Many scientists view that Biochar is considered the Black Gold of Agriculture
Biochar is a hard fabric obtained from the carbonization thermochemical conversion of biomass in an oxygen limited environments. In more technical terms, biochar is produced by thermal decomposition of organic material (biomass such as wood chips, corn husk, peanut shells, manure or leaves) under limited supply of oxygen (O2), and at relatively low temperatures (<700°C).
This 2,000 year-old practice converts agricultural waste into a soil enhancer that can hold carbon, boost food security, and increase soil biodiversity, discourage deforestation and mitigate climate change. 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.
Its high carbon content and porous nature retain water, nutrient in the soil and protects soil microbes. It can increase crop yield while acting as a Natural carbon sink keeping carbon in the ground.
Biochar helps conserve plant nutrients by storing them within its matrix and making the nutrients available when the crops need them. This happens because of a property in biochar, certain clays.soil Organicmatter known as cation exchange capacity(CEC).
CEC is a measure of a biochar’s capacity to retain positive ions, such as ammonium and potassium ions, in an exchangeable form that is available to plants. CEC not only helps conserve the fertilizers added to the crop during the growing season, but also improves the soil’s ability to confine and retain nutrients from other sources available at other times . Biochar typically increases cation exchange capacity, and hence retention of NH4+, K+, Ca+, Mg2+.Nitrogen from original biomass, however, may not be readily available.Phosphorous, on the other hand, is generally retained and available. Biochar enhanced sorption of organics (herbicides, pesticides, enzymes).
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 makes a significant contribution to mycorrhiza by promoting soil microbe populations. Specifically, biochar:
- Detoxifies soil water by adsorbing compounds that inhibit microbe growth.
- Provides a protective habitat for microbes
- Improves soil moisture management.
- increased mycorrhizal populations, rhizobial infection rates
- Used as carrier for microbial-based environmental remediation
- Lowers bulk density
Climate smart benefit of Biochar
Carbon in biochar can persist in soils over long time scales. Beyond the carbon sequestered in the biochar itself, biochar incorporated in soils also offers numerous other potential climate benefits.
- Soil Fertility: Biochar can improve soil fertility, stimulating plant growth, which then consumes more CO2 in a positive feedback effect.
- Reduced fertilizer inputs: Biochar can reduce the need for chemical fertilizers, resulting in reduced emissions of greenhouse gases from fertilizer manufacture.
- Reduced N2O and CH4 emissions: Biochar can reduce emissions of nitrous oxide (N2O) and methane (CH4)—two potent greenhouse gases—from agricultural soils.
- Enhanced soil microbial life: Biochar can increase soil microbial life, resulting in more carbon storage in soil.
- Reduced emissions from feedstocks: Converting agricultural and forestry waste into biochar can avoid CO2 and CH4 emissions otherwise generated by the natural decomposition or burning of the waste.
- Energy generation: The heat energy—and also the bio-oils and synthesis gases—generated during biochar production can be used to displace carbon positive energy from fossil fuels.
Biochar Cleaning the air
Biochar can clean the air in two ways;
- Preventing rotting biomass from releasing harmful CO2 into the atmosphere.
- Allowing plants to store the CO2 that they pull from the air via photosynthesis.
How can Biochar be carbon negative.
Fossil fuels are carbon positive; they add more carbon dioxide (CO2) and other greenhouse gasses to the air and thus exacerbate global warming. Ordinary biomass fuels are carbon neutral; the carbon captured in the biomass by photosynthesis would have eventually returned to the atmosphere through natural processes like decomposition. Sustainable biochar systems can be carbon negative by transforming the carbon in biomass into stable carbon structures in biochar which can remain sequestered in soils for hundreds and even thousands of years.
What is Carbon Sequestration
Carbon is found in all living organisms and is the major building block for life on Earth. Carbon exists in many forms, predominately as plant biomass, soil organic matter, and as the gas carbon dioxide (CO2) in the atmosphere and dissolved in seawater. Carbon sequestration is the long term storage of carbon in oceans, soils, vegetation (especially forests), and geologic formations. Although oceans store most of the Earth’s carbon, soils contain approximately 75% of the carbon pool on land — three times more than the amount stored in living plants and animals. Therefore, soils play a major role in maintaining a balanced global carbon cycle.
Over the past 150 years, the amount of carbon in the atmosphere has increased by 30%. Most scientists believe there is a direct relationship between increased levels of carbon dioxide in the atmosphere and rising global temperatures. One proposed method to reduce atmospheric carbon dioxide is to increase the global storage of carbon in soils.
Biochar and carbon sequestration
Slow pyrolysis biochars are highly recalcitrant in soils with half-lives of 100-900 years.Sensitivity analysis suggests that half lives of 80 years or more are sufficient to provide a credible C sink.Recent evidence using 14C-labeled biochar shows no evidence for enhanced rates of soil humic carbon degradation in agricultural soils.
- If biochar was used worldwide, CO2 levels could drop 8 parts per million within 50 years.
- CO2 levels in the air have been increasing at an alarming rate since the 1980’s.
- During the 1980’s carbon amounts were increasing at 1.5 ppm per year.
- Since 2000, carbon has been increasing 2 parts per million.
Creating a stable carbon pool with Biochar.
The Biofuel N2O Problem and how biochar avoid this issue
- Recent work (Crutzen et al., 2007, Atmos.Chem. Phys. 7:11191; Del Grosso, 2008, Eos 89:529) suggests that globally, N2O production averages at 4% (+/- 1%) of N that is fixed.
- IPCC reports have accounted only for field measurements of N2O emitted, which show values close to 1%, but ignore other indicators discussed by Crutzen et al.
- If 4% is correct, then combustion of biofuels except for high cellulose (low-N) fuels will actually increase global warming relative to petroleum due to large global warming potential of N2O
- Biochar avoids this issue
- Ties up reactive N in a stable pool.
- Eliminates potential N2O emissions from manures and other biomass sources converted to biochar.
- Decreases N2O emissions in field by improving N-fertilizer use efficiency and increasing air-filled porosity.
- Puts the earth back in the black
- Using biochar will not cause plants to grow in a new way. Rather, it helps the soil provide conditions more conducive to plant growth.
- Biochar’s constituents have a predictable role in the soil that enables conclusions about the benefits of biochar in specific growing situations.
- Biochar works in combination with other soil components and soil microbes to permanently improve the overall soil dynamics and plant nutrition, which in turn improves plant growth and yield.
- Biochar is made up of two portions. One portion is mobile, and includes biodegradable and leachable constituents. The other portion is resident: it is non-leachable and decomposes extremely slowly.
- The resident organic portion of biochar has unique internal structure and properties that give biochar its compelling benefits. This portion will remain in the soil, with beneficial amending impact, for a very long time—decades, centuries, and even millennia. Although conventional fertilizers may provide short-term benefits, they do not contribute to overall, long-term soil quality.
- Biochar is a natural material that has been deposited into soil by groundcover fires for billions of years. In its modern application, however, biochar can be manufactured and applied to improve soil fertility.
- Biochar thus offers substantial potential to the modern world for growing food sustainably, especially where soils are poor.
Written by : RAO ADEEL UR REHMAN ,ANDLEEB REHMAN,MUHAMMAD WASIM AKRAM
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