Thanks Shalini for first feedback , but you know , I am very apprehensive about the composting ability of dried/dead  citrus plants .  It has mostly hemi-celluloses plus huge amount of lignin. A raw material having C:N ratio of 500-700:1 , irrespective of the material,  we use as an inoculum , how many days you expect to generate a normal compost of 25-30:1 from dead citrus trees .

I'm afraid that the raw material you mentioned  is inappropriate for composting (brewed citrus waste) especially with C/N ratio of 500-700. You might use another raw material with very low C/N ratio (chicken manure) to allow microbial activity to degrade simple (glucose/fructose...), complex (hemicellulose, cellulose, protein...) and very complex molecules (lignine) gradually. The optimum start up C/N ratio 30 and the microbial C/N ratio is 10, so you so far from that with C/N ratio of 500-700. Please find attached my conference paper and use the formula in it to allow you to adjust the C/N ratio of the mixture. The elemental analysis of total nitrogen and total organic carbon are mandatory (weight/weight based analysis) to perform the calculation.

Conference Paper Dynamic composting optimization through CN ratio variation a...

Yes, you can make good compost from dried and woody trees. You have to take the follwing steps while you are preparing the compost.

1. The optimum C:N ratio of feed for efficient composting is 25 to 35 and particle size is 10mm (for forced aeration ) and 50mm for long heap and natural aeration. So, you have to cut thematerial accordingly and reduce the C:N ratio of your material by applying animal manure (specially poultry manure in your case as you mentioned the C:N ratio is very wide i.e. 500-700:1) along with some urea so that your C:N ratio of the material may goes down to near desire range for quick decomposition.

2. As your material is rich in lignin and hemicelluloses you should inoculate the compost material either with Mycena polygrama or Lepiota amianthina or Clavaria dendroidea, which are considered to be good lignin decomposing organisms. Simultaneously you may inoculate also with Lactobacillus or Acromobacter or Sporocytophaga which are very good to decompose hemicelluloses and they are compatible with the previous lignin decomposers already mentioned.

3. During the decompsition process you should be assured that the moisture content maintained 50 to 60%, temperature 55 to 60 degree celcus at least for three days and maintain oxygen level 10 to 18 % (0.6 to 1.8 cubic meter air/day/kg).

If you follow the thing then your compost may be ready between 120 and 150 days. The ideal character of the compost before harvest should be N 1-3%, P2O5 1.5-3%. K2O 1-15%, moisture content 15-25%, organic C 20%, C:N ratio 10-15:1. 

Nice account of composting , you have provided to me  using a raw material having such a high C:N ratio . And , still interesting to know the possible composition of the end product. Is there any  well defined procedure to compute the composition of composted material , or it is just an estimate .

It depends upon how much urea and poultry manure you are adding initially to bring down the C:N ratio at least 40 to 50:1  to start composting. But I hope you may get the final product of the following composition; N-1.5%, P2O5 - 2%, K2O- 6-8%, organic carbon - 22-25%. The composition also may vary as per the method you are using for composting as well as whether you are following natural system or mechanized system. 

Is this composition simply an estimate or any mathematical equation ,  you have used , just I wanted to know for my knowledge.

What do you think about the usage of Trichoderma,  Bacillus ,especially Peanibacillus  and mycoides etc  in preparing citrus wood -based compost .

Dr.Srivastava,the thee main hurdles for  composting of dead citrus trees  are particle size ,C:N ratio,and culture/other manure requirement.When sawdust can be composted,citrus trees  can also be composted.But is it worth composting or use for other purposes,one has to think. How to reduce the particle size of trees? .If your C:N ratio is correct,you have to invest a lot on fertilizer N or N rich manure  supplementation and also a lot of water .Ultimately the quality of the manure produced depends on your inputs of other manure/ fertilizer  especially for N and P .Young twigs and  fallen  leaves can be composted  like green composting technologies.

Dr.Srivastava,I can suggest  two options for use of the dead trees-composting of relatively soft portions/tender parts  using green composting technologies being followed for tree prunings and preparation of biochar from woody portions.Of course both the options require some R&D efforts.

Thanks so much Dr Tarafdar and Dr Rao. Nice to interact on such a issue. Actually , I was willing to see , how best we can use these dried treed of citrus which happens to be such a large number annually. It is the a biggest  possibility of recycling the perennial waste , a kind of orchard waste , synonymous to farm waste . But , the major bottleneck is such a high C:N ratio , makes whole exercise of composting little time consuming and highly technical as well, since many of the composting conditions are yet not known. How do you see the role of biochar in such high clay l soils where drainability of smectite rich soils is inherently so low , and citrus happens to be so vulnerable to poor drainage conditions ( Fro example, development of soil borne diseases in citrus), it could further hamper the drainage conditions once we add biochar in such clay soils.

 Dr.Srivastav, I agree with your first point regarding composting of woody trees but I do not agree with your view on bad effects of biochar on black soils because of its high water holding capacity  .Please read some more literature and also conduct  some preliminary studies.Please refer to the following paper

Biochar from sawdust, maize stover and charcoal:Impact on water holding capacities(WHC) of three soils from Ghana 19th world  soil science,soil solutions for a changing world 2010 1-6,August,,Brisbane,Australia .

 Dr Rao, thanks again for responding . Infact in this part of the country where citrus is grown on  smectite rich soils ,  improving water transmission properties , we really don't intend to inflict  ,since  WHC of soils is enough to facilitate the genesis of foot and root rot diseases . In this context only , I passed on my previous response . Our communication seems to  divert  a bit from its main objective . Can you please guide me,  how to prepare biochar from dead citrus trees,  if you have any authentic source of information , I will be really  glad. But , please keep in mind about its feasibility  .

I have had some experience of chipped Avocado & orchard shelterbelt trees and we have produced a fair compost quality using 2% dilution Fish hydrolysate  to moisten the heap. When there is a fair amount of leaf in the wood chip initial fermentation is not bad. The windrows should not be more than 1.5M high otherwise the heap overheats. After the initial fungal stage nears completion then blend with animal manure 50:50, moisten with fish dilute again and then the fermentation will have more bacterial activity. My comment here is not a scientific experiment, but just some field observations, perhaps they may help. 

Let me flag off another issue as an off-shoot of this interesting conversation  . If we can prepare a good compost out  of  a raw material having such a exceptionally high C:N ratio ( 500-700:1), then why should we grow green manure crop upto flowering stage or just before the initiation of flowering  only, to facilitate their easy decomposition following their chopping and subsequent ploughing into the field . Why don't , we allow the green manure crops to grow  till crop maturity so there is a much higher biomass production , and subsequently a far higher magnitude of nutrient cycling  could be expected , much to the benefit  of raising the intensity factor to total  nutrient reserve of the soil .     

Dr.Srivastava,Dr.Barlow has provided good lead to proceed with composting of woody plants. One can build upon this with further research.One reason for removing green manure crop at flowering stage is short growing season/ time span available as the farmer has to grow next main crop of rice or sugarcane. Regarding biochar preparation you may refer to the following publication of CRIDA.

Use of biochr for soil health enhancement and green house gas mitigation in India Potential and constraints Ch.Srivasa Rao and others NICRA,CRIDA Hyderabad 2013.

Thanks Dr Rao. Please respond to my  question  posted  couple  of days back, previous to your latest response. Hope , you will love to respond .

I successfully accomplished the task of tree wood reduction by using 10 HP motor fixed to a pulverizer which efficiently powder the wood which in turn is mixed either with biogas spent/digested slurry or with cattle dung in 3:1 proportion by weight ( powder to dung) 

Then what happened to this mixture . Did you use it somewhere? .Did you any response on plant ?. Did you test its final C:N ratio?. Eager get your  response on those issues.

Test crops selected for crop specific vermicompost production were Sesamum, and Banana after harvest of pods and fruits respectively and the products were tested for their efficiency in improving the soil biological status and the crop yields. Both proved as successful in an organic farming practice.exclusively. 

Dr.Srinivasa Reddy ,It is interesting information.You have showed the way for composting of even woody materials and its use in agriculture.My compliments to you.

There are lots of use for coconut as substrate that I know. But not tree, the fruit. It would be a good idea to test some trees.

I already answered this question. I exhort in this context that no plant, be annual or perennial is unsuitable to serve as food material to feed bacteria or fungi, termites, nematodes  or other microbes. It is just a question of particle size, moisture content, temperature and time required for bioconversion. The dried  trees components are downsized artificially using pulverizer in to a powder and mixed with cattle dung fresh in 3:1 ratio by weight, allowed to decompose for a month after which earthworms are introduced to feed on to yield earthworm castings in a month. This is called as vermicomposting and this technique if used for a specific crop like citrus, mango, cotton exclusively, crop specific vermicompost is obtained which can be used for the same crop as it becomes an ideal organic fertilizer considering its composition and constituents. Stated in simple terms, it is nothing but returning back to the tree, what it has given, be considered as symbiotic relation between humans and plants.

Thanks Dr Reddy . This was the very purpose for opening  up the discussion into such length . Large number of perennial trees cross crops , they  are just kept lying without making any attempt to recycle them . There is no  doubt  , they are  comparatively harder  to decompose , but our esteemed colleagues have nicely expressed their views on this very important issue. Hope , it will be usefull to all of us . Thanks everyone for  your so intense participation .

Thank you Mariangela. Can you  elaborate   further on your response . It is very interesting .

We can make a good compost out of dried or dead perennial  trees using some bio-enhancers or cellular de-composers. Always remember anything that comes out from plant is always biodegradable. 

Dear Dr Srivastava, your main objective is reduce the wood waste along with getting some fertility value out of it, below is my attempt at addressing it.

I think your objective can be achieved in two parts - firstly, we need to reduce the large volume of the wood in the form of unproductive trees. As some of the scientists have already suggested, turning it to biochar would be the best option. With >50% conversion rate, you are left with less than half of your wood in the form of biochar which itself is the best C sequestration tool that can positively affect plant nutrient uptake along with synergistic microbial processes.  Secondly, in terms of composting, a co-application of biochar and a fertiliser would be far more beneficial both in terms of labour and value.

We have recently published a book on biochar through CRC press, in case you would like to refer to it. Hope this is helpful. Thank you.

https://www.crcpress.com/Biochar-Production-Characterization-and-Applications/Ok-Uchimiya-Chang-Bolan/p/book/9781482242294

Dear Pranoy , thanks for your excellent feedback , appreciate it . Developing biochar out of dried perennial trees is surely an option to reckon with . Unfortunately , technique of biochar production at farm level is yet not  available , besides  the sckeptism  associated with short term effect of biochar , either in combination with chemical fertilizers or PGPRs. Biochar offers the most stable form of carbon in terms of carbon resilience time in the soil. Effectiveness of biochar is often questioned in alkaline soils as well..? 

Dear Anoop, Response of biochar is dependent on soil (biotic/abiotic parameters), the biochar itself (feedstock, pyrolysis temperature etc) and the sought benefit (nutritive value in your case). These three parameters are interrelated and I have discussed this in the book chapter of the book I suggested. You are right in terms of skepticism around the use of biochar which I have also tried to allude to in that book chapter. I wish your idea could be tried using a pilot study by sending representative wood samples to a biochar production company. Thanks, Pranoy.

Thanks Pranoy for the useful response ..

Yes, we can make a good compost. Our problem is how to regulate the C/N ration of the final product ?