Productivity, profitability and nutrient balance as influenced by diversification of Eice (Oryza sativa)-wheat (Triticum aestivum) cropping system

Abstract

A field experiment was conducted during 2004-2005 and 2005-06 at Sabour, Bihar to diversify the existing rice (Oryza sativa L.) A wheat (Triticum aestivum L. emend. Fiori & Paol.) cropping system. Among the 14 rice-based cropping systems tested, rice-potato (Solanum tuberosum L.)Aonion (Allium cepa L.) + maize (Zea mays L.) relay cropping gave the highest mean rice-equivalent yield (30.66 tihdyear), followed by rice-garlic (Allium sativum L.) - maize (30.35 tihalyear) and rice-potato-onion (27.95 tihdyear). The highest net returns of R s 96,581lhdyear were realized from rice-garlic-maize, which were on a par with that of rice-potato-onion + maize relay cropping (Rs 92,837lhalyear). However, the benefit : cost ratio was highest (1.73) in rice-berseem [Trifolium alexandrinum (L.) Juslen.] ii maize + cowpea [Vigna unguiculata (L.) Walp.], both grown for fodder. The highest water-use efficiency (37.01 kg rice-equivalent yieldlhdmm) was recorded with riceRgarlicAmaize system. The rice-potato-onion + maize relay cropping proved the most effective in producing highest calorific value (61,155 K calorieslha) and showed the maximum land-use efficiency (94.8%). The same cropping system removed the maximum quantity of N (371.6 kglha), P (1 10.4 kglha) and K (451.4 kg1 ha), followed by rice-berseem -maize + cowpea (F), having cor- responding values 352.0, 88.2 and 361.0 kg/ hdyear. Heavy removal of NPK by rice-berseem-maize+cowpea (F) resulted in maximum negative balance of nitrogen (1 52.9 kglha), phosphorus (31.4 kglha) and potassium (304.6 kglhalyear). Potassium balance was negative in all the cropping systems, indicating that K was the most remov- able nutrient by the crops, which results in mining of soil K and thus calls for adequate K fertilization.