English

Guilherme Kruger Bartels,Viviane Santos Silva Terra,Felício Cassalho,Dalvan Jose Reinert,Luciana Shigihara Lima,Gilberto Loguercio Collares

doi:10.5897/ajar2016.11812

Abstract

In order to provide an adequate usage to agricultural soils it is crucial to comprehend the soil physical attributes and their spatial variability. The variability of soil attributes is dependent on several formation processes and interactions. To properly describe such complex variability, the statistical methods used must incorporate the spatial and temporal influences. In this context, the present study was developed with the objective of evaluating the spatial variability of physical and hydraulic soil attributes, such as sand, clay and silt contents, soil macroporosity (Ma), soil microporosity (Mi), soil total porosity (TP), soil bulk density (BD), hydraulic conductivity (K), water contents at field capacity (tension of 10 kPa) and permanent wilting point (tension of 1500 kPa) (θFc and θPWP), in a watershed, located in the Sul-Rio-Grandense Shield, in the South of Brazil, through the geoestatistics analysis based on Ordinary Kriging. It was found a better performance of exponential model for the semivariograms of most physical and hydraulic soil attribute in the 0-0.15 and 0.15 to 0.25 m layers. Spatial dependence was observed for all the soil physical and hydraulic attributes studied, classifying as high for the variables macroporosity (0 to 0.15 m) and clay (0.15 to 0.25 m), with the other variables classified as moderate spatial dependence. Besides, the variables K and macroporosity presented a high heterogeneity in relation to the average, with K in the surface layer and the variables clay, Ma, K and qPWP in the subsurface layer not presenting normality according to Shapiro and Wilk test (p ≤ 0.05).   Key words: Ordinary kriging, semivariogram, physical and hydraulic soil attributes, Shapiro and Wilk test, exponential.

Highlights

In order to have an efficient use of natural resources, understanding soil properties, as well as its geographical distribution, mapping soil attributes becomes an important tool in the development of an adequate plan for soil management (Dessalegn et al, 2014)
The present study was developed with the objective of evaluating the spatial variability of physical and hydraulic soil attributes, such as sand, clay and silt contents, soil macroporosity (Ma), soil microporosity (Mi), soil total porosity (TP), soil bulk density (BD), hydraulic conductivity (K), water contents at field capacity and permanent wilting point, in a watershed, located in the Sul-RioGrandense Shield, in the South of Brazil, through the geoestatistics analysis based on Ordinary Kriging
It was found a better performance of exponential model for the semivariograms of most physical and hydraulic soil attribute in the 0-0.15 and 0.15 to 0.25 m layers

Summary

Introduction

In order to have an efficient use of natural resources, understanding soil properties, as well as its geographical distribution, mapping soil attributes becomes an important tool in the development of an adequate plan for soil management (Dessalegn et al, 2014). Kruger et al 5037 formation factors and processes interaction such as, the climate, the topography, the material origin and the vegetation (Rezaei and Gilkes, 2005a; Wang et al, 2009). According to the same authors, the interaction between the factors and processes occurs both in spatial and time scale, which can be altered locally mainly through soil erosion. According to Gonçalves et al (2001) the study of spatial and time variability is of extreme importance concerning the attributes that influence the soil water storage, such as: soil depth, infiltration capacity, topography and the regional climate. The attributes that present variability induced by management practices are, among others, the surface layer thickness, structure, bulk density, porosity and hydraulic conductivity of the saturated soil, are more dynamic in space and time (Rezaei and Gilkes, 2005b)

Methods

Results

Conclusion