A simple new device that costs less than US$1 to make could help global efforts to reduce harmful air pollution caused by ammonia emissions, while improving access to food. The small plastic tool was designed by Brazilian scientists in collaboration with the IAEA and the Food and Agricultural Organization of the United Nations (FAO). After isotopic techniques were used to test and confirm the tool’s accuracy, it is now being rolled out to help countries monitor and better manage ammonia emissions from agriculture, including the livestock industry.
Ammonia — which is a compound of nitrogen and hydrogen — is one of the major byproducts of agriculture. It is a gas released as a result of the breakdown of fertilizers and animal manure, among others. This gas (NH3) in the atmosphere can act as a secondary source of nitrous oxide (N20) — a powerful greenhouse gas — and can damage ecosystems by exacerbating water pollution, as well as cause health problems in people.
When fertilizer is not applied correctly, up to half of the nitrogen in fertilizer could be lost to the atmosphere, which also has major financial consequences. Understanding this loss is essential for issuing recommendations to farmers on how best to manage their fertilizer use, which can help maximize productivity and benefits.
“On average, 35% of the nitrogen fertilizers used in Brazil are lost to the atmosphere as ammonia, which has a big impact on the environment and the economy,” said Segundo Urquiaga, a soil scientist at the Agrobiology Research Centre of the Brazilian Corporation for Agricultural Research (EMBRAPA).
As the world population continues to increase, the demand for food grows with it. This, in turn, means expanding livestock industries and an increasing dependence on synthetic and organic nitrogenous fertilizers for food production. It also means more ammonia emissions. This trend is expected to continue over the next decade, which poses a threat to people’s health and the environment.
Experts in countries such as Brazil are looking for ways to measure and mitigate ammonia losses to the atmosphere. Many sophisticated methods, such as wind tunnels, cavity ring down spectroscopy and micrometeorological techniques, are already available, but these are expensive and require highly-skilled field technicians to operate.
“Measuring and mitigating this process has been laborious, time consuming and relatively expensive in the past,” said Urquiaga. “This new technique is cost-effective, fast and can be adopted anywhere. Using it will have a direct impact on farmers who will not only be saving resources but also reducing air pollution.”
A new, unique tool
The new tool is so simple that it could easily be mistaken for a grade-school science project. The chamber is made by removing the bottom of a large soda bottle and attaching it to the open bottle top. This shields a thin strip of foam that runs along the inside of the bottle from the mouth down to a small plastic cup anchored to the soil with three metal prongs. This foam is presoaked in an acid solution that traps ammonia. The chamber is placed alongside the plants or livestock area to be monitored, and the foam is removed every 24 hours and taken to the laboratory for analysis.
This unique and simple device and instructions on how to use it were created by scientists from the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, EMBRAPA and Brazil’s Agronomic Institute of Parana (IAPAR).
“This device could help us understand ammonia losses and move toward climate-smart solutions that leave enough nitrogen to boost plant productivity, especially in less fertile and nitrogen-deficient soil, which can have a major impact on food production,” said Mohammad Zaman, a soil scientist and plant nutritionist at the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture.
The device can be used on its own to precisely measure ammonia losses, as well as in combination with agricultural practices designed to reduce greenhouse gas emissions and their impact on the environment. These practices include drip irrigation systems, co-application of fertilizers with nitrogen process inhibitors and crop rotation involving nitrogen-fixing legumes.
Simple, yet reliable
A major concern with such a simple setup was the reliability of its results. To test this, the scientists used an isotopic technique that involves adding nitrogen-15 to fertilizer (see The Science box) as a way to track, measure and compare the amounts of ammonia captured by the plastic chamber versus how much ammonia was released, which was determined by using the nitrogen mass balance method to check the amount of nitrogen in the soil over time. As ammonia is a compound containing nitrogen, the nitrogen-15 method allows scientists to track the ammonia losses.
The results of the tests showed that the chamber was reliable and suitable for tracking ammonia emissions from organic and synthetic fertilizers used for annual and perennial crops, as well as for excreta in livestock systems. “This method is highly efficient and precise in measuring and monitoring ammonia in comparison to the traditional closed chamber method,” Urquiaga said.
Experts in six countries — Brazil, Chile, Costa Rica, Ethiopia, Iran and Pakistan — have already started using the tool. More widespread use of the tool is expected, said Zaman, with the foreseen publication of the project results in a special edition of a peer-reviewed international scientific journal, as well as with a plan to recommend to the Intergovernmental Panel on Climate Change (IPCC) to include the tool as a method for use in agricultural systems worldwide, especially in developing countries.
Nitrogen plays an important role in plant growth and photosynthesis, the process through which plants use sunlight to synthesize nutrients from carbon dioxide and water. Nitrogen is often added to soil in the form of fertilizer. Using fertilizers labelled with nitrogen-15 stable isotopes — atoms with extra neutrons as compared to ‘normal’ nitrogen — scientists can track the pathway and determine how effectively the crops are taking up the fertilizer as well as the different nitrogen losses including ammonia. The technique also helps to determine the optimal amount of fertilizer to use.