In most West African countries, agricultural production is a complex process that involves multiple household members managing land and sharing agricultural inputs. We develop an intrahousehold decision-making model to illustrate how technology adoption can influence bargaining processes on farms in harsh agricultural environments of West Africa, where staple food production by extended families is organized collectively under the leadership of a senior head. The head, who assumes primary responsibility for household food security, also allocates fields to members who manage production individually. Drawing on this and the intrinsic complementarity of labor and fertilizer as divisible inputs, we test the nature of the linkage between fertilizer use on collective and individual plots by applying bivariate probit and tobit models to nationally-representative, panel data from Burkina Faso. We find evidence of input sharing, though bargaining is inadequate to sustain efficient allocation of fertilizer. Plot manager characteristics that influence bargaining power, such as literacy, gender, age, contact with extension, and membership in farmer organizations differ between collectively- and individually-managed plots-confirming the differential status of household members in technology adoption. Agroforestry practices are strongly and positively associated with fertilizer use, regardless of plot manage type. Programs aimed at increasing use of modern agricultural inputs should consider impacts on bargaining positions within the household. Providing inputs to women and young men will increase their influence on other decisions, which may lead to greater equity within the household. It may also enhance efficiency in production, since currently, inputs are not allocated efficiently within the household.