Dear Paul,
The way I look at it; Biochar is not needed by the plant anymore than peat moss, perlite, sand, lime, gypsum etc. These are all materials used to change the texture of the soil. Better drainage, hold more water, make water more available, adjust pH that changes availability of nutrients, added porosity, add microbes that regulate the nutrients etc. If the biochar product adjusts one of these components to make the required constituents (water, nutrients, temperature etc) more optimum for the plant you will see a benefit. A lot of silica (as in rice hulls) may very well be the component that makes the change and the carbon fraction has nothing to do with it. Or it could all be from the carbon fraction or mixture of both. IMO it is important to determine the condition change that has created the increase in plant response. And the constituent of the biochar that has done it. Then we can determine the biochar quality that should be used on that specific site. But I think we can agree that it's the carbon component we regard as important when talking biochar. If it's the silica in rice hulls making the difference we could just add something like sand. Being carbon as the important fraction biochar quality should be rated based on the carbon component. Not only carbon concentration but also the carbon structure (or we could just as well add organic matter). Carbon comes in a range of biological activity. Very reactive like green grass, sugars, oils, vegetative materials. Semi-reactive materials like wood chips, stabilized compost, biosolids and organics from aeration ponds, finished septic systems etc and very stabilized like plastic, biochar. Available carbon increases microbes. That in turn uses a lot of oxygen making soils anaerobic creating lots of problems. The reason we compost and have septic systems before letting high reactive organics into the environment. Because biochar claim to have a very stabilized carbon (non-available to microbes and oxidation) we need to measure to the degree the carbon is stabilized in addition to the concentration to rate and compare biochar products. Rice biochar has low carbon (not good) but likely high stability (good). And a unique structure, that in the right locations and soil type, could make all the difference. It's the test methods that work best to determine the carbon concentration and properties that we need to sort out. Not an easy task thanks to people wanting to use coal testing methods for biochar. We need our own methods manual. Regards Frank Frank Shields Control Laboratories, Inc. 42 Hangar Way Watsonville, CA 95076 (831) 724-5422 tel (831) 724-3188 fax [email protected] www.compostlab.com _____ From: [email protected] [mailto:[email protected]] On Behalf Of Crispin Pemberton-Pigott Sent: Thursday, October 27, 2011 6:56 AM To: 'Discussion of biomass cooking stoves' Subject: Re: [Stoves] [biochar-production] Re: Stoves Digest, Vol 14,Issue 17 Dear Paul Do you know if the char has been characterised well, or is it from the smoky stacks you described earlier? Thanks Crispin ++++++ Frank, Rice hulls biochar makes as excellent soil amendment, as numerous test have shown. Yields on rice, water spinach and other plants have increased roughly 3-fold in the trials that were done in Vietnam and Cambodia. If it is not the best biochar, I would be truly exciting to find something better. Paul Olivier
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