Spade methods to visually evaluate soil structural quality (Sq) are simple, quick, cheap and can be used by farmers, gardeners, consultants and the scientific community. However, European and Brazilian users of one such method, viz. visual evaluation of soil structure (VESS) which is a development of the Peerlkamp test, have been concerned about its subjectivity. The method of soil slice break‐up and operator influence on scores have been questioned. Thus, our aim was to make soil scoring by the VESS technique more objective and thus to revise the scoring guide. We compared scoring with normal breaking up of the soil slice by hand with scoring after breaking up the slice by dropping (drop shatter) to make the soil break‐up more operator independent. After slice break‐up, aggregates were split by hand and their internal porosity was evaluated to develop the use of visible porosity as an aid to scoring. This proved inconclusive on its own, so a method of reducing larger aggregates to 1.5–2.0 cm core fragments and describing their shape and porosity was developed to score soil Sq. Breaking up a spadeful of soil by hand or by dropping resulted in the same Sq score. The method of reducing aggregates and evaluation of their shape improved VESS, particularly in the middle range of soil quality and the revised chart is shown. VESS was sensitive to changes in Sq in layers within the profile and its use for diagnosing Sq in different layers allows targeted soil improvement by tillage.

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Cherubin, Maurício R.; Franco, André L.C.; Guimarães, Rachel M.L.; Tormena, Cássio A.; Cerri, Carlos E. P.; Karlen, Douglas; and Cerri, Carlos C., "Assessing soil structural quality under Brazilian sugarcane expansion areas using Visual Evaluation of Soil Structure (VESS)" (2017 Increasing global demand for biofuel has accelerated land-use change (LUC) in Brazil, primarily through the planting of sugarcane (Saccharum officinarum) to replace degraded pastures. The intensive mechanization associated with this LUC has increased concerns regarding structural quality of Brazilian tropical soils. Through decades of research focusing on identifying sensitive indicators of soil degradation due to land use and management, the Visual Evaluation of Soil Structure (VESS) method has emerged as a simple, fast, reliable and accurate semi-quantitative approach for assessing soil structure changes. VESS integrates soil properties related to size, strength and porosity of aggregates, and root characteristics into a single score (Sq -structural quality) that ranges from 1 (good structural quality) to 5 (poor structural quality). Although the VESS method was developed for temperate soils, it has been used successfully as an indicator of soil and crop management practice effects on structural quality of tropical and subtropical soils. Our objectives were to evaluate soil structural quality changes associated with a LUC sequence (i.e., native vegetation to pasture to sugarcane) at three sites under Oxisols, Alfisols and Ultisols across centralsouthern Brazil using the VESS; and to correlate VESS scores with quantitative measurements of soil physical properties. Average VESS scores were 2.0, 2.7, and 3.1 for native vegetation, pasture, and sugarcane, respectively. Overall the VESS method was able to detect soil structural quality changes under LUC for sugarcane cultivation, indicating a decrease in soil quality from native vegetation through pasture to sugarcane. The VESS scores were significantly correlated with quantitative soil physical property measurements, suggesting VESS is a reliable indicator of soil structural quality in tropical soils. A VESS score Sq = 3.0 seems to be suitable as a guide for management decisions. We conclude that VESS scores provide an efficient method to identify impacts of sugarcane expansion on soil structural quality, and recommend that VESS assessment be incorporated into monitoring protocols for evaluating not only sugarcane expansion areas, but also overall soil quality/health in Brazil.

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RESUMOO manejo da irrigação tem-se baseado no controle do potencial da água no solo (Ψ Ψ Ψ Ψ Ψ) como fator limitante do crescimento das plantas. Entretanto, outras variáveis podem influenciar a cultura mesmo que o Ψ Ψ Ψ Ψ Ψ não seja limitante. O Intervalo Hídrico Ótimo (IHO) é um conceito de disponibilidade de água no solo que leva em consideração a porosidade de aeração e a resistência do solo à penetração em adição ao Ψ Ψ Ψ Ψ Ψ. O objetivo deste estudo foi quantificar o IHO num Nitossolo Vermelho distroférrico irrigado e utilizá-lo no estabelecimento de critérios para o manejo de água e do solo em áreas irrigadas. A resistência do solo à penetração foi a variável que limitou o IHO com maior frequência, diminuindo sua magnitude com o aumento da densidade do solo (Ds). Com o aumento da Ds, ocorreu redução na frequência com que θ θ θ θ θ manteve-se dentro dos limites do IHO. A Ds crítica (Dsc) foi de 1,40 Mg m -3 , indicando severa degradação física do solo para Ds > Dsc. Para Ds < 1,28 Mg m -3 , o Ψ Ψ Ψ Ψ Ψ de -800 hPa utilizado frequentemente para o controle da irrigação por meio de tensiômetros caracterizou o limite inferior do IHO. Para 1,28 < Ds ≤ ≤ ≤ ≤ ≤ 1,40 Mg m -3 , o limite inferior do IHO foi determinado pela RP e, nestas condições, a adoção de Ψ Ψ Ψ Ψ Ψ igual a -800 hPa como limite para a aplicação de água estabelece restrições físicas às plantas devido à elevada RP. Neste caso, o mapeamento de áreas com Ds uniformes poderia ser utilizado para o manejo do Ψ Ψ Ψ Ψ Ψ para a manutenção da RP < 2,0 MPa. Nas áreas em que a Ds < 1,28 Mg m -3 pode ocorrer maior secamento do solo sem que ocorra RP > 2,0 MPa; para 1,28 < Ds ≤ ≤ ≤ ≤ ≤ 1,40 Mg m -3 deve-se manter Ψ Ψ Ψ Ψ Ψ > -800 hPa visando ao controle da RP. Para áreas em que Ds > Dsc, medidas que visem a redução da Ds poderiam ser tomadas em função da severa degradação física do solo.Termos de indexação: irrigação, qualidade física do solo, resistência do solo à penetração.

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