8/9/2022 - By Dr. Raymond Snyder

Study: Using Sulfur to Reduce Soil pH in Established Turfgrass

Location: Bear Lakes Country Club in West Palm Beach

Collaborator: George Snyder, Ph.D.

Date: May 26, 2022

Agricultural sulfur (S) is used for reducing soil pH. However, numerous authorities have cautioned against using it in established turfgrass because turfgrass may be damaged. Rieke (1970) reported injury and loss of bentgrass turf from an application of 60 pounds S per 1000 sq ft. Maximum rates of only ½ pound per 1000 sq ft have been recommended on putting greens (McCarty, 2001), and this author and others (Beard, 2002; Shaddox and Sartain, 2008) have suggested application rates of 10 pounds or less per 1000 sq ft for other established turfgrass. Reicher (2022) has stated that S is ineffective for reducing the pH of turfed soils because of the low rates that must be used.

Methods and Materials

An unreplicated exploratory sulfur-rate study was conducted at the Bear Lakes Country Club in West Palm Beach. On May 26, 2022, S rates of 0, 5, 10, 15, and 20 were applied on a Tifeagle bermudagrass green, and on a Celebration bermudagrass tee. Based on 0–2-inch soil samples, both appeared to be constructed with sand, meeting USGA specifications for putting green mixes (USGA, 1993). The green contained 2.1% (by weight) organic matter, and the tee contained 4.6%. The plots were a one-foot diameter circle, except for the 0 rate, which was an untreated area immediately adjacent to the circular plots. A granular 90% S source was used (Tiger 90CR. Tiger Sul Products LLC. Shelton, CN).

The product application rates were 1.98, 3.96, 5.94, and 7.91 g per plot for the 5-, 10-, 15-, and 20-pounds S per 1000 sq ft treatments, respectively. Mowing and irrigation were conducted by the golf course according to their schedules. Between the second and third week after application, the green was core aerified and top-dressed. Some S may have been displaced from the plots by these operations. However, after the first-week observation, considerable rainfall occurred on June 4^th (4.6 inches at nearby Palm Beach International Airport), which should have dispersed the S granules and moved them into the turfgrass cover.

Plots were examined and photographed weekly. In the fourth week, 15, 2-inch deep by ¾-inch diameter soil samples were extracted and analyzed for pH and S extracted with pH 4.8 ammonium acetate.

Results and Discussion

No grass discoloration or damage was observed in any of the plots on any of the observation dates (attached photographs). Soil pH was reduced from 7.0 to 6.3 on the green, and from 6.6 to 5.3 on the tee at the highest S application rates (Table 1).

Conclusion:

Sulfur application rates up to 20 pounds per 1000 sq ft did not damage bermudagrass turf on a green or a tee, but pH was substantially reduced.

Table 1. Soil pH and extractable soil S four weeks after sulfur applications.

Literature Cited

Beard, J. B. 2002. p. 157 In Turf Management for Golf Courses, 2^nd Ed. Ann Arbor Press, Chelsea, MI.

McCarty, L. B. 2001. p. 92-93 In Best Golf Course Management Practices. Prentice Hall, Upper Saddle River, NJ.

Reicher, Z. 2022. Sulfur is not effective for lowering the pH of turfed soils. https://turf.purdue.edu/sulfur-is-not-effective-for-lowering-ph-of-turfed-soils/

Rieke, P. E. 1970. Soil pH for turfgrasses. p. 212-220 In Proc. 1^st Int. Turfgrass Res. Conf, Harrogate, England.

Shaddox, T. W., and J. B. Sartain. 2008. Soil Testing and Interpretation for Florida Turfgrass. https://edis.ifas.ufl.edu/pdf/SS/SS31700.pdf

USGA Green Section Record, March/April 1993