Spatial Variability of Soil Properties in Brahmaputra Plains of North-eastern India: A Geostatistical Approach

摘要

The objective of this study was to determine, the degree of spatial variability of pH, organic carbon (OC), available nitrogen (AN) and available potassium (AK) of Goalpara district of Assam. A total of 1397 soil samples from a depth of 0-25 cm at anapproximate interval of 1 km were collected over the entire district. Data were analyzed both statistically and geostatistically on the basis of semivariogram. Soil properties showed large variability with greatest variation observed in AK (42%) whereasthe smallest variation was in pH (16%). The semivariogram for all soil properties were best fitted by exponential models and showed a highest (3.8 km) range for pH and lowest (2.0 km) for AN. The nugget/sill ratio indicates a strong dependence for pH (19%), moderate spatial dependence for OC (60%) and a weak spatial dependence for other soil properties. Evaluation of spatial maps indicated that except for AN, kriging could successfully interpolate other soil properties. Soil pH was significantly negatively correlated with OC (r = -0.434**) and AN (r = -0.228**). A significant positive relationship was observed between OC with AN (r = 0.498**) and AK (r = 0.119**).