| Long term application of manure fertilizer has resulted in elevated phosphorus (P) concentrations in soils on Maryland's Eastern Shore. Using amendments that convert soluble P to insoluble forms may reduce P export from soils to runoff. This three year study examined the effect of coal combustion byproducts (CCPs) on soil, plant and runoff properties from P-enriched soils. Four rates (0, 10, 20 and 40 g kg-1 soil) of different CCPs (fluidized bed combustion ash, flue gas desulfurization gypsum, and anthracite refuse ash) were incorporated into the top 5 cm soil of 48 field plots under corn (Zea mays L.) production. In the first year only, all CCPs reduced dissolved P (DP) in runoff by 20% to 47% relative to the control. Total P (TP) concentrations, however, were not significantly affected by CCP additions due to high rates of erosion (dissolved P accounted for only 29% of TP in runoff). In soil samples collected from 0--15 cm, two of the CCPs continued to reduce water extractable P (WEP), an indicator of P release to runoff, throughout the study by up to 40%. Phosphorus uptake and corn yield were not affected by CCP treatments; however, significant increases in boron, lead, and zinc were observed in plant tissue. Results indicate that CCPs reduced WEP which in turn reduced DP in runoff. More research is needed to further evaluate long-term effects of P reduction and potential metal accumulation in soils amended with CCPs. |
