|
Biochar is charcoal used as a soil amendment. Like most charcoal, biochar is made from biomass via pyrolysis. Biochar is under investigation as an approach to carbon sequestration to produce negative carbon dioxide emissions. Biochar thus has the potential to help mitigate climate change via carbon sequestration.〔 〕 Independently, biochar can increase soil fertility of acidic soils (low pH soils), increase agricultural productivity, and provide protection against some foliar and soil-borne diseases.〔(【引用サイトリンク】title= Slash and Char )〕 Furthermore, biochar reduces pressure on forests. Biochar is a stable solid, rich in carbon, and can endure in soil for thousands of years.〔 == History == Pre-Columbian Amazonians are believed to have used biochar to enhance soil productivity. They produced it by smoldering agricultural waste (i.e., covering burning biomass with soil)〔Solomon, Dawit, Johannes Lehmann, Janice Thies, Thorsten Schafer, Biqing Liang, James Kinyangi, Eduardo Neves, James Petersen, Flavio Luizao, and Jan Skjemstad, ''Molecular signature and sources of biochemical recalcitrance of organic carbone in Amazonian Dark Earths'', 71 Geochemica et cosmochemica ACTA 2285, 2286 (2007) ("Amazonian Dark Earths (ADE) are a unique type of soils apparently developed between 500 and 9000 years B.P. through intense anthropogenic activities such as biomass-burning and high-intensity nutrient depositions on pre-Columbian Amerindian settlements that transformed the original soils into Fimic Anthrosols throughout the Brazilian Amazon Basin.") (internal citations omitted)〕 in pits or trenches.〔 To date, scientists have been unable to completely reproduce the beneficial growth properties of ''terra preta''. It is hypothesized that part of the alleged benefits of ''terra preta'' require the biochar to be aged so that it increases the cation exchange capacity of the soil, among other possible effects. In fact, there is no evidence natives made biocahr for soil treatment, but really for transportable fuel charcoal. Abandoned or forgotten charcoal pits left for centuries were eventually reclaimed by the forest. In that time the harsh negative effects of the char (high pH, extreme ash content, salinity) had worn off and turned to positive as the forest soil ecosystem saturated the charcoals with nutrients. ''supra'' note 2 at 386 ("Only aged biochar shows high cation retention, as in Amazonian Dark Earths. At high temperatures (30–70°C), cation retention occurs within a few months. The production method that would attain high CEC in soil in cold climates is not currently known.") (internal citations omitted).〕 European settlers called it ''terra preta de Indio''.〔 "These so-called Terra Preta do Indio (Terra Preta) characterize the settlements of pre-Columbian Indios. In Terra Preta soils large amounts of black C indicate a high and prolonged input of carbonized organic matter probably due to the production of charcoal in hearths, whereas only low amounts of charcoal are added to soils as a result of forest fires and slash-and-burn techniques." (internal citations omitted)〕 Following observations and experiments, a research team working in French Guiana hypothesized that the Amazonian earthworm ''Pontoscolex corethrurus'' was the main agent of fine powdering and incorporation of charcoal debris to the mineral soil. The term “biochar” was coined by Peter Read to describe charcoal used as a soil improvement. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Biochar」の詳細全文を読む スポンサード リンク
|