Authors: Xu; Zhang; Liu

Source: European Journal of Soil Science, Volume 59, Number 4, August 2008 , pp. 630-639(10)

Publisher: Wiley-Blackwell

Abstract:

Summary

There is a need for a rapid, simple and reliable method of determining soil microbial biomass (SMB) for all soils because traditional methods are laborious. Earlier studies have reported that SMB-C and -N concentrations in grassland and arable soils can be estimated by measurement of UV absorbance in soil extracts. However, these previous studies focused on soils with small soil organic matter (SOM) contents, and there was no consideration of SOM content as a covariate to improve the estimation. In this study, using tropical and temperate forest soils with a wide range of total C (5-204 mg C g⁻¹ soil) and N (1-12 mg N g⁻¹ soil) contents and pH values (4.1-5.9), it was found that increase in UV absorbance of soil extracts at 280 nm (UV₂₈₀) after fumigation could account for 92-96% of the variance in estimates of the SMB-C and -N concentrations measured by chloroform fumigation and extraction (P < 0.001). The data were combined with those of earlier workers to calibrate UV-based regression models for all the soils, by taking into account their varying SOM content. The validation analysis of the calibration models indicated that the SMB-C and -N concentrations in the 0-5 cm forest soils simulated by using the increase in UV₂₈₀ and SOM could account for 86-93% of the variance in concentrations determined by chloroform fumigation and extraction (P < 0.001). The slope values of linear regression equations between measured and simulated values were 0.94 ± 0.03 and 0.94 ± 0.04, respectively, for the SMB-C and -N. However, simulation using the regression equations obtained by using only the data for forest profile soils gave less good agreement with measured values. Hence, the calibration models obtained by using the increase in UV₂₈₀ and SOM can give a rapid, simple and reliable method of determining SMB for all soils.

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1365-2389.2008.01015.x

Affiliations: 1: State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China

Publication date: 2008-08-01

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