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The
combustion of biomass leads to emission of methane and other trace
gases. In India,
about 60 per cent of households depend on traditional sources of
energy, like fuelwood,
dung cake and crop residue for meeting their cooking and heating needs
(Planning Commission, 2002). Using IPCC default emission coefficients,
the
amount of CH4 released in 1994 was 1,636 Gg. High uncertainties are
associated
with this estimate as biomass activity data are based only on small
surveys
carried out at different points of time. More exhaustive surveys are
required
to establish the quantity of various types of biomass used in the
country. [i]
The burning of crop residue is not a net source of CO2 as the CO2
released into
the atmosphere during burning is reabsorbed during the next growing
season.
However, burning of crop residue is a significant net source of CH4 in
addition
to other trace gases. The amount of agricultural waste produced by a
country
depends on its crop management system.
In
India, the primary
end-uses of crop residue are animal
fodder, industrial and domestic fuel, thatching, packaging, bedding,
construction of walls/fences, and as green-manure and compost. The
amount left
is what is available for field burning, and only a fraction of this
amount is
actually subject to burning. This fraction is, in fact, highly
uncertain and
varies with local and regional climate, season, livestock distribution,
availability of fuelwood, availability of fodder, weed infestation etc.
The
crop residue is particularly burnt in the rice/ wheat growing regions
of Punjab,
Haryana, Uttaranchal, western Uttar Pradesh and Karnataka, where with
the
introduction of mechanized harvesters, the collection and disposal of
residues
is a practical problem. Consequently, farmers prefer to burn residues
in the
field, primarily to clear the remaining straw and stubble after the
harvest and
to prepare the field for the next cropping cycle. Currently, wastes
from nine
crops viz., rice, wheat, cotton, maize, millet, sugarcane, jute,
rapeseed-mustard and groundnut, are subjected to burning. Thus, the
total dry
residue generation in the year 1994 was estimated to be about 203
thousand
tonnes. Using IPCC emission coefficients, the CH4 released from this
source was
found to be about 167 Gg. [ii]
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Bio-fuels
Agriculture
not only fulfills the food demand of the human beings but also other
demands such as that for energy from biofuel, clothes from cotton,
rubber from rubber and soon there will plastic grown as a crop. We know
that the fossil fuel is running out and it can not meet the growing
demand of human being for energy. Therefore, various experiments have
been carried out over the period of time to have an alternate fuel.
Crops are found to be reliable source of biofuels. Certain crops such
as Virgin oil feedstock, Jatropha, Mustard, Flax, Sunflower, Canola,
Palm, Hemp and citrus fruits etc. have been found to give
oil.
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