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Vermicompost

Vermicompost
 

Compost: A mass of rotted organic matter made from waste is called compost. The compost made from farm waste like sugarcane trash, paddy straw, weeds and other plants and other waste is called farm compost. The average nutrient contents of farm compost are 0.5 per cent N, 0.15 per cent P2O5 and 0.5 per cent K2O. The nutrient value of farm compost can be increased by application of superphosphate or rock phosphate at 10 to 15 kg/t of raw material at the initial stage of filling the compost pit. The compost made from town refuses like night soil. Street sweepings and dustbin refuse is called town compost. It contains 1.4 per cent N, 1.00 per cent P2O5 and 1.4 per cent K2O.

Farm compost is made by placing farm wastes in trenches of suitable size, say, 4.5 to 5.0 m long, 1.5 m to 2.0 m wide and 1.0 m to 2.0 m deep.

Farm waste is placed in the trenches layer by layer. Each layer is well moistened by sprinkling cow dung slurry or water. Trenches are filled up to a height of 0.5m m above the ground. The compost is ready for application within five to six months.

Production of Phosphocompost: The addition of insoluble source of P to enrich compost is a more rational and practically useful approach since solubilization of insoluble P occurs during composting. Following compostable materials consisting crop residues, grasses, weeds, tree leaves, animals feed wastes or their mixtures and cattle dung are used along with P sources:

 

Phosphocompost: Phosphocompost or P-enriched compost can be made by mixing rock phosphate @ 5% P2O5 with the composting mass. To produce 1000 tones phosphocompost on dry weight basis following materials are required (Mishra 1992);

800 t organic refuse, crop residues, leaves, grasses

100 t cattle dung or biogas slurry

100 t soil

50 t well-decomposed FYM/compost/sewage sludge

265 t rock phosphate

 

Night Soil: Night soil is human excreta, both solid and liquid. It is richer in N, P and K than farmyard manure and compost. Night soil contains on an average 5.5 per cent N, 4.0 per cent P2O5 and 2.0 per cent K2O

 

Sewage and Sludge: In the modern system of sanitation adopted in cities and towns, a human excreta is flushed out with water which is called sewage. The solid portion in the sewage is called sludge and liquid portion is sewage water. Both the components of sewage are separated and are given a preliminary fermentation and oxidation treatments to reduce bacterial contamination and offensive smell.

 

Vermiculture technology: In vermiculture technology, the potential of earthworms as natural bio-degraders of non-toxic organic wastes for soil improvement and nutrient mobilization is being exploited. Earthworm population in organic matter rich soils act as natural bioreactors, harness beneficial soil micro flora, destroy soil pathogens and convert organic wastes into valuable product such as bio fertilizers, vitamins, enzymes, antibiotics, growth hormones and pertinacious worm biomass.

Role of earthworms in sustainable agriculture Effect of earthworm on soil fertility: Earthworms after having properly established in the soil modify soil physicochemical- biological characters of the soil and enhance nutrient cycling by ingestion of soil and humus and converting it into nutrient rich cast. The early availability of various nutrients such as P, Ca, Na, Mg, K etc are much higher in earthworm cast then in the surrounding soil.

 

Earthworm in soil and water management: A ideal population of about 2-4 lakh worms per ha can make permanent structurally stable burrows in soil, which allow water infiltration up to a depth of 120 mm. Each burrow acts as a micro-dam and prevents runoff losses and enables the soil to sustain moisture for longer period of time. The earthworm casting are stable and do not break into smaller pieces, preventing the soil erosion by wind and runoff water.

 

Earthworms for effective waste management and conversion of wastes into nutrient rich compost: Vermiculture technology is being harnessed to set up units for cost effective treatment of various non-toxic solid and liquid wastes from industries, agricultural operations and households. The product of such unit known as vermicompost is very high quality nutrient rich source and is being increasingly exploited for sustainable organic farming.

 

Earthworm for diseases and pest management: Healthy soil has a balanced population of beneficial soil micro flora and burrowing earthworms. This reduces the population of soil pathogens through competition and antibiosis. Almost all insect and pathogenic attacks are targeted to weak plants or imbalance nutrition plants. Earthworms produce casts, which provide balanced nutrition to the plants, thus giving them tolerance to the pest attack.

 

Earthworms for better quality of crops: Crops grown organically, with slower growth rates and greater physiological maturity harvest, have higher quality attributes and longer storage life.

 

Earthworms for sustainable agriculture: Vermicastings are used in agriculture to change cultivation practices from chemical to organic agriculture without loss of yields. Eroded and saline soils can be restored and reclaimed through vermiculture biotechnology.

 

Earthworms as vectors if beneficial microorganisms: Various microorganisms are being used presently as bio-fertilizers to improve crop productivity. But by routine application methods, they are able to spread in limited soil environment. The activity of earthworm promotes their dispersal and wider reach in soil. Also the vermicasting provide very ideal niche for their faster multiplication and increase activity.

 

Selection of site:

For continuous and economic production of vermicompost following parameters should be given due consideration.
Enough of organic material is available in close vicinity on regular basis.
Suitable containers/tanks or large composting beds are available preferably under sheds.
Easy availability of earthworm species.
Basic facilities of pre-treatment of composting material are ready and necessary tools are available for handling.
 

Vermicomposting raw material: The biologically degradable and decomposable no-toxic organic matter is used in vermicomposting. Commonly used composting materials are animal dung, agricultural waste, forestry waste, leaf litter, waste papers, cotton cloth, city refuse, biogas slurry and no-toxic industrial waste of organic nature.

 

Pre-treatment of composting material: Sorting and separation: In this the waste material is made free from non-decomposable materials like plastic, stones, metal, glass, ceramics etc.

 

Drying: Sorted clean material is cut into small pieces and heaped on ground up to maximum 1ft thickness and exposed to sun for 1-2 days. This will help in killing several unwanted organisms and remove foul smell.

Heavily insect-infested vegetable waste can be subjected to chemical treatment such as 4% aqueous solution of neem insecticide. To avoid fly breeding on heaps neem insecticides can be used as spray over heaps.

 

Requirement for vermicomposting:

Container/vermicomposting bed: Depending upon the requirement and availability of waste material to be composted, the size of the container or bed can vary. For a small size indoor unit a bin of approximately large bucket size to about 2m x 1.5m x 1m size having aeration tubes all around the side walls can be used. For large appropriate size beds/bricks tanks under a thatched roof shed can be constructed. Composting can also be done in simple heaps under thatched roof sheds. Various designs of vermicomposting containers, beds and tanks are given in diagrams.

 

Bedding material: This is the lowermost layer of the earthworm fed substrate that is required to be vermicomposted. For this any biodegradable matter is used like banana leaves, banana stem peels, stems of crops, grasses or husk, waste or discarded animal feed etc.

 

Vermicomposting process: Although various variants of technology are available depending upon the size of unit and construction of composting beds and pre-treatment processes, but the basic process is almost same and involves following steps:

Spread the bedding material in the bottom of the container or bed for up to 2-6 inches. If composting is done in small containers or bins then spread a layer of pebbles, stones and broken brick pieces up to 2-4 inches below the bedding material. Spread 2 inch layer of fresh cow dung followed by alternate layer of feeding material and dung up to 2ft. Cover with a layer of soil and maintain moisture at 50-60 per cent. Initially the temperature will rise. After the temperature has come down inoculate with the worm and spread one more layer of partly digested feeding material. Cover the heap with moist gunny bags. Within 25-30 days’ time upper layer will be ready for harvesting.

Alternatively the bed is filled with partly digested feed material and partly digested and dried cow dung or biogas slurry. In this case there will be no temperature increase. This can be inoculated with the worm immediately and covered with a layer of feed material and soil.

Moisture is maintained by spraying the water as and when required.

The feed is to be placed uniformly in a layer over the culture bed ad replenished as and when it disappears from the surface. When compost is ready for harvesting watering is stopped for 2-3 days, so that worms can go down in the lower bedding surface.

Scrape out the compost and dry. If some earthworms and their present remove them manually. Dried compost is sieved, further dried and stored in bags.

Fresh feed material should be placed immediately after removing the compost, maintain moisture and cover with moist gunny bags. Within 6 months’ time worms will eat up the entire bedding material. At this stage empty the entire contents of the bed after stopping the water for 4-5 days and start the entire process afresh (yadav, 2003).