No abstract

Vegetation cover may show diversity and composition patterns of the soil invertebrate community, as a function of litter quantity and quality in a specific habitat. The objective of this work was to characterize the distribution of edaphic fauna in different monocultures. The study was carried out at Chapada Grande farm in Regeneração, PI. Four monoculture areas were chosen: no-tillage soybean, eucalyptus, pasture, and a preserved native cerrado forest. Soil fauna was collected in a dry and wet period by pitfall traps containing 4% formaldehyde. The edaphic fauna was evaluated by the number of individuals per trap per day, average richness and richness, Shannon diversity index and Pielou uniformity index. Data were submitted to analysis of variance and multivariate Principal Component Analysis (PCA). The highest number of individuals per day trap and of average richness were registered in the pasture, eucalyptus and forest areas in both periods, while soybean showed lower values with predominance of Coleoptera and Formicidae groups. The pasture and forest areas showed of higher Shannon index values in the two evaluated seasons, probably due to higher contributions organic residues in the soil that favors the shelter, feeding and reproduction conditions. Regarding the Pielou index, the soybean system showed higher values in this variable. The Aranae, Coleoptera, Formicidae and Diptera groups predominated in the humid period, while Coleoptera and Formicidae predominated in the dry period. Systems that generate greater accumulation of residues harbor a greater diversity of invertebrates of the edaphic fauna. Seasonality had an effect on all variables analyzed and the wet period showed more expressive values.

RESUMO:Brazilian agriculture has been highlighted in Savanna areas due to significant gains in production and productivity in this biome. However, the production model with intensive use of machines for several years causes drastic changes in soil physical quality. This study aimed to investigate the influence of conventional management adoption time in a Yellow Oxissol on soil physical properties. Soil density, particle density, total porosity and soil resistance to penetration were assessed in areas under conventional management, in different usage times, in comparison to a native Savanna, which was used as control. The areas under conventional management contributed to increase the density and reduce the porosity, which was intensified with time of soil use. In the 6 years area, the porosity showed values below 0.50 m 3 m -3 in the two measured layers. Higher penetration resistance values were observed to areas with higher use of time from 0.15 m depth, reaching values above 3.0 and 2.0 MPa in soils with 6 and 3 years of use, respectively, which is ranked as high. The native vegetation and the newly deforested area have provided less resistance to penetration along the profile, with values falling into low and moderate classes. Different time periods since the implementation of soil management were differentiated by the physical properties of studied soils.

The reforestation with eucalyptus has increased significantly in the Brazilian Savanah and it can promote changes on soil biological properties, mainly soil fauna. Thus, the aim of this study was to evaluate the composition of soil fauna in areas with Eucalyptus plantations of different ages compared with native savanna. The study was conducted in Eucalytptus plantations aged one, two, three and four years and area with native forest was taken as reference. Soil fauna was collected in the dry and rainy season to evaluate the number of individuals from different taxonomic groups, richness, uniformity and diversity. The highest number of soil fauna was found in eucalyptus plantations with one year old at both seasons. However, the richness did not differ between seasons. In areas where with eucalyptus plantations with one and two years old showed 90% of individuals represented by Coleoptera and Formicidae, which contributed for decreasing in fauna uniformity. The implantation of Eucalyptus early reduced the diversity and uniformity of soil fauna; however, there was a recovery of this biological attribute after two years of reforestation.Additional keywords: native forest; seasonality; species diversity. ResumoO plantio de eucalipto tem aumentado significativamente em áreas anteriormente ocupadas por vegetação de Cerrados, e isto pode promover mudanças nos atributos biológicos do solo, principalmente sobre a fauna edáfica. Desta forma, o objetivo do trabalho foi avaliar a composição da fauna do solo em povoamentos de eucalipto do solo com diferentes idades, em comparação com remanescentes de vegetação de Cerrados. O estudo foi realizado em quatro povoamentos de eucalipto, com 1; 2; 3 e 4 anos, e uma mata nativa de Cerrado como referência. Foram feitas avaliações do número de indivíduos de grupos taxonômicos da fauna do solo, e de características ecológicas dos grupos dessa fauna, como riqueza, riqueza média, índice de diversidade e de uniformidade. As coletas da fauna do solo foram realizadas nas estações úmida e seca. O maior número de indivíduos da fauna edáfica foi encontrado no povoamento de indivíduos com 1 ano de idade. A riqueza de espécies não diferiu entre as estações de coleta nas áreas avaliadas. Nos povoamentos com 1 e 2 anos de idade, aproximadamente 90% do total de indivíduos foram representados por Coleoptera e Formicidae, o que contribuiu para diminuir a uniformidade. Eucaliptos com menor tempo de implantação mostraram menor diversidade e uniformidade da fauna edáfica, entretanto houve recuperação destes atributos após dois anos de implantação.Palavras-chave adicionais: diversidade de espécie; mata nativa; sazonalidade.

RESUMO -A matéria orgânica do solo (MOS) pode ser definida como todo material que contém carbono orgânico do solo (COS), incluindo os microrganismos, vivos e mortos, resíduos de plantas e animais parcialmente decompostos, produtos da sua decomposição e substâncias orgânicas microbiológicas e/ou quimicamente alteradas. O fracionamento físico da MOS é caracterizado pela sua avaliação de forma menos destrutível comparado com o fracionamento químico. É realizada através de alterações na proporção das frações lábeis, como o carbono da fração grosseira, carbono orgânico particulado (COP), bem como, as frações que estejam associadas aos minerais (COAM), as quais podem fornecer informações importantes sobre a sustentabilidade ambiental e sobre a qualidade do solo. Os resultados obtidos deste fracionamento, que consiste na separação das frações da MOS agrupadas em diferentes tamanhos de partícula, são mais diretamente relacionados com frações que realmente existem no solo. Uma das ferramentas para que a técnica de fracionamento físico da matéria orgânica seja efetuada é a sonicação. O sonicador opera através da vibração ultrassônica, onde ocorre a formação de bolhas microscópicas, pela cavitação, o suficiente para produzir pressão e energia para o rompimento de ligações responsáveis pela agregação das partículas. Neste processo ocorre uma máxima dispersão na superfície das partículas do solo, fendas e linhas de fraqueza, com uma mínima alteração da amostra. A energia liberada para essa dispersão promove o aumento da temperatura da solução com o aumento do tempo de sonicação. Neste experimento, o nível de energia de 522 W (J mL -1 ) foi a necessária para dispersar os compartimentos da matéria orgânica do solo com maior proporção de carbono (C) associada aos minerais (COAM), e também com menor proporção, associada à fração particulada (COP).Palavras-chave -Carbono orgânico do solo, frações lábeis, energia ultrassônica, estabilidade de agregados.Abstract -Soil organic matter (SOM) can be defined as any soil organic carbon (SOC) material, including living and dead micro-organisms, partially decomposed plant and animal waste, decomposition products and organic microbiological substances and / or chemically altered. The physical fractionation of SOM is characterized by its less destructible evaluation compared to the chemical fractionation. It is performed through changes in the proportion of labile fractions, such as coarse fraction carbon, particulate organic carbon (POC), as well as fractions that are associated with minerals (COAM), which can provide important information on environmental sustainability and soil quality. The results obtained from this fractionation consisting of the separation of the fractions of the MOS grouped in different particle sizes are more directly related to the fractions that exist in the soil. One of the techniques of physical fractionation of organic matter is sonication. This technique operates through ultrasonic vibration, where the formation of microscopic bubbles occurs, through cavitation...

Integrated agricultural production systems have the potential to increase organic matter content, which is reflected in the soil carbon (C) and nitrogen (N) concentrations. Here, we evaluated the C and N stocks and its compartments in a typical distro cohesive yellow Ultisol under the no-till (NT) and crop-livestock integration (CLI) systems, in eastern Maranhão. Five areas with different management strategies were evaluated, more specifically, one area was managed under the NT system in succession for 14 years (soybean/millet), three areas had different CLI system adoption histories (i.e., CLI was adopted 2, 4, or 8 years prior to sample collection); and finally, one area consisted of native Cerrado (savannah) vegetation. Soil samples were collected at depths of 0-0.10, 0.10-0.20, 0.20-0.30, and 0.30-0.50 m,to analyze the content and total stocks of carbon (C) and its compartments (physical and chemical), N content, soil microbial biomass, and basal respiration. Results revealed higher content and stock of C and N in areas with CLI. The principal humic substance reported was humin, and higher concentrations of C associated with minerals were present in areas under more recent CLI adoption (2 and 4 years). We demonstrated that the adoption of CLI, even if recent, leads to immediate increases in the concentrations of C and its fractions as a result of using forage crops. NT for 14 years and CLI for 8 years exhibited higher levels of C management and higher soil biological activity due to the greater stability of these systems.

Light soils are more susceptible to degradation and need to be exploited in a conservational manner, thus avoiding rapid degradation. The objective of this study was to evaluate the physical-hydraulic properties of an Ultisol under no-tillage and crop-livestock integration in the Cerrado of eastern Maranhão state, Brazil. The evaluated managements were one area under no-tillage system for fourteen years (soybean/ millet) and three areas with different histories of adoption of the crop-livestock integration (CLI) system under no-tillage (soybean/millet), with the difference being: times of entry with CLI (2, 4 and 8 years), as well as a native Cerrado area, considered a control. Soil collection was carried out in June 2018 at depths of 0.00-0.10, 0.10-0.20, 0.20-0.30 and 0.30-0.50 m. Disturbed and undisturbed samples were collected to determine the following variables: bulk density, porosity, resistance to penetration, retention curve and available water capacity. Data were subjected to the calculation of means and confidence intervals (95%). The area with a recent history of crop-livestock integration showed better density, porosity, resistance to penetration, water storage capacity and available water. No-tillage for fourteen years leads to high resistance to penetration, less porosity and low water storage capacity. The integrated system (CLI) improves the quality of the physical- hydraulic properties and the values found are similar to those observed in an area under native vegetation.

Scarification improves soil physical conditions, resulting in suitable conditions for root growth in crops and water infiltration. This study evaluates the effects of mechanical scarification on the physical attributes of a Yellow Oxisol cultivated with soybean under no-tillage in the Savanna of Piauí state, Brazil. Three areas under soybean cultivation were chosen, namely: one in the second year of cultivation under no-tillage (CS2); one cultivated for ten years under no-tillage (CS10); one area with soybeans identical to the previous one, but with scarification for a year (ESC); and a native Savana vegetation (CV), used as control. Density, macroporosity, microporosity, total porosity, and soil resistance to penetration at depths between 0-0.20 and 0.20-0.40 m were evaluated. The CS area showed decreased physical indicator values compared to the other management systems. Scarification was efficient in improving soil density, total porosity, and soil resistance to penetration at depths between 0.00 and 0.20 m. CS2 and CV areas showed more favorable physical indicator values. Through multivariate analyses, it was possible to identify which physical variables correlated with each type of soil management and the effects of these managements on the physical characteristics of the soil studied.