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Fig. 3. Daily rates of CH4 production for lowland rice soils taken from four crop management treatments on the IRRI research farm. IRRI-1 is double-cropped rice with removal of aboveground crop residues and anaerobic decomposition of crop roots. IRRI-2 is double-cropped rice with anaerobic decomposition of all crop residues. IRRI-3 is double-cropped rice with aerobic decomposition of all crop residues. IRRI-4 is a rice-maize rotation with aerobic decomposition of all crop residues. The graph for the unamended control treatment shows production rates during a 70-d pre-incubation plus an additional 20 d that corresponded to the post-spiking incubation. Graphs for each of the four management treatments depict CH4 production during the 20-d incubation following spiking with glucose or root exudates compared to the unamended control. Units of the samplings from 0 to 24 h after spiking (inset graphs) are µg CH4 g –1 soil d–1. Vertical bars represent standard errors of three laboratory replicates. Abbreviations: DOI, days of incubation; DAS, days after spiking.
