Nitrogen pollution: the forgotten element of climate change


Ee Ling Ng, University of Melbourne; Deli Chen, University of Melbourne, and Robert Edis

While carbon pollution gets all the headlines for its role in climate change, nitrogen pollution is arguably a more challenging problem. Somehow we need to grow more food to feed an expanding population while minimising the problems associated with nitrogen fertiliser use.

In Europe alone, the environmental and human health costs of nitrogen pollution are estimated to be €70-320 billion per year.

Nitrogen emissions such as ammonia, nitrogen oxide and nitrous oxides contribute to particulate matter and acid rain. These cause respiratory problems and cancers for people and damage to forests and buildings.

Nitrogenous gases also play an important role in global climate change. Nitrous oxide is a particularly potent greenhouse gas as it is over 300 times more effective at trapping heat in the atmosphere than carbon dioxide.

Nitrogen from fertiliser, effluent from livestock and human sewage boost the growth of algae and cause water pollution. The estimated A$8.2 billion damage bill to the Great Barrier Reef is a reminder that our choices on land have big impacts on land, water and the air downstream.

Lost nitrogen harms farmers too, as it represents reduced potential crop growth or wasted fertiliser. This impact is most acute for smallholder farmers in developing countries, for whom nitrogen fertiliser is often the biggest cost of farming. The reduced production from the lost nitrogen can represent as much as 25% of the household income.

The solution to the nitrogen challenge will need to come from a combination of technological innovation, policy and consumer action.

The essential ingredient

Nitrogen is an essential building block for amino acids, proteins and DNA. Plant growth depends on it; animals and people get it from eating plants or other animals.

Nitrogen gas (N₂) makes up 78% of the air, but it cannot be used by plants. Fertilisers are usually made from ammonia, a form of nitrogen that the plants prefer.

A century after the development of the Haber-Bosch process gave us a way to manufacture nitrogen fertiliser, our demand for it has yet to level off.

The use of nitrogen fertiliser has risen from 11 million tonnes in 1961 to 108 million tonnes in 2014. As carbon dioxide levels continue to rise in the atmosphere, some plants such as grains will also likely demand more nitrogen.

Wheat with and without nitrogen fertiliser.
Deli Chen/ The University of Melbourne

In fact, nitrogen from fertiliser now accounts for more than half the protein in the human diet. Yet some 50% of applied nitrogen is lost to the environment in water run-off from fields, animal waste and gas emissions from soil microbe metabolism.

These losses have been increasing over the decades as nitrogen fertiliser use increases. Reactive nitrogen causes wide-ranging damage, and will cause more damage if nitrogen losses are not reined in.

Faced with a growing population and changing climate, we need more than ever to optimise the use of nitrogen and minimise the losses.

From farm to fork

One way to understand our nitrogen use is to look at our nitrogen footprint – the amount of nitrogen pollution released to the environment from food, housing, transportation and goods and services.

Research by University of Melbourne PhD candidate Emma Liang shows Australia has a large nitrogen footprint. At 47kg of nitrogen per person each year, Australia is far ahead of the US, which came in with 28kg of nitrogen per person.

A high-animal-protein diet appears to be driving Australia’s big nitrogen footprint. The consumption of animal products accounts for 82% of the Australian food nitrogen footprint.

Animal products carry high nitrogen costs compared to vegetable products. Both products start with the same cost in nitrogen as a result of growing a crop, but significant further losses occur as the animal consumes food throughout its life cycle.

The N-Footprint project aims to help individuals and institutions calculate their nitrogen footprints. It shows how we can each have an impact on nitrogen pollution through our everyday choices.

We can choose to eat lower nitrogen footprint protein diets, such as vegetables, chicken and seafood instead of beef and lamb. We can choose to reduce food waste by buying smaller quantities (and more frequently if necessary) and composting food waste. The good news is, if we reduce our nitrogen footprint, we also reduce our carbon footprint.

Back to the farm

In the meantime, efforts to use nitrogen more efficiently on farms must continue. We are getting better at understanding nitrogen losses from soil through micrometerological techniques.

From sitting in the sun with plastic bucket chambers, glass vials and syringes, scientists now use tall towers and lasers to detect small changes in gas concentrations over large areas and send the results directly to our computers.

Eddy covariance tower.
Mei Bai/ The University of Melbourne

We now know nitrification (when ammonia is converted to nitrate) is an important contributor to nitrogen losses and therefore climate change and damage to ecosystems. It is a process researchers – and farmers – are targeting to reduce nitrogen losses.

Nitrification inhibitors are now used commercially to keep nitrogen in the ammonium form, which plants prefer, and to prevent the accumulation of nitrate, which is more easily lost to the environment.

As this technology advances, we are starting to answer the question of how these inhibitors affect the microbial communities that maintain the health of our soil and form the foundation of ecosystems.

For example, our research shows that 3,4-dimethylpyrazole phosphate (better known as DMPP) inhibits nitrification without affecting soil microbial community diversity.

There have also been exciting observations that the root systems of some tropical grasses inhibit nitrification. This opens up a management option to slow nitrification rates in the environment using genetic approaches.

Solving the challenge of nitrogen use will require research into more efficient ways for primary producers to use nitrogen, but it will also need government leadership and consumer choices to waste less or eat more plant protein. These tools will make the case for change clearer, and the task of feeding the world greener.


On December 4-8, leading international researchers are meeting in Melbourne for the 7th International Nitrogen Initiative Conference to discuss the best new solutions to problems in nitrogen use. For a more in-depth look at these issues, visit the INI2016 website or join a range of food and production experts at the Good Food for 9 Billion: Community Forum.

The Conversation

Ee Ling Ng, Research fellow, University of Melbourne; Deli Chen, Professor, University of Melbourne, and Robert Edis, Soil Scientist

This article was originally published on The Conversation. Read the original article.

Great Barrier Reef report to UN shows the poor progress on water quality


Jon Brodie, James Cook University

The Australian and Queensland governments have delivered their progress report to the UN on the Reef 2050 Plan to ensure the long-term survival of the Great Barrier Reef.

The report focuses on water quality, and managing pollution runoff, but only deals in a superficial way with the other preeminent issue for the reef – climate change.

It shows recent progress on water quality has been slow, and ultimately we will not meet water quality targets without major further investments.

Progress?

The progress report claims some success in managing water quality through improved practices in sugarcane cultivation under the SmartCane program, and in rangeland grazing.

But actual reductions in sediment and nutrients loads to the reef over the last two years have been very small, as shown in the Reef Report Card 2015. This contrasts with the first five years of Reef Plan (2008-2013) where there was modest progress, as you can see below.


Great Barrier Reef Report Card 2015

The positive news out of the Report Card was that grain cropping and non-banana horticulture were doing well, but these are the industries we have little robust data on.

And there’s been little progress towards adequate management practices in sugarcane and rangeland grazing as well as gully remediation in the large dry tropics catchments of the Burdekin, Fitzroy and Normanby.

The specific actions and funding promised in this area over the next five years mentioned in the progress report which have some real substance are:

  1. Direct a further A$110 million of Reef Trust funding towards projects to improve water

  2. Bring forward the review of the Reef Water Quality Protection Plan and set new scientifically based pollutant load targets

  3. Invest A$33 million of Queensland government funding into two major integrated projects

  4. Better prioritise of water quality as a major theme in Reef 2050 Plan.

What we need to do

However these fall far short of the real requirements to meet water quality targets on the reef, set out in the Reef 2050 Plan and the Reef Water Quality Protection Plan.

The best estimate is that meeting water quality targets by 2025 will cost A$8.2 billion. Other estimates suggest we’ll need at least A$5-10 billion over the next ten years.

If we assume that about A$4 billion is needed over the next five years, the amounts mentioned in the progress report (perhaps A$500-600 million at most) are obviously totally inadequate.

There is thus almost no chance the targets will be reached at the nominated time.

This reality has been clearly acknowledged by Dr David Wachenfeld, the Director of Reef Recovery at the Great Barrier Reef Marine Park Authority. In fact the current progress towards the targets is so poor that we will not even get close.

The actions actually needed to manage water quality for the Great Barrier Reef are well known and have been published in the Queensland Science Taskforce Report
and scientific papers.

The most important of these are:

  1. Allocate sufficient funding (A$4 billion over the next five years)

  2. Use the legislative powers already available to the Australian government under the Great Barrier Reef Marine Park Act (1975) and the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act) to regulate agriculture and other activities in the reef’s water catchment

  3. Examine seriously the need for land use change in the reef catchment. For example, we may need to look at shifting away from more intensive forms of land use such as cropping, which produce more pollutants per hectare, to less intensive activities such as beef grazing, forestry or conservation uses

  4. Continue to improve land management in sugarcane, beef grazing and horticulture but acknowledge the need to extend these programs. We also need better practices in urban and coastal development

  5. Critically examine the economics and environmental consequences of the further expansion of intensive agriculture in the reef’s catchment as promoted under the Australian government’s Northern Australian Development Plan

Progress on water quality management for the Great Barrier Reef, as clearly reported in the 2015 Report Card is poor. There is little chance we will reach the water quality targets in the next ten years, without upping our game.

The Conversation

Jon Brodie, Professorial Fellow, ARC Centre of Excellence for Coral Reef Studies, James Cook University

This article was originally published on The Conversation. Read the original article.