Microbiological parameters as indicators of soil organic carbon dynamics in relation to different land use management
2010
Llorente, Mireia | Turrión, M Belén
Labile C fractions: microbial biomass C (MBC), K₂SO₄ extractable C ([Formula: see text]) and the cumulated mineralized C in 21 days incubation at 28°C (C–CO₂₍₂₁d₎), were compared as land use indicators in a calcareous soil under three different management systems: native Querqus ilex forest (under and outside tree cover), a Pinus halepensis plantation, and cropped land (with cereals). Microbial biomass and activity were found to be low and coincided with high carbonate contents. As indicators of land use, [Formula: see text] and C–CO₂₍₂₁d₎ showed the same sensitivity as MBC. C–CO₂ emissions were measured in an incubation experiment in order to study C mineralization kinetics. The data for cumulative amounts of C–CO₂ released showed a good fit (R ² > 0.94) to the first-order kinetic model C ₘ = C ₒ(1 − e⁻ᵏᵗ). The kinetic parameters C ₒ and C ₒ k were affected by land use and especially by tree cover. Principal components analysis was applied to the data and the relationship among microbial metabolic quotient (qCO₂), labile C pools, and MBC revealed a decrease in efficiency of organic substrate utilization with an increase in availability and lability of the organic matter.
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