Predictive Mapping for Soil pH and Phosphate based on Kriging Interpolation

Abstract

Spatial variability can be the main cause of uneven plant growth, but this has not received much attention in the field. Spatial variability in soil chemical properties (soil pH, P) can be calculated using a geostatistics approach. The main objective of this research was to make a predictive mapping for soil pH and phosphate based on Kriging interpolation. The research resulted that the maps generated by Kriging interpolation showed similar patterns of high leaching and erosion effects in the landscape. The range of spatial variability of soils was found between 250-350 m with an average value of 300 m. Therefore, an effective survey can be carried out with a density every 120 m (rounded up to 100 m). The elevation range with an average value of 700 m can be said to be a maximum of 50% causing the increase in spatial variability of soils. This was evidenced by the high difference between the soil characters range (250-350 m) and the elevation range (700 m). The spatial variability of soil characters did not only depend on the relief form, but also on the dynamics of the groundwater interflow. A combination of soil pH, available P provided good indices for high leaching in the landscape. The high spatial variability for soil pH and available P indicated the result of the weathering process of the parent material, which was influenced by slopes, land use, intensive vertical and lateral groundwater flows. Cation leaching was the main process causing systematic spatial variability of soils in the landscape. Therefore, this leaching process has to be managed.