METHODS FOR THE GRANULOMETRIC ANALYSIS OF SOIL FOR SCIENCE AND PRACTICE

Abstract

The publication contains the descriptions of two analyses of soil texture and the bed beneath (subsoil). For objective reasons, the first method – TA is very labor and time consuming, yet exact and verifiable, of a precisely defined indication error. It is conducted by a complete refractioning of a soil sample which have been dispergated in distilled or demineralized water. The analysis was based on the rule of refractioning the whole sample into clay, silt and sand fractions through floating the soil suspension. The sum of indicated fractions was at least 98% in percentage by weight which means that the analysis error did not exceed 2%; for the most of the analyses it still did not even exceed 1%. The method of whole sample refractioning, TA method for short, is one of the basic, classic method of soil texture analysis. The main aim of this method is the verification of shortened, partial or simplified methods such as pipette, areometric and laser methods, etc. TA method can be used in scientific research when exactness and reliability of texture analysis is especially important. The second method of the granulometric analysis, ALP method for short, is based on pipette methods. Samples of soil suspension of 1000 ml are taken with a pipette of about 38.5 ml capacity, yet the pipetting capacity is determined by weight with 0.001 ml exactness. The pipette is constructed of four pipe probes of 1 cm diameter and placed at the depth of 9.5 cm the suspension is collected from the sphere of 9.5–10 cm. Sand fractions which were nor indicated with a pipette method (> 0.05 mm) were analyzed with TA method by floating the particles < 0.05 mm with a suction device. Pipette analysis error was between -3% and +3%. For most of the results, the error did not exceed 2%. Errors were divided proportionally onto each fraction. A pipette method may be used in scientific research but first of all – in those conducted for practical needs.