Calcium Products - Andrew Hoiberg, Ph.D.
Calcium Product 98G


Andrew Hoiberg, Ph.D.

Andrew Hoiberg, Ph.D.

What does all this rain mean to your field?


Obviously, it’s been a cool, cloudy and wet spring. So much so that corn planting, as of last week, stands at only 88%, 11% behind the five-year average of 99%. Only 44% of the soybean crop has been planted, way behind the 99% we experienced last year at this time. The stark weather contrast between this year and last has not only limited farmers’ ability to get into their fields, but also may have consequences in regards to soil fertility.

During drought conditions, it is normal for a ‘bank’ of nitrogen to be stored in the soil as there isn’t sufficient moisture to move it in the soil, so it stays put. Soil samples taken by Iowa State last fall indicated that it may be possible to have upwards of 100 lbs N/A carryover to this season, which is roughly double what may normally carry over from year to year. However, with all of the moisture that has fallen this spring, a significant amount of that nitrogen may have already leached out of the soil.

My suspicion is that the same thing may be happening with sulfate as well. Observations that I’ve made as I drove past corn fields last week generally show a yellowish, chlorotic plant that is starved for nutrition, at the V3-V6 stages on average.

The Iowa Soybean association is recommending farmers do a late-spring, pre-sidedress soil nitrate analysis in early June when the plants are 6-12 inches tall. The benefit of this test is that it predicts the amount of nitrogen available before the corn plant begins taking up more nutrients as it matures. ISA is recommending that if the test shows less than 21ppm nitrate, there is a high probability that the cost of an additional nitrogen application would be covered by the increase in yield you will see from that application. It’s completely up to the individual, but it may also be worthwhile to consider a sulfate source to sidedress along with additional nitrogen.

There are other compounding factors when soil is waterlogged for prolonged periods. Not only does the saturated soil predispose corn and other plants to disease pressure, it depletes the soil of oxygen, which has many negative impacts on plants. One of which tends to be exacerbated when it happens early in the season is restriction of root growth and development. Fortunately, we are not dealing with temperature extremes along with the saturated soil which would make the situation even worse. Things look to warm up this week; hopefully the soil will start to dry out a bit so we can all get back to our regularly scheduled growing season!





Gypsum: Source, purity, and particle size matter

The goal of putting a product on your turf is to realize the benefits of that application as soon as possible. Paying for a product that may take years to work just doesn’t make sense. People may argue that gypsum is gypsum, but in reality that’s not true.

There are multiple forms of gypsum: calcium sulfate dihydrate (true gypsum), calcium sulfate hemihydrate (bassanite), calcium sufate anhydrite (anhydrite gypsum), and synthetic gypsum, which is a by-product of scrubbers at coal-fired power plants that force sulfur exhaust gas to combine with calcium carbonate (limestone) to form synthetic gypsum. Within most products on the market that are true gypsum, there can be differences in the purity and particle size distribution, which matters when it comes to getting the most effective product for your turf.

Dissolution of a gypsum product into the soil/water matrix is an extremely important indicator of how the product will react. The two biggest Gypsum Dissolutioncharacteristics that determine how soluble a gypsum product will be are 1) its chemical composition—true dihydrate gypsum will go into solution much quicker than hemihydrate and anhydrite products, and 2) its particle size distribution. If you are comparing two dihydrate gypsum products that have the same purity, it’s true that their chemical makeup is the same; however, if one of the products has much finer particles as a result of its processing, it will go into solution in the soil much faster than the coarser product (which may not ever go fully into solution).

As for synthetic gypsums, there can be undesirable levels of heavy metals in these products depending on which scrubbing system was used and where the product originated. This variability means that you may not be getting the same product each time. You wouldn’t buy a fertilizer that was inconsistent from batch to batch, so why do the same with your gypsum source? There is no one source for synthetic gypsum, so it pays to be wary about how consistent and potentially harmful these products can be to your turf.

SuperCal SO4 (true dihydrate gypsum) comes from one of the purest sources of gypsum on earth and is ground finer than any product on the market prior to pellitization, which results in the highest dissolution rates in the industry. What does all of this mean? It means that SuperCal SO4 goes to work for you as soon as water hits the pellets, and compared to other products that have a wide range of particle sizes, you can put on much less of our product and get the same results. Relying on old application rates that have no scientific basis is not the right way to approach gypsum application. Consulting with our trained staff will get you the right application rate for your situation.

The pelletized nature of SuperCal SO4 makes it much more compatible with turf spreading operations, and it can be mixed with any of your other dry fertilizer products to limit fill ups and labor. Lastly, SuperCal SO4 is 100% organic and is OMRI certified, which fits well into golf course maintenance programs that are trying to be environmentally sensitive to the wildlife and bodies of water found there.









Is it SuperCal 98G or SuperCal SO4?

SuperCal 98G and SuperCal SO4 can often be confused. From their similar names to the similar nature of their appearance, people wonder, how do I know which product I have?

The vinegar test is a simple test you can perform quickly and easily to know whether the product you have is SuperCal 98G or SuperCal SO4.

The acid neutralizing reactions between the carbonate and acid in the vinegar will cause SuperCal 98G to fizz. Since there is no carbonate in SuperCal SO4, it will do nothing.

Combine no more than 1 teaspoon of pellets and a 1/4 teaspoon of vinegar in a reaction proof container with an open top. 



SuperCal 98G is on the left, with its tell-tale fizzing. That is a result of 1 ml of vinegar and 1 tsp of each product. SuperCal SO4 is on the right, no reactions.



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