The close links between agricultural and economic growth in the low income countries of sub-Saharan Africa during a decade of ‘crisis’ has prompted a widespread theoretical and empirical reappraisal of the dynamics of agricultural sector performance in such countries. A common thread running through this reappraisal is the observation that falling agricultural productivity reflects the widespread degradation of the resource base. As Pearce, Barbier and Markandya (1988) put it: ‘Africa’s economic crisis certainly appears to be largely due to Africa’s agricultural crisis’, and ‘Africa’s agricultural crisis is in significant part an environmental crisis’. A variety of explanations for the trends that underlie this ‘crisis’ are offered in the literature. The dominant view, however, is that the causes of an ecologically unsustainable use of agricultural resources are to be found in the economic environment within which farmers make their decisions (Repetto, 1986 Repetto, 1989; Warford, 1989; Lutz and El Serafy, 1989; Barbier, 1989b).