Identification of Soil Fertility Constraints using GIS for Sustainable Crop Production in the Watershed of Semi-arid Tropics

Abstract

The present investigation was carried out to identify soil fertility constraints and map the fertility status of Netranahalli watershed of Chitradurga district, Karnataka using geographic information system (GIS) and global positioning system (GPS). Eighty geo-referenced surface soil samples (0-30 cm) from the watershed located in Scarce Rainfall Zone of Karnataka were analyzed for their fertility parameters. Soil fertility maps were prepared for each parameter under GIS environment using Arc GIS v 10.4. Soils were slightly acidic to moderately alkaline (5.20-8.38) in reaction, non-saline (0.02-1.77 dS m-1) and low to high (2.6-13.6 g kg-1) in organic carbon (OC). The soils were low to high in available nitrogen (N) (166-704 kg ha-1), available phosphorus (P) (18.70-176.0 kg P2O5 ha-1) and available potassium (K) (128-935 kg K2O ha-1). The wide variation from deficient to sufficient was observed in the status of DTPA extractable zinc (Zn) (0.06-2.31 mg kg-1), iron (Fe) (1.81-29.1 mg kg-1) and manganese (Mn) (0.67-57.9 mg kg-1), whereas DTPA extractable copper (Cu) (0.36-6.05 mg kg-1) was almost sufficient. The cross-classification map revealed that 21.8% of the area has distinct and combined deficiency of OC and zinc. The fertility status in Netranahalli watershed revealed that soil OC, available N and Zn are important soil fertility constraints in the watershed. To buildup organic matter, Zn content and native N and maintain nutrient balance in the soil, farmers are advised to adopt farmyard manure (FYM) and ZnSO4 application.