[Terrapreta] biochar and sugarcane growth (reply to AD Karve)

[Ron Larson]

AD (cc to terrapreta list-members)

Thanks for talking below about sugarcane and char and ash practices in India - a subject I think is very important to the future of all terra preta discussions - as cane/bagasse would seem to be a very ideal early niche market.  I say this because the charrable material is already often being thrown away after being brought to a central location.  I respond in depth to be sure we keep talking about bagasse on this list.

        I raised this bagasse-char opportunity at the recent IAI meeting in Australia.  Before discussing your comments [inserts below], I'd like to update my IAI comments by reporting on new information I gained by stopping in to an Australian sugar mill north of Terrigal after the conference.  I was very surprised to hear that this mill (and one more) is going to a system that incorporates much of what I believe should be done worldwide (short of producing char).  They will be taking ALL of the leaves from the field.  They will operate the power plant year-round, using the leaves and bagasse baled and stored during the harvesting season.  I think the process would be improved by somehow pyrolyzing at least a portion of this material rather than combusting all and of course said so.  Just dropping in un-announced, I was talking to an Engineer from the wrong department - so he could not comment on "terrapreta".  But he was both an engineer and local cane grower and had heard of charcoal in an agricultural context.  A nice guy.  Here's hoping others in Australia (or anywhere) can carry the char-production-from-bagasse idea further.  More along these lines below.

Yesterday, you said:
   I live in India, in Masharashtra state, that produces 40% of the total sugar in India. We have had sugar factories since the early 1930s. All the sugarcane is manually harvested. Typically, a hectare of sugarcane produces about 10 tonnes of dry leaves, so that after the harvest is over, the field is covered with a layer of dry leaves that is often 30 cm thick. Farmers just burn the leaves to clear the field. The charred leaves and ash are then ploughed into the soil. 

      [RWL1:  I think this is true around the world.  But I am guessing that your char component is miniscule.  Anything you can do to ascertain how much char remains in these burning operations in Australia would be a big help.

      Farmers do not grow consecutive crops of sugarcane but always rotate it with other crops. About 50 years ago, there were many farmers who harvested more than 200 tonnes of sugarcane per ha and the average of the state in the 1960s was 100 tonnes per ha. But then yield started declining. The average has now come down to about 80 tonnes per ha and one hardly meets a farmer who harvests more than 150 tonnes per ha. 

      [RWL2:  This sound similar to other reports I have heard.  In this part of Australia the yield is even larger - but only because they have a two year rotation cycle.  Elsewhere, I have been hearing of a 13 month cycle, with about 6 crops in 7 years.  I believe most of the world plants/harvests continuously - with soil productivity staying high through added fertilizers (and accompanying run-off, etc).

      AD - could you clarify how many crops are obtained from one planting of cane in Maharashtra?  It sounds like alternating years of cane and another crop might be the local norm, which would be new information.  How many years of alternative crops before the next one-or-more years of cane?]

  The soil in the sugarcane area is vertisol, having a pH ranging from 8.2 to 8.7. I am not saying that incorporation of char and ash caused decline in sugarcane yield. There might be entirely other reasons for it, but after reading that biochar might not work in alkaline soils, one is tempted to come to this conclusion.

     [RWL3:   Your are describing the direct opposite (slash and burn) of what seems to have occurred in Brazil (slash and char).   I think there is likely to have been so little char going into the Indian cane soil that the blame for declining productivity is more appropriately placed on the ash.  Huge amounts of nutrients are taken out with the bagasse and the small amount returned in the 10% leaf burning is receiving little aid from the small char apt to end up there.  

      Better than anyone I know, your ability to pyrolyze in the field suggests the need to try some experiments - and really put at least the leaf char back into the local soil.  Better yet, it should be relatively easy to pyrolyze the bagasse - and (experimentally) place back into the ground various ratios of what was taken out.  My prediction is that the more charcoal (no ash) placed back into the soil, the better will be the production in the next year or two.  Here's hoping you can find some willing land owners and enough research dollars to carry out the experiment which you are uniquely qualified to do - even if only on sugar cane plots much smaller than a hectare.  Again - thanks for keeping the sugar cane opportunities alive as a discussion topic.  I know of no other crop anywhere in the world which is so wasteful of a great resource.]

      Ron

      

   

  Yours 

  A.D.Karve



------------------------------------------------------------------------------


  _______________________________________________
  Terrapreta mailing list
  Terrapreta at bioenergylists.org
  http://tech.groups.yahoo.com/group/biochar/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: /pipermail/terrapreta_bioenergylists.org/attachments/20070518/60ece50b/attachment.html