Sumedha B S, Bangalore University
Increasing the number of crops isn’t the only way to feed a growing population. This research points out that controlling air pollution is vital to increasing crop production. This method saves land and money.
Improvements in agricultural productivity are a necessity for the coming decades to achieve sustainable development goals. The improvements include reducing hunger, malnutrition, and conservation of biodiversity. One of the many strategies to achieve these goals is to improve air quality.
The levels of pollutants such as ozone have been found to suppress crop yield by 30 to 40%. Better insights into the effects of air pollution are necessary. Older studies of air quality and crop productivity were limited to small-scale experimental manipulations or observational analyses. However, these studies are often associated with uncertainties. These uncertainties arise because of the challenge of extrapolating experimental conditions. The main focus has been on the secondary pollutants (ozone and particulate matter) because of human health concerns. These have been limited to regions where the ground measures are available.
Nitrogen Dioxide: Key Focus of The Study:
Nitrogen oxides (NOx) are the most common pollutants emitted worldwide. Its impact on agriculture is not well known. NOx can damage crop cells and affect growth by promoting ozone (O3) and aerosol formation.
Focusing on NO2 is beneficial as it can be measured with higher precision than most pollutants. Another major benefit is that NO2 is a primary pollutant that is directly emitted from pollution sources. This makes it more straightforward to translate estimated impacts occurring through multiple pathways, to the underlying emissions.
Satellites were used to map nitrogen dioxides with incredibly high precision. This opened up the chance to rapidly improve knowledge of how nitrogen oxides affect agriculture in different regions.
The researchers compared nitrogen dioxide emissions in various regions of the world with the greenness of the cropland.
How do nitrogen oxides affect crops?
In the current study, the scientists combined the TROPOMI measures of NO2 for 2018–2020 with satellite measures of crop greenness to study the role of NO2 in crop productivity. The TROPOMI (TROPOspheric Monitoring Instrument) is novel in its ability to monitor tropospheric nitrogen dioxide (NO2) levels.
The study addressed NOx impacts for five major regions around the world. The fundamental questions addressed in the study- Is there a clear negative association between NO2 and crop productivity throughout different regions, consistent with the idea that NOx is an important factor in crop growth? How much does the effect of NO2 differ by season and region? What do these differences indicate about the effects of NOx? What is the potential gain in crop productivity that could reasonably be expected if NOx levels were reduced in each region?
Results of the study:
Researchers found consistent negative associations between NO2 and greenness throughout regions and seasons. These effects were found to be strongest in conditions where O3 formation is NOx limited. This remained significant even in locations where this pathway is altered
A wide range of crops exposed to NO2 across major growing regions and seasons were observed. NO2 levels were highest in the winter season. This meant the exposure of winter crops including wheat is higher than summer crops. Exposure was highest for crop locations in China, but not all areas of China. The next highest exposure was in India and Western Europe. North and South America had the lowest exposures. All the regions exhibited a considerable range of exposures.
To further distinguish between possible pathways of impact, the scientists partitioned each region into subsets. In the first subset, they identified points having a ratio of HCHO: NO2 > 2. Here, it would be expected that an increase in NOx would lead to an increase in O3. The second subset included all points with a ratio below 2.
Researchers found that NO2 sensitivity was considerably higher for locations where O3 formation was likely to be NOx limited. NO2 sensitivity was still negative in regimes where O3 formation was not NOx limited.
Significance of the study:
The results suggest that O3 is an important pathway for the impact of NO2 but those other mechanisms including direct damage from NO2 likely play an important role in suppressing crop growth. This contributes to as much as half of the total damage in some regions.
Researchers estimate that cutting nitrogen dioxide emissions by 50 percent would improve winter crop yields in China by around 28 percent. Yields could improve by 16 percent in the summer.
In India, researchers predict that the reductions in nitrogen dioxide could increase crop yields by up to 8 percent for winter, and 6 percent for summer. The yields for summer and winter crops in western Europe could increase by 10 percent.
The main take-home message from this study is that the agricultural benefits of these actions could be really substantial. It could be enough to help solve the problem of feeding the growing population. The exact mechanisms and impact of nitrogen oxides on impact plant growth might not be known yet. However, the strong relationship determined in this study suggests air pollution contributes to crop losses all around the world.
Reference:
- Lobell, David B., Stefania Di Tommaso, and Jennifer A. Burney. “Globally ubiquitous negative effects of nitrogen dioxide on crop growth.” Science Advances 8,No.22(2022):eabm9909.https://www.science.org/doi/10.1126/sciadv.abm9909
Also read: Unraveling The Mystery Of Why Touch Stresses Plants Out
Author Info:
Sumedha B S is pursuing MSc in Biotechnology. She is a proactive person with a positive attitude. She is skilled in laboratory techniques of Biotechnology and Microbiology. Her interests include Science communication, Bioinformatics, and Biopharma. She is looking for learning opportunities to build a career in the Biotechnology field. LinkedIn profile: https://www.linkedin.com/in/sumedhaprofile/
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