Soil pH has been described as the “master soil variable” affecting soil fertility and crop health. On the Canadian Prairies, soil pH varies at regional and field scales. In this session, the  following topics will be explored: 1) causes of soil pH variability and changes in soil pH; 2) best practices for soil sampling and measuring soil pH; 3) what values of soil pH are considered optimum, too high or too low; and 4) what can be done if soil pH is too high or too low.