ACCOUNTING SPATIAL VARIABILITY OF SOIL PH, EC AND OC AT DIFFERENT SAMPLING INTENSITIES IN RICE CROP USING GEOSTATISTICS

Abstract

The aim of this paper was to quantify and evaluate the spatial distribution of soil pH, EC and OC in different grid
sampling intensities using descriptive statistics and geostatistics. The study was carried out in a farmer field from Machapur village of Siddipet district, Telangana. Using GPS, a 14.2 x 14.2 m grid sampling size was set, comprising 200 samples per 10 acres. In each grid positioned on the field, soil samples at a depth of 0 - 20 cm were extracted. Soil pH, EC and OC were determined. By
deleting the alternative soil samples from the 200 grids (sequential sampling), sampling intensities of 100, 50, 25, and 10 were
established, with a decreased number of samples per selected area (10 acres). Each soil attribute was submitted to descriptive
statistical and geostatistical analysis at each sampling intensity. An experimental semivariogram was developed to understand the spatial dependence structure. The attributes pH, EC and OC showed spatial correlation in almost all sampling intensities, except for the sampling intensity of 10 for OC.