Increasing the Sustainability of Sod Production Using Biosolids

Land application of municipal biosolids can improve soil physical properties while providing turfgrass with essential nutrients. Biosolids may also mitigate the loss of soil from sod producing fields during sod harvest operations. The objective of this study is to increase the profitability and sustainability of sod production using biosolids-based systems at sod production farms in Wisconsin and Virginia. These production systems were designed to limit soil removed during harvest, reduce fertilizer and pesticide inputs, and provide an economical approach to biosolids reuse. Three 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 soil and in Remington, Virginia on a Cordorus silt loam soil. The Wisconsin project utilized two materials from the Madison Metropolitan Sewage District (dewatered class B biosolids “cake” and biosolids mixed with sand and sawdust), and applied both 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. The Virginia project utilized two materials from the Alexandria Sanitation Authority (anaerobically-digested class A cake and this material blended with fine wood chips), and applied at three rates based on their estimated supply of plant available nitrogen. Biosolids were incorporated to a depth of 5 cm and plots were seeded to ‘Midnight' Kentucky bluegrass (Poa Pratensis) in Wisconsin, and ‘Rebel IV' tall fescue (Festuca arundinacea) in Virginia. During establishment in 2009, turf quality, stand density, color, and soil volumetric moisture content were measured. Preliminary data from Wisconsin showed that applying biosolids cake at double the annual turf nitrogen demand (500 kg N ha-1) resulted in significantly higher turf density and color compared to applying at the annual nitrogen rate. Furthermore, biosolids cake applied at ≥ 500 kg N ha-1 had quality and color similar to or better than the conventional maintenance control throughout establishment. Preliminary data from Virginia showed that applying biosolids cake at 1.5 times the annual turf nitrogen demand (300 kg N ha-1) resulted in significantly higher turf density and color compared to applying at the annual nitrogen rate. Furthermore, biosolids cake applied at 300 kg N ha-1 had quality and color similar to or better than the conventional maintenance control throughout establishment. These preliminary results suggest biosolids-based sod production can meet agronomic goals. Economic and soil loss data during harvest analysis is ongoing.