Global warming
is the increase in the average measured temperature
of the Earth's near-surface air and oceans
since the mid-twentieth century, and its projected
continuation. The average global air temperature
near the Earth's surface increased 0.74 ±
0.18 °C (1.33 ± 0.32 °F) during
the hundred years ending in 2005. The Intergovernmental
Panel on Climate Change (IPCC) concludes "most
of the observed increase in globally averaged
temperatures since the mid-twentieth century
is very likely due to the observed increase
in anthropogenic (man-made) greenhouse gas
concentrations" via an enhanced greenhouse
effect.
Apart from industries, agriculture
inevitably makes a contribution to greenhouse
gases, as does just about every human activity.
Currently it is responsible for 25% of the
world's carbon dioxide emissions, 60% of methane
gas emissions and 80% of nitrous oxide. The
main sources of green house gas emission are
methane from livestock, nitrous oxide from
agricultural soils, and carbon dioxide - mainly
from energy and fuel use, burning of agricultural
wastes etc. Importantly, these emissions often
also represent the loss of valuable resources
from farming systems - and therefore opportunities
for enhancing productivity.
In USA the staple crop is
corn and is cultivated in thousand and thousands
of hectares and after the harvest the stocks
are burnt in the field which is the major
source of CO2 emission. Thus there is drive
for sequestration of CO2 by burying the corn
stocks underground either in the deep sea
or in the land. The carbon sequestration could
be a costly solution and now scientists are
thinking an alternative for sequestration.
Conversion of crop residues in to bioethanol
could be a good alternative that has twin
advantages – reduces greenhouse gas
emissions, reduces the burden on fossil fuels.
In India the main crops cultivated
are paddy and wheat which does not have more
biomass as that of corn stocks and the straw
of these crops are harvested almost in its
entire from the field and used as the feed
for the livestock, the remaining crop residue
is ploughed back to the field and used as
biomass for the next crop. Thus the agricultural
waste is recycled effectively which does not
contribute much on greenhouse gas emissions.
Still there are some issues in greenhouse
gas emission from the agricultural land through
wetland paddy cultivation which account for
the major greenhouse gas emission, conventional
practice of agriculture etc that contributes
to the global warming.
Conservation tillage, a modern
agricultural method, uses the crop residues
and keeps the soil covered most of the time
all the way from planting through and beyond
harvest which is essential for its health,
productivity, and for retaining its organic
carbon content and can effectively mitigate
the current rate of increase of atmospheric
CO2 [carbon dioxide] concentration.
The views presented
here are generic in nature; however a detailed
study is necessary regarding contribution
of agriculture to global warming
