Abstract
In this paper, nitrogen cycling of group farming systems by dairy and crop farmers was analyzed using compartment models for nitrogen flows in the systems. In particular, the effects of crop utilization on nitrogen cycling in the systems were examined by simulation. The following results were obtained from the analysis.1. There was a remarkable relationship between the number of cows per field area and nitrogen cycling in the systems.2. Nitrogen cycling was largely influenced by the ratio of paddy rice field to total faming land, feed crop yield and nitrogen losses in process of manure production in the systems.3. The nitrogen cycling and nitrogen use efficiency of group farming systems in Chugoku region were less than those of farming systems in overall Japan in spite of the fact that the number of cows per field area was smaller in the former systems. This result may be caused by larger paddy rice field and less crop yield in group faming systems in Chugoku region.
