Nitrogen use efficiency, an indicator that describes how much fertilizer reaches a harvested crop, has decreased by 22 percent since 1961, according to new findings by an international group of researchers who compared and averaged global data sets.

Excess nitrogen from fertilizer and manure pollutes water and air, eats away ozone in the atmosphere and harms plants and animals. Excess nitrogen can also react to become nitrous oxide, a greenhouse gas 300 times more potent than carbon dioxide.

Significant disagreements remain about the exact value of nitrogen use efficiency, but current estimates are used by governments and in international negotiations to regulate agricultural pollution.

"If we don’t deal with our nitrogen challenge, then dealing with pretty much any other environmental or human health challenge becomes significantly harder," David Kanter, an environmental scientist at New York University and vice-chair of the International Nitrogen Initiative, told New Scientist in May. Sri Lanka and the United Nations Environment Programme called for countries to halve nitrogen waste by 2030 in the Colombo Declaration.

Whereas the global average shows a decline, nitrogen fertilizing has become more efficient in developed economies thanks to technologies and regulations, and new results out last month from the University of Minnesota as well as field trials by the International Fertilizer Development Center are just two examples of ongoing research to limit nitrogen pollution without jeopardizing yield.

Read the full article about nitrogen by Jenessa Duncombe at GreenBiz.