All calcium sources are the same, correct? For years we have been led to believe that the choice of calcium should merely come down to price, all other things being equal. A recent report from Dr. Larry Stowell of PACE Turf Research reveals that substantial, if not extreme differences, exist among calcium sources.

For instance, both calcium sulfate dihydrate (the true form of gypsum) and calcium sulfate anhydrite are calcium sulfate sources.  However, the dihydrate form has two water molecules associated with the calcium sulfate whereas the anhydrite has no water. This characteristic difference greatly impacts the degree of calcium solubility in water between the two sources.

In laboratory tests evaluating the solubility of the two sources, approximately 25% of the calcium from calcium sulfate goes into solution within an 18 hour time-frame. Conversely, the true gypsum ends up with more than 85% of the calcium in solution, which translates to 3.5 times more calcium going into solution compared to calcium sulfate anhydrite. The significance of solubility is that calcium only performs to reduce sodium build-up and provides calcium nutrition to plants when it is solubilized into it’s Ca++ ionic form.

Another factor in the rate of solubilization is how finely ground the materials are milled prior to pelletization. The finer the grind, the greater the surface area at which the materials are exposed to water. This increases the rate at which the materials solubilize.

With these important considerations in mind, Simplot Partners developed TruGyp to be a superior quality granulated gypsum product with the following characteristics:

• Superior solubility of the calcium
• Highest purity of gypsum (95% minimum purity)
• Extremely fine milling before product is granulated
• Supreme quality/uniformity of the product granulation
• Rapid dispersion of granule once water is applied