Diversification of rice (Oryza sativa)–wheat (Triticum aestivum) cropping system for sustainable production in south Bihar alluvial plains
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A field experiment was conducted during 2009–10 to 2011–12 at Sabour, Bhagalpur, Bihar to diversify the existing rice (Oryza sativa L.)–wheat [Triticum aestivum (L.) emend. Fiori & Paol.] cropping system. Among the 12 rice-based cropping systems tested, scented rice–potato (Solanum tuberosum L.) + radish (Raphanus sativus L.)–onion (Allium cepa L.) + maize (Zea mays L.) relay cropping gave the highest mean rice-equivalent yield (28.10 t/ha/year) and net returns ( 1,14,700/ha/year), followed by hybrid rice–maize + potato–sorghum [Sorghum bicolour (L.) Moench] + cowpea [Vigna unguiculata (L.) Walp.] both grown for fodder (24.2 t/ha/year and 1,12,200/ha/year) and hybrid rice–garlic (Allium sativum L.) + coriander (Coriandrum sativum L.)–maize for grain purpose + cowpea in-situ incorporation (22.60 t/ha/year and 1,11,600/ha/day). However, the benefit: cost ratio was the highest (1.39) in long-duration rice–wheat–mungbean [Vigna radiata (L.) Wilczek] both sown by zero till, which was at par with scented rice–wheat + fenugreek (Trigonella foenum-graecum L.)–mungbean grown for grain + residue incorporation (1.37). Scented rice–potato + radish–onion + maize relay cropping required higher energy inputs (69.35 MJ × 103/ha), whereas energy-use efficiency was the maximum (5.0) in rice–maize (ZT)–clusterbean [Cyamopsis tetragonoloba (L.) Taub.] (fodder). Hybrid rice–maize + potato–sorghum + cowpea showed the highest energy output (287.01 MJ × 103/ha) and water-use efficiency (36.6 kg rice-equivalent yield/ha-mm). This cropping system removed the maximum quantity of N (448.4 kg/ha), P (130 kg/ha) and K (457.2 kg/ha) which resulted in maximum negative balance of phosphorus (32.8 kg/ha) and potassium (320.2 kg/ha). Potassium was negative in all the cropping systems, indicating that K was the most removable nutrient by the crops, which results in mining of soil K and thus calls for adequate fertilization.
Diversification, Economics, Nutrient balance, Rice-equivalent yield, Rice–wheat cropping system productivity.