Geographical Information System based spatial fertilizer recommendation mapping using soil test crop response equations and validation in paddy

The main barrier to greater crop output is unpredictability of soil nutrients. It’s necessary to produce location-specific information on status of soil nutrients. This study aimed to develop and validate Geographical Information System (GIS)-based spatial fertilizer recommendation maps using Soil Test Crop Response (STCR) equations for improving rice yield and nutrient management in the command area. The nutrients used to achieve the intended yield are significantly reduced by STCR equation integrated with fertiliser recommendation maps. Gathered 59 composite soil samples in the Hosahalli village tank command area of Hassan district, Karnataka (India) and plotted the nutrient recommendations for desired yields in GIS platform. The interpolation technique was used to create the ready reckoner nutrient tables and nutrient recommendation maps for rice production. Executed a field experiment in farmer's fields of command area in kharif 2021 based on the recommended maps to achieve the targeted yields of 40, 50 and 60 q ha-1 compared with farmer's practice at different organic carbon levels. The study area was acidic, normal EC, low in OC and available P, moderate in available N and K. STCR fertilizer recommendation for 60 q ha-1 targeted yield has recorded higher grain and straw yields. The STCR fertilizer recommendation for 60 q ha-1 target yield increased grain yield by 68 % (53.59 q ha-1 compared to 31.89 q ha-1) and straw yield by 48 % (80.36 q ha-1 compared to 54.12 q ha-1) over farmer practice while reducing fertilizer usage. The rice growth, yield and nutrient uptake were significantly impacted by the fertiliser recommendations for targeted yields. The farmer's precise target yield was achieved with far less fertiliser owing to the thematic nutrient recommendation maps.