Environmental and agronomic aspects of municipal solid waste heavy fraction used for turfgrass production

Disposal of municipal solid waste has become a tremendous problem in the United States. To reduce the volume of garbage that requires deposition in landfills, innovative methods of recycling need to be investigated. Several experiments were conducted in Blacksburg, Virginia, to evaluate the use of heavy fraction, a by-product of a solid waste separation process, as a soil amendment for production of turfgrass sod.

In a field plot experiment using Kentucky bluegrass (Poa pratensis L.), measurements of sod strength taken 8.5 and 9.5 months after seeding were greater for sod grown in topsoil amended with heavy fraction than for turf grown in topsoil only. These results imply that the use of this by-product for turfgrass production may reduce the time required to produce a harvestable sod.

In a container study, physical properties of a loam topsoil were altered 16 months after addition of heavy fraction. Bulk density and particle density were reduced and organic matter content increased by soil incorporation of this by-product. Total porosity and air porosity (macropore space) of the topsoil increased whereas water porosity (micropore space) decreased with increasing amount of applied heavy fraction.

Soil fertility was enhanced and soil pH raised by addition of heavy fraction. Concentrations of extractable NH₄ -N, P, K, Ca, Mg, Mn, and Zn in soil were increased by the application of heavy fraction, as were concentrations of K, Ca, S, Mg, and Mn in leachate collected in lysimeter studies. Improved fertility resulted in greater aesthetic quality, clipping yields, and tissue N content for tall fescue (Festuca arundinacea Schreb.).

Lysimeter studies indicated that the greatest environmental concern associated with the use of heavy fraction for turfgrass production appears to be the potential for leaching of N0₃-N during turf establishment. With loading rates of 414,747 kg ha⁻¹ or lower, however, the amount of N0₃-N leached from heavy fraction-amended topsoil was no greater than that leached from topsoil containing no heavy fraction. Concentrations of N0₃-N in leachate for all loading rates of heavy fraction decreased to levels well below 10.0 mg L ⁻¹ approximately two months after sodding the lysimeters with tall fescue. Leachate analyses indicated minimum potential for P or heavy metal contamination of groundwater from heavy fraction.