Development of Soil Test Crop Response (Stcr) and Stcr-Integrated Plant Nutrition Supply (Ipns) Models to Achieve Targeted Yields of Maize (Zea mays L.) in Vertisols of Northern Karnataka

Background: Soil test crop response (STCR) approach assists in determining the appropriate amount of fertilizer to use for particular season and location based on the initial soil fertility status and crop response in terms of nutrient uptake and yield. A field experiment was conducted during 2020-21 at Dharwad, by adopting the Inductive Cum Targeted Yield Model to develop soil test-based fertilizer prescriptions under STCR and STCR-IPNS approach to achieve desired target yields of maize in vertisols of Northern Karnataka, India. Methods: In the experiment’s first phase, an exhaust crop fodder maize was grown in three different fertility strips. After the harvest of fodder maize, the soil fertility levels varied significantly among the strips, indicating the creation of fertility gradients. In the second phase of the experiment, a test crop (hybrid maize) was grown and the response of maize to four levels of N, P and K and three levels of FYM under different fertility gradients was studied. The basic parameters viz, nutrient requirement (NR), contribution of nutrients from soil (Cs), fertilizers (Cf) and FYM (Cfym) were computed using the data from test crop experiment. The basic parameters viz, nutrient requirement (NR), contribution of nutrients from soil (Cs), fertilizers (Cf) and FYM (Cfym) were computed using the data from test crop experiment. Result: Using the basic parameters, fertilizer prescription equations for desired yield targets of maize under NPK fertilizers alone and under STCR-IPNS (with FYM) were derived based on initial soil test values. Results of the validation experiment in kharif 2021 revealed that the grain yield was significantly higher under STCR-IPNS equation with a target yield of 100 q ha-1 as compared to other treatments. STCR-IPNS equation with the application of FYM to achieve 100 q ha-1 target yield resulted in savings of 11, 10 and 15 percent of N, P2O5 and K2O as compared to STCR-NPK alone equation.