Curvatura Da Superfície E Seu Efeito Na Variabilidade Espacial Dos Atributos Do Solo, Pinheiral - Rj/br

Understanding the spatial variability of soil chemical and physical attributes is important for improving management practices and soil conservation. In turn, the spatial variability of soil properties results from variation in morphological relief characteristics. Thus, the purpose of this study was to evaluate the influence of landform curvature on the spatial variability of soil chemical and physical attributes in the Mar de Morros region (Pinheiral-Rio de Janeiro State, Brazil). Two adjacent landforms were selected with convex and concave curvature and sampled in a regularly spaced grid of 10 meters. A total of 56 soil samples (0-5 cm depth) from the two landforms were collected and analyzed for physical and chemical attributes. The data were analyzed using descriptive statistics and geostatistics. All chemical attributes showed random patterns of spatial variability in both landforms. The concave landform had higher values of pH and potassium and lower values of aluminum than the convex landform. In contrast, silt content showed spatial dependence in both the concave and convex landforms. Bulk density and clay showed spatial dependence in the convex landform. Bulk density and silt content increased from the shoulder to the footslope of both landforms. The results show that, for this study area, landform curvature has more influence on the spatial dependence of soil physical attributes than of soil chemical properties. © 2016, Federal University of Lavras. All rights reserved.22443143

Efeito prolongado de sistemas de preparo do solo com e sem cultivo de soqueira de cana crua em algumas propriedades físicas do solo Long-term effect of soil tillage systems with and without tillage of green-cane stump in soil physical properties

Este trabalho foi conduzido em Latossolo Vermelho distrófico típico, sob cultivo de cana crua, com o objetivo de avaliar o efeito prolongado de sistemas de preparo do solo, com e sem cultivo da soqueira, e épocas de amostragem sobre algumas propriedades físicas do solo. O delineamento experimental foi o de blocos ao acaso, em esquema de parcelas subsubdivididas, sendo os tratamentos principais quatro sistemas de preparo do solo: (i) controle da soqueira com duas gradagens, subsolagem e mais uma gradagem de nivelamento; (ii) controle da soqueira com herbicida e uma subsolagem; (iii) controle da soqueira com herbicida; (iv) controle da soqueira com herbicida, aração com arado de aivecas e uma gradagem de nivelamento. Os tratamentos secundários foram: com cultivo e sem cultivo da soqueira. Os tratamentos ternários foram as épocas de avaliação: dois dias antes e após a quarta colheita da cultura. A porosidade total, macroporosidade, microporosidade e densidade do solo foram avaliadas, além do perfilhamento e da produtividade da cultura. Após quatro sucessivas colheitas de cana crua, houve redução da macroporosidade com aumento da microporosidade nas camadas abaixo de 10 cm e aumento da densidade do solo entre 20 e 50 cm. A densidade do solo não foi alterada de modo consistente em função de todos os tratamentos testados. O cultivo da soqueira favoreceu o aumento da macroporosidade com decréscimo na microporosidade, e o efeito inverso foi observado após a colheita. Os sistemas de preparo do solo e de cultivo da soqueira não afetaram o perfilhamento e a produtividade da cultura.<br>This work was carried out at the field conditions in a Typic Haplustox soil with green-cane crop with the objective to evaluate long-term effect of soil tillage systems with and without tillage of stump in soil physical properties. A complete randomized blocks in split-split-plots arrangement of treatments were used. The principal treatments were four soil tillage systems: (i) control of stumps with two harrowing, subsoiling plus a levelling harrowing; (ii) control of stumps with herbicide and a subsoiling; (iii) control of stumps with herbicide; (iv) control of stumps with herbicide, subsoiling plus a levelling harrowing. Secondary treatments were stump tillage systems: with and without stump tillage. The split-split-plot treatments were the evaluation time: before and after the 4th cane harvest. Total porosity, macroporosity, microporosity and bulk density were evaluated, besides the tillering and yield of the crop. After four harvests of green-cane there were reduction of the macroporosity with increase of the microporosity in the soil layers below 10 cm, and an increase of soil bulk density in the layer between 20 and 50 cm. Soil bulk density wasn't altered in a consistent way as affected by all treatments. Stump tillage promoted an increased in the macroporosity with decrease of the microporosity, and the inverse effect was observed after the harvest. Soil tillage system and stump tillage didn't affect both tillering and yield of green-cane