You are not logged in.
Openly accessible

Investigation of compounds causing water repellency in the rhizosphere of sandy soils from a wide range of locations.

Doerr, S. H., Llewellyn, C. T., Douglas, P., Morley, C. P., Haskins, C., Johnsey, L., Ritsema, C. J., Stagnitti, Frank and Ferreira, A. J. D. 2002, Investigation of compounds causing water repellency in the rhizosphere of sandy soils from a wide range of locations., in WCSS 2002 : 17th World Congress of Soil Science : 14-21 August 2002, Bangkok, Thailand. Keynote lectures, Kasetsart University, Bangkok, Thailand, pp. 1-11.

Attached Files
Name Description MIMEType Size Downloads
stagnitti-investigationofcompounds-2002.pdf Published version application/pdf 176.11KB 284

Title Investigation of compounds causing water repellency in the rhizosphere of sandy soils from a wide range of locations.
Author(s) Doerr, S. H.
Llewellyn, C. T.
Douglas, P.
Morley, C. P.
Haskins, C.
Johnsey, L.
Ritsema, C. J.
Stagnitti, Frank
Ferreira, A. J. D.
Conference name World Congress of Soil Science (17th : 2002 : Bangkok, Thailand)
Conference location Bangkok, Thailand
Conference dates 14 - 20 August 2002
Title of proceedings WCSS 2002 : 17th World Congress of Soil Science : 14-21 August 2002, Bangkok, Thailand. Keynote lectures
Publication date 2002
Start page 1
End page 11
Total pages 11
Publisher Kasetsart University
Place of publication Bangkok, Thailand
Keyword(s) soil water repellency
hydrophobicity
rhizosphere, organic compounds
Summary Although soils are generally considered to wet readily, some are actually water repellent at the surface and in the rhizosphere. This phenomenon occurs at low to moderate moisture contents and has been reported from soils under a range of vegetation types and from many regions around the globe. Water repellency in soils can have serious environmental implications including reduced seed germination and plant growth as well as irrigation efficiency, accelerated soil erosion, and enhanced leaching of agrochemicals through preferential flow. it has been proposed that water repellency is caused by the accumulation of hydrophobic organic compounds released as root exudates, microbial byproducts or from decomposing organic matter, which are deposited on mineral or aggregate surfaces, or are present as interstitial matter, Few studies to date have attempted to isolate and characterize these compounds and their structure is therefore only poorly understood, These studies have generally focussed on only a single soil or a small range of samples, have not included non-repellent soils as a control and have not always been able to demonstrate that the substances isolated are indeed responsible for repellency formation.

This study reports on the first part (extraction procedures) of a research programme addressing these gaps in current knowledge by investigating a wide range of severely repellent and wettable ‘control’ samples from different countries, and by including assessments of extraction efficiency and ability of extracts to cause repellency. Analytical methods include DRIFT (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) of soils and IR (Infrared) analysis of extracts.

Key findings are that (i) soil sample heating after extraction is valuable in assessing the effectiveness of the extraction procedure, (ii) Soxhlet extraction using isopropanol/ ammonia (70/30 v/v) was the most effective method in extracting hydrophobic compounds, while leaving the ability of extracted compounds to induce water repellency virtually unaffected, (iii) wettable control soils also contain hydrophobic substances capable of inducing water repellency, (iv) the amount of organic compounds extracted was poorly related to sample repellency, indicating that compounds responsible for repellency may only represent a small fraction of the extract, (v) differences in extraction efficiency between different samples indicate that the compounds responsible may differ generically and/or in terms of their bonding to minerals, and (vi) the combination of repellency assessments with DRIFT on soils and JR on extracts used with internal standards has considerable potential to allow quantification of CH bearing organic matter in the soil, the efficiency of extraction processes for its removal, and its significance in causing water repellency in soils.
Language eng
Field of Research 050305 Soil Physics
Socio Economic Objective 970105 Expanding Knowledge in the Environmental Sciences
HERDC Research category E2 Full written paper - non-refereed / Abstract reviewed
Copyright notice ©Reproduced with the specific permission of the copyright owner.
Persistent URL http://hdl.handle.net/10536/DRO/DU:30013873

Document type: Conference Paper
Collections: School of Ecology and Environment
Open Access Collection
Connect to link resolver
 
Unless expressly stated otherwise, the copyright for items in DRO is owned by the author, with all rights reserved.

Every reasonable effort has been made to ensure that permission has been obtained for items included in DRO. If you believe that your rights have been infringed by this repository, please contact drosupport@deakin.edu.au.

Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 0 times in TR Web of Science
Scopus Citation Count Cited 0 times in Scopus
Google Scholar Search Google Scholar
Access Statistics: 511 Abstract Views, 284 File Downloads  -  Detailed Statistics
Created: Tue, 21 Oct 2008, 14:15:49 EST

Every reasonable effort has been made to ensure that permission has been obtained for items included in DRO. If you believe that your rights have been infringed by this repository, please contact drosupport@deakin.edu.au.