In a 2014 study, scientists again compared the damage caused by a petroleum-based oil, a vegetable-based oil and a synthetic oil. Again, synthetic oil reduced the extent of turfgrass damage compared to petroleum and vegetable oils. Researchers hypothesize this is due to differences in properties like viscosity and density, which can affect the persistence and dispersion of hydraulic oil in the rootzone (Berndt et al., 2017).
So far, all the research discussed has been on warm-season grasses. A study conducted at Penn State University from 2010 to 2012 had the goal of evaluating hydraulic oil leaks on cool-season turf. In their study comparing five different types of hydraulic oils (one petroleum, one vegetable, two synthetic and one diester) they found all hydraulic oil treatments killed ‘A-4’ creeping bentgrass within two weeks (Kaminski et al., 2019). However, another question this study sought to answer was how remediation practices can mitigate damage. They came to a similar conclusion as Berndt did, that synthetic polyalkylene glycol hydraulic fluid causes less damage to turf, but only if certain remediation practices are performed after a leak.
What Should You Do After a Leak?
Theories about how to respond to a leak are wide-ranging and full of misinformation. When a post appears on social media from an anxious turf manager looking for advice following a hydraulic leak, the solutions offered can run the gamut. Researchers looked at some common remedies to see if any make a difference.
Flushing with water and/or detergents
Drenching the leak with water hoping to flush the oil through the soil is one of the most common responses. Unfortunately, studies show that this approach does not reduce damage or shorten recovery time (Berndt et al., 2017; Kaminski et al., 2019). Adding detergent to a water flush is sometimes espoused as a remedy, but that has been shown to actually increase the extent of injury by dispersing the oil further (Berndt, 2018). The only exception to this was with synthetic oil, specifically polyalkylene glycol fluids. Penn State’s research indicates applying a detergent and water solution to this type of hydraulic oil leak, brushing it in and then rinsing, eliminated turfgrass injury after four weeks. It’s important to note this detergent, brushing and rinsing remedy did not work on petroleum- or vegetable-based hydraulic oils.
Other remedies
Other products often used in an effort to mitigate damage or speed up recovery include wetting agents and other surfactants, activated charcoal, clay materials, kitty litter, saponifiers, emulsifiers and organic amendment products. Cultural practices including aeration and topdressing, scalping the turf and verticutting are sometimes promoted as ways to speed up recovery as well. There is no research that shows any of these approaches consistently mitigate damage or speed up recovery.
The fastest way to recovery
The oil causes the damage, and until it’s gone recovery will be slow. How slow depends on factors like soil type, time of year, plant species, overall plant health and your climate. For example, damage from a hydraulic oil leak on a perennial ryegrass/Kentucky bluegrass tee in New Jersey in November will likely be visible until the following spring if recovery is left to Mother Nature.
Although it’s labor-intensive and time-consuming, stripping the damaged sod, removing and replacing the contaminated soil, and sodding the area with new grass is probably the fastest way to repair hydraulic oil leak damage. A hexagon turf repair tool or other type of plugger can be used to repair damage from smaller leaks. Be sure to dispose of the contaminated sod, soil or plugs in the same way you would any other oil-soaked material.