EFFECT OF RICE VARIETY ON METHANE EMISSION FROM AN INDONESIAN PADDY FIELD

Variations in CH4 emission from a Sumatra paddy held in which 8 popula r modern varieties in Indonesia were grown were compared in the 1994/1 995 rainy season. Total amounts of CH4 emitted during the period of ri ce growth were in the ranges of 32.6-41.7 and 51.3-64.6 g CH4 m(-2) fo r the plots amended with chemical fertilizer only and those amended wi th both rice straw-and chemical fertilizer, respectively. The mean CH4 emission rate was highest in the plot with the variety Bengawan solo and lowest in the plots with the varieties Atomita-4 and Way seputih a mong the plots which received chemical fertilizer, while highest in th e plot with Way seputih and lowest in the plot with Bengawan solo amon g the plots amended With both rice straw and chemical fertilizer. The increase in the mean CH4 emission rates by rice straw application was higher for the plots planted with Way seputih (1.98 times) and Atomita -6 (1.77 times) than for the plots with Bengawan solo (1.23 times) and IR-64 (1.35 times). The plots with Walanai and Cisanggarung recorded intermediate mean emission rates and the increase in CH4 emission by r ice straw application was also intermediate (1.57-1.64 times). It was noteworthy that Way seputih and Atomita-4 were derived from the variet y Cisadane, Bengawan solo and IR-64 from the variety IR-54, and Walana i and Cisanggarung from the varieties IR-36 and Pelita 1-1, respective ly. The amounts of CH4 emitted for 1 kg grain production ranged from 5 3 (Atomita-4) to 74 (Kapuas and Walanai) and from 89-93 (IR-64, Bengaw an solo, and Atomita-4) to 121 (Kapuas) g CH4 kg(-1) of grain for the plots amended with chemical fertilizer and those amended with rice str aw and chemical fertilizer, respectively.