Implications of the variability in soil penetration resistance for statistical analysis

Revista Brasileira de Ciência do Solo

Paulo Ivonir Gubiani¹  José Miguel Reichert²  Dalvan José Reinert²  Neiva Somavilla Gelain¹ 

[1] ,UFSM Department of Soils

关键词: compaction;    coefficient of variation;    normality;    compactação;    coeficiente de variação;    normalidade;   

DOI  :  10.1590/S0100-06832011000500003

来源: SciELO

【 摘 要 】

Soil penetration resistance (PR) is a measure of soil compaction closely related to soil structure and plant growth. However, the variability in PR hampers the statistical analyses. This study aimed to evaluate the variability of soil PR on the efficiency of parametric and nonparametric analyses in indentifying significant effects of soil compaction and to classify the coefficient of variation of PR into low, medium, high and very high. On six dates, the PR of a typical dystrophic Red Ultisol under continuous no-tillage for 16 years was measured. Three tillage and/or traffic conditions were established with the application of: (i) no chiseling or additional traffic, (ii) additional compaction, and (iii) chiseling. On each date, the nineteen PR data (measured at every 1.5 cm to a depth of 28.5 cm) were grouped in layers with different thickness. In each layer, the treatment effects were evaluated by variance (ANOVA) and Kruskal-Wallis analyses in a completely randomized design, and the coefficients of variation of all analyses were classified (low, intermediate, high and very high). The ANOVA performed better in discriminating the compaction effects, but the rejection rate of null hypothesis decreased from 100 to 80 % when the coefficient of variation increased from 15 to 26 %. The values of 15 and 26 % were the thresholds separating the low/intermediate and the high/very high coefficient variation classes of PR in this Ultisol.

【 授权许可】

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