Nutrient use efficiency based standardization of macronutrient requirement in direct seeded rice

Field experiments were conducted during the kharif seasons of 2019 and 2020 using a factorial randomized block design. The experiment included three levels of NPK nutrients and three application timings as the first and second factors, respectively, to determine the optimal NPK requirement and timing based on nutrient use efficiency. Experimental results revealed that the application of 125:62.5:62.5 kg ha−1 of N:P2O5:K2O (F3) resulted in higher growth and yield parameters, along with increased grain yield and total nutrient uptake. Among the nutrient application timings, T3 (25% N and K + 100% P as basal, 25% N and K at 20–25 DAS, 25% N and K at 40–45 DAS, and 25% N and K at 55–60 DAS) outperformed the other schedules. Even though the application of 125:62.5:62.5 kg ha−1 of N:P2O5:K2O (F3) resulted in higher agronomic efficiency (16.42, 32.83, and 32.83 kg kg−1), apparent recovery efficiency (39.47, 14.63, and 88.23%), nutrient requirement (1.930, 0.325, and 2.079 kg q−1) for nitrogen, phosphorus, and potassium, respectively, and a response yardstick of 8.208 kg kg−1, it may not have been the most economical treatment. However, a higher yield response (2052 kg ha−1) was observed with the application of 100:50:50 kg ha−1 of N:P2O5:K2O (F2). Among the nutrient application timings, T3 recorded higher partial factor productivity (51.14, 102.27, and 102.27, respectively), yield response (1193 kg ha−1), and response yardstick (5.963 kg kg−1) compared to the other two timings and the farmer’s practice.