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Abstract - Procedia Engineering, 2012

The number of undernourished people in the world remains unacceptably high at about 925 million. Global food security issues exist now, and are especially of concern looking forward as world population is expected to increase by about 35% over the next 40 years. Agricultural output will need to significantly increase to accommodate the growing population. Most of the increase is expected to come from producing more on existing farmland (i.e., intensification), although some new farmland will likely be needed. Boosting crop yields and closing the gap between actual and attainable yield can be achieved by the implementation and advancement of numerous practices and technologies, including nutrient management practices and fertilizer technologies. An evaluation of long-term studies has shown that the average percent of yield attributable to fertilizer inputs generally ranged from about 40 to 60% in temperate climates (USA and England), and tended to be much higher in the tropics. All things considered, inorganic fertilizer plays a critical role in world food security, but it must be recognized that highest yields are in some systems the result of using both organic and inorganic nutrient sources. Adoption of the 4R principles-right nutrient source at the right rate, right time, and right place-help ensure appropriate use of nutrient resources and optimized productivity.