Diversification of rice (Oryza sativa)-wheat (Triticum aestivum) system for improving soil fertility and productivity

A field experiment was conducted during 1996–97 to 1999–2000 at Karnal, to evaluate the effect of 6 rice (Oryza sativa L)-based crop sequences on soil fertility and productivity. Maximum wheat-equivalent yield was recorded by inclusion of potato (Solanum tuberosum L.) (197.1–200.3 q/ha), followed by vegetable pea (Pisum sativum L.) (173.5–173.8 q/ha) between rice and wheat (Triticum aestivum L emend. Fiori & Paol.) crops. These systems resulted in additional wheat-equivalent yield of 48–71 q/ha over the rice-wheat system. Continuous incorporation of Sesbania aculeata as green-manure increased organic carbon by 8.7%, available N by 12.1%, Olsen's P by 10.1% and available K by 5.0% in soil compared to rice-wheat sequence. Growing of vegetable pea and potato between rice and wheat also increased organic carbon by 8.9 and 17.1%, available N by 6.3 and 8.3% and available P by 6.3 and 19.0%, respectively, compared to rice-wheat system. Green-manuring with Sesbania aculeata added 97–109 kg N/ha and enhanced the wheat-equivalent yield in the rice-wheat system. Electrical conductivity and pH of soil decreased due to the inclusion of vegetable rice, potato and green-manure.