Ozone pollution: an underappreciated issue in agriculture

Much of the attention surrounding air pollution in developing countries tends to focus on its impact on human health in large cities or damage to important historic buildings. However, its impact on agricultural production is yet to get the attention it deserves.

Research on the impact of air pollution on food is relatively recent, yet all indications suggest that reducing air pollution benefits food production and thereby, global food security. 

In a world faced with much unrest and uncertainty, global food insecurity is an additional driver of turmoil. The importance of this issue, and its implications for both pollution control and agricultural policy, has not been recognized by many national and international agencies.

While ozone has been shown to be the most important air pollutant affecting national crop production in North America and western Europe, mainly because it is found at phytotoxic concentrations over large areas, its impact in the developing countries of Asia, Africa and Latin America, where the economic and social consequences of loss of production may be much greater, is uncertain.

Although the information available on rural ozone concentrations is very limited, it does show that these concentrations can be high enough to have adverse effects on sensitive species, while a limited number of experimental studies (mainly in India) have shown decreases in yield of staple crops due to ambient ozone.

Current projections of rising emissions of ozone precursors suggest that the impacts on agriculture may increase very rapidly over the next two decades.

There is an urgent need for more rural studies to determine ozone concentrations and their impact on major crop species in order to assess the current scale of the problem and to develop models to estimate the future impacts of increased emissions.

ICRISAT's response

ICRISAT researchers in Africa and South Asia are working on adapted cropping system management practices and breeding new varieties of crops that are more resilient to ozone pollution.

To feed the rapidly growing global population, especially in the drylands, ICRISAT works on what we call future grains or Smart Food crops, developing a new generation of crop cultivars or varieties that are both highly productive in future climates and highly tolerant to biotic and abiotic stresses that are likely to become more prevalent in the future. Over 30 improved varieties of sorghum and millets have been developed by ICRISAT and its partners as of 2021.

Research shows that some crops are more sensitive than others to ozone exposure. Dicot species (soybean, cotton and groundnut) are more sensitive to yield loss caused by ozone than monocot species (sorghum, field corn and winter wheat). Potato, rice and maize are moderately sensitive.

ICRISAT crop breeding programs target the increasing or maintaining the yield as well as increasing the stability of yield under stress.

The Programs also works on crop models that help in determining how different scenarios such as air pollution, increased temperature, reduced rainfall will affect crop yields. This helps in informing management decisions.

ICRISAT, together with the Australian National University and the University of South Australia, are also working on a project that has introduced soil moisture and nutrient monitoring tools, the chameleon and wetting front detector, which help in irrigation scheduling and subsequent ozone uptake.

Although not easy, there still needs to be more field research to help quantify the impacts of air pollution on crop yield and quality. 

What researchers and policymakers can do…

Crop breeding programs should include a test for ozone sensitivity to develop more resistant varieties. Future crop management strategies should consider ways of reducing ozone uptake into crops, for example by withholding irrigation during ozone episodes.

Efforts should be made towards incentivizing smallholder farmers for carbon credits for their contributions towards carbon neutrality. Through payments for carbon credits to farmers, agriculture serves as part of the solution to climate change

Further research is needed to improve our ability to quantify and forecast the effects of ozone on crop yield and quality.

Field-based experiments are required, especially to enhance knowledge on the impacts of ozone on crop quality, such as protein yield, sugar and mineral content to assess the impacts of ozone on nutritive value.

Ozone pollution is a global problem requiring investments from industry and governments from around the world. Improved quantification of impacts of ozone within the context of climate change is urgently required to facilitate improved future planning of the availability of food at a range of scales - national, regional and global.

Banner image: The chameleon and wetting front detector, which help in irrigation scheduling and subsequent ozone uptake.

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