Gypsum Overview: Calcium Sulfate Dihydrate (CaSO42H2O)

→ Download the USDA Gypsum Factsheet

Sources of Gypsum

Power Plants (Synthetic or FGD)

Recycled Dry Wall

Natural Deposits

Key Management Factors that are affected by FGD Gypsum Applications

Water Management Technique From the World of Scientific Research

  • Increase soil calcium and reduce magnesium.
  • Apply gypsum on the soil surface.
  • Increase aggregate soil particle forming & soil microbial activity.
  • Reduce surface sealing in order to allow for improved water & air infiltration into the soil profile (reduced ponding & improves oxygen exchange)

FGD Gypsum is a Nutrient Source

  • Approximately 20% Calcium ( ~400 pounds per ton)
  • Essential for cell wall health and strength
  • Approximately 15% Sulfur ( ~300 pounds per ton)
  • Essential for protein formation

Note: Gypsum is not considered a liming agent in most soils (except possibly in extremely high pH situations). It should not be viewed as a “substitute” for proper liming methods.

Soil Amending Properties

Acidic Soils: Provides usable Calcium to soil.

Alkaline Soils: Helps toxic salts leach out of the root zone.

FGD Gypsum is made from a neutral salt, however it will neutralize soil acidity caused by exchangeable Al+.

Gypsum applications can help mitigate the problems due to Sodium (Na+) and Magnesium (Mg2+) that may accumulate in soils due to the following,

  • Natural weathering processes
  • Use of poor quality irrigation water
  • Long-term application of dolomitic limestone  (Mg2+)
  • Parent Material make-up

Studies at the National Soil Erosion Laboratory,

West Lafayette, IN

Calcium and Gypsum Impact
on Water Infiltration (Norton

Chemistry Influences Soil

Good soil structure (aggregation) is enhanced by Gypsum application:

FGD Gypsum can be used to improve soil aggregation (structure) and inhibit or reduce soil dispersion.

Soil dispersion contributes to:

  • Surface sealing and crusting
  • Problems with seedling emergence
  • Run-off/Erosion ( FGD Gypsum reduces soil particle and nutrient displacement)
  • Subsoil swelling
  • Poor air/water exchange

In many areas we can source FGD Gypsum for you or provide you with a referral contact source. Please email us to begin the process or for a phone consultation. Pricing of material varies by source and geography.

We also have the opportunity to help a grower use Gypsum as a part of a system approach in improving soil and crop health. Please contact us to discuss these beneficial applications and methods.

Technical Questions and Answers Regarding the use of Gypsum Calcium Sulfate in Agriculture
(Gypsum Facts and Uses of Gypsum)

Can I use gypsum for fertility?

Gypsum analysis from FGD Gypsum sources (Flue gas desulfurization process) generally is approximately 18% to 21% Calcium and 14% to 16% sulfur. Both the calcium and sulfur can provide fertility to the soil and growing crops.

Where is there a gypsum supply?

Gypsum can be found from mined material, wallboard plants, and more broadly from Electrical Power Plants that use lime material to “scrub or de-sulfurize” flue gas in the energy making process. Gypsum in differing forms can be found in the United States as well as many other countries. It is advisable to determine what gypsum material has been approved for agricultural use as not all sources have received this approval.

Is gypsum board or gypsum drywall used in agriculture?


Gypsum from drywall or wallboard can be used in agriculture applications. Generally it is processed as refuse or “seconds” with regard to the board not meeting specs for drywall building use. In some cases, reclaimed drywall is can be used.  It is crushed and applied with a spreader.  It is advisable to research application equipment that best suits the application of the material. It is somewhat more difficult to spread than lime (calcium carbonate). A litter spreader or a steeper sided spreader with chain over belt setup is recommended to ease application. Check with your supplier for proper guidance.

What are uses for gypsum/gypsum uses with regard to agricultural gypsum?

Gypsum products are available in granular, pelletized gypsum, as well as bagged pelletized form and can be used as a soil conditioner or soil amendment. Gypsum calcium sulfate can be spread on the soil surface in order to provide sulfur and calcium to the soil for plant use as well as increasing the rate of infiltration of water and air into the soil profile. Calcium sulfate solubility is the scientific reason that it works to reduce soil particle dispersion.  Water breaks the bond easily to accomplish this. Thus, allowing surface water to infiltrate bringing oxygen with it.  Gypsum works on many soil types such as clay soil and loam soil. Research has show beneficial results for soil amending. Search the web for this technical information. Gypsum calcium sulfate uses and rates vary depending on specific applications with regards to the soil, crop and cropping practices. It is advisable to consult with a local agricultural consultant who may have experience with its uses in an a specific area.

What is/are gypsum pricing or gypsum prices?

Gypsum for sale can be found through gypsum wholesalers and/or gypsum retailers. The cost of gypsum varies widely based up supply and demand in a given area. It also varies greatly due to the actual location that you may find the supply. This is due to shipping costs of the material based on the bulk/volume and weight of the material. Rates of application vary from tens of pounds per acre to multiple tons per acre depending on need and uses for desired results. Soil amendment rates generally are higher than rates used for nutrient sufficiency. Consult a local agriculturalist who has experience or someone in their network who has experience with proper use in your considered application needs.

Contact us to find a source and purchase FGD Gypsum