This article solves and characterizes optimal decision rules to invest in irreversible land improvements conditional on land tenure insecurity. Economic model is a normative dynamic programming model with known parameter for the one period returns and transition equations. The decision rules are solved numerically conditional on alternative scenarios on the likelihood that the lease contract and, thus, farmer access to land is either renewed or expires. The model parameters represent Finnish soil quality and production conditions. The results suggest that irreversible land improvements decrease quickly and the yields decline gradually when the farmer is confronted with land tenure insecurity caused by uncertain renewal of the lease contract.