Updates:
Nov. 23, 2010
About 100 kg of greenhouse waste biochar has been produced at 450oC, and is already being tested in tomato plants and strawberry.
iBRN had its first annual Char-B-Q today, and welcomed 3 new students to the team.
A new publication has been posted today to Environmental Science & Technology
Silber, A., Levkovitch, I., Graber, E.R. 2010. pH-dependent mineral release and surface properties of cornstraw biochar: Agronomic implications. Environ. Sci. Technol. ASAP. http://pubs.acs.org/doi/pdf/10.1021/es101283d
Abstract: Surface charge and pH-dependent nutrient release properties of cornstraw biochar were examined to elucidate its potential agronomic benefits. Kinetics of element release was characterized by rapid H+ consumption and rapid, pH-dependent P, Ca, and Mg release, followed by zero-order H+ consumption and mineral dissolution reactions. Initial K release was not pH-dependent, nor was it followed by a zero-order reaction at any pH. Rapid and constant rate P releases were significant, having the potential to substitute substantial proportions of P fertilizer. K releases were also significant and may replace conventional K fertilizers, however, not long term plant demand. The cation exchange capacity (CEC) of the biochar leached with a mild acidic solution increased linearly from 179 to 888 mmolc kg C-1 over a pH range of 4 to 8, while the anion exchange capacity of 154 mmolc kg C-1 was constant over the same pH range. Since native soil organic constituents have much higher CEC values (average 2800 mmolc kg C-1 at pH 7), improved soil fertility as a result of enhanced cation retention by the biochar probably will be favorable only in sandy and low organic matter soils, unless surface oxidation during aging significantly increases its CEC.
Sept. 15, 2010
Our pyrolysis unit (the BEK, from All Power Labs) is up and working, and we've started generating biochar in batch and continuous modes.
2 new publications are out, one in Phytopathology and one in Plant and Soil:
Elad, Y., Rav David, D., Meller Harel, Y., Borenshtein, M. , Ben Kalifa H., Silber, A., and Graber, E.R. (2010) Induction of systemic resistance in plants by biochar, a soil-applied carbon sequestering agent. Phytopathology 100, 913-921. http://apsjournals.apsnet.org/doi/pdfplus/10.1094/PHYTO-100-9-0913
Abstract: Biochar is the solid co-product of biomass pyrolysis, a technique used for carbon-negative production of second generation biofuels. The biochar can be applied as a soil amendment, where it permanently sequesters carbon from the atmosphere, as well as improves soil tilth, nutrient retention, and crop productivity. In addition to its other benefits in soil, we found that soil-applied biochar induces systemic resistance to the foliar fungal pathogens Botrytis cinerea (gray mold) and Leveillula taurica (powdery mildew) on pepper and tomato and to the broad mite pest (Polyphagotarsonemus latus Banks) on pepper. Levels of 1-5% biochar in a soil and a coconut fiber:tuff potting medium were found to be significantly effective at suppressing both diseases in leaves of different ages. In long term tests (105 days), pepper powdery mildew was significantly less severe in the biochar treated plants than in the plants from the unamended controls, although during the final 25 days, the rate of disease development in the treatments and controls was similar. Possible biochar-related elicitors of systemic induced resistance are discussed.
Graber, E.R., Meller Harel, Y., Kolton, M., Cytryn, E., Silber, A., Rav David, D., Tsechansky, L., Borenshtein, M., Elad, Y. (2010) Biochar impact on development and productivity of pepper and tomato grown in fertigated soilless media. Plant and Soil (online). http://www.springerlink.com/content/45g624l441843335/fulltext.pdf
Abstract: The impact of additions (1-5% by weight) of a nutrient-poor, wood-derived biochar on pepper (Capsicum annuum L.) and tomato (Lycopersicum esculentum Mill.) plant development and productivity in a coconut fiber:tuff growing mix under optimal fertigation conditions was examined. Pepper plant development in the biochar-treated pots was significantly enhanced as compared with the unamended controls. This was reflected by a system-wide increase in most measured plant parameters: leaf area, canopy dry weight, number of nodes, and yields of buds, flowers and fruit. In addition to the observed increases in plant growth and productivity, the rhizosphere of biochar-amended pepper plants had significantly greater abundances of culturable microbes belonging to prominent soil-associated groups. Phylogenetic characterization of unique bacterial isolates based on 16S rRNA gene analysis demonstrated that of the 20 unique identified isolates from roots and bulk soil from the char-amended growing mixes, 16 were affiliated with previously described plant growth promoting and/or biocontrol agents. In tomato, biochar treatments positively enhanced plant height and leaf size, but had no effect on flower and fruit yield. The positive impacts of biochar on plant response were not due to direct or indirect effects on plant nutrition, as there were no differences between control and treatments in leaf nutrient content. Nor did biochar affect the field capacity of the soilless mixture. A number of organic compounds belonging to various chemical classes, including n-alkanoic acids, hydroxy and acetoxy acids, benzoic acids, diols, triols, and phenols were identified in organic solvent extracts of the biochar. We conjecture two related alternatives to explain the improved plant performance under biochar treatment: (i) the biochar stimulated shifts in microbial populations towards beneficial plant growth promoting rhizobacteria or fungi, due to either chemical or physical attributes of the biochar; or (ii) low doses of biochar chemicals, many of which are phytotoxic or biocidal at high concentrations, stimulated plant growth at low doses (hormesis).
