ABSTRACT Objective: to analyze the epidemiological and occupational profile of health workers notified for COVID-19 in Brazil, in the years 2020 and 2021. Method: this is an ecological study, which used data from the Information System of Notifiable Diseases (SINAN) and the Annual Social Information List (RAIS), from the years 2020 and 2021. Sociodemographic and occupational variables were analyzed. The prevalence rates of COVID-19 in health workers were calculated, modeled by Poisson regression in the Stata 14 software. Results: in 2020 and 2021, 35,545 health workers were affected by COVID-19. A higher prevalence of the disease was observed in females (79.0%), between 30 and 49 years (65.5%) and in blacks and browns (41.4%). Higher rates were observed in women (793.9/100,000 in 2020), young workers (839.9/100,000 in 2020), non-whites (1,497.4/100,000 in 2020) and in northern Brazil, with 1,688.1 cases per 100,000 workers in 2020. Nursing professionals, physicians and physical therapists had the highest rates of the disease in 2020 and 2021. Conclusion: there was a difference between the sexes, as well as social, racial and occupational inequities that reflect the need to expand health surveillance measures in order to ensure greater prevention, protection and assistance to health workers.

RESUMEN Objetivo: analizar el perfil epidemiológico y ocupacional de los trabajadores de la salud notificados por COVID-19 en Brasil, en los años 2020 y 2021. Método: se trata de un estudio ecológico, que utilizó datos del Sistema de Información de Enfermedades de Declaración Obligatoria (SINAN) y del Registro Anual de Información Social (RAIS), de los años 2020 y 2021. Se analizaron variables sociodemográficas y ocupacionales. Se calcularon las tasas de prevalencia de COVID-19 en trabajadores de la salud, modeladas por regresión de Poisson en el software Stata 14. Resultados: En 2020 y 2021, 35.545 trabajadores de la salud se vieron afectados por COVID-19. Se observó una mayor prevalencia de la enfermedad en el sexo femenino (79,0%), entre 30 y 49 años (65,5%) y en negros y pardos (41,4%). Se observaron tasas más altas en mujeres (793,9/100.000 en 2020), trabajadores jóvenes (839,9/100.000 en 2020), no blancos (1.497,4/100.000 en 2020) y en el norte de Brasil, con 1.688,1 casos por 100.000 trabajadores en 2020. Profesionales de enfermería, médicos y fisioterapeutas tuvieron las tasas más altas de la enfermedad en 2020 y 2021. Conclusión: hubo diferencia entre los sexos, así como desigualdades sociales, raciales y ocupacionales que reflejan la necesidad de ampliar las medidas de vigilancia de la salud para garantizar una mayor prevención, protección y asistencia a los trabajadores de la salud.

RESUMO Objetivo: analisar o perfil epidemiológico e ocupacional dos trabalhadores da saúde notificados para COVID-19 no Brasil, nos anos de 2020 e 2021. Método: trata-se de um estudo ecológico, que utilizou dados do Sistema de Informação de Agravos de Notificação (SINAN) e da Relação Anual de Informações Sociais (RAIS), dos anos de 2020 e 2021. Analisaram-se variáveis sociodemográficas e ocupacionais. Foram calculadas as taxas de prevalência de COVID-19 em trabalhadores da saúde, modeladas por Regressão de Poisson no software Stata 14. Resultados: em 2020 e 2021, 35.545 trabalhadores da saúde foram acometidos pela COVID-19. Observou-se maior prevalência da doença no sexo feminino (79,0%), entre 30 e 49 anos (65,5%) e em pretos e pardos (41,4%). Foram observadas maiores taxas em mulheres (793,9/100.000 em 2020), trabalhadores jovens (839,9/100.000 em 2020), não brancos (1.497,4/100.000 em 2020) e no Norte do Brasil, com 1.688,1 casos a cada 100.000 trabalhadores em 2020. Profissionais da enfermagem, médicos e fisioterapeutas apresentaram as maiores taxas da doença em 2020 e 2021. Conclusão: observou-se diferença entre os sexos, bem como iniquidades sociais, raciais e ocupacionais que traduzem a necessidade de ampliar medidas de vigilância em saúde, a fim de garantir maior prevenção, proteção e assistência aos trabalhadores de saúde.

Este artigo é um estudo de caso sobre a trajetória eleitoral e organizacional do Partido da Social Democracia Brasileira (PSDB) no estado de São Paulo entre 1994 e 2018. O objetivo foi identificar como o partido conserva sua dominância, com sete vitórias consecutivas para o governo do estado e maior número de prefeituras conquistadas dentre os demais partidos desde 1996. A hipótese é que a organização interna do PSDB paulista foi essencial para que o partido mantivesse seu sucesso eleitoral. A metodologia envolveu a coleta de dados eleitorais, que possibilitaram mensurar o desempenho eleitoral do partido para os cargos de vereador, prefeito e governador, além da realização de entrevistas para a compreensão das estratégias do partido. Os resultados demonstram uma organização interna fortemente institucionalizada, com uma Executiva estadual capaz de fiscalizar todos os municípios, atender a demandas e mostrar-se presente ao eleitorado.

Abstract This article is a case study about the PSDB's electoral and organizational trajectory in the state of São Paulo between 1994 and 2018. The aim is to identify how the political party maintains its dominance, with seven consecutive victories for the state government and greater number of city halls won among other parties since 1996. This work is based on the hypothesis that PSDB’s internal organization in São Paulo was essential for the party to remain dominant during the analyzed period. The methodology involved electoral data, thus we could measure the party's electoral success for the positions of councilor, mayor and governor, as well as interviews for an understanding of the party's strategies. The results show a party's organizational structure under strong institutionalization, with a state executive capable of inspecting all municipalities in the state, attending demands and showing itself as a present party to the electorate.

Resumen Este artículo es un estudio de caso sobre la trayectoria electoral y organizativa del PSDB en el estado de São Paulo entre 1994 y 2018. El objetivo es identificar cómo el partido conserva su dominio durante el período propuesto, con siete victorias consecutivas para el gobierno estatal y el mayor número de los ayuntamientos conquistados entre los otros partidos desde 1996. La hipótesis es que la organización interna del PSDB de São Paulo es esencial para que el partido mantuviera su éxito electoral. La metodología implicó la recopilación de datos electorales, lo que permitió medir el éxito electoral del partido en el estado para los cargos de concejal, alcalde y gobernador, además de realizar entrevistas bajo un modelo semiestructurado para comprender las estrategias del partido. Los resultados demuestran una organización interna altamente institucionalizada, con una Ejecutiva estatal capaz de inspeccionar todos los municipios, satisfacer las demandas y mostrarse como un partido presente en el electorado. Así, el PSDB-SP se convirtió en el partido político más grande del estado en términos electorales.

Résumé Cet article présente une étude de cas sur la trajectoire électorale et organisationnelle du PSDB dans l’État de São Paulo (SP) entre 1994 et 2018. L’objectif est de déterminer comment le parti maintient sa dominance pendant la période proposée, avec sept victoires consécutives pour le gouvernement de l’État et le plus de mairies gagnées parmi les autres partis depuis 1996. L’hypothèse est que l’organisation interne du PSDB-SP a été essentielle pour que le parti maintienne son succès électoral. La méthodologie a consisté à recueillir des données électorales, ce qui a permis de mesurer le succès électoral du parti dans l’État pour les postes de conseiller municipal, de maire et de gouverneur de l’État, en plus de mener des entretiens semi-directifs pour comprendre les stratégies du parti. Les résultats démontrent une organisation interne fortement institutionnalisée, avec un exécutif d’État capable d’inspecter toutes les municipalités, de répondre aux demandes et de se montrer un parti présent à l’électorat. Ainsi, le PSDB-SP est devenu le plus grand parti politique de l’État en termes électoraux.

RESUMO Embora o prefeito detenha o cargo eletivo mais importante nos municípios brasileiros, sua função demanda apoio legislativo para implementar sua agenda. Neste artigo, analisamos alguns recursos que as candidaturas dos prefeitos eleitos mobilizam para obter o maior potencial de apoio legislativo possível. Partimos de duas possibilidades: ou o candidato eleito transfere sua popularidade aos seus apoiadores na disputa proporcional; ou se coliga com vários partidos. A primeira opção sustenta-se no efeito coattail; a segunda, nos seguintes aspectos institucionais: fragmentação no Legislativo e concentração de candidatos no Executivo. Amparados por dados municipais de coligação eleitoral, investigamos cinco eleições (2000-2016). Nossos resultados sugerem que tanto a popularidade transferida pelo prefeito eleito, quanto o número de partidos na coligação majoritária impactam positivamente no potencial de apoio legislativo. Por fim, indicam que não há interação entre estes dois efeitos, demonstrando que ambas as estratégias são alternativas entre si.

ABSTRACT Although the mayor holds the most important elective office in Brazilian municipalities, his role requires legislative support to implement its agenda. In this article, we analyze some resources that mayoral candidates who have been elected mobilized to obtain the greatest potential for legislative support. We started from two possibilities: either the elected candidate transfers his popularity to his supporters in the proportional dispute; or if he forms a coalition with several parties. The first option is based on the coattail effect; the second, in the following institutional aspects: fragmentation in the Legislative and concentration of candidates in the Executive. Using municipal electoral coalition data, we investigated five elections (2000-2016). Our results suggest that both the popularity transferred by the elected mayor and the number of parties in the majority coalition positively affect the potential for legislative support. Finally, the data indicate that there is no interaction between these two effects, demonstrating that both strategies are unrelated alternatives.

RESUMEN Aunque el alcalde ostenta el cargo electivo más importante en los municipios brasileños, su función demanda del apoyo legislativo para implementar su agenda. En este artículo, analizamos algunos recursos que movilizan las propuestas de los alcaldes electos para obtener el mayor potencial de apoyo legislativo posible. Partimos de dos posibilidades: o el candidato electo transfiere su popularidad a sus partidarios en la disputa en el sistema proporcional; o se asocia con varios partidos. La primera opción se sustenta en el efecto coattail; la segunda, en los siguientes aspectos institucionales: fragmentación en el Legislativo y concentración de candidatos en el Ejecutivo. Amparados por datos municipales de coalición electoral, investigamos cinco elecciones (2000-2016). Nuestros resultados sugieren que tanto la popularidad transferida por el alcalde electo, como el número de partidos en la coalición mayoritaria impactan positivamente en el potencial de apoyo legislativo. Finalmente, indican que no hay interacción entre estos dos efectos, demostrando que ambas estrategias son alternativas entre sí.

RÉSUMÉ Bien que le maire occupe le poste électif le plus important dans les municipalités brésiliennes, son rôle nécessite un soutien législatif pour mettre en œuvre son programme. Dans cet article, on examine certaines ressources que les candidatures des candidats à la mairie mobilisent pour obtenir le plus grand potentiel de soutien législatif possible. On part de deux possibilités: ou le candidat élu transfère sa popularité à ses partisans dans le différend proportionnel; ou il s’associe avec plusieurs partis. La première option est basée sur l’effet coattail; la seconde, sur les aspects institutionnels suivants: fragmentation du législatif et concentration des candidats à l’exécutif. Forts des données des coalitions électorales municipales, nous avons enquêté sur cinq élections (2000-2016). Nos résultats suggèrent que tant la popularité transférée par le maire élu que le nombre de partis de la coalition majoritaire ont un impact positif sur le potentiel de soutien législatif. Enfin, ils indiquent qu’il n’y a pas d’interaction entre ces deux effets, démontrant que les deux stratégies sont des alternatives l’une à l’autre.

Abstract Portable X-ray fluorescence (pXRF) spectrometry offers valuable information for prediction models of soil fertility attributes spatial variation, although this approach is yet scarce in tropical regions. This study aims to predict and build spatial variability maps of soil pH, remaining phosphorus (P-Rem), soil organic matter (SOM) and sum of bases (SB) using pXRF results through stepwise multiple linear regression (SMLR) and Random Forest (RF) in a highly variable tropical area. Composite samples from soil A horizon were collected at 90 points throughout the campus of the Federal University of Lavras, Minas Gerais, Brazil, for pH, P-Rem, SOM, SB and pXRF analyses. RF predictions showed the highest accuracies, especially for P-Rem and SB (R² values of 0.66 and 0.55, respectively). Attributes that showed higher R² in punctual predictions also exhibited higher R² in spatial predictions. Data obtained from pXRF in tandem with RF can be used to assist prediction models for soil fertility attributes, consequently enabling the digital mapping of such attributes and helping to improve the knowledge about the spatial variability of such attributes in soils of tropical climate. This technique can therefore assist in the identification and orientation of adequate management practices in tropical agricultural practices.

RESUMO Latossolos são os principais solos do Brasil e classicamente ocorrem em superfícies geomórficas suavizadas e estáveis. No entanto, no Sul de Minas Gerais, Latossolos têm sido observados em relevo forte ondulado, uma condição rara para estes solos nesta região fisiográfica. Este trabalho teve como objetivo acessar a dinâmica elementar e o relevo com uso de espectrometria de fluorescência de raios-X portátil (pXRF), em associação à geomorfologia, para entender tal ocorrência. Os solos estudados estão localizados no município de Muzambinho, Estado de Minas Gerais, Brasil. Perfis de Latossolo foram caracterizados no terço superior (P1), terço médio (P2) e terço inferior (P3) da encosta. Após a descrição morfológica, amostras de solo foram coletadas nos horizontes A, AB e Bw dos perfis. Foram realizadas análises físicas, químicas e espectrométricas dos solos em laboratório. Os teores de Ti e Fe (pXRF) tiveram alta correlação com as frações texturais dos solos. Foram encontrados altos graus de intemperismo-lixiviação dos Latossolos, embora ocorram em encosta íngreme onde solos mais jovens (Cambissolos) seriam esperados. A concordância de altitude dos topos observada nas áreas circundantes mais elevadas indica um paleorrelevo plano, ajudando a explicar esta ocorrência anormal. Os valores dos índices de intemperismo dos solos diminuíram ao longo da encosta, indicando o enriquecimento de sílica por escoamento superficial e fluxo de água subsuperficial nas posições mais baixas da paisagem. As análises de pXRF ajudaram na caracterização destes solos velhos em topografia forte ondulada. O equipamento forneceu bases para confirmação dos seus altos graus de intemperismo, além de detectar evidências do pré-intemperismo do regolito dessa paisagem muito antiga.

ABSTRACT 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.

ABSTRACT Sorption of selenate (SeO 4 2- ) and selenite (SeO 3 2- ) is poorly understood in Brazilian agroecosystems, especially in soils from agricultural areas containing different contents of competing anions, such as sulfate (SO 4 2- ). This study aimed to assess the sorption behavior of selenate and selenite at different soil layers of a tropical soil treated with different rates of agricultural gypsum (thus, containing different contents of sulfate), collected under a coffee plantation. Soil samples from an experimental area where phosphogypsum has been previously applied at different rates (0, 7, 14, and 56 t ha -1 ) were taken at the following soil layers: 0.15-0.25, 0.35-0.45, and 1.25-1.35 m. Adsorption experiments were carried out adding 20 mL of solutions containing 100 and 500 μg L -1 of selenate and 10 and 15 mg L -1 of selenite to 2 grams of soil. Desorption experiments were also performed using a soil:solution ratio of 1:10. Adsorption of selenate increased with soil depth and decreased upon increasing sulfate contents in the soil, by contrast, selenite was consistently adsorbed at higher contents - when compared with selenate - at any soil depth and its sorptive behavior was not affected by the presence of sulfate. Furthermore, selenite was less desorbed than selenate under all conditions. In conclusion, selenite is much more retained in tropical soils and less available to plants than selenate. Also, although sulfate has shown to be able to hinder selenate retention, it has no substantial effect on the sorption behavior of selenite in tropical agroecosystems.

RESUMO A espectrometria portátil de fluorescência de raios-X (pXRF) tem sido útil em todo o mundo para determinar o teor dos elementos no solo em condições de campo e de laboratório. No entanto, os resultados obtidos em campo podem ser influenciados por vários fatores, como umidade (U), textura (T) e matéria orgânica do solo (MOS). Assim, o objetivo deste trabalho foi criar modelos matemáticos lineares para a conversão dos teores dos elementos obtidos por pXRF em campo para resultados obtidos em laboratório, i.e., na Terra Fina Seca ao Ar (TFSA), utilizando U, T e MOS como variáveis auxiliares, uma vez que elas influenciam as leituras. As análises com pXRF foram realizadas em 12 perfis de solo com diferentes materiais de origem, seguidas por coleta de 59 amostras. Leituras com pXRF foram realizadas também em laboratório em amostras de TFSA. Os dados de pXRF obtidos em campo foram utilizados sozinhos ou combinados aos dados de U, T e MOS como variáveis auxiliares, para criar modelos de regressão linear para predição dos resultados de pXRF em TFSA. A acurácia dos modelos foi calculada pelo método leave-one-out cross-validation. À exceção de elementos mais leves, as leituras de campo com pXRF subestimaram o teor total dos elementos. Modelos de predição incluindo T apresentaram maior acurácia na predição de Al2O3, SiO2, V, Ti e Zr, enquanto a predição dos teores de Fe e K2O foi insensível à adição das variáveis auxiliares. A melhora relativa (MR) nos modelos de predição foi maior nas predições de SiO2 (T+MOS: MR = 22,29%), V (U+T: MR = 18,90%) e Ti (T+MOS: MR = 11,18%). Este trabalho demonstrou que é possível a correção dos dados de pXRF obtidos em campo através de modelos de regressão linear.

ABSTRACT Portable X-ray fluorescence (pXRF) spectrometry has been useful worldwide for determining soil elemental content under both field and laboratory conditions. However, the field results are influenced by several factors, including soil moisture (M), soil texture (T) and soil organic matter (SOM). Thus, the objective of this work was to create linear mathematical models for conversion of Al2O3, CaO, Fe, K2O, SiO2, V, Ti and Zr contents obtained by pXRF directly in field to those obtained under laboratory conditions, i.e., in air-dried fine earth (ADFE), using M, T and SOM as auxiliary variables, since they influence pXRF results. pXRF analyses in field were performed on 12 soil profiles with different parent materials. From them, 59 samples were collected and also analyzed in the laboratory in ADFE. pXRF field data were used alone or combined to M, T and SOM data as auxiliary variables to create linear regression models to predict pXRF ADFE results. The models accuracy was assessed by the leave-one-out cross-validation method. Except for light-weight elements, field results underestimated the total elemental contents compared with ADFE. Prediction models including T presented higher accuracy to predict Al2O3, SiO2, V, Ti and Zr, while the prediction of Fe and K2O contents was insensitive to the addition of the auxiliary variables. The relative improvement (RI) in the prediction models were greater in predictions of SiO2 (T+SOM: RI=22.29%), V (M+T: RI=18.90%) and Ti (T+SOM: RI=11.18%). This study demonstrates it is possible to correct field pXRF data through linear regression models.

ABSTRACT Sulfuric acid digestion analyses (SAD) provide useful information to environmental studies, in terms of the geochemical balance of nutrients, parent material uniformity, nutrient reserves for perennial crops, and mineralogical composition of the soil clay fraction. Yet, these analyses are costly, time consuming, and generate chemical waste. This work aimed at predicting SAD results from portable X-ray fluorescence (pXRF) spectrometry, which is proposed as a “green chemistry” alternative to the current SAD method. Soil samples developed from different parent materials were analyzed for soil texture and SAD, and scanned with pXRF. The SAD results were predicted from pXRF elemental analyses through simple linear regressions, stepwise multiple linear regressions, and random forest algorithm, with and without incorporation of soil texture data. The modeling was developed with 70 % of the data, while the remaining 30 % was used for validation through calculation of R2, adjusted R2, root mean square error, and mean error. Simple linear regression can accurately predict SAD results of Fe2O3 (R2 0.89), TiO2 (R2 0.96), and P2O5 (R2 0.89). Stepwise regressions provided accurate predictions for Al2O3 (R2 0.87) and Ki - molar weathering index (SiO2/Al2O3) (R2 0.74) by incorporating soil texture data, as well as for SiO2 (R2 0.61). Random forest also provided adequate predictions, especially for Fe2O3 (R2 0.95), and improved results of Kr - molar weathering index (SiO2/(Al2O3 + Fe2O3)) (R2 0.66), by incorporation of soil texture data. Our findings showed that the SAD results could be accurately predicted from pXRF data, decreasing costs, time and the production of laboratory waste.

ABSTRACT: Different uses of soil legacy data such as training dataset as well as the selection of soil environmental covariables could drive the accuracy of machine learning techniques. Thus, this study evaluated the ability of the Random Forest algorithm to predict soil classes from different training datasets and extrapolate such information to a similar area. The following training datasets were extracted from legacy data: a) point data composed of 53 soil samples; b) 30 m buffer around the soil samples, and soil map polygons excluding: c) 20 m; and d) 30 m from the boundaries of polygons. These four datasets were submitted to principal component analysis (PCA) to reduce multidimensionality. Each dataset derived a new one. Different combinations of predictor variables were tested. A total of 52 models were evaluated by means of error of models, prediction uncertainty and external validation for overall accuracy and Kappa index. The best result was obtained by reducing the number of predictors with the PCA along with information from the buffer around the points. Although Random Forest has been considered a robust spatial predictor model, it was clear it is sensitive to different strategies of selecting training dataset. Effort was necessary to find the best training dataset for achieving a suitable level of accuracy of spatial prediction. To identify a specific dataset seems to be better than using a great number of variables or a large volume of training data. The efforts made allowed for the accurate acquisition of a mapped area 15.5 times larger than the reference area.

RESUMO Espectrômetria portátil de fluorescência de raios-X (pXRF) tem sido crescentemente adotada para estudos sobre solos. Este trabalho objetivou caracterizar efeitos do manejo do solo no teor de elementos químicos detectados pelo pXRF em Cambissolos manejados e não manejados e avaliar o potencial de uso de dados do pXRF para gerar modelos de predição da fertilidade do solo. Amostras foram coletadas em floresta nativa, Cerrado nativo, cafeeiros com 1 e 5 anos de implantação e eucalipto, nos horizontes A, B e C. Atributos de fertilidade do solo foram determinados por análises laboratoriais, enquanto o teor dos elementos foi obtido pelo pXRF. Dados do pXRF foram utilizados para modelagem (regressões) e validação de atributos de fertilidade do solo, além da necessidade de calagem (NL), com ou sem distinção entre áreas manejadas e não manejadas. Práticas de manejo dos cafeeiros aumentaram os teores totais de Sr, CaO, P2O5, Cu e Zn. Os teores de CaO foram eficientes para predição de teores trocáveis de Ca2+ (R2 = 0,91), pH (R2 = 0,88) e saturação por bases (R2 = 0,89) nas áreas manejadas. Modelos gerais foram adequados para predizer teores trocáveis de Ca2+ (R2 = 0,92), pH (R2 = 0,85) e saturação por bases (R2 = 0,90). Modelos para áreas não manejadas foram menos eficazes. O pXRF detectou modificações no teor dos elementos causadas pelas práticas de manejo e possibilitou predições adequadas de atributos relacionados à fertilidade do solo.

ABSTRACT Portable X-ray fluorescence (pXRF) spectrometry has been increasingly adopted for varying studies worldwide. This work aimed at characterizing effects of soil management on the content of chemical elements detected by pXRF in managed and unmanaged areas of Inceptisols, and evaluating the potential of using pXRF data to generate prediction models for soil fertility attributes, evaluating the effect of land uses on such models. Samples were collected in A, B, and C horizons of soils under native forest, native Cerrado, coffee crops with 1 and 5 years of implantation and eucalyptus. Soil fertility attributes were determined through laboratory analyses, whereas, elemental contents were obtained through pXRF analysis. PXRF data were used for modeling (regressions) and validation of soil fertility attributes and necessity of lime (NL) application, with or without distinction between managed and unmanaged areas. Management practices on coffee crops increased the levels of Sr, CaO, P2O5, Cu, and Zn. CaO content was efficient for prediction of exchangeable Ca2+ contents (R2 = 0.91), pH (R2 = 0.88), base saturation (R2 = 0.89) in managed areas. General models presented adequate results to predict exchangeable Ca2+ (R2 = 0.92), pH (R2 = 0.85), and base saturation (R2 = 0.90). Models for unmanaged areas were less effective. PXRF detected modifications in elemental contents caused by management practices and provided reliable predictions of soil fertility attributes.

ABSTRACT: The estimation of soil physical and chemical properties at non-sampled areas is valuable information for land management, sustainability and water yield. This work aimed to model and map soil physical-chemical properties by means of knowledge-based digital soil mapping approach as a study case in two watersheds representative of different physiographical regions in Brazil. Two watersheds with contrasting soil-landscape features were studied regarding the spatial modeling and prediction of physical and chemical properties. Since the method uses only one value of soil property for each soil type, the way of choosing typical values as well the role of land use as a covariate in the prediction were tested. Mean prediction error (MPE) and root mean square prediction error (RMSPE) were used to assess the accuracy of the prediction methods. The knowledge-based digital soil mapping by means of fuzzy logics is an accurate option for spatial prediction of soil properties considering: 1) lesser intense sampling scheme; 2) scarce financial resources for intensive sampling in Brazil; 3) adequacy to properties with non-linearity distribution, such as saturated hydraulic conductivity. Land use seems to influence spatial distribution of soil properties thus, it was applied in the soil modeling and prediction. The way of choosing typical values for each condition varied not only according to the prediction method, but also with the nature of spatial distribution of each soil property.