GreenTRX underwent field testing at Penn State University this spring. The trials were initiated at the Joseph E. Valentine Turfgrass Research Center on May 17 and are being supervised by Dr. Max Schlossberg, Associate Professor of Turfgrass Nutrition and Soil Fertility.
We sat down with Dr. Schlossberg to discuss the GreenTRX trials, what was observed during testing, and the benefits of using a slow-release fertilizer product.
When you field test a new product, what are some of the things you're watching for?
Dr. Max Schlossberg: The first thing we do is look at handling characteristics, like dust or odor, and we conduct a rudimentary test on the stability of the granules. Then we take it to the field and apply it at suitable rates, typical of what golf course superintendents would do. We evaluate turfgrass growth, density, and color response over a three to four month period.
What were the turf conditions for the tests?
Schlossberg: We are running this study on a ‘Declaration’ creeping bentgrass fairway. It has better disease resistance than perennial ryegrass and forms a nice tight canopy that most golfers appreciate and have come to expect.
What characteristics give you an idea of how well the product will work under 'live fire'?
Schlossberg: We look at the uniformity of greening to see if there is a mottling effect, something we only do with granular products. Depending on the prill size, or the SGN of the fertilizer, and the rate at which it was applied, we sometimes see an undesirable mottling effect due to sparse distribution of large prills. Ideally we're looking for a uniform release of nutrients or availability in those first two to six days after application.
Were you surprised by any of your observations?
Schlossberg: Yes, GreenTRX provided a rapid greening response, even at low rates. We believe the water solubility or plant-availability of the iron in the product may have contributed to that. It showed an atypically rapid response.
What are the benefits of utilizing a slow-release fertilizer?
Schlossberg: The primary benefit is you can apply greater rates less often. You get what in essence is a controlled availability over a longer replication interval. One of our experimental objectives is to determine the ideal re-application rate and frequency. We applied GreenTRX at rates of 0.25 to 1.25 pounds of nitrogen per thousand square feet and are evaluating reapplication intervals of approximately 45 days.
How safe is the product in terms of risk to the turf?
Schlossberg: Preliminary observations indicate it's safer than fully soluble granules like ammonium sulfate or potassium nitrate at medium to high application rates. The controlled release afforded by GreenTRX’s fraction of insoluble nitrogen makes it safer for the turfgrass. To date we have not observed any canopy burn or desiccation, only prompt assimilation of the provided nutrients.
Rick Woelfel is a Philadelphia-based golf writer and frequent GCI contributor.