Need for determining ecofriendly optimum fertilizer nitrogen level for better environment and for alleviating hunger and malnutrition

摘要

Asia accounts for about two-thirds of hungry and malnourished people in the world and within Asia, South Asia, which includes India, Pakistan and Bangladesh accounts for about 34.3%, which in absolute numbers are 276.4 million people. Cereals are thestaple food in Asia and alleviation of hunger aims at increasing the availability of cereals (rice, wheat, maize etc.) in these countries. It is estimated that without fertilizer nitrogen about half of the world population would have remained hungry andmalnourished. However, excess fertilizer nitrogen is detrimental to the environment. Ammonia volatilized from surface applied fertilizer nitrogen reduces air quality, while nitrous oxide is a powerful greenhouse gas contributing to global warming and isalso responsible for depletion of atmospheric ozone. Excessive nitrogen fertilizer is reported to increase nitrate concentration in drinking water leading to blue baby syndrome or methaemoglobinemia, while eutrophication of surface water is responsible to mortality of fish and other sea creatures. Therefore, efforts are underway to increase the efficiency of fertilizer nitrogen by using 4Rs, namely, right source applied at the right rate, time and depth. A number of studies have indicated that it is possible to obtain the desired production of cereals with much lesser nitrogen rates and it is suggested to shift from economic optimum rate (Ecol_(opt)) to ecological optimum rate (Ecol_(opt)) rate of nitrogen application to cereals in making out fertilizer recommendations. This exercise has not yet been done by the agronomists in India and is strongly recommended.