Vermicomposting in the U.S.
Vermicomposting, the process of producing compost with earthworms, began in the United States in the 1940s. It started in the household with kitchen wastes being processed with the “red wiggler” (Eisenia fetida). The first use of the term “vermicomposting” (coined from vermis, Latin word for worm, and compost, decomposed organic matter) was in 1980 at the First Applied Workshop on the Role of Earthworms in the Stabilization of Organic Residues held at Kalamazoo, Michigan.
Since then, the science and technology of vermiculture (earthworm raising) and vermicomposting have advanced. Of note are the pioneering work of Roy Hartenstein and his co-workers on the use of earthworms for the stabilization of sewage sludge in Syracuse, New York and the studies of Clive Edwards on the role of earthworms in soil ecology in the Rothamstead Experimental Station in England.
This writer was invited by Dr. Clive Edwards, professor and head of the Soil Ecology Laboratory of the Ohio State University to visit commercial vermicomposting farms and exchange experiences with researchers in the U.S. My visit was sponsored by a collaborative project supported by the U.S. Department of Agriculture.
There are various methods of vermicomposting applied in the U.S. In the household level, the use of bins or containers is common for processing of kitchen and yard wastes. For commercial production of vermicompost, outdoor windrows and indoor manual or mechanized continuous-flow reactors are used. The windrow system is practiced by 90% of the producers. California is said to have the largest vermicompost production in the country.
We visited the Easy Crawler Worm Farm of Jeffrey Easley in Dunnigan, California. The farm has 20 windrows in its 1.6-hectare facility. Each windrow (a row of compost pile) measures about 25 meters long, 1 meter wide and 0.3 meter high. The space between windrows is three meters.
It takes 50 tons of cattle manure to fill the windrows in the Easley farm. With a density of 3 to 5 kilos of E. fetida per square meter, about six months are needed to complete one cycle for the production of 1.5 tons of vermicompost per windrow.
With mechanization, the farm is operated only by Jeffrey and his wife. He makes a net of $60 (P3,300) per ton of vermicompost which is sold at $300 (P16,500). The farm also sells live earthworms at $7 per pound (P847 per kilo).
Another facility in California we visited was the Sonoma Valley Worm Farm owned and operated by Capt. Jack Chambers (he is also a commercial pilot). It has three mechanized vermicomposting reactors, each measuring 27×1.3×1 meter with a capacity of 51 cubic meters of pre-composted cattle manure.
Each reactor costing $15,000 (P825,000) is stocked with 500 kilos of worms with an initial 30-centimeter depth of the feedstock. Then as the worms eat their way up to the top 15-centimeter layer after a week, a 15-centimeter layer of fresh feedstock (pre= composted manure) is added per week in each reactor until the full capacity is reached.
A moving horizontal bar at the bottom of the reactor allows the vermicompost to fall through the 5-centimeter meshed bottom of the elevated bin to the floor where it can be collected without disturbing the worms. With such a continuous-flow system, about four cubic meters of vermicompost are harvested weekly from the three reactors.
The Chambers farm produces 152 cubic meters of vermicompost a year which is sold at $395 (P21,725) per cubic meter. It also produces “vermin tea” with a machine that costs around $1,300 (P71,500) with a mixture of 1 kilo of vermicompost in 100 liters of water. The machine provides aeration for the “brewing” and comes out with the filtrate in 24 hours.
Capt. Jack uses “vermin tea” for foliar application on his grapes with a power sprayer every two weeks for suppressing the fungal disease known as powdery mildew.
We also visited the vermicomposting facility of the Oregon Soil Corp. in Portland, Oregon operated by Dan Holcombe. The company processes the food wastes coming from a major producer of agricultural products (fruits and vegetables) using a mechanical reactor with dimensions of 27 x 2.5 x 0.45 meter. The unit which costs about $60,000 (P3.3 million) has a capacity for vermicomposting 36 cubic meters of food wastes with around 800 kilos of worms.
Holcombe’s reactor which is an adaptation of the design developed by Dr. Edwards in the 1980s produces 2.28 cubic meters of vermicompost a day. With a recovery rate of 70% from the wastes, the product having a moisture content of 30% is sold at $140 (P7,700) per ton.
The market for vermicompost in the U.S. is the increasing demand for organic crops and plants produced from farms and gardens without the use of chemical fertilizers and pesticides.
Dr. Edwards, who is considered the world’s authority on vermicomposting and the use of earthworms in organic waste management, says, “Compared to ordinary compost, vermicompost is much more preferable for use as plant growth media.”
Another vermicompost advocate, Larry Martin, the head of Vermitechnology Unlimited based on Orange Lake, Florida said: “The money is in the castings. With the demand for organic products, we can sell everything we produce.”
Vermicompost has been proven by many studies to be an efficient and cost-effective soil amendment for improving fertility, enhancing microbial diversity and promoting plant growth. In recent studies conducted by Dr. Norman Arancon, a post-doctoral researcher, and his colleagues at Ohio State University, it was found that vermicompost effectively reduces insect infestation of pepper, tomato and cabbage in the greenhouse, and parasitic nematodes of strawberry and grape in the field.
Good news for local vermicomposting practitioners. Drs. Clive Edwards and Norman Arancon (a Filipino from Bukidnon) will be the main speakers and resource persons, among others, of the First International Symposium-Workshop on Vermi Technologies for Developing Countries to be held in Los Banos, Laguna on November 16-18, 2005. Interested parties may contact the PCAMRD Vermi Action Center through telefax (049-536-1582) or e-mail (firstname.lastname@example.org).