Author(s): B. Kar, S. Karmakar, G. Saha and R. Bhattacharya

Abstract: The increasing demand of the growing population requires enhancement in the production of rice. This has a direct bearing on the global environment since the rice cultivation is one of the major contributors to the nitrous oxide (N2O) emissions. As the rice cultivation is intensified with the current practices and technologies, the nitrous oxide fluxes from paddy fields will substantially rise. Improved high yielding rice varieties together with efficient cultivation techniques will certainly contribute to the curtailment of the nitrous oxide emission. The effect of organic-fertilization on rice yield and their relationships with nitrous oxide fluxes as influenced by various weather factors was investigated taking various treatment as two dates of transplanting, two different aged seedlings for a most promising variety of Oryza sativa L. (Satabdi) under irrigated and rainfed condition. Trace gas fluxes from the soil were measured fortnightly throughout the entire growth period using a closed chamber method. Experimental results showed that N2O emission rate was highest for rainfed rice fields than irrigated ones especially after 30 and 60 days of transplanting. Canopy temperature and ambient temperature significantly affect the N2O emission rate. In case of irrigated system a positive correlation exists in between ambient temperature and N O emission after 30 and 60 DAT (R2= 0.98 and 0.31 respectively) but for rainfed condition the correlation was 0.45 and 0.33 only after 30 and 75 days after transplanting respectively. Another significant correlation was found in between canopy temperature and N2O emission from both water treatments as R2 = 0.35 and 0.38 for irrigated fields (30 and 60DAT respectively) and as R2 = 0.38 and 0.57 for rainfed fields (30 and 60 DAT respectively). These two climatic factors also affect the productivity of rice. Same trend of association was observed between N O emission potentiality and yield of rice where R2= 0.46 ( rainfed) and 0.17 ( irrigated) during 30DAT. So it is concluded that during organic rice cultivation atmospheric parameters plays pivotal role in N2O emission from rice field followed by productivity of rice...

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