Managing sodium with calcium chloride

May 30, 2009

In the May 28, 2009 Super Journal report, “TopCal for sodium management during leaching at Mission Viejo Country Club” (756 KB pdf document), a study was conducted to evaluate the ability of TopCal (12% Calcium derived from calcium chloride) to reduce soil salinity levels when it was applied to Poa annua greens prior to leaching. Key conclusions were:

• Leaching of either treated and non-treated greens resulted in significant reductions in soil salinity, chloride and nitrate, but leaching had no impact on soil sodium (parts per million or percentage) on either the treated or non-treated greens.
• Application of TopCal did not result in further reductions in soil salts or sodium, or in an increase in soil calcium in this study. It was simply leaching, whether on the treated or non-treated greens, that provided the only significant reductions in soil salts.
• It is likely that the recommended maximum rate of TopCal (20 gallons per acre) that was applied was not sufficient to provide the desired effects. With pre-treatment calcium levels in the soil at about 1,000 ppm, the additional 13 ppm provided by the TopCal would not be expected to have an appreciable effect on increased calcium levels, or in displacement of sodium. For comparison’s sake, the current standard practice for management of soil sodium relies on multiple applications of gypsum, at a rate of 10 lbs/1000 sq ft. With each gypsum application delivering 50 ppm of calcium, and with monthly applications made (for a total of 600 ppm calcium added to the soil over the course of a year), this strategy has resulted in quantifiable and significant reductions in soil sodium levels under a wide range of conditions. For TopCal to approach this level of performance, the maximum rate would have to be increased almost four-fold, and applications would have be made on a monthly basis.
• A follow-up test that evaluates the impact of gypsum, when used under the same conditions, will be implemented later this year

Bottom line: Leaching, as is well known, is an effective method for reducing soil salts. For further reductions in salts, calcium-based products can be used to displace sodium. Liquid (calcium chloride solution), calcium-based products such as TopCal are much easier to handle than alternatives such as gypsum, but the current labeled rate of application for liquid products is currently too low to generate reductions in soil salts.

Project title: Managing sodium with calcium chloride

Principal investigator: Kevin Hutchins, Mission Viejo Country Club, Mission Viejo, CA

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

Report (756 KB pdf) posted 5/28/09