Agriculture Reference
In-Depth Information
Fig. 3.5
Results of multi-
dimensional regression
analysis between plant
conductance for methane
and physical parameters;
Regressed value R = 0.793
(
p
< 0.01). (Source: Yao et al.
2000
)
[
5RRWYROXPH
OHQJWKRIURRWEXQGOH
5
UHJUHVVHG;
with root volume (Fig.
3.5
). Jones (
1992
) reported that the size of the micro-pores,
the size of the inter-cellular space and plant conductance are proportional to the size
of the rice plant.
9 Conclusion
The agricultural sector contributed 47 % of total CH
4
emissions in the year 2005
(IPCC-AR4
2007
) and South and East Asia was the major contributor (82 % of total
CH
4
emissions) because of widespread rice cultivation in the region. Many agricul-
tural scientists, who have carried out various studies, recommended various mea-
sures for reducing CH
4
emission from the rice fields. CH
4
emission from rice fields
is strongly influenced by existing water regime, local crop management practices,
cropping rotation and quality of organic inputs used. Practice of no tillage system
and cultivation of perennial crops can significantly reduce CH
4
emissions from soil
by increasing soil C storage. In upland farming, direct seeded rice cultivation and
'No Tillage' system are two promising options for reducing methane emissions from
cultivated rice fields. Use of prilled urea, urea-super-granule, and application of
nitrification inhibitor (Nimin) can reduce CH
4
emissions effectively. Management
of organic matter, application of organic matter during off-season drained period,
application of biogas-slurry to the rice fields are some of the variants of measures to
reduce GWP of rice soil. P deficiency in rice soil leads to increase in root exudates
amount by lowering the membrane permeability and enhancement of downward
transfer of O
2
and upward transport of CH
4
, thus management of Phosphorous (P)
availability in rice soil would be a viable option for reducing CH
4
emission.
Emission of CH
4
through the rice plants is influenced by various properties of
the plant itself, i.e., photosynthate allocation capacity, root volume, oxidase activity
in the vicinity of root tip, amount and nature of root exudates, properties of aeren-
chyma tissue, number and structure of nodes, stages of crop growth and methane
