Spatial Distribution of Soil Nutrient Status of Biswanath District, Assam, North East India

Rice-based cropping system is a key for food security in Assam. However, the productivity of such systems has declined continuously due to deterioration in soil fertility owing mainly to faulty agricultural practices. The study was carried out to study the nutrient status of soils of the Biswanath district of Assam in the year 2021. A total of 200 no of geo-reference surface (up to 30 cm) soil samples were collected. The coefficient of variation (CV) was used for the interpretation of the variability of the indicators. Available phosphorous, available potassium DTPA-iron, DTPA-manganese, DTPA-zinc, and DTPA-copper were identified to be the most variable soil indicators (CV > 35%). Electrical conductivity, organic carbon, available nitrogen, and cation exchange capacity, were found as the moderately variable parameters (CV 15–35%). The least variation (CV < 15) was found pH. The mean pH, electrical conductivity and organic carbon were 5.23, 0.54 ds/m, and 0.81 percent respectively. The cation exchange capacity of the soil varied from 4.40 to 11.60 cmol(p+)/kg with the mean value of 6.74cmol(p+) /kg. The available nitrogen, available potassium and available phosphorus were 380.01kg /ha, 169.00 kg/ha and 38.01 kg/ha. The district's respective DTPA-Fe, DTPA-Cu, DTPA-Mn, and DTPA-Zn levels were found to be 83.34 mg/kg, 2.59 mg/kg, 22.25 mg/kg, and 0.79 mg/kg. The spatial distribution of each parameter was presented on the GIS platform for easy availability through IDW method of interpolation.