Magnetic and spectral signatures of Cerrado soils in the state of Goiás, Brazil

Abstract

-The objective of this work was to estimate the iron oxide contents (hematite and goethite) and to characterize the color and the spectral and magnetic signatures of Cerrado soils in the state of Goiás, Brazil. Six Oxisols and one Inceptisol were studied. Spectral and magnetic signatures were determined by diffuse reflectance spectroscopy (DRS) and magnetic susceptibility, respectively. Then, the spectral curves and the second derivative calculations were used to determine hematite and goethite contents, as well as soil color after conversion into tristimulus values. Hematite and goethite contents were also obtained by x-ray diffractometry, and soil color was also defined in the field (Munsell color chart). The values for the isomorphic substitution of iron by aluminum and the degree of redness were also determined. DRS can be used to estimate hematite and goethite contents, as well as the color of Cerrado soils in the state of Goiás. The spectral signature can point out the main soil properties related to the contents of organic matter, iron oxides, kaolinite, and gibbsite. The magnetic signature, characteristic of soils rich in iron oxides (hematite and goethite), shows the predominance of pedogenic minerals.

Soil mineralogical attributes estimated by color as accessed by proximal sensors and machine learning

“…Previous studies have already proven the efficiency of using DRS to estimate the Hm and Gt contents (Bahia et al, 2015; Fernandes et al., 2017; Ramos et al., 2020; Silva et al., 2020; Viscarra Rossel et al., 2010). Moreover, other studies have shown the use of the RGB system to predict Fe contents (Heil et al., 2020; Levin et al., 2005; Viscarra‐Rossel & Mcbratney, 2008), which are considered as indicators of the Fe oxide contents in the soil (Kampf et al., 2015).…”

“…The advancement of technology has allowed the use of diffuse reflectance spectroscopy (DRS) to characterize soil color (Aquino et al., 2016; Fernandes et al., 2017; Ramos et al., 2020; Silva et al., 2020; Viscarra Rossel et al., 2010). This method allows for qualitative and quantitative acquisition through the reflectance of the energy applied to the sample (Torrent & Barrón, 2008).…”

“…This method allows for qualitative and quantitative acquisition through the reflectance of the energy applied to the sample (Torrent & Barrón, 2008). Data analysis through software and professionals trained in the interpretation of results allows the use of this tool for agricultural planning and definition of management zones (Marques et al., 2014), soil genesis (Dantas, Marques, et al., 2014), erosion potential (Dantas, Martins Filho, et al., 2014), phosphorus adsorption potential (Camargo et al., 2015; Peluco et al., 2015), mineralogical characterization (Bahia et al, 2015; Fernandes et al., 2017; Viscarra‐Rossel, 2011), and organic matter content (Demattê et al., 2011).…”

Spatialization of chemical attributes, penetration resistance and magnetic susceptibility of the soil in a Cerrado area

“…The Brazilian Cerrado has become one of the main areas of agricultural production in the country in recent years, and the opening and cultivation in this region, mainly in the central part of the country and recently in the Northeast of Brazil, have contributed to a substantial increase in national food production, but the intensification of soil tillage in conventional planting systems causes changes in physical, chemical and biological properties of the soil (Fernandes et al, 2017;Matias et al, 2019).…”

Atributos químicos, físicos e suscetibilidade magnética e sua probabilidade de ocorrência em solo do cerrado piauiense em área de pastagem nativa

“…para o desenvolvimento e crescimento do sistema radícula em decorrência do maior grau de compactação. SegundoTardieu (1994), a RSP está diretamente relacionada com a textural e condições estruturais do solo, como também o tipo e o teor do mineral argila presente(Fernandes et al (2017) encontraram resultados parecidos com desta pesquisa.Os valores da mediana da maioria dos atributos físicos e químicos da área estudada estão próximos da média, evidenciando que estes apresentam ou se aproximam da distribuição normal. A distribuição normal dos dados esperada na estatística descritiva não é um parâmetro de exigência na geoestatística(LUNDGREN et al, 2017).Ainda na Tabela 1 nota-se que apenas o Al 3+ e a areia apresentaram valores assimétrico a esquerda, já os valores de coeficientes de curtose (Ck) dos atributos pH, MO, P, K, H+AL, CTC e RSP apresentaram-se fora dos limites considerados como aceitáveis (-2 < Ck < +2), de conformidade(DE NEGREIROS NETO et al, 2014CARNEIRO et al, 2016).As correlações são apresentadas na tabela 2.…”