Evaluating the potential to impose partial root zone drying (PRD) on clay soils in commercial cotton production systems

McKeering, Loretta M. (2004) Evaluating the potential to impose partial root zone drying (PRD) on clay soils in commercial cotton production systems. [USQ Project] (Unpublished)


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This project investigated the ability to create effective partial root zone deficits for
cotton on cracking clay soils. The project involved parameterising and validating the
model by comparing simulated with measured results obtained from a partial root
zone drying field trial. After validation, the model was used to simulate soil-water
movement associated with the range of different irrigation frequencies and water
volumes that could be applied commercially using low energy precision application
nozzles fitted to centre pivots and lateral move machines.
From the validation, the predictive accuracy of the model simulation was found to
progressively decrease from 69% to 64% and then 39% for increasing simulated
growth periods of 17, 26 and 63 days. The simulated soil moisture content in the
surface layers immediately under the plant row were found to be generally lower
than the measured soil moisture in the field possibly due to difficulties in
appropriately parameterising the root extraction pattern. Similarly, the simulated soil
moisture at profile depths greater than 100 cm were slightly under-predicted
presumably due to parameterisation errors in the soil hydraulic properties for this
layer. Based on the requirement for a soil water gradient of at least 100 kPa, none of
the irrigation strategies simulated on the soil produced a soil moisture potential
gradient large enough to induce partial root zone drying effects without causing
deficit irrigation.
A second investigation collected soil data for use in the model, however the model
would not run using this data. The results of this project suggest that it may be
difficult to implement PRD strategies on cracking clay soils for commercial cotton
production. However further work is required to confirm the simulated soil-water
movement under field conditions and to assess the impact of other local
environmental conditions (eg. rainfall) on the potential to induce PRD responses.

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Item Type: USQ Project
Refereed: No
Item Status: Live Archive
Depositing User: epEditor USQ
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Agricultural, Civil and Environmental Engineering
Date Deposited: 11 Oct 2007 00:13
Last Modified: 02 Jul 2013 22:30
Uncontrolled Keywords: irrigation, partial root zone drying (PRD), soil water movement model, HYDRUS-2D, clay soils, commercial cotton production, Jondaryan
Fields of Research (FoR): 09 Engineering > 0999 Other Engineering > 099901 Agricultural Engineering
07 Agricultural and Veterinary Sciences > 0799 Other Agricultural and Veterinary Sciences > 079901 Agricultural Hydrology (Drainage, Flooding, Irrigation, Quality, etc.)
URI: http://eprints.usq.edu.au/id/eprint/67

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