High rates of surface-applied FGD-gypsum decrease soil P availability under short-term flooding

Method Soil samples (10cm depth) of the Toronto-Millbrook complex soil (Udollic Epiaqualfs) were used in this study. The experiment consisted of the evaluation of 3 different FGD-gypsum treatments (0 (control); 1000 (G); 2000 (GG) kg ha) and was performed in triplicate in an oxygen-free gas biogeochemical reactor where 80 g of sieved soil (2 mm) plus surface applied FGD-gypsum and 120 mL of degassed DI water were incubated in centrifuge bottles for 1,7,14, and 21 days of saturation at 25±0.5°C. Soil solution samples were collected after each incubation period in a glove bag saturated with N2 gas then centrifuged, filtered (0.45 um), and analyzed for Ca, K, Mg, P using an ICP-OES. Eh and pH were measured after 1hour and 21 days of saturation.