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O aumento na produção de resíduos sólidos e disposição inadequada destes resíduos em lixões representa um dos principais problemas relacionados a fatores ambientais que ocorre em diversos municípios brasileiros, causando a contaminação do solo decorrente desse aumento. Nesse sentido, o objetivo deste trabalho foi quantificar os atributos físicos e químicos do solo em uma área do lixão, na cidade de Humaitá (AM). Foram escolhidos seis perfis de forma aleatória no entorno de toda a área do lixão, em seguida foram coletadas amostras de solos nos períodos seco e chuvoso do ano (2018), nas camadas de 0,00-0,10; 0,10-0,20; 0,20-0,30; 0,30-0,40; 0,40-0,50 m, totalizando 30 amostras no final de cada período (seco e chuvoso). Em seguida, foram realizadas análises físicas: textura, densidade, macroporosidade, microporosidade, volume total de poros, umidade e resistência do solo a penetração; e químicas: pH em água, alumínio trocável, acidez potencial, carbono orgânico, estoque de carbono, fósforo e potássio disponível. A produção de compostos orgânicos tende a ser maior no período seco, logo uma atenção a ações que visem a mitigação desse fenômeno deve ser dada visando menor impacto ambiental no solo e prevenindo que alcance lençóis freáticos por meio de lixiviação durante o período chuvoso, considerando o intenso regime hídrico no Estado do Amazonas.

The Mehlich-1 extractor is the most used in Brazil, however it extracts low phosphorus (P) levels in soils with high clay levels and iron-bound (Fe) and aluminum (Al) fractions. Thus, we aimed to evaluate the P availability and fertility classes in Yellow Latosol (YL) and Gleysol Haplicum (GH) soils using Mehlich-1, Mehlich-3 and anion exchange resin extractors, as well as to estimate the critical P levels in the soil and in plants for establishing Urochloa humidicola cv. Common. All extractors were efficient in evaluating the availability of P in the soil, however the anion exchange resin showed a high correlation with the P accumulation in the shoot, which can be considered the most efficient method in P extraction. However, we recommend the Mehlich-3 extractor due to its high efficiency in extracting the P linked to the Fe and Al fractions, in addition to being a multi-element extractor. The critical level of P in the soil for establishing U. humidicola by Mehlich-3 in YL is 10.32 mg dm-3, while it is 7.46 mg dm-3 in GH. The critical P level in plants grown in YL is 1.20 mg dm-3, and it is 1.54 mg dm-3 in GH. The estimated phosphate doses can be recommended for cultivating U. humidicola and can serve as a reference for future research on correlating and calibrating P doses.

Made available in DSpace on 2022-04-29T08:32:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-04-01 Changes in primary cover for agricultural crops in Amazonas region influence the phenomenon of spatial variability in soil properties. This phenomenon is still studied assuming that the spatial data is isotropic, but does not consider the anisotropic pattern of soil properties. Thus, the aim of this work was to characterize, identify and correct isotropic patterns of magnetic susceptibility (MS) measurements using anisotropic models that actually represent the spatial aspects of the data. Three cultivation areas and one under native forest, classified as Haplic Alisol, were georeferenced and sampled by a mesh system covering 192 samples per area. Texture, X-ray diffraction and frequency-dependent (χfd) and mass-specific (χlf and χhf) magnetic susceptibility analyzes were performed. Then, classical and geostatistical analyzes were applied to the data, assuming isotropy and anisotropy. All χ frequencies were shown to be spatially dependent, satisfying the isotropy hypothesis. Thereby, the application of anisotropic analysis was able to confirm the presence of all types of anisotropy in Alisols. Anisotropic correction provided an improvement in models that fit the directional trends within the areas, and provided a reduction in the nugget effect and an increase in the correlation ranges. Thus, the generated kriging maps improved the patches of zonal trends of greater or lesser χ that stand out at the level of sub-regions. These zones should, therefore, be used as indicators of variability, paying special attention during their management, especially in research related to the delimitation of specific management zones. Amazon Environment and Soil Research Group (GPSAA) Federal University of Amazonas (UFAM), Amazonas Amazon Environment and Soil Research Group (GPSAA) Center of Agricultural Sciences Federal University of Paraíba (CCA/UFPB), Paraíba Department of Agronomy Federal University of Roraima (UFRR), Roraima Soil Characterization for Specific Management Research Group (CSME) Faculty of Agrarian and Veterinary Sciences Paulista State University (FCAV/UNESP), São Paulo Department of Soils and Rural Engineering Agricultural Sciences Center Federal University of Paraíba (DSER/CCA/UFPB), Paraíba Federal Institute of Rondônia (IFRO), Rondônia Soil Characterization for Specific Management Research Group (CSME) Faculty of Agrarian and Veterinary Sciences Paulista State University (FCAV/UNESP), São Paulo

In the Amazon region, soil patches with an anthropic A horizon are found, called Indian black earths (IBEs). Indian black earths are highly fertile and, therefore, are deforested by small local farmers to cultivate without basic management that maintains soil and crop sustainability. Therefore, in order to evaluate the effect of using different cultures on the spatial variability of soil chemical attributes, three cultivated IBEs and one IBE under natural forest were selected for georeferencing and sample collection. The collection was made with a mesh system with 88 points per IBE, stratified in three layers: 0–0.05, 0.05–0.10 and 0.10–0.20 m. The soil was sampled, dried in the shade and sieved to obtain the fine earth fraction for analysis of chemical attributes. Descriptive statistical and geostatistical analyses were applied to the results. The use and management of soil influenced the spatial behavior of the chemical attributes of IBEs. The cultivation of Brachiaria over many years favored the reduction of the spatial variability of chemical attributes. The use of cacao and coffee crops also favored the homogeneity of the IBEs in relation to the natural forest, but not as much as for Brachiaria, likely due to the succession of crops that preceded these crops. The IBE in the forest contains a high natural spatial correlation in the first 0.1 m of the surface; however, more than 70% of this correlation is linked to a random variation.

Studies related to the monitoring of soil quality by physical attributes are important for the evaluation and maintenance of the sustainability of agricultural systems, besides indicating the appropriate management of the environment, aiming at its conservation and productivity.The objective of this study was to evaluate the stability of aggregates and organic carbon after the application of gypsum, soil scarification and a succession of crops.The treatments consisted of an absence and addition ofgypsum, absence and presence of soil scarification, and three systems of crops in succession.The experimental design was made of randomized blocks, in a 2x2x4 factorial scheme, with eightreplications.The aggregates were evaluated as stabled in water and soil organic carbon content. The treatment where gypsum was applied, as well as the soybean/maize/brachiaria/fallow (SMBF) succession system, presented better results in soil aggregation and higher levels of organic carbon. Estudos relativos ao monitoramento da qualidade do solo pelos atributos físicos são importantes para a avaliação e manutenção da sustentabilidade dos sistemas agrícolas, além de sinalizar o manejo adequado do ambiente, visando à sua conservação e produtividade. Este trabalho teve por objetivo avaliar a estabilidade de agregados e teor de carbono orgânico, após a aplicação de gesso, escarificação do solo e sucessão de culturas. Os tratamentos consistiram na ausência e adição de gesso agrícola, ausência e presença de escarificação do solo, e três sistemas de sucessão de culturas. O delineamento experimental foi em blocos casualizados, em esquema fatorial 2x2x3 com oito repetições. Sendo avaliada a estabilidade dos agregados estáveis em água e teor de carbono orgânico do solo. O tratamento onde foi aplicado gesso agrícola e o sistema de sucessão SMBP apresentaram melhores resultados na agregação do solo e maiores teores de carbono orgânico.

Indian Black Earths (IBEs) are distributed throughout the Amazon. They are characterized by their high chemical fertility and agricultural potential. IBEs have high organic carbon, favouring the improvement of soil structure. This work aimed to evaluate the aggregates and organic carbon (OC) spatial variability in different IBEs in southern Amazonas. We evaluated the organic carbon spatial variability, mean weight diameter (MWD), soil bulk density (ρb) and aggregate classes under three uses of soil: pasture, cocoa, and coffee. We collected 528 soil samples in a point grid according to its use at two depths: 0.0-0.05 m and 0.10-0.20 m. Results were subjected to variance, descriptive, and geostatistical analyses. We concluded that the soil use influenced the IBEs physical attributes soil behavior, concentrating the higher values of CO, aggregates > 2.00 mm, and MWD at 0.0-0.05 m in relation to ρb and aggregates < 2.00 mm where the higher values were the ones at 0.10-0.20 m. Aggregates< 2.00 mm (0.10-0.20 m) and OC (0.0-0.05 m) did not show spatial dependence, while the class of aggregates > 2.00 mm was the only attribute which represented to be a natural characteristic of the soil, with a strong spatial dependence, independently the land use and depth. There was no spatial relationship between the attributes studied and the geomorphic diversity. As Terras Pretas de Índio (TPIs) encontram-se distribuídas por toda a Amazônia. Elas são caracterizadas pela alta fertilidade química e potencial agrícola. As TPIs possuem alto carbono orgânico, favorecendo a melhoria da estrutura do solo. Este trabalho teve como objetivo avaliar a variabilidade espacial dos agregados e do carbono orgânico (CO) em diferentes usos de TPIs no sul do Amazonas. Foi avaliado a variabilidade espacial do carbono orgânico, diâmetro médio ponderado (DMP), densidade do solo (ρb) e as classes de agregados sob três usos do solo: pastagem, cacau e café. Nas áreas estudas construiu-se um grid regular de pontos, de acordo com o uso do solo e nas profundidades, 0-0,05 m e 0,10-0,20 m, totalizando 528 amostras de solo. Os resultados foram submetidos à análise de variância, descritiva e geoestatística. O uso do solo influenciou o comportamento dos atributos físicos das TPIs, concentrando os valores mais altos de CO, agregados > 2.00 mm e DMP na profundidade 0,0-0.05 m em relação a ρb e agregados 2,00 mm foi o único atributo que representou uma característica natural do solo, com forte dependência espacial, independentemente do uso e profundidade do solo. Não houve relação espacial entre os atributos estudados e a diversidade geomórfica.

Having in mind the importance of knowing the variability and spatial correlation of soil properties in Indian Dark Earth (IDE), we evaluated in this study the variability and the spatial correlation of aggregates and carbon in an Ultisol under coffee cultivation in southern Amazonas. It was established a 48 x 88 m sampling grid spaced 06 x 08 m, totalling 88 sampling points. Then soil samples were collected at: 0.0-0.05, 0.05-0.10, and 0.10-0.20 m layers. The spatial variability of the Mean Weighted Diameter (MWD) attributes, aggregates > 2 mm, < 2 mm, bulk density (BD) and organic carbon (OC) was analyzed by adjusting the simple semivariograms, while spatial correlations of the OC with aggregates and BD were analyzed by cross-semivariogram. We could conclude that there was spatial dependence in the variables, wherein the largest ones were observed at 0.0-0.05 m, except for Mean Weighted Diameter (MWD) and aggregates greater than 2.00 mm with larger range of values in depth from 0.05-0.10 and 0.10-0.20 m. The mean weight diameter and aggregate class attributes greater than 2.00 mm had negative spatial correlation with organic carbon at 0.0-0.05 m, while the smaller aggregates than 2.00 mm classes and bulk density correlated positively with organic carbon at 0.0-0.05 m and 0.10-0.20 m. Considerando a importância do conhecimento da variabilidade e correlação espacial dos atributos do solo em Terra Preta de Índio (TPIs), avaliou-se neste trabalho a variabilidade e a correlação espacial de agregados e carbono em um Argissolo Amarelo eutrófico sob cultivo de café na região sul do Amazonas. Foi estabelecido um grid amostral com dimensões de 48 x 88 m e espaçamentos de 06 x 08 m, totalizando 88 pontos amostrais. Em seguida, foram coletadas amostras de solos nas profundidades: 0,0-0,05, 0,05-0,10, e 0,10-0,20 m. A variabilidade espacial dos atributos diâmetro médio ponderado (DMP), agregados > 2 mm, < 2 mm, densidade do solo (Ds) e carbono orgânico (CO) foi analisada ajustando os semivariogramas simples, enquanto as correlações espaciais do CO com agregados e Ds foram analisadas por semivariogramas cruzados. Concluiu-se que as variáveis apresentaram dependência espacial, e os maiores alcances são constatados na profundidade 0,0-0,05 m, exceto para DMP e agregados maiores que 2,00 mm com maioresvalores de alcance na profundidade 0,05-0,10 e 0,10-0,20 m. Os atributos diâmetro médio ponderado e classes de agregados maior que 2,00 mm apresentam correlação espacial negativa com carbono orgânico na profundidade 0,0-0,05 m, enquanto a classes de agregados menor que 2,00 mm e densidade do solo apresentam correlação positiva com carbono orgânico nas profundidades 0,0-0,05 m e 0,10-0,20 m.