Reducing air pollution can improve crop yields by reducing the negative impacts of nitrogen oxides (NOx) on plant growth, scientists say.
“Overall, we find a remarkably consistent negative association between nitrogen dioxide (NO2) and crop growth in major cropping regions,” write the researchers.
“These results indicate that reduction of NOx emissions could have important benefits for crop production, sometimes exceeding 30% of current yields.”
They add that “the magnitude of these effects have the potential both to alter overall yield growth rates (which are typically around 1% per year) and substantially change cost-benefit analysis for pollution mitigation measures.”
Some NOx emissions are phytotoxins—or a source of phytotoxins like ozone—that lower yields by damaging plant growth. They can also lead to the formation of aerosols that reduce the amount of sunlight available for plants to photosynthesize, thereby diminishing productivity. While researchers are aware of these impacts, they have not fully quantified their effect on crop yields, due to limitations of measuring tools and the complexity of interactions between various states of nitrogen oxides and the processes of plant biology.
“By directly relating NO2 to crop productivity, we capture the net effects of many pathways of impact and recovery in actual farmers’ fields, which encompass a diversity of conditions that would be impossible to recreate in controlled experiments,” the authors write.
The study overcomes these limitations by using satellite measurements of NO2pollution and crop greenness in five major food-producing regions of the world. Among the studied regions, crop exposure to NO2 was highest in China, followed by India and Western Europe. North and South America generally had the lowest exposures.
The results show that actions to reduce air pollution levels could counteract the negative impacts and lead to gains in crop production. Reducing NO2 could lead to a 28% yield gain for winter crops in China, 10% for winter and summer crops in Western Europe, and gains of 8% and 6% for summer and winter crops in India.
According to the researchers, such improvements in agricultural productivity are increasingly needed to achieve sustainable development goals like reducing hunger and increasing protections for forests and biodiversity.
“A better understanding of the agricultural impacts of air pollution would help to better assess both the potential benefits of air quality improvements and how prominent a role pollution reduction should have among efforts to raise agricultural productivity,” they say.