Abstract:
The concentration of Methane in Earth's atmosphere is reported
to be inoreasing on the basis of the results obtained by means of
a variety of independent measurements attributed to the emission
from rice growing regions. To understand the global budget of
atmospheric methane, intensive research on individual methane
sources are required to be investigated and integrated for arriving
at a definite conclusion. Attempts have, therefore, been made for
measuring methane emission from different rice fields of different
places in Bangladesh. Methene emission observed were of highest
magnitude in the last 2-3 weeks before harvest. Hourly emissions
have been observed to be 27.21 mg. m"2hr_1 and the emissions have
been found to vary with the paddy varieties, geographical location,
soil group, soil texture and structure, soil temperature, soil pH,
ambient temperature and various other factors.Effect of different
parameters on methane effluxes have been discussed. A correlation
of plant growth on methane emissions has been formulated.
In order to study the mitigation measures for the suppression
or reduction of methane emission from the rice fields,
investigations with the natural pesticides were carried out in the
laboratory and then applied in the field experiments. For this
purpose the extracts of Neem tree components (Azadirachta Indica)
and some metalcomplexes of the extracted components were used.
Petroleum ether, EtOAc, MeOH and also aqueous extracts of
AZADIRACHTA INDICA leaf showed insecticidal effect towards house
flies while petroleum ether extract exhibited only repelling effect
against mosquitoes and insecticidal effect on lice. Attempts were
made to effect complexation of the extracts with metal ions like
Ni(II), Cu(II) and Zn(II) and the extracts were subjected to
chromatography to yield a number of compounds. The IR spectral data
of these compounds have been discussed. In the laboratory
experiments the extracts was found to be effective
