Selenium is also taken up by plants from the soil, and while it is not essential for plant growth, it is a vital trace element for the health of humans and livestock, especially for their immune systems. A high content of plant-available selenium in the soil is therefore of great interest for the production of healthy, selenium-rich food. Between half a billion and a billion people have been estimated to have inadequate dietary intakes of selenium today.
A team of researchers from Eawag, ETH Zurich and the US, led by Lenny Winkel and her former doctoral student Ari Feinberg, has now studied the global deposition of sulphur and selenium in a combined modelling approach. They published their findings in today's article Reductions in the deposition of sulphur and selenium to agricultural soils pose risk of future nutrient deficiencies in the Nature Journal "Communications Earth & Environment". The research team used a global aerosol chemistry-climate model to map deposition worldwide in recent years (2005 - 2009) and predict future changes (2095 - 2099) under two socio-economic scenarios.
Decline in sulphur and selenium depositions threatens food production
"Our model calculations show a substantially decreased deposition to agricultural soils," says Feinberg, the study's lead author and currently a postdoctoral fellow at MIT in the US. "Inputs of sulphur could decline by 70 to 90 percent by the end of the 21st century, and those of selenium by 55 to 80 percent." Especially for agricultural land, which is stripped of large amounts of sulphur and selenium through intensive crop harvest, the sufficient supply of nutrients will become a challenge.
In their article, the researchers therefore call for further monitoring of changing nutrient supply to agricultural systems and the further development of sustainable solutions to manage the declines in nutrient inputs. "These actions can help ensure the supply of healthy and nutrient-rich food for the world's population," says Winkel.