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Compost tea slowly gaining golf converts
By Andrew Overbeck
Golf Course News
February 2002 |
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With mounting environmental pressures and increasing chemical costs, some superintendents are turning toward sustainable agricultural techniques.
On the forefront of this trend is compost tea, a higher-tech version of a centuries' old technology that "brews" compost to create a concentrated liquid "tea" that delivers beneficial microbes and low levels of nutrients to turfgrass. The brewers, which have been commercially available since 1998, are used most heavily in agriculture settings. While there is no scientific evidence to directly support it, superintendents using compost tea report less disease pressure, less need for fertilization and irrigation and all-around healthier turf.
"Three years ago I was getting dollar spot that was unbelievable," said Charles Clarke, superintendent at Woodbury Country Club in Woodbury, N.J. "I was getting five days of control out of Bayleton and seven days out of Daconil. Two years ago I started spraying with compost tea every seven days and by the end of the summer I saw results. This year I was getting 15 days of control out of Daconil and 31 days of control out of Chipco GT." As a result, Clarke was able to reduce his fungicide budget by 30 percent.
Although Clarke realizes that one year's results are not a true test, he is planning on buying another 100 gallon brewer for next season.
Superintendent Troy Russell at Bandon Dunes Golf Club in Bandon, Ore., has two brewers and irrigates with compost tea every two to three days.
"I have not had to put down a fungicide for two years now," said Russell. "Compost tea is not a panacea, but it is part of our plan to be sustainable." Under a mandate from the owner, Russell is trying to go as natural as possible using organic fertilizer and wetting agents.
David Sayley, superintendent at Rooster Run Golf Club in Petaluma, Calif., has had similar results in his three years of using compost tea.
"I have sprayed three applications of fungicide in that time," he said. "This is not going to solve all disease problems, but if you have healthy turf, you have less disease pressure."
How it works
Brewing proper compost tea begins with high-quality compost that contains a diverse mixture of fungi, bacteria, nematodes and protozoa. Depending on the size of the brewer (they range in capacity from 25 to 500 gallons) the appropriate amount of compost is placed in a perforated basket and then the tank is filled with water and jump-started with an activator mixture. The compost is then aerated for 18 to 20 hours and is immediately ready to be diluted and sprayed onto the course or fed into the irrigation system. It must be used between six and 10 hours of brewing.
While the process behind making compost tea is relatively simple, the scientific theory behind it is rather complicated.
Soil food web
When the bio-rich compost gets aerated in the brewer the amount of microbial activity in the mixture expands exponentially. While there is no doubt that the mixture provides nutrients to the turfgrass, scientists and superintendents alike theorize that microbes are clinging to the leaf surface and keeping diseases from attacking the plant.
"We are looking at how the biology of compost tea suppresses disease," said Elaine Ingham, Ph.D., an associate professor of botany and plant pathology at Oregon State University who is building supporting data for the use of compost tea. "If you get the surfaces of the roots and foliage of plants properly protected by beneficial organisms then diseases are suppressed."
The biological inputs help rebuild what Ingham calls the "soil food web."
"If you get the biology back in there you don't have to use pesticides anymore because you don't have diseases," she said. "You also don't have to use as much fertilizer because it prevents nutrients from washing out of the soil."
Ingham also runs Soilfoodweb, Inc., a commercial consulting firm that analyzes soil samples for farmers. To date, she has consulted with almost 300 golf courses. The firm also publishes a compost tea manual and conducts educational seminars.
Problems catching on
If some superintendents and farmers are having positive results, why isn't compost tea more widely used?
When it comes to golf, clearly more research is needed, said Mike Kenna, director of research for the United States Golf Association's Green Section. "I think these products have a place," he said. "But the thing that concerns me is the lack of university research. How do they know whether the microbial activity or the low levels of nitrogen are providing those results?"
Superintendents already using compost tea agree that more research is necessary.
"The average superintendent is a 'show me' person," said Russell. "It will take scientific evidence before superintendents are going to risk their jobs. In the real world they have to provide good turf conditions on a daily basis and most aren't willing to take that leap of faith."
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