N-Auswaschung unter ökologisch und konventionell bewirtschafteten Praxisflächen in Norddeutschland – Ergebnisse aus dem Projekt COMPASS

Summary

Nitrogen (N) leaching, especially in the form of nitrate (NO3-), still represents a major environmental impact from agriculture. In order to estimate potential N leaching losses under conditions on commercial farms in Northern Germany, N leaching was analyzed by using ceramic suction cups on representative fields on eight organic and conventional farms. On dairy farms, permanent grassland and maize for silage were analyzed as the main fodder crops. On arable farms, one crop with a high risk and one with a low risk of N leaching losses were selected. On permanent grassland, N leaching was pronouncedly lower on organic farms. If grass/clover on organic farms was ploughed, high amounts of N were leached in the following winter, irrespective if grass/clover was ploughed in spring or in late summer. N management on organic farms, especially the management of crop residues, still needs to be improved to meet the N demand of crops and to reduce N losses.