Gypsum vs. mined calcium sulfate anhydrite for sodium management

Permalink | Cultural,

In the August 31, 2009 Super Journal report, "Gypsum vs. mined calcium sulfate anhydrite for sodium management" (263 KB pdf document), a study was conducted evaluate the ability of two calcium sulfate based products – gypsum (calcium sulfate dihydrate) and mined anhydrite (calcium sulfate anhydrite) to reduce soil sodium levels when applied to Poa annua greens prior to leaching. Key conclusions were:

• Leaching of both treated and non-treated greens resulted in significant reductions in soil salinity, sulfur, chloride, magnesium, potassium, sodium, sodium percentage and nitrate.
• One application of either mined anhydrite or gypsum at 10 lbs product/1000 sq ft did not result in further reductions in soil salts or sodium, or in an increase in soil calcium or sulfur. It was simply leaching, whether on the treated or non-treated greens, that provided the only significant reductions in soil salts.
• The lack of observable effects caused by the application of either the mined anhydrite or gypsum has several possible causes. These include the possibility that:
• the products are not effective under these conditions due to low solubility or other issues
• the 10 lb product /1000 sq ft rate tested, which is the rate recommended on product labels, is too low to produce statistically significant changes when used in a single application
• leaching overwhelmed the effect of the product by moving all salts below the sampling area
• To follow up on the possibility that solubility was involved in the observed results, we obtained samples of commercial products based on gypsum (Allied Gypsum and Ultra Fine AG Gypsum Soil Conditioner), mined anhdydrite (Cal-CM Plus Mini-Prilled) and on an uncharacterized source of calcium sulfate (Cal-Sul) for analysis. Results of solubility tests clearly demonstrated that Cal-CM and Cal-Sul were much less soluble than the two gypsum products tested. While the low solubility of Cal-CM and Cal-Sul raises many questions about their potential as soil or water remediation tools, it is not the sole cause of the observed lack of efficacy in the field, since the highly soluble gypsum products also had no effect on soil salts or sodium.
• To follow up on the possibility that use rates were too low to produce detectable results, follow-up field tests will be conducted
• Until results from planned field tests confirm the optimal rate and use patterns for calcium sulfate-based soil amendments, the benefit of these applications for sodium management cannot be determined. For the time being, the best tool for reducing sodium and other damaging soil salts on turfgrass is leaching

Project title: Evaluation of gypsum and mined calcium anhydrite as pre-leaching soil amendments for sodium management on turfgrass

Principal investigators: Larry Stowell, Ph.D., CPAg and Wendy Gelernter, Ph.D., PACE Turf, LLC

Cooperator: Kevin Hutchins, Mission Viejo Country Club, Mission Viejo, CA

Report (263 KB pdf) posted 8/31/09

Changes in soil chemical factors following rainfall and calcium chloride applications

Permalink | Cultural, Soil,

As detailed in the Super Journal report, "Changes in soil chemical factors following rainfall and calcium chloride applications" (24 KB pdf document), calcium chloride, when applied during rainfall periods, can have a positive effect on soil quality, especially in high sodium soils (greater than 110 ppm and 6% of the total extractable cations) that also have excessive sulfur (greater than 800 ppm for ryegrass overseeded bermuda fairways). The potential problem of accumulation of chloride in the soil was not an issue under these conditions. The fact that overall soil salinity was not significantly reduced indicates that either more rain and/or additional applications of calcium chloride will be required before overall salts are reduced.

Project title: Changes in soil chemical factors following rainfall and calcium chloride applications

Principal investigators: David Major and Scott Dey, Shady Canyon golf Club, New Port Beach, CA

Cooperators: Larry Stowell, Ph.D. and Wendy Gelernter, PH.D., PACE Turf

Report posted 3/9/09

Evaluating USGA’s TruFirm for greens firmness measurements

Permalink | Cultural, Precision Turf Management,

In our continuing efforts to develop programs that assist turf managers in maintaining optimal greens firmness (545 kd pdf), we have followed with interest the USGA's TruFirm. This tool was developed by the USGA to recreate the effect of golf ball impacts, thus assisting in preparation and monitoring of greens for consistent tournament play, day in and day out.

To this end, we were lucky this past January to be able to team up with USGA agronomist Pat Gross and Victoria Club superintendent Mark Burchfield to take a preliminary look at the TruFirm, and to compare the picture it gave us of greens firmness with that provided by the Clegg Impact meter.

As detailed in this Super Journal report (311 KB), there was a good correlation between the two devices. However, further work is needed to identify the potential role of each of these tools in greens management programs.

Project title: Measuring greens firmness using the USGA TruFirm and the Clegg Soil Impact Tester at Victoria Country Club: A preliminary study

Principal investigators: Larry Stowell, Ph.D. (PACE Turf), Pat Gross (USGA), Wendy Gelernter, Ph.D. (PACE Turf) and Mark Burchfield (Victoria Club, Riverside, CA)

Report posted 2/16/09