Gypsum (calcium sulfate): how it can make degraded soils productive again

Soils in the world degrade generally from human induced activity like logging, mining, drilling (for oil or natural gas), accidental spills or farming. However, nature can also degrade soils with changes in landscape and water levels.

Global Soil Degradation
Global Soil Degradation

Once soils are degraded, they are no longer productive. They cannot support natural vegetation or soil life. These soils can be remediated, but it takes effort, time, resources and a strategy. Soil remediation aims to reduce contaminants to levels which are suitable for reuse. This means a site can be reused without environmental risks or risks to human or other organisms that inhabit this planet.

Soil remediation is a term describing various strategies that are used to remediate and revitalize soil. Remediation deals with the removal of pollution or contaminants from the soil, groundwater, sediment, or surface water. Remediation protects the general environment and most importantly, returns it to a natural state of agricultural production. Some of the removed pollutants can be hydrocarbons (petroleum), heavy metals, salts or rocky parent material.

Soil degradation is caused by a lot different things. A host of technologies is available for correcting the problem based on the nature of the contaminant. Gypsum (calcium sulfate) can play a role for both industrial and agricultural remediation.

Soil remediation depends in part on soil biology that can do wonders to degrade carbon-based contaminants and rebuild soil structure and health. Gypsum can help improve soil structure and create a better environment for soil biological activity.

Gypsum is also an excellent choice for remediation of salinity and soils high in sodium and contaminated by salt brine. Salts and brine impact the soil by:

  • Dispersing soil particles, which destroys aggregation
  • Reducing the plant’s ability to take up water (osmotic potential)
  • Impeding a plant’s ability to take up necessary nutrients

Salts are just ionic forms of minerals in soil water. Sodium, also a salt, has an even greater impact on soil. When sodium reaches high levels in soil, it can cause:

  • Reduced infiltration
  • Loss of soil structure
  • Reduction in pore space
  • Reduced air and water movement
  • Reduced biological activity
  • Reduced mass flow of nutrients with water
  • Increased runoff and erosion

Gypsum helps disperse the soil for better aeration, drainage and water infiltration, which is the first step in remediation. The calcium in EcoGEM® gypsum dihydrate (CaSO4 + 2H2O) replaces sodium on the exchange complex, allowing the soil to be washed out with water.


Dr. Davidson posts articles on soil management and subjects to gypsum. If you have suggestions for topics or questions, feel free to contact him at [email protected] or call 402-649-5919.