Plants and animals need large quantities of the nutrients nitrogen and phosphorus for their growth. Often, however, sufficient quantities of nutrients are lacking in the soil and in fodder produced on the farm. For this reason, farmers fertilise plants and supplement the feed distributed to their livestock with purchased fodder. As is the case with us humans, the animals are unable to utilise a substantial proportion of the nutrients in the feed, and eliminate these in their faeces and urine. A percentage of the nutrients in slurry, farmyard manure, purchased fertilisers and soil, however, is lost in animal houses, pasture and field, and ends up in the air or water, where they become environmental pollutants. ART is therefore using so-called nutrient balances to calculate potential nitrogen and phosphorus losses for Swiss agriculture. The results show that air and water pollution have been declining over the past few years owing to the ecological measures taken by farmers.