Home Science The terrible environmental toll of artificial fertilizers and how to offset it

The terrible environmental toll of artificial fertilizers and how to offset it

The terrible environmental toll of artificial fertilizers and how to offset it

The use of chemical fertilizers has quadrupled the human population in the last century, but their use is destroying the environment.

Reducing nitrogen pollution from farmland around the world is a “big challenge”, say a group of international researchers in a study published in Nature in which a dozen of necessary and urgent reforms are outlined.

The intensive use of chemical fertilizers is the breakthrough that allowed the human population to quadruple in the last century and will be crucial to feed 10 billion people in 2050. But the bountiful harvests of what was once called the Green Revolution came at a terrible cost.

Nowadays, more than half of the nitrogen in fertilizers seeps into the air and water, causing deadly pollutionsoil acidification, climate change, depletion of the ozone layer and loss of biodiversity.

“Given the multiple repercussions of reactive nitrogen on health, the climate and the environment, it should be reduced in all media such as air and water,” said Baojing Gu, lead author and professor at Zhejiang University. The benefits of doing so far outweigh the costs, he added.

nitrogen cycle

The world is flooded with nitrogen, an essential element for the survival of all living beings, especially plants. Nearly 80% of the Earth’s atmosphere is nitrogen, although in gaseous form (N2) of little direct use to most organisms. This nitrogen is made available to plants when microbes living on them or in the soil convert it to ammonia through biological nitrogen fixation.

This process funnels around 200 million metric tons of nitrogen each year into the soil and oceans. Various forms of nitrogen end up being transformed and returned to the atmosphere with the help of bacteria, mainly in wetlands, after infiltration into the oceans or burning.

But this natural “nitrogen cycle” has been completely disrupted by the use of about 120 million tons of chemical fertilizers per year, according to the study. Less than half of that amount is taken up by plants and the rest seeps into the environment, causing a host of problems.

Gu-led researchers analyzed more than 1,500 field observations on farmland around the world and identified 11 key measures to reduce nitrogen losses and increase crop yields.

One of them is crop rotation, which consists of planting several crops on the same land to optimize the flow of nutrients in the soil. The benefits of reducing agricultural nitrogen pollution are about 25 times greater than the implementation costs, which amount to about $34 billion.

For China and India (whose extensive and intensive use of fertilizers makes them the world’s top nitrogen polluters), that cost would be around $5 billion and $3 billion, respectively.

Nearly half a trillion dollars in avoided costs is split between reducing premature deaths from air pollution, less damage to ecosystem services and increasing crop yields.

Despite its enormous benefits, advanced nitrogen management has upfront costs that many smallholders would not be able to afford without strong government policy support. A nitrogen credit system, for example, could subsidize farmers who adopt advanced nitrogen management techniques, reaping the economic benefits of reduced nitrogen pollution and increased food supplies.

To start this virtuous circle, a financial budget could be secured by taxing food consumers or companies that use agriculture for commercial food production, or by taxing polluting activities and products, according to the researchers’ proposal.

REFERENCE

Economic Mitigation of Nitrogen Pollution from Global Agricultural Lands

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