This study aimed to evaluate enzyme activity, glomalin-related soil proteins (GRSP), soil chemical attributes, and total organic carbon (TOC) in two Agroforestry systems (AFS) (AFS-1 and AFS-2), in a traditional agriculture area (TA), and secondary forest (SF) area in Paraty (RJ). Soil samples (from 0 to 5 cm depth) were collected during the rainy and dry seasons. AFS improves and/or maintains soil chemical indicators based on pH increase, reduces aluminum saturation and maintains soil nutrient content (Ca, Mg and K), when compared with SF. The contribution of organic material and the biodiversity of the AFS provide the maintenance of the total organic carbon content of the soil. AFS maintain the activity of the enzymes protease, β-glucosidase, acid phosphatase, and total enzyme activity (FDA), and the production of glomalin-related soil protein at levels similar to those observed in SF, especially during the rainy season.
Studies on spatial variability of soil attributes of tropical pastures gather information that can assist in decision making about managements of these soils. The objective of the present study was to evaluate the spatial variability of soil chemical attributes and their effects on grass yield of Tifton 85. The experiment was carried out in an area of 3.91 ha at the Feno Rio Farm of the Federal Rural University of Rio de Janeiro, Seropédica, RJ, Brazil. Soils of the 0-0.20 and 0.20-0.40 m layers were sampled considering an irregular sampling mesh, making a total of 50 georeferenced points. The parameters evaluated were: the soil chemical attributes pH, Al+3, Ca+2, Mg+2, Na+, K+, P, H+Al, and total organic carbon (TOC); and the Tifton 85 dry matter yield (DMY). The results of these parameters were subjected to descriptive statistics, linear correlation, and geostatistics, and maps were developed for the analyses. Regions with grass yields different from the general mean were found in the area, which presented mean grass yield of 2248 kg ha-1. The soil chemical parameters Na+, Ca+2, TOC, and H+Al were significantly correlated with DMY, confirming that they are important and affect the Tifton 85 grass yield. The mapping of the Tifton 85 cycle is important for understanding the variability of DMY. The investigation of areas with different productive potentials should be followed by development of maps of soil chemical attributes to correlate and understand the ratios that may be involved with these variations.
Soil is a fundamental natural resource for subsistence and development of humanity, exploited mainly for agriculture. Agricultural practices, though, are improperly performed, compromising edaphic conditions and favoring erosive processes, which mainly culminate in the loss of soil and nutrients. Water erosion represents the main form of soil degradation, given that the impact of raindrops on the soil results in the detachment of particles, a process favored by factors such as climate, relief, soil vegetation and use and occupation. The objective of the study was to classify four gullies based on their evolutionary turns and to judge the physical-chemical classifications of the soil at the internal and external faces of the gullies. The morphology of the gullies was classified by aerial images generated by drones. The gullies were mapped using Google Earth images from 2016. The qualitative assessment was performed using the digital field-elevation curvature (MDESC) model with field validation. Deformed samples were collected at depths of 0-10 and 10-20 cm, while non-deformed samples were collected at depths of 0.0-0.10 cm to evaluate their chemical and physical attributes. A nonparametric 5% Kruskal-Wallis statistical analysis was performed on the resulting data. The chemical and physical attributes of the soil differed according to the evolutionary stage of the surfaces (internal and external) at depths of 0 to 10 cm, while the faces showed differences in depth of 10 to 20 cm.
VARIABILIDADE DE ATRIBUTOS EDÁFICOS EM DIFERENTES AMBIENTES DE VOÇOROCAS NO BIOMA DA MATA ATLÂNTICA JOÃO HENRIQUE GAIA GOMES1, MARCOS GERVASIO PEREIRA1, MARCOS BACIS CEDDIA1, ANDRÉ GERALDO DE LIMA MORAIS1, FABIANA DA COSTA BARROS2 1 Departamento de Solos, Universidade Federal Rural do Rio de Janeiro, Km 07, Zona Rural, BR-465, 23890-000, Seropédica, Rio de Janeiro, Brasil, gaia.gomes.pgeaamb@gmail.com; mgervasiopereira01@gmail.com; marcosceddia@gmail.com; andrehmuz@hotmail.com. 2 Departamento de Engenharia Agrícola e Ambiental, Universidade Federal Fluminense, R. Mario Santos Braga, 30 - Centro, 24020-140, Niterói - RJ, Rio de Janeiro, Brasil, barros.faby@hotmail.com. RESUMO: O estudo teve como objetivo avaliar e determinar a variabilidade espacial de atributos químicos e físicos do solo no ambiente interno e externo de voçoroca em pedoforma convexa. O estudo foi realizado na sub-bacia do ribeirão do Cachimbal, Pinheiral, RJ. O mapeamento da área foi desenvolvido a partir da imagem do ano de 2017, obtida no Google Earth, com resolução espacial de 2,34 metros, sendo realizadas avaliações quantitativas, quanto a expressão de voçorocas e qualitativas (pedoforma côncava ou convexa) através do modelo digital de elevação de superfície de curvatura (MDESC), com validação no campo. Posteriormente, foi selecionada uma voçoroca ocorrente em pedoforma convexa, mais expressiva, em que foram coletadas amostras nos ambientes interno e externo na profundidade de 0,0-0,10 m para avaliação dos atributos químicos e físicos das voçorocas. Verificou-se que algumas variáveis necessitam de um número amostral maior e/ou que sejam testados outros métodos geoestatísticos, pois não foi possível verificar a existência de dependência espacial. Foi observado que os atributos químicos e físicos do solo apresentam variabilidade espacial de forma diferenciada quando comparados os ambientes interno e externo. A geoestatística apresenta-se com elevado potencial na espacialização dos atributos químicos e físicos do solo em ambientes degradados como voçorocas. Palavras-chave: erosão, geoestatística, indicadores de qualidade do solo. VARIABILITY OF SOIL ATTRIBUTES IN DIFFERENT GULLIE ENVIRONMENTS IN ATLANTIC FOREST BIOME ABSTRACT: The study had to evaluate and determine the spatial variability of soil chemical and physical attributes in the internal and external environment of a gullie convex pedoform. The study was conducted in the Cachimbal stream sub-basin, Pinheiral, RJ. The mapping of the area was developed from the image of 2017, obtained in Google Earth, with a spatial resolution of 2.34 meters, being quantitative data quantities, with a voice expression and quality (concave or convex pedoform) through digital curvature surface access model (CSEDM) with field validation. Subsequently, it was an incident intermittence, was more intense, in which samples were collected indoors and outdoors at a depth of 0-0.10 m for the evaluation of chemical and physical attributes of gullies. The tests were larger than a larger number and / or larger than the most recent geological tests since it was impossible to verify the existence of spatial dependence. It was seen that the chemical and physical attributes of soil spatial variability differed compared to indoor and outdoor environments. A geostatistic can spatialize the chemical and physical attributes of the soil in degraded environments such as gullies. Keywords: erosion, geostatistics, soil quality indicators.
Water erosion acts as the main form of soil degradation, promoting the release of particles that associated with factors such as climate, relief, soil vegetation and use and occupation favor this process. This study aimed to evaluate whether gullies are more likely to be present in a specific type of landform and how physical and chemical soil characteristics vary between the internal and external environments of concave and convex gullies. The study was performed in the Cachimbal River sub-basin, Pinheiral (RJ). Gullies were mapped and the quantitative and qualitative evaluations (occurrence in concave or convex surface). For each type of landform, one gully was selected. Soil samples (disturbed and undisturbed) were collected from the internal and external surfaces of each gully at a depth of 0-10 cm and soil chemical and physical characteristics were determined. More gullies were present in convex landforms and differences in soil characteristics were observed between the internal and external gully surfaces, but not between different landforms. Ca+2, S value, H+Al, T value, Mg+2, TOC and K+ were associated with the external surface, and P, Al+3, aluminum saturation, V%, and pH with the internal surface. Natural and total clay content, and soil and particle density were the physical characteristics associated with the external surface, and total and fine sand content, porosity, degree of flocculation, and silt content with the internal surface.
Reminiscências da infância viada:Reflexões sobre o controle escolar da (homos)sexualidade João Gomes Junior 1Resumo: A proposta deste artigo é ser uma auto etnografia, uma reconstrução das reminiscências da minha "infância viada" como meio de compreender o controle escolar sobre a (homos)sexualidade. Objetivo neste texto, dessa forma, apresentar em um primeiro momento um panorama histórico sobre a normatização da sexualidade infantil e a escola como espaço de controle da mesma no Brasil de acordo com parte dos resultados da minha pesquisa de mestrado em História, e em seguida fazer uma crítica, a partir da minha experiência pessoal quando criança, das forças que atuam de forma excludente, colonizadora e subalternizadora nos colégios.Palavras-chave: Auto etnografia; Infância viada; História da educação; Descolonialismo. Reminiscences of viable childhood:Reflections on school control of (homos) sexuality
The use of Precision Agriculture tools and soil attributes has contributed to local agricultural management in the identification of different productive potentials and quality of pastures. The present study aimed to use Precision Agriculture tools to investigate the spatial variability of soil organic matter fractions and soil chemical and physical attributes and to delineate management zones in pasture soils cultivated under tropical conditions. The study was conducted on a hay production farm located in Seropédica, Brazil. Fifty points were collected on a irregular grid and soil samples were taken at depths of 0-0.20 and 0.20-0.40 m and crop productivity was evaluated. Chemical and physical soil organic matter fractionation was performed to obtain data on fulvic acid, humic and humin fractions, mineral-associated and particulate organic carbon, and light organic matter. Geostatistics and multivariate analysis (principal component analysis and k-means clustering) were performed to define the management zones. The results obtained contributed to the division of the pasture area into two regions that can be managed in different ways aiming to increase soil organic matter in a localized manner with the possibility of reducing the use of inputs and directed management that respects the productive potential of the pasture on the farm.
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