Spills of petroleum-based products on turfgrass happen primarily because of equipment failure or improper refueling. Hydrocarbons are a major component of fuels and hydraulic fluids, and are hazardous to the environment (Aislabie et al., 2006). Soils contaminated by hydrocarbons become hydrophobic, which reduces the availability of the water-soluble nutrients (Everett, 1978). Also, the elevated carbon content in hydrocarbon-contaminated soil causes an increased carbon (C) to nitrogen (N) ratio resulting in decreased bioavailability of nitrogen and phosphorus (Aislabie et al., 2006). Damage caused by hydrocarbons to turfgrass can be long lasting and difficult to correct due to slow degradation of most hydrocarbons by microbes in soils (Aislabie et al., 2006; Elliott and Prevatte, 1995).
Johns and Beard (1979) compared activated charcoal and a detergent on the remediation of gasoline, motor oil, grease, and hydraulic fluid spills on ‘Tifgreen’ bermudagrass (Cynodon dactylon). Their results showed that a combination of charcoal and detergent can remediate motor oil damage in 3–4 weeks but not for gasoline. However, the results found by Powell (1981) on a motor oil spill on a ‘Penncross’ creeping bentgrass (Agrostis stolonifera) putting green indicated that flushing with dishwashing detergent was more effective than remediation with charcoal or calcined clay. Greenwalt (2003) recommended flushing and scalping before reseeding to reestablish turfgrass on soils contaminated with hydraulic fluid because many commercial products do not provide satisfactory remediation. The work by Bai and Li (2013) showed that using a liquid humic amendment to remediate soil and reseed perennial ryegrass immediately after a gasoline spill was able to reestablish acceptable turf quality in 5 weeks. However, diesel and hydraulic spills showed residue effect up to 2 months and reestablishment of turfgrass was not successful until 4 months after the spill (Bai and Li, 2013). An effective reestablishing method is yet to be identified for damages in cool-season lawns caused by diesel or hydraulic fluid spills.
Bioremediation is a process of using microbes to degrade hydrocarbons (Aislabie et al., 2006). Nitrate nitrogen added to soils contaminated by hydrocarbons was reported to benefit the bioremediation (Bai and Li, 2013; Norris and Dowd, 1993). In general, results from previous research indicate that leaching contaminants with detergent water and applying absorbents such as a humic substance and activated charcoal are the most effective methods for reclaiming soils subjected to petroleum-based spills. Previous works focused on cleaning up the spills and recovery of damaged turf. There has been no information about the effects of mulching on the remediation and reestablishment of turfgrass from reseeding after petroleum-based spills. When recovery of fuel-damaged turfgrass takes too long, it is unpractical to rely on recuperation of the grass but reseed (Bai and Li, 2013). The objective of this study was to investigate if acceptable turf quality can be achieved by applying different mulching materials after soil remediation and reseeding perennial ryegrass on a cool-season lawn subjected to diesel and hydraulic fluid spills.
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