Management units based on the physical properties of an oxisol

Abstract

In Colombia, the zone of the greatest agricultural expansion includes soils within the native savanna system. These soils are Oxisols, which have a stable structure but are susceptible to physical degradation. The objective of this paper was to study the spatial variability of the soil physical properties with the aim of determining management units. This study was carried out in the municipality of Puerto Gaitán, Meta, Colombia, in an area of 5100 ha where nodes were placed every 320 m in a grid. The samples were taken from the surface (AH) and subsurface (BH) horizons in which the texture, pore distribution, saturated hydraulic conductivity (KS), bulk density (BD) and soil particle density (PD) were determined. The data analysis was conducted using descriptive statistics, geostatistics and multivariate analysis. The predominant textures of the soil were loam and sandy loam. High values of BD, high values of microporosity, low presence of mesopores and slow KS were found, which result in physical limitations for adequate development of crops. The BD and the total porosity were the properties that best characterized the soil and showed the greatest number of signifcant correlations with the other physical properties. The KS was the only property that did not show spatial dependence. Geostatistics allowed the identifcation of spatial variability patterns, estimation of the properties at non-sampled sites, and identifcation of management units of the properties that ft the semivariogram models. Multivariate analysis identifed the most representative properties of the soil and permitted the establishment of management units.