UTILIZATION OF BIODEGRADABLE KITCHEN WASTES INTO ORGANIC FERTILIZER USING EARTHWORMS (LUMBRICUS TERRESTRIS)

ABSTRACT

One of the effective means to at least lessen the occurrence of our present garbage disposal problem is through the use of methods that are non-toxic, less expensive, lees-harmful, and yet equally effective. This project aims to provide for a natural and effective way of disposing garbage.

During the experiment, kitchen wastes were collected. The materials were shredded and placed in garbage bags with small holes. The temperature inside the bags was allowed to lower.

Three set-ups were prepared and were covered with plastic. The first box contained pure carabao manure, the second box contained 70 percent carabao manure and 30 percent processed kitchen wastes and the third box contained pure processed kitchen wastes. Lumbricus terrestris was placed in each set-up. The boxes were placed in a lighted area while maintaining their moisture. After drying, the Lumbricus terrestris were gathered. The resultant product, called “earthworm castings,” were then sun-dried and passed through a fine sieve to remove foreign materials.

Results showed that the castings from kitchen wastes and manure was highest in percentage total nitrogen, third highest in percentage total P2O5, and highest in percentage and highest in percentage total K2O.

It was concluded that organic kitchen wastes could be converted into a competitive organic fertilizer using Lumbricus terrestris. The organic fertilizer produced by using earthworms can compete in terms of nutrient contents with other organic fertilizers.

INTRODUCTION

A good alternative in solving our garbage problem is vermicomposing, the process in which organic wastes are decomposed naturally with the use of earthworms.

This project focuses on the efficient decomposition of organic kitchen wastes using Lumbricus terrestris and converting these wastes into organic fertilizer that can compete in terms of nutrient with other organic fertilizers.

This project provides additional research material in using earthworms as agents for decomposition of organic wastes. It aims to provide better and simpler means of waste disposal while producing something useful –organic fertilizer.

This project only tested the macronutrient contents of the harvested earthworm castings and compared them with those of other organic fertilizers. This proposal, however, did not include tests for macronutrient contents and other qualities of the castings produced. Also, this proposal did not test whether different waste materials produce different nutrient content for the castings.

REVIEW OF RELATED LITERATURE

Vermicomposing is the culture of earthworms in a composting system. The earthworms ingest organic matter as well as soil. As these materials pass through the earthworm’s body, they are mixed with digestive enzymes and reduced by the grinding action within the animal. The organic matter comes out of the earthworms as castings that contain plant nutrients. To work well, the earthworms prefer a well-aerated but moist habitat. They thrive well where farm manure or plant residues had been added to the soil. Most of them thrive best where the soil is not too acidic (Brandy, 1990).

Apelhof, as cited by Blackgold Vericompost Manufacturing Corporation (BVMC, 1987), reported that the Lumbricus terrestris, one of the 3000 species of earthworms presently identified, caught the interest of agriculturist and other earth worm enthusiasts. The Lumbricus terrestris or the African night crawler has a deep maroon shade, and measures from 4 to 12 inches in length.

Composting produces essential nutrients for plant growth. These nutrients are classified into macro and micronutrients. Relatively large amounts of macronutrients are required whereas micronutrients are required in small amounts only. These elements must be present in right proportions for when there is deficiency or excess of any element, this may seriously affect plant growth. The plants would develop symptoms of starvation or toxicity. The macronutrients include nitrogen, phosphorus and potassium. Every living cell contains nitrogen and its abundance leads to green, succulent growth. Phosphorus occurs in the protoplasm, with its great concentration in seeds thereby increasing their production. Potassium influences the uptake of other elements and affects both respiration and transpiration (Fitzpatrick, 1974).

METHODOLOGY

Kitchen wastes, composed mainly of vegetable and fruit peelings, were gathered, shredded, and placed in garbage bags with small holes. Temperature build-up inside the bags due to partial decomposition was measured and allowed to lower down for one month until three consecutive declining of temperature were achieved.

Three set-ups measuring 15 x 18 inches were prepared and were covered with plastic. One box contained pure carabao manure, the other box contained 70 percent carabao manure and 30 percent processed kitchen wastes and the last box contained pure processed kitchen wastes. About one hundred pieces of Lumbricus terrestris were placed

in each set-up. The boxes were placed in a lighted area to prevent the worms from escaping since the worms are light sensitive. The set-ups were checked daily and watered to keep moisture. Upon consumption of the contents of the boxes, as evidenced by the appearance of brown granular structures, the set-ups were spread on newspapers under the sunlight. The Lumbricus terrestris were gathered. The resultant product called “earthworm castings,” were then sun-dried and passed through fine sieve to remove foreign materials.

A laboratory analysis on the macrocontent of the earthworm castings was conducted by the Solis Department of the Sugar Regulatory Administration, La Carlota City, Negros Occidental. The nutrient contents were then compared with those of other organic fertilizers.

RESULTS AND DICUSSIONS

During the production of earthworm castings, the Lumbricus terrestris placed in the box, which contained pure processed kitchen waste, were found dead after one day. The death of the earthworms can be attributed to the acidity of the kitchen wastes. As organic matter decomposes, inorganic and organic acids are formed.

Carbonic acid, sulfuric acid and nitric acid are some of the acid formed by the organic decaying process. High concentrations of these acids may have caused the deaths of the earthworms in the set-up using pure kitchen wastes.

Both the castings harvested from the set-up that contained pure manure and from the set up which contained mixture of manure and kitchen wastes were tested for their Nitrogen-Phosphorus-Potassium micronutrient value. The results were compared with those of other available fertilizers.

SOURCE TOTAL K2O %TOTAL N %TOTAL P205

CASTINGS FROM 0.907 0.827 1.099KITCHEN WASTESAND MANURE

CASTINGS FROM 0.637 0.891 0.425MANURE ONLY

KITCHEN WASTES 0.494 0.742 0.726WITH TRICHODERMA

FARMER’S ORGANIC 0.794 1.626 0.958FERTILIZER

The results showed that the castings from kitchen wastes and manure ranked first in percentage total nitrogen and K2O and ranked third in percentage total P2O5. But this doesn’t mean that the castings produced would be very efficient in promoting plant growth because nutrient content of most organic fertilizers are usually in slow availability form when added in the soil. Nitrogen is held by soil colloids. Phosphorus compounds are mostly unavailable for plant uptake, some being insoluble forms that in time become quite unavailable for plant absorption.

Fortunately over time, potassium can be released to exchangeable form that can be quickly absorbed by plant roots.

SUMMARY AND CONCLUSION

Earthworm castings form kitchen wastes mixed with manure can compete with other organic fertilizers. Organic kitchen wastes can therefore be converted into competitive organic fertilizer using Lumbricus terrestris.

RECOMMENDATIONS

The study made use of only one specie of earthworm – Lumbricus terrestris. Other untested species may produce significant results. Also, the use of specific kitchen wastes or other organic trash as earthworm feed is recommended. This may have an effect on the chemical and physical composition of the castings and their use as an organic fertilizer.