The starting point of the paper is the fact that the economic effects of field crop operations is highly conditioned by energy prices (primarily diesel fuel prices) as well as by the raw material whose prices to a large extent depend on energy price (fertilisers). Hence, it is determined on the basis of the model of family farm (specialized in field crop production) that the change in the prices of the given inputs influences the change in gross margin and farm profit. A special attention is paid to the changes in gross margin per worker and per working hour, as well as to the profit per worker and per working hour, which is caused by a varying of the purchase prices of raw materials, whose prices depend on energy prices (diesel fuel and fe...