pXRF in tropical soils: Methodology, applications, achievements and challenges

Silva, Sérgio Henrique Godinho; Ribeiro, Bruno Teixeira; Guerra, Marcelo Braga Bueno; Carvalho, Hudson Wallace Pereira de; Lopes, Gertrudes Teixeira; Carvalho, Geila Santos; Guilherme, Luiz Roberto Guimarães; Resende, M. D. V. de; Mancini, Marcelo; Curi, Nilton; Rafael, Rogério Borguete Alves; Cardelli, Valeria; Cocco, Stefania; Corti, Giacomo; Chakraborty, Somsubhra; Li, Bin; Weindorf, David C.

doi:10.1016/bs.agron.2020.12.001

Cited by 59 publications

(23 citation statements)

References 109 publications

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“…To know about this subject, we must consider articles that refer to pXRF use in soils with a high content of organic matter. This effect in soils has been recently reviewed by Silva et al [51] when evaluating the application of pXRF in tropical soils. There is common agreement that soil organic matter may cause a scattering and attenuation of signals when a soil sample is irradiated by X-rays and that the influence and interference magnitude of soil organic matter are still poorly understood.…”

Section: Organic Matter Effectmentioning

confidence: 96%

Portable X-ray Fluorescence Analysis of Organic Amendments: A Review

López-Núñez

2022

Applied Sciences

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Portable XRF spectrometry (pXRF) has recently undergone significant technological improvements and is being applied in a wide range of studies. Despite pXRF advantages, this technique has rarely been used to characterize organic amendments and residues. This article reviews those studies undertaken to date in which pXRF is used to characterize these products. Published studies show that pXRF correctly measures elements such as Fe, Pb, Zn, Mn, Ca, and K but gives conflicting results for elements such as Cr, Ni, and As. Among the reasons that may cause the low performance of the technique with certain elements or under certain measurement conditions would be the inadequacy of the analytical comparison procedures used (i.e., digestion with aqua regia), the lack of knowledge of the interfering effects of organic matter, and sample moisture on the XRF signals and the need for a standardized protocol for performing the measurements. However, the speed and low cost of the procedure forecast a greater future use of this technique, especially in cooperation with other fast spectroscopic techniques based on near-infrared (NIRS) or mid-infrared (MIR) spectroscopies. Chemometric procedures based on one or more of these techniques will allow the prediction of elements below the detection limit of pXRF instruments (Cd, Hg), or other properties of organic amendments (organic matter, N, electrical conductivity, cation exchange capacity).

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Section: Organic Matter Effectmentioning

confidence: 96%

Portable X-ray Fluorescence Analysis of Organic Amendments: A Review

López-Núñez

2022

Applied Sciences

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“…The pXRF analyses of ADFE samples were conducted on a DP-600 (Olympus Waltham, MA) spectrometer, during 60 seconds, operating in Soil Mode (Silva et al, 2021;Chakraborty, 2016). To ensure the efficiency of this proximal sensor, two soil materials certified by the National Institute of Standards and Technology (NIST), 2710a, and 2711a, and a material provided by the pXRF manufacturer (check sample) were analyzed by pXRF and the obtained contents were compared with the certified values.…”

Section: Analyses Via Pxrf Spectrometrymentioning

confidence: 99%

“…The pXRF provides the total elemental content of samples and has been successfully employed in many soil studies (Silva et al, 2021;Bakr;Zhu, 2014). It has been adopted for the study of several soil properties, such as texture Zhang, 2011), soil nutritional analysis (Lima et al, 2019;Pelegrino et al, 2021), soil biology (Teixeira et al, 2021), soil mapping (Mancini et al, 2019;Silva et al, 2016), soil genesis and classification (Gozukara;Hartemink, 2021;Silva et al, 2018Silva et al, , 2021Stockmann et al, 2016;Sun et al, 2020), characterization of different land uses (Chakraborty et al, 2019), soil salinity (Swanhart et al, 2014), soil contamination (Horta et al, 2021;Kebonye, 2021), among others, showing up as a useful tool for such studies.…”

Section: Introductionmentioning

confidence: 99%

“…The hypothesis is that the chemical characterization provided by pXRF and its association with geomorphology will improve our knowledge about tropical soils formation. Although in tropical conditions the use of pXRF has increased, without generation of chemical waste ("green analyses") (Silva et al, 2021), this approach was not yet applied to investigate and characterize Oxisols that occur in steep relief. The lowcost and agile methods enabled by pXRF could allow for quick and effective analyses, providing important insights regarding the formation of such soils.…”

Section: Introductionmentioning

confidence: 99%

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Study of an abnormal occurrence of Oxisols in strongly undulated relief in the south of Minas Gerais, Brazil, with support of pXRF and geomorphology

et al. 2021

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Oxisols are the main soils in Brazil and they classically occur in stable and gentle geomorphic surfaces. However, in the south of Minas Gerais State, Oxisols have been observed under strongly undulated relief, a very rare condition for these soils in this physiographic region. Therefore, this work aimed to assess the elemental dynamics and relief enhanced with portable X-ray fluorescence (pXRF) spectrometry, associated to geomorphology, to understand such occurrence. The studied soils are located in Muzambinho municipality, Minas Gerais State, Brazil. Oxisol profiles were characterized in the upper third (P1), middle third (P2) and lower third (P3) of the hillslope. After morphological description, soil samples were collected in the A, AB and Bo horizons of the profiles. Physical, chemical and pXRF analyses of the soils were carried out in the laboratory. Ti and Fe content (pXRF) had a high correlation with the soil textural fractions. High weathering-leaching degrees were determined, although they occur on a steep slope where younger soils (Inceptisols) would be expected in this region. The altitudinal concordance of summits observed in the more elevated surrounding areas indicates a flat paleorelief, helping to explain this unusual occurrence. The soils’ weathering degree values decreased down the hillslope, indicating silica enrichment through runoff and subsuperficial water flux in the lower landscape positions. The pXRF analyses assisted the characterization of these old soils occurring in steep relief. It provided bases for confirming their high weathering degree indexes and detected evidences of the pre-weathering of the regolith of this very old landscape.

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“…This is possible when there is covariation of primary with secondary soil attributes [18]. Although there is vast literature showing the potential of on-line measurements using vis-NIR sensor for soil mapping in regions of temperate climate [14,16,[19][20][21][22][23], tropical soils present different features, and such knowledge may not always be extrapolated [24]. The high temperature and moisture of the tropics promotes marked changes in mineralogical and biological characteristics of tropical soils when compared with soils of temperate regions, e.g., temperate soils usually feature more complex mineralogy than tropical soils and, in turn, biological activity increases notably in tropical soils compared to temperate ones [25].…”

Section: Introductionmentioning

confidence: 99%

Predictive Performance of Mobile Vis–NIR Spectroscopy for Mapping Key Fertility Attributes in Tropical Soils through Local Models Using PLS and ANN

Eitelwein¹,

Tavares

Molin

et al. 2022

Automation

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Mapping soil fertility attributes at fine spatial resolution is crucial for site-specific management in precision agriculture. This paper evaluated the performance of mobile measurements using visible and near-infrared spectroscopy (vis–NIR) to predict and map key fertility attributes in tropical soils through local data modeling with partial least squares regression (PLS) and artificial neural network (ANN). Models were calibrated and tested in a calibration area (18-ha) with high spatial variability of soil attributes and then extrapolated in the entire field (138-ha). The models calibrated with ANN obtained superior performance for all attributes. Although ANN models obtained satisfactory predictions in the calibration area (ratio of performance to interquartile range (RPIQ) ≥ 1.7) for clay, organic matter (OM), cation exchange capacity (CEC), base saturation (V), and exchangeable (ex-) Ca, it was not repeated for some of them when extrapolated into the entire field. In conclusion, robust mappings (RPIQ = 2.49) were obtained for clay and OM, indicating that these attributes can be successfully mapped on tropical soils using mobile vis–NIR spectroscopy and local calibrations using ANN. This study highlights the need to implement an independent test to assess reliability and extrapolability of previously calibrated models, even when extrapolating the models to neighboring areas.

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pXRF in tropical soils: Methodology, applications, achievements and challenges

Cited by 59 publications

References 109 publications

Portable X-ray Fluorescence Analysis of Organic Amendments: A Review

Portable X-ray Fluorescence Analysis of Organic Amendments: A Review

Study of an abnormal occurrence of Oxisols in strongly undulated relief in the south of Minas Gerais, Brazil, with support of pXRF and geomorphology

Predictive Performance of Mobile Vis–NIR Spectroscopy for Mapping Key Fertility Attributes in Tropical Soils through Local Models Using PLS and ANN

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