BioCycle August 2005, Vol. 46, No. 8, p. 60
Research trials at Central Luzon State University and field experiments on farms show increased yields from applications of vermicompost.
Rafael D. Guerrero III

BECAUSE of the tropical climate, abundance of agricultural residues and relatively low-cost labor, vermicomposting is rated an appropriate composting technology for the Philippines. There are more than 10,000 backyard and commercial producers of vermicompost in the Philippines today. Outdoor beds are commonly used for composting units with animal manures, crop residues and other wastes utilized for bedding materials and feedstock of earthworms.
Beginning in the late 1970s, vermicomposting experiments were conducted by researchers of the Central Luzon State University in Muñoz, Nueva Ecija. The earthworm species first used was the “Indian blue” (Perionyx excavatus) native to the Philippines. The mix of materials approximates a C:N ratio of 25-30. A moisture content of 60-80 percent is maintained in the beds that are stocked at 1-2 kg/m2 of earthworms with 100-200 kg/m2 of the substrate. Harvesting of the vermicompost and earthworms is done manually or mechanically after 30 to 60 days of culture.
Vermicompost produced from Murrah buffalo manure, leaves of “ipil-ipil” (Leucaena leucocephala) and sawdust at proportions of 1:1:1 by weight was tested on radish (Raphanus sativus), onion (Allium cepa) and “pechay” (Brassica napus) in a pot experiment. Results showed that with various levels of vermicompost (VC) at 0, 25, 50, 75 and 100 percent, yields of radish and onion were 1.8 and 1.3 times, respectively, more than that of the control (0 percent VC). The yield of “pechay” with 75 percent VC and 25 percent soil was 4.5 times more than that of the control.
With Murrah buffalo manure (66 percent by weight) and dried “ipil-ipil” leaves (33% by weight), P. excavatus juveniles weighing 0.5 gram on the average stocked at 110 per kilogram of substrate yielded one kilogram per 18 kilograms of substrate after two months of culture.
The African nightcrawler (Eudrilus eugeniae) was introduced in the Philippines by Dr. Otto Graff of Germany in 1982. This species eventually replaced the “Indian blue” for vermicomposting because of its more efficient characteristics and lesser tendency to migrate compared to the latter.
In a pot experiment using E. eugeniae- produced vermicompost from 75 percent pig manure and 75 percent sawdust, the weights of cabbage (Capitata oleracea) were significantly more with 50-100 percent levels of VC compared to that with 25 percent VC and were comparable with that using chemical fertilizer at the recommended rate.
INCREASED YIELDS
In a field experiment with corn (Zea mays), the application of vermicompost at 5 tons/ha increased the ear length of plants by 114 percent and total yield was comparable to that of plants fertilized at the recommended rate of inorganic fertilizer.
The use of 2 tons/ha of vermicompost (75 percent grass and 25 percent leaves of Gliricidia sepium) plus 50 percent of the usual chemical fertilizer of sugarcane in two hectares increased the yield by 2.6 times compared to the usual yield using 100 percent chemical fertilizer. It was also observed that the canes were taller and the leaves were greener and more luxuriant with vermicompost.
The plant nutrient content of vermicompost (75 percent grass and 25 percent leaves of G. sepium) was 5.8 times higher on the average than that of the parallel compost (not processed by earthworms). The nutrient quality of the vermicompost was found to be directly related to the kind of bedding or feedstock materials used. The nutrient content of vermicompost, however, decreased with increase in earthworm production.
The Center for Rural Technology Development (CRTD), a nongovernment organization, in Calauan, Laguna which started vermicomposting in 1997 with a 73-m2 area now produces 8 tons of vermicompost valued at P56,000 ($1,000) per month from materials (cow manure, rice straw, vegetable wastes, etc.) on its 10-hectare farm.
Vermicompost is applied in a fish pond at 0.75 ton/ha, 100-250 grams per fruit tree and 0.2-0.5 kg/m2 for field crops. In a five-year period, the CRTD has conducted vermicomposting training for 6,400 farmers from 816 organizations and more than 20 provinces in the country.
The International Symposium-Workshop on Vermi Technologies for Developing Countries co-organized by the PCAMRD-DOST, the Soil Ecology Laboratory of the Ohio State University and Philippine Vermi Society will be held in Los Baños, Laguna on November 16 to 18, 2005. The meeting will bring together researchers and industry stakeholders from the Philippines, United States, Australia and other countries.
Dr. Rafael D. Guerrero III is executive director of the Philippine Council for Aquatic and Marine Research and Development. He may be contacted at pcamrd@laguna.net.