Thanks Kevin, for your answer.
I am quite aware of most of these factors and of their interdependance. That´ s why I ask for practical experience. Chemistry, soil science and technology are very interesting, but they cannot replace the practical, hands on experiments with varying conditions. Therefore I ask again if anyone has practical experience with biochar application on carbonate derivated soils with some loess mixed. Thanks again and have a nice WE Rolf Am Donnerstag, 13. Dezember 2012, 15:02:18 schrieben Sie: > Dear Rolf > ----- Original Message ----- > From: Energies Naturals C.B. > To: Discussion of biomass cooking stoves > Sent: Thursday, December 13, 2012 4:18 AM > Subject: [Stoves] biochar in basic soils? > > > Hallo all, > > this is a question I have asked quite often, but perhaps never on the > list . > > Whenever I read about the benefits of biochar, it is almost always in > relation with distinctively acid soils. > > Does anyone know the effect of biochar, itself beeing mostly basic, on > already basic soils ? > > # I would suggest that the reason why your question has not been answered > already is that it is much more complex than it first appears. # Firstly, > the method of testing biochar for pH is very important. If a given biochar > is added to distilled water, and a pH reading is taken, this pH reading > will probably not be a meaningful indicatior of the degree to which a > biochar will modify soil pH. For one thing, there may be no indication of > the quantity of biochar added per litre of water used in teh pH test. > > # Secondly, the amount of biochar added to a given soil is very > important. Clearly, the impact of 1 Tonne per HA will be less than an > addition of 10 tonnes per HA. > > # Thirdly, the nature of the soil to which the biochar is added will heve > a large effect on the pH change. A given addition of biochar to a sandy > soil will have a very much larger effect on pH than would the same rate of > addition have on a clay soil with a large buffering effect. > > # Fourthly, the species of material responsible for the pH increase is > very important. If a soil was basic because of relatively high calcium, > but was deficient in potassium, a biochar with a high potassium content > could result in a significant benefit to plant growth, greater than the > detriment associated with a rise in pH. > > # Fifthly, the species of biomass and its preparation prior to conversion > to biochar can be very important. Biochar made from fresh grass and leaves > would be expected to have a higher pH than would biochar made from leaves > and grasses that were weathered. Biochar made from de-barked wood would be > expected to have a higher pH than would biochar made from de-barked wood. > > Sixthly, the process used to manufacture biochar could have a significant > effect on its pH. A process with a high yield of biochar may have less > "free ash" available for changing the apparent pH of the char. > > Seventhly, post-processing of a biochar can have an influence on pH. > Biochar that is screened to remove ash would be expected to have a lower > pH than would biochar that was not screened for ash removal. similarily, > such screenings would be expected to have a significantly higher pH than > would the coarser char particles remaining on the screen. > > There are likely other important factors impacting on the pH effects that > biochar additions could bring to a given soil. > > Best wishes, > > Kevin > > > Rolf > > > > > > > > Am 13.12.2012 05:10, schrieb Kevin: > Dear Tom > ----- Original Message ----- > From: Tom Miles > To: [email protected] ; [email protected] ; > 'Discussion of biomass cooking stoves' Sent: Wednesday, December 12, 2012 > 2:18 AM > Subject: Re: [Stoves] [biochar-policy] Re: Equipment required for > testingstoves > > > Charcoal burns in direct contact with air well above 600 C so any > fire at the charcoal stage would be above 500-600C. > > > > # There are two issues here: > > 1: The temperature at which charcoal burns > > 2: The average temperature experienced by the charcoal remaining > after it was produced. > > Certainly, charcoal can burn at temperatures well above 600C in air. > Surface temperatures of burning char can be very different than the core > temperature. Consider a flash fire, with high surface temperatures for a > short time. Core temperatures of the wood or char remaining can be very > much lower. This is a very complex heat transfer problem... unsteady state > three dimensional heat transfer to bodies of irregular shape, with change > in phase. What is important is the properties of the "unburned charcoal" > remaining for potential use as biochar. > > > > Higher temperature oxidized chars have great adsorption properties. > They compost readily. Great way to make terra preta. > > > > # Certainly, such "designer chars" could have very superior > properties, but at greater cost. The "bottom line" for the Farmer or > Grower is the "Benefit/Cost Ratio." Additionally, there may be special > soil conditions that such "designer chars" can handle better than "regular > biochar" that works adequately well for most common soil conditions. > > > > Best wishes, > > > > Kevin > > > > Tom > > From: [email protected] > [mailto:[email protected]] On Behalf Of Kevin Sent: Tuesday, > December 11, 2012 8:18 PM > To: [email protected]; Discussion of biomass cooking stoves; > biochar-policy Cc: Alex English; Tom Miles > Subject: [biochar-policy] Re: [Stoves] Equipment required for testing > stoves > > > > > > > > Dear Ron > > ----- Original Message ----- > > From: [email protected] > > To: Discussion of biomass cooking stoves ; biochar-policy > > Cc: Alex English ; Kevin Chisholm ; Tom Miles > > Sent: Tuesday, December 11, 2012 2:09 AM > > Subject: Re: [Stoves] Equipment required for testing stoves > > > > Lists (adding biochar-policy also), Kevin, Alex, Tom (who I add, > because he speaks Portuguese and might have caught an answer when we were > in Manaus a few years ago) > > See below > > From: "Kevin" <[email protected]> > To: "Discussion of biomass cooking stoves" > <[email protected]>, "Alex English" <[email protected]> > Cc: "Discussion of biomass cooking stoves" > <[email protected]> Sent: Monday, December 10, 2012 8:24:34 > PM > Subject: Re: [Stoves] Equipment required for testing stoves > > > > Dear Ron > > > > Would you agree that the Amazonians made Terra Preta with low > temperature char? [RWL1: I think others may have an answer - maybe based > on spectroscopy. I will start looking but don't know that field well > enough to know what others may have concluded about these ancient soils. > I fear that 500 years (minimum) in soil may hide the initial character > that we can readily see in a University setting. I know from being in > several Amazonian biochar "pits" that it is pretty hard to find a piece > big enough to test. I think it entirely possible that char left over from > simple three-stone fires could have been made at 500-600 C (or higher). > Would you call those temperatures high or low?] > > > > # KC1: Obviously, I am speculating, but I would speculate that > Terra Preta was made with charcoal from a number of sources: > > 1: Char residue remaining after charring or burning of "wood waste > from initial jungle clearing. > > 2: Char residue remaining from charring or burning of agricultural > waste and weeds > > 3: Char and ash residue from cooking fires and possibly smudge pots > > 4: Organic fertilizer supplements, from humanure, composted food > scraps, and probably dredgings from oxbow lakes. > > I would consider 500-600 C to be a "low temperature char." I > haven't seen any references to the existence of bellows technology in > ancient Amazonia, that would be necessary to produce significantly higher > temperatures. > > It is likely that the Amazonian Terrapretians would have quickly > noticed if such low temperature char additions to their agricultural > practises were causing poor results. If that was the case, they likely > would have taken steps to avoid application of char to fields. They would > be looking for short term benefits or harm. Given that they used char on a > widespread basis, and that it was basically low temperature char, it would > thus seem that Terra Preta worked with low temperature char, and it worked > relatively quickly, not requiring an aging period of several years. > > > > > If so, are there any test results to show that an "intermediate > temperature char" would give better results than the "low temperature > char?" [RWL2: I think that people like Dr. Johannes Lehmann and Evelyn > Krull may be getting to an answer for some specific soil and species. I > keep looking for it. My note below to Alex was to make it easier for users > to know what is being used Some of my favorite biochar scientists like > Drs. Julie Major and Christoph Steiner were forced to use char bought off > the side of a remote Amazonian road. I haven't seen any data emphasizing > tests with a range of temperatures. Drs. Stephen Joseph (low) and Hugh > McLaughlin (high) recommend different temperature regimes.] > > > > #KC2: Is it perhaps likely that "basic low temperature biochar" is > good for general agricultural applications, but that intermediate and high > temperature chars may be better for addressing special agricultural > problems. > > > > I seem to recall that "high temperature char" and/or "activated > char" gives inferior results in a biochar application. [RWL3: How about > giving a cite for that?] > > > > #KC3: Unfortunately, I cannot point to a specific cite. > > Does this impression make sense to you? > [RWL4: No - certainly not as a universal truth/] > > > > #KC4: Universal truths are scarce and hard to find. :-) If you put > yourself in the circumstances of an Amazonian Terrapretian of 3,000 years > ago, what would you do differently? > > If so, is there a "preferred char making temperature range"? > [RWL5: I am sure that it depends a lot on the intended > recipient soil - and probably on the plant species. #KC5:1 Certainly! > Jungle woods can vary in density from balsa at about 10 lb/cubic foot, to > Lignum Vitae, at about 68 pounds per cubic foot. > > > > My focus in this exchange below with Alex is to give soil > researchers and stove users a better idea of even getting close to knowing > what char-T they are using. > > #KC5:2 Char making temperature is easy to determine. It should thus > be very easy to determine the importance, or lack thereof, of char making > temperature. It would be very good to know this, to reduce variables in a > test analysis. > > > > There is a good bit of information out there relating pH to > production temperature - but pH also depends on fuel size and ash content > and pH changes over time. Who knows what else leads to a "preference"? > And we also hear from Dr. Spokas that what happens after char production > is maybe as much or more important. I think it is absolutely amazing > that we hear so many good reports (and few bad reports) when we know so > little even about the char-production temperature - and even the wood > species, etc, etc, etc. Ron] > > > > #KC: With that many "good reports" and so few "bad reports", and > with so many char variables, this would tend to downplay the importance of > char variables. The "bad reports", presuming that they were competently > done, could provide very important insights into what works, and what > doesn't. > > Best wishes, > > > > Kevin > > > > Best wishes, > > > > Kevin > > ----- Original Message ----- > > From: [email protected] > > To: Alex English > > Cc: Discussion of biomass cooking stoves > > Sent: Monday, December 10, 2012 9:46 PM > > Subject: Re: [Stoves] Equipment required for testing stoves > > > > Alex: > > Thanks: > > I see only a few remaining questions related to the > thermocouples. My interest is only in being able to report to the soil > scientists the temperature at which the char was produced. > > Q1. I think we should be able to say that a time average of > a central thermocouple measurement showing a slight drop over time of the > highest numbers is a pretty good estimate - that could be reproduced for > "any" similar "flaming pyrolysis" approacd. The properties (pH, surface > areas, labile component, etc) of such char should be compared (a Master's > thesis?) with char produced via other means. I think Nat Mulcahy's > non-flaming pyrolysis approach can produce varying temperature char. An > all-electric heating approach in any oxygen-free environment , operated at > different temperature should also be used to compare the char properties > with those from stoves. Maybe that data is already out there?? > > Q2. I think there could be some influence of the initial fuel > moisture content. Do you (anyone) have an opinion on that? I am trying > to avoid having to always measure temperatures, but still be able to give > an indication of the "likely" char temperature, by knowing how long a > specific volume or weight of fuel lasted. > > Q3. I wonder if the char temperature as measured by a > thermocouple system like yours would also be a function of the fuel itself > (species, characteristic size, shape, etc.) > > Q4. I am pretty sure that the top and bottom char will be > significantly different in a typical cooking cycle, where a very high > flame temperature is desired at first (affecting only the top part of the > fuel load), and then a much lower temperature desired later (affecting > only the lowest portion of the fuel load). My question, for anyone, is > whether an average temperature is at all valuable, if the average > (obtained from the total duration of the pyrolysis) covered a wide range > of production temperatures. Actually I have heard so many different > opinions on the best production temperature - maybe a mixture of char > temperatures might be an advantage. Thoughts? > > > Ron > > > > From: "Alex English" <[email protected]> > To: [email protected], "Discussion of biomass cooking > stoves" <[email protected]> Sent: Monday, December 10, 2012 > 4:38:56 AM > Subject: Re: [Stoves] Equipment required for testing stoves > > Ron, > > On 09/12/2012 8:33 PM, [email protected] wrote: > > Alex etal > > Thanks for the cite. I think I understand most of the plot - > which was of amazing duration!. I am especially amazed at how uniform > (and high) the flame temperature was in the late time plot, even as the > other plots were dropping. > > It is a very steady gas producer. Conditions are constant except > for the distance and path composition between the pyrolysis front and the > burner. If it can be done over 100cm then why not 200 or 300. > > > > a. Since you have this one from 2000, you probably have > quite a few more - from which I/we might extract a good bit more > information/ Any other similar plots around that you can post? > > No I don't. > > > > > b. I am surprised that the "pyrolysis gas temperature" was > so much lower than the temperature of the char. Where was the probe for > this measurement - and had there been some mixing of secondary air at this > point? > > No mixing of secondary air at that point. That occurs in and > above in a 5cm burner mixing pipe. The tmperature difference is largely > due to the nature of unshielded thermocouples in gas.For the most part > thermocouples radiate away heat according to the temperatures of the > surfaces that make up the sphere around them. A thermocouple buried in the > pellets that are all carbonizing at 700C will give a fairly accurate > measurement. A thermocouple in the gas above the top of the pellet bed > will radiate to the pellet bed and, in this case the uninsulated container > walls. The more that pellet bed shrinks the larger the portion of the > radiant sphere that is the cool container walls. The larger the > thermocouple, the greater the radiant cooling , the lower the measurement. > The higher the temperature the greater the radiant loss, to the forth > power. All the gas is also radiating and convecting heat to the container > walls. So there are two reasons for a slow drop in gas temperature, and > one reason for not trusting either. The same holds true for the absolute > value of post combustion measurement. > > There are gas-aspirated pyrometers which shield a thermocouple > with ceramic layers that approach gas temperatures and give better > numbers. We will soon be using an 10 footer to probe the chain grate > stoker gasses in carbonizer- pyrolysis-gasifier mode. > > Grate fun. > > > > > c. What is the present disposition of this equipment? > > Its in the recoverable bone yard. I should have shown it to > Crispin when he was here.....or perhaps not:) > > Alex > > > > > Nice work > > Ron > > > > > > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylis > ts.org > > for more Biomass Cooking Stoves, News and Information see our > web site: http://www.bioenergylists.org/ > > > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylis > ts.org > > for more Biomass Cooking Stoves, News and Information see our web > site: http://www.bioenergylists.org/ > > __._,_.___ > > Reply via web post > Reply to sender > Reply to group > Start a New Topic > Messages in this topic (2) > > > Recent Activity: > > · New Members 1 > > Visit Your Group > > > > Switch to: Text-Only, Daily Digest • Unsubscribe • Terms of Use • > Send us Feedback > > . > > > > __,_._,___ > > > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylis > ts.org > > for more Biomass Cooking Stoves, News and Information see our web > site: http://www.bioenergylists.org/ > > > > > > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylist > s.org > > for more Biomass Cooking Stoves, News and Information see our web site: > http://www.bioenergylists.org/ > > > > > > --------------------------------------------------------------------------- > --- > > > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylis > ts.org > > for more Biomass Cooking Stoves, News and Information see our web site: > http://www.bioenergylists.org/ _______________________________________________ Stoves mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org for more Biomass Cooking Stoves, News and Information see our web site: http://www.bioenergylists.org/
