Indira Sarangthem and Nongthombam Surbala Devi
In nature all dead matter is gradually acted upon by the forces of nature such as sun, wind, rain and microbes which serve to break down complex material into simpler molecules. If such material is left to decay on roadsides or market places, it begins to decompose and stink and also invites insects, rodents and bacteria which cause the spread of diseases. Instead, the process of decomposition can be used to convert organic waste which we generate everyday (in our homes, restaurants, offices, schools, canteens, markets, fields and gardens) to produce a rich compost which can help us keep our surroundings clean and green.
Composting is not a new concept. For centuries composting has been the best known method of making manure from organic matter to sustain better yields and healthy plants. It is the process of biological conversion of heterogeneous organic substrates under controlled conditions into a hygienic, humus rich, relatively biostable product. It conditions soils and nourishes plants. There are different techniques of composting viz., Vermicomposting, Effective Microorganism Technology (EM), Japanese Method of composting, enriched compost NADEP Method, etc. Among these, the Japanese method is one of the important composting techniques.
The advantage in the Japanese method is the use of vats (made up of bamboo mats/stone slabs/wooden planks) made to a length of 2.5-3 ft. Walls are made in such a way to allow easy aeration and the bottom of the vats should be plastered with cement to prevent leaching of nutrients to soil. Vats can be fabricated with the same dimensions from locally available materials.
Materials required for this composting are organic wastes such as : sugarcane baggage, coconut shells with coir, coconut branches and leaves, grass, straw, stover and residues, cow dung, poultry waste, biogas slurry, etc. Rock phosphate, gypsum and lime can also be added to enrich nutrient and fastening decomposition.
The Japanese method of composting used to take 120 days whereas vermicomposting used to decompose within 80-90 days. To hasten the decomposition process to 80-90 days, biofertilizers (microorganisms) can be used along with earthworms.
Varied organic waste is to be spread layer by layer. Yet, one small portion of about 5-6 inches space be kept free on one side of the vat to facilitate turning the residues regularly. Dry substrates such as sliced and broken pieces of coconut shells, sugarcane baggage, fibrous material, tender tree barks or pieces, wood ash, etc. should form the bottom layer of 10-15 cm height. These do not degrade easily as they contain lignin. Second layer of dry leaves, grass, residues, groundnut haulms etc. can be of 10-15 cm. These two hard and dry layers absorb moisture and nutrients leached from the top. Cow dung urine and biogas slurry can be used singly or mixed in a bucket of water and sprinkled over the layer. A very small amount of soil and ash can be sprinkled over this. In the third layer, green manuring crops (leaves of Pongamia, Albizzia, Dhaincha, sesbania, etc.), green grass and weeds, and crop residues can form 10-15 cm depth. These are rich in nitrogen. The fourth layer should contain organic waste rich in items like Calotropis, Datura and other weeds, tomato and tobacco crop residues, ash, poultry wastes, etc. forming 10-15 cm. Over these, two to three buckets of cow dung and biogas slurry can be sprinkled. This should seep down also to wet the lower surfaces. Above this 7-8 cm thick layer of vegetable waste and green biomass should be put. Generally, while preparing farm yard manure, paddy or ragi straw is also seen. If we have to derive greater benefits, these straw and stover samples should be cut into very thin pieces of 4-5 cm and should form a separate layer. These are rich in carbon and would provide energy to micro-organisms. They also have the nutrient ‘Silicon’ if green biomass is available along with dry straw, they can also be mixed in this small layer.
The sixth layer should exclusively contain 20-30 cm of cow dung. If stored in a heap for a long time, part of it would have dried up. These should be powdered. Over this, in small quantities, old compost powder, tank-silt and ash are sprinkled.
Turning should be done timely at an interval of 15 days with regular checking of moisture to avoid drying up of decomposing materials. This should be done for hastening the decomposition process. By decomposing 1 ton of biomass, 600-700 kgs of matured compost can be produced at the end.
Physical characteristics suggestive of maturity include
· Color: dark brown to black
· Odor: Acceptable (soil-like, musty or moldy) Unacceptable (sour, ammonia or putrid)
· Characterization: Identifiable wood pieces are acceptable but the balance of material should be soil-like without recognizable grass or leaves.
Thus, waste materials, a part for pollution, can be converted to useful manure using this technology of composting. Such manure is a good aspect for soil health development in producing optimum yield in organic cultivation of vegetables and other crops.
For further details contact:- Public Relation & Media Management Cell, CAU, Imphal. Email: [email protected]