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Soil color determination and its use on the estimative of hematite contents.

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Author(s):
Rogério Costa Campos
Total Authors: 1
Document type: Master's Dissertation
Press: Piracicaba. , gráficos, ilustrações, tabelas.
Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
Defense date:
Examining board members:
Jose Alexandre Melo Dematte; Ricardo Marques Coelho; Celia Regina Montes
Advisor: Jose Alexandre Melo Dematte
Field of knowledge: Agronomical Sciences - Agronomy
Indexed in: Banco de Dados Bibliográficos da USP-DEDALUS; Biblioteca Digital de Teses e Dissertações - USP
Location: Universidade de São Paulo. Biblioteca Central da Escola Superior de Agricultura Luiz de Queiroz ; ESALQ-BC/t631.43; C198d; 78879
Abstract

The objectives of the present work were: (a) Determine and evaluate color by the conventional method, and its comparison with colormeter equipment and their implication with soil classification; (b) Estimate of hematite contents by using soil color data. The hue of 80 samples of soils was determined by five experienced soil scientists by the comparison with the Munsell’s soil color charts and by a colorimeter. Color of 15 soil samples from different sites of São Paulo State were determined by colorimeter and from reflectance data obtained with radiometer. The correlation coefficients, varying from 0,68 to 0,94 of hue determinations, showed that the soil scientists produced data that validated the study. However, there was confirmation that the measures accomplished by soil scientists were not coincident and also differed from the colormeter. The values of precision index (PI) indicated an agreement of only 8,75% in moist samples and 17,5% in the dry samples, which would result in mistakes in the soil classification. Colors were achieved by L*a*b* and Munsell systems. For each sample, hematite content were determinated and the redness indexes (RI) calculated. The RI presented high correlation with hematite contents, and higher correlations for colors obtained in L*a*b* than those obtained in Munsell system. Exponential models were more effective in predicting hematite contents. (AU)