ESTIMATING THE ATTERBERG LIMITS OF SOUTHERN SASKATCHEWAN SOILS FROM TEXTURE AND CARBON CONTENTS

The soil water contents at the liquid and plastic limits (the Atterberg limits) are widely used in the classification of soils for engineering purposes. Approximately 500 soil samples (129 Ap horizons and 417 B and C horizons) collected over several years as part of the ongoing soil survey program in Saskatchewan were analyzed for texture and Atterberg limits. On about half of the samples water retention (-33 kPa and -1500 kPa matric potential and air dryness), and organic and inorganic C were also determined. The relationship between the Atterberg limits and soil properties was explored through correlation and regression analysis. Clay and organic matter content explained most of the observed variation in the Atterberg limits of the Ap horizons. Clay was the most important independent variable in the B and C horizons, while inorganic C had only a relatively small impact.