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Tuesday, November 3, 2009: 1:00 PM
Convention Center, Room 334, Third Floor
Abstract:
Biochar is a coined term for the carbonaceous byproduct of various pyrolysis technologies for processing biomass waste into fuels. Biochar has recognized potential value as a form of sequestered carbon and as a beneficial soil amendment. However, since chars are strong adsorbents of organic compounds, a prerequisite to the widescale use of biochar as a soil amendment is a thorough assessment of its effects on bioavailability of agriculturally important chemicals in soil including pesticides, contaminants, and natural plant signaling chemicals (allelochemicals) that play a role in the health of many crops.. Here we report that biochar suppresses the uptake of a soil contaminant by zucchini (Cucurbita pepo), and reduces disease and growth inhibition of asparagus induced by the pathogenic action of allelochemicals.
A soil historically-contaminated with DDE, a metabolite of the legacy pesticide DDT, at 190 ng/g was amended with biochar at 0, 0.1, 1.0, and 10% (m/m) and planted with zucchini. After 28 days growth, the amount of DDE in the tissues was determined. DDE decreased significantly with biochar levels up to 66 and 75% reduction in stems and roots, respectively. Thus, biochar can reduce the bioavailability of aged hydrophobic contaminants in soil.
The second example involves the replant problem in asparagus— asparagus roots produce allelochemicals--saponins and ferulic, coumaric and caffeic acids--that are auto-inhibitory to young asparagus plants, preventing fields from being replanted. In addition, stressed plants are highly susceptible to a crown rot caused by fungal species of Fusarium. The percentage of diseased roots declined and plant weights increased with biochar level. Biochar amendment also reduced the number of Fusarium spp. colonies that grew on agar from plant roots. While binding of allelochemicals remains the working hypothesis, other mechanisms are possible and efforts to decipher them are underway.
A soil historically-contaminated with DDE, a metabolite of the legacy pesticide DDT, at 190 ng/g was amended with biochar at 0, 0.1, 1.0, and 10% (m/m) and planted with zucchini. After 28 days growth, the amount of DDE in the tissues was determined. DDE decreased significantly with biochar levels up to 66 and 75% reduction in stems and roots, respectively. Thus, biochar can reduce the bioavailability of aged hydrophobic contaminants in soil.
The second example involves the replant problem in asparagus— asparagus roots produce allelochemicals--saponins and ferulic, coumaric and caffeic acids--that are auto-inhibitory to young asparagus plants, preventing fields from being replanted. In addition, stressed plants are highly susceptible to a crown rot caused by fungal species of Fusarium. The percentage of diseased roots declined and plant weights increased with biochar level. Biochar amendment also reduced the number of Fusarium spp. colonies that grew on agar from plant roots. While binding of allelochemicals remains the working hypothesis, other mechanisms are possible and efforts to decipher them are underway.