CONTROVERSIES AROUND RESOURCE USE EFFICIENCY IN AGRICULTURE - SHADOW OR SUBSTANCE - THEORIES OF DEWIT,C.T. (1924-1993)

De Wit's (1992) thought-provoking article on resource use efficiency i n agriculture has evoked many reactions. De Wit maintains that most pr oduction resources ave used move efficiently with increasing yield lev els. It is not the concept of diminishing returns of Turgot or Mitsche rlich that counts in modern agriculture, but the more optimistic law o f the optimum of Liebscher (Journal fur Landwirtschaft, 43, pp. 49-216 ). Unlike many agronomists and economists, de Wit maintains that inten sification of production is beneficial for the environment, the farmer s' community and society at large. However, it appears that controvers ies around concepts on biophysical input-output relations and intensif ication ave shadow rather than substance. Even where certain principle s on input-output relations apply may the practical consequences of th ese same principles in a broader context ask for considerations not al together compatible with rigid academic notions. Finally, in order to tackle agro-ecological problems mole adequately, the persistent incomp atibility between technical and social scientists needs acute attentio n.