Résumé
Substantial initiatives are under way in the tropical world to develop and promote direct-seeding mulch-based cropping systems (DMC) in order to reduce soil erosion and improve crop nutrient and water balances. DMC have been adopted by large-scale mechanized farmers, especially in America and Australia, but seldom by resource-poor farmers in the developing world. This study was conducted in Vietnam with the aim of evaluating the feasibility of farmers’ implementing DMC in a mountainous area. The method involved simulation of rational households maximizing their income subject to food security constraints and availability of resources. It generated insight into why farmers of a small region were reluctant to adopt DMC due to the extra labor and input required to implement these techniques during the first years, which hampers their economic performance. In another region, under different biophysical and economic environmental conditions, the study showed that DMC were more likely to be adopted provided that possible constraints at the community level are overcome. The method also allowed us to discuss the types of technical improvements that would make DMC more attractive to farmers. For most farm types, labor required by mulch establishment would have to be reduced by more than 30%. This would mean spreading much less biomass than the 7 t ha−1 currently necessary, compromising the weed-control function of mulch. This would be technically feasible only by using herbicides but this would not be economically sound since it would increase cash requirements. The study showed that subsidies of 50 to more than 200 USD ha−1 were necessary to enable the conversion of all conventionally managed sloping land into DMC in the simulations. These amounts are high relatively to gross margins (250–750 USD ha−1) under conventional management