Modelling of water and solutes in permanent raised beds

Cook, F. J. and Knight, J. H. and Humphreys, E. and McHugh, A. D. and Tisdall, J. and Hamilton, G. and Roth, C. H. (2009) Modelling of water and solutes in permanent raised beds. In: 18th World IMACS Congress and International Congress on Modelling and Simulation (MODSIM09): Interfacing Modelling and Simulation with Mathematical and Computational Sciences, 13-17 Jul 2009, Cairns, Australia.

Abstract

Permanent raised beds (PRB) are an agricultural cultural method that can improve crop productivity and health of soils. Australian Centre for International Agricultural Research (ACIAR) has funded a number of projects in developing countries but was concerned that the short-term benefits may be at the cost of longterm losses due to solute pollution of groundwater or salinisation of the beds. A modelling study was undertaken to consider the water and solute flow in raised beds in relation to the soil physical properties to improve understanding of the PRB system. HYDRUS(1D, 2D/3D) was used as the modelling platform. The domain used for the simulations is shown in figure 1. The results show that a simple model for infiltration into the raised beds is useful for estimating the width of the raised bed for most soils especially if the sorptivity was measured on a trial bed. Compaction of the furrow between the beds commonly occurs due to vehicle traffic. Compaction under the furrow was simulated and this showed that water penetration horizontally was slowed as cumulative infiltration with time was reduced. However, for the same amount of cumulative infiltration the penetration horizontally was greater than when no compaction occurred. Drainage of the beds when an impermeable layer occurs in the soil shows that a simple inversion of the moisture characteristic relationship could be used to estimate the water potential profile in the bed. This also shows that for clay soils the beds must be excessively high for them to drain effectively through seepage to the furrow. The leaching of fertilizers by furrow irrigation was investigated to determine at what distance from the furrow fertilisers should be placed to reduce leaching during irrigation. This distance was shown to be soil dependent. Salinisation due to evaporation from a shallow water table is likely to occur if a saline watertable occurs at < 0.5 m in sand and < 1.5 m in loam and clay soils unless properly managed. (Graph Presented).


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Item Type: Conference or Workshop Item (Commonwealth Reporting Category E) (Paper)
Refereed: Yes
Item Status: Live Archive
Additional Information: Copyright © 2009. The Modelling and Simulation Society of Australia and New Zealand Inc. and the International Association for Mathematics and Computers in Simulation. This publication is copyright. It may be reproduced in whole or in part for the purposes of study, research, or review, but is subject to the inclusion of an acknowledgment of the source.
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Agricultural, Civil and Environmental Engineering
Date Deposited: 31 Oct 2014 02:29
Last Modified: 31 Oct 2014 02:46
Uncontrolled Keywords: infiltration; irrigation; moisture content; permanent raised beds; solute transport
Fields of Research : 09 Engineering > 0907 Environmental Engineering > 090702 Environmental Engineering Modelling
07 Agricultural and Veterinary Sciences > 0701 Agriculture, Land and Farm Management > 070104 Agricultural Spatial Analysis and Modelling
07 Agricultural and Veterinary Sciences > 0701 Agriculture, Land and Farm Management > 070107 Farming Systems Research
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970107 Expanding Knowledge in the Agricultural and Veterinary Sciences
URI: http://eprints.usq.edu.au/id/eprint/26295

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