Compost teas can relieve stress on turf and you

A superintendent I do soil testing for said at a recent presentation that the year before he began integrating compost tea into his program he spent $35,000 per 9 holes to control one disease, dollar spot. This obviously wasn't the only disease he had to control. With diseases becoming resistant to existing fungicides and always having to look for materials that perform well, it's hard to keep your piece of mind, and it's hard always having your job on the line hoping these materials will work.

Six years ago this superintendent did some soil testing and learned the biology in his soil was lacking the diversity of beneficial organisms needed to grow healthy turf with a better disease resistance, and the ability to build soil structure and retain and cycle plant nutrients. A compost tea program was adopted to help improve the soil health.

There are many factors that can damage the beneficial microbes in our soils. Heavy foot and cart traffic particularly on greens and tees are a factor that is beyond our control. Low organic matter, poor soil structure, applications of pesticides, and inorganic fertilizers are all factors that will have a negative impact on beneficial soil biology. Integrating compost tea into the spray program can help reduce these negative affects.

Compost tea is by no means a silver bullet or a miracle drug, but can have a significant impact on many levels. First of all it is very inexpensive to apply tea. It can be brewed for about 30-50/cents per gallon. With application rates in sprays that replace fungicides and fertilizer typically 10-20 gallons per acre. You do the math. How does that stack up with your current fertilizer of fungicide sprays? OK, but how effective is compost tea at maintaining fertility and helping control disease? Most golf courses that have given it a real go have reduced inorganic fertilizer apps at least 50% to as much as 90%, and ditto for the fungicides. Typically, some organic fertilizers would be used as an additive to the teas.

THE PRESIDIO

The Presidio Golf Course in San Francisco did some compost tea research in 2000/2001 that yielded very good results in control of Microdochium Patch, some positive but not spectacular results with Anthracnose, and an excellent increase in rooting depth. The compost tea technology has exploded since then, and there are many courses having good results currently.

So exactly what is tea and how does it work? Compost tea is a highly aerobic solution of the following: Soluble nutrients found in compost; beneficial microbes found in compost; foods to grow and multiply these beneficial organisms (organic fertilizer type materials); and water.

These four components are "brewed" for 12-24 hours, usually. During this brewing process the beneficial microbes grow and reproduce exponentially due to the presence of abundant food resources and oxygen. With the correct brewer and foods, the amount of bacteria in the tea can double about every half-hour. Essentially, tea is a way to get the benefits of compost in an easy-to-apply, low-cost liquid.

When it comes to pest/disease control there are many ways compost tea will help. The beneficial bacteria and fungi in the tea out-compete disease organisms for foods and surface area on plants on which to grow. Many beneficial microbes provided in the tea create inhibitory compounds and antibiotics that are antagonistic toward disease. Foods in the tea feed beneficial organisms existing on the surface of leaves, stems, and roots. Fungal-feeding nematodes can feed directly on disease causing fungi in the soil. Predatory nematodes feed on other nematodes including root-feeding nematodes. Entomopathogenic nematodes, bacteria, and fungi can be added to the teas to control certain insects. Things like Bt, Milky Spore, Bauvaria bassina and others are examples.

Bacteria and fungi break down organic matter and retain the nutrients that were present in the organic matter. Protozoa and nematodes feed on bacteria, fungi, and other nematodes and cycle the nutrients being retained into plant available form. This is how the tea improves soil fertility. Also, many elements that have been applied over the years will get tied up in the soil for reasons such as incorrect pH. The microbes will actually adjust the pH as they grow and make nutrients plant available.

Additionally, mycorrhizal fungi that may be sitting dormant in the soil are much more prone to colonize the roots of plants that are not being fertilized with inorganic materials. On one golf course we recorded an average of 200% increase in mycorrhizal colonization per hole within 6 months of starting the tea program. The most amazing part is that no spores were applied; the resident populations were increasing on their own as the soil condition improved.

Good soil biology provides the building blocks of good soil structure. Bacteria stick themselves to organic matter and soil particles making the micro-aggregates. Fungal hyphae wrap themselves around the smaller aggregates to form the larger aggregates. Protozoa and nematodes are highly mobile and maintain good structure as they plow through the soil looking for prey. Teas applied directly into aeration holes have proven effective here.

Weekly tea applications are the most common program. With most compost tea brewing systems if you can cut out four fungicides you have paid for the program, including the materials. The exact rates and recipes are typically prescribed based on the current soil condition and history. Soil testing is good idea for the successful development of the custom tea program for your course. Superintendents tell me that they have much more time to react to disease and other situations because the turf is under much less stress and natural plant defenses are higher. Problems are also not as severe because of all the checks and balances the tea provides. The microbes stay out and work 24/7 so you don't have to.

Paul Wagner is the New York rep for Corvallis, OR-based Soil Foodweb Inc., www.soilfoodweb.com.

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