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Revisiting the wet and dry ends of soil integral water capacity using soil and plant properties
Integral water capacity (IWC) approach takes into account various soil physical limitations for calculating plant available water. However, IWC approach cannot distinguish the differences between various plants in water uptake. Therefore, the objectives of this study were i) to modify the approach for including the physiological properties or needs to redefine the wet and dry ends of the IWC and ii) to evaluate the performance of the modified proposed IWC approach (IWCM) by using the experimental data. The restrictions imposed by aeration porosity and rapid drainage flux were calculated using both soil and plant properties to modify the wet end of the IWC. The soil hydraulic and mechanical resistances was ere considered to redefine the dry end in the proposed IWCM. By these approaches, physically meaningful weighting functions were developed for three proposed limiting factors at both ends of wet and dry ranges of soil. Experimental data were obtained from a greenhouse trial with wheat and canola plants in two soil textures (sandy loam and clay loam) for two years. The proposed IWCM were obtained 0.202 and 0.205 m3 m-3 for wheat and 0.189 and 0.194 m3 m-3 for canola in sandy loam and clay loam soils, respectively. These differences of proposed IWCM between wheat and canola in the same soils demonstrate the importance of plant properties on estimation the plant actual available water as IWC. For the root systems with wider range of properties, these differences would be even more appreciable.
SR17025 Accepted 30 October 2017
© CSIRO 2017