Assessing the Contribution of Nutrients to Yield of Hybrid Rice and Maize through Omission Plot Techniques in Bihar

This study was designed to evaluate yeild response to nutrient additions in a hybrid rice-maize cropping system. Specific objectives of this study were to evaluate the soil supplying capacity of different nutrients (N, P, K, and Zn) under hybrid rice-maize cropping system and to determine the nutrient requirement of high yielding hybrid rice–hybrid maize cropping system. The experiment was started in the summer of 2013 in farmer fields as well as at the research farm of Rajendra Agricultural University, Pusa, Bihar. The following treatments were included in the experimental design: T1, an ample dose of N+P+K+S+Zn; T2, ample but without N; T3, ample but without P; T4, ample but without K; T5, ample but wihtout S; T6, ample but without Zn; T7, local crop variety with no added nutrients; T8, local crop variety with ample fertilizer; and T9, no fertilizer, but with plant protection measures. The ample N, P, K, S and Zn rates were determined based on crop's nutrient requirement for a predetermined yield target. Other deficient nutrients were considered for application as per site-specific requirements.

Initial observation shows that the grain yield of hybrid rice (cv. Arize 6444) varied from 2.0 to 3.4 t/ha in unfertilized control plots and from 4.1 to 6.8 t/ha in the NPK plots across different locations. Omission of nutrients reduced the yield, with N being the single most limiting element. The reduction in grain yields due to N, P, K, S, and Zn omissions varied from 34 to 42, 9 to 15, 7 to 8, 4 to 6 and 3 to 5%, respectively, over the ample fertilizer treatment plot. The grain yields dropped by 49 to 54% in control plots over the ample fertilization treatment. The varietal impact was also observed in the yields of local rice (cv. Rajshree) where grain harvest ranged from 1.6 to 2.4 and 2.8 to 4.6 t/ha in control and ample fertilization treatment plots, respectively, at different locations.