Measurement of methane emissions from a rice field using manual headspace sampling in closed chambers
2011
Llorente, C. | Wassmann, R. | Padre, A., International Rice Research Inst., Los Banos, Laguna (Philippines) | Solivas, J., Philippines Univ. Los Baños, College, Laguna 4031 (Philippines)
Methane (CH4) emission rates were determined using closed chamber method. Gas samples were collected using transparent chambers with 60 cm x 60 cm base and 122.5 cm height during a 10-minute interval for 30 min. The set up which included four chambers collected gas samples during 9:00 AM and 2:00 PM based on the completed preliminary experiments. The gas samples were analyzed using Shimadzu Gas Chromatograph equipped with Flame Ionization Detector. Preliminary tests were conducted on the chambers and syringes to ensure that there will be no or at least negligible losses on the sample during handling from the field to the laboratory. Also a separate preliminary test was done to determine the optimum sampling time. Statistical analysis using Wilk-Shaphiro test showed that the emission rates in the morning and afternoon readings are the same. Statistical analysis at alpha=0.05 showed that there is a significant difference between the morning and the afternoon readings. Generally, the afternoon readings were relatively higher compared to that of the morning readings.
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