Soil
Managing sodium with calcium chloride
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
Changes in soil chemical factors following rainfall and calcium chloride applications
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
Evaluation of leaching tactics
Managing soil salts is a challenge wherever rainfall is limited and infrequent. That is why Patty Reedy and Bruce Williams, CGCS at Los Angeles Country Club have taken time to study leaching tactics to refine the process to a science. In their latest study on LACC's USGA spec, A4 bentgrass greens, they leached test greens for 3.75 hours generated the following results:
- The reduction in salinity was the same (about 20%), whether the drains were left open during leaching or they were closed during the initial period of the leaching event followed by opening the drain once the root zone was saturated.
- When catch cans were used to evaluate the precipitation rates on different areas of the test greens, they found a range between 0.8 in/hr (20 mm/hr) and 2.7 in/hr (69 mm/hr). Although this range is very wide, we have seen similarly wide ranges in precipitation rates in other locations, as shown in a recent study on irrigation distribution and turf disease. This variability is at least partly due to general problems in irrigation design that result in uneven distribution patterns (see the PACE Insights, Issues in irrigation: the uniformity myth (254 KB pdf document).
- The more than three-fold range in precipitation rates had a significant effect on the pre-leaching levels of sodium detected in the soil, with the lowest precipitation areas showing the highest sodium levels, as shown in the graph on the right.
- After leaching, the differences in sodium that were a result of differences in precipitation rate had vanished. In other words, leaching produced the desired effect of not only lowering soil salts in all areas of the green, but of also removing the variability in salt accumulation caused by variable precipitation rates.
Principal investigators: Bruce Williams, CGCS and Patty Reedy, The Los Angeles Country Club, Los Angeles, CA.
The full print version of the report is available at Evaluation of leaching methods on USGA specification greens (611 KB pdf document).
Report posted 11/15/08
