In order to feed the world’s population, nitrogen consumption can certainly be increased locally

Excessive nitrogen consumption is a threat to nature worldwide, but regionally there is also room for more intensive use of nitrogen compounds in agriculture. For example, higher nitrogen fertilization is possible in sub-Saharan Africa, in Central and South America, and in Southeast Asia. This is also necessary to produce enough food for the growing world population. This is shown by Dutch researchers with a study that was published on Wednesday in Nature appeared.

More intensive fertilization with nitrogen compounds such as ammonia (NH3) in agriculture usually leads to higher food production, but excessive use is often at the expense of nature and drinking water quality. This is because more nitrogen is offered than the food crops can absorb. The nitrogen compounds then leach into the environment, causing soil acidification and toxic algae blooms. Many plant species accustomed to low amounts of available nitrogen disappear as they are outcompeted by a limited number of fast-growing species (such as nettles and tadpoles) that thrive in high concentrations of nitrogen. This problem occurs in many parts of the world, including the Netherlands.

In some parts of the world, the use of manure is still on the low side

In the past, groups of scientists have shown that a safe “planetary limit” has been exceeded: humanity would use about twice as much nitrogen as Earth can handle. But these scientists did not look enough at regional differences, say the researchers from Wageningen University and Research and the Netherlands Environmental Assessment Agency. Some ecosystems are less sensitive to excess nitrogen, while others are more vulnerable. And in some parts of the world, the use of nitrogen fertilizers is still on the low side.

The researchers describe a number of measures that can ensure that the world’s population can be fed without exceeding the nitrogen limits. The most important thing is a more efficient utilization of nitrogen. Agricultural sectors should produce the same amount of food with less nitrogen, for example through more targeted fertilization: less nitrogen input to plants that need little. Currently, on average, half of the nitrogen compounds in agriculture seep into the environment – ​​this should be reduced.

“You can also look at consumption patterns and food loss,” says Lena Schulte-Uebbing. She is an environmental researcher and first author of the study. With less overconsumption, food waste and a more plant-based diet in mainly the Western world, it is easier to stay within the nitrogen limits. In addition, nitrogen pollution from other sectors, such as traffic, can be reduced. And a redistribution of agriculture can be a solution: Less production in exposed areas, and more where nature can handle it.

Very large rainfall surplus

“Where there is a very large rainfall surplus, the nitrogen in the water is diluted to such an extent that the concentrations do not quickly become very high,” explains Schulte-Uebbing. “This is the case, for example, in tropical areas in South America and Southeast Asia.” But in areas with less heavy rainfall, such as the Netherlands, the nitrogen is diluted less in the rainwater. The nitrogen concentrations are then higher.

With a better redistribution of agriculture, the safe limit of worldwide nitrogen consumption can be adjusted upwards, but humanity is still above it. Without displacement of emissions, up to 43 megatons per year could leak into the environment, the researchers say. That limit can be raised to 57 megatons if nitrogen consumption increases where possible. However, the current nitrogen surplus is still twice as large.

“I fully support the conclusions of this work,” says Nicolas Gruber. He is professor of environmental physics at the Technical University of Zurich. “The study is not directly about ‘raising’ a planetary boundary, but rather redefines it by deriving it from regional nitrogen boundaries. This is logical as a nitrogen surplus is mainly a local to regional problem. It also seems reasonable to me to increase nitrogen consumption where it does not harm the environment unnecessarily. It’s a careful and deliberate approach to solving a dual challenge: feeding the world without polluting the world with nitrogen.”

Leave a Comment