Researchers study how soils are recovering as the air gets cleaner following the 1970 Clean Air Act.
Before the United States 1970 Clean Air Act, rainfall all over the country was acidic. As precipitation would fall from the sky, it would mix with gases from industrial plants, emissions from cars, and especially coal and fossil fuel consumption. That caused the water to become acidic – also called “acid rain.”
Besides the air pollution hurting plants and humans, this acid rain also hurt our soils. Even dry deposits of these acidic emissions could be hurtful to humans, plants, soil and water. Acidic soil can bind nutrients so that plants can’t get them. It can hurt the microbes in soil, as well as plants.
One odd “helpful” thing acid rain did, though, was to provide a few nutrients to the soil. The sulfur in the acid rain – in the form of sulfates – actually provided nutrition to plants. However, the benefit was negligible, and the overall effects of pollution required regulation. Occasionally, cities like Los Angeles will still experience “smog.” The incidents are even more common in China and India, where little regulation is in effect.
Continue reading at American Society of Agronomy
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