Abstract

Crop diversification helps maintain yields while reducing pesticides’ and fertilizers’ use. Despite extensive support for this practice among agronomists, crop diversity remains more limited than what we can expect from technical benefits to specialization. We study barriers to diversification that can arise from farmers’ equilibrium choices. Farmers choose their land allocation across two crops, where one is intrinsically more productive than the other. A congestion effect arises: the productivity of each crop decreases when its proportion increases. We investigate whether the crop with the highest achievable yield over-dominates or not, first for a single farmer and then under spatial congestion. Mental accounting, lack of coordination and non-internalization of spatial effects, help understand under-diversification. This under-diversification can arise even though we consider only the monetized value of diversity (e.g., its impact on yields) and neglect other social benefits.

Co-author : Stéphane Lemarié

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