ABSTRACT Objective: The objective of this study was to analyze feeding behavior in children with autism spectrum disorder. Methods: Twenty-one children with autism spectrum disorder (ASD) participated in this study, aged 2 to 14 years old, of both sexes. A questionnaire on feeding behavior was applied to the 21 parents and/or responsible of the children. This instrument consists of 53 questions, distributed in the following categories: Motricity in chewing; Food selectivity; Behavioral aspects; Gastrointestinal symptoms; Sensory sensitivity and Skills in meals. Results: The analysis of the data obtained reveals that children with ASD showed greater changes in eating behavior in the categories Food selectivity (34.4%), Behavioral aspects (27.1%) and Motricity in mastication (21.9%). And there was a correlation between the chewing motricity category with all other categories. There was also a correlation between food selectivity with behavioral aspects and behavioral aspects with sensory sensitivity and mealtime skills. Conclusion: Therefore, it is possible to observe that in the eating behavior of children with autism spectrum disorder there is a tendency towards food selectivity, habitual behaviors during meals and motor difficulties with regard to chewing and food intake.

RESUMO Objetivo: O objetivo deste estudo foi analisar o comportamento alimentar de crianças e adolescentes com transtorno do espectro autista. Métodos: Participaram deste estudo 21 crianças e adolescentes com TEA, na faixa etária de 2 a 14 anos de idade, de ambos os sexos. Foi aplicado um questionário sobre o comportamento alimentar com os 21 pais e/ou responsáveis das crianças. Esse instrumento é composto por 53 questões, distribuídas nas seguintes categorias: Motricidade na mastigação; Seletividade alimentar; Aspectos comportamentais; Sintomas gastrointestinais; Sensibilidade sensorial e Habilidades nas refeições. Resultados: A análise dos dados obtidos revela que as crianças com TEA apresentaram maiores alterações no comportamento alimentar nas categorias Seletividade alimentar (34,4%), Aspectos comportamentais (27,1%) e Motricidade na mastigação (21,9%). E houve correlação entre a categoria Motricidade na mastigação com todas as outras categorias. Houve também correlação entre seletividade alimentar com aspectos comportamentais e aspectos comportamentais com sensibilidade sensorial e habilidades nas refeições. Conclusão: Portanto, é possível observar que, no comportamento alimentar de crianças e adolescentes com TEA, há uma tendência a seletividade alimentar, comportamentos habituais durante as refeições e dificuldades motoras no que se refere à mastigação e à ingestão dos alimentos.

Abstract Background: The association of scaffolds to repair extensive bone defects can contribute to their evolution and morphophysiological recomposition. The incorporation of particulate biomaterials into three-dimensional fibrin bioproducts together with photobiomodulation therapy (PBM) has potential and can improve regenerative medicine procedures. The objective of this experiment was to evaluate the effects of PBM therapy on critical size defects filled with xenogenic bone substitute associated with fibrin biopolymer. Methods: A critical defect of 8 mm was performed in 36 Wistar male adult rats that were divided into four groups. Groups BC and BC-PBM were defined as controls with defects filled by a clot (without or with PBM, respectively) and groups XS and XS-PBM that comprised those filled with biocomplex Bio-OssTM in association with fibrin biopolymer. PBM was applied immediately after the surgery and three times a week every other day, with the parameters: wavelength of 830 nm, energy density 6.2 J/cm2, output power 30 mW, beam area of 0.116 cm2, irradiance 0.258,62 W/cm2, energy/point 0.72 J, total energy 2.88 J. Fourteen and 42 days after the surgery, animals were euthanatized and subjected to microtomography, qualitative and quantitative histological analysis. Results: The BC-PBM and XS-PBM groups had a similar evolution in the tissue repair process, with a higher density of the volume of new formed bone in relation to the groups without PBM (p = 0.04086; p = 0.07093, respectively). Intense vascular proliferation and bone deposition around the biomaterial particles were observed in the animals of the groups in which biocomplex was applied (XS and XS-PBM). Conclusion: PBM therapy allowed an improvement in the formation of new bone, with a more organized deposition of collagen fibers in the defect area. Biocomplex favored the insertion and permanence of the particulate material in bone defects, creating a favorable microenvironment for accelerate repair process.

ABSTRACT Purpose: To evaluate in-vivo degradation of two bioabsorbable interference screws. Methods: Twenty-two crossbred Santa Inês ewes were used. A poly-DL-lactide (PDLLA) screw (70%/30%) was inserted in the right pelvic limb, and a PDLLA screw (70%) + β-tri-calcium phosphate (β-TCP) (30%) in the left pelvic limb. Animals were euthanized at one, four, seven and a half and 18 months after surgery. Plain radiography, computed tomography (CT), microCT, and histological analysis were accomplished. Results: PDLLA screw was hypodense at all evaluation moments, but with progressive density increase along the central axis, whereas PDLLA/β-TCP was initially hyperdense and progressively lost this characteristic. No adverse reactions were observed on histological evaluation. Conclusions: The inclusion of β-TCP favors screw degradation since the PDLLA/β-TCP screws evidenced a more intense degradation process than the PDLLA screws at the last evaluation. PDLLA screws showed higher bone production, evident around the screw thread, inside the lateral perforations, and in the central canal, whereas the PDLLA/β-TCP screws presented less bone tissue at the implantation site.

ABSTRACT. Pearson's correlation and spatial variability are tools that can be used to help one understand the process of losses in the mechanical harvesting of cotton. Therefore, the objective of this study was to model the spatial distribution and map the losses of mechanical cotton harvest using geostatistics and to correlate the losses with agronomic variables using Pearson’s correlation. The experiment was conducted in Itiquira and Lucas do Rio Verde, Mato Grosso State, Brazil. At each sampling point, the evaluated variables were agronomic plant variables and cotton losses in the soil and the plant (divided into lower, medium and upper thirds) and the sum total of losses. The highest losses in cotton harvest occurred in the lower third and on the soil, both of which exhibit a spatial dependence model, according to geostatistics, demonstrating that they do not occur in a randomized process and are related to the specific plant. There was a relationship between the plant populations with losses in the cotton crop. The plant population can influence the spatial dependence of losses.

ABSTRACT The identification of erosion-susceptible areas is fundamental for the adoption of soil conservation practices. Thus, the best way to estimate the spatial pattern of soil erosion must be identified, in which the process uncertainties are also taken into consideration. The purpose of this study was to evaluate the spatial and temporal uncertainty of soil loss under two scenarios of sugarcane harvest management: green cane (GC) and burnt cane (BC). The study was carried out on a 200-ha area, in Tabapuã, São Paulo State, Brazil. A regular 626-point sampling grid was established in the area, with equidistant intervals of 50 m and a final plant density of about 3.3 samples per ha. The probability that the soil loss would exceed the tolerable limit of 6.67 t ha-1 yr-1 was estimated for each management scenario and after the five harvests. The temporal uncertainty was determined by integrating the estimated annual probabilities, representing the harvests. Areas with soil loss risks above the threshold were identified based on probability maps, generated from the individual and combined dichotomous variables. Soil losses from the BC were highest, during all five harvests. With the exception of the 5th harvest and the entire cultivation cycle under GC, all soil loss estimates were spatially dependent. From the 4th harvest under GC, the probability of the soil loss exceeding the threshold was above 80 % in zero percent of the area, whereas, for BC, the probability exceeded 80 % in 40 % of the area. The production cycle allowed the delimitation of priority areas for the adoption of conservation practices in each management. In the BC, areas with steeper slopes were more likely to exceed the threshold with lower uncertainties.

Resumo O objetivo deste trabalho foi avaliar o uso da susceptibilidade magnética para caracterizar a variabilidade espacial dos atributos do solo e identificar áreas com diferentes potenciais de produção de cana-de-açúcar (Saccharum spp.). Foram coletadas amostras em 110 pontos (1 por cada 7 ha), nas camadas de 0,00-0,20 e 0,20-0,40 m, para determinação da suscetibilidade magnética e de atributos físicos e químicos do solo. O teor de fibra, a polarização da sacarose (POL) e a produtividade da cana-de-açúcar foram determinados em 33 pontos. O modelo de variabilidade espacial da susceptibilidade magnética foi 63 e 22% mais acurado em delimitar o potencial do solo para produção da cana-de-açúcar que os atributos físicos e químicos do solo, nas camadas de 0,00-0,20 e de 0,20-0,40 m de profundidade, respectivamente. O mapa da variabilidade espacial da susceptibilidade magnética apresentou forte correlação com o conteúdo de argila (0,83 e 0,89, respectivamente, para as camadas) e de areia (-0,84 e -0,88); moderada correlação com a matéria orgânica (-0,25 e -0,35), a soma de bases (-046 e 0,37), a capacidade de troca catiônica (0,22 e 0,47), o pH (-0,52 e 0,13) e a POL (0,43 e 0,53); e fraca correlação com a produtividade da cana-de-açúcar (0,26 e 0,23). A susceptibilidade magnética pode ser utilizada para caracterizar a variabilidade espacial dos atributos do solo e para identificar áreas com diferentes potenciais para produção de cana-de-açúcar.

Abstract The objective of this work was to evaluate the use of magnetic susceptibility for characterizing the spatial variability of soil attributes and identifying areas with different potentials for sugarcane (Saccharum spp.) production. Samples were collected at 110 points (1 per 7 ha) in the layers of 0.00-0.20 and 0.20-0.40 m, to determine the magnetic susceptibility and physical and chemical attributes of the soil. Fiber content, sucrose polarization (POL), and sugarcane yield were determined in 33 points. The spatial variability model for magnetic susceptibility was 63 and 22% more accurate in delimiting soil potential for sugarcane production than soil physical and chemical attributes at the 0.0-0.2 and 0.2-0.4-m layers, respectively. The spatial variability map for magnetic susceptibility was strongly correlated with clay (0.83 and 0.89, respectively, for the layers) and sand contents (-0.84 and -0.88); moderately correlated with organic matter (-0.25 and -0.35), sum of bases (-0.46 and 0.37), cation exchange capacity (0.22 and 0.47), pH (-0.52 and 0.13), and POL (0.43 and 0.53); and weakly correlated with sugarcane yield (0.26 and 0.23). Magnetic susceptibility can be used to characterize the spatial variability of soil attributes and to identify areas with different potentials for sugarcane production.

ABSTRACTSoil CO2 emissions (fCO2) in agricultural areas have been widely studied in global climate change research, but its characterization and quantification are restricted to small areas. Because spatial and time variability affect emissions, tools need to be developed to predict fCO2 for large areas. This study aimed to investigate soil magnetic susceptibility (MS) and its correlation with fCO2 in an agricultural environment. The experiment was carried out on a Typic Eutrudox located in Guariba-SP, Brazil. Results showed that there was negative spatial correlation between fCO2 and the magnetic susceptibility of Air Dried Soil (MSADS) up to 34.3 m distant. However, the fCO2 had no significant correlation with MSADS, magnetic susceptibility of sand (MSSAND) nor clay (MSCLAY). However, MSADS could be a supplemental mean of identifying regions of high fCO2 potential over large areas.

A avaliação da incerteza espacial das predições das perdas de nutrientes por erosão, associada aos modelos de paisagem, é importante ferramenta na análise e no planejamento conservacionista do solo. O objetivo deste trabalho foi avaliar a incerteza espacial e o local na predição das taxas de empobrecimento do solo por nutrientes (P, K, Ca e Mg) em razão da erosão hídrica em dois sistemas de colheita da cana-de-açúcar (cana crua e queimada), utilizando-se a simulação sequencial gaussiana (SSG). O estudo foi realizado em uma área de 200 ha, localizada em Tabapuã, Estado de São Paulo, sudeste do Brasil. Uma malha de amostragem regular foi estabelecida na área, com intervalos equidistantes de 50 m, totalizando 626 pontos. A taxa de empobrecimento do solo foi calculada com base na relação entre concentração dos nutrientes no sedimento erodido e os atributos químicos do solo original, ponto a ponto. Os dados foram submetidos à análise estatística descritiva e geoestatística. A taxa média de empobrecimento do solo para todos os nutrientes avaliados foi superior no cenário de cana queimada em relação ao cenário de cana crua (teste t-Student; p<0,05). Em ambos os cenários, a ordem da perda dos nutrientes foi: Ca>Mg>K>P. Áreas com maior taxa de empobrecimento do solo foram relacionadas à maior declividade da paisagem. As menores incertezas estão associadas às áreas com maiores taxas de empobrecimento do solo e declividades. Por sua vez, as maiores incertezas estão associadas às áreas de transição entre as pedoformas côncava e convexa.

The assessment of spatial uncertainty in the prediction of nutrient losses by erosion associated with landscape models is an important tool for soil conservation planning. The purpose of this study was to evaluate the spatial and local uncertainty in predicting depletion rates of soil nutrients (P, K, Ca, and Mg) by soil erosion from green and burnt sugarcane harvesting scenarios, using sequential Gaussian simulation (SGS). A regular grid with equidistant intervals of 50 m (626 points) was established in the 200-ha study area, in Tabapuã, São Paulo, Brazil. The rate of soil depletion (SD) was calculated from the relation between the nutrient concentration in the sediments and the chemical properties in the original soil for all grid points. The data were subjected to descriptive statistical and geostatistical analysis. The mean SD rate for all nutrients was higher in the slash-and-burn than the green cane harvest scenario (Student’s t-test, p<0.05). In both scenarios, nutrient loss followed the order: Ca>Mg>K>P. The SD rate was highest in areas with greater slope. Lower uncertainties were associated to the areas with higher SD and steeper slopes. Spatial uncertainties were highest for areas of transition between concave and convex landforms.

O objetivo deste trabalho foi avaliar a possibilidade de se mapear o fósforo adsorvido por meio da avaliação da cor e da suscetibilidade magnética do solo. O experimento foi realizado em área de cana-de-açúcar com 380 ha, que compreendia quatro tipos de Latossolos, com diferentes texturas e fertilidades naturais. Foram coletadas 241 amostras de solo, na profundidade de 0,00-0,25 m. O índice de avermelhamento do solo foi calculado a partir dos valores de matiz, valor e croma das amostras, obtidos com espectroscopia de reflectância difusa. Foram ajustados modelos de regressão entre o fósforo adsorvido e a suscetibilidade magnética ou o índice de avermelhamento dos solos. A dependência espacial dos dados foi avaliada por meio de geoestatística. A suscetibilidade magnética correlaciona-se significativamente ao fósforo adsorvido, o que possibilita seu uso como componente de funções de pedotransferência para quantificação indireta do fósforo adsorvido ao solo. O índice de avermelhamento e a suscetibilidade magnética apresentam dependência espacial com o fósforo adsorvido. A suscetibilidade magnética e o índice de avermelhamento dos solos, avaliado pela espectroscopia de reflectância difusa, podem auxiliar no mapeamento e na identificação de áreas com diferentes potenciais de adsorção de fósforo.

The objective of this work was to evaluate the possibility of mapping adsorbed phosphorus through soil color and magnetic susceptibility. The experiment was done in a 380-ha sugarcane area, which included four types of Oxisols, with different texture and natural fertility. Two hundred and forty-one soil samples were collected at 0.00-0.25-m depth. The soil redness index was calculated from sample values of hue, value, and chroma, obtained with diffuse reflectance spectroscopy. Regression models were adjusted between adsorbed phosphorus and soil magnetic susceptibility or redness index. Data spatial dependence was evaluated with geostatistics. Magnetic susceptibility is significantly correlated to adsorbed phosphorus, which allows it to be used as a component in pedotransfer functions for indirect quantification of soil adsorbed phosphorus. The redness index and the magnetic susceptibility show spatial dependency with adsorbed phosphorus. Soil magnetic susceptibility and redness index, evaluated with diffuse reflectance spectroscopy, can aid in the mapping and identification of areas with different phosphorus adsorption potential.

Soil CO2 emission (FCO2) is one of the main sources of carbon release into the atmosphere. Moreover, FCO2 is related to soil attributes governing the transfer of gases from soil to the atmosphere. This study aimed firstly to describe the spatial variability of hematite (Hm), goethite (Gt), iron extracted with sodium dithionite-citrate-bicarbonate (Fed) contents, soil CO2 emission (FCO2) and free-water porosity (FWP) and secondly, to develop statistical models to predict the above mentioned factors in an Oxisol cultivated under manual harvesting of sugarcane (Saccharumspp.) in southeastern Brazil. The study was conducted on an irregular 50 m × 50 m grid containing 89 points, each 0.5-10 m apart. The 0-0.1 m soil layer at each sampling point was used to assess soil FCO2, moisture and total pore volume. The results were subjected to descriptive statistical and geostatistical analyses using auto- and cross-semivariograms. All soil attributes exhibited a spatial dependence structure and the experimental semivariograms fitted spherical and exponential models. The Gt content was the individual attribute that exhibited the highest linear and spatial correlation, especially with FCO2. We were able to use diffuse reflectance spectroscopy to map large areas, which allows for easy identification and estimation of soil attributes such as FCO2 and FWP. Geostatistical techniques faciltate the interpretation of spatial relationships between soil respiration and the examined properties.

A escassez de informações sobre o comportamento espacial dos atributos dos solos na região amazônica tem sido preocupação de muitos pesquisadores. Assim, este trabalho teve como objetivos avaliar a variabilidade espacial de atributos químicos do solo e determinar a densidade amostral mínima para caracterizar a variabilidade desses atributos em cinco ambientes amazônicos. Este estudo foi realizado ao sul do Estado do Amazonas, em área com terra preta arqueológica (TPA), floresta, pastagem, agrofloresta e cana-de-açúcar. Nessas áreas, foram estabelecidas malhas de 70 × 70 m, com espaçamento regular de 10 m, totalizando 64 pontos em cada ambiente. Os solos foram coletados na profundidade de 0,0-0,10 m. Foram determinados os atributos químicos (pH em água, MO, P, K, Ca, Mg, H+Al, SB, CTC e V). Os dados foram analisados utilizando-se técnicas de estatística descritiva e geoestatística. Grande parte dos atributos estudados apresentou estrutura de dependência espacial. O modelo esférico foi o que melhor se ajustou aos atributos químicos nos diferentes ambientes, onde somente a cana-de-açúcar evidenciou melhor ajuste ao modelo exponencial. As áreas de TPA e cana-de-açúcar mostraram maior heterogeneidade dos atributos químicos do solo, apresentando menor alcance e maior densidade amostral, e a área com floresta e agrofloresta apresentaram menor variabilidade dos atributos químicos.

The lack of information concerning the variability of soil properties has been a major concern of researchers in the Amazon region. Thus, the aim of this study was to evaluate the spatial variability of soil chemical properties and determine minimal sampling density to characterize the variability of these properties in five environments located in the south of the State of Amazonas, Brazil. The five environments were archaeological dark earth (ADE), forest, pasture land, agroforestry operation, and sugarcane crop. Regular 70 × 70 m mesh grids were set up in these areas, with 64 sample points spaced at 10 m distance. Soil samples were collected at the 0.0-0.1 m depth. The chemical properties of pH in water, OM, P, K, Ca, Mg, H+Al, SB, CEC, and V were determined at these points. Data were analyzed by descriptive and geostatistical analyses. A large part of the data analyzed showed spatial dependence. Chemical properties were best fitted to the spherical model in almost all the environments evaluated, except for the sugarcane field with a better fit to the exponential model. ADE and sugarcane areas had greater heterogeneity of soil chemical properties, showing a greater range and higher sampling density; however, forest and agroforestry areas had less variability of chemical properties.

A carência de informações referentes a levantamento de solos na região sul do Amazonas é muito grande. O uso de ferramentas, como a geoestatística, pode auxiliar no melhor planejamento, uso e manejo desses ambientes. Neste trabalho, objetivou-se utilizar semivariogramas escalonados no planejamento amostral de atributos físicos do solo em ambientes na região Sul do Amazonas. Foram selecionadas cinco áreas, localizadas ao sul do Estado do Amazonas, com diferentes usos: floresta, terra preta arqueológica (TPA), pastagem, cana-de-açúcar e agrofloresta. Nessas áreas, foram estabelecidas malhas regulares contendo 64 pontos espaçados de 10 m entre si. Determinaram-se composição granulométrica, resistência do solo à penetração, umidade, densidade do solo e das partículas, macro e microporosidade, porosidade total e estabilidade dos agregados em água, nas profundidades de 0,0-0,20 m. Foram realizadas análises estatísticas descritivas e geoestatística. O ambiente que necessitou de menor densidade amostral foi o de pastagem e o que demonstrou a necessidade de maior densidade amostral foi o de floresta. Concluiu-se que os ambientes manejados evidenciaram diferenças nos seus atributos físicos em relação à área de floresta, com destaque a área com TPA que se apresentou melhor fisicamente em relação aos demais. Os atributos físicos avaliados apresentaram estrutura de dependência espacial com pequena variação na sua variabilidade da floresta para os demais ambientes, e o uso do parâmetro alcance do semivariograma se evidenciou eficiente para determinar a densidade amostral ideal.

There is a great lack of information from soil surveys in the southern part of the State of Amazonas, Brazil. The use of tools such as geostatistics may improve environmental planning, use and management. In this study, we aimed to use scaled semivariograms in sample design of soil physical properties of some environments in Amazonas. We selected five areas located in the south of the state of Amazonas, Brazil, with varied soil uses, such as forest, archaeological dark earth (ADE), pasture, sugarcane cropping, and agroforestry. Regular mesh grids were set up in these areas with 64 sample points spaced at 10 m from each other. At these points, we determined the particle size composition, soil resistance to penetration, moisture, soil bulk density and particle density, macroporosity, microporosity, total porosity, and aggregate stability in water at a depth of 0.00-0.20 m. Descriptive and geostatistical analyses were performed. The sample density requirements were lower in the pasture area but higher in the forest. We concluded that managed-environments had differences in their soil physical properties compared to the natural forest; notably, the soil in the ADE environment is physically improved in relation to the others. The physical properties evaluated showed a structure of spatial dependence with a slight variability of the forest compared to the others. The use of the range parameter of the semivariogram analysis proved to be effective in determining an ideal sample density.

O objetivo deste trabalho foi avaliar o desempenho da simulação sequencial gaussiana (SSG) e da simulação sequencial indicatriz (SSI) na modelagem da incerteza das predições do K disponível em área de cana-de-açúcar, e comparar as simulações com o método já consagrado de krigagem ordinária (KO). Uma malha amostral com 626 pontos foi instalada em área de 200 ha, no Município de Tabapuã, em São Paulo. As simulações reproduziram a variabilidade dos dados amostrais de K disponível, enquanto a KO superestimou os baixos teores de K e subestimou os altos. O mapa de desvio-padrão obtido a partir da KO mostrou menor variação ao longo da área de estudo, quando comparado aos mapas obtidos a partir das simulações. A SSI obteve acurácia 22% superior à obtida pela SSG, na modelagem da função de distribuição condicional do K. As simulações apresentam maior eficiência que a KO para modelar incerteza na distribuição espacial do K. A SSI apresenta melhor desempenho que a SSG na estimativa dos teores de K disponível, em área de cana-de-açúcar.

The objective of this work was to evaluate the performance of the sequential Gaussian simulation (SGS) and the sequential indicator simulation (SIS) for modeling the uncertainty of available K predictions in a sugarcane area, and to compare both simulations to the already established method of ordinary kriging (OK). A sampling grid with 626 points was installed in an area of 200 ha, in the municipality of Tabapuã, in the state of São Paulo, Brazil. The simulations reproduced the variability in the available K sample data, whereas OK overestimated the low K levels and underestimated the high ones. The standard deviation map obtained from OK showed less variation along the studied area when compared to the maps obtained from the simulations. SIS achieved an accuracy 22% higher than that obtained by SGS for modeling the conditional distribution function of K. The simulations have higher efficiency than OK for modeling the uncertainty in the spatial distribution of K. SIS has better performance than SGS for estimating the levels of available K in sugarcane area.

O objetivo deste trabalho foi estimar o coeficiente de erodibilidade em sulcos e entressulcos, por meio de parâmetros da cor do solo. Foram selecionadas três áreas cultivadas com soja, em Argissolos Amarelos coesos do Leste Maranhense. Em cada área, foram retiradas 121 amostras na profundidade de 0,00-0,20 m. Foram determinados os valores de espectroscopia de reflectância difusa na faixa do visível, para obtenção dos valores de matiz, valor e croma. A partir destes constituintes da cor, foi calculado o índice de avermelhamento para cada amostra. Foram desenvolvidos modelos para avaliar o efeito de cada componente da cor sobre a erodibilidade em sulcos e entressulcos. Esses componentes apresentaram R2 que variou de 0,37 a 0,70. Os modelos gerados obtiveram R2 de 0,70 e 0,73, para entressulcos e sulcos, respectivamente. A cor do solo determinada por espectroscopia de reflectância difusa pode ser utilizada como método alternativo para estimar o coeficiente de erodibilidade de Argissolos Amarelos coesos.

The objective of this work was to estimate the rill and interrill erodibility coefficient through soil color parameters. Three areas were selected, which were cultivated with soybean in cohesive Ultisols of the eastern region of the state of Maranhão, Brazil. In each area, 121 samples were collected at a depth of 0.00-0.20 m. The values of diffuse reflectance spectroscopy in the visible range were determined, in order to obtain the values of hue, value, and chroma. From these color constituents, the redness index was calculated for each sample. Models were developed to evaluate the effect of each color component on rill and interril erodibility. These components showed R2 ranging from 0.37 to 0.70. The generated models obtained R2 of 0.70 and 0.73 for interill and rill, respectively. Soil color determined by diffuse reflectance spectroscopy can be used as an alternative method to estimate the erodibility coefficient of cohesive Ultisols.

A demanda nacional e internacional por mapas de atributos do solo tem aumentado. Os objetivos deste trabalho foram caracterizar e associar a variabilidade da granulometria, os atributos químicos e a cor de solos coesos a diferentes formas de paisagem, em áreas agrícolas e de vegetação nativa, por meio de técnicas geoestatísticas. Para a instalação do experimento, foram escolhidas três áreas representadas por uma área cultivada com soja e, contígua a essa, uma com cobertura vegetal remanescente de três feições de cerrado, designadas de Cerradão (A), Cerrado (B) e Campo Cerrado (C). As áreas A e B estão localizadas em pedoforma côncava e a área C, na convexa. Em cada área, foram estabelecidas malhas de amostragem com 121 pontos; nas áreas com cobertura vegetal construíram-se transeções com cinco pontos espaçados em 20 m. Os maiores alcances médios, considerando ambas as profundidades avaliadas, foram encontrados para a área A, sendo de 115 m para granulometria, 157 m para atributos químicos e 168 m para a cor do solo. A área B apresentou alcances médios de 95, 64 e 160 m para granulometria, atributos químicos e cor do solo, respectivamente. A área C, por sua vez, exibiu alcances médios de 63, 65 e 58 m para granulometria, atributos químicos e cor do solo, respectivamente. O ambiente com maior variabilidade (área C) está relacionado com locais de ocorrência de vegetação do tipo Campo Cerrado e pedoforma convexa. Esse mesmo local evidenciou a menor capacidade de resposta ao manejo da cultura de soja, evidenciado pelos índices de fertilidade do solo para essa cultura, com destaque para os baixos valores de matéria orgânica (9,20 mg kg-1) e CTC (29,60 mmol c dm-3). Assim, pode-se afirmar que para o compartimento geológico estudado, os ambientes de alta variabilidade sempre estão associados a áreas com menor resposta ao manejo do solo para a cultura da soja.

The national and international demand for maps of soil properties has increased. The aim of this study was to characterize cohesive soils and associate their variability of particle size, chemical properties, and color to different landforms in agricultural areas and native vegetation using geostatistical techniques. To set up the experiment, we selected three areas of soil consisting of an area planted to soybeans and, contiguous to it, another area with plant cover remaining from three types of cerrado (tropical savanna), designated Cerradão (A), Cerrado (B), and Campo Cerrado (C). The areas A and B are located on a concave landform, while area C is on a convex landform. Sampling grids with 121 points were established in each area, and in areas with native vegetation, transects were constructed with five points spaced at 20 m. The largest mean ranges, considering both depths evaluated, were found for area A, with 115 m for particle size, 157 m for chemical attributes, and 168 m for soil color. Area B had mean ranges of 95, 64, and 160 m for grain size, chemical attribute, and soil color, respectively. For its part, area C exhibited the mean ranges of 63, 65, and 58 m in grain size, chemical attributes, and soil color, respectively. The environment with the greatest variability (area C) is related to locations with the occurrence of Campo Cerrado vegetation and a convex landform. This same site had the lowest responsiveness to soybean crop management, shown by soil fertility indicators for this crop, especially the low values for organic matter (9.20 mg kg-1) and CEC (29.60 mmol c dm-3). Thus, it can be stated that for the geological compartment studied, the environments of high variability will always be associated with areas with lower response to soil management for soybean.