University of Tehran Press Iranian Journal of Soil and Water Research 2008-479X 51 3 2020 05 21 Comparison of Three Commonly Used Concepts in Explaining Soil Water Availability for Plants (CPAW, EI and Mh0) and Their Feasibility as an Indicator of Soil Management Comparison of Three Commonly Used Concepts in Explaining Soil Water Availability for Plants (CPAW, EI and Mh0) and Their Feasibility as an Indicator of Soil Management 687 696 74255 10.22059/ijswr.2019.283647.668236 FA Ehsan Ghezelbash Ph.D student, , Department of Soil Science and Engineering, Faculty of Agricultural Engineering and Technology, University of Tehran, Iran 0000-0002-0386-2437 Mohammad Hossein Mohammadi Associate Professor, Department of Soil Science and Engineering, Faculty of Agricultural Engineering and Technology, University of Tehran, Iran 0000-0003-0596-7539 Journal Article 2019 06 30 The complexity of the concept of soil water availability has led to the emergence of a variety of methods to estimate it, which have always been changing, refining, and replacing. Among those, the conventional method of plant available water (CPAW=FC-PWP) due to convenient measurement has received more attention. In theory, however, the methods of Integral Energy (E_I) and Kirchhoff Potential (M_h0) have been considered due to the interference of soil properties and plant ability for water uptake. In this  study, the available water was calculated with CPAW, E­_I and M_h0 concepts in a wide range of soils (72 samples) with various physical properties and results were compared. Also, different upper limits were tested to determine the water availability and the new field capacity moisture coefficient was used as the upper limit of the concept of water availability. Despite the weak correlation between E_I and M_h0, the trend of their variations in different soils is somewhat similar, indicating their similarity in the estimation of available water for plants. In contrast, the lack of a clear relationship between E_I and M_h0 with CPAW confirmed their lack of correlation in explaining water availability of the plant. The convenience of using CPAW makes it even more preferable to study the variability of soils in terms of hydraulic properties. On the other hand, the use of E_I and M_h0results will be useful for explaining the available water content but still needs to be modified in terms of determining threshold limits. The complexity of the concept of soil water availability has led to the emergence of a variety of methods to estimate it, which have always been changing, refining, and replacing. Among those, the conventional method of plant available water (CPAW=FC-PWP) due to convenient measurement has received more attention. In theory, however, the methods of Integral Energy (E_I) and Kirchhoff Potential (M_h0) have been considered due to the interference of soil properties and plant ability for water uptake. In this  study, the available water was calculated with CPAW, E­_I and M_h0 concepts in a wide range of soils (72 samples) with various physical properties and results were compared. Also, different upper limits were tested to determine the water availability and the new field capacity moisture coefficient was used as the upper limit of the concept of water availability. Despite the weak correlation between E_I and M_h0, the trend of their variations in different soils is somewhat similar, indicating their similarity in the estimation of available water for plants. In contrast, the lack of a clear relationship between E_I and M_h0 with CPAW confirmed their lack of correlation in explaining water availability of the plant. The convenience of using CPAW makes it even more preferable to study the variability of soils in terms of hydraulic properties. On the other hand, the use of E_I and M_h0results will be useful for explaining the available water content but still needs to be modified in terms of determining threshold limits. https://ijswr.ut.ac.ir/article_74255_c6471f8cd785f2d573efd44fe29f96d7.pdf