eng Enviro Research Publishers Current Agriculture Research Journal 2347-4688 2321-9971 2025-04-30 13 1 281 292 24059 article Mukesh Kumar Sharma 1 Manoj Khediya 1 Chetan Bhatt 2 Department of Instrumentation and Control of Vishwakarma Government Engg College, Gujarat Technological University, Ahmedabad, India Principal, Government MCA College, Gujarat Technological University, Ahmedabad, India The agriculture industry faces the challenges due to uncertainty, including unpredictable weather, rainfall, and improper crop and soil selection. Precision agriculture (PA) has mitigated these issues by monitoring and responding to crop variability. This paper offers the FertiCal-P App, an Android-based fertilizer calculator that recommends the NPK fertilizer requirements based on soil test data, such as N, P₂O₅, K₂O, and pH, to optimize crop yields and illustrate precision agriculture practices. The FertiCal-P App is developed using rule based and regression techniques and it calculates three different fertilizer recommendations, which are combinations of three chemical fertilizers out of five in two stages: the first at sowing and the second after 30 days of sowing, which ensuring optimal fertilizer efficiency, reduced fertilizer usage, lower cost and ultimately adverse impact on environment. The app's last screen indicates price breakups, which assist farmers in reaching financial and agronomical decisions. Further, we will need to test this approach at the district level in Gujarat prior tt rolling out it across the Indian sub continent. https://www.agriculturejournal.org/volume13number1/fertical-p-an-android-based-decision-support-system-dss-determines-the-npk-fertilizer-recommendation-by-assessing-ph-and-macronutrient-of-the-soil/ Chemical Fertilizer; Fuzzy Rule; Precision Agriculture; Regression; Soil Fertility