Tailoring Soil Test Based Fertilizer Doses to Obtain Higher Wheat Yield

The wheat growing fields of north Karnataka were non-saline (ECe < 4 dSm-1) and pH of these soils was buffered at 8.4. Most of the fields were low in organic carbon content. Among major nutrients, Nitrogen was the most deficient with the average available nitrogen status of 148 kg ha-1. The available phosphorus was rated as medium to high and available potassium was very high. Among the micronutrients, Fe, Zn and Cu were deficient in the wheat soils whereas, Mn available status was rated high. The grain yield remained significantly higher under STCR fertilizer dose that had 190:89:91 kg ha-1 N, P2O5 and K2O, respectively compared to recommended fertilizer dose (100:75:50 kg ha-1 N, P2O5 and K2O, respectively) under LMH category of soil test values. Under the LML category of the soil fertility status, STCR dose (178:100:135 kg ha-1 N, P2O5 and K2O, respectively) registered the highest grain (29.2 q ha-1) and straw yield (49.2 q ha-1) of the crop. This treatment was significantly higher compared to all other treatments except the dose that was modified by -+ 25 per cent for nitrogen and potassium which were low in soil (125:75:62 kg ha-1 N, P2O5 and K2O, respectively). Similarly, STCR (200:89:103 kg ha-1 N, P2O5 and K2O, respectively) and + 50 per cent modified fertilizer dose (150:56:25 kg ha-1 N, P2O5 and K2O, respectively) recorded higher grain and straw yields compared to the RDF under LHH category of soil nutrient status category. Fertilizer use efficiency remained the least and significantly lower in STCR dose compared to all other soil test based doses.