Geo-reference based soil fertility status in Hassan district of Karnataka, India for development of nutrient plan

The aim of the study was to evaluate the nutrient status and their relation with other properties of soil. For this purpose, 1320 geo-referenced surface soil samples from 015 cm depth using GPS were collected from eight taluks of Hassan district in southern Karnataka. The results showed that pH (3.72–9.71) and EC (0.02–1.79 dS m⁻¹) of soils were acidic to alkaline with non-saline nature. About 86.59% of the soils were found to be medium in available nitrogen (315.90 kg N ha⁻¹) and 55% of samples fall under high available phosphorus (>22.50 kg P₂O₅ ha⁻¹) category. The available potassium status in surface soils of different talukas ranged from 50 to 984 kg ha⁻¹. Available sulphur content in soil varied from 0.24 to 90.81 mg kg⁻¹, with 75% soils deficient in sulphur due to continuous removal of sulphur by crops. Zinc deficient was recorded in 55.44% of soil samples analyzed and 99.54% were deficiency in boron which ranged from 0.08 to 6.70 and 0.04 to 0.82 mg kg⁻¹, respectively. The remaining micronutrients (Fe, Cu and Mn) shown to be sufficient and their values ranged between 0.77 to 802.53, 0.03 to 6.78 and 1.08 to 81.35 mg kg⁻¹, respectively. Analytical data clearly indicated that all the nutrients were significantly correlated with each other suggesting the dynamic equilibrium exists among these nutrients.