How it works

GYPSOIL alters soil chemistry.  Soil particles and organic matter have negative charges on their surface molecules.  Mineral cations (with positively charged surface molecules) are attracted to these negative charges on the soil particles. The strength of the attraction is called the CEC.  This is an indication of the level of nutrients.  Clay soils tend to have a high CEC.

GYPSOIL is calcium sulfate (CaSO4 2H2O). It dissolves (dissociates) with moisture into calcium and sulfate. The sulfate (SO4) attaches to excess magnesium (Mg) on the soil surface molecules, making soluble Epsom salts which flush down out of the soil profile. The remaining Ca then replaces the Mg on the soil particle.  This is what sets the stage for improved soil structure.

Soil Structure

Influence of calcium

Calcium is a positively charged ion called a cation.  Cations are absorbed by the plant roots and also held on exchange sites in soils. The positive charge of calcium is attracted to negative electrical charges found on the exchange sites on clay particles.  The more clay, the stronger the attraction.  This attraction of the positive Ca with the negative charges in the clay particles -- binds the clay soil particles together so they become flocculated and resist dispersing and soil structure breakdown.


Cation Exchange Capacity or (CEC) is an indication of the volume of nutrients that can be held by the soil.  One easy way to think of CEC is how big a barrel the soil has to hold nutrients.  The more organic matter and clay in the soil, the greater the CEC and the more nutrients can be held in it.   Sandier soil typically has a lower nutrient-holding capacity and lower CEC.  Trying to put ten gallons of nutrients into a five-gallon storage means nutrients will go to waste.

Cations are elements with one or more positive charges.  Clay and organic matter are covered in negative electrical charges called exchange sites.  Cations are attracted to and hold onto negative exchange sites.  The amounts of different cations vary between soils. Generally, higher CEC soils require higher rates of GYPSOIL for soil amendment benefits. View our recommended application rates for GYPSOIL.


OSU GuideSoil scientists at Ohio State University have completed a comprehensive field guide on the use and benefits of gypsum. To learn more click here.

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