[Stoves] Biochar as an Agricultural Tool Was: Re: [biochar] allAfrica.com: Africa: Biochar -Unfulfilled Promises in Cameroon

Sat Dec 31 10:52:15 CST 2011

Dear All

Biochar is not a panacea, contrary to what its enthusiastic supporters infer. It works, and is beneficial in some circumstances, and it fails to be beneficial in others. Charcoal that is used in Agriculture as a soil amendment is called "Biochar", yet it has taken on a life of its own, as a "Climate Improvement Tool". The "Climate Improvement People" seem to assume that biochar is beneficial to agriculture, and don't seem to have much interest in whether or not biochar is an economically sound investment as an "agricultural additive."

What would be vital to know are the circumstances where it is sensible to consider the use of biochar to improve agricultural productivity. Agricultural Science can analyze a soil and say, for example: "This soil needs 1.0 tons of N  and 3.5 tons of Ca per acre to turn it into a good garden soil." As far as I know, there is no way to make a sound and rational recommendation on how much biochar to add per acre. It is totally irresponsible, in my opinion, to recommend a general addition of (say) 10 tonnes per hectare; some soils may attain optimal benefit with 1 tonne/Ha, while other soils may require 20 tonnes per Ha

Some people say that "Biochar improves moisture retention characteristics of soil."  Just how much moisture can biochar retain? Are there better ways to retain moisture in the soil? For example, a kG of peat can retain about 7 kG of water. Biochar is notoriously difficult to wet, and it is thus difficult to get it to absorb or retain moisture. Perhaps the best way to retain moisture is to simply add the organic matter,  from which biochar could be made, directly to the soil? 

We are told that "Biochar is better than organic matter because it lasts 1,000+ years in the soil." Sure! Because it does not provide feed for soil organisms! A key concept in Organic Agriculture is "Feed the soil, and the plants can look after themselves.". Biochar does not "feed the soil."

We are told that "Biochar is a haven for soil microbes." Well, in many cases, any microbes that can enter the char pores would be smothered by the microbes that would cover the outer surface of the individual charcoal grain. 

We are shown really nice photos of how roots head for charcoal lumps, and are told "See how charcoal promotes plant development!" The reality may be that the charcoal robs the nutrients from adjacent soil and concentrates it within the charcoal. The kid looking for candy goes into the candy store, rather than looking on the pavement outside it. 

We are also told that "Biochar is organic matter." If it can't feed soil microbes, it is not organic matter.

The only thing I know for sure about biochar is that it can sequester carbon. Does anyone know specifically how and why biochar is beneficial to agriculture? Does anyone know the "soil circumstances" when and how to apply biochar to a soil to improve upon or eliminate a specific soil deficiency? 

A Farmer can take a soil sample, have it analysed, and competent Soil Scientists can tell him exactly what he should add to the soil to improve it. Are there ANY "soil circumstances" where a biochar addition would be the best additive to cure a soil deficiency?

If so, what are they?

Now, biochar may be effective in curing a particular condition, but there may be more economic alternatives for accomplishing the same end result. Naturally, the sensible Farmer will want to employ them rather than biochar, because he saves money.

The bottom line question seems to be: Are there any circumstances where biochar additions are the best tool for the Farmer to use to improve productivity and reduce costs?

If there are, then I would suggest that they should be clearly identified, as a way to expand the use of biochar, and to benefit the Farmer.

Best wishes,

Kevin Chisholm

  ----- Original Message ----- 
  From: Alex English 
  To: Discussion of biomass cooking stoves 
  Sent: Saturday, December 31, 2011 10:35 AM
  Subject: Re: [Stoves] [biochar] allAfrica.com: Africa: Biochar -Unfulfilled Promises in Cameroon

  Dear Anand,
  It is well documented how new drugs are often compared in trials to treatments that are not the best current treatment. Thus the not so surprising favorable results. 

  Physicist Richard Feynman would ask to see the data, so he could draw his own conclusions, which could differ from the primary author. 
  "Science is the belief in the ignorance of experts" 

  What then is 'peer review'?

  So much of what we read about biochar sounds like a woefully inadequate recipe for curry. Just add spices.  Without differentiating char characteristics and the conditions of treatment soils, all we can conclude is further research is required, or go back and do it right. If you multiply those variables you can put a high quantity on 'expert ignorance'. Add a pinch of time span,and biology, then good and bad results become curiosities. Terra Preta  may be a fine wine now but what was it back then. 

  Unburned Char can have value right now. Potting mix, sorption of nasties, crayons, even as insulation under hydronic heating lines. Physics and chemistry are quick. Biology is a chronic research pain that delights and confounds. 

  Repeatedly we see reference to biochar being beneficial to 'highly weathered" tropical soils. Would you characterize any of the soils you added charcoal to as being "highly weathered"?  

  Regards,
  Alex

  On 31/12/2011 12:14 AM, Anand Karve wrote: 
    Dear Kevin, Crispin and Ron,
    I have been conducting experiments, off and on, for almost a decade on effect of charcoal applied to the soil. Most of the work consisted of very preliminary experiments, just to find out if application of charcoal gave positive results. I would have started a systematic study, if the preliminary results had indicated that this was a useful technology. I never got beyond the stage of preliminary experiments, because they did not reveal to me any beneficial effects on crop yield. I never reported the results in any formal publication, because the experiments were of a very preliminary nature, not conducted in statistically approved designs. Secondly, I want to say that It is generally the tendency among scientists to cite references that support one's findings. So picking and choosing of evidence that supports one's point of view is quite common in scientific publications.
    Yours
    A.D.Karve 

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