Analysis of the Soil Sand Fraction and Recent Sediments Deposits: An Approach Based on Two-Dimensional Image Analysis. Issue 11 (November 2016) - Bovi, Renata Cristina
Abstract : Abstract: In this study, we propose a methodology (ImaGrain) for quantifying the sand fractions from two-dimensional images obtained from thin sections of undisturbed soil samples. Samples for this analysis were collected from soil horizons and sediment layers of two profiles and two pits, located in the Experimental Station of Tupi, Piracicaba, São Paulo, Brazil. Data from image analysis were used to calculate the mean, median, S.D. (a measure of sorting), skewness, and kurtosis of the size distribution of sand grains, and the results were compared with those obtained with the sieving (standard) method. Roundness of the sand grains was quantified with the ImaGrain method. The results showed that both methods classify the mean grain size as fine sand and that the values of S.D., skewness, and kurtosis for all samples were also similar. The sand grains of the sediment layers and soil horizons had similar degrees of sand grain roundness with a dominance of rounded and moderately rounded sand grains. Based on our results, ImaGrain should be explored further as a tool to quantify the soil sand fraction and for determining transport and deposition patterns. Image analysis also allows classifying the sand grain roundness, an important parameter that is not determined by the standard method.