Synthetic Gypsum Application

This past week, MCC applied gypsum (CaSO4/2H20) to its fairways, aprons and problematic areas of the intermediate rough.  Gypsum is applied to alleviate the effect that sodium bicarbonates (NaHCO3) have on soil structure.  In high enough concentrations these bicarbonates will "crust over" the soil, significantly limiting water infiltration and root penetration.  Sodic soils are uncommon in Michigan but MCC's irrigation source does have a high level of sodium bicarbonates, and when the irrigation system is used extensively (as it was in the summer of 2012) negative effects on the soil are noticeable.

Specifically in MCC's soils; The Ca is replacing Na (sodium) bonded to clay particles, alleviating poor soil structure.  Also of note, elemental hydrogen is a product of this reaction.  Gypsum is not a liming agent and will not raise pH. 

Synthetic gypsum is a bi-product of pollution control methods utilized at some coal burning power plants.  In an effort to reduce sulfur dioxide entering the atmosphere (a constituent in acid rains), the flue gasses are passed through a slurry of hydrated lime and calcium sulfite is formed.  The CaS03 is than oxidized resulting in CaSO4 (gypsum) and washed with water to filter out contaminants such as Boron and Mercury.  The end product is a fine textured, cheap, relatively pure source of gypsum. 

What advantage does this new synthetic gypsum have over the original mined sources?  A common complaint by turf professionals is that the mined gypsum variation in particle size makes applications difficult. Large particles could not pass through the feeder holes in fertilizer spreaders.  Synthetic gypsum does not have this drawback and applies especially well when a Ty-Crop or Turfco Topdresser are utilized. 
Another point in synthetic gypsum's favor is its small percentage of insoluble residue, less than 1%.  Regular applications of gypsum have a large percentage of insoluble residue (up to 19%) and take a relatively long time to work its way into the soil even with irrigation and rain events.  The residue left behind can become quite messy and is smeared and picked up by reels, carts and even walking golfers.  The synthetic gypsum recently applied by MCC (3 days prior to the publication of this article) has almost all been washed into the soil profile, a huge improvement over the couple of weeks necessary to incorporate mined gypsum into the soil.  Purity is another issue, with mined gypsum having the potential to host a variety of different elements as opposed to the minute percentage of impurities found in synthetic gypsum. 

Even distribution during application

Synthetic gypsum is still a relatively new product, not utilized by many major golf courses and therefore research based comparison is not as available.  However, due to its physical properties and low cost (relative to mined gypsum) there will be a higher demand and therefore more researched performed on the substance.  Empirical evidence will soon follow, and we will keep our readers posted on the subject.  Enjoy.