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Growth, water use efficiency, and adaptive features of the tree legume tagasaste (Chamaecytisus proliferus Link.) on deep sands in south-western Australia

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Lefroy, EC and Pate, JS and Stirzaker, RJ (2001) Growth, water use efficiency, and adaptive features of the tree legume tagasaste (Chamaecytisus proliferus Link.) on deep sands in south-western Australia. Australian Journal of Agricultural Research, 52 (2). pp. 235-246. ISSN 0004-9409

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Abstract

Components of the water balance of an alley cropping system were measured to assess the extent to which tree rows 30 m apart with access to a fresh, perched watertable at 5 m depth were able to capture deep drainage from an inter-cropped cereal–legume rotation. Neutron probe data showed that the 4-year-old trees, cut back to 0.6-m high at the beginning of the experiment, depleted soil water to 2, 4, and 8 m laterally from the tree rows in their first, second, and third years of coppice regrowth, respectively. Combining data from soil water depletion in summer and comparisons of deuterium: hydrogen ratios of groundwater, xylem sap of trees, and herbaceous plants, it was shown that tagasaste trees drew on soil water for 80% of their transpiration in the first winter and 40% in the second, while switching to near total dependence on groundwater each summer and early autumn. Tree water use on a whole plot basis was 170 mm in 1997 (68% from groundwater) v. 167 mm in 1998 (73% from groundwater). Recharge to the perched watertable was estimated to be 193 mm under sole crop in 1998 (52% of rainfall), reducing to 32 mm when uptake of groundwater by trees was included. The degree of complementarity between tagasaste trees and crops in alley cropping used for water management is quantified for 1998 by calculating the ratio of the distance over which trees reduced drainage to zero to the distance over which they reduced crop yield to zero. It is concluded that segregated monocultures of trees and crops would be a more appropriate strategy than a closely integrated system such as alley cropping in this case.

Item Type: Article
Keywords: agroforestry, stable isotope natural abundance, time domain reflectometry
Journal or Publication Title: Australian Journal of Agricultural Research
Page Range: pp. 235-246
ISSN: 0004-9409
Identification Number - DOI: 10.1071/AR00035
Date Deposited: 18 Jan 2008 03:15
Last Modified: 18 Nov 2014 03:26
URI: http://eprints.utas.edu.au/id/eprint/2717
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