Abstract The present study assessed the spatial distribution of soil fertility parameters across selected agro-climatic zones of Karnataka using geostatistical techniques. A total of 10 852 geo-referenced surface soil samples were collected and analysed for soil pH, organic carbon, available N, P, K, S, B and DTPA-extractable Zn. The results showed considerable variation in soil fertility status among the agro-climatic zones. Organic carbon and available nitrogen were predominantly low in dry zones, whereas available phosphorus, potassium and sulphur ranged from low to medium across the region. Geostatistical analysis revealed that exponential and spherical models were the best-fit semivariogram models for most soil properties. Semivariogram parameters indicated high spatial variability, with range values for micronutrients exceeding the grid interval (320 m), demonstrating the reliability of the sampling density for predicting spatial variability. Zinc and boron exhibited moderate to weak spatial dependence, suggesting that their distribution is largely influenced by management practices and inherent soil characteristics. The study highlights the importance of spatial variability assessment for precision nutrient management and demonstrates the usefulness of geostatistical modelling for developing soil fertility maps.
Sathish et al. (Tue,) studied this question.