The cylindrical plastic plant-pot used in the experiment was 19 cm in diameter and 24
cm in height. Three kilograms of soil was mixed thoroughly
with an equivalent weight of BC and RS according to respective
treatments 20 days before transplanting the rice (-20 DAT;
day after planting). Five, twenty-five day old rice seedlings,
non-photosensitive Pathum Thani 1, were transplanted per
hill per plant-pot. Water-logging was maintained to give a
water depth of 5-7 cm above the soil surface until 27 DAT.
Thereafter, shallow flood water (0-7 cm) was controlled
throughout the growth period. Platinum (Pt) electrodes for
soil Eh measurement were installed at 4 cm distance from
the rice hill at 7 cm depth from the soil surface. Duplicate
measurements for each treatment were performed. CH4
emission rate, soil Eh and pH in the flood water were
measured throughout the rice growing season.