Using field‐level data, we investigate whether traditional land tenure systems are an impediment to allocative efficiency in Niger. We find that yields are strongly influenced by the manpower available to farming households, an indication that marginal returns to labor and land are not equalized across households. We uncover no relationship between manuring and whether or not local customs allow land sales. But manuring is influenced by tenure security: farmers who cultivate both borrowed and owned fields divert manure toward the latter. Our findings do not imply that a change in land tenure system is called for.