Development of Soil Test based Fertilizer Prescription Equations under IPNS for Rice in Salt affected soils of Tamil Nadu

Abstract

Soil Test Crop Response - Integrated Plant Nutrition System (STCR - IPNS) technology in restoring soil fertility in sodic soil was well established in this study. STCR -IPNS correlation studies were conducted with rice in black calcareous sandy clay loam (Vertic Ustropept) sodic soils of Tamil Nadu, Southern India during 2019 – 2021and fertilizer prescription equations under Integrated Plant Nutrition System (IPNS) were developed. A ready reckoner of fertilizer doses at varying soil test values, for attaining 6 and 6.5 t ha-I target grain yield of rice has been worked out. Using these equations, test verification trials were conducted on farmer's holding in Manikandam block of Tiruchirapalli district. The per cent achievement of the targets aimed was more than 90 indicating the validity of the equations for prescribing fertilizer doses for rice under sodic soils. The STCR -IPNS treatments recorded relatively higher response ratio (RR) and benefit - cost ratio (BCR) over blanket, STCR - NPK alone treatments and farmer's practice. Post-harvest soil tests for NPK revealed that there was maintenance of soil fertility under sodic soil.