University lab and field tests typically indicate that compost helps improve nutrient levels, water retention and thatch in a wide variety of soils. But, will these claims hold true in real world applications?
After hearing for many years about university compost experiments, two golf course superintendents launched their own research to demonstrate whether the agronomic benefits seen in compost lab tests can be realized on their own courses.
There is evidence that compost helps fight turf grass diseases by creating conditions that support high populations of beneficial microorganisms that may crowd out or directly attack harmful fungus.
Fungal diseases are especially critical in golf courses, because the grass is under severe stress from frequent mowing, golfers' spikes, clubs and golf carts. However, governments are cutting the number of fungicides on the market and are tightening restrictions on frequency and application rates.
Such restrictions are a concern for John Napier, superintendent of the 27-hole Stanley Golf Course in New Britain, Conn., which hosts approximately 75,000 18-hole rounds yearly. Calling the course "a golf factory that gets a lot of stress," Napier, in conjunction with GreenCycle Inc., Northfield, Ill., is building a putting green sod nursery and using compost as a soil amendment in new construction.
Although greens (or nurseries) built with compost don't meet the current putting green specifications of the United States Golf Association's (USGA) Green Section, which requires peat as the organic root-zone element, Napier presented his ideas to Greg Bugbee, a scientist with the Connecticut Agricultural Experiment Station in New Haven.
Not all courses can afford to have USGA-spec greens, and Napier and Bugbee wanted to see if the compost could produce a good green at a reasonable price, since compost, unlike peat, introduces beneficial microbes.
Bugbee drew up an experimental design and helped obtain permission from the state Department of Environmental Protection to allow GreenCycle to use biosolids from the town of Farmington's municipal waste water plant.
The plan is to test three compost styles - yard waste, biosolid and a 50/50 yard-biosolid blend. The composts will be blended at two different rates with sand - 25 percent and 50 percent by volume. There also will be "control" plots that use straight sand and a sand/soil mix. Overall, there will be 13 different root-zone mixes, and each mix will be tried in three separate plots, for a total of 39 test beds. The experiment will run for at least three years.
Seed germination is the initial concern; the plots will be seeded and covered with geotextile covers. Napier has used this seeding method before and is interested in seeing if the compost, in its continuing de-composition, will exude enough heat to excelerate germination of the sown Providence bentgrass.
The new turf's maturation in the different soils and the question of whether composts might produce something harmful to young plants are other top concerns.
Napier also will be scrutinizing what happens in other realms, such as fungal disease attacks, insect infestations and fertilizer and water requirements.
One of the most important issues is the mechanical strength of the root-zone mixtures, Napier says. Adding any organic to sand makes the matrix more compressible and more subject to root-weakening compaction than straight sand. Soft-root mixes demand more frequent aeration and maintenance. However, softer soils may lead to a more dense root mass, which leads to greater compaction resistance.
While Napier focuses on his fledgling greens, in the Chicago suburb of Glenview, Ill., superintendent Dan Dinelli set his compost sights on the fairways. His course is maintaining fairway test plots for a disease-suppression study started last spring by Michael Cole, a professor at the University of Illinois at Urbana-Champaign.
Dinelli also is using compost as a staple in his fairway top-dressing program and is researching the machinery and techniques that will facilitate the use of compost in place of peat during those maintenance operations.
The crews made one compost application on fairways, sparing some test patches for later use as comparison. "The compost reduced the thatch and increased the earthworm activity, judging from the concentration of the surface castings," he says. "[It] gave us a denser, greener stand of turf."
Disease suppression on the compost-treated fairways, however, was hard to gauge, says Dinelli. Disease pressure varies yearly, and 1996 had the kind of mild weather that usually reduces fungal infestations.
Also affecting the test's results is the fact that Dinelli's crews spread the compost one time. "I don't think you can fairly evaluate a product you apply once during the growing season," he says. "I'd like to do the compost once a month and see what happens over the long term."
But, given those qualifications, Dinelli says the course required just 38 percent of its typical fungicide expenditure.