Welchen Einfluss hat die Dauer der biologischen Bewirtschaftung auf den Ertrag und die Biodiversität im Maisanbau? Ergebnisse einer Praxisstudie

Organic farming is popular, and an increasing number of conventional farmers consider to convert to organic farming. For those converting, and for policy makers, it is important to know whether plant yield changes with the duration of organic management and whether other aspects of organic management (e. g. weed abundance or enhanced weed diversity) increase over time. In order to test this, we compared maize yield on 34 farms: 9 conventional farms, 9 farms which recently converted to organic farming as well as 16 farms which were managed organically for 9-32 years. We also determined the number and abundance of weed species in each field. Maize yield was not affected by the duration of organic management, although N input was approximately 35 % lower on organically managed fields. The number of weed species increased from 2 species in conventional fields up to 14 species in some organically managed farms. This study shows that maize yield was not affected by organic management on the investigated farms, while the biodiversity of weeds increased with the time since conversion to organic agriculture