Use of flue gas desulfurization gypsum to reduce dissolved phosphorus in runoff and leachate from two agricultural soils

Abstract

Controlling dissolved phosphorus (DP) loss from high P soil to avoid water eutrophication is a worldwide high priority. A greenhouse study was conducted in which flue gas desulfurization gypsum (FGDG) was applied by using different application methods and rates to two agricultural soils. Phosphorus fertilizer was incorporated into the soils at 2.95 g kg−1 to simulate soil with high P levels. The FGDG was then applied at amounts of 0, 1.5, and 15 g kg−1 soil on either the soil surface or mixed throughout the soil samples to simulate no-tillage and tillage, respectively. Ryegrass was planted after treatment application. The study showed that FGDG reduced runoff DP loss by 33% and leachate DP loss 38% in silt loam soil, and runoff DP loss 46% and leachate DP loss 14% in clay loam soil, at the treatment of 15 g kg−1 FGDG. Mixing applied method (tillage) provided strong interaction with higher FGDG. To overall effect, the mixing-applied method performed better in controlling DP loss from silt loam soil, while surface-applied (no tillage) showed its advantage in controlling DP loss from clay loam soil. In practice it is necessary to optimize FGDG concentrations, application methods, and DP sources (runoff or leachate) to get maximized benefits of FGDG application. The FGDG application had no negative effects on the soil and ryegrass.