Biochar

A large pile of biochar
A pile of biochar
Biochar mixture ready for soil application
Biochar mixture ready for soil application

Biochar is charcoal, sometimes modified, that is intended for organic use, as in soil. It is the lightweight black remnants, consisting of carbon and ashes, remaining after the pyrolysis of biomass, and is a form of charcoal.[1] Biochar is defined by the International Biochar Initiative as the "solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment".[2]

Biochar is mainly used in soils to increase soil aeration, reduce soil emissions of greenhouse gases,[3] reduce nutrient leaching and reduce soil acidity[4] and can increase soil water content in coarse soils.[5] Biochar application may increase soil fertility and agricultural productivity.[4] Biochar soil amendments, when applied at excessive rates or with unsuitable soil type and biochar feedstock combinations, also have the potential for negative effects, including harming soil biota, reducing available water content, altering soil pH and increasing salinity.[6]

Beyond soil application, biochar can be used for slash-and-char farming, for water retention in soil, and as an additive for animal fodder. There is an increasing focus on the potential role of biochar application in global climate change mitigation. Due to its refractory stability, biochar can stay in soils or other environments for thousands of years.[7] This has given rise to the concept of Biochar Carbon Removal, i.e. carbon sequestration in the form of biochar.[7] Carbon removal can be achieved when high-quality biochar is applied to soils, or added as a substitute material to construction materials such as concrete and tar.

  1. ^ Khedulkar, Akhil Pradiprao; Dang, Van Dien; Thamilselvan, Annadurai; Doong, Ruey-an; Pandit, Bidhan (30 January 2024). "Sustainable high-energy supercapacitors: Metal oxide-agricultural waste biochar composites paving the way for a greener future". Journal of Energy Storage. 77: 109723. Bibcode:2024JEnSt..7709723K. doi:10.1016/j.est.2023.109723. ISSN 2352-152X.
  2. ^ "Standardized production definition and product testing guidelines for biochar that is used in soil" (PDF). International Biochar Initiative. 23 November 2015. Archived (PDF) from the original on 25 February 2019.
  3. ^ Wang, Yuchen; Gu, Jiayu; Ni, Junjun (1 December 2023). "Influence of biochar on soil air permeability and greenhouse gas emissions in vegetated soil: A review". Biogeotechnics. 1 (4): 100040. Bibcode:2023Biogt...100040W. doi:10.1016/j.bgtech.2023.100040. ISSN 2949-9291.
  4. ^ a b Dai, Zhongmin; Zhang, Xiaojie; Tang, C.; Muhammad, Niaz; Wu, Jianjun; Brookes, Philip C.; Xu, Jianming (1 March 2017). "Potential role of biochars in decreasing soil acidification - A critical review". The Science of the Total Environment. 581–582: 601–611. Bibcode:2017ScTEn.581..601D. doi:10.1016/j.scitotenv.2016.12.169. ISSN 1879-1026. PMID 28063658.
  5. ^ Razzaghi, Fatemeh; Obour, Peter Bilson; Arthur, Emmanuel (1 March 2020). "Does biochar improve soil water retention? A systematic review and meta-analysis". Geoderma. 361: 114055. doi:10.1016/j.geoderma.2019.114055. ISSN 0016-7061.
  6. ^ Brtnicky, Martin; Datta, Rahul; Holatko, Jiri; Bielska, Lucie; Gusiatin, Zygmunt M.; Kucerik, Jiri; Hammerschmiedt, Tereza; Danish, Subhan; Radziemska, Maja; Mravcova, Ludmila; Fahad, Shah; Kintl, Antonin; Sudoma, Marek; Ahmed, Niaz; Pecina, Vaclav (20 November 2021). "A critical review of the possible adverse effects of biochar in the soil environment". Science of the Total Environment. 796: 148756. Bibcode:2021ScTEn.79648756B. doi:10.1016/j.scitotenv.2021.148756. ISSN 0048-9697. PMID 34273836.
  7. ^ a b Lean, Geoffrey (7 December 2008). "Ancient skills 'could reverse global warming'". The Independent. Archived from the original on 13 September 2011. Retrieved 1 October 2011.