Globally wetlands appear as a significant source of Carbon Dioxide (CO2) emission. Rwanda is facing a new challenge of emission of CO2 gases from the rice fields and there is lack of sufficient data showing how it affects the environment. The objective of this paper is to estimate the CO2 gas emissions in different time of the day to determine maximum and minimum CO2 gas emissions from the rice field. An experiment was conducted to estimate the CO2 emission from the rice fields of Muvumba P-8 marshland. Gas collection chambers were installed in 9 plots to collect greenhouse gases. The gas samples were analyzed by Gas Chromatography. It was found that the mean CO2 gas emission for 6 am, 9 am, 12 Noon and 3 pm were 2001926, 2014388, 1827886 and 1957882 μg m-2 h-1. It was found that the CO2 gas emission is maximum at 9 am and minimum is at 12 Noon. And that mean CO2 gas emission varied among the 9 plots. The overall mean of CO2 gas emission among the 9 plots was 1950521 μg m-2 h-1 and its standard deviation was 271127. It was found that the CO2 gas emission at 6 am starts high and then linearly decreases up to 12 Noon there after the emission increases due to the ambient temperature rise. The interesting feature is the three trend lines of 6 am, 9 am and 12 Noon are almost coinciding at the same point with negligible differences of gas production. . The CO2 gas emission at 3 pm and 12 Noon are having similar behavior but the magnitude of gas production at 3 pm is higher than 12 Noon.

Keywords: Rice, Carbon dioxide, emission, marshland, Rwanda