Alum Effects On Phosphorus Runoff Loss From Turfgrass Amended with Biosolid.

The objective was to evaluate effects of composted biosolids (CB) and Alum on turfgrass coverage and runoff loss of sediment and soluble P during Tifway bermudagrass establishment from sprigs or transplanted sod. Three replications of eight treatments were installed on a Booneville fine sandy loam soil in box lysimeters (45 x 34 x 13 cm) under greenhouse conditions. Four treatments comprised Tifway sprigged in soil with and without CB (25% v/v) and Alum (0.1 kg Alum/kg CB). Remaining treatments were made up of sod transplanted from Tifway grown with and without CB, which were established with and without a surface spray of Alum solution. Soil coverage of Tifway sprigged in soil mixed with inorganic fertilizer or CB, with and without Alum, was comparable to transplanted sod 25 d after planting. In contrast, the Alum treatment acidified soil and slowed Tifway coverage rates after sprigging in soil mixed with inorganic fertilizer. Runoff of simulated rain (10 cm/hr) was collected for three 8-min. intervals 20 and 37 d after Tifway was planted. Transplanted sod and incorporation of CB before sprigging minimized sediment loss compared to soil alone. Incorporation of Alum with CB or inorganic fertilizer in soil sprigged to Tifway reduced runoff loss of both total dissolved P (TDP) and soluble reactive P (SRP). Mass runoff loss of TDP and SRP for sod transplanted from Tifway grown with topdressed CB was greatest, but a surface application of Alum solution after transplanting sod reduced runoff loss to near zero with and without CB. Comparative runoff losses among treatments indicated Alum effects could be attributed primarily to reaction with and reduced runoff of the SRP fraction of TDP. Alum effectively reduced runoff loss of SRP during Tifway establishment from sprigs or sod, but could acidify soil and limit coverage rates after sprigging.