In comparison with the amount of energy supplied by solar radiation for crop production, the amount of energy supplied by mechanical means is relatively small. The importance of the mechanical energy supplied by tractors and machines lies in its contribution towards the control of the growth process. The main trend in mechanization is for tractors and machines to become bigger and more powerful which in the farm structure of Western Europe leads to a mismatch between the capacity of the machines and the size of farms. Modification is regarded as more likely that innovation. Modifications in design, management and farm structure are discussed. The principal challenge of innovation is seen as the one of scale in the use of power. A small tractor using a degree of automatic control is proposed for the 15 to 100 ha farms which form the majority of holdings in the E.E.C. Automatic feeding and recording systems for livestock units on such farms are also proposed.