Studies on the moisture retention characteristics of alluvial soils of Kerala

Abstract

An experiment was conducted in the College of Horticulture, Vellanikkara during the period from September 1982 to July 1983 to study the moisture retention characteristics of alluvial soils of Kerala. Soil samples representing five series located at different districts were collected from fifteen profiles at five depths. Moisture contents were determined at six applied pressures, viz., 0.3, 1, 3,5,10 and 15 bars. The moisture retention was correlated with the organic carbon content and texture of the soil by simple and multiple regression analysis. The study revealed that 50 per cent of the available moisture was depleted at a tension just above one bar, and at 3 bar more than 70 per cent of the available water was extracted. The ranges in the field capacity and permanent wilting point were found to be 21.4 to 32.2 and 12.1 to 16.9 respectively, and the overall mean values 25.8 and 13.9. The correlation study showed that the fine fractions (clay and silt) have significant positive correlation with moisture retention. Both coarse and fine sand fractions gave significant negative correlation. The relationship of organic carbon content with moisture retention and available water was positive, but not significant even at five per cent level. Prediction equations were developed to determine the available moisture content from known value of textural components and organic carbon content. The coefficients of determination obtained were high indicating that the difference in the quality of soil organic matter and fine fractions in the alluvial soils are not substantial.