Betriebliche Stickstoffkreisläufe bei unterschiedlichen Konzepten der Landbewirtschaftung und Einflußbereiche für technische Mittel

Analyses of matter fluxes allow to determinate and evaluate turnovers in farms with consideration of all quantifiable mass flows. The methodical approach to such analyses is described on the example of the nitrogen flow in farms differing in production structure and farming practice. The results of N-balancing are rated by means of reference values for ecologically tolerable N-issues and environment-related N-flows A comparison of farms differing in their production structure shows that the nitrogen efficiency is essentially influenced by livestock numbers per area. Increasing animal rates reduce the nutrient removal by market products due to a limited nutrient transfer to the animal products. Along with this, the nitrogen quantities remaining in the farm circuit as well as the N-loss potential on farm go up. The actual soil-N quantities amounted to 30 kg·ha^-1 in ecologically managed farms and up to 100 kg·ha^-1 in conventional systems The total N-utilization on farm level reached 18 to 45% of the external N-input A better revelation of reduction potentials by process design and technical equipment would require that precise coefficients and algorithms adjusted to the applied technology be integrated into the model.