AIR CONTENTS IN SOILS ABOVE A HIGH WATER TABLE — APPLICATION TO DRAINAGE CLASSIFICATION OF SOILS
Studies were conducted at 10 sites with a high water table with a view to classifying soil drainage status from a knowledge of water table depth and water retention properties of the soil. The parameter used to assess soil drainage status was air-filled porosity. The average error in predicting air-filled porosity in the field from water retention data was 2.3%. It was found that air-filled porosity in the water retention samples could be predicted from soil components to within 3.4–5.9% of the actual value (on the average). This suggests that where water retention data are not available, a knowledge of soil components and water table depth may be sufficient to obtain an estimate of air-filled porosity. A system of soil drainage classification based on air-filled porosity is proposed.