Methane production potential of soils
1994
Lantin, R.S. | Aduna, J.B. | Alberto, M.C.R. | Neue, H.U. (International Rice Research Inst., Los Banos, Laguna (Philippines))
Soil properties govern the electrochemical and chemical changes which occur upon flooding and the pattern of CH4 formation. The effect of soil properties on CH4 production using 20 soils from different rice-growing areas in the Philippines was studied. Soils can be grouped into four classes according to the amount of CH4 produced during anaerobic incubation for 10 days (class 1 less than 1 microgram CH4/g soil; class 2 less than 10; class 3 to 100; class 4 more than 100). Each group has a distinct pattern of CH4 formation and differs significantly in the total amount of CH4 produced although final Eh and pH values were similar. Soil categorized under class 4 had the highest average OC content (2.2 percent) while those in classes 1-2 had average OC (1.4 percent). Soils with greater than 2 percent OC produced more than 300 microgram CH4/g. The OC content is the only soil property that shows a significant correlation with CH4 production. But CH4 production and soil OC are not correlated in soils with carbon content of less than 2 percent. Sandy soils high in OC produce more than CH4 than clay soils. With similar OC content, the negative impact of clay is probably due to the formation of ogranomineral complexes where carbon becomes less degradable. Clay soils may also entrap more CH4. The addition of rice straw increased CH4 production but did not affect the grouping of the CH4 production potential of the soils. This implies that degradable carbon is an important but not the only limiting factor for CH4 production. The effects of soil properties on CH4 production and oxidation are not well understood at present. Further research is needed to elucidate the dynamic and complex interaction of microbial metabolism of the whole fermentation chain and soil properties to determine mechanistically the CH4 production potentials of soils
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