Methane emissions from rice fields and its mitigation options by vinal vishal chand
Name: Vinal Vishal Chand
PROGAMME: Bsc Agriculture (ii) 2013
METHANE EMISSIONS FROM RICE
FIELDS AND ITS MITIGATION OPTIONS
The aim of this assignment was to find
out about Methane emissions from rice
fields and its mitigation options.
The increasing demand of the growing population requires
enhancement in the production of rice. This has a direct bearing on
the global environment since the rice cultivation is one of the major
contributors to the methane emissions.
As the rice cultivation is intensified with the current practices and
technologies, the methane fluxes from paddy fields is substantially
Improved high yielding rice varieties together with efficient cultivation
techniques will certainly contribute to the curtailment of the methane
Irrigated rice farming in paddy fields is an important source of CH4.
Methane is a chemical compound with the chemical formula CH4. It is
the simplest alkane and the main component of natural gas. The
relative abundance of methane makes it an attractive fuel.
Naturally occurring methane is mainly produced by the
process of methanogenesis. This multistep process which
is used by microorganisms as an energy source. The net
CO2 + 8 H+ + 8 e− → CH4 + 2 H2O
Methanogenesis is a form of anaerobic respiration used
by organisms that occupy landfill, ruminants (e.g., cattle),
and the guts of termites.
Rice agriculture is a big source of atmospheric methane,
possibly the biggest of man-made methane sources.
FLOODED RICE FIELDS
In flooded rice field, anaerobic decomposition of
organic material results in production of produces
This gas later escapes to the atmosphere primarily
by diffusive transport through the rice plants during
the growing season.
From the wide sources of atmospheric CH4, rice
paddy fields are considered one of the most
METHANE PRODUCTION PROCESSES
Flooded rice fields are a significant source of atmospheric
The emission is the net result of opposing bacterial
processes, production in anaerobic microenvironments,
and consumption and oxidation in aerobic
microenvironments, both of which can be found side by
side in flooded rice soils
The major pathways of CH4 (methane) production in
flooded soils are the reduction of CO2 (carbon dioxide)
with H2 (hydrogen).
CO2 + 4 H2 → CH4 + 2H2O
It is simply the formation of methane by microbes
This process is also called biomethanation
Application of fertilizer, especially organic manure
and submergence with deep water increased the
population and methanogenic activities of
methanogenic bacteria in rice soils.
This process is estimated to contribute about 25%
of the total budget of global methane emissions.
FACTORS AFFECTING METHANE
Water management or Water table
Harvesting and fallow period
EFFECT OF METHANE ON
Methane contributes to climate change. It is a potent contributor to
global warming due to its ability to trap warm air.
Methane have a major impact on world climate due to their
contribution to the greenhouse effect. CO2 is not only factor but
Methane also affects the degradation of the ozone layer.
Methane's lifetime in the atmosphere is much shorter than carbon
dioxide (CO2), but CH4 is more efficient at trapping radiation than
Methane is 23 times more potent than carbon dioxide in trapping
heat in our atmosphere.
Methane gas can seep into water supplies and contaminate
wells or surface water. Deaths have been caused by
exploding wells and by contaminated drinking water systems
poisoned by this odorless, tasteless gas.
Methane emissions can seep up through the ground and
cause problems for the environment and humans in
The emissions don't just propose a danger for flammability
but it also cause headaches and dizziness in humans as it
replaces the oxygen. This can result in suffocation.
When water containg methane mixes with ocean it directly
affects that climate and the life within that system.
When methane is involved in the process that moves carbon
into and out of vegetation zones that are climate and/or
weather dependent, it forces a change and directly affects
the vegetation growth and the life that requires that
vegetation to exist within that system.
MITIGATION OPTIONS FOR
Altering water management, in particular promoting
midseason aeration by short-term drainage, is one of the
most promising strategies, although these practices may be
limited to the rice paddy fields where the irrigation system is
This method reduce methane production.
Shifting drainage time from vegetative period to reproductive
period help reduce methane production and emission.
Shorten drainage day also help reduce methane emission.
REDUCE USE OF ORGANIC MATTER
Improving organic matter management by promoting
aerobic degradation through composting or
incorporating into soil during off-season drained period.
Reduce the use of organic matter or organic manure in
rice fields (wet lands).
Use inorganic fertilizer to increase the yields in wet
DRY LAND RICE CULTIVATION
Many rice varieties can be grown under much drier
conditions than those traditionally grown, with big
reductions on methane emission without any loss in
Additionally, there is the great potential for
improved varieties of rice, able to produce a much
larger crop per area of rice paddy and so allow for a
cut in the area of rice paddies, without a cut in rice
APPLICATION OF AMMONIUM
The addition of compounds such as ammonium
sulphate, which favours activity of other
microbial groups over that of the methanogens.
A SOIL CONDITIONER
Is a product which is added to soil to improve the soil’s physical
qualities, especially its ability to provide nutrition for plants.
It is category of soil Amendments which more often include a wide
range of fertilizers and non-organic materials.
Soil conditioners can be used to improve poor soils, or to rebuild
soils which have been damaged by improper management.
They can make poor soils more usable, and can be used to
maintain soils in peak condition.
A wide variety of materials have been described as soil conditioners
due to their ability to improve soil quality. Some examples include:
bone meal, peat, coffee grounds, compost, manure, straw,
vermiculite, sulfur, lime, blood meal, compost tea, hydroabsorbant
polymers and sphagnum moss.
To conclude, emission of methane from rice fields
are major problems in many country, it is mostly
due to organic matter present the fields.
However, mitigating CH4 emission from rice
paddy fields can not be fully controlled. However
it can be reduced. Some of the mitigation options
are water management (which is the most
important factor), soil amendments, organic
matter management, different tillage, crop
rotation, and cultivar selection.
Seiler, W., A. Holzapfel-Pschorn, R. Conrad, and D. Scharffe. 1984. Methane emission
from rice paddies.http://www.ipcc-nggip.iges.or.jp/public/gl/guidelin/ch4ref5.pdf
Wang Zhaoqian. 1986. Rice based systems in subtropical
Holzapfel-Pschorn, A., R. Conrad, and W. Seiler. 1985. Production, oxidation and
emission of methane in rice paddies. FEMS Microbiol. Ecol. 31: 343-