Earthworm gut is the site of production of genuine humic acids which are distinct from the polysaccharide-gum humic acids. About half of the gums secreted by earthworm are in form of mucoproteins that help stabilizing pore space distribution. The earthworm soil casts are richer in available plant nutrients (nitrate nitrogen, exchangeable Ca, Mg, K and P) and organic matter. The earthworms through their casts and dead tissues supply about 60-90 kg N to the soil. Earthworm eats on fungal mycelia. Earthworms convert farm waste and organic residues into high quality compost. For this, Eiseniafoetida, Perionyxexacavatus, Eudrilluseuginiae and Lumbriusrubellus are important. These species can be cultured on organic wastes and dung. The technique of culturing them is called vermiculture and using these for decomposing residue to make compost is called vermicomposting.
About 1000 adult earthworms can convert 5 kg waste into compost per day. The earthworm assimilate 5-10% of the substrate and rest passes through the alimentary canal and is excreted as cast. Earthworm cast contains nutrients, vitamins, hormones and antibiotics.
Vermi-compost is a stable fine granular organic matter, when added to clay soil loosens the soil and provides the passage for the entry of air. he multifarious effects of vermicompost influence the growth and yield of crops.
Definition of vermicomposting:
Vermicomposting is a method of making compost, with the use of earthworms, which generally live in soil, eat biomass and excrete it in digested form. This compost is generally called vermicompost or Wormicompost.
Definition of Vermiculture:
Vermiculture means scientific method of breeding and raising earthworms in controlled conditions.
Vermitechnology:
Vermitechnology is the combination of vermiculture and vermicomposting. Thus, earthworms can be used in the following areas.
1. For development of arable soils, turnover of soil, break down of plant organic matter aeration and drainage
2. For production of useful products like vermifertilizer and worm tissue for animal feed.
3. For maintenance of environmental quality and monitor of the environment for soil fertility, organic and heavy metal non-biodegradable toxic material pollution.
Types of Earthworm :
Types of earthworms in vermicomposting Earthworms belong to phyllum Annelida of Animal Kingdom. They are long and cylindrical in shape and size having a large number of grooves. There are about 3000 species of earthworms in the world which are adapted to a range of environment. More than 300 species have been identified in India. Although, hermophrodite, two mature earthworms are required to propagate. At the time of egg laying, the clitellum is transformed into hard, girdle like capsule called cocoon. Shedding of cocoon ranges from 1 to 5, only a few of them survive and hatch. The juveniles and again formation of cocoons takes a period of 50-60 days. Normally, the average life span of earthworms varies with species ranging from 1 to 10 years.
Epigeics (surface feeders) are important in vermicomposting.
The epigeics such as Eiseniafoetida and Eudriluseugeniae are exotic worms and Perionyxexcavatus is a native one being used for vermicomposting in India. Epianecic are feeders on leaf litter and soil at upper layers of soil. This group such as Lampitomauritii is indegenous and is active in in-situ decomposition of organic wastes and residues in soil. Both epigeics and epianecics groups of earthworms areslender, shorter in length and red to dark brown in colour. They have high reproduction activityand efficient in recycling of organic materials. Increased attention has been paid to Eiseniafoetida and Eudriluseugeniae which have been found to be potential agent in vermicomposting of wide range of agricultural wastes and can grow at a wide range of temperature varying from 0-40 ◦C. However, the optimum temperature ranges from 20-30 ◦C.
Mechanisum of Vermicomposting:
Mechanism of vermicomposting Materials consumed by worms undergo physical breakdown in the gizzard resulting in particles < 2 µ, giving thereby an enhanced surface area for microbial processing. This finally ground material is exposed to various enzymes such as protease, lipase, amylase, cellulase and chitinase secreted into lumen by the gut wall and associated microbes. These enzymes breakdown complex biomolecules into simple compounds. Only 5-10% of the ingested material is abosrbed into the tissues of worms for their growth and rest is excreted as cast. Mucus secretions of gut wall add to the structural stability of vermicompost.
Vermiculture industry or vermicompost preparation:
1. Basic raw material: Any organic material generated in the farm like bhusa, leaf fall etc., Horse dung, due to the risk of Tetanus virus, lethal to human beings is not advisable to be used as feeding material for earthworms. Paddy husk, merigold and pine needles have also advised to be used as feeding materials for earthworms.
2. Starter: Cow dung , Biogas slurry, or urine of cattle
3. Soil animal: Earth worms (Species: Eiseniafoetida)
4. Thatched roof/vermished.
Favourable conditions of earth worms in the composting material:
A.pH: Range between 6.5 and 7.5
B. Moisture: 60-70% of the moisture below and above range mortality of worms taking place
C. Aeration: 50% aeration from the total pore space
D. Temperature: Range between 18 0C to 35 0C
Procedure It is mostly prepared in either pit or heap method.
The dimensions either heap or pit are 10 x 4 x 2 feet. The length and width can be increased or decreased depending on the availability of material but not the depth because the earthworms’ activity is confined to 2 feet depth only. First of all select a site which is not under any economic use and is shady and there is no water stagnation. The site should also be nearby to water source.
1st layer: bedding material of 1" thick with soft leaves
2nd layer: 9" thick organic residue layer finely chaffed material
3rd layer: Dung + water equal mixture of 2" layer. Continue the layer up to pile to ground level in the case of pit method and upto 2ʹ in heap or surface bed method. Protect the worms against natural enemies like ants, lizards, snakes, frogs, toads etc., Maintain proper moisture and temperature by turnings and subsequent staking. At the day of 24th, 4000 worms are introduced in to the pit [1m2 =2000 worms] without disturbing the pit by regular watering the entire raw material will be turned into the vermicompost in the form of worm excreta. The turnover of the compost is 75% [the total material accommodated in the pit is 1000 kg; the out turn will be 750 kg]
Harvesting of the vermicompost:
Harvesting of the vermicompost from the pit Stop watering before one week of harvest. Sometimes the worms spread across the pit come in close and penetrate each other in the form of ball in 2 or 3 locations. Heap the compost by removing the balls and place them in a bucket. However, under most instances, top layer has to be disturbed manually. Earthworms move downward and compost is separated. After collection of compost from top layers, feed material is again replenished and composting process is rescheduled. The material is sieved in 2 mm sieve, the material passed through the sieve is called as vermicompost which is stored in a polythene bags
Precautions:
1. Do not cover vermicompost beds/heaps with plastic sheets because it may trap heat and gases.
2. Do not overload the vermicompost heap to avoid high temperature that adversely affect their population.
3. Dry conditions kill the worms and waterlogging drive them away. Watering should be done daily in summer and every third day in rainy and winter season. 4. Addition of higher quantities of acid rich substances such as tomatoes and citrus wastes should be avoided.
5. Make a drainage channel around the heap to avoid stagnation of water particularly in high rainfall areas in rainy season.
6. Organic materials used for composting should be free from non-degradable materials such as stones, glass pieces, plastics, ceramic tubes/bulbs etc.
Natural enemies and their control:
The important natual enemies of vermiculture are ants, termites, centipedes, rats, pigs, birds etc. Preventive measures include treating of the site with chlorpyriphos 20 EC at 2 ml/l or 4% neem based insecticide before filling the heap.
Transportation of live worms:
Live earthworms can be packed with moist feed substrate in a container (card board/plastic) with provision of aeration. Feed substrate quantity should be roughly 0.5-1.5 g/individual for 24 hours of transportation journey. Culture should contain cocoon, juveniles and adults because sometimes adults do not acclimatize to new environment and may even die. Under such circumstances cocoons are helpful for population build up of earthworms.
Conversion rates:
- 1000 earth worms may convert 5 kg waste material per day 1000 worms weighs about a kilogram
Advantages of composting over direct application:
1. There will be no immobilization in compost because of narrow C:N ratio
2. Application is easy, because the compost is humified and have a structure of crumb and granular.
3. It is hygienic, pathogens and weeds seeds are destroyed.
The rate of application is as Field crops 5-6 t/ha; vegetables 10-12 t/ha; flower plants 100200 g/sqft; fruit trees 5-10 kg/tree.
Advantage of vermicompost
1. Vermicompost is a rich source of nutrients, vitamins, enzymes, antibiotics and growth hormones. So it gives disease resistance to plansts. Nutrient content of vermicompost is higher than traditional composts. It is a valuable soil amendment.
2. Vermicompost harbours certain microbial populations that help in N fixation and P solubilisation. Its application enhances nodulation in legumes and symbiotic mycorrhizal associations with the roots.
3. Superiority of vermicompost over other synthetic growth media is more pronounced in plant nurseries. It can be used as rooting medium and for establishment of saplings in nurseries.
4. It improves taste, lusture and keeping quality of the produce.
5. It has immobilized enzymes like protease, lipase, amylase, cellulase and chitinese which keep on their function of biodegradation of agricultural residues in the soil so that further microbial attack is speeded up.
6. It does not emanate foul odour as is associated with manures and decaying organic wastes
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