WASTE CONVERSION TO VERMICAST BY EISENIA FOETIDA GIVEN FOUR TYPES OF ORGANIC SUBSTRATES IN THE NATURAL MALAYSIAN ENVIRONMENTAL CONDITIONS

Abstract

The present study was carried out to determine the ability of the earthworm Eisenia foetida to convert four different types of organic wastes into vermicast in the natural Malaysian environmental conditions. The experiment was carried out in the worm house with the ambient temperature recorded as between 26°C–33°C and relative humidity ranged between 65%–80%. The water content of the raw organic matter ranged from 71.0%–95.2%. The highest water content of the substrates was in the shredded banana trunk (95.2%), followed by cafeteria waste (91.0%), shredded newspaper (76.3%) and cow dung (71.0%). The pH_KCl and pH_H2O of the cafeteria waste increased 86.3% and 90.2%, respectively after vermiculture treatment. The increase in pH was the highest when the raw material was acidic (4.16). Only slight increase or decrease (i.e. between 6.7%–17.2%) occurred when the raw materials were slightly alkaline (7.40–7.86). Regardless of types and initial pH of the raw materials, pH of vermicast has shifted to near neutral or more alkaline (6.49–8.35). In general, exponential increase in growth of the earthworm in all the organic wastes tested occurred until the 5th day of vermicomposting and declined thereafter. The trend in growth increment was similar in all types of organic wastes. Weight increment commenced immediately after the worms were inoculated onto the media. Earthworms grown on cafeteria waste showed the highest growth increment, followed by cow dung, shredded banana trunk and shredded newspaper. Cafeteria waste was also found to be the fastest to completely convert to vermicast. The raw materials completely turned to vermicast within 36.2 ± 1.3 days for cafeteria waste, 43.8 ± 1.14 days for shredded banana trunk, 47.4 ± 0.84 days for shredded newspaper and 58.2 ± 0.84 days for cow dung. Vermicast production was 41% of the earthworm's body weight per day for cafeteria waste, followed by 34% for banana trunk, 32% for shredded newspaper and 26% for cow dung. In the natural Malaysian environmental conditions, the ability of E. foetida to convert organic waste into vermicast vary with type and quality of the substrate used. Growth increment of E. foetida was paralled with the rate of waste conversion into vermicast, e.g. higher growth increment resulted in faster conversion of wastes into vermicast.

Kajian ini dijalankan bagi menentukan kebolehan cacing tanah Eisenia foetida menukar empat jenis sisa organik kepada vermikas pada persekitaran semula jadi Malaysia. Eksperimen dilakukan di rumah cacing dengan suhu persekitaran di antara 26°C–33°C dan kelembapan bandingan sekitar 65%–80%. Kandungan air bahan mentah organik adalah sekitar 71.0%–95.2%. Kandungan air paling tinggi bagi substrat ialah pada carikan batang pisang (95.2%), diikuti oleh sisa kafeteria (91.0%), carikan surat khabar (76.3%) dan najis lembu (71.0%). pH_KCl dan pH_H2O sisa kafeteria meningkat masing-masing sebanyak 86.3% dan 90.2% selepas rawatan vermikultur. Peningkatan pH paling tinggi sebanyak 86.3% berlaku pada bahan mentah berasid (4.16). Hanya sedikit peningkatan atau penurunan (iaitu di antara 6.7%–17.2%) berlaku apabila substrat bersifat sedikit alkali (7.40–7.86). Tanpa mengira jenis dan pH awal bahan mentah, vermikas yang terhasil oleh vermikultur menunjukkan nilai pH yang berbeza, bersifat hampir neutral atau lebih alkali (6.49–8.35). Secara am, peningkatan eksponensial tumbesaran cacing tanah dalam semua jenis sisa organik yang dikaji berlaku sehingga hari kelima proses vermikompos dan menurun selepas itu. Corak tumbesaran adalah serupa dalam kesemua jenis sisa organik. Penambahan berat cacing berlaku sebaik sahaja selepas cacing diinokulasi ke dalam media. Cacing tanah yang hidup dalam sisa kafeteria menunjukkan tumbesaran paling tinggi diikuti oleh najis lembu, carikan batang pisang dan carikan surat khabar. Sisa kafeteria juga didapati paling cepat tertukar sepenuhnya kepada vermikas. Bahan mentah tertukar sepenuhnya kepada vermikas dalam masa 36.2 ± 1.3 hari untuk sisa kafeteria, 43.8 ± 1.14 hari untuk carikan batang pisang, 47.4 ± 0.84 hari untuk carikan surat khabar dan 58.2 ± 0.84 hari untuk najis lembu. Penghasilan vermikas ialah 41% berat badan cacing per hari untuk sisa kafeteria, diikuti 34% untuk carikan batang pisang, 32% untuk carikan surat khabar dan 26% untuk najis lembu. Dalam keadaan persekitaran semula jadi di Malaysia, kebolehan E. foetida menukar sisa organik kepada vermikas berbeza bagi jenis dan kualiti substrat yang digunakan. Peningkatan pertumbuhan E. foetida adalah selari dengan kadar pertukaran sisa buangan kepada vermikas, iaitu peningkatan pertumbuhan mempercepatkan penukaran sisa buangan kepada vermikas.