Soil Microbial Biomass Carbon

An essential and very important component of soil organic matter is the soil microbial biomass which regulates the transformation and storage of nutrients. Since soil micro-organism play a significant role in the retention and release of nutrients, the role of soil microbial biomass must be taken into consideration in any attempt to assess nutrient and energy transfer within soil system. 

Weight of soil (oven dry weight equivalent) taken for microbial biomass measurement (Ws). 

Volume of KoCroOy (2 ml) x Strength of KoCroOY Strength of FAS (N) =---------Mean titre value for blank (ml)---- 

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Fig. 2. Effect of Pb (a) and Cd (b) on the dynamics of soil microbial biomass carbon (Cniic) (from Akmal et al. 2005a).

Table 2. Effect of Pb and Cd interaction on soil microbial biomass carbon (mg kg-1) (DAA represents days after heavy metal addition different letters within column indicate that treatment means are significantly different at P < 0.01) (Authors unpublished data, 2006)...

Follow the steps (1-15) in article no. 3.6 in the determination of soil microbial biomass carbon. 

The present text book is a comprehensive analytical manual covering the aspects of soil analysis in the major areas of Soil Physics and Soil Chemistry. Furthermore, the concept of soil microbial biomass carbon and nitrogen is also dealt in detail. An important feature of this text is that it describes not only the analytical procedures in detail but also furnishes sufficient theoretical background on the subject matter. The fundamental principles of the analytical methods have been discussed precisely and the theories explained well with mathematical analysis and chemical reactions whenever required. 

Kouno et al. (2002) estimated the turnover times of soil microbial biomass carbon and phosphorus by following decreases in biomass and P following the addition to soil of C-labelled glucose and KH PO, or of ryegrass which had been double... 

Buchanan, M. and King, L.D. (1992) Seasonal fluctuations in soil microbial biomass carbon, phosphorus, and activity in no-till and reduced-chemical-input maize agroecosystems. Biology and Fertility of Soils 13, 211-217. 

U. Schenk, R. Manderschied, J. Hugen, and H.-J. Weigel, Effects of CO, enrichment and intraspecific competition on biomass partitioning, nitrogen content and microbial biomass carbon in soil of perennial ryegrass and white clover, J. Exp. Bot. 46 987 (1995). 

D. A. Wardle, A comparative assessment of factors which influence microbial biomass carbon and nitrogen levels in soil, Biol. Rev. 67 321 (1992). 

He ZL, Wu J, O Donnell AG, Syers JK (1997) Seasonal responses in microbial biomass carbon, phosphorus and sulphur in soils under pasture. Biol Fertil Soils 24 421 128... 

Sparling GP (1992) Ratio of microbial biomass carbon to soil organic carbon as a sensitive indicator of changes in soil organic matter. Aust J Soil Res 30 195- 207... 

Keywords Organic farming Biodiversity Climate change C02 Soil carbon N20 Methane Soil microbial biomass Erosion Food quality... 

Microbial biomass carbon Chloroform fumigation incubation Indicates soil microbial population various methodologies controls nutrient cycling and biological transformation necessary for soil aggregation dependent upon organic inputs Rice et al. (1996)... 

Rice CW, Moorman TB, Beare M (1996) Role of Microbial Biomass Carbon and Nitrogen in Soil Quality. SSSA Special Pub 49 203-216... 

Dar, G.H. Impact of lead and sewage sludge on soil microbial biomass and carbon and nitrogen mineralization. B. Environ. Contam. Tox. 1997, 58, 234-240. 

Breland, T.A. and Eltun, R. 1999. Soil microbial biomass and mineralization of carbon and nitrogen in ecological, integrated and conventional forage and arable cropping systems. Biology and Fertility of Soils 30 193-201. 

Jenkinson, D. S. (1988). Determination of microbial biomass carbon and nitrogen in soil. In Advances in Nitrogen cycling in Agricultural Ecosystems. Commonwealth Agricultural Bureau International, Wallingford, UK, pp. 368-386. 

The weight of soil used in the measurement depends on the initial soil microbial biomass concentration and the flask volume. Normally, 20-40 g moist soil is suitable for this measurement. Lin and Brookes (1999a) showed that SIR can give reliable estimates of microbial biomass in unamended soils, soils that contain actively decomposing plant residues, or soils recently treated with pesticides or fumigants. The final results are usually expressed as the SIR rate (tl C02 evolved g soil h Biomass carbon (Bc) is estimated by Bc (gig C g l soil) = 15 SIR (Lin and Brookes 1999a). 

Nicolardot B., Fauvet G., and Cheneby D. (1994) Carbon and nitrogen cychng through soil microbial biomass at various temperatures. Soil Biol. Biochem. 26(2), 253 —261. 

Lu Y., Watanabe A., and Kimura M. (2002) Contribution of plant-derived carbon to soil microbial biomass dynamics in a paddy rice microcosm. Biol. Fertility Soils 36, 136-142. 

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