Spatial variability of soil properties of intensively cultivated rice soils of selected command areas of Karnataka

Abstract

The spatial distribution of soil properties and plant available Si was studied in three important rice producing command areas of Karnataka by collecting random georeferenced surface (0-15cm) soil samples using GPS and GIS techniques. The soil samples were analysed for different soil properties and plant available Si and the data along with GPS reading were used for the preparation of soil thematic maps using interpolation method and the interpolated maps were analysed with geostatistical parameters and the corresponding kriging maps for pH, electrical conductivity (EC), soil organic carbon (SOC), available nitrogen, phosphorus, potassium and plant available Si (CCSi and AASi) were prepared. These soil samples were categorized as low, medium and high as per criteria followed by soil testing laboratories. The content of soil pH, EC, OC, CEC, sand, silt and clay in surface soils varied from 5.2- 8.7, 0.05-0.49 dS m-1 , 2.2-17.5 g kg-1 , 3.6- 26.5 c mol (p+ ) kg-1 , 20.4-85.6, 0.9-59.7 and 1.9-47.8%, 15.7-65.4 mg g-1 and 19.2-106.7 mg g-1 , respectively. The available nitrogen (89.6- 313.6 kg ha-1 ) was low whereas, phosphorus (10.4-206.9 P2O5 kg ha-1 ) and available K2O (68.9-516.9 K2O kg ha-1 ) were low to medium in range. The CCSi and AASi content ranged from 15.7-65.4 mg g-1 and 20.0-106.7 mg g-1 , respectively