2 Feb 2000
by Kate Melville
Most American gardeners spend lots of time trying to eliminate crabgrass when perhaps they would be doing a great service to promote its spread. Respect for this 'weed' is overdue according to University of Arkansas (UOA) researchers Greg Thoma, Craig Beyrouty and Duane Wolf whose work indicates that crabgrass may be useful for cleaning soil heavily contaminated with petroleum.
Oil contamination of soil is a big environmental problem in many parts of the world and there are few low cost remediation options available. The most obvious contamination has been at old wellheads where the ground is a hard, black expanse where nothing much will grow.
In areas like this most oil is actually quite near the surface and arguably not an imminent threat to the environment. So if you rule out traditional remediation then your options are pretty limited, and this is where crab grass and phytoremediation comes into its own.
Phytoremediation is a form of bioremediation that uses plants to reduce or eliminate the hazards by enhancing the naturally-occurring biological processes that cause oil decomposition.
The downside to phytoremediation is that it is slow. The upside is that it's low cost and requires next to no maintenance. The UOA study evaluated germination, survival and growth of five plant species in crude-oil contaminated soils. The species were:
Bermuda Rye Fescue Crabgrass Alfalfa
In addition the effects of several soil additives were examined. These included:
Biosolids from paper production
Sawdust (from hardwoods).
The study is part of Remediation Technologies Development Forum Phytoremediation of Organics project and used twenty research sites spread across America from Alaska to Arkansas.
"Although some models already exist, they are all intended for use with mobile contaminants such as heavy metals, TNT, or pesticides," noted Thoma. "Oil and many other contaminants are immobile and cannot currently be modeled accurately."
So if your neighbours complain about the quality of your lawn just respond by asking were they aware of potential oil contamination and that crabgrass is the best way to fix it. This will:
a) send them into a frenzy of expensive soil tests;
b) see them dig up their lawn and replace it with a lovely carpet of crabgrass.
As the late Quentin Crisp said, "Don't try to keep up with the Jones, drag them down to your level"! This applies to crabgrass lawns as much as anything else.