Concern about the increasing degradation of natural resources in developing-country agriculture has led to the development of impr systems that make use of biological processes to promote production in a sustainable manner. The paper uses a case study on the adop of Mucuna (Mucuna pruriens var. utilis) to examine the farmers' perceptions and dynamics in the adoption of such improved sy Small-scale farmers ranked Mucuna fallow more highly than chemical fertilizers because of its weedicide effect, long-term improvem of soil fertility, low cost, and ease of availability at the village level. The grass roots extension organizations played a significant the dissemination of Mucuna. The removal of incentives to adopt did not adversely affect the trends in the spread of the technology. H farmers consider insecure land tenure a constraint to adoption for (even) this non-perennial species.