Abstract

A study on the effect of organic fertilizer (cow manure) on carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) emissions in a paddy field was conducted. Suphanburi 1 rice varieties were planted in a double-crop organic rice field at Pathum Thani Rice Research Center, Pathum Thani Province, Thailand. The study was categorized into 4 sets of experiments as follows: 1) control, without added fertilizer, 2) addition of organic fertilizer (cow manure) at 3.13 t·ha^-1, 3) addition of organic fertilizer at 9.38 t·ha^-1 and 4) addition of organic fertilizer at 12.50 t·ha^-1. The study showed that the set with the addition of organic fertilizer at 12.50 t·ha^-1 had the highest emissions rate of methane at an average rate of 4.94 mg·m^-2 d. Lower methane emissions were found in the sets with added organic fertilizer at 9.38 t·ha^-1 and in the control set without added fertilizer and the set with added organic fertilizer at 3.13 t·ha^-1, with an average emission rate of 3.08, 1.77 and 1.49 mg·m^-2·d, respectively. The differences in the methane emissions of all of the sets are statistically significant, (P<0.05). Compared to the other sets, the carbon dioxide emissions were highest in the set with added organic fertilizer at 9.38 t·ha^-1, at an average rate of 380.55 mg·m^-2·d. The rates were lower in the set with added organic fertilizer at 3.13 t·ha^-1, the control set without added fertilizer, and the set with the addition of organic fertilizer at 12.50 t·ha^-1, with emission rates of 325.24, 253.92 and 198.16 mg·m^-2 d, respectively. However, these results had no significant difference. Meanwhile, the nitrous oxide emissions during the growing season of the rice were the highest in the set with the addition of organic fertilizer at 9.38 t·ha^-1, which had an average rate of 1.41 mg·m^-2·d. The rate was lower in the control set without added fertilizer, the set with added organic fertilizer at 3.13 t·ha^-1, and the set with added organic fertilizer at 12.50 t·ha^-1 with average emissions rates of 1.10, 1.40 and 0.60 mg·m^-2·d, respectively.

 

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