Effects of Emissions from a Coal‐fired Power Plant on Soybean Production

Abstract

AbstractAn air pollution exclusion system was designed, tested, and operated at four field sites during four growing seasons near the Tennessee Valley Authority Widows Creek Steam Plant to measure the effect of emissions from the coal‐fired power plant on soybean [Glycine max (L.) Merr., cv. Essex] production. Soybean plants were exposed to background levels of ambient air pollutants. When the plume from the power plant was at ground level the air pollution exclusion system was activated and passed charcoal‐filtered air through the plant canopy of the control plots, thereby reducing SO2 concentration to 10 to 20% of ambient level. The maximum 3‐h average SO2 concentration ranged from 1935 to 9944 µg/m3 (from 1972–1975) and from 502 to 1478 µg/m3 (from 1977–1979). Soybean plants were also grown in charcoal‐filtered and unfiltered air in greenhouse chambers for 4 yr (1972–1975) near the Widows Creek Steam Plant and for 3 yr (1977–1979) at a remote site 70 km from the power plant. Soybean yield was significantly reduced by 27% in greenhouse chambers with unfiltered air compared with chambers with charcoal‐filtered air near the power plant. Emissions from the power plant significantly reduced soybean yield by 12% for only 1 out of 4 yr in the field tests. An estimated 6.4% of the total leaf area in the ambient air + SO2 plots showed chlorosis after an exposure to a maximum 1‐h average SO2 concentration of 1663 µg/m3. At the remote location, soybean yield averaged 25% less in unfiltered air than in filtered air, indicating that air pollutants other than power plant emissions were affecting soybean yield at both sites.