AREAS in which white clover grows reasonably well have the potential of carrying a certain stocking rate without using fertilizer nitrogen. The development of dairying in such areas will logically use the best available legumes to increase stock carrying capacity to its economic optimum. Evaluating the place of fertilizer nitrogen in these areas will therefore be concerned with the establishment of the maximum economic production from legume-based pastures, and secondly with the increase in production per unit area possible using a range of nitrogen levels. Where the research objective is to provide guidance to a developing. industry, the optimum production from both nitrogen' sources must be defined using available information on the best management systems, most suitable .legumes, most effective rhizobium, etc. This approach accepts that new information on any of the factors involved could increase the stocking rate which gives optimum production from either nitrogen source and would advocate that some of the research resources should be used to examine such management factors. If this guidance is not available, decisions will still have to be made by the industry but at greater risk (Morley and Spedding, 1968).
