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

This experiment was conducted at five on-farm locations each at Samastipur and Muzaffarpur Districts of Bihar and one plot at the University Research Farm, Rajendra Agricultural University in Pusa, Samastipur, Bihar, under hybrid rice-maize cropping system during 2013-14. Nine treatment combinations included: T1 (NPKSZn), T2 (-N), T3 (-P), T4 (-K), T5 (-S), T6 (-Zn), T7 (unfertilized local variety), T8 (local variety with ample NPKSZn), T9 (unfertilized hybrid variety). In hybrid rice (Var. Arize 6444), fertilizer was applied by fixing the target yield at 7 t/ha (175-70-80 kg N-P₂O₅-K₂O/ha) and in local rice (Rajshree) at 5 t/ha (125-50-60 kg N-P₂O₅-K₂O/ha). In hybrid maize (Var DKC 9081), fertilizers were applied based on a yield target of 10 t/ha (210-140-200 kg N-P₂O₅-K₂O/ha) and in local maize (Laxmi) at a yield target of 6 t/ha (150-70-120 kg N-P₂O₅-K₂O/ha). Sulfur was applied at 30 kg/ha as bentonite-S and Zn was applied as 25 kg Zn-EDTA/ha in both rice and maize.

Grain yields of rice and maize generally decreased with the omissions of nutrients. The grain yield of hybrid rice (Arize-6444) and local rice (Rajshree) varied from 4.1 to 6.8 t/ha and 2.5 to 4.6 t/ha under ample fertilized plot with NPKSZn. In general, maximum decline in rice grain yield was recorded for N followed by the P, K, S, and Zn omission plots. Under the unfertilized check, hybrid and local rice grain yield declined by 49 and 45% over the amply fertilized plots. The grain yield of hybrid maize (DKC-9081) and local maize (Laxmi) varied from 8.3 to 9.9 t/ha and 4.1 to 5.6 t/ha under amply fertilized plot with NPKSZn. The decline in maize grain yield was highest with N omission followed by P, K, S, and Zn. Due to omission of N, P, K, S, and Zn, the mean grain yield of hybrid maize declined by 43, 12, 9, 7, and 6% over the ample dose of NPKSZn. Under the unfertilized check, the hybrid and local maize grain yield (mean) declined by 48 and 46% over the ample NPKSZn fertilized plots. Ample application of NPKSZn not only improved the yield, but also improved the available nutrient status in soil.