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The "Visual Evaluation of Soil Structure" (VESS) is a method used primarily to evaluate the soil structural quality of Oxisols in Brazil and secondly for more specific research, consultancy, and teaching purposes. Since the methodology was never applied and compared with laboratory evaluations of physical properties of hydromorphic soils of the Pampa biome in the south of Brazil, this study evaluated the use of VESS as a visual indicator of the structure quality of a typic eutrophic Albaqualf soil under native grassland, crop-livestock integration, no-tillage, and conventional management systems. Experimental areas with these different management systems were subjected to visual (VESS) and laboratory evaluation of the soil structure. The laboratory evaluation was based on traditional methods and on measurements of bulk density, porosity, aggregate mean weight diameter, aggregate tensile strength (ATS), and total organic carbon (TOC). It was concluded that VESS was efficient in differentiating the management system. The management systems based on minimum soil disturbance and mulching with crop residues improved the soil quality, as evidenced by the VESS scores, bulk density, porosity, aggregation, and organic carbon. The TOC content was inversely related with ATS. The quality of a typic eutrophic Albaqualf was benefitted by organic matter in the surface layer.

Resumo -O objetivo deste trabalho foi avaliar a qualidade física e as frações da matéria orgânica de um Planossolo sob sistema plantio direto (SPD), com diferentes tempos de implantação, no Sul do Brasil. Amostras de solo foram coletadas nas camadas de 0,00-0,03, 0,03-0,06, 0,06-0,10 e 0,10-0,20 m, tendo-se determinado: a porosidade total (Pt); a macroporosidade (Ma); a microporosidade (Mi); a resistência do solo à penetração (Rp); a densidade (Ds); os macro e microagregados; o diâmetro médio ponderado dos agregados (DMP); o carbono orgânico total (COT); o carbono das frações leve livre (FLL), leve oclusa (FLO) e pesada (FP); os estoques de carbono (EstC), os índices de labilidade (ILC), de estoque (IEC) e de manejo do carbono (IMC). O tempo de implantação SPD aumentou a Pt, a Ma, os EstC, e diminuiu a Mi, a Rp e a Ds. O SPD promove os atributos DMP, ILC, IEC e IMC a partir do quinto ano de implantação, e, portanto, melhora a qualidade física do solo.Termos para indexação: dinâmica da matéria orgânica, estruturação do solo, fracionamento da matéria orgânica, índices de labilidade, solo hidromórfico, solos de várzea. Physical quality and organic matter fractions of an Alfisol under no-tillageAbstract -The objective of this work was to evaluate the physical quality and the organic matter fractions of an Alfisol soil under no-tillage (NT) with different deployment times in Southern Brazil. Soil samples were taken at the 0.00-0.03, 0.03-0.06, 0.06-0.10, and 0.10-0.20-m depths, for determining: total porosity (Pt); macroporosity (Ma); microporosity (Mi); soil penetration resistance (Rp); bulk density (Ds); macro-and microaggregates; mean weight diameter (MWD) of soil aggregates; total organic carbon content (TOC); the free light (FLL), light occluded (FLO), and heavy (FP) carbon fractions; carbon stocks (EstC); and the lability (ILC), stock (IEC), and carbon management (IMC) indexes. SPD deployment time increased Pt, Ma, and EstC, and decreased Mi, RP, Ds. NT promotes MWD, ILC, IEC, and IMC after five years of deployment, and, therefore, it improves soil physical quality.

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Resumo -O objetivo deste trabalho foi avaliar os efeitos do sistema plantio direto (PD) e do manejo com preparo convencional (PC) sobre atributos físicos e hídricos de um Planossolo Háplico cultivado com soja, em terras baixas do Sul do Brasil. Amostras indeformadas de solo foram coletadas às camadas de 0,00-0,10, 0,10-0,20 e 0,20-0,40 m, para a determinação dos atributos físico-hídricos, tendo-se monitorado o potencial mátrico do solo com sensores, ao longo de um ciclo de produção da soja. Os valores de macroporosidade foram menores do que 0,10 m 3 m -3 , independentemente do sistema de manejo do solo, o que restringe a possibilidade de cultivo da soja em sequeiro, pelo comprometimento da difusão de gases. Comparado ao PC, o PD promove a microporosidade na camada de 0,00-0,10 m, o que aumenta o conteúdo de água armazenada no solo e a disponibilidade hídrica para a cultura da soja, com reflexos positivos sobre a produtividade da cultura.Termos para indexação: Glycine max, cultivo mínimo, disponibilidade hídrica, porosidade do solo, terras baixas, várzeas. Physico-hydric conditions of an Alfisol cultivated with soybean under no-tillage and conventional tillageAbstract -The objective of this work was to evaluate the effects of no-tillage (NT) and conventional tillage (CT) on the physical and hydric properties of an Albaqualf soil cultivated with soybean, in the lowlands of Southern Brazil. Undisturbed soil samples were collected at the 0.00-0.10, 0.10-0.20, and 0.20-0.40-m soil layers, in order to determine soil physicohydric properties, by monitoring the soil matric potential with sensors, over a cycle of soybean production. Macroporosity values were lower than 0.10 m 3 m -3 , irrespectively of the soil management system, which restricts the possibility of rainfed soybean cultivation because it affects gas diffusion. In comparison to CT, NT increases microporosity at the 0.00-0.10-m soil layer, which increases soil water content and soil water availability for soybean crop, with positive effects on crop yield. Index terms: Glycine max, minimal tillage, soil water availability, soil porosity, lowlands, floodplains. IntroduçãoNo Rio Grande do Sul, há 5,4 milhões de hectares de terras baixas, o que representa 20% da área total do estado (Parfitt et al., 2014). Nessas áreas, predomina a produção de arroz irrigado, com os seguintes manejos: cultivo mínimo, 74,2% da área; preparo convencional, 15,7%; e pré-germinado, 10,1% (Irga, 2014). Mesmo incipiente, o sistema plantio direto vem ganhando espaço nesse ambiente, em culturas alternativas ao arroz irrigado, o que tem sido associado à expansão da rotação/sucessão de culturas de sequeiro nessas áreas. A adoção de sistemas de produção sustentáveis e conservacionistas, combinados com culturas alternativas dotadas de valor comercial e liquidez, como a soja, pode contribuir para a manutenção da competitividade produtiva nas terras baixas do RS (Vernetti Junior et al., 2009).Após um longo predomínio do preparo convencional do solo, associado à sucessão arroz-pecuária extensiv...

Due mainly to the taste and appearance, the strawberry stands out in relation to the other fruits. and for the presence of antioxidant compounds. However, little attention has been devoted to the impact of abiotic stresses on the quality of strawberry and its agronomic performance. On the present study, we evaluated the effect of two levels of DS (L1 -70% and L2 -50% of crop evapotranspiration) on the quality of strawberry fruit and on some agronomic and physiological variables. There was a dose-dependent reduction in the evaluated agronomic variables in the DS plants, and the content of some minerals in the fruit and leaves was modified. The activities of the oxidative enzymes were higher in the fruit of L2 treatment, and the content of sucrose, reduced sugars, phenolic compounds and the total antioxidant activity were increased in the fruit from L2 treatment; while those of anthocyanins and L-ascorbic acid were reduced in L1 and L2 treatments, respectively. The phenylalanine ammonia lyase gene was upregulated and other genes related to phenylpropanoid and ascorbate pathways were downregulated in the fruit of stressed plants. Thus, our results indicate that DS seems to be a promising strategy to improve the content of antioxidant compounds and sugars.Practical Application: Drought stress might be applied to induce antioxidant and sugars in strawberry fruit.

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