Determination of mineralizable carbon (C) is based on the evolution of C-CO2, reflecting the activity of soil biota in soil organic matter (SOM) decomposition, and can be used as a testing parameter in agroecological production systems. The objective of the present work was to quantify mineralizable C in aggregates of different biogenic and physiogenic formation pathways in agroecological management systems in the city of Seropédica, state of Rio de Janeiro. Five sampling areas were selected: (1) 10-year agroforestry system (AFS), (2) 15-year full sun coffee (C-SUN), (3) 15-year shaded coffee (C-SHA), (4) 10-year phlegm alleles (FLE), and (5) 6-year no-till planting system with corn and eggplant (NT) in Red-Yellow Argissolo in Seropédica-RJ.Morphological patterns were used to identify the formation pathway (biogenic and physiogenic) of aggregates. In these, fertility, total organic carbon (TOC), and total nitrogen (TN) were evaluated. The evolution and accumulation of C-CO2were determined in the laboratory after 35 days of incubation. The NT area under agroecological management present higher C-CO2 accumulation between the systems with biogenic aggregates and less accumulation in the physiogenic aggregates.
The objective of this study was to evaluate the bulk density, total pore volume, carbon stock and natural abundance of 13C in Rhodic Ferralsol in no-tillage system (NTS) areas under different succession and rotation of cultures in the Cerrado of Goiás State, Brazil. In order to do so, NTS areas were selected in Montividiu, Goiás, under the same soil and climatic conditions as the following rotations: soybean-corn succession, soybean-millet succession, soybean-corn-millet-beans-cotton rotation, soybean-corn-brachiaria succession and a pasture area (PA), used as a control. In each area, samples were collected at depths of 0.0–0.05, 0.05–0.10, 0.10–0.20, and 0.20–0.40 m. The lowest levels of carbon content and stocks were verified in PA in comparison to the other areas evaluated. The NTS with soybean-corn-millet-beans-cotton crop rotation followed by NTS with soybean-corn-brachiaria succession were those that presented greater potential for carbon stock increase and total soil pore volume, as well as bulk density reduction. The origin of the soil organic matter in the NTS areas is related to plants employing the C4 photosynthetic cycle; however, for mixed C3 and C4 plant systems, the isotopic signature of 13C is reduced, mainly in areas with crop rotation.
Determining the real water requirement for pastures is essential for the rational use of irrigation. The aim of this work was to assess the crop coefficient and performance of the Thornthwaite and Mather soil water balance (ThM) adapted to estimate the daily actual evapotranspiration (ETa) of a pasture in relation to the Bowen ratio - energy balance method (BREB). The experiment was carried out from July 2018 to June 2019 in Cachoeiras de Macacu, Rio de Janeiro State (RJ) (22º 27’S; 42º 45’W and 30 m altitude). Micrometeorological and meteorological measurements were conducted in a micrometeorological tower installed in the pasture and also in an automatic weather station, located 1 km from the pasture area. The ThM model was evaluated using linear regression between ETa determinate from BREB and the estimates from ThM using its coefficient of determination (R²) and the modified Willmott agreement index (dm). The ThM model underestimated (between 11 and 16%) the ETa for all seasons, except for spring, which overestimated by 1%. The highest precision and accuracy of the estimates were observed in autumn (R² = 0.84 and dm = 0.68) and spring (R² = 0.83 and dm = 0.82). In summer (R² = 0.56 and dm = 0.73) and winter (R² = 0.43 and dm = 0.66), the lower performance was caused by the inability of the model to represent water extraction from the soil in dry periods.
Records of changes in the phytosociological structure of vegetation can be observed more clearly in soils that have more significant accumulation of organic matter, like those occurring in high-mountain environments. The aim of this study was to characterize soils formed in high-mountain environments in the Itatiaia National Park (INP), state of Rio de Janeiro, southeastern Brazil, and to discuss the potential of preserved phytoliths as markers of vegetative history and environmental factors. Four profiles were selected, which were morphologically described and evaluated for their physical and chemical properties. For phytolith analysis and high-resolution determination of the stable carbon isotopes, samples were collected at 0.10 m intervals. The profiles showed highly similar morphological characteristics, with peat deposits and colluvial sediments as source material, produced in the highest parts of the landscape. High-mountain soils in the INP have properties related to high contents of organic matter, like high acidity, low base saturation, and high CEC values due to high H + contents. The soils are formed by the addition of plant residues, which accumulate due to the cold and humid climate during most of the year in these environments. The phytolith assemblage had a high frequency of morphotypes characteristic of temperate, cold, and high elevation intertropical regions, especially of Pooideae plants. The phytolith indexes indicated open vegetation environments with a predominance of C 3 grasses, suggesting cold climate conditions, and corroborating the δ 13 C isotopic values. The results of phytolith analysis of the profiles reflected characteristics related to soil genesis. Organism is the main soil formation factor, conditioned by the factors relief (elevation) and climate, which resulted in low temperatures and lead organic matter accumulation.
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.
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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, firstname.lastname@example.org; email@example.com; firstname.lastname@example.org; email@example.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, firstname.lastname@example.org. 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.
The partial or total use of organic compounds for forest seedling production has been considered a reliable alternative to commercial substrate. The objective of this study was to investigate the red-angico (Anadenanthera macrocarpa) and pink kapok (Chorisia speciosa) seedlings development performance cultivated with different proportion of commercial substrate mixed with vermicompost or sewage sludge. Seedlings were produced under greenhouse conditions and different commercial substrate mixed proportions with vermicompost and sewage sludge at 0 (only commercial substrate), 25, 50, 75, and 100% (only organic compound) were evaluated. An increment of plant height and steam diameter for red-angico and pink kapok were observed when both vermicompost or sewage sludge were added to the substrate. Best seedlings development results were found when organic compound represented from 50-75% of the substrate. The use of vermicompost and sewage sludge have showed a good alternative to the commercial substrate.
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