A method for performing a soil analysis to determine quantities of one or more cations to be included in a soil treatment plan for an agricultural soil is described by either directly measuring or indirectly estimating the Zeta Potential of a soil sample. From these measurements or estimates appropriate quantities of water soluble cations (Ca, Mg, K, Na) can be determined and the Zeta Potential can be adjusted to a desired value. A method of estimating Zeta Potential is obtained from measurements of soluble and exchangeable cation concentrations, which are combined to generate Cation Relationship of Plants and Soil Solution (CROPSS) Value, and then through the use of a mapping relationship between a CROPSS value and Zeta Potential for reference soils, the CROPSS value can be used to determine the appropriate soil treatment to be applied that will adjust the Zeta Potential to a desired range or value.
