The effect of microbial activity on soil water diffusivity.

B U Choudhury,D S Powlson,S Ferraris,W R Whalley,R W Ashton

doi:10.1111/ejss.12535

B U Choudhury, D S Powlson + Show 3 more

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https://doi.org/10.1111/ejss.12535

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Abstract

In this study, we explored the effects of microbial activity on the evaporation of water from cores of a sandy soil under laboratory conditions. We applied treatments to stimulate microbial activity by adding different amounts of synthetic analogue root exudates. For comparison, we used soil samples without synthetic root exudates as control and samples treated with mercuric chloride to suppress microbial activity. Our results suggest that increasing microbial activity reduces the rate of evaporation from soil. Estimated diffusivities in soil with the largest amounts of added root exudates were one third of those estimated in samples where microbial activity was suppressed by adding mercuric chloride. We discuss the effect of our results with respect to water uptake by roots.Highlights We explored effects of microbial activity on the evaporation of water from cores of a sandy soil.We found the effect of microbial activity on water release characteristic was small.Increasing microbial activity reduced evaporation from soil, while microbial suppression increased it.Effect of microbial activity on root water uptake was estimated to be equivalent to a change in soil structure.

Highlights

Microbial activity can greatly affect the structure and hydraulic properties of soil (e.g. Or et al, 2007; Colica et al, 2014; Helliwell et al, 2014)
We explored effects of microbial activity on the evaporation of water from cores of a sandy soil
The purpose of this study was to determine the effect of root exudates on soil water release curves and hydraulic conductivity over a wide range of soil water contents

Summary

Introduction

Microbial activity can greatly affect the structure and hydraulic properties of soil (e.g. Or et al, 2007; Colica et al, 2014; Helliwell et al, 2014). Microbial activity can greatly affect the structure and hydraulic properties of soil Incubation of soil with root exudates, either natural or synthetic, has been shown to reduce hydraulic conductivity in near-saturated soil (Hallett et al, 2003; Whalley et al, 2004). The study of Colica et al (2014) showed that induced biological crusts could reduce the rate of evaporation from dry soil. They found that the hydraulic conductivity of near-saturated soil depended on the molecular weight of carbohydrates added to soil; the hydraulic conductivity was less when higher-molecular-weight carbohydrates were added

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