PACE Turf - Turfgrass Information Center

Soil Compaction: A Case Study at Candlewood Country Club

Summary: One method of measuring soil compaction, or strength, entails recording the pressure needed to force a rod (cone tip penetrometer) into a soil.  If the soil provides resistance of more than 300-400 psi, plant roots have difficulty or are unable to penetrate the soil. For this reason, plant roots are frequently found only in the top 2 3” of soil, where compaction is usually less than 300 psi. In this study, readings taken inside the sand-filled vertidrain holes, one day after vertidrain treatment showed that the vertidrain reduced compaction at depths of 3 - 5” from about 500 psi to less than 400 psi (Figure 1).  Five weeks later, we went back to evaluate compaction again, but it was difficult to identify vertidrain holes.  For this reason, the readings we obtained (Figure 2) were probably taken from areas between holes. As expected, readings remained unchanged at 500 psi at depths of 3 - 5”.  It is likely, however, that the compaction level in the vertidrain holes remained below 400 psi.  The common observation of deep roots in vertidrain holes supports this hypothesis. An additional advantage of vertidraining may be improved water infiltration. Even though compaction was not relieved in general throughout the green, the greens take water well in the summer indicating that water infiltration is one of the greatest benefits of this method.

Printable version of full report

Principal Investigator:  Larry Stowell, Ph.D., CPAg

Cooperator:  Mike Caranci, Candlewood Country Club

Sponsor:  PACE Turfgrass Research Institute

Warm Fall 2003 Impacts Overseed in Southwest

The moans and groans started when September average air temperatures stayed stuck above 90F (with maximum temperatures hovering over 100F), and escalated to sobbing, kicking and screaming when they stayed high (rarely dipping below an average of 80F) through the first three weeks of October.  In short, all of the elements for a difficult overseed were in place during the Fall of 2003.  For while the objective of overseeding is to encourage the growth of cool-season turf types such as ryegrass and Poa trivialis, and to discourage the growth of bermudagrass, the weather this autumn conspired to create exactly the opposite effect.  The above-average weather this fall has been absolutely ideal for bermudagrass, which flourishes when air temperatures are between 75 and 100F.  These same warm temperatures have weakened the growth of ryegrass and Poa trivialis, both of which prefer lower air temperatures between 60 and 75F. When average temperatures climb to above 80F, ryegrass and Poa trivialis take a big dive. The survival of these cool-season turf types is further compromised by the fact that bermudagrass growth escalates rapidly at these temperatures, crowding out the weaker rye and Poa triv stands.

Letter describing the problem

PACE Clubhouse Edition prepared for HiLo GCSAA

Effect of Primer Applications on Nutrient Leaching in Turfgrass Greens

Summary: A replicated experiment was designed to evaluate the effect of Primer on the leaching of nutrients on a Poa annua golf course green. Following six monthly applications of Primer at 6 oz/1000 square feet, analyses conducted on soil samples from 1, 2 and 4 inches depths revealed no significant differences between treated and untreated plots in levels of over 20 nutrients including, sodium, magnesium, calcium, total salts, and even the highly leachable potassium. In addition, no phytotoxicity and no effects on turf quality were observed in areas treated with Primer. On the basis of these results, multiple applications of Primer to turfgrass do not increase leaching of nutrients in the soil.

Full print version of report (123 KB)

Investigators: Wendy Gelernter, Ph.D. and Larry J. Stowell, Ph.D., CPPP, CPAg

Cooperator: Mark Schaer, San Luis Rey Downs

Sponsor: Stan Kostka, Aquatrols

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