Greenhouse gas flux monitoring in ecosystems is mostly conducted by closed chamber and eddy covariance techniques. To determine the relevance of the two methods in rice paddy fields at different growing stages, closed chamber (CC) and eddy covariance (EC) methods were used to measure the methane (CH₄) fluxes in a flooded rice paddy field. Intensive monitoring using the CC method was conducted at 30, 60 and 90 days after transplanting (DAT) and after harvest (AHV). An EC tower was installed at the centre of the experimental site to provide continuous measurements during the rice cropping season. The CC method resulted in CH₄ flux averages that were 58%, 81%, 94% and 57% higher than those measured by the EC method at 30, 60 and 90 DAT and after harvest (AHV), respectively. A footprint analysis showed that the area covered by the EC method in this study included non-homogeneous land use types. The different strengths and weaknesses of the CC and EC methods can complement each other, and the use of both methods together leads to a better understanding of CH₄ emissions from paddy fields.

The propose of this study was to evaluate CO2 flux and accumulative CO2 absorbance of the first ratoon cane by using Eddy Covariance Technique. First ratoon cane was produced at Cane and Sugar Industry Promotion Center, Kanchanaburi province, from June 2010 to April 2011. From the results, the CO2 flux was fluctuated from -2.4 to 2.8 mgCO2m-2s-1. The negative values showed in the day time and it means CO2 was absorbed by plant via photosynthesis. On the other hand the positive values means CO2 was emitted by plant and soil respiration in night time. Different CO2 flux was observed in each growth stages. CO2 flux was lower at germination stage (June 2010) and the total CO2 absorbance at this stage was 63.1 gCO2m-2. CO2 flux reached its maximum at stalk elongation stage (September 2010-January 2011) and total CO2 absorbance at this stage was 2,448.3 gCO2m-2. Totally, CO2 absorbance for the entire period of experiment was 4,300.4 gCO2m-2. Carbon use efficiency of the 1st ratoon cane was 2.13 tyield/tCO2. From the results, it was concluded that the 1st ratoon sugarcane ecosystem was a CO2 source during night hours and a CO2 sink during the day time. Finally, for the entire growing season the 1st ratoon cane system is the sink of CO2

The propose of this study is to evaluate water use of the first ratoon cane. First ratoon cane was produced at Cane and Sugar Industry Promotion Center Region 1 from June 2010 to April 2011. To evaluate crop water use Eddy Covariance technique was used. From the results, water use of first ratoon cane was gradually increased from predawn and reach the maximum during 12:00-14:00 and then water use was decreased. Moreover, water use in each growing stage were found. Minimum of water use average about 1.6 mmd-1 was found in germination stage, while maximum water use is 2.4 mmd-1 was found in stalk elongation stage. In addition, total water use germination stage, tillerling stage, stalk elongation stage and maturity stage was 57.3, 151.3, 330.6 and 142.7 mm, respectively. However, total water use of first ratoon cane was 682.1 mm. Water Use Efficiency of 1st ratoon cane was 0.012 tyield/tH2O. For this study we can concluded that water use of first ratoon cane depend on daily time and growing stage and total water use was 682.1 mm