Farmers urged to switch to manure

By-products of nitrogen fertilizers are greenhouse gases, damage air quality

Environmental experts are calling on farmers across the globe to replace nitrogen fertilizers to reduce nitrogen pollution.

Although nitrogen is essential for achieving high crop yields, its abundant use has turned it into the dominant contributor to global nitrogen pollution, which poses substantial risks to climate, human health and ecosystems.

Nandula Raghuram, a professor at Guru Gobind Singh Indraprastha University in New Delhi, said nitrogen is going to be an important part of the larger move toward sustainable production and consumption.

"We need to produce and consume reactive nitrogen sustainably to improve the situation. Farmers should be encouraged to use organic manure instead of chemical fertilizers to reduce nitrogen pollution," he said.

Raghuram said municipal and local authorities can play a vital role in working with farmers to implement the national policy on reducing nitrogen pollution.

In addition to agriculture, the growing demand on the livestock, transport, industry, and energy sectors has led to a sharp growth of the levels of reactive nitrogen - ammonia, nitrate, nitric oxide (NO), and nitrous oxide (N2O) - in the ecosystem.

According to the newly released Frontiers 2018-19 report from the UN Environment Programme, nitrogen pollution has tremendous consequences. Besides emitting greenhouse gases, nitrogen compounds damage air quality and the ozone layer.

The report states that every year, an estimated $200 billion worth of reactive nitrogen is lost into the environment. Considering the whole food chain, only 20 percent of the reactive nitrogen added in farming ends up in human food. The remaining 80 percent is wasted as pollution and di-nitrogen (N2) to the environment.

The nitrogen-cutting message is also relevant for parts of the globe with little reactive nitrogen like sub-Saharan Africa. Reducing reactive nitrogen there would help nutrients to go further in supporting food production, the report stated.

Mark Sutton, a professor of the Centre for Ecology and Hydrology in Edinburgh, said there is an urgent need to bring nitrogen science and policies together across multiple threats.

"Ultimately, the question for the countries as they start to discuss the way forward is, will they continue with the existing fragmentation between policy areas?

"Do they want one of their policy areas to take the lead? Do they want the new nitrogen convention? Or is it a case of a coordination mechanism bringing together between those conventions? As scientists we brought all that on the table. It's now the job of the countries to give us their views," he said.

Joyce Msuya, acting executive director of the UN Environment Programme, said she appreciates that a holistic approach to the global challenge of nitrogen management is beginning to emerge.

"In China, India and the European Union, we are seeing promising new efforts to reduce losses and improve the efficiency of nitrogen fertilizers. Ultimately, the recovery and recycling of nitrogen, as well as other valuable nutrients and materials, can help us to farm cleanly and sustainably, a hallmark of a truly circular economy," Msuya said.

China, the world's top producer of rice and wheat, in 2015 set the goal of zero growth in the use of chemical fertilizer and pesticides by 2020, without reducing food production.

The next step for China is focusing on socioeconomic barriers associated with farm size, innovation and information transfer.

The circular economy package adopted by the EU in 2015 aims to maximize the efficiency of resource use in all steps of the value chain. The plan recognizes the management and trade of organic and waste-based fertilizers as key in the recovery and recycling of bio-nutrients such as nitrogen and phosphorus.

The new regulation encourages the sustainable and innovative production of organic fertilizers using domestically available bio-waste, animal by-products such as dried or digested manure, and other agricultural residues. Currently, only 5 percent of organic waste material is recycled and applied as fertilizer within the EU.

In India, a financial perspective informs the government's policy from 2016, requiring all urea fertilizer to be coated with neem oil, in order to reduce both environmental losses of reactive nitrogen and financial leakage of the subsidy to nonagricultural urea applications.

edithmutethya@chinadaily.com.cn

(China Daily 03/08/2019 page11)