Revisiting set

A year ago Aquatrols unveiled its Seed Enhancement Technology (SET), an innovative surfactant seed coating aimed at increasing seed germination rates and improving stand establishment for water challenged golf courses.

Promising early trials had Aquatrols representatives excited when GCI spoke with them last year. This month we caught up with Aquatrols’ Dr. Stan Kostka and Field Development Manager Mica McMillan to see what advancements have been made with SET since our last discussion.

A quick refresher for those who may not be familiar with SET: Matt Madsen first developed the idea of using seed as a carrier for soil surfactants while researching strategies to improve rangeland restoration at Utah State University. Familiar with Aquatrols and its history in water management, he reached out to Kostka and the two worked to take Madsen’s idea from concept to reality. Trials were established and the early results proved both promising and surprising.

Since last year, SET trials have spread across the globe with some of the most respected names in the industry examining the technology firsthand. University cooperators in the United States include John Cisar, University of Florida (retired), Bernd Leinauer, New Mexico State University; Mike Fidanza, Penn State University, and Dara Park, Clemson University. Ruth Mann is conducting additional research at the prestigious Sports Turf Research Institute in the United Kingdom.
 

What’s new?

While the early trials were promising, they involved loading rates ranging from 20 to 100 percent surfactant to seed, meaning up to one gram of surfactant was being applied for every gram of seed. While these high loading rates were valuable in determining the initial viability of the technology, they would likely be too cost prohibitive for widespread applications in the real world.

Over the past year, researchers have discovered that a much more cost-effective 6 to 10 percent loading rate performs optimally for most turfgrass species. At this lower loading rate, researchers are seeing better stand establishment, deeper root zone wetting fronts and longer shelf life characteristics.

One of the most exciting test results in the past year came out of a trial in Riverside, Calif. Researchers there seeded SET-treated seeds at half the rate of untreated seeds and watered plots with high salinity irrigation water. At the end of the trial, turfgrass cover was nearly the same for the SET treated Bermudagrass and Seashore Paspalum plots compared to the untreated control (76 percent and 67 percent cover, respectively).

In addition, viability studies have signaled a much longer shelf life for the seed coatings than initially anticipated. Testing at the Sports Turf Research Institute showed promising shelf life characteristics for perennial ryegrass and tall fescue after eight months, according to Ruth Mann. Separate, ongoing shelf-life studies at Aquatrols headquarters show the viability of treated seed is unaffected after 18 months. These results indicate that treated seed may survive in the bag for two growing seasons or more.

Field trials have shown that wetting fronts are moving much lower in the soil than previously observed with SET. In one trial, average water penetration for untreated seed was 50 to 60 millimeters. Moisture moved as low as 200 millimeters – the entire depth of their measurement – with SET seed, according to McMillan. And, more impressively, this improved root zone wetting occurred for many months after initial seeding.

“The improved root zone wetting resumes after initial dry down. This means that there is an increased reservoir of water for anything growing on the surface,” she says.
 

SET and drought

The largest benefit for SET may come in areas facing drought conditions and/or water use restrictions. According to a report from the STRI, “Aquatrols SET improved seedling germination and establishment under water deficit conditions” for Chewings fescue growing in greenhouse conditions.

Back in the states, Leinauer has been looking at establishing seed under severe deficit irrigation conditions, watering to only 50 percent of evapotranspiration (ET) replacement. Greenhouse tests are also looking at establishment under high-heat conditions. McMillan reports that coated seed had a much better stand and less wilt even as temperatures routinely reached 120 degrees in one study.

“Under drought or reduced water conditions, the SET seed really shines,” says Kostka. McMillan adds,” We have shown that we can still get a stand with 50 percent ET replacement. That is phenomenal. The impacts on drought affected areas could be huge.”

If a superintendent is dealing with drought and needs to seed certain areas of his or her golf course, SET coated seed may be a big help. Less seed and less water will be needed to establish a stand and better ground cover will still be achieved. And the soil texture doesn’t seem to make a difference. Better results with SET seed have been observed in silt loam, sandy and water repellent (hydrophobic) soils.

For seeding any time of the year, even during optimal seeding conditions, it may be worth comparing the cost of coated seed to uncoated seed to determine if the savings from lower seeding rates and reduced watering make up for the cost of the SET.

So what’s next? According to McMillan, Aquatrols is looking at how SET may mitigate the negative effects of poor irrigation water quality. Further research will determine the best seed varieties, loading and seeding rates for stand establishment in high salinity conditions.