Methane Emission and Its Affected Factors in Eastern Taiwan Paddy

Experimental paddy fields were set to measure the rate of methane emission in eastern Taiwan with calcareous schist alluvial soil (Chian)and non-calcareous schist mixed slate alluvial soil(Fuli)in 2nd crop, 1994 to 1st crop, 1996 of rise. Experimental treatments were with or without straw incorporated (Chian trial), N-fertilizer high and low rates(Fuli trial), respectively. The results showed that the amount of methane emitted from 2nd crop of rice in 1994 and 1995 were 90 and 809 μg CH_4/hr. m^2, and 1st crop in 1995 and 1996 were 832 and 494 μg CH_4/hr. m^2, respectively, at Chian trial, whereas the amount from 2nd crop in 1994 and 1995 were 7,481 and 16,795 μg CH_4/hr. m^2, and 1st crop in 1995 and 1996 were 4,029 and 6,851 μg CH_4/hr. m^2, respectively, at Fuli trial. The straw incorporation affected production and emission of methane significantly, and increasing the amount of methane was in the range of 18.9%∼1,106.7%(average 361.6%). The treatment of high rate N-fertilzer addition promoted the amount of methane emission, it's range of methane was 50.6%∼99.1%(average 69.7%) increased. The rates of methane emission were highly effected by climatic and soil factors. Methane emission were increased simultaneously when the temperature of air, water and soil were uprising.