Some cations will have a preference over others for the negative surface charge of a soil colloid. In general this will be related to the charge of the cation and its hydrated radii . In other words the greater the charge the greater the force of attraction and the greater the distance between the charges the lesser the force of attraction. Therefore, in order for many highly weathered soils to be productive from an agricultural standpoint we must lime them to increase their base saturation. The first farmer in the USA to recognize the importance of lime was a Virginia Farmer named Edmond Ruffin who used oyster shells on his fields.
Today there are a variety of liming sources available to farmers.
Pay careful attention to the stoichiometry of the reaction. Remember that the actual reactions represented in the above demos are much more complex in natural environments. Understanding charge development and CEC of soils allows us to better manage our soils for crop production and understand the bioavailability and mobility of contaminants in the subsurface.