Evaluation of Invigorate for Improved Infiltration on Sand Greens
Summary: A study was conducted to evaluate the effect of aerification and application of the soil amendment, Invigorate, on infiltration, turf quality, root mass and length, soil chemistry, and soil gas levels. Key results include:
- Infiltration rate was consistently highest in plots that received a regime of monthly Invigorate treatments PLUS a hollow tine and verti-drain aerification in April, and a small tine aerification in June (treatment 2). In contrast, plots that received only Invigorate applications, but no verti-drain aerification (treatment 4), did not differ significantly from the non-treated check in infiltration rate on any of the dates tested. The positive effects of high infiltration rate were mirrored in the results on root length and soil nutrient levels, but were not correlated with turf quality, root mass or carbon dioxide ratings.
- The improved infiltration rate and increased root length observed in treatment 2 were not mirrored in results obtained for turf quality, root mass or carbon dioxide readings. The highest quality turf was observed for treatment 3, which received a combination of aerification treatments, but was not treated with Invigorate. Similarly, the highest root mass readings were taken from plots that were not treated with Invigorate; root length and root mass were in fact not significantly correlated with one another.
- Soil chemistry results indicate that higher infiltration rates resulted in lower levels of ions such as sodium, magnesium, sulfate, iron, manganese and aluminum. This resulted in lower soil electrical conductivity values, a potential benefit of increased infiltration rates.
- The overall lack of correlation between turf quality and any of the many measurements taken in this study indicates that there is no single tool or measurement that accurately reflects the complex interaction of variables that contribute to turf quality.
- When used in conjunction with aerification, monthly applications of Invigorate resulted in improved infiltration rates. However, aerification - particularly a springtime deep tine aerification - was critical to improved infiltration rates. When the deep tine aerification step was omitted, Invigorate applications did not result in any appreciable benefits. For this reason, Invigorate should be used only in conjunction with aerification, and not as a substitute for it.
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Principal Investigators: Wendy Gelernter, Ph.D. and Larry J. Stowell, Ph.D., CPPP, CPAg
Cooperator: Candice Combs, Balboa Park Golf Course
Sponsor: Milliken
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.
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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.
