There has been an historical tendency to assume that labour productivity grows less rapidly in agriculture than in the manufacturing sector, partly because there is less scope for benefiting from the division of labour. Indeed dual models of transition, such as the Lewis Model (Lewis, 1954) typically contrast a stagnant traditional rural sector with a dynamic and modem manufacturing sector. However, this view has been challenged by others, who have observed rapid science-based technical change in agriculture (for example, Hayami and Ruttan, 1985).