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Soil water characteristics are required to describe the availability of soil water to plants and to model the movement of water and solutes in unsaturated soils. They constitute an input for hydraulic conductivity models (Marshall 1958 Millington and Quirk 1959 Brooks and Corey 1964) and are essential for calculating soil water diffusivity from water content data (Nielsen et al. 1964). Measuring soil water characteristics is time consuming and consequently several efforts have been made to predict water retention data from easily and routinely obtainable soil properties. Soil water con tents at various matric potentials have been successfully related to particle size distribution and organic matter contents (Jamison and Kroth 1958 DeJong 1967 Shaykewich and Zwarich 1968 Oosterveld and Chang 1980). Gupta and Larson (1979) used percent sand, silt, clay, and organic matter and bulk density to esti mate the volumetric water content at given tensions. Rogowski (1971) proposed a procedure to estimate the entire soil water characteristic from measured water con tents at air entry and at a tension of 1500 kPa. Unfortunately, the analytical data that are required for the above-described models are not frequently available. For example, in most Canadian soil survey re ports, only one soil profile per soil series is analyzed in sufficient detail to reveal the required input data for these models.
assessment of empirical parameters that describe soil water characteristics
De Jong, R. 1982. ASSESSMENT OF EMPIRICAL PARAMETERS THAT DESCRIBE SOIL WATER CHARACTERISTICS. Canadian Agricultural Engineering 24(2):65-70.
65 - 70