The bio-conversion time of organic wastes varies based on its contents

ex. tamdi bhazi  15days using Eudrilus eugeniae(EU)

      Tomato peel waste 35 days using EU

Potato peel 35 days (EU+EF)

Raddish 70-80 days

Mixed vegetable waste 45 days

Ground nut peel 70 days

Reffer to 

Dynamics of the Soil-Earthworm-Plant Relationship: A Review. Dynamic soil and Dynamic Plant p (Special Issue II on Vermitechnology-2010).P 1-21.

The rate of compost production is influenced by raw material (size and type), earthworm (age, life cycle, quantity, i.e. earthworm: raw material ratio) and environment (temperature etc). In case of Eisenia fetida, it’s desirable to clean (harvest) compost in 60-75 days so as to facilitate completion of earthworm’s life cycle, irrespective of raw material or quantity of earthworm used. In summer months it may be 60±5 days and in winter 70±5 days.

Michela , very interesting question . My colleagues have very ably responded to your question . I want to add further , time taken to develop the mature compost , is by and large dependent on the C:N ratio of the composting material , the most pivotal of all. I  think,  all of you will agree .

Colleagues, interesting discussion on vermicomposting. In a biochemical reaction the enzyme ,the substrate and temperature (pH) are very important. In vermicomposting also the substrate (feed material, fresh or partially decomposed palatable to earthworms),earthworms number (amount of worms added) and temperature are important. If a limited amount of organic substrate is consumed and passed through the gut of earthworms, the process will be completed in short time.But  ,if the substrate or organic material is large in amount in relation to earthworms inoculam added,the time taken for vermicomposting will be longer.It is also a question on how much time we allow for maturation like ordinary composting cool phase.Please go through the following paper for better appreciation of the process and period of Completing.

Towards modelling and designing vermicomposting systems. Mechanism of compost ing/vermicomposting and their implications by Tasnum Abbasi,S. Gajalakshmi and S.A.Abbasi Indian Journal of Biotechnology vol,8,April 2009,pp177-182  Pdf IJBT8(2)177-182.pdf nopr.niscair.res.in>bitstream

The major determinants are carbon Nitrogen ratio of the waste material, population of worms and the condition under which vermicompensating is done. 

Dr.Borah and other colleagues, do you think there is a need for cooling/maturation phase in vermicomposting? If it is required ,what is the duration? If cooling period is not  required, what is the time taken by earthworms from ingesting food to excretion of warmicasts?Can we not collect the vermicasts after every few hours/day Iike a batch process in industry and keep it aside?

Dr A S Rao sir, it is a pertinent aspect and needs to be observed. But, practically it would require tremendous effort to separate casts from the raw materials (larger size) at initial stage when decomposition is very less. Accordingly, the experimental set up be designed carefully. Initially, collection of casts may be taken at weekly interval, at least for first 3 to 4 weeks, and then interval may be reduced. Suggestions from experts are welcome.

Dear  colleagues. important  point is whether we can reduce the  period  of composting?By reducing feed(substrate) and increasing the worm culture and by keeping them on  some sieve,can we collect the wormcasts like  poultry droppings?Any other innovative method can be  used to collect the worm casts  frequently.

Anil Kumar , reducing the depth of vermibed will produce much lesser quantity of final product , thereby , the very purpose of vermicomposting may not be fulfilled. Have you tested some multiple microbial inoculation  to reduce the time taken for compost maturity  ?.  I agree with your second point .

A K Srivastava has rightly pointed about the impact of reducing depth of composting material. Further, it's observed that reduction in depth does not maintain optimum temperature, and needs frequent watering due to higher evaporation loss. The best way to enhance composting ids to add sufficient earthworms (2 kg/square meter), preferably of similar age (practically very difficult for one other than a zoologist/entomologist).

rightly said Nilay , such things need to be standardized , you cannot practice so rigid parameters of composting in a given climate , since lot depends on the prevailing conditions inside compost yard vis-à-vis outside . But addition of some decomposers will surely hasten the compost maturity .

Thank you all for so many helpful insights. Can anyone tell me why reducing the vermibed depth will result in less vermicasts? Is this because there are less worms? Or does this stress the worms and cause them to be less efficient decomposers?

Michela , as rightly said , vermibed of more than 1feet , probably induce such uncomfortability to earthworms  , may be due to restriction in  exchange of oxygen between oxygen stored within the bed to outside environment , thereby , causing unnecessary stress to worms. therefore, better to have more number of beds than increasing the depth of vermibed. In this regard , I agree with  statement of Anil kumar .  

Dr Anoop has nicely explained. I would like to add a point from our observation and experience. The depth of vermibed is an important aspect to study. Compost tank filled to a height of more than 120 cm exerted high pressure and temperature resulting in formation of cakes/sticky product at the bottom, possibly due to transformation of sugar's/polysaccharides. On the other hand, as has been discussed by all, reducing depth to less than 60 cm does not maintain congenial environment (temperature/ moisture/ light) for the worms, except maintain the same through precision set up (against the principle of low cost composting). Looking forward for your comments!!

 Dear colleagues interesting discussion on vermi-composting especially the period of composting.From the discussion it appears to me that the period composing can be reduced or the process of composting can be accelerated by reducing the depth of material/bed to around 60 cm,by increasing the worms inoculation per square meter to 2 kg and by optimization of temperature.The life cycle of the earthworms is also important as pointed out  by Dr.Borah.I think two points need more attention,one how to periodically collect the wormcasts(say weekly) and also what is the criteria for attaining the maturity of vermicompost similar to other composts.

Sir., A S RAO

I fully agree with you for the two points which you have mentioned

one more important factor is overloading of VC units should be avoided

which leads to anaerobic conditions.

VC unit for potato peels suggested thickness of organic loading is 15 cms thickness harvested every month using only Eudrilus eugeniae, Eisenia fotida, and co culture of both

VC unit for sugarcane trash 30 cms thickness using P elongate harvested after 45 days

Dr.Prakash,your studies on vermicomposting of potato peels and sugarcane trash are interesting.The depth of organic loading is much less(15-30 cm ) compared the depth suggested by other colleagues.Also the period of composting(harvesting) is less(30-45 days).Will the sugarcane trash need pre-composting before allowing the earthworms to feed?Have you assessed the quality of compost in both the cases?I understand that the earth worm species differ in their feeding habit.Is it related to depth of bed for vermicomposting?

I put the food to worms at 15 cm of depth and I recover manually vermicast en surface each few days. It is an excellent system of deep bedding in vermicomposting because increase aireation and productivity.