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

The study was conducted at farmers' fields across two different districts (Samastipur and Muzaffarpur) of Bihar to refine fertilizer recommendations for rice and maize. The nine treatments included T1 (ample nitrogen (N), phosphorus (P), potassium (K), sulfur (S), and zinc (Zn)), T2 (-N), T3 (-P), T4 (-K), T5 (-S), T6 (-Zn), T7 (inbred variety under unfertilized check), T8 (inbred variety with ample NPKSZn), and T9 (hybrid variety under unfertilized check) within a randomized block. In hybrid rice (Arize 6444), the fertilizer (N, P₂O₅, K₂O) was applied at the rate of 175, 70, and 80 kg/ha by fixing the target yield at 7 t/ha. With the inbred rice variety (Rajshree), doses of N, P₂O₅, K₂O were fixed at 125, 50, and 60 kg/ha for a yield target of 5 t/ha. In hybrid maize (DKC9081), N, P₂O₅, K₂O were applied at the rate of 210-140-200 kg/ha for the yield target of 10 t/ha; while for the local variety (Laxmi), N, P₂O₅, K₂O were applied at the rate of 150-70-120 kg/ha for yield target of 6 t/ha.

At the different locations, grain yield of hybrid rice varied from 2.2 to 3.9, and 5.4 to 6.8 t/ha in the control (no fertilizer) and the ample application treatments, respectively. Nitrogen was the most limiting nutrient followed by P, K, S, and Zn. Average hybrid rice grain yield decrease due to N, P, K, S, and Zn omissions and absolute control were 40, 16, 12, 9, 7, and 55%, respectively, over the ample fertilization treatment. Grain yield of inbred rice (cv. Rajshree) ranged from 2.0 to 2.6 and 3.4 to 4.8 t/ha in control and ample fertilization treatment respectively, at different locations.

Grain yield of hybrid maize (cv. DKC 9081) varied from 1.4 to 2.8 for the control (no fertilizer) and 7.9 to 9.9 t/ha with ample dose of all nutrients at different locations. In general, the average hybrid maize grain yield decrease was more pronounced in N omission, followed by P, K, S, and Zn omissions. Average hybrid maize grain yield decrease due to N, P, K, S, and Zn omissions and absolute control were 69, 28, 23, 15, 16, and 81%, respectively, over the ample fertilizer application treatment. Grain yield of inbred maize (cv. Laxmi) ranged from 1.1 to 2.1 for the control and 4.9 to 6.0 t/ha in ample fertilizer treatment, respectively, at different locations. Grain yield of inbred maize dropped by 76% over ample fertilization treatment when no fertilizer was applied.