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Earth Today | Soils aren't dirt - Local scientist urges priority for healthly land use

Published:Thursday | October 19, 2017 | 12:00 AMPetre Williams-Raynor
Dr Adrian Spence
The cultivation practices of farmers affect not only the quality of their crops, but also holds implications for Jamaica's efforts to combat climate change.
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WITH SOILS the second largest carbon store after oceans, one local scientist is insisting they must be given their due as Jamaica boosts efforts to minimise the threats of a changing climate.

"I think that any discussion surrounding climate change mitigation and adaptation should involve soils, at least to some extent," said Dr Adrian Spence, research fellow at the International Centre for the Environment and Nuclear Sciences at the University of the West Indies, Mona.

The emission of carbon dioxide and other greenhouse gases are fuel for a changing climate that manifests in not only warmer global temperatures, but also increased sea surface temperatures, sea level rise and extreme weather events, the likes of which were recently felt with the passage of hurricanes Harvey, Irma, Maria, and Jose.

"Soils contain huge amounts of carbon and this can either be a source or a sink. We have almost 30 per cent of the CO2 in the atmosphere coming from the soil. Because of this huge amount of carbon, even small changes, perturbations of that could significantly increase CO2 concentration in the atmosphere," added the biogeochemist.

 

LAND USE CHALLENGE

 

Among the things that can bring that about, Spence explained, are changes in land use and certain other agricultural practices.

"Land use and land use changes is the second leading cause of anthropogenic CO2 emissions, second to CO2 from fossil combustion (electricity, motor vehicle emissions, etc)," he noted.

The caution to value soils is also reflected in information out of the Food and Agriculture Organisation (FAO) of the United Nations (UN), in a 2015 article titled 'Soils help to combat and adapt to climate change'.

"When managed sustainably, soils can play an important role in climate change mitigation by storing carbon (carbon sequestration) and decreasing greenhouse gas emissions in the atmosphere," reads the article published in the year that was designated 'International Year of Soils' by the UN.

"Conversely, if soils are managed poorly or cultivated through unsustainable agricultural practices, soil carbon can be released into the atmosphere in the form of CO2 which can contribute to climate change," it added.

"The steady conversion of grassland and forestland to cropland and grazing lands over the past several centuries has resulted in historic losses of soil carbon worldwide. However, by restoring degraded soils and adopting soil conservation practices, there is major potential to decrease the emission of greenhouse gases from agriculture, enhance carbon sequestration and build resilience to climate change," the FAO article said further.

Spence said it is essential that Jamaicans understand this and work to restore and preserve soil health.

A starting point, he said, is public education.

"The Ministry of Agriculture (for example), through their outreach services, have to basically educate farmers more about these issues; the role that soils play not only in agriculture productivity but also in the climate change context. And certain things should become mandatory," Spence told The Gleaner.

 

PUBLIC EDUCATION KEY

 

He suggests a look at slash and burn, which he describes as "dangerous on many fronts".

"It destroys soil structure, soil fauna. Soils become prone to erosion and all these things as well as you sort of help to break up organic structures leaving them more susceptible to decomposition," explained Spence, who was recently nominated to serve on the prestigious Intergovernmental Panel on Climate Change.

He is to be a lead author for a special report on climate change and land.

It is essential, too, Spence noted, to get a handle on deforestation of pasture lands.

"Grasses store up to 80 per cent of the carbon that they fix in their roots. That is why, for example, grassland contains huge amounts of carbon. Relative to other agriculture land, grasslands contain huge amounts of carbon because they fix carbon in their roots," he said.

"With the deforestation of pasture lands, what you do is remove that fixation process and so that natural process to remove CO2 from the atmospheric pool and store in the soil pool is now taken out of the equation," he added.

"Once you take that out of the equation, what you are left with is respiratory process, that is, microbes will break down organic material in soils, and once this is done, then this produces carbon dioxide which gets emitted in the atmosphere. By removing trees, you remove that balance and you have a bigger flux going from the soils to the atmosphere," the scientist said further.

He urges Government and other stakeholders to support the effort to conserve soils.

"A big push right now, like by the FAO, is to basically unlock the potential of soil for climate mitigation and adaptation. And we should get behind this," he said.

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