Premium
Rapid Method for Assessment of Soil Structural Stability by Turbidimeter
Author(s) -
Zhu Yingcan,
Marchuk Alla,
McLean Bennett John
Publication year - 2016
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2016.07.0222
Subject(s) - turbidity , dilution , dispersion (optics) , turbidimetry , particle size , soil water , soil science , environmental science , soil test , particle (ecology) , soil texture , materials science , chemistry , geology , chromatography , physics , optics , thermodynamics , oceanography
Core Ideas A quantitative dispersion assessment chart is developed for rapid diagnosis of soil structural stability. Turbidity and the amount of dispersed clay have a strong linear relationship. The color and mean particle size of colloidal solution has a negligible effect on the linearity of turbidity. A rapid and inexpensive method to evaluate soil structural stability via assessment of soil clay dispersion is needed. Such a method would provide critical information for decision‐making for soil and agricultural management not currently undertaken due to the expense of testing. The aim of this work was to validate the use of a turbidimeter for quantifying clay released from soil and to relate this back to dispersive parameters. Ten Australian soils with different physicochemical properties were studied. Six‐step dilution was used to adjust the clay suspensions sequentially by dilution from a datum concentration of 4000 nephelometric turbidity units (NTU). The linearity of turbidity by dilution was verified, considering the effects of soil color and mean particle size. There was a strong correlation between turbidity (NTU) and dispersed clay (mg L −1 , % of soil) for each soil. Clay particle size was related to turbidity response, although the coefficients between turbidity and dispersed clay were very close irrespective of mean particle size differences. Dispersed clay was concluded to be accurately quantified using a turbidimeter after spontaneous and mechanical dispersion. A semi‐quantitative dispersion assessment chart was developed for rapid assessment of soil structural stability, the application of which is intended to provide rapid diagnosis and to act as an important index for soil management practitioners. Additionally, when dispersed clay was combined with electrical conductivity and clay content parameters, the dispersive indices (cation ratio of soil structural stability and exchangeable dispersive percentage) were reasonably predicted at a resolution useful for farm management decisions.