Characterizing, Predicting, and Mapping Soil Available Phosphor, pH, and Electrical Conductivity in Rubber Plantation Based on Three Different Methods of Ordinary Kriging in GIS Environment

Abstract

Soils in rubber plantations have unique characteristics due to their prolonged and excessive uses. These practices have changed soil qualities, production, and the geographical distribution of soil conditions. For this reason, research on the spatial analysis of soil attributes in rubber plantations is essential. Although it is acknowledged that there are proven methods for accounting for geographical variability, their use in rubber plantations is still somewhat restricted. Evidence also demonstrates ongoing debate and variation in the findings on the capacity of methods to predict spatial variability. Therefore, the primary goal of this study is to examine how well various approaches perform when using ordinary kriging to analyze spatial variability of three soil properties: Soil Available Potassium (SAP), pH, and Electrical Conductivity. The methodology employed in this work includes (a) grid sampling for data collection, (b) interpolation using Ordinary kriging with three methods (exponential, spherical, and Gaussian), (c) mapping, and (d) evaluation. The findings of this study demonstrate that semi-variogram analysis using three distinct methods yields somewhat varied outcomes with accuracy in higher order from SAP, soil EC, and soil pH. The results of this study also show that the different methods have unique characteristics when representing spatial structure.  These findings suggested that the number of samples and the selection of interpolation techniques are essential factors in studying these three soil properties and determining the accuracy of the results.