SDGs ‘ignore threat of fertiliser overuse’

Fertilising Field_G.M.B. Akash_Panos
Copyright: G.M.B. Akash/Panos

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  • Fertiliser use may rise to meet goals related to hunger and food security
  • Overuse harms water supplies and the health of aquatic ecosystems
  • But agreeing legal limits on phosphorus and nitrogen use could be tricky

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The Sustainable Development Goals (SDGs) fail to address one of the planet’s most urgent environmental problems: changes in soil nitrogen and phosphorous cycles, a meeting on the goals has heard.

This oversight could scupper the success of the majority of the SDGs, said Dann Sklarew, an environmental scientist from George Mason University, United States.

The use of phosphorus and nitrogen to fertilise fields is expected to be exacerbated by the increased food production required to meet the proposed SDG 2, which targets hunger, food security and nutrition, the event heard. This could cross ‘planetary boundaries’ related to the health of the earth’s soil and water systems, delegates were told.

“As well as thinking of the climate as a crisis, we also need to think of the nitrogen and phosphorous cycles as a crisis,” Sklarew told the meeting, which took place on 18 March at US think-tank the Wilson Center.

“We need to think of the nitrogen and phosphorous cycles as a crisis.”

Dann Sklarew, George Mason University

Farmers often rely on nitrogen and phosphorous fertilisers that enhance soil nutrients, but can damage other environments. For example, fertiliser being washed off fields has caused ‘dead zones’ in the Gulf of Mexico, where algal growth has reduced the amount of dissolved oxygen so much that fish cannot survive.

The environmental cycles of phosphorus and nitrogen are slow, meaning their artificial addition leads to long-term disruption of natural processes.

SDG 2 and other related goals fail to consider how to avoid overstepping the earth’s ‘fertiliser boundaries’, said Sklarew. Failure to safeguard natural nitrogen and phosphorous resources will also hinder progress towards several other proposed goals, including protecting freshwater supplies (SDG 6) and the health of aquatic ecosystems (SDG 14), and making cities sustainable (SDG 11), he added.

But the goals do not ignore the issue completely: SDG 14 includes a target to reduce marine pollution from land-based sources of nutrients.

Nevertheless, this particular goal fails to link this problem to agriculture, said Sklarew. “There is nothing saying that sustainable agriculture means that if you want high productivity, don’t send your nutrients downstream,” he said.

Sklarew said policymakers should alter SDG 2 to include references to conserving and recycling nutrients in human societies.

Manish Bapna, the managing director of US think-tank the World Resources Institute, agreed. “There are no real, firm planetary boundaries embedded in the goals to which development must aspire,” he told the meeting.

He accepted that “dimensions of sustainability” have been embedded within each goal, and that ecological and environmental issues are fairly well covered, particularly in goals 13 to 15 which set out intentions to combat climate change and halt biodiversity loss, he said. But “they don’t go far enough”, he added.

Bapna said he hoped countries will develop while using natural resources “smartly” without legislation, as agreeing legal limits on phosphorus and nitrogen use would be tricky.

> Focusing on soil health to achieve SDGs