Farmers Can Add Activated BioChar to Open Fields for Erosion Control

What type of Carbon is best to Capture?

“Carbon isn’t a difficult element to spot in your daily life. For instance, if you’ve used a pencil, you’ve seen carbon in its graphite form. Similarly, the charcoal briquettes on your barbeque are made out of carbon, and even the diamonds in a ring or necklace are a form of carbon (in this case, one that has been exposed to high temperature and pressure). What you may not realize, though, is that about 18% of your body (by weight) is also made of carbon. In fact, carbon atoms make up the backbone of many important molecules in your body, including proteins, DNA, RNA, sugars, and fats.

These complex biological molecules are often called macromolecules; they’re also classified as organic molecules, which simply means that they contain carbon atoms. (Notably, there are a few exceptions to this rule. For example, carbon dioxide CO2 and carbon monoxide CO contain carbon, but generally aren’t considered to be organic.)” – Carbon and hydrocarbons | Khan Academy

The carbon capture that benefits the earth, environment, and humans the most is to capture both CO and CO2, but they both have several options in attaining that goal. The methodology contained herein focuses on the capture of Carbon Dioxide CO2 and storing it in soils.

Putative structure of charcoal from Verheijen et al 2010
Putative structure of charcoal from Verheijen et al 2010

Carbon Sequestration Explained

“Carbon sequestration can mean capturing the carbon dioxide (CO2) produced from new and old coal-powered power plants and large industrial sources before it is released in the atmosphere. Once captured, the CO2 is put into long term storage either by storing it in carbon sinks (such as oceans, forests or soils) or underground injection and geologic sequestration into deep underground rock formations.
“Developing technologies to reduce the rate of increase of atmospheric concentration of carbon dioxide (CO2) from annual emissions of 8.6 Pg C yr–1from energy, process industry, land-use conversion and soil cultivation is an important issue of the twenty-first century. Of the three options of reducing the global energy use, developing low or no-carbon fuel and sequestering emissions, this manuscript describes processes for carbon (CO2) sequestration and discusses abiotic and biotic technologies. Carbon sequestration implies transfer of atmospheric CO2 into other long-lived global pools including oceanic, pedologic, biotic and geological strata to reduce the net rate of increase in atmospheric CO2. Engineering techniques of CO2 injection in deep ocean, geological strata, old coal mines and oil wells, and saline aquifers along with mineral carbonation of CO2 constitute abiotic techniques. These techniques have a large potential of thousands of Pg, are expensive, have leakagerisks and may be available for routine use by 2025 and beyond. In comparison, biotic techniques are natural and cost-effective processes, have numerous ancillary benefits, are immediately applicable but have finite sink capacity. Biotic and abiotic C sequestration options have specific nitches, are complementary, and have potential to mitigate the climate change risks.” Carbon sequestration by Rattan Lal

A forest is considered to be a carbon sink if the trees in it absorb more carbon from the atmosphere than it releases. Carbon dioxide is a vital gas. It is necessary for photosynthesis. Carbon is absorbed from the atmosphere through photosynthesis.

During photosynthesis, trees and plants “sequester,” or absorb, carbon from the atmosphere in the form of CO2, and turn water and carbon dioxide into oxygen and sugar called glucose. Trees take in carbon dioxide from the air and store it as carbon in forest biomass, that is, trunks, branches, roots and leaves, in dead organic matter like litter and dead wood and in soils. This process of carbon absorption and deposition is known as carbon sequestration.” – Rinkesh Kukreja Conserve Energy Future

Types of Carbon Sequestration

1. Biological Carbon Sequestration

This, roughly, is the storage of carbon dioxide in vegetation like grasslands and forests, as well as in soils and oceans.

In soils: carbon can be sequestered in soil by plants through photosynthesis. As such, agroecosystems degrade and deplete the soil organic carbon levels. Luckily, soil can also store carbon as carbonates, created over thousands of years when carbon dioxide dissolves in water and percolates the soil. The carbonates are inorganic and can store carbon for tens of thousands of years while soil organic matter stores carbon for a few decades.

Carbon is the main component of the organic matter that makes fertile agricultural soil. It also helps the soil retain water. Plants are the primary way that CO2 is transferred to soil. Not all of the CO2 that plants suck up for photosynthesis is needed for food. The excess goes down through their roots and feeds organisms that live in the soil. Carbon from the roots and leaves of dying plants is also captured in soil.

2. Geological Carbon Sequestration

This is where carbon dioxide is stored in underground geologic formations, such as in rocks. Industrial sources of carbon dioxide such as steel or cement production companies or energy-related sources like power plants or natural gas processing facilities will release their carbon dioxide, which is then injected into porous rocks for long-term storage. Such carbon capture and storage allows the use of fossil fuels until a substitute energy source is introduced on a large scale

3. Technological Carbon Sequestration

This is a relatively new way of capturing and storing carbon dioxide and continues to be explored by scientists. The method uses innovative technologies, which means scientists are also looking into more ways of using carbon dioxide as a resource rather than removing it from the atmosphere and directing it elsewhere.

  1. Graphene production: technology is being used to produce graphene from carbon dioxide as its raw material. Graphene is a technological material, used to create screens for smartphones and other technological devices. Its production is limited to specific industries but if carbon can be used to make more of the product, it might be a viable resource and an effective solution in reducing carbon’s emissions from the atmosphere.
  2. Engineered molecules: scientists are engineering molecules that can take new shapes by creating new compounds capable of singling out and capturing carbon dioxide from the air. These engineered molecules act as filters and only attract the element they are engineered to seek.
  3. Direct air capture (DAC): this is a means of capturing carbon dioxide from the air using advanced technology plants. The plants would seek to capture carbon dioxide from the air as the artificial ones do. It is an effective technological method of sequestrating carbon but it has its challenges. The project is energy-intensive and is also expensive to implement on a mass scale. It is estimated that between $500 and $800 is required for every ton of carbon removed.

4. Industrial Carbon Sequestration

This is not a widely renowned method, but it can be used in some industries. They capture the carbon in three ways from a power plant, pre-combustion, post-combustion and oxyfuel

  1. Pre-combustion: the carbon is captured in power plants before the fuel is burned. The aim is to remove the carbon from coal before it is burned. The coal is reacted with oxygen to produce synthesis gas, a mixture of carbon monoxide and hydrogen gases. The hydrogen is removed and either burned directly as fuel or compressed and stored in fuel-cell cars. Water is then added to the carbon monoxide to make carbon dioxide which is then stored and the extra hydrogen is stored with the hydrogen previously removed
  2. Post-combustion: here, carbon is removed from a power station’s output after the fuel has been burned. This means waste gases are captured and scrubbed clean of their carbon dioxide before they travel up smokestacks. This is achieved by passing the gases through ammonia, which is then blasted clean with steam, releasing carbon dioxide for storage.
  3. Oxyfuel or oxy-combustion: the point is to burn fuel in more oxygen and store all the gases produced as a result. Instead of laboriously separating the carbon dioxide from other waste gases, the process traps the entire output from the smokestacks and stores it all. Pure oxygen is blown into the furnaces to purify the exhaust, so the fuel burns completely, producing relatively pure steam and carbon dioxide gas. Once the steam is removed by cooling and condensation, making it into water, the carbon dioxide can be safely stored.

What can the average farmer do to increase the carbon capture ability of their land, and does that effort have any other benefits other than sequestration?

  1. Adding bio-char to any soil type can improve the soil’s mycology, water retention, erosion control, and organic life concentrations, especially when the charcoal is soaked in heavy fungal teas and microbial mixtures prior to application to the soil.
  2. Adding 1 ton of BioChar to the average field is suggested.
    Only ⅓ of that is required if the char is activated.
  3. Activating BioChar requires some soaking of the fresh char in microbial tea, which also has mycology in it. We take Gro-Kashi and make tea with EM1 product from TerraGanix that then has RootWise Biodynamic added which will need to mix for at least 30 minutes prior to soaking the char.
  4. For small batches of inoculation and soaking, we have put the soaking char in a vacuum chamber at 50 PSI for 20 minutes, thus allowing the char to be fully permeated with the microbial and mycological tea.
  5. Activated BioChar has shown an increase of up to 880% in crop yield in volume, and an increase of up to 75% higher nutrition content.

How does one make Abiotic Charcoal?

Pyrolysis VS. Gasification

“Abstract: Biochar produced from biomass pyrolysis is becoming a powerful tool for carbon sequestration and greenhouse gas (GHG) emission reduction.Biochar Crecalcitrance or biochar stability is the decisive property determining it’s carbon sequestration potential. The effect of pyrolysis process parameters on biochar stability is becoming a frontier of biochar study. This review discussed comprehensively how and why Biomass compositions and physicochemical properties and biomass processing conditions such as pyrolysis temperature and reaction residence time affect the stability of biochar. The review found that relative high temperature (400700 C), long reaction residence time, slow heating rate, high pressure, the presence of some minerals and biomass feedstock of highlignin content with large particle size are preferable to biochar stability. However, challenges exist to mediate the tradeoffs between biochar stability and other potential wins.Strategies were proposed to promote the utilization of biochar as a climate change mitigation tool.” – An overview of the effect of pyrolysis process parameters on biochar stability by Lijian Leng, Huajun Huang

“Thermo-chemical conversion technologies capable of creating biochar include pyrolysis and  gasification. Pyrolysis thermally decomposes biomass without the presence of oxygen to create  biochar at temperatures starting at 300⁰C. Gasification uses limited oxygen and higher  temperatures (500⁰C – 1,500⁰C) (Lehmann et al., 2015). A co-product of biochar production is  energy in the form of process heat, liquid fuel, or combustible gases that can be used to supply  heat or electricity.

A single laborer can produce 64 tons of biochar per growing season which is incorporated into  compost made up of 20% coffee husks, 50% pulp, 20% biochar and 10% top soil. The  composting process is still being optimized but currently takes about 8 weeks to finish.  50L/plant of biochar-compost blend is used for new field plantings per tree, of which 2.3 kg is biochar. The blend is deposited in a hole (80 – 100 cm in diameter and ca. 30-40 cm deep) prior  to placing the tree. On average the farm spends USD 1,050 per ha for the biochar compost.” – The Potential for Biochar to Improve Sustainability in Coffee Cultivation and Processing: A White Paper

Syngas Biochar Gasifier to produce abiotic Charcoal

Handbook of Biomass Downdraft Gasifier Engine Systems – March 1988

This handbook has been prepared by the Solar Energy Research Institute under the U.S. Department of Energy Solar Technical Information Program. It is intended as a guide to the design, testing, operation, and manufacture of small-scale [less than 200 kW(270 hpJ] gasifiers. A great deal of the information will be useful for all levels of biomass gasification.

Functional Specification for the Biochar

Start by defining the desired qualities and properties of the biochar. These could include:

  • Water holding capacity, surface area, pore volume
  • Mineralisable and persistent carbon content
  • Liming ability, pH, available N, P, K
  • Total macro- and micro-nutrient content
  • Cation and Anion exchange capacity
  • Ability to adsorb heavy metals and other toxic compounds
  • Average particle size, bulk and particle density
  • Polyaromatic hydrocarbons and dioxin content
    See guide “Properties of Fresh and Aged Biochar” for more detail

 

There are several areas that deserve attention for a solution of what to do with excess carbon, in all of it’s molecular forms

  • how to “make” carbon,
  • Does carbon need to be cleaned for use,
  • how to manage the bi-products of making carbon,
  • What is the measurement of carbon capture,
  • How long is the carbon captured for
  • What is the increase in fruit yield that X amount of carbon will produce
  • Carbon Credits can be achieved with what kind of implementation?
  • How does a farmer get started with carbon credits?

According to recent research from Thomas Crowther at ETH Zurich, roughly 3 trillion trees grow on the earth at present and in total, they sequester on the order of 400 Gigatons of carbon dioxide. Crowther and his team figure that enough land exists to be able to plant an additional 1.2 trillion more trees without affecting agricultural production. Were this many trees to be planted, we would succeed in sequestering the better part of the last decade’s worth of carbon emissions.” – Planting 1.2 Trillion Trees Could Cancel Out a Decade of CO2 Emissions, Scientists Find

3,000,000,000,000 trees = 400 Gigatons of Carbon Monoxide (CO) sequestration

“Why trees don’t sequester. Very often, tree planting is recommended to sequester carbon from the atmosphere. This is a misinterpretation of the role of plants in the carbon cycle. Biomass fails to permanently sequester carbon from the atmosphere for several reasons.

  1. Plants constitute an open system that is in balance with the atmosphere. What is taken up will be released with some time delay. (Figure 4)
  2. Newly planted biomass will sequester carbon maximally only at the middle of its development to maturation. (Figure 5, solid line). This means that, when you plant a forest for carbon sequestration, the rate of carbon sequestering will increase the first 40-50 years of their growth. After that, the rate will diminish until full growth, when respiration will equal their uptake of carbon.
  3. At full growth, say 100 – 150 years after the establishment of the forest, the plants have stored carbon maximally (grey field in Figure 5). Any disturbance after this time will release carbon into the air again. So, you cannot harvest the forest, nor should you allow pest, disease or fire.

This is a clearly unsustainable situation. Thus, assuming that increased tree planting will counteract carbon dioxide contamination from fossil fuel burning is, to say the least, a short-sighted solution. Naturally, this is even truer when talking of annual plants, such as most agricultural crops. However, a strategy to increase the dynamic plant cover will increase the amount of the carbon dioxide sequestered from the atmosphere. Some such strategies will be discussed below.

Due to its porosity and thus its large internal area, up to 1500 m2/g 17, charcoal has an excellent capacity to adsorb nutrients and organic material, and hence also works as a very good habitat and growth area for soil micro-organisms. Therefore, in any poor soil, such as excessively sandy, clayey or leaky soils, the addition of charcoal is a good way to improve it. The charcoal works as a ‘sponge’ for the nutrients, which due to the increased microbial biomass are accessible for the plants growing nearby. (Plants ‘buy’ nutrients from micro-organisms with sugars released from their roots). Charcoal also exerts significant effects on the decomposition of added litter. The increased amount of microbial biomass has also a positive effect of the growth of earthworm populations (which feed on micro-organisms), something that will further augment the productivity of the soil18.

http://www.holon.se/folke/carbon/Terra%20pretav1_0.pdf

Glossary:

  1. A Retort is an airtight vessel in which substances are externally heated, usually producing gases to be collected in a collection vessel, or for further processes.
  2. Batch Pyrolysers are simple low-cost devices that are filled with biomass, run to completion and then emptied.
  3. Basic batch stoves, retorts and kilns are often used for small-scale manufacture of biochar, and also for larger scale production of fuel- or process-charcoal (eg for reducing metals).
  4. Continuous Pyrolysers are devices where biomass is fed into one end while biochar is continuously discharged from the other.
    Continuous devices are more complex and expensive, but can provide:

    • more production from a given amount of equipment and labor
    • more control over the process conditions of the biochar
    • lower emissions
  5. Reactor (or more specifically a chemical reactor) is a vessel designed to contain and control (chemical) reactions.
  6. A Pyrolyser is a reactor designed for thermal decomposition of biomass in a limited oxygen environment (= pyrolysis).
  7. A Gasifier is a reactor in which air is intentionally injected into the feedstock. Part of the feedstock is burned to produce a relatively clean pyrogas. A gasifier usually operates at a higher temperature than a pyrolyser.
  8. A Stove is an enclosed space in which fuel is burned to provide heating, either to heat the stove itself and the space in which it is situated, or to heat items placed on the stove.
  9. A Kiln is a kind of oven, a thermally insulated chamber,that produces temperatures sufficient to complete some process, such as drying, or chemical change. A kiln may be internally or externally heated.
  10. Pyrogas (or Pyrolysis gas): The gas and aerosols from pyrolysis or gasification comprising primarily combustible gases CO, H2and CH4along with CO2, steam and N2; also known as wood gas and syngas.
  11. Primary Air (PA):  In pyrolysis PA refers to air supplied to the fuel bed, needed to partially combust the material resulting in emission of combustible vapoursand gases.If pyrolysis is sustained by external heat, PA provides a fraction of the air required for first stage combustion of emitted gases.
  12. Secondary Air (SA): (and in some instances tertiary air) refers to additional air injected to the combustion zone to complete combustion of the fuel gases.
  13. Materials Handling: This refers to the equipment that moves the biomass to the pyrolyserand moves the biochar from the pyrolyser.
  14. Materials Preparation Equipment: This includes machinery that reduces the size (e.g. grinders), compacts the biomass into pellets or briquettes, dries the biomass, or mixes ingredients (such as biomass and minerals) together.

Do Endophytes Promote Growth of Host Plants Under Stress?

A Meta-Analysis on Plant Stress Mitigation by Endophytes

Hyungmin Rho 1 & Marian Hsieh 1 & Shyam L. Kandel1 & Johanna Cantillo 2 &
Sharon L. Doty1 & Soo-Hyung Kim 1

Abstract

Endophytes are microbial symbionts living inside plants and have been extensively researched in recent decades for their functions associated with plant responses to environmental stress. We conducted a meta-analysis of endophyte effects on host plants’ growth and fitness in response to three abiotic stress factors: drought, nitrogen deficiency, and excessive salinity. Ninety-four endophyte strains and 42 host plant species from the literature were evaluated in the analysis. Endophytes increased biomass accumulation of host plants under all three stress conditions. The stress mitigation effects by endophytes were similar among different plant taxa or functional groups with few exceptions; eudicots and C4 species gained more biomass than monocots and C3 species with endophytes, respectively, under drought conditions. Our analysis supports the effectiveness of endophytes in mitigating drought, nitrogen deficiency, and salinity stress in a wide range of host species with little evidence of plant-endophyte specificity.

Keywords

Bacteria, fungi, yeast, Drought stress, nitrogen stress, salinity stress, Effect size Endophytes, Meta-analysis, Plant biomass

Do Endophytes Promote Growth of Host Plants Under Stress? A Meta-Analysis on Plant Stress Mitigation by Endophytes

Diazotrophic Endophytes of Poplar and Willow for Growth Promotion of Rice Plants in Nitrogen-Limited Conditions

S. L. Kandel, N. Herschberger, S.H. Kim, and S. L. Doty*
School of Environmental and Forest Sciences, College of the Environment, Univ. of Washington, Seattle, WA 98195-2100. Received 20 Aug. 2014. Accepted 16 Mar. 2015. *Corresponding author (sldoty@uw.edu).

Abbreviations:

  • BNF, biological N fiation;
  • GFP, green florescent protein;
  • IAA, indole-3-acetic acid;
  • MG/L, Mannitol Glutamate/Luria;
    MS, Murashige–Skoog;
  • NL-CCM, N-limited combined C medium.
    ABSTRACT
    rice (Oryza sativa L.) is one of the most important staple food crops. Its cultivation requires a relatively high input of N fertilizers; however, rice plants do not absorb a signifiant proportion of added fertilizers, resulting in soil and water pollution. The use of diazotrophic (N-fiing) endophytes can provide benefis for rice cultivation by reducing the demand of N fertilizers. Diazotrophic endophytes from the early successional plant species poplar (Populus trichocarpa Torr. & A. Gray) and willow (Salix sitchensis C. A. Sanson ex Bong.) were added to rice seedlings.
    Inoculated rice plants were grown in N-limited conditions in the greenhouse, and plant physical characteristics were assessed. Endophyte-inoculated rice plants had greater biomass, higher tiller numbers, and taller plant stature than mockinoculated controls. Endophyte populations were quantifid and visualized in planta within rice plants using florescent microscopy. The endophytes colonized rice plants effectively in both roots and foliage. These results demonstrated that diazotrophic endophytes of the eudicots poplar and willow can colonize rice plants and enhance plant growth in N-limited conditions.
Diazotrophic Endophytes of Poplar and Willow for Growth Promotion of Rice Plants in Nitrogen-Limited Conditions

Terra Preta | Amazonian Black Earth

A former worker at a plant farm in East Texas who was from the mountains of Mexico showed me a process that he believed made for the best area for a garden. His suggestion:

Dig a hole about 4 foot down then fill with wood, burn it, enjoy the time, then when you go to put it out, put wood on the coals, cover with the dirt again, go to bed. Go back and dig out the dirt, then the charcoal. If it is all carbon then just add good, clean, ph balanced water to it and see if an oily sheen is on the top of the water surface, and how quickly it drains out. IF No sheen of rainbow and the water takes a good while to drain, then it is good to return the charcoal to the soaked area, add “ready made compost rich” (living) soil on top, (or breathable fabric bag full of living soil.) Then add your young plant or group of plants to the hole.

Brazilian Charcoal Making Buildings-1930
Brazilian Charcoal Making Buildings-1930

This method has proven to be a great success for non-row farming in raised bed type gardening.

There are several ways to add carbon to the soil, as well as many other things that could be added in this process, and it is interesting to note that Native Americans have been doing something similar for a very long time.

Terra preta (Portuguese pronunciation: [ˈtɛʁɐ ˈpɾetɐ], locally [ˈtɛha ˈpɾeta], literally "black soil" in Portuguese) is a type of very dark, fertile artificial (anthropogenic) soil 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 ("black soil of the Indian", "Indians' black earth"). Terra mulata ("mulatto earth") is lighter or brownish in color.[1]

Homemade terra preta, with charcoal pieces indicated using white arrows

Terra preta owes its characteristic black color to its weathered charcoal content,[2] and was made by adding a mixture of charcoal, bone, broken pottery, compost and manure to the low fertility Amazonian soil. A product of indigenous soil management and slash-and-char agriculture,[3] the charcoal is stable and remains in the soil for thousands of years, binding and retaining minerals and nutrients.[4][5]

Terra preta is characterized by the presence of low-temperature charcoal residues in high concentrations;[2] of high quantities of tiny pottery shards; of organic matter such as plant residues, animal feces, fish and animal bones, and other material; and of nutrients such as nitrogen, phosphorus, calcium, zinc and manganese.[6] Fertile soils such as terra preta show high levels of microorganic activities and other specific characteristics within particular ecosystems.

Terra preta zones are generally surrounded by terra comum ([ˈtɛhɐ koˈmũ] or [ˈtɛhɐ kuˈmũ]), or "common soil"; these are infertile soils, mainly acrisols,[6] but also ferralsols and arenosols.[7] Deforested arable soils in the Amazon are productive for a short period of time before their nutrients are consumed or leached away by rain or flooding. This forces farmers to migrate to an unburned area and clear it (by fire).[8][9] Terra preta is less prone to nutrient leaching because of its high concentration of charcoal, microbial life and organic matter. The combination accumulates nutrients, minerals and microorganisms and withstands leaching.

Terra preta soils were created by farming communities between 450 BCE and 950 CE.[10][11][12] Soil depths can reach 2 meters (6.6 ft). It is reported to regenerate itself at the rate of 1 centimeter (0.4 in) per year.[13]

History

Early theories

The origins of the Amazonian dark earths were not immediately clear to later settlers. One idea was that they resulted from ashfall from volcanoes in the Andes, since they occur more frequently on the brows of higher terraces. Another theory considered its formation to be a result of sedimentation in tertiary lakes or in recent ponds.[citation needed]

Anthropogenic roots

Soils with elevated charcoal content and a common presence of pottery remains can accrete accidentally near living quarters as residues from food preparation, cooking fires, animal and fish bones, broken pottery, etc., accumulated. Many terra preta soil structures are now thought to have formed under kitchen middens, as well as being manufactured intentionally on larger scales.[14] Farmed areas around living areas are referred to as terra mulata. Terra mulata soils are more fertile than surrounding soils but less fertile than terra preta, and were most likely intentionally improved using charcoal.[citation needed]

This type of soil appeared between 450 BCE and 950 CE at sites throughout the Amazon Basin.[12] Recent research has reported that terra preta may be of natural origin, suggesting that pre-Colombian people intentionally utilized and improved existing areas of soil fertility scattered among areas of lower fertility..[15]

Amazonia

Amazonians formed complex, large-scale social formations, including chiefdoms (particularly in the inter-fluvial regions) and even large towns and cities.[16] For instance, the culture on the island of Marajó may have developed social stratification and supported a population of 100,000. Amazonians may have used terra preta to make the land suitable for large-scale agriculture.[17]

Spanish explorer Francisco de Orellana was the first European to traverse the Amazon River in the 16th century. He reported densely populated regions extending hundreds of kilometres along the river, suggesting population levels exceeding even those of today. Orellana may have exaggerated the level of development, although that is disputed. The evidence to support his claim comes from the discovery of geoglyphs dating between 0–1250 CE and from terra preta.[18][19] Beyond the geoglyphs, these populations left no lasting monuments, possibly because they built with wood, which would have rotted in the humid climate, as stone was unavailable.[citation needed]

Whatever its extent, this civilization vanished after the demographic collapse of the 16th and 17th century, due to European-introduced diseases such as smallpox.[19] The settled agrarians again became nomads, while still maintaining specific traditions of their settled forbears. Their semi-nomadic descendants have the distinction among tribal indigenous societies of a hereditary, yet landless, aristocracy, a historical anomaly for a society without a sedentary, agrarian culture.[citation needed]

Moreover, many indigenous peoples adapted to a more mobile lifestyle to escape colonialism. This might have made the benefits of terra preta, such as its self-renewing capacity, less attractive: farmers would not have been able to cultivate the renewed soil as they migrated. Slash-and-char agriculture may have been an adaptation to these conditions. For 350 years after the European arrival, the Portuguese portion of the basin remained untended.[citation needed]

Location

Terra preta soils are found mainly in the Brazilian Amazon, where Sombroek et al.[20] estimate that they cover at least 0.1 to 0.3%, or 6,300 to 18,900 square kilometres (2,400 to 7,300 sq mi) of low forested Amazonia;[1] but others estimate this surface at 10.0% or more (twice the area of Great Britain).[13][21] Recent model-based predictions suggest that the extent of terra preta soils may be of 3.2% of the forest.[22]

Terra preta exists in small plots averaging 20 hectares (49 acres), but areas of almost 360 hectares (890 acres) have also been reported. They are found among various climatic, geological, and topographical situations.[1] Their distributions either follow main water courses, from East Amazonia to the central basin,[23] or are located on interfluvial sites (mainly of circular or lenticular shape) and of a smaller size averaging some 1.4 hectares (3.5 acres), (see distribution map of terra preta sites in Amazon basin[24] The spreads of tropical forest between the savannas could be mainly anthropogenic—a notion with dramatic implications worldwide for agriculture and conservation.[25]

Terra preta sites are also known in the Llanos de Moxos of Bolivia, Ecuador, Peru and French Guiana,[26][27] and on the African continent in Benin, Liberia, and the South African savannas.[6]

Pedology

In the international soil classification system World Reference Base for Soil Resources (WRB) Terra preta is called Pretic Anthrosol. The most common original soil before transformed into a terra preta is the Ferralsol. Terra preta has a carbon content ranging from high to very high (more than 13–14% organic matter) in its A horizon, but without hydromorphic characteristics.[28] Terra preta presents important variants. For instance, gardens close to dwellings received more nutrients than fields farther away.[29] The variations in Amazonian dark earths prevent clearly determining whether all of them were intentionally created for soil improvement or whether the lightest variants are a by-product of habitation.[citation needed]

Terra preta's capacity to increase its own volume—thus to sequester more carbon—was first documented by pedologist William I. Woods of the University of Kansas.[13] This remains the central mystery of terra preta.[citation needed]

The processes responsible for the formation of terra preta soils are:[7]

  • Incorporation of wood charcoal
  • Incorporation of organic matter and of nutrients
  • Growth of microorganisms and animals in the soil

Wood charcoal

The transformation of biomass into charcoal produces a series of charcoal derivatives known as pyrogenic or black carbon, the composition of which varies from lightly charred organic matter, to soot particles rich in graphite formed by recomposition of free radicals.[30][31] All types of carbonized materials are called charcoal. By convention, charcoal is considered to be any natural organic matter transformed thermally or by a dehydration reaction with an oxygen/carbon (O/C) ratio less than 60;[30] smaller values have been suggested.[32] Because of possible interactions with minerals and organic matter from the soil, it is almost impossible to identify charcoal by determining only the proportion of O/C. The hydrogen/carbon percentage[33] or molecular markers such as benzenepolycarboxylic acid,[34] are used as a second level of identification.[7]

Indigenous people added low temperature charcoal to poor soils. Up to 9% black carbon has been measured in some terra preta (against 0.5% in surrounding soils).[35] Other measurements found carbon levels 70 times greater than in surrounding ferralsols,[7] with approximate average values of 50 Mg/ha/m.[36]

The chemical structure of charcoal in terra preta soils is characterized by poly-condensed aromatic groups that provide prolonged biological and chemical stability against microbial degradation; it also provides, after partial oxidation, the highest nutrient retention.[7][36] Low temperature charcoal (but not that from grasses or high cellulose materials) has an internal layer of biological petroleum condensates that the bacteria consume, and is similar to cellulose in its effects on microbial growth.[37] Charring at high temperature consumes that layer and brings little increase in soil fertility.[13] The formation of condensed aromatic structures depends on the method of manufacture of charcoal.[34][38][39] The slow oxidation of charcoal creates carboxylic groups; these increase the cations' exchange capacity of the soil.[40][41] The nucleus of black carbon particles produced by the biomass remains aromatic even after thousands of years and presents the spectral characteristics of fresh charcoal. Around that nucleus and on the surface of the black carbon particles are higher proportions of forms of carboxylic and phenolic carbons spatially and structurally distinct from the particle's nucleus. Analysis of the groups of molecules provides evidences both for the oxidation of the black carbon particle itself, as well as for the adsorption of non-black carbon.[42]

This charcoal is thus decisive for the sustainability of terra preta.[40][43] Amending ferralsol with wood charcoal greatly increases productivity.[23] Globally, agricultural lands have lost on average 50% of their carbon due to intensive cultivation and other damage of human origin.[13]

Fresh charcoal must be "charged" before it can function as a biotope.[44] Several experiments demonstrate that uncharged charcoal can bring a provisional depletion of available nutrients when first put into the soil, that is until its pores fill with nutrients. This is overcome by soaking the charcoal for two to four weeks in any liquid nutrient (urine, plant tea, etc.).[citation needed]

Organic matter and nutrients

Charcoal's porosity brings better retention of organic matter, of water and of dissolved nutrients,[40][45] as well as of pollutants such as pesticides and aromatic poly-cyclic hydrocarbons.[46]

Organic matter

Charcoal's high absorption potential of organic molecules (and of water) is due to its porous structure.[7] Terra preta's high concentration of charcoal supports a high concentration of organic matter (on average three times more than in the surrounding poor soils),[7][36][41][47] up to 150 g/kg.[23] Organic matter can be found at 1 to 2 metres (3 ft 3 in to 6 ft 7 in) deep.[28]

Bechtold proposes to use terra preta for soils that show, at 50 centimeters (20 in) depth, a minimum proportion of organic matter over 2.0-2.5%. The accumulation of organic matter in moist tropical soils is a paradox, because of optimum conditions for organic matter degradation.[36] It is remarkable that anthrosols regenerate in spite of these tropical conditions' prevalence and their fast mineralisation rates.[23] The stability of organic matter is mainly because the biomass is only partially consumed.[36]

Nutrients

Terra preta soils also show higher quantities of nutrients, and a better retention of these nutrients, than surrounding infertile soils.[36] The proportion of P reaches 200–400 mg/kg.[48] The quantity of N is also higher in anthrosol, but that nutrient is immobilized because of the high proportion of C over N in the soil.[23]

Anthrosol's availability of P, Ca, Mn and Zn is higher than ferrasol. The absorption of P, K, Ca, Zn, and Cu by the plants increases when the quantity of available charcoal increases. The production of biomass for two crops (rice and Vigna unguiculata) increased by 38–45% without fertilization (P < 0.05), compared to crops on fertilized ferralsol.[23]

Amending with charcoal pieces approximately 20 millimeters (0.79 in) in diameter, instead of ground charcoal, did not change the results except for manganese (Mn), for which absorption considerably increased.[23]

Nutrient leaching is minimal in this anthrosol, despite their abundance, resulting in high fertility. When inorganic nutrients are applied to the soil, however, the nutrients' drainage in anthrosol exceeds that in fertilized ferralsol.[23]

As potential sources of nutrients, only C (via photosynthesis) and N (from biological fixation) can be produced in situ. All the other elements (P, K, Ca, Mg, etc.) must be present in the soil. In Amazonia, the provisioning of nutrients from the decomposition of naturally available organic matter fails as the heavy rainfalls wash away the released nutrients and the natural soils (ferralsols, acrisols, lixisols, arenosols, uxisols, etc.) lack the mineral matter to provide those nutrients. The clay matter that exists in those soils is capable of holding only a small fraction of the nutrients made available from decomposition. In the case of terra preta, the only possible nutrient sources are primary and secondary. The following components have been found:[36]

Saturation in pH and in base is more important than in the surrounding soils.[48][49]

Microorganisms and animals

The peregrine earthworm Pontoscolex corethrurus (Oligochaeta: Glossoscolecidae) ingests charcoal and mixes it into a finely ground form with the mineral soil. P. corethrurus is widespread in Amazonia and notably in clearings after burning processes thanks to its tolerance of a low content of organic matter in the soil.[50] This as an essential element in the generation of terra preta, associated with agronomic knowledge involving layering the charcoal in thin regular layers favorable to its burying by P. corethrurus.[citation needed]

Some ants are repelled from fresh terra preta; their density is found to be low about 10 days after production compared to that in control soils.[51]

Modern research on creating terra preta

Synthetic terra preta

A newly coined term is 'synthetic terra preta’.[52][53] STP is a fertilizer consisting of materials thought to replicate the original materials, including crushed clay, blood and bone meal, manure and biochar[52] is of particulate nature and capable of moving down the soil profile and improving soil fertility and carbon in the current soil peds and aggregates over a viable time frame.[54] Such a mixture provides multiple soil improvements reaching at least the quality of terra mulata. Blood, bone meal and chicken manure are useful for short term organic manure addition.[55] Perhaps the most important and unique part of the improvement of soil fertility is carbon, thought to have been gradually incorporated 4 to 10 thousand years ago.[56] Biochar is capable of decreasing soil acidity and if soaked in nutrient rich liquid can slowly release nutrients and provide habitat for microbes in soil due to its high porosity surface area.[2]

The goal is an economically viable process that could be included in modern agriculture. Average poor tropical soils are easily enrichable to terra preta nova by the addition of charcoal and condensed smoke.[57] Terra preta may be an important avenue of future carbon sequestration while reversing the current worldwide decline in soil fertility and associated desertification. Whether this is possible on a larger scale has yet to be proven. Tree Lucerne (tagasaste or Cytisus proliferus) is one type of fertilizer tree used to make terra preta. Efforts to recreate these soils are underway by companies such as Embrapa and other organizations in Brazil.[58]

Synthetic terra preta is produced at the Sachamama Center for Biocultural Regeneration in High Amazon, Peru. This area has many terra preta soil zones, demonstrating that this anthrosol was created not only in the Amazon basin, but also at higher elevations.[59]

A synthetic terra preta process was developed by Alfons-Eduard Krieger to produce a high humus, nutrient-rich, water-adsorbing soil.[60]

Terra preta sanitation

Terra preta sanitation (TPS) systems have been studied as an alternative sanitation option by using the effects of lactic-aid conditions in urine-diverting dry toilets and a subsequent treatment by vermicomposting.[61]

See also

Notes

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  3. ^ Dufour, Darna L. (October 1990). "Use of Tropical Rainforests by Native Amazonians". BioScience. 40 (9): 652–659. doi:10.2307/1311432. ISSN 0006-3568. JSTOR 1311432. Much of what has been considered natural forest in Amazonia is probably the result of hundreds of years of human use and management.
    Rival, Laura (1993). "The Growth of Family Trees: Understanding Huaorani Perceptions of the Forest". Man. 28 (4): 635–652. doi:10.2307/2803990. JSTOR 2803990.
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  7. ^ a b c d e f g Glaser 2007.
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  10. ^ Neves 2001, p. 10.
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References

External links