In this paper, a re-assessment of the aggregation problem in farm production functions is attempted. Aggregation starts from measurable farm management entities such as the milking cow, breeding ewe etc., and appropriate whole farm production functions are derived that are consistent with these biological units of farming, or as they will be called, the micro-functions of agriculture. The aggregate function, as derived, is based on the geometric means of micro outputs and inputs and could appropriately be said to 'represent' all the micro-functions. It is thus called, later in the paper, the representative production function for the farm firm.