Thursday, 10 January 2013

Vermitechnology and Climate Adaptation

Wish you all a very Happy New Year

Wastes of biodegradable nature are of major concern both in the villages and cities.  Enormous quantities of biodegradable wastes are being produced from farms, gardens, houses, apartments, markets and offices. Majority of the wastes are disposed off in the landfills while some end up in the open space or rivers and water bodies contributing to pollution. In the villages most of the farmers burn the wastes as it is easier to manage contributing to global warming and climate change.

Wastes if not managed scientifically pose a sequel of problems related to their management and associated health and environmental hazards. Bio-degeadable wastes comprise of vegetable and fruit peels, garden clippings, and kitchen garden wastes etc which are degradable.

Wastes, though considered waste are not mere waste. They are the misplaced resources which can be efficiently utilized with simple technologies. The waste management technology should not just aim at turning the waste benign, rather focus in bringing those resources back into place. In other words, the useless wastes should be transformed into a value-added product that can initiate income-generating enterprise. The approach should be “Turning filth to Wealth”.

Different methods are adopted to mitigate the biodegradable wastes generated. Composting is one of the techniques, which is widely followed. The composts that are produced by inappropriate methods reveal their adverse features during storage, marketing and use. The associated problems include foul odours, fire, environmental pollution, nuisance, insect infestation and bursting of compost bags. Phytotoxicity of such composts is also a serious problem, which impairs crop growth and yield when used in agriculture. In addition, there are problems of the compounds like amines, sulphamines, mercaptans, skatoles etc. To solve the gamut of problems related to the conventional composting methods,  vermitechnology  is one of the alternatives.

Vermitechnology is the method of converting wastes into compost by use of earthworms. Good quality compost is produced in a short period depending upon on the number of earthworms. In other words about 4-5 kg of wastes can be composted by 1000 worms (approximately 1 kg) in a day. The commonly used earthworms like Eudrillus sp. Perionyx sp., Eisenia sp. or any locally available surface feeding (epigeic) earthworms can be collected from the nearby soil and then used in Vermitechnology. A simple and efficient method of Vermitechnology “Pusa Vermitech” was developed during my Masters degree program at Indian Agricultural Research Institute (IARI), Pusa, New Delhi in 1996 which is low-cost and is ideal for the farmers. Now this method is widely adopted in India, Nepal, Sri Lanka, Italy and Costa Rica.

Vermitechnology can be undertaken in a tank or on the soil surface. The tank can be constructed with bricks or stones depending on the availability of materials. The height of the tank should be 0.75 metres, width 1 metre and length can be 3 - 4 metres or even more. The base of the tank should have a slight slope directing towards two drainage holes.

The methodology is simple and  can be carried out by adopting the following steps;
1. Basal Sand Layer
The first layer (5-10 cm) at the base is of sand as it helps in the drainage of excess water and also prevents the movement of worms into deeper layers of soil or out of the tank.

2. Dung Layer
On the top of the sand, a layer of one month old dung is laid. This layer is approximately 3-5 cm. thick.

3. Waste Layer
On the top of this dung layer all the biodegradable wastes are put and the tank is filled up to the brim (65 cm) with the waste.

4. Soil Layer
The wastes are covered with a thin layer (1-2 cm) of soil.

5. Dung Layer
Above the soil layer mature dung is uniformly spread (3-5cm) which forms the top layer in the tank.
In other words, the wastes are sandwiched by two layers of mature dung. The contents are moistened with water (40-50% moisture level) for 7 days to pre-decompose the contents. After pre-decomposition, worms are introduced (1000 worms which would be approximately 1 kg for 100-150 kg of wastes) and watered regularly to maintain 30-40 % moisture level for better activity of worms.

Watering is done in such a way the contents in the tank are not too soggy or too moist as it results in anaerobiosis of earthworms causing mortality. The tank is covered by a gunny sack in summer months to avoid evaporation of moisture. In places where the predators like rats, lizards, pigs are a major problem; the tanks can be covered with wire mesh to prevent them feeding on the earth worms.

Collection of Vermicompost
Vermicompost appears on the top of the tank in the form of pellets. When this layer of vermicompost becomes a few centimetres thick watering should be avoided for 3-4 days. The reduced moisture at the top layer will force the worms to move down towards the lower layers. The compost formed is heaped in the corners of the tank by gently scrapping with a shovel or a wooden raft and left for a day or two. By this method of collection of wastes the young worms and the adult worms are not damaged while handling. In this manner the compost can be collected every 7-10 days till 80% of the material is collected i.e 10-15 cm layer is left at the base. The tank/heap should be refilled with pre-decomposed wastes.

Pre-decomposition of wastes
Before filling the fresh wastes  into the tank it has to be pre-decomposed to avoid the heat that is generated during the decomposition process which otherwise can kill the earthworms. Also pre-decomposition helps to turn the wastes bit softer facilitating the earthworms to feed upon. Pre-decompostion is done as mentioned below;

1.      Spread a thin layer (10 cm) wastes and sprinkle cow dung and moisten it.
2.      Likewise make layers of waste and cow dung up to 0.5 metres height.
3.      Moisten the heap regularly with water for 10 days.
4.      During the process high temperature develops and cools down in a week.
5.      Check the temperature of the heap by inserting a stick.
6.      If the stick heats up, leave the decomposing material for 3-4 days more and when the temperature is normal then only it should be used.

Refilling the Tank or Heap
Such pre-decomposed material is put on the heap or tank up to 75% of its height. The standard procedure of Vermitechnology as mentioned above is continued i.e over the pre-decomposed waste, thin layer soil is spread and above it dung is spread. The worms come on the top and start feeding on the waste.  

1. Check the temperature of heap /tank by introducing a stick. If the stick heats up worms should not be introduced nor refilled. Nowadays temperature measuring probes are also
2. The tank /heap should be moistened with water regularly.
3. Appropriate shade should be provided at the site where Vermitechnology is undertaken.
4. Wherever the predators like rats, lizards, pigs etc., are found, wire mesh should be put on the top of the tank.

It is very important that the method adopted  should be scientific degrades the waste faster, the end product i.e. compost should fit into the basic criteria (i.e. quality parameters) of marketing of manure. The compost  should not have any bad odour which will not be acceptable by the users. To be the choice of consumers, the final product should be friable and uniform with positive visual characteristics and attractive packaging. Mere degradation is not composting, rather composting is a scientific way of desired degradation.

There is a tremendous scope for the production of quality manure by vermitechnology. The growing awareness about organic farming, home and kitchen gardens  world over is an added advantage and a positive step in launching a quality product at this juncture. This will not only manage the wastes but also would generate income

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