Authors: Vanessa N L Wong Ram C Dalal Richard S B Greene
Publish Date: 2008/04/02
Volume: 44, Issue: 7, Pages: 943-953
Abstract
An understanding of the effects of salinity and sodicity on soil carbon C stocks and fluxes is critical in environmental management as the areal extents of salinity and sodicity are predicted to increase The effects of salinity and sodicity on the soil microbial biomass SMB and soil respiration were assessed over 12weeks under controlled conditions by subjecting disturbed soil samples from a vegetated soil profile to leaching with one of six salt solutions a combination of lowsalinity 05dSm−1 midsalinity 10dSm−1 or highsalinity 30dSm−1 with either lowsodicity sodium adsorption ratio SAR 1 or highsodicity SAR 30 to give six treatments control lowsalinity lowsodicity lowsalinity highsodicity midsalinity lowsodicity midsalinity highsodicity highsalinity lowsodicity and highsalinity highsodicity Soil respiration rate was highest 56–80mg CO2C kg−1 soil in the lowsalinity treatments and lowest 1–5mg CO2C kg−1 soil in the midsalinity treatments while the SMB was highest in the highsalinity treatments 459–565mg kg−1 soil and lowest in the lowsalinity treatments 158–172mg kg−1 soil This was attributed to increased substrate availability with high salt concentrations through either increased dispersion of soil aggregates or dissolution or hydrolysis of soil organic matter which may offset some of the stresses placed on the microbial population from high salt concentrations The apparent disparity in trends in respiration and the SMB may be due to an induced shift in the microbial population from one dominated by more active microorganisms to one dominated by less active microorganismsThe authors would like to acknowledge the Cooperative Research Centre for Greenhouse Accounting and the Cooperative Research Centre for Landscape Environments and Mineral Exploration for funding S Chin Wong and Linda McMorrow for assistance in the laboratory David Little for assistance in the field Weijin Wang Sue Welch and the two anonymous reviewers for comments on the manuscript and Eric Dowling for access to his property
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