Effect of crop intensification on productivity, profitability, energetics and soil fertility in rice (Oryza sativa)-wheat (Triticum aestivum) cropping system of north-western plains

A field experiment was conducted during 1996-2000 at Karnal with 7 wheat (T riticum aestivum L. emend. Fiori & Paol.)-based crop sequences to intensify the rice (Oryza sativa L.)-wheat system by introducing short-duration and/ or green-manuring crops for enhancing the productivity and profitability on sustainable basis. After 4 years of study, rice-potato (Solarium tuberosum L.)-wheat-green-manure rotation recorded the maximum equivalent wheat yiel d, energy input and output, gross return and total cost of cultivation. The organic carbon and available soil N contents were also higher than the oth er crop sequences, but the benefit: cost ratio was the lowest under this se quence. On the other hand, growing of vegetable pea (Pisum sativum L.) betw een rice and wheat gave the maximum net return (Rs 42 512/ha), energy outpu t : input ratio (3.36) and build-up soil fertility level similar to rice-wh eat-green-manure rotation. Incorporation of prickly sesban or dhaincha [Ses bania cannabina,(Retz.) Pers.] continuous for 4 years and growing of vegeta ble pea and potato between rice and wheat increased 8.7, 8.9 and 17.1 % org anic carbon; 12.1, 6.3 and 8.3 % available N and 10.1, 6.3 and 19.0 % avail able P respectively compared with rice-wheat system.