(Results from long-term field experiments concerning soil fertility preservation)

Abstract

For 45 years, long-term field trials have been carried out at Groß Kreutz in the province of Brandenburg. From that, substantial findings have been derived regarding the demand of organic matter and the reproduction of soil fertility at sandy soils. The optimum magnitude of yield has also been established for local conditions. On that and other basis a method has been developed to calculate balances regarding soil organic matter. In an application of the method it has been demonstrated that straw should stay on the fields in order to secure humus reproduction in the province of Brandenburg. The natural yield potential established in long-term field trials on these sandy soils was 60 to 80 dt dry matter per ha. This is equal to the results presently reached in Brandenburg. If the main crops are grown, a fertiliser input of 100 to 130 kg N per ha leads presently to a deposit of 70 to 90 kg N/ha due to removal of plant material.