N2O-emissions following long-term organic fertilization at different levels

The effect of C- and N-enrichment of agricultural soils by long-term organic fertilization was tested using three field experiments about different fertilizing strategies with organic components. Beside increased microbial activity and N-mobilisation a promoting effect on N2O-release was found. The order of this effect appeared modestly compared to the direct, immediate effects of applied mineral nitrogen from organic or mineral fertilization. Total N2O-losses were determined by the temporal pattern of N-fertilization, cultivation and the climatic conditions. The decisive attribute of organic fertilizers about their liability to increase N2O-emissions was their content of mineral or rapidly mineralizable nitrogen.