The Effect of Biosolids On Kentucky Bluegrass Sod Establishment.

Land application of municipal biosolids can improve soil physical properties while providing turfgrass with nutrients. Biosolids may also mitigate the loss of soil from fields during sod harvest. The objective of this study is to increase the profitability and sustainability of sod production by developing a biosolids-based sod production system in Wisconsin. Four replications of seven treatments were arranged in a randomized complete block design at a sod production farm in Marshall, WI on a Dodge silt loam (Fine-silty, mixed, superactive, mesic Typic Hapludalfs). Plot size was 25 m by 8 m, and all operations were performed using farm equipment. Two biosolids materials were utilized from the Madison Metropolitan Sewage District (dewatered class B biosolids cake and cake mixed with sand and sawdust), and were applied at three rates based on their estimated supply of plant available nitrogen. The final treatment was a control which mimicked conventional sod maintenance techniques including synthetic nitrogen fertilizer. Biosolids were incorporated to a depth of 5 cm and plots were seeded with Kentucky bluegrass (Poa pratensis). Establishment density, turf quality, turf color, and soil volumetric moisture content were measured weekly. Preliminary data showed that applying biosolids cake at 500 kg ha^-1 of plant available N resulted in significantly similar establishment density, turf quality, and turf color compared to the standard sod production practice, which consisted of inorganic fertilizer applied at 250 kg N ha^-1. Furthermore, biosolids cake applied at 250 kg ha^-1 of plant available N resulted in significantly greater sod tensile strength than the standard practice. These results suggest biosolids-based sod production can meet or exceed current agronomic goals for sod production in Wisconsin.