ABSTRACT
Sequential cropping of rice and wheat on the same field came into prominence in the irrigated Indo-Gangetic Plains (IGPs) of India after the mid-1960s to provide food security to a burgeoning population. Since then it has occupied a dominant place in livelihood gathering, employment generation, poverty alleviation, and environmental impacts. Rice (Oryza sativ L.) and wheat (Triticum aestivum L.) constituted more than 75% of the total food grain production of India during the past five years. The majority of the 10.5 million ha under the rice-wheat system of India (Woodhead et aI., 1994) is concentrated in Punjab, Haryana, Western Uttar Pradesh, the Tarai region of Uttaranchal, Bihar, and West Bengal. The total area of 13.5 mba of India, Pakistan, Bangladesh, and Nepal account for 25% of the rice and 33% of the wheat production in the South Asian region (Ladha et aI., 2000). About 32% of the total rice and 42% of the total wheat area of South Asia is seeded in the rice-wheat system (Hobbs and Morris, 1996).
