ACIDIFICATION OF LIME-STABILIZED BIOSOLIDS IN FORMULATION OF SYNTHETIC TOPSOIL

Uses of lime-stabilized biosolids in container media or topsoil formul ations may be limited by alkalinity imparted by lime added for reducti ons in vector attraction and pathogens and for suppression of odors. T his experiment was conducted to assess the suitability of quicklime-st abilized biosolids mixed with calcareous or noncalcareous sand and wit h sulfur or aluminum sulfate as acidifying agents for development of s ynthetic topsoil for turfgrass (Lolium perenne L.) production. Grass e mergence and growth were inhibited in media that were not amended with an acidifying agent. Additions of aluminum sulfate were more effectiv e in acidification than sulfur, causing an immediate drop in pH, where as additions of sulfur required about 2 months for a depression in med ia pH. With time, electrical conductivities were higher in media with additions of sulfur than in media with additions of aluminum sulfate. Calcareous sand mixed with biosolids (2 sand:1 biosolid, v:v) gave a b etter medium for growth of turfgrass than noncalcareous sand mixed wit h biosolids. Calcareous sand flocculated biosolids, whereas noncalcare ous sand dispersed them. Results suggest that calcareous sand and alum inum sulfate are effective agents for diluting and acidifying biosolid s for development of a suitable topsoil medium for turfgrass productio n.