on Friday. The findings are based on the results of the seventh National Soil Monitoring of Switzerland (Nabo).

In special crops such as viticulture, increases in copper concentrations five to six times higher than the guideline values were recorded. These observations can be explained by the use of plant protection products containing copper, which are used in viticulture to combat downy mildew, among other things, the report continued. At the Nabo vegetable-growing site, the changes observed can be attributed more to the use of farmyard fertilizers.

Natural as well as man-made processes such as climate change can lead to carbon stored in the soil being released into the atmosphere as carbon dioxide. The concentration of organic carbon is lowest on arable land and more than twice as high as on grassland and forest sites.

The changes over time are small, wrote the FOEN. Changes in the concentration of organic carbon are due to changes in the amount of farmyard manure applied.

As part of the Nabo, the state and development of soil health has been measured at 100 monitoring sites since 1985 on the basis of defined soil properties. The seventh survey covers the development over time from 2015 to 2019. The top 20 centimetres of the soil are examined in the monitoring process.

SDA