Utilization of organic materials in soil aggregates by bacteria and fungi

Effect of organic and mineral amendments upon soil respiration and microbial biomass in a saline-sodic soil

“…M t C was highest in the control (T0), whereas M b C was lower in treatment T5. The control also showed the highest M b C. Clearly, the organic and mineral amendments decreased soil salinity, while the control (T0) most likely reflected a shift in population structure to one dominated by less active microorganisms, mainly fungi, with lower respiration rates compared to a population dominated by more active microorganisms, mainly bacteria (Adu and Oades, 1978;Sadinha et al, 2003). Our results are similar to those found by Wong et al (2008).…”

Bacterial and Fungal Contributions to Carbon Sequestration in Agroecosystems

“…These observations have been taken as indirect evidence to support the concept that soil fungi are more efficient than bacteria in their utilization of substrate. This paradigm has a strong hold in soil ecology (e.g., Alexander, 1977;Holland and Coleman, 1987;Rillig et al, 1999;Zak et al, 1996); however, there are equally plausible alter- Lindeberg and Lindeberg, 1977 0.30-0.40 Payne and Wiebe, 1978 ‡ 0.04-0.85 Lekkerkerk et al, 1990 0.10-0.26 Schrickx et al, 1993 0.53-0.62 Baroglio et al, 2000 0.05-0.57 Aquatic systems del Giorgio and Cole, 1998 0.01-0.60 Suberkropp, 1991 0.15-0.23 Søndergaard et al, 2000 0.43 Rivkin and Legendre, 2001 § 0.10-0.70 Sterile soil inoculated with a single organism Anderson et al, 1981 0.60 Elliott et al, 1983 0.61 Non-sterile soil with a mixed population Shields et al, 1973 0.63 Behera and Wagner, 1974 0.39 Adu and Oades, 1978a 0.58 Anderson and Domsch, 1986 0.37-0. 53 Schimel, 1988 ¶ 0.25-0.59 Parsons and Smith, 1989 0.54-0.73 Ladd et al, 1992 0.50-0.77 Bremer and Kuikman, 1994 0.58-0.70 Hart et al, 1994 ¶ 0.14-0.60 Shen and Bartha, 1996 0.47-0.66 Dahlin and Witter, 1998 0.45-0.53 Frey et al, 2001 0.26-0.68 Lundberg et al, 2001 0.60-0.74 † No data or citations are presented and it is unclear as to the growth conditions under which these yield values were obtained.…”

Relationship of soil organic matter dynamics to physical protection and tillage

“…Evidence of the physical sequestration of organics in very small pores presumably inaccessible to microorganisms comes from microscopic observations (Kilbertus, 1980;Foster, 1981). On the other hand, experimental studies based on model systems have shown that the extent and kinetics of biodegradation were controlled by the ability of the substrate to diffuse to the cell (Adu and Oades, 1978;Barlett and Doner, 1988;Scow and Alexander, 1992). In the soil matrix, diffusion is limited by the pores geometry and by the continuity and tortuosity of diffusion pathways.…”