Influence of balanced fertilization on productivity and nutrient use efficiency of cereal based cropping systems

Increasing the use efficiency of nitrogen in system mode was always a concern due to escalating input cost of fertilizer. The "researcher designed farmer managed trials" were conducted in farmers' field during 2009-10 at 27 districts covering 17 states. A total of 192 trials in rice-rice, 233 in rice (Oryza sativa L.)-wheat (Triticum aestivum L.), 48 in rice-greengram and 77 in maize-wheat system were conducted with five common treatments, viz. control, recommended quantity of N alone, NP, NK and NPK in all the locations and cropping systems. Application of recommended quantity of NPK in all the systems recorded higher yield and increase was found to be more than 50% in maize (Zea mays L.)-wheat and rice-rice systems and > 30% in rice-greengram [Vigna radiata (L.) Wilczek] and rice-wheat systems over application of N alone. On an average additional yield of 2 794 kg rice equivalent yield (REY)/ha was realized, in cereal based systems with application of all the nutrients together instead of N alone. Among the various systems, maize-wheat was found to respond well to balanced application as it recorded 162% increase in yield over control. Partial factor productivity (PFP) of N, can be increased by > 50% in rice-rice and maize-wheat system through application of recommended dose of NPK. Efficiency of applied nutrients measured in the form of agronomic efficiency was found to be >100% for all the systems under balanced application compared to N alone, or with P with K. Similarly combined application increased the P and K efficiency in all the systems with maize-wheat recording the highest efficiency of K. Relative response of treatment over control also displayed similar trend. Marginal returns due to application of NPK together was found to be 136.7, 24.5, 11.5 and 46.4% higher in rice-rice, rice-wheat, rice-greengram and maize-wheat systems respectively over application of N alone. Balanced application of N, P and K was found to increase the system productivity and nutrient use efficiency of cereal based systems.