ProCal40 Gypsum

PRO CAL 40 is 99.5% pure calcium sulfate and has a consistency similar to talc making it very reactive in the soil.

It benefits soils through enhancing soil structure, improving water penetration, increasing nutrient availability, enhancing root growth, raising air/water exchange, reducing ill effects of sodium, magnesium and bicarbonates, providing a plant available form of calcium and sulfur, etc. Using PRO CAL 40, we have experienced positive yield benefits in alfalfa, corn, forage grasses, potatoes, soybeans and wheat as well as most vegetable crops. Yield increases in alfalfa often exceed 1 ton/acre, corn and wheat yields have been enhanced 10-30 bushels per acre and soybean yields are usually 4-10 bushels better. Economic returns usually exceed $8 for each $1 spent over the life of the product (3 years).

Calcium Sulfate in the form of PRO CAL 40 is unique in that it can perform in all three categories of soil treatment. As an amendment, a conditioner, or as a fertilizer.


Soil Amendment

Alkali Soils
As a soil amendment PRO CAL 40 is the preferred product for reclaiming sodic or alkali soils since it provides calcium for releasing the sodium and sulfate sulfur for leaching it out of the root zone.

Acid Soils
PRO CAL 40 has also been used in acid sands as a liming material by providing a more soluble form of calcium to the acid subsoils. Under normal conditions, however, calcium sulfate has little effect on raising pH.

High pH Soils
In soils with high pH’s (> 8.0) bicarbonates and carbonates increase (either from irrigation water or from subsoil drainage). Calcium Sulfate is an excellent and inexpensive source of soluble calcium that will react with the carbonates to form lime. This, in turn, lowers the pH.

Soil Conditioner

As a soil conditioner PRO CAL 40 has been proven to improve soil structure by providing calcium as a binding agent to improve aggregation of clay particles and to increase microbial activity which in turn provides “glue products” that hold soil particles together. Soils become more friable and top soil becomes deeper.

Soil Fertilizer

As a soil fertilizer, PRO CAL 40 provides almost equal amounts of calcium (23%) and sulfur (17%). Sulfur is mobile in the soil, however, PRO CAL 40 slowly releases its sulfur making it available over many years. PRO CAL 40 is an excellent slow release source of calcium as well. Even in high pH soils soluble forms of calcium can be low due to the propensity to form lime materials.


In Iowa, PRO CAL 40 and NutraBio are registered with the Department of Agriculture as liming materials. Regulations prohibit Soil Solutions from marketing either of these products in the state of Iowa as having any other qualities or benefits other than its value as a liming material. Although this website may list other benefits and features of these products we are not allowed to market PRO CAL 40 or NutraBio based on these benefits in Iowa.

If you have any questions please feel free to contact us.

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