What Is Biochar?
Biochar is charcoal produced by heating organic material at a high temperature in limited oxygen. It is a stable product, very rich in carbon, which is used to lock carbon into the soil.
Anyone can make charcoal. Just burn some wood. At high temperatures you get a more pure product with additional beneficial qualities. Of these positive properties, the one we are focussing on is its ability to rejuvenate the planet and its soil.
Biochar is a solid material obtained from the carbonisation of biomass. Biochar may be added to soils with the intention to improve soil functions and to reduce emissions from biomass that would otherwise naturally degrade to greenhouse gases. Biochar also has appreciable carbon sequestration value. These properties are measurable and verifiable in a characterisation scheme, or in a carbon emission offset protocol.
This 2,000 year-old practice converts agricultural waste into a soil enhancer that can hold carbon, boost food security, and increase soil biodiversity, and discourage deforestation. The process creates a fine-grained, highly porous charcoal that helps soils retain nutrients and water.
Biochar is found in soils around the world as a result of vegetation fires and historic soil management practices. Intensive study of biochar-rich dark earths in the Amazon (terra preta), has led to a wider appreciation of biochar’s unique properties as a soil enhancer.
Biochar can be an important tool to increase food security and cropland diversity in areas with severely depleted soils, scarce organic resources, and inadequate water and chemical fertilizer supplies.
Biochar also improves water quality and quantity by increasing soil retention of nutrients and agrochemicals for plant and crop utilization. More nutrients stay in the soil instead of leaching into groundwater and causing pollution.
Biochar has been described as :-
“the single most important initiative for humanity’s environmental future. It allows us to address food security, the fuel crisis, and the climate problem, all in an immensely practical manner.”
—Prof Tim Flannery, Australian of the Year 2007
What Are The Benefits of Biochar?
Digging Biochar into the earth has been shown to bring about many beneficial and long-term positive effects on soil.
- increase the water holding capacity of the soil
- increase crop production
- increase soil carbon levels
- increase soil pH
- decrease aluminium toxicity
- positively change the microbiology of the soil
- decrease soil emissions of the greenhouse gases CO2, N2O and CH4
- improve soil conditions for earthworm populations
- improve fertiliser use efficiency
The effects of Biochar will vary with soil type and the qualities of the Biochar used. Studies so far have shown that the greatest positive effects of Biochar applications have been in highly degraded, acidic or nutrient-depleted soils.
How is Biochar made?
Biochar can be produced from any organic material such as household green waste, paper waste or agricultural waste. It is made in a specially constructed incinerator that heats the organic material under pressure at temperatures above 430°C. The process, called pyrolysis, efficiently decomposes the bio matter, producing the Biochar solid, a small amount of bio-oil, and gases whose heat can be use to create electricity. The production of Biochar is a carbon negative process overall.
How does Bio-char help with climatechange?
Burning trees and agricultural waste contributes a large amount of carbon dioxide (CO2) to the atmosphere. The production and use of biochar breaks into the CO2 cycle, releasing oxygen and drawing carbon from the atmosphere to hold it in the soil.
What techniques are currently used to characterise Biochar?
Currently research scientist are using a large range of analytical techniques to understand the structure, composition and interactions of biochar materials. The chemical structural aspects of biochar can be characterised spectroscopically (e.g. 13C-NMR, ESR, Raman), chemical/thermal analysis (TGA-MS, Py-GCMS) or microscopically (SEM, TEM). Chemical characteristics of biochar can be assessed using standard chemical and agricultural soil testing, although somemethods require modification. Ecotoxicological testing such as earthworm avoidance assays and plant germination inhibition assays can be used to test the ecological safety of the biochars.
How stable is it?
Studies of charcoal from natural fire and ancient anthropogenic activity indicate millennial-scale stability. However, the stability of modern biochar products is uncertain: it is difficult to establish the half life of newly produced biochar through short term experiments, and aging processes are expected to affect turnover in the longer term. The limited data available suggest that turnover time of newly produced biochar ranges from decades to centuries, depending on feedstock and process conditions. At the moment there is no established method to artificially age biochar and assess likely long term stability.
Is it safe to use?
Prior to the large-scale endorsement of biochar usage, its safe use with regard to human and environmental health needs to be assured. Pyrolysis systems that meet first world regulatory standards on emissions, health and safety have been demonstrated. Some biochars have been tested for toxicity, and found to meet quideline levels of dioxins, PAHs and heavy metals, The OECD ecotoxicological test involving response of earthworms has demonstrated lack of toxicity of biochar made from paper sludge. Air emissions from biochar production, and composition of the biochar product, are highly dependent on the production systems and the biomass feedstock. Therefore it is critical that the safety of all proposed facilities is assessed Where biochar is used as a soil conditioner it must conform to relevant Australian and international standards and legislation (e.g . the NSW Protection of the Environment Operations (Waste) Regulation). The “earthworm avoidance test”, an ecotoxicological test method prescribed by the OECD, can be used as an initial environmental test. It is a cheap test that is suitable for developing countries.
Is it economically viable?
The economic viability of biochar is dependent on the price of the product and the benefits to the user. The price will be affected by the cost of feedstock (which may be negative in the case of biomass that would incur a waste disposal fee), and returns from renewable energy generated in the pyrolysis process. Financial benefits to the user may include increased production and reduced fertiliser requirements. Furthermore, the biochar producer or user may benefit from some form of carbon credit under an emissions trading scheme: the producer could receive credit for stabilising organic carbon, avoiding emissions from organic matter decomposition; alternatively, the landholder may receive credit for increasing the soil carbon stock in his field where biochar is applied. Thus the economic viability of biochar is influenced by policy; uncertainty over future policy may risk investment in biochar production facilities. The growing cost of waste disposal, and implementation of renewable energy targets, are likely to make the production and application of biochar for electricity and waste management economically viable. Potential returns from carbon trading will be enhanced if biochar is accepted under the Clean Development Mechanism (CDM) of the Kyoto Protocol.
What are the environmental and social benefits?
Models exist for viable agronomic use of biochar in subsistence agriculture. However, appropriate technology and policy needs to be implemented to deal with environmental issues such as methane and particulate emissions, that could contribute to climate change and human health risks. Socio-economic constraints and benefits are areas for ongoing research. Higher crop yields resulting from biochar applications would be expected to mitigate pressures on land and would also have relevance to land restoration and remediation. Other environmental benefits may include waste re-use and avoided landfill, offset of fossil fuels through renewable energy production, carbon sequestration, potentially reduced soil emissions of non-CO2 GHGs, improved crop performance and biomass production.
There’s nothing new about Biochar either..
Biochar is one of the oldest soil amendments in the history of agriculture. However, with the advent of modern agro-chemistry, the agronomic value of biochar got rapidly into oblivion. Only lately, when biochar got into focus as climate mitigation strategy, it’s function as soil amendment and nutrient carrier was rediscovered. All the more its fascinating to see that at the onset of modern agricultural chemistry in the 19th century, the use of charcoal was still and already known as key method to restore carbon to soil as well as for plant and soil nutrient cycling.
Biochar enthusiasts know of the Amazonians, who used biochar to create an agricultural civilization in an inhospitable rainforest environment. But we are not so aware of biochar history in Europe and America in 19th century. It began with Justus Liebig, the “father of organic chemistry” who wrote that charcoal “surpasses all other substances in the power which it possesses of condensing ammonia within its pores… it absorbs 90 times its volume of ammoniacal gas, which may be again separated by simply moistening it with water.” (Agricultural Chemistry, p 35.) This simple statement launched a wave of practical experimentation using charcoal for agriculture and waste management that lasted for nearly a century. The evidence is found in hundreds of reports published in science and agriculture journals. Some of these early proponents of biochar developed visionary proposals for reforming agriculture and civilization. They articulated their proposals with the same urgency and moral sense that we use today when discussing issues like climate change, food security and energy security. In the 19th century, the issues that biochar could help solve were related to health, disease, poverty, and above all, the recycling of human sewage to replenish the soil.
BIOCHAR LINKS – http://www.anzbiochar.org/links.html
This is a great book to purchase on Biochar, you can get it from the Diggers Club for $39 delivered to your door.