Quarry Fines as Mineral-Base Material in Constructing Topsoil for Turfgrass Purposes.

Tightening specifications for the use of aggregates in asphalt and cement mixes result in increase inventory of fines byproduct by the aggregate industry. A study was conducted to characterize quarry fines (<6.35 mm) byproduct of different rock materials (sandstone, limestone, granite, greenstone, and marble) and to evaluate their use in constructed topsoil. Two acidic subsoils (Gilpin B_t, Dekalb B_w) and two processed chicken litter products (composted, and anaerobically digested) were added incrementally in a batch titration setting to lower the medium alkaline pH of the fines. Hydraulic properties of the rock materials, and of selected mixes thereof with subsoil were evaluated. Constructed quarry-subsoil mixes (at 75 to 25% mixing ratio), amended at three levels (0, 8, and 12% by weight) with processed urban, and agricultural organic waste materials (composted chicken litter, anaerobically digested chicken litter, turkey compost, and yard-waste compost) were used in a pot experiment where Falcon III, a turf type tall fescue cultivar (Festuca arundinacea Schreb. cv. ‘Facon III’) was grown for 80 days. Germination, % cover, and clipping mass were recorded during the experiment, and total aboveground biomass, and chemical and physical properties of the topsoil media were determined at the end of the experiment. The pH of quarry-based mixtures averaged 7.6±0.5, with the highest values in the limestone fines mixes (7.9±0.2). The constructed topsoil mixes improved the hydraulic conductivity of the subsoil and the water retention of the quarry fines. Turfgrass growth performances were comparable to that of commercial topsoil replacement mix, used as a reference. Performances were mostly affected by the organic amendment source, with notable poor performances of the yard-waste compost. The results of this study point to the additional value of quarry fines and anaerobically digested chicken litter in constructing topsoil mixes for turfgrass purposes.