Effects of soil acidity and cropping on solubility of by-product-immobilized phosphorus and extractable aluminum, calcium, and iron from two high-phosphorus soils

摘要

Large quantities of by-products and increased costs for landfill have heightened interest in using by-products as soil amendments on agricultural lands. There are concerns of potential negative environmental impacts of by-product-amended soils when fields are taken out of agricultural production or polluted area. The objective of this study was to determine the effects of lowering soil pH and cropping on the solubility of phosphorus (P) immobilized by drinking water treatment residue (WTR) and coal combustion bed ash (BA). Two high-P soils (Evesboro sand and Matapeake silt loam) were mixed with two WTR and a BA and incubated for 15 weeks using several wetting and drying cycles. From 15 to 33 weeks, elemental sulfur and 1N H2SO4 were used to adjust soil pH to levels found in the wooded areas adjacent to agricultural fields. Acidified soils were planted with Bermudagrass. By-products reduced extractable P in both soils. Mehlich-3-extractable P that was immobilized in the by-product-amended Matapeake soil did not become soluble after acidification and cropping. Water-extractable P was significantly higher for the control and BA treatments after acidification and cropping. The water-extractable P that was immobilized by WTR before acidification did not become soluble under acidic and cropping conditions in either soil. Although soil aluminum and iron concentrations were higher under acidification and cropping, it was concluded that they were not at levels that would negatively impact the environment.