Bringt „Öko“ mehr Humus? Einschätzung der aktuellen Humusbilanzen der ökologisch und der konventionell bewirtschafteten Ackerfläche in Deutschland

We calculated humus balances for organic and conventional cropland in Germany and compared them to each other in order to find out whether organic farming comprises a better humus reproduction than conventional farming, as commonly assumed. Applying a dynamic humus balance model that was parametrized based on data from agrostatistical reports we yielded comparable balances for the two farming systems. The reason was mainly a considerably lower stocking on organic farms, and the low N supply. However: a superior cropland structure brought the balance to the same level as with conventional agriculture despite of these factors. Due to shortcomings in model parametrization caused by the available data base, results may not be over-interpreted. Still, it can be concluded that the promotion of humus stocks in arable soils is not a label effect of organic farming, but requires active management, especially with the present specialization trends