According to the research of Californian scientists, air pollution with nitrogen oxides has an adverse effect on crops. If we reduced their levels in the atmosphere globally, we would see significant increases in yields in some regions.
Nitrogen oxides are one of the most widespread air pollutants in the world. Although their harmfulness to plants is well documented scientifically, until now we did not know to what extent they affect agricultural production in the world. It turns out that reducing the level of these chemicals in the atmosphere can bring about a noticeable increase in yields.
Higher yields in summer and winter
A team of scientists from Stanford University and the University of California in San Diego analyzed satellite images of agricultural land in the United States, China, India, Western Europe and North America. Based on the color of the plants, researchers assessed the condition of the crops and compared it with satellite data showing the level of nitrogen dioxide pollution at a given location on Earth. The study was conducted on data from 2018-2020.
The analysis showed that the crops in each of the studied sites were exposed to nitrogen dioxide from urban areas – it had the greatest impact on agricultural areas in China, India and Western Europe.
Scientists calculated that reducing the content of an element in the atmosphere to background level, or 5 percent of its current value, could increase China’s winter crops by 28 percent and spring crops by 16 percent. A noticeable, nearly 10% increase would also occur in Western Europe, regardless of the season. In contrast, India is projected to increase by 6 percent for winter crops and 8 percent for summer crops.
Various effects on plants
Nitrogen oxides appear in the atmosphere as a result of emissions from transport and energy, and to a lesser extent from agriculture. They are phytotoxic – this means that they damage plant tissues. They also act as catalysts for the reactions that produce ozone. Although it plays an important protective role in high layers of the atmosphere, it is a strong oxidant close to the ground, negatively affecting the condition of plants.
The lead author of the study, Dr. David Lobell of Stanford University, noted that the model proposed by the scientists does not take into account some physiological factors, such as the internal mechanisms of plant defense against nitrogen oxides and ozone. He also emphasizes the need for further studies, this time taking into account other phytotoxic pollutants, including sulfur dioxide and ammonia.
Main photo source: Aleksandr Ozerov / Shutterstock