From: B. Rose Huber, Woodrow Wilson School of Public and International Affairs, Princeton University
Published November 30, 2015 11:33 AM

We need to use Nitrogen fertilizers more efficiently

The global population is expected to increase by two to three billion people by 2050, a projection raising serious concerns about sustainable development, biodiversity and food security, but new research led by Princeton University shows that more efficient use of nitrogen fertilizers may address both environmental issues and crop production.

Today, more than half of the world's population is nourished by food grown with fertilizers containing synthetic nitrogen, which is needed to produce high crop yields. Plants take the nitrogen they need to grow, and the excess is left in the ground, water and air. This results in significant emissions of nitrous oxide, a potent greenhouse and ozone-depleting gas, and other forms of nitrogen pollution, including chemical over-enrichment of lakes and rivers and contamination of drinking water. 

Given the world's growing food demands, nitrogen fertilizer use is likely to increase. Using too much fertilizer, however, will lead to increased pollution of waterways and the air. What's needed is a more efficient use of fertilizer, which will benefit both food production and the environment, according to a study published in Nature.

Led by Princeton, the paper is among the first to globally analyze "nitrogen use efficiency" — a measure of the amount of nitrogen a plant takes in to grow versus what is left behind as pollution. Looking at fertilizer and crop harvest data in regions like the United States, Western Europe and Sub-Saharan Africa, the researchers examined how policies and market conditions have influenced farmers' use of nitrogen fertilizers over the past five decades. 

Based on their findings, the researchers suggest specific nitrogen use targets based on region and crop type to meet 2050 global food-demand projections and environmental stewardship goals. Currently, the global average for nitrogen use efficiency is approximately .4, meaning 40 percent of the total nitrogen added to cropland goes into the harvested crop while 60 percent is lost to the environment. To reduce environmental impacts, the researchers urge an increase in global average nitrogen use efficiency to 70 percent so only 30 percent of the total nitrogen is lost to the environment. To achieve this goal, the researchers provide examples of specific targets in 2050 for various regions that take into account differences in ecological and socioeconomic conditions. 

These targets could be used in tandem with the United Nations' Sustainable Development Goals, the researchers write, which were released in September.

Fertilizer application image via Shutterstock.

Read more at Princeton Uninversity.

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