Tracing the fate of 15N-labelled animal manure in the environment

Background • Nitrate leaching threatens both the environment and drinking water quality • Switzerland ca. 380,000 ha with > 25 mg nitrate/L in groundwater (quality criteria for drinking water) [1]; the Gau region (Canton Solothurn) is especially vulnerable • Organic fertilizers(slurry, farmyard manure, etc.) might entail considerably increased leaching risks due to variable nitrogen (N) content and availability • Aim: increase N use efficiency, simultaneously reduce leaching