Effect of Soil Test Crop Response (STCR) and STCR –Integrated Plant Nutrition System (IPNS) Based Fertilizer Prescription Equations on Maize Productivity, Economics and Soil Fertility Status in Vertisols of Northern Karnataka

A study on Soil Test Crop Response based Integrated Plant Nutrition System (STCR - IPNS) was conducted adopting an Inductive cum Targeted yield model in vertisols of Northern Karnataka at Main Agricultural Research Station (MARS), UAS, Dharwad, Karnataka during kharif 2020-21 in order to develop STCR and STCR-IPNS fertilizer prescription equations (FPEs) for achieving desired yield targets of maize. Fertilizer doses at varying soil test values, for attaining 60, 80 and 100 q ha-1 target grain yield of maize have been worked out based on the initial soil test values of available N, P and K and the quantities of N, P and K added through farm yard manure (FYM). Using these equations, validation trials were conducted during kharif 2021-22 at MARS, Dharwad and Irrigation Water Management Research Centre (IWMRC), Belavatgi. The results of the experiment indicated that at both the locations, the per cent achievement of the targeted yield was within ± 10 % variation proving the validity of the equations for prescribing integrated fertilizer doses for maize. The highest grain yield was recorded in STCR-IPNS equation with 100 q ha-1 target yield (Dharwad -104.8 q ha-1, Belavatgi – 102.3 q ha-1) recording an increase of 67 and 69 per cent over recommended package of practices at Dharwad and Belavatgi, respectively. However, it was found to be on par with Jabalpur STCR equation with 100 q ha-1 target yield and STCR-NPK alone equation with 100 q ha-1 target yield. Higher gross returns were recorded under STCR-IPNS equation with 100 q ha-1 target yield owing to higher grain and stover yields. While STCR equation developed at Jabalpur with 100 q ha-1 target yield recorded higher net returns. The post-harvest soil available NPK indicated better build-up and maintenance of soil fertility by the soil test based fertilizer recommendation under IPNS. Targeting 100 q ha-1 grain yield for maize under STCR approach was found to be ideal in terms of yield, economics and soil fertility maintenance in vertisols of Karnataka. The fertilizer prescription equations developed for maize under IPNS can be recommended for vertisols of Northern Karnataka for achieving target yield of 100 q ha-1 with sustained soil fertility and it can be extrapolated to other agro-climatic zones of Karnataka on similar and allied soil types.