Abstract

Several methods have been developed in the past to estimate the mechanical components of soil and each one has its own merits and demerits. Among them, International Pipette Method is considered to be accurate and is widely used. The Bouyoucos (1927) Hydrometer method, though not involving gravimetric estimations, takes considerable time and requires specialised apparatus. When a large number of soils have to be examined in a short time as in Soil Testing Laboratorics or in Soil Survey Work, Feel Method" is employed which depends upon the skill and vast experience of the individual and differs to a great extent between different evaluations. Durairaj (1961) while studying the mechanical components of South Indian soils brought out clearly that the proportions of clay, and fine and coarse sand in soils are highly correlated among themselves. He showed that the correlation was dependent upon soil type, so that for a given soil type and a given value of one of the mechanical components, only ore pattern of the values of the rest was possible. He also devised an apparatus for the rapid method of mechanical analysis for the purpose of field workers. Based on his study, his rapid method of mechanical analysis was modified to suit laboratory conditions. This method involves the estimation of course and fine sand fractions, the other fractions being calculated using the multiple regression equations derived for each soil type. Details regarding at comparative study between the values by modified Durairaj method and by International Pipette Method are reported in this paper.

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