Uptake of water from a Kandosol subsoil: I. Determination of soil water diffusivity |
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Authors: | David M. Deery John B. Passioura Jason R. Condon Asitha Katupitiya |
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Affiliation: | 1. High Resolution Plant Phenomics Centre, CSIRO Plant Industry, Clunies Ross St Black Mountain, Canberra, ACT 2601, Australia 2. CSIRO Plant Industry, Clunies Ross St Black Mountain, Canberra, ACT 2601, Australia 3. EH Graham Centre for Agricultural Innovation (NSW Department of Primary Industries and Charles Sturt University), School of Agricultural and Wine Sciences, Charles Sturt University, Wagga Wagga, NSW, 2678, Australia
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Abstract: | Aims To determine soil water diffusivity, D(θ), on undisturbed field soil at medium to low water content (suction range from 10 to 150 m of water), for the purpose of modeling the uptake of water by plant roots. Methods The method is based on the analysis of one-step outflow induced by a turbulent stream of dry air over the exposed end of a soil core, with the other end of the core enclosed. The outflow is measured through time as the change in the weight of the core as it sits on a recording balance. D(θ) is calculated by deconvoluting the measured outflow function. Results Over the suction range of 10 to 150 m of water, D(θ) calculated on the undisturbed soil ranged from 20?×?10?9 to 10?×?10?9 [m2?s?1], substantially higher than other published estimates over this range in suction. Conclusions These unusually large values cast doubt on the view that flow of water to roots limits uptake of water from the targeted subsoil. |
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