Socio-economic assessment of the impact of adoption of conservation agriculture (CA) on farming systems in the region of lake Alaotra, Madagascar

Conservation Agriculture (CA) was introduced at the lake Alaotra, in Madagascar, in a context of yield drop and silting-up of rice fields in the low lands. Land tenure pressure linked to the attractiveness of the area leads to the colonization of surrounding uplands, very sensitive to erosion. Conservation agriculture deals with a double constraint: i) increase household income ii) preserve natural resources. This study assesses the economic impact of CA systems on the income of modelised representative farm holdings for each area, through a prospective analysis in the midterm, 10 years. The processing of the databases from the diffusion operators has highlighted a light increase of yield according to the age of CA systems. These systems also have a buffering effect on climate hazards. Parts of CA systems diffuse spontaneously within farming systems. Surveyed cropping systems have been deeply modified by the effect of BV-Lac project; the smallholder's population at the lake has innovative practices. Modeling has highlighted that CA systems improve significantly net farm income at plot scale in the midterm. The results are not as clear at farm scale. Indeed, the higher the farl income generated by irrigated or PWC rice fields is, the lower is the impact of CA systems on farm income. For farm holdings with few irrigated rice fields, CA systems insure the income by stabilizing and improving yields of rain fed crops. (Résumé d'auteur