Evaluating Soil Water Matric Pressure and Sorptivity Relationship as Affected by some Properties of a Clay Soil
Sorptivity (S) is the fundamental variable controlling the early infiltration process. Besides soil properties, soil initial water content (θi) and/or matric pressure (hi) are key factors determining extent of S. Assessment of interrelationship among S, hi and soil properties can provide a considerable insight into understanding the behaviour of dry soils to rainfall or irrigation water. This study was conducted to evaluate relationship between S and some selected soil parametric and morphometric properties within a range of hi. Sixteen undisturbed soil samples (5 cm id, 5 cm length) were taken from the topsoil (0-15 cm) of a paddy soil with clay texture. Sorptivity was measured with a mini-disc infiltrometer (MDI) on the samples equilibrated at h, ranging from -20 to -1500 kPa. A parameter (η), representing the relationship between S and hi, was introduced. Correlation analysis was conducted between η and selected soil morphometric and parametric properties. Soil structure and clay content appeared the most important soil attributes influencing S-hi relation between -200 and -1500 kPa. The results provided a fundamental understanding on S-hi-soil properties interrelations in a clay soil. The methodology developed in this study can be used to evaluate S-hi relationship across different soils and scales.