Slash-and-char

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Slash-and-char is an alternative to slash-and-burn that has a lesser effect on the environment. It is the practice of charring the biomass resulting from the slashing, instead of burning it. Due to incomplete combustion (pyrolysis) the resulting residue matter charcoal can be utilized as biochar to improve the soil fertility. [1] [2]

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Charcoal production under an earth cover Meiler 5.JPG
Charcoal production under an earth cover

In that context, charcoal can be made by numerous and varied methods. The simplest, used historically in charcoal production, involves burning a pile of biomass by lighting it on the top (known as "top down burn" or "conservation burn" [3] [4] ) or an earth cover on the pile of wood, with strategically placed vents. A more sophisticated modern method involves equipment that recuperates and processes strictly all exhaust gases into pyroligneous acid and syngas.

Slash-and-char offers benefits to the environment when compared to slash-and-burn. [5]

It results in the creation of biochar, which can then be mixed with biomass such as crop residues, food waste, or manure, and buried in the soil to bring about the formation of terra preta. Terra preta is one of the richest soils on the planet – and the only one known to regenerate itself.[ citation needed ]

It moreover sequesters considerable quantities of carbon in the safest and most beneficial fashion, as opposite to the negative effects of the slash-and-burn. Switching to slash-and-char can sequester up to 50% of the carbon in a highly stable form. [5] The nascent carbon trading market that sponsors CO2 sequestration projects, could therefore help supplement the farmers' income while supporting a decrease in the pace of deforestation and the development of a more sustainable agriculture.

See also

Related Research Articles

<span class="mw-page-title-main">Pyrolysis</span> Thermal decomposition of materials at elevated temperatures in an inert atmosphere

The pyrolysis process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. The word is coined from the Greek-derived elements pyro "fire", "heat", "fever" and lysis "separating".

<span class="mw-page-title-main">Slash-and-burn</span> Agricultural practice

Slash-and-burn agriculture is a farming method that involves the cutting and burning of plants in a forest or woodland to create a field called a swidden. The method begins by cutting down the trees and woody plants in an area. The downed vegetation, or "slash", is then left to dry, usually right before the rainiest part of the year. Then, the biomass is burned, resulting in a nutrient-rich layer of ash which makes the soil fertile, as well as temporarily eliminating weed and pest species. After about three to five years, the plot's productivity decreases due to depletion of nutrients along with weed and pest invasion, causing the farmers to abandon the field and move to a new area. The time it takes for a swidden to recover depends on the location and can be as little as five years to more than twenty years, after which the plot can be slashed and burned again, repeating the cycle. In Bangladesh and India, the practice is known as jhum or jhoom.

<span class="mw-page-title-main">Solid fuel</span>

Solid fuel refers to various forms of solid material that can be burnt to release energy, providing heat and light through the process of combustion. Solid fuels can be contrasted with liquid fuels and gaseous fuels. Common examples of solid fuels include wood, charcoal, peat, coal, hexamine fuel tablets, dry dung, wood pellets, corn, wheat, rye, and other grains. Solid fuels are extensively used in rocketry as solid propellants. Solid fuels have been used throughout human history to create fire and solid fuel is still in widespread use throughout the world in the present day.

<span class="mw-page-title-main">Wood fuel</span> Wood used as fuel for combustion

Wood fuel is a fuel such as firewood, charcoal, chips, sheets, pellets, and sawdust. The particular form used depends upon factors such as source, quantity, quality and application. In many areas, wood is the most easily available form of fuel, requiring no tools in the case of picking up dead wood, or few tools, although as in any industry, specialized tools, such as skidders and hydraulic wood splitters, have been developed to mechanize production. Sawmill waste and construction industry by-products also include various forms of lumber tailings.

<i>Terra preta</i> Very dark, fertile Amazonian anthropogenic soil

Terra preta is a type of very dark, fertile anthropogenic soil (anthrosol) found in the Amazon Basin. It is also known as "Amazonian dark earth" or "Indian black earth". In Portuguese its full name is terra preta do índio or terra preta de índio. Terra mulata is lighter or brownish in color.

<span class="mw-page-title-main">Carbon sequestration</span> Storing carbon in a carbon pool (natural as well as enhanced or artificial processes)

Carbon sequestration is the process of storing carbon in a carbon pool. Carbon sequestration is a naturally occurring process but it can also be enhanced or achieved with technology, for example within carbon capture and storage projects. There are two main types of carbon sequestration: geologic and biologic.

<span class="mw-page-title-main">Smouldering</span>

Smouldering or smoldering is the slow, flameless form of combustion, sustained by the heat evolved when oxygen directly attacks the surface of a condensed-phase fuel. Many solid materials can sustain a smouldering reaction, including coal, cellulose, wood, cotton, tobacco, cannabis, peat, plant litter, humus, synthetic foams, charring polymers including polyurethane foam and some types of dust. Common examples of smouldering phenomena are the initiation of residential fires on upholstered furniture by weak heat sources, and the persistent combustion of biomass behind the flaming front of wildfires.

Pyrolysis oil, sometimes also known as bio-crude or bio-oil, is a synthetic fuel under investigation as substitute for petroleum. It is obtained by heating dried biomass without oxygen in a reactor at a temperature of about 500 °C (900 °F) with subsequent cooling. Pyrolysis oil is a kind of tar and normally contains levels of oxygen too high to be considered a pure hydrocarbon. This high oxygen content results in non-volatility, corrosiveness, immiscibility with fossil fuels, thermal instability, and a tendency to polymerize when exposed to air. As such, it is distinctly different from petroleum products. Removing oxygen from bio-oil or nitrogen from algal bio-oil is known as upgrading.

<span class="mw-page-title-main">Biochar</span> Lightweight black residue, made of carbon and ashes, after pyrolysis of biomass

Biochar is the lightweight black residue, made of carbon and ashes, remaining after the pyrolysis of biomass, and is a form of charcoal. Biochar is defined by the International Biochar Initiative as "the solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment". Biochar is a stable solid that is rich in pyrogenic carbon and can endure in soil for thousands of years.

<span class="mw-page-title-main">Virgin Earth Challenge</span>

The Virgin Earth Challenge was a competition offering a $25 million prize for whoever could demonstrate a commercially viable design which results in the permanent removal of greenhouse gases out of the Earth's atmosphere to contribute materially in global warming avoidance. The prize was conceived by Richard Branson, and was announced in London on 9 February 2007 by Branson and former US Vice President Al Gore.

<span class="mw-page-title-main">Soil carbon</span> Solid carbon stored in global soils

Soil carbon is the solid carbon stored in global soils. This includes both soil organic matter and inorganic carbon as carbonate minerals. It is vital to the soil capacity in our ecosystem. Soil carbon is a carbon sink in regard to the global carbon cycle, playing a role in biogeochemistry, climate change mitigation, and constructing global climate models. Natural variation such as organisms and time has affected the management of carbon in the soils. The major influence has been that of human activities which has caused a massive loss of soil organic carbon. An example of human activity includes fire which destroys the top layer of the soil and the soil therefore get exposed to excessive oxidation.

<span class="mw-page-title-main">Carbon dioxide removal</span> Removal of atmospheric carbon dioxide through human activity

Carbon dioxide removal (CDR), also known as carbon removal, greenhouse gas removal (GGR) or negative emissions, is a process in which carbon dioxide gas is removed from the atmosphere by deliberate human activities and durably stored in geological, terrestrial, or ocean reservoirs, or in products. In the context of net zero greenhouse gas emissions targets, CDR is increasingly integrated into climate policy, as an element of climate change mitigation strategies. Achieving net zero emissions will require both deep cuts in emissions and the use of CDR. CDR can counterbalance emissions that are technically difficult to eliminate, such as some agricultural and industrial emissions.

<span class="mw-page-title-main">Charcoal</span> Lightweight black carbon residue

Charcoal is a lightweight black carbon residue produced by strongly heating wood in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, called charcoal burning, often by forming a charcoal kiln, the heat is supplied by burning part of the starting material itself, with a limited supply of oxygen. The material can also be heated in a closed retort. Modern "charcoal" briquettes used for outdoor cooking may contain many other additives, e.g. coal.

<span class="mw-page-title-main">Hydrothermal carbonization</span>

Hydrothermal carbonization (HTC) is a chemical process for the conversion of organic compounds to structured carbons. It can be used to make a wide variety of nanostructured carbons, simple production of brown coal substitute, synthesis gas, liquid petroleum precursors and humus from biomass with release of energy. Technically the process imitates, within a few hours, the brown coal formation process which takes place in nature over enormously longer geological time periods of 50,000 to 50 million years. It was investigated by Friedrich Bergius and first described in 1913.

Soil management is the application of operations, practices, and treatments to protect soil and enhance its performance. It includes soil conservation, soil amendment, and optimal soil health. In agriculture, some amount of soil management is needed both in nonorganic and organic types to prevent agricultural land from becoming poorly productive over decades. Organic farming in particular emphasizes optimal soil management, because it uses soil health as the exclusive or nearly exclusive source of its fertilization and pest control.

<span class="mw-page-title-main">Top-lit updraft gasifier</span>

A top-lit updraft gasifier is a micro-kiln used to produce charcoal, especially biochar, and heat for cooking. A TLUD pyrolyzes organic material, including wood or manure, and uses a reburner to eliminate volatile byproducts of pyrolization. The process leaves mostly carbon as a residue, which can be incorporated into soil to create terra preta.

<span class="mw-page-title-main">Regenerative agriculture</span> Conservation and rehabilitation approach to food and farming systems

Regenerative agriculture is a conservation and rehabilitation approach to food and farming systems. It focuses on topsoil regeneration, increasing biodiversity, improving the water cycle, enhancing ecosystem services, supporting biosequestration, increasing resilience to climate change, and strengthening the health and vitality of farm soil.

<span class="mw-page-title-main">Soil regeneration</span>

Soil regeneration, as a particular form of ecological regeneration within the field of restoration ecology, is creating new soil and rejuvenating soil health by: minimizing the loss of topsoil, retaining more carbon than is depleted, boosting biodiversity, and maintaining proper water and nutrient cycling. This has many benefits, such as: soil sequestration of carbon in response to a growing threat of climate change, a reduced risk of soil erosion, and increased overall soil resilience.

<span class="mw-page-title-main">Carbon farming</span> Agricultural methods that capture carbon

Carbon farming is a name for a variety of agricultural methods aimed at sequestering atmospheric carbon into the soil and in crop roots, wood and leaves. The aim of carbon farming is to increase the rate at which carbon is sequestered into soil and plant material with the goal of creating a net loss of carbon from the atmosphere. Increasing a soil's organic matter content can aid plant growth, increase total carbon content, improve soil water retention capacity and reduce fertilizer use. Carbon farming is one component of climate-smart agriculture.

Biochar carbon removal (BCR) is a negative emissions technology. It involves the production of biochar through pyrolysis of residual biomass and the subsequent application of the biochar in soils or durable materials. The carbon dioxide sequestered by the plants used for the biochar production is therewith stored for several hundreds of years, which creates carbon sinks.

References

  1. Biederman, L. A. (2012-12-31). "Biochar and its effects on plant productivity and nutrient cycling: a meta-analysis". GCB Bioenergy. 5 (2): 202–214. doi:10.1111/gcbb.12037. S2CID   86216355.
  2. Niu, Li-qin; Jia, Pu; Li, Shao-peng; Kuang, Jia-liang; He, Xiao-xin; Zhou, Wen-hua; Liao, Bin; Shu, Wen-sheng; Li, Jin-tian (October 2015). "Slash-and-char: An ancient agricultural technique holds new promise for management of soils contaminated by Cd, Pb and Zn". Environmental Pollution. 205: 333–339. doi:10.1016/j.envpol.2015.06.017.
  3. Top Down Burn of Maize Stalks - Less Smoke - Make Biochar , retrieved 2022-12-17
  4. STOP BURNING BRUSH!, Make Easy Biochar, Every Pile is an Opportunity! , retrieved 2022-12-17
  5. 1 2 Lehmann – Biochar sequestration in terrestrial ecosystems, supra note 11 at 407 (“If this woody aboveground biomass were converted into biochar by means of simple kiln techniques and applied to soil, more than 50% of this C would be sequestered in a highly stable form.”)