Methane production capacities of different rice soils derived from inherent and exogenous substrates

摘要: Methane production rates were determined at weekly intervals during anaerobic incubation of eleven Philippine rice soils. The average 25 °C varied in a large range from 0.03 to 13.6 μg CH4 g(d.w. soil) -1d-1. development methane derived inherent substrate allowed grouping soils three classes: those with instantaneous development, delay approximately two weeks, and suppression more than eight weeks. Incubation 30 35 increased capacities all soils, but the was still maintained. Arrhenius equation provided good fit for temperature effects on except suppressed production. Acetate amendment strongly enhanced disintegrated grouping. However, efficiencies converting acetate differed among Depending soil, 16.5–66.7% added utilized within five weeks °C. Correlation analyses (over weeks) physico-chemical soil parameters yielded significant correlations concentrations organic carbon (R2 = 0.42) nitrogen 0.52). indices could substantially be by using enriched fraction 0.94) 0.77), i.e. differential between topsoil subsoil respective compounds. material corresponds biologically active thus represents indicator substrate. best indicators conversion rate different pH-value 0.56) content Apparently, properties affect through various pathways. Inherent considerable source some is negligible others. Likewise, also differ regarding response exogenous Both mechanisms yield distinct spatial variability