Abstract

Global climate change is the primary important factor for agricultural production and one of the most urgent environmental problems. Agricultural soil is dynamic biological system that both stores and releases greenhouse gases. This makes soils an important source of greenhouse gases but also a potential sink if right management is applied. Climate change mitigation impacts arise largely from the stabilisation of soil organic matter, the reduction in fertilizer requirements and gaseous emissions in soils, and the production of renewable energy which can displace fossil fuel consumption. Biochar application may improve the soil health and reduce emissions from biomass that would otherwise naturally degrade to greenhouse gases. Converting biomass to biochar offers an excellent method for reducing waste and using these byproducts Biochar is one of the viable organic amendments to combat climate change and sustain the soil health with sustainable crop production. 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. Biochar application may improve the physical, chemical and biological properties of soils, reduce fertilizer requirements and stimulate plant growth, though the results vary between biochars, soil types and plant species. The effectiveness of biochar for the improvement of soil properties is influenced by the biomass feedstock and the pyrolysis conditions Biochar also has appreciable carbon sequestration value.
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Biochar for future food security
Climate is an important factor of agricultural
productivity. Climate change is caused by the release of
‘greenhouse gases into the atmosphere. Agriculture
produces CO2, CH4 and N2O which is directly or indirectly
due to the burning of non-renewable resources (carbon
bound in mineral oil or coal). While CO2 is the primary
gas emitted by most other industries, the primary
greenhouse gases emitted by agriculture are CH4 and N2O.
Agriculture contributes to over 20 per cent of global
anthropogenic greenhouse gas emissions. The change in
temperature and rainfall patterns is also damaging the
organic matter, physical structure and the populations of
soil organisms. The large increase in the use of nitrogen
fertilizer for the production of crops has dramatically
increased the emissions of nitrous oxide, a powerful
greenhouse gas, while the gasoline and diesel fuel that is
consumed by tractors and trucks is also a large source of
carbon emissions. Soils contain 3.3 times more carbon
than the atmosphere and 4.5 times more than plants and
animals on earth. This makes soils an important source of
greenhouse gases but also a major sinks and helps to
sequester more carbon and cut the N2O emission by
adopting right soil and crop management techniques.
The world population is currently increasing at a fast rate
and is expected to reach 9 billion by 2050. To meet a
growing demand for food from a growing population, we
need to increase agricultural productivity upto 70 per cent,
and food production in the developing world will need to
Biochar for future food security: An overview
Vikas Abrol, Peeyush Sharma and Vishaw Vikas
Division of Soil Science and Agricultural Chemistry, ACRA (SKUAST-J), Rakh Dhiansar,
JAMMU (J&K) INDIA
Volume 12 Issue 1 June, 2017 95-97RASHTRIYA KRISHI
Global climate change is the primary important factor for agricultural production and one of the most urgent environmental
problems. Agricultural soil is dynamic biological system that both stores and releases greenhouse gases. This makes soils an
important source of greenhouse gases but also a potential sink if right management is applied. Climate change mitigation
impacts arise largely from the stabilisation of soil organic matter, the reduction in fertilizer requirements and gaseous emissions
in soils, and the production of renewable energy which can displace fossil fuel consumption. Biochar application may improve
the soil health and reduce emissions from biomass that would otherwise naturally degrade to greenhouse gases. Converting
biomass to biochar offers an excellent method for reducing waste and using these byproducts
Biochar is one of the viable organic amendments to combat climate change and sustain the soil health with sustainable
crop production. 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. Biochar application may improve the physical, chemical and biological properties of soils, reduce fertilizer requirements
and stimulate plant growth, though the results vary between biochars, soil types and plant species. The effectiveness of
biochar for the improvement of soil properties is influenced by the biomass feedstock and the pyrolysis conditions Biochar
also has appreciable carbon sequestration value.
double by 2050 (FAO). In recent years biochar
application gained momentum because of its unique ability
to help build soil, improves soil physical condition,
enhancing nutrient uptake from the soil and to reduce
nitrous oxide emission and sequester carbon.
Biochar : Biochar is a solid material produced by a
thermochemical decomposition process. This process is
called pyrolysis, which consists of heating biomass at a
high temperature (400 8000C) in a limited oxygen
environment. Pyrolysis is the chemical decomposition of
an organic substance by heating in the absence of oxygen.
The word is derived from Greek word ‘pyro’ meaning
fire and “lysis” meaning decomposition or breaking down
into constituent parts. Biochar first came into broad public
awareness through the example of the Amazon, where
the hypothesis is that Amazonian inhabitants added biochar
along with other organic and household wastes over
centuries to modify the surface soil horizon into a highly
productive and fertile soil called terra preta (dark earth),
which is in direct contrast to the typical weathered Oxisol
soils in close proximity. Biochar, also known as black
carbon, is a product derived from organic materials rich
in carbon (C) and is found in soils in very stable solid
forms, often as deposits. Biochar, a soil amendment, has
potential as a valuable tool for the agricultural industry
with its unique ability to help build soil, conserve water,
produce renewable energy and sequester carbon. Biochar
can be created from a wide variety of feedstocks (as
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VIKASABROL, PEEYUSH SHARMA AND VISHAW VIKAS
straw, nut shells, rice hulls, wood chips, wood pellets, tree
bark and manure). Studies sponsored by the Ministry of
New and Renewable Energy (MNRE), Govt. of India
have estimated surplus biomass availability (Fig. 1).
Feedstock, along with pyrolysis conditions, the most
important factor controlling the properties of the resulting
biochar. Rice husk and rice straw contain unusually high
levels of silica (220 and 170 g kg-1) compared to that in
other major crops. As a soil amendment, biochar
significantly increases the efficiency of and reduces the
need for traditional chemical fertilizers, while greatly
enhancing crop yields. The carbon in biochar resists
degradation and can hold carbon in soils for hundreds to
thousands of years.
Fig. 1 : Residue generation by different crops in India
(calculated from MNRE, 2009)
How is biochar made ? :
Material required:
Metal container : Needs to be tight-closing and
sturdy as it will be acting as ‘biochar cooker’.
Organic material for charring : Leaves,
Twigs, wood chips , manure etc
Fire place/pit/drum : A drum or pit will work
better as it uses less fuel and creates greater heat
intensity- charring quicker and better.
Stemps :
Tight-fitting containers, which are essential, but
there should be “escape holes” because under extreme
heat the pressure inside the containers would potentially
force them to explode.
Although the fire in drum takes longer to create
glowing embers (due to less oxygen exposure than an
open fire), the heat intensity is eventually far greater and
also uses less fuel for it.
Depending on the container, woods used, heat
intensity of fire etc., the time to char will be variable.
Notice a plume of what looks like smoke coming from the
hole in the container- this is actually the gases of the wood.
Once cooled, check charring is consistent all the
way throug., keep them in a tight container and
somewhere dry until use
Impacts on soil : Soil carbon levels have decreased under
agricultural land use. Research revealed that minimum or
no-tillage practices, mixed farming with manure
amendment leads to higher organic matter levels in soil.
Soil is a part of the natural world that is both affected by
and contributing to global warming. Soil is the one of the
largest sources of carbon in the world. It is primarily
accumulated through plants which ‘fix’ the carbon from
carbon dioxide in the air; the soil then directly absorbs the
carbon as the plants decay. Additionally, dead leaves and
animals are broken down by microbes in the soil and carbon
is accumulated. 2.2 gigatons of C can be stored in the soil
by 2050 using biochar conversion technologies, according
to the International Biochar Initiative (http://
www.biochar-international.org/biochar). Biochar is
highly porous, thus the addition of soil is considered to
improve a range of soil physical properties including total
porosity, pore-size distribution, soil density, water holding
capacity or plant available water content, and infiltration.
Biochar can retain applied fertilizer and nutrients and
release them to agronomic crops over time. Biochars’
ability to retain water and nutrients in the surface soil
horizons for long periods benefits agriculture by reducing
nutrients leaching from the crop root zone, potentially
improving crop yields, and reducing fertilizer requirements.
Additionally, biochar could improve food production in the
world’s poorest regions as it increases soil fertility.
Impact on climate change : In addition to agronomic
benefits there is a great interest in the climate change
mitigation potential of biochar as its capability to sequester
soil carbon over a long time. Under normal circumstances
CO2 is removed from the atmosphere by photosynthesis
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and added to the soil in the form of organic matter, then
as the organic matter decomposes CO2is released back
into the atmosphere though microbial respiration. The
pyrolysis of organic matter results in a form of carbon
with an altered chemical structure (aromatic C rings) that
is resistant to microbial decomposition, called recalcitrant
or fixed carbon. When added to the soil this carbon is not
readily decomposed and hence carbon remains in the soil
and out of the atmosphere. This means that biochar allows
carbon input into soil to be increased greatly compared to
the carbon output through soil microbial respiration, and it
is this that is the basis behind bio char’s possible carbon
negativity and hence its potential for climate change
mitigation. According to a new study, as much as 12 per
cent of the world’s human-caused greenhouse gas
emissions could be sustainably offset by producing biochar.
One tonne of biochar is equivalent to 2.7 tonnes of carbon
dioxide removed from the atmosphere. The World Bank
has identified biochar as the most effective system of
greenhouse gas abatement in soil when compared to all
other sustainable land management practices.
The list of potential gains from applying biochar to
soils that are reported in the literature is almost endless:
Increased yields of up to a doubling
Increased fertilizer efficiency
Increased water retention
Mitigation of climate change due to the
sequestration of carbon in a resistant form, the reduction
of the emissions of the potent greenhouse gases nitrous
oxide and methane, production of renewable energy, etc.
Fig. 2 : Input , process, output, applications and impacts on global warming (Image: Nature Material)
Disposal of green waste from agriculture and
forestry
Increased cation exchange capacity of the soil
Biochar is extremely porous which allows it to
retain nutrients and water — which plant roots can access
when the biochar is added to soil.
Increased soil pH (i.e. less acidic)
Increased soil microbial biomass
www.biochar-international.org
Received : 24.01.2017 Revised : 06.05.2017 Accepted : 16.05.2017
BIOCHAR FOR FUTURE FOOD SECURITY:AN OVERVIEW
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