Time-course of the soil microbial biomass under wheat: a one year field study
1994
Joergensen, R.G. | Meyer, B. | Mueller, T.
The fumigation-extraction (FE) method, applied after extraction of inorganic N and sieving was used to measure soil microbial biomass C, N and carbohydrate C contents at a depth of 0-10 cm under wheat every week in a field study lasting from October 1990 to November 1991. A minimum of 180 micrograms microbial biomass C g-1 soil and a maximum of 363 micrograms g-1 were recorded, the corresponding values for biomass N being 35 micrograms g-1 soil (= 53 kg ha-1) and 66 micrograms g-1 soil (= 99 kg ha-1). An increase was observed from December 1990 to November 1992, with minor fluctuations during periods with strong variations in weather conditions: cold and very wet in winter, extremely dry in summer. All three biomass components measured in the 0.5 M K2SO4 extracts of the FE procedure were significantly correlated. The intercepts of the linear relationships between microbial biomass C, N and carbohydrate C were non-significant, indicating constant component ratios. The amount of carbon additionally made extractable by fumigation consisted of 17% carbohydrate C. The biomass C:N ratio fluctuated closely around a mean value of 5.5.
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