Articles

---

Compost tea is defined as a liquid extract of compost, containing the nutrients, microorganisms and organic matter that are soluble or able to be held in suspension. The process of extraction varies with the type of equipment used to make the tea, but the essential components are the same: start with high quality compost, water, a food source for the microorganisms, and provide ample aeration throughout the 24-hour extraction period. Consistency is important in all of these components—although it may not always be easy to achieve. Finding a source of consistently good compost can be a challenge for growers in some areas. Hope is on the way, however. Richard Eaton has now relocated to Hawi from Maui and has good quality compost available for making tea.

Compost tea equipment types range from numerous homemade versions for small-scale operations to a handful of industrial-grade, commercial-scale systems for larger operations. For large operations, consistency in the equipment is as critical as the quality and consistency of the compost. Given a source of good compost and reliable extraction equipment, a producer should be able to consistently produce good compost tea.

Knowing how and when to apply the tea is also important to the success of an organic production strategy that includes compost tea. The ideal number, rate and timing of applications, as well as the mode of application, varies with crop, soil type, weather and disease conditions.

Compost tea is primarily known for its ability to boost soil biological activity by adding millions of bacteria, fungi, actinomycetes, protozoa and nematodes. A diverse representation of these organisms in large numbers is essential to healthy soil and plant interactions. A deficiency of soil biological activity or a critical imbalance in species diversity is a precursor to other deficiencies leading to crop disease or malnutrition.

There are a number of HOFA growers that have been using compost tea for some time, some of whom are highlighted below.

Maui Pineapple has been using compost tea for over a year and a half in its organic production. Over the last 6 months, Organic Farm Manager Scott Meidell has been conducting a trial to evaluate the effects of compost tea. The trial consists of two roughly identical half-acre plots—one control plot and one treatment plot. Each plot contains about 12,000 plants. The control plot receives the plantation's standard organic fertilizer "cocktail" at regular intervals. The treatment plot receives the same "cocktail" as the control plot, except that in lieu of one of the scheduled applications, compost tea is applied at the rate of 20 gallons per acre. All treatments are foliar spray applications. Evaluation includes leaf sample analysis (leaf color, tissue K, P and Mg) and plant weights throughout the growth cycle of the crop. The first set of data is expected at the end of this month, at 6 months' growth. Meidell expects any significant differences between control and treatment to begin to occur somewhere between 8 and 12 month, so stay tuned. Compost tea for the trial is produced in Maui Pineapple's 100-gallon system from Growing Solutions, Inc., using vermicompost made on-site and Growing Solutions' Compost Tea Catalyst.

Ono Farms, also on Maui, has been using compost tea for over 3 years on papaya, bananas, avocados and other exotic fruits. Lilly Boerner of Ono Farms first noticed the effects of compost tea applications in her orchards visually. She was able to see a difference in color and plant vigor between treated and untreated areas of the orchard almost immediately. She attributes the effects to the abundance of life introduced by the compost tea into the soil and plant ecosystem. Boerner has observed that there is more fruit, greener leaves, and an apparent reduction in disease incidence since they began using compost tea. Phytophthora, a persistent problem for papaya, has been kept at bay in Ono Farms’ orchards. The Boerners initially sprayed their orchards twice a week with compost tea. They are now applying it less often, but usually at least once a month. When a particular problem or disease is observed, the area is immediately treated with compost tea. Their approach to application is to get thorough coverage with a fine mist over the entire plant surface, including the underside of the leaves. The Boerners make their own compost from mostly on-farm sources, and formulate their own microbial foods from a variety of ingredients. They no longer add molasses or sugar into the batch when they make compost tea, and they save a little bit from each batch as a starter for the next. “It’s all about the health of the soil,” says Boerner.

Hugh Johnson at Puna Organics is into his second full year of using compost tea on his organic yellow ginger. As a “gypsy farmer” who deals with short-term leases for his crop production, Johnson rarely has the luxury of time on his hands for building the soil. His strategy is to use compost tea as a concentrated source of beneficial microbes to accelerate soil biological activity in order to maximize the impact of the organic fertilizers that he applies to his crop, potentially reducing the amount of fertilizer that is required. Although he has not conducted formal trials, Johnson has observed that his crop is healthier and better able to resist diseases with the use of compost tea. His advice to potential compost tea users is to focus on finding a source of good compost. He uses a couple of different sources of compost and vermicompost. “Compost tea is only as good as the compost”, says Johnson, “and the proper application equipment and timing is also critical.”

Kauai Organics, Tropica, Landscape Hawaii, and many other companies are now using compost tea as a regular part of their nutrition and disease prevention programs.

And the Puna District now has its very own compost tea expert…. HOFA’s Kelly Lange just received her 25-gallon GSI system to use at her Kapoho Farm!!  

For more resources on the use of compost tea, contact Growing Solutions, Inc. at 888-600-9558 or www.growingsolutions.com