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Commercial organic and synthetic nitrogen fertilizer helps feed around half of the world's population. While excessive fertilizer use poses environmental and public health risks, many developing nations lack access to it, leading to food insecurity, social unrest and economic hardship.

A team of scientists, led by the University of California, Davis, has published a study that identifies five strategies to tackle the problem. These include applying fertilizers more precisely, getting nitrogen to where it's needed most, removing nitrogen pollution from the environment, reducing food waste and empowering consumers to think about sustainable food options.

"We have a two-sided challenge and we can't just focus on one side and forget about the other," said lead author Ben Houlton, professor and director of the John Muir Institute of the Environment at UC Davis. "People not having access to fertilizer to grow food is as much of a problem as inefficient use of it."

Too little

The cost of fertilizer is a major barrier in emerging market economies, particularly for farmers in sub-Saharan Africa and parts of Latin America. Government subsidies can help, but the research suggests the problem isn't just an economic one. Policies among governments need to be better coordinated to help farmers gain access to fertilizer, using the most advanced and sustainable precision-agricultural approaches.

A coordinated international policy is urgently needed, said Houlton. While groups like the International Nitrogen Initiative have made significant progress in advancing global nitrogen issues, the study calls for a formal research mandate similar to the United Nations' Intergovernmental Panel on Climate Change to solve the global nitrogen problem.

Too much

Feeding an expected 10 billion people by 2050 could increase fertilizer use by as much as 40 percent. Shifting fertilizer application practices will be key, said Houlton. Slow-release fertilizers, "fertigation" (fertilizers with irrigation water) and using new sensor technologies and drones can help improve nitrogen efficiency. These techniques can be costly, presenting challenges to adoption.

"Similar to offering consumers rebates for buying the first electric cars, we need incentives for farmers to adopt these practices," Houlton said.

The study also discusses ways to remove nitrogen pollution from the environment, including river and floodplain restoration projects and buffer strips designed to improve water quality.

Food waste and diet

One-quarter of all food produced is wasted. Its disposal at landfills also produces greenhouse gases such as methane and nitrous oxide. The research suggests repurposing food waste as animal feed or turning it into compost. The study also highlights the need for increasing consumer awareness to reduce overbuying.

Another strategy for reducing nitrogen overuse is to empower consumers to understand sustainable food growing practices and healthy food choices . Not all crops, dairy or meat is grown in the same way. The study suggests more research and life cycle assessments of how different growing practices affect nitrogen footprints so consumers can determine options that make the most sense for their particular culture and values.

"Nitrogen as a problem is quite solvable" Houlton said. "The benefits of a sustainable nitrogen balance can materialize remarkably quickly, from assisting in humanitarian crises to slashing global climate pollutants, preserving Earth's biodiversity, and reducing toxic algae blooms in rivers, lakes and the sea."

The study was published online today in the journal Earth's Future.

More information: Benjamin Z. Houlton et al, A World of Cobenefits: Solving the Global Nitrogen Challenge, Earth's Future (2019). Benjamin Z. Houlton et al, A World of Cobenefits: Solving the Global Nitrogen Challenge,(2019). DOI: 10.1029/2019EF001222