GPS receivers for georeferencing of spatial variability of soil attributes

David L Rosalen,Diego S Siqueira,Marcos S Rodrigues,Flavia J C Brandão,Carlos A Chioderoli

doi:10.1590/s0100-69162011000600013

David L Rosalen, Diego S Siqueira + Show 3 more

Open Access

https://doi.org/10.1590/s0100-69162011000600013

Copy DOI

Abstract

The characterization of the spatial variability of soil attributes is essential to support agricultural practices in a sustainable manner. The use of geostatistics to characterize spatial variability of these attributes, such as soil resistance to penetration (RP) and gravimetric soil moisture (GM) is now usual practice in precision agriculture. The result of geostatistical analysis is dependent on the sample density and other factors according to the georeferencing methodology used. Thus, this study aimed to compare two methods of georeferencing to characterize the spatial variability of RP and GM as well as the spatial correlation of these variables. Sampling grid of 60 points spaced 20 m was used. For RP measurements, an electronic penetrometer was used and to determine the GM, a Dutch auger (0.0-0.1 m depth) was used. The samples were georeferenced using a GPS navigation receiver, Simple Point Positioning (SPP) with navigation GPS receiver, and Semi-Kinematic Relative Positioning (SKRP) with an L1 geodetic GPS receiver. The results indicated that the georeferencing conducted by PPS did not affect the characterization of spatial variability of RP or GM, neither the spatial structure relationship of these attributes.

Highlights

The spatial variability characterization of soil attributes is essential to promote sustainable agricultural practices. MCBRATNEY et al (2003) proposed the use of geostatistics, a numerical rating of tools to characterize spatial variability attributes, and improve mapping quality for agricultural and environmental purposes
STABILE & BALASTREIRE (2006) state that the GPS navigation receiver is not recommended for precision agriculture (PA) use, because it does not have adequate accuracy. These results indicate that the feasibility of using GPS navigation in PA is dependent on the application, as well as the desired accuracy
resistance to penetration (RP) showed very high variability, per its coefficient of variation (CV), as suggested by PIMENTEL-GOMEZ & GARCIA (2002), agreeing with the results obtained by RAMÍREZ-LÓPEZ et al (2008) in a Typic Haplustox, but contradictory to results reported by ROSA FILHO et al (2009), who observed average variability for RP

Summary

Introduction

The spatial variability characterization of soil attributes is essential to promote sustainable agricultural practices. MCBRATNEY et al (2003) proposed the use of geostatistics, a numerical rating of tools to characterize spatial variability attributes, and improve mapping quality for agricultural and environmental purposes. MCBRATNEY et al (2003) proposed the use of geostatistics, a numerical rating of tools to characterize spatial variability attributes, and improve mapping quality for agricultural and environmental purposes. The result of geostatistical analysis of these attributes is dependent on sample density (CORÁ & BERALDO, 2006) and other factors as the format of the sampling grid and the georeferencing method of the samples itself. The georeferenced points, on the other hand, are directly related to the quality limits (isolines) presented by the spatial variability map (composing). In determining the semivariance, paired sample points are used, which coordinates are provided by the positioning method adopted in the georeferencing; the quality of these coordinates may affect the semivariogram results

Objectives

Methods

Results

Conclusion