Establishment of homogeneous zones in a soil of alluvial origin

Determinação de zonas homogêneas num solo de origem fluvial

ABSTRACT

Soils have the ability to maintain plant growth and biological activity due to their physical and chemical properties. The aim of this study was to observe the spatial distribution of some chemical properties of the soil, such as pH, organic matter (OM), electrical conductivity (EC), effective cation exchange capacity (ECEC), sulfur (S) and aluminum (Al) content and to establish zones with homogeneous chemical characteristics using the MULTISPATI-PCA technique and the fuzzy c-means algorithm. The study area was located in the Tundama and Sugamuxi Valleys (Boyacá, Colombia) with an area of ​​8,017 ha. Chemical properties such as pH, OM, EC, S, Al, and ECEC were indicators of the chemical degradation of these soils. Four homogeneous zones were identified. The first zone represents areas with acidity and excessive sulfur, with a pH of 4.54, 15.88% OM, 3.19 dS m^-1 EC, 2.47 meq 100 g^-1 Al and 365.59 meq 100 g^-1 S. In contrast, the second zone represents areas with a high self-neutralizing capacity, with a pH of 5.98, 4.22% OM, 0.75 dS m^-1 EC, 0.20 meq 100 g^-1 Al and 44.64 meq 100 g^-1 S. Zone three showed a high similarity with the first two, except for its EC and S contents. Finally, zone four showed similarity with the first, except in OM, EC and S contents. These data show that S and EC influenced the homogeneous zones because the soils in this area are called acid sulfate soils.

Index terms:
Geostatistics; semivariogram; soil degradation; Multispati-PCA; spatial distribution.