Improved Nitrogen Use Efficiency in Lowland Rice Fields for Food Security
The productivity of agricultural systems must improve substantially to support increasing populations without further conversion of wilderness into farmland. By 2050, it is estimated that 70% more food must be produced to feed an estimated global population of over 9 billion with changing food consumption patterns and preferences. Rice is the staple food of more than half of the world’s population. More than 90% of the world’s rice is grown in Asia where one-half of the world’s population and 80% of the world’s poor are concentrated. In Bangladesh, one of the most climate-vulnerable nations, farmers intensively cultivate rice on 80% of agricultural lands. With the increasing population growth rate, it is estimated that the demand for rice will be 56% higher by 2050 than in 2001. Therefore, rice productivity should be increased to meet the food demand of a growing population, taking into account the dwindling amount of land area available for farming. This requires judicious use of agricultural inputs, including quality seeds and fertilizers, and water management, among other good agricultural practices. Fertilizer use has played a crucial role in meeting the food demand of a growing world population. Among the fertilizers, nitrogen (N) fertilizer is the main driving force to produce large rice yields under irrigated and favorable rain-fed conditions. Farmers usually apply urea as a broadcast method. Much research conducted across countries reported that more than 50% of applied nitrogen is not utilized by crops and lost to the environment as reactive forms (ammonia, nitrate, nitrogen oxides) through volatilization or surface water runoff, contributing to greenhouse gas emissions and other environmental problems such as eutrophication and groundwater pollution. This also results in higher costs for farmers given that N fertilizers generally represent over 10-15% of crop production costs. Therefore, fertilizer management should consider the 4R concept – right methods, right time, right rates, and right sources to increase use efficiency, crop yield, soil health, and farm profits and to reduce negative environmental effects.