The study investigates the value of additional information on the response function to soil salinity of a given crop (potatoes), with regard to a stochastic long-run optimization model for utilization of saline water in a single-farm framework. The analysis provides a conceptual and methodological framework for investigating the expected value of sample information (EVSI), as well as an efficient tool for empirical application. Although a few approximations have been used, the results provide an estimate of EVSI and indicate the need for additional information.