Air Quality Improvements Lead to More Sulfur Fertilizer Use

Sulfur, an essential nutrient for plants, was as free as air back in the 1980s, drifting down onto farmer’s fields from the polluted sky. The nutrient also caused acid rain, however, and it triggered chemistry that meant more mercury in fish. Regulations led to less sulfur in the air, but in the Midwest, where sulfur-hungry corn and soybean fields were proliferating, crops still needed the nutrient. “We find a clear increase in sulfur fertilizer use commensurate with a decline in atmospheric deposition,” said Eve-Lyn Hinckley, a CIRES Fellow, CU Boulder ecologist, and lead author of a new assessment of sulfur fertilizer use.