6 - Nitrogen Balances of Intensively Cultivated Rice–Wheat Cropping Systems in Original Green Revolution States of India

Abstract

Pre-green revolution period in India was characterized by low productivity, lack of inorganic fertilizer use, and dependence on animal manure and biological nitrogen fixation as sources of nitrogen. Introduction of high-yielding varieties of rice and wheat during the 1960s and 1970s, in the states of Punjab, Haryana, and western Uttar Pradesh, coupled with rapid growth in inputs, such as chemical fertilizers, irrigation, agrochemicals for pest and weed control, mechanized farming, and intensity of cropping, revolutionized the cereal production that came to be known as the “Green Revolution.” The food-grain production, in India, which was only 82million tons (mt) in the late 1960s increased to 264mt in 2013/14 making it self-sufficient in food production. Fertilizer-N use in the country increased largely with increase in the original green revolution states. In Punjab and Haryana, fertilizer-N use increased from meager 2–8kgNha−1 in 1960s to 160–180kgNha−1 till date compared to the national average of 82kgNha−1. In the backdrop of declining fertilizer-N efficiency of food-grain production, temporal trends of production factors in original green revolution states of India vis-à-vis whole country are presented in this chapter. Magnitude and flux of reactive nitrogen in intensive rice–wheat systems at the field and regional scale are discussed, and constraints to sustainability of agricultural production and the scenario for future are underpinned.