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.

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Resumo O objetivo deste trabalho foi avaliar a condição física e a potencialidade de uso agrícola de um solo construído após mineração com carvão, além do desenvolvimento radicular de gramíneas tropicais nesse solo, tendo-se considerado diferentes períodos de revegetação. O solo foi construído no início de 2003, e o experimento instalado em novembro/dezembro de 2007. A condição física do solo construído foi avaliada nas parcelas ocupadas por gramíneas perenes, como Urochloa humidicola, Panicum maximum e U. brizantha. Em julho de 2012, foram coletadas amostras de solo com estrutura preservada e não preservada para a determinação dos atributos físico-químicos, nas camadas de 0,00-0,10, 0,10-0,20 e 0,20-0,30 m. Monólitos de solo foram coletados para caracterização do sistema radicular das diferentes gramíneas. Após 58 meses de revegetação, a condição física do solo construído ainda é inadequada ao uso agrícola que envolva práticas mais intensivas de manejo de solo. Entre as camadas avaliadas, somente a de 0,00-0,10 m fornece condições para que o solo cumpra suas funções no ecossistema. Urochloa brizantha mostra-se mais promissora para a recuperação da estrutura do solo na camada de 0,00-0,10 m, e a densidade radicular foi o atributo mais sensível para a diferenciação do desenvolvimento potencial das diferentes espécies nesta camada.

Changes in the soil structural quality have caused alterations in root growth and agricultural yield. With the purpose of finding critical values of physical parameters and alternative, viable and suitable ways of minimize the soil degradation, this study aimed at quantifying aggregate tensile strength (TS), friability (F), bull density (Bd), total porosity (Tp), macroporosity (Ma), penetration resistance (PR) and total organic carbon (TOC). Relations were established to estimate the structural quality of some parameters of an Ultisol under different uses. The study was carried out on a farm, in the rural area of RS, inserted in the Arroio Moreira waterbasin, Brazil. Disturbed and undisturbed samples were collected from the 0.00 to 0.10 m layer. Regarding TS and soil use, 900 samples were selected, totalling 2700 aggregates. Undisturbed samples (135) were collected for the evaluation of Bd, porosity and PR. The TOC was quantified using 45 aggregates through the dry combustion method. All physical parameters with exception of F are important in monitoring the structural quality.The lowest values of TS, PR and Bd were verified in the soil under fallow, and the highest ones in the soil under pasture. An inverse relation between TS and TOC and between Bd and TOC was verified. Critical values of Bd and TS to crop development might be estimated from the PR.

Estimation of soil loss susceptibility is of great importance for the management of watersheds. Thus, several models for soil loss prediction have been proposed. This study estimated the total annual soil loss for the Santa Rita watershed, located in southern Brazil, using the Revised Universal Soil Loss Equation. In addition, a classification to soil loss index (ISL) was proposed to identify regions with critical soil loss values. Altitude, slope, land use, and soil class data were applied to the model, in addition to spatial information for 78 soil samples collected within the study area. It was found that there is an average annual loss of 35.94 Mg ha -1 year -1 , with the most substantial loss occurring in areas with predominantly exposed soil and annual cropping. Furthermore, the ISL values indicated that approximately 50% of the study area is experiencing erosion estimates above the tolerable limit. Results emphasize the need for changes in conservation and application practices present in the watershed, considering land use and soil bearing capacity.