Effect of water quality on soil structure and infiltration under furrow irrigation

Emdad, Mohammad R. and Raine, Steven R. and Smith, Rod J. and Fardad, Hossein (2004) Effect of water quality on soil structure and infiltration under furrow irrigation. Irrigation Science, 23 (2). pp. 55-60. ISSN 0342-7188

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Abstract

The quality of irrigation water has the potential to significantly affect soil structural properties, infiltration and irrigation application efficiency. While the effect of electrolyte concentration (as indicated by the electrical conductivity EC) and sodium adsorption ratio (SAR) have been studied under laboratory conditions, the effect on soil profile structural properties and irrigation performance have not been widely investigated under field conditions. In this paper, water with three different levels of sodium (SAR = 0.9, 10 and 30) was applied as alternative treatments to a clay loam soil. The application of 238–261 mm of medium- to high-SAR water was found to reduce aggregate stability, increase the bulk density of both the surface crust and underlying soil, and reduce the total depth of infiltration and final infiltration rate. Where low-SAR water was used, there was no significant (P<0.05) difference in final infiltration rate after the first four irrigations. However, where moderate- and high-SAR water was applied after the first four irrigations with the low EC-SAR water, the final infiltration rate was found to decrease on each of the successive irrigation events. For the moderate- and high-SAR treatments, this suggests that a steady-state equilibrium had not been reached within that part of the soil profile impeding infiltration. It is proposed that the initial reduction in infiltration is related to the physical processes of slaking leading to the development of an apedal, hardsetting surface soil layer. Similarly, it is proposed that the subsequent increase in bulk density and decline in infiltration where moderate and high EC-SAR water is applied is due to an increase in clay tactoid swelling reducing the size of the conducting micropores, dispersion blocking pores, and/or an increase in the thickness of the apedal surface layer. The reduction in infiltration associated with the use of high-SAR irrigation water was found to reduce the performance of the irrigations, with the application efficiency of the final irrigation decreasing from 40% where the low-SAR water was used, to 21% where the high-SAR water was applied. The implications for surface irrigating with water containing high sodium levels are discussed.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Deposited in accordance with the copyright policy of the publisher.
Depositing User: Assoc Prof Steven Raine
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Agricultural, Civil and Environmental Engineering
Date Deposited: 11 Oct 2007 00:39
Last Modified: 02 Jul 2013 22:37
Uncontrolled Keywords: soil profiles; sodium adsorption ratio; SAR
Fields of Research (FOR2008): 09 Engineering > 0905 Civil Engineering > 090508 Water Quality Engineering
05 Environmental Sciences > 0503 Soil Sciences > 050305 Soil Physics
07 Agricultural and Veterinary Sciences > 0799 Other Agricultural and Veterinary Sciences > 079901 Agricultural Hydrology (Drainage, Flooding, Irrigation, Quality, etc.)
Socio-Economic Objective (SEO2008): E Expanding Knowledge > 97 Expanding Knowledge > 970107 Expanding Knowledge in the Agricultural and Veterinary Sciences
Identification Number or DOI: doi: 10.1007/s00271-004-0093-y
URI: http://eprints.usq.edu.au/id/eprint/1308

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