Methods of mechanical dispersion for determining granulometric fractions in soils using four dispersant solutions

Abstract

Sieve analysis studies depend on obtaining suspensions of fully-dispersed and stable samples to facilitate the quantification of the fractions of soil aggregates. The aim of this study was to compare the percentage of fractions obtained with four chemical dispersants and two methods of mechanical dispersion. To carry out this investigation, nine soils were selected from the departments of Cordoba and Sucre and four methodologies using chemical dispersions: ((NaPO3)6 + Na2CO3), (NaOH) 1M, (Na4P2O7) 0.1M pH 10, and CH3COONa 1M, and two methodologies of mechanical dispersion were evaluated: a slow one at 60 rpm for 6 hours and another at 4,000 rpm for 15 minutes. The results were analyzed using a correlation test and contrasts. It was verified that the highest content of clay in the soil samples was found when using the 60 rpm agitation methodology, due to greater dispersion of the granulometric fractions. Likewise, when comparing the different methods of chemical dispersion, it was determined that NaOH had the highest dispersing ability and sodium acetate presented a low efficiency in the separation of soil particles.