Method that cuts sugarcane emissions gets global prize

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A Brazilian scientist who developed a method that reduces greenhouse gas emissions from sugarcane cultivation has been awarded a prize that each year recognises a researcher whose work has excelled in the area of fertiliser use.

Heitor Cantarella received the International Fertilizer Association’s (IFA) Norman Borlaug Award on Global Fertilizer Day, on 13 October — the date German chemist Fritz Haber discovered the synthesis of ammonia in 1908.

Cantarella’s work enables a 95 percent reduction in emissions of nitrous oxide associated with cane cultivation.

Sugarcane is used to produce bioethanol and therefore already contributes to a reduction in carbon dioxide emissions from the burning of fossil fuels. But it releases nitrous oxide which, pound for pound, causes a greenhouse effect approximately 300 times greater than carbon dioxide.

The fertilisers used in agriculture play a significant role in reducing the release of nitrous oxide. Cantarella created a method where urease inhibitors are used during the cultivation of cane to prevent the transformation of urea — the most used fertiliser in Brazilian agriculture — into carbon dioxide. Nitrification inhibitors are also used to block the transformation of ammonia into nitrate.

This is an important step in reducing nitrous oxide emissions, because bacteria in the soil convert nitrate to nitrous oxide and other gases. The researchers calculated a reduction rate of 85-95 percent for soils with urea and inhibitors, compared with soil with urea or soil without fertilisers.

Sugarcane harvest, Brazil: sugarcane cultivation typically produces high levels of environmentally harmful nitrogen emissions, due in large part to the application of urea fertiliser, such as is usual in Brazil.
Sugarcane harvest, Brazil: sugarcane cultivation typically produces high levels of environmentally harmful nitrogen emissions, due in large part to the application of urea fertiliser, such as is usual in Brazil.
Sweeter Alternative, Flickr CC

Brazil is the greatest sugarcane producer in the world and the main exporter of ethanol, which also powers 40 percent of vehicles in the country.

But “if we do not control the emissions associated with the production of ethanol, we can lose the benefits of replacing fossil fuels,” said Cantarella, director of the Center for Research and Development of Soils and Environmental Resources at the Agronomic Institute of Campinas, in an interview with SciDev.Net. “The role of the use of fertilisers is important to adopt mitigating practices.”

As a signatory to the Paris Agreement on climate change, Brazil must reduce emissions by 43 percent by 2030. Making sugarcane cultivation sustainable can contribute to this.

In order to fulfill these international commitments, the Brazilian government is currently discussing the Renovabio, a biofuels regulation policy that sets emissions reduction targets.

“The rationalisation of the use of fertilisers puts the production of cane and consequently, ethanol, on a path towards becoming a more sustainable commodity, increasing its value as a replacement for fossil fuels,” says physicist Newton La Scala Junior, from Paulista State University in Sao Paulo.

Burning sugarcane field near Bundaberg, Queensland; typically, sugarcane cultivation produces high levels of environmentally harmful nitrogen emissions.
Burning sugarcane field near Bundaberg, Queensland; burning of straw residues during harvest is responsible for carbon dioxide emissions and respiratory problems.
srv007, Flickr CC

However, cane cultivation faces challenges in addition to the need for judicious use of fertilisers. One example is the burning of straw residues during harvest, which is responsible for carbon dioxide emissions and respiratory problems due to inhalation of smoke and soot.

Alternatives to the burning of these residues are being studied. La Scala and other researchers are also investigating the benefits of leaving straw lying above ground, to help decrease erosion and provide soil nutrients.

Further reading

This piece was originally published by SciDev.Net’s Latin America and Caribbean desk. It has been republished here courtesy of SciDev.Net's Creative Commons licence.

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