In-season effect of flue gas desulfurization gypsum on soil physical properties.

There is renewed interest in the application of gypsum to agricultural lands, particularly of gypsum produced during flue gas desulfurization (FGD) at coal-burning power plants. We studied the effects of land application of FGD gypsum to corn ( L.) in watersheds draining to the Great Lakes. The FGD gypsum was surface applied at 11 sites at rates of 0, 1120, 2240, and 4480 kg ha after planting to 3-m by 7.6-m field plots. Approximately 12 wk after application, penetration resistance and hydraulic conductivity were measured in situ, and samples were collected for determination of bulk density and aggregate stability. No treatment effect was detected for penetration resistance or hydraulic conductivity. A positive treatment effect was seen for bulk density at only 2 of 10 sites tested. Aggregate stability reacted similarly across all sites and was decreased with the highest application of FGD gypsum, whereas the lower rates were not different from the control. Overall, there were few beneficial effects of the FGD gypsum to soil physical properties in the year of application.