Nitrogen Fertilizers and Enviromental Problems
Nitrogen fertilizers enable farmers to achieve the high yields that drive modern agriculture. The use of nitrogen fertilizer will continue to increase substantially as global population and food requirements grow. International Fertilizer Industry Association (IFA) forecasts suggest that under current conditions nitrogen fertilizer applications will total nearly 100 million tons per year by 2010-11.
While fertilizers are effective in driving crop yield improvements, they also frequently have a negative impact on the environment. Since most plants are able to utilize less than one-half of the nitrogen fertilizer applied by growers, much of the remaining nitrogen fertilizer leaches into the air, soil and water and pollutes lakes, rivers, aquifers and oceans.
A significant portion of the unabsorbed nitrogen fertilizer volatizes in the form of N2O. In fact, agriculture is the second largest industrial contributor to global greenhouse gases (GHGs) -- ahead of the transportation sector and behind only electrical and heat generation. It is estimated that nitrogen fertilizer accounts for one-third of the GHGs produced by agriculture (Stern Review 2006).
One of the most visible examples of the harmful environmental effects of nitrogen fertilizers is the creation of "dead zones" in the world's oceans. Dead zones result from the death and decomposition of massive algae blooms that are fed by excessive nutrient runoff. When algae populations get too large, they die and their natural decomposition depletes the water of oxygen. This creates a condition called "hypoxia" and results in suffocation and death of fish species.
A 2004 United Nations Environment Programme report identified dead zones as one of the most significant global environmental threats facing the world. According to the report there are more than 146 dead zones around the world that range in size from between one square kilometer to more than 70,000 square kilometers.