Spatial variability of soil physical properties as a result of different tillage systems / Variabilidade espacial das propriedades físicas do solo em função do preparo de solo

Abstract

Geostatistical tools allow soil physical properties to be monitored in order to describe the pattern of spatial variability and indicates the places with higher variation. Therefore, the purpose of this study is to assess the spatial variability of physical properties of soils under direct seeding and conventional tillage, using a native forest soil profile as reference. The areas where the samples were collected belong to the Federal University of Viçosa in the municipality of Viçosa in the state of Minas Gerais (Brazil). The studied soil physical properties were density, hydraulic conductivity, total porosity and moisture. The GS+ was used in order to do spatial distribution analysis and semivariograms. The spatial dependence index was fixed by the parameters based on the relative size of the nugget effect and sill. It was considered as strong spatial dependence when ? 25%, moderate spatial dependence between 26% and 74% and weak spatial dependence ? 75%. The range achieved in this study was higher than the distances between the sample points, proving the spatial continuity of the studied parameters. The forest area presented the lowest value of moisture and the highest value of hydraulic conductivity. Direct seeding area presented the highest density value and the lowest hydraulic conductivity when compared to the other two areas. Conventional tillage area had the highest total porosity in comparison to the other areas due to greater soil inversion.  The spatial dependence indexes were classified as moderate for the variables soil density, total porosity and saturated hydraulic conductivity.