Title:	Reflectometria no domínio do tempo (TDR) para determinação do conteúdo de água em solos tropicais do Distrito Federal
Other Titles:	Time domain reflectometry (TDR) for Brazilian Federal District tropical soils in the water content determination
Authors:	Costa, Bruna Freire Domingues da
Orientador(es)::	Leão, Tairone Paiva
Assunto::	Água - uso Recursos hídricos - monitorização ambiental Racionalização de água
Issue Date:	26-Sep-2017
Data de defesa::	24-Feb-2017
Citation:	COSTA, Bruna Freire Domingues da. Reflectometria no domínio do tempo (TDR) para determinação do conteúdo de água em solos tropicais do Distrito Federal. 2017. xiii, 64 f., il. Dissertação (Mestrado em Agronomia)—Universidade de Brasília, Brasília, 2017.
Abstract:	Brazil is a privileged country regarding water resources. However, these are heterogeneously distributed, since most of the water is located in lower population density areas. Since agriculture is a major user of water, the proper management and efficient use of this resource is dependent of the water rationalization and resources sustainability. Monitoring soil water content is crucial for farming practices, particularly for measuring its variation and optimizing irrigation management. The TDR technique is an important method to determine soil water content, which is the property that have more effect on the dielectric permittivity of the soil (this constant can also be influenced by the soil mineralogy). The aim of this study was to establish calibration equations between soil water content and dielectric permittivity for Aeric Endoaquent, Typic Ustorthent, Typic Haplosaprist, Anionic Acrustox, Rhodic Haplustox and to compare them with the universal model proposed in the literature (Topp et al.,1980), using the standard thermogravimetric model of soil water content measurement as a reference. The possible interference and effects of iron and aluminum oxides in the TDR calibration with determination of magnetic permeability was also investigated. For each soil class and for the whole experimental set, cubic polynomial, logarithmic and square root models were adjusted between soil water content (dependent variable) and dielectric permittivity (independent variable). The precision and the accuracy of the models were assessed using the coefficient of determination (R2), the Root Mean Squared Error (RMSE) and the 1:1 line. The model proposed by Topp et al. was the least adequate to estimate the water content of the soil classes studied. Rhodic Haplustox and Aeric Endoaquent data were better adjusted by the logarithmic model equation, with low RMSE and high R2. The Anionic Acrustox, the Typic Ustorthent, the Typic Haplosaprist and the set of all the soils were better represented by the cubic polynomial model, which makes it the best adjusted model for these soils. Considering only the mineral soils, that is, excluding the Typic Haplosaprist from the models, an overall best fit equation is obtained, in the form of a cubic polynomial. The values of magnetic permeability found in the soils were low, as no ferrimagnetic mineral was detected by X-ray diffraction. Thus, the presence of oxides, mainly hematite and goethite, according to the magnetic permeability were not significant in these models to adjust water content in the studied soils.
metadata.dc.description.unidade:	Faculdade de Agronomia e Medicina Veterinária (FAV)
Description:	Dissertação (mestrado)—Universidade de Brasília, Programa de Pós-Graduação em Agronomia, Faculdade de Agronomia e Medicina Veterinária, 2017.
metadata.dc.description.ppg:	Programa de Pós-Graduação em Agronomia
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Appears in Collections:	Teses, dissertações e produtos pós-doutorado

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