We use a panel smooth transition regression model to investigate the influence of Conservation Reserve Program (CRP) rental rates on land enrollment under different crop price regimes. We employ a flexible estimation technique, allowing the CRP rental rate incentives to vary with crop prices, and construct a Hausman-type instrumental variable to address endogeneity. Simulations are conducted to assess the impact of varying crop prices on CRP acreage and its associated environmental effects. Results reveal a nonlinear relationship between rental rates and enrollment, with the impact diminishing as crop prices increase. A 10% rise in CRP rental rates corresponds to a 5.1% expansion in enrollment, reducing to 4.2% when crop prices reach a specific threshold. High crop prices lead to fewer acres enrolled, decreased carbon sequestration, increased phosphorus and nitrogen runoff, and increased sediment loss. Our findings highlight the importance of considering price fluctuations in conservation planning as it has significant implications for environmental conservation policies and programs.