METHANE EMISSION FROM AN INDONESIAN PADDY FIELD SUBJECTED TO SEVERAL FERTILIZER TREATMENTS

Methane emission rates from a paddy field in Indonesia subjected to several fertilizer treatments were measured every week throughout the rice growing period. The mean CH4 emission rates (mg CH4 M-2 h-1) throughout whole growth period were in the ranges of 18.0-23.2 from chemical fertilizer plots and 19.5-27.1 from plots amended with both urea and organic materials. These rates were in the range of those reported from respective treatments in the temperate region. The effects of application of organic materials on the CH4 emission rates were less conspicuous than those of the reported results. The total CH4 emission (g CH4 m-2) throughout the growth period amounted to 31-40 from chemical fertilizer plots and 34-47 from plots amended with organic materials, respectively. Methane was mainly emitted in the first half of the growth period irrespective of treatments, which was in accordance with the results obtained in Thailand, and in contrast to those reported in the temperate region, where CH4 emission occurred mainly in the second half of the growth period.