In the oil palm agroforestry system on the Adja Plateau (West Africa), land titling plays an important role. Landowners argue that oil palm fallow (dekan) restores soil fertility, but in the long-term it is also an instrument in the struggle for control over land. A land-titling programme in the study area allowed an analysis of the relationship between titling and soil fertility management that showed two different institutional effects with socio-technical consequences. Titling increased land security for landowners and, although this security initially reduced access to land for tenants, a subsequent introduction of witnessed paper-based contracts enhanced tenants' access to land and improved their security of tenure. Improved titling and more secure tenure reduced conflicts over land and opened possibilities for agricultural intensification. This change was associated with a shift from long-term oil palm fallow to shorter-term land-management practices where tenants and landowners increasingly invested in land through rotations between maize and cowpea (rather than maize mono-cropping) and the use of mineral fertilizers, without increased use of household waste (organic amendment). The paper suggests that sustainable agricultural intensification in agroforestry systems requires institutional changes, based on a mixture of customary and formal rules, in both landownership and rental agreements to access land.