Biomass Reduction Agents on Surface Organic Matter and Thatch Content
Evaluation of Biomass Reduction Agents on Surface Organic Matter and Thatch Content in Golf Course Putting Greens R.E. Gaussoin and T.A. McClellan
Organic matter accumulation in the upper 5 cm of the root-zone is a primary reason why putting greens lose the capacity to take water. Organic matter accumulation and thatch formation result from both living and nonliving plant material and soil micro-organisms located near the putting green surface. Too much thatch can be detrimental to turf health and decrease chemical and fertilizer efficiency. Therefore, turf managers are continually monitoring and making efforts to limit thatch development. Sand topdressing is most commonly used to reduce thatch, but this cultural practice can be difficult to perform because it is time consuming, labor intensive and interferes with golfing play. A research experiment was conducted in 2004 at the John Seaton Anderson Turf and Ornamental Research Center near Mead, NE to evaluate products to facilitate breakdown of surface organic matter.
The study was conducted on USGA specification putting greens located at the John Seaton Anderson Turfgrass Research Facility in Mead, NE. The greens were constructed in 1997 with 80% sand and 20% peat (by volume) and seeded with Providence creeping bentgrass. Greens are mowed daily at 0.305 cm (0.12 inch) and irrigated at 80% ET. Annual fertilizer rates are as follows: 6 lbs N, 4 lbs P, and 6 lbs K / 1000 sq. ft.
Three blocks of 4 plots each (individual plots measure 3’x 3’ in size) were designated on July 27, 2004. Each block contains 3 treatments and a control (untreated) that were randomly applied and replicated 3 times (blocks). Treatments and application rates are as follows:
1) untreated (control)
2) GRIGG™ Carboplex® (15 fl.oz./1000 ft2)
3) GRIGG Bio-Blend™ (6 fl.oz./1000 ft2)
4) GRIGG Carboplex / Bio-Blend (9 and 3 fl.oz./1000 ft2)
Both products are fertilizers (analyses of Bio-Blend and Carboplex are 10N-0P-0K +5Ca and 6N-4P-4K, respectively) and theoretically serve as food sources to micro-organisms in the soil. As a result, microbial activity is presumed to increase and organic matter is broken down more rapidly and effectively.
Applications were made using a backpack sprayer and lightly watered in immediately to move products into the root-zone. Treatment schedule included applications every 2 weeks (beginning July 27th, 2004) and concluded on October 6, 2004 for a total of 6 applications. On October 13, 2004, one week following the sixth and final application, soil samples were collected using a soil probe. Green vegetation and thatch were removed (combined depth was approximately 1/8” to 1/4"). Ten samples were taken per plot with 6 cut at the 2” depth and 4 cut at the 4” depth. Thatch was determined visually by noting its depth, and organic matter was determined by the “loss on ignition” method. This is accomplished by placing soil samples in an oven at 105C for 24 hours and then in a muffle furnace at 440C for 12 hours. The muffle furnace essentially removes organic matter from the soil and percent organic matter can then be determined by comparing the muffle furnace sample weight to the oven-dried weight.
Visually, there were no differences among the treatments and control. In the upper 2” of the root-zone, treatments 3 and 4 contained less organic matter than the control while treatment 2 was higher than the control. Statistically, however, the differences were not significant (see Table 1). In the upper 4” of the root-zone, treatments 2, 3 and 4 were all lower than the control. Statistically, however, the differences were not significant (see Table 1). Treatment 3 was lowest at both depths; treatment 4 was the next lowest at both depths (see Table 1). Bio-Blend reduced organic matter by approximately 5-6% at both depths. Carboplex/Bio-Blend reduced organic matter by approximately 4-5% at both depths. Treatment means for organic matter (%) are as follows:
Table 1. Percent organic matter for treatments at two depths. Treatment means with the same letter are not significantly different (P<0.05).
While nearly all treatments contained less organic matter than the control at both the upper 2” and upper 4” depths, the differences were not statistically different. Bio-Blend appears to be more effective than Carboplex as treatment means were lowest for Bio-Blend and next lowest for Bio-Blend/Carboplex. Treatments 1 (Control) and 2 (Carboplex) were both higher than either of the treatments containing Bio-Blend. The duration of this study was 13 weeks, and since a slight trend was noticeable in reducing organic matter, it is possible that continuing the treatments for a longer period of time may result in increased effectiveness for organic matter reduction.
Should further research show significant reduction in biomass in the surface of putting green root-zones, superintendents and turf managers might have a more affordable, less time consuming, and more golfer friendly alternative to sand topdressing as a means to control thatch development. This will obviously not replace sand topdressing as a required cultural practice, however, but it may improve the arsenal in which superintendents can use in the fight against thatch and organic matter accumulation.