RESEARCH UPDATE: ORGANICS TAKING ROOT
Researchers are exploring the value of organic-based strategies in turf establishment and finding positive results.
In one study, a University of Missouri researcher, cooperating with a USDA Agricultural Research Service microbiologist, found that bentgrass established in a sand root zone amended with an organic mixture suffered much lower rates of dollar spot infection than bentgrass established in a 90:10 sand/peat mix more typical of golf greens.
The organic amendment the researchers used was bokashi, the Japanese term for this mixture of horse manure, brewery waste, wheat bran and charcoal. Also included in bokashi is a diverse culture of aerobic and anaerobic microorganisms termed EM, for “effective microorganisms,” by a Japanese researcher.
Though disease-suppressing soil microbes are not well-understood, the researchers hope that their study will help spur additional exploration of the topic. Understanding EM benefits for turf establishment and maintenance could open the door to a vast, underutilized resource.
In another study, two Ohio State University researchers looked at the effects of incorporating composted biosolids into the poor soils typical of many new residential landscapes.
The investigators used two products — ComTil and TechnaGro — both derived from composted sewage sludge and mixed with wood products. These were tilled into structureless, nutrient-poor subsoil, which was then planted with Kentucky bluegrass, perennial ryegrass or a mix of both. Similar plots were planted without the incorporated compost for comparison.
The results clearly showed that turf established more quickly in the compost-amended soil. In addition, leaf rust — a common disease of newly established turf — was much reduced in the amended ryegrass plots. The researchers concede that the disease reduction was probably due to increased nitrogen levels, as was the quicker establishment. However, other studies have discovered compost-induced disease resistance in other crops, so it's possible that this could've been a factor as well. Regardless of the cause, this is the first documented evidence of soil-incorporated composted biosolids suppressing foliar turf disease.
Both of these studies show that incorporation of organic materials can benefit turf in a variety of ways. Greater utilization of the materials used in this research as compost could also help solve disposal problems faced by most cities.
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