Felicity Hayes checks on her vegetables in one of eight tiny domed greenhouses in Wales. The lush spring-planted pigeon pea and papaya will shortly yield fruit.
same plants seem sickly and stunted in a neighbouring greenhouse. Papaya trees are half as tall as the pigeon pea’s yellow, pockmarked leaves.
The only difference is ozone pollution.
Hayes, of the UK Centre for Ecology and Hydrology (UKCEH), pumps ozone gas into African greenhouses. She studies how growing ozone pollution may affect crop production and food security in poor countries.
Ozone is a gas that is made when sunlight, heat, and fossil fuel emissions come together. It may cause farmers to lose a lot of money by causing crops to age before they reach their full yield potential and by stopping photosynthesis.
Ozone weakens plants’ pest defences.
A 2018 study found that ozone pollution cost the world $24.2 billion worth of wheat every year from 2010 to 2012.
In a January article in Nature Food, researchers said that East Asia loses $63 billion worth of wheat, rice, and maize every year.
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As Africa’s population doubles by mid-century, scientists predict increasing vehicle traffic and garbage burning.
This means more ozone pollution, which is a problem for the 60 percent of smallholder farmers in sub-Saharan Africa.
Senior scientist Martin Moyo of the International Crops Research Institute for the Semi-Arid Tropics in Zimbabwe said ozone pollution might damage harvests over time.
He advocated for “immediate” rural ozone investigations across the continent.
CABI scientists installed ozone monitoring equipment in cocoa and maize fields in Ghana, Zambia, and Kenya this year.
UNICEF reports that most African nations lack dependable air pollution sensors. Few monitor ozone.
Ozone rising
Ozone shields Earth from UV rays in the stratosphere. It can injure plants, animals, and humans near the surface.
Air quality rules have helped cut ozone levels in the U.S. and Europe, but the trend will reverse in fast-growing Africa and portions of Asia.
Climate change might help.
A new study shows that in parts of Africa where fossil fuels are burned a lot and forest or grassland fires happen often, hotter temperatures can speed up the chemical processes that make ozone.
Wheat in Europe and Asia is more affected by ozone than wheat in North America. However, less research has been done on African versions of the same crops that have changed over time.
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Farmers from the rural areas send ill crops to a “plant doctor” at a Nairobi market every two weeks.
Lena Durocher-Granger, a CABI entomologist, said ozone symptoms might be mistaken with mites or fungal damage. “Farmers may keep spraying pesticides, believing it’s an illness, but it’s ozone pollution.”
Her group works with UKCEH to identify ozone stress and offer remedies, such as watering less on high ozone days. Watering opens leaf pores, allowing plants to absorb more ozone.
Resilient crops
Hayes exposed crops in one dome to 30 ppb, equivalent to North Wales, in her Welsh greenhouses. In the highest ozone dome, plants received quadruple that amount, simulating North Africa’s pollution.
Certain African staples are more affected than others, according to Hayes.
Within a few months, North African wheat plants turned yellow under an ozone-filled dome.
Hayes: “You get little thin grains with a lot of husk on the exterior and less protein and nutritional value.”
According to studies her team released last year on sub-Saharan plant varieties, ozone pollution might reduce wheat yields by 13%.
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According to the same study, dry beans might suffer output losses of up to 21% in some places.
Katrina stated, “Beans are a good nutrition source for subsistence farmers in Africa.”
UKCEH Data Analyst Sharps
Sub-Saharan millet is ozone-tolerant. In 2020, Africa will grow half as much millet as wheat.
“Subsistence farmers may grow more millet if the land and conditions are right,” Sharps added.
