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Once again, clover is a good thing

Correction: Due to incorrect information provided by a source, a June 24 article on clover incorrectly identified the active ingredient in Roundup, an over-the-counter weed killer. The active ingredient is glyphosate.

Ever heard the old saying about a lucky rabbit's foot not being very lucky for the rabbit? Well, the clover on your lawn -- both the three-leaf and the supposedly charmed four-leaf varieties -- probably knows exactly how that bunny feels.

Once a prized ground cover and grazing material for animals (clover contains more protein than other grasses), clover was no match for the marketing forces of lawn chemical companies who rebranded it as a noxious weed in the years after World War II.

But that thinking is slowly changing, lawn-care specialists say.

In the 1940s, clover was considered an acceptable part of the suburban lawn. It made sense, because clover and most lawn grasses enjoy a good relationship. Unlike grass, which greedily sucks the crucial nutrient nitrogen out of the earth and can reduce rich topsoil to moon dust in a matter of years if left to its own devices, clover takes its nitrogen from the air.

The clover fixes the nitrogen from the air in the soil around it, where it can be used by the grass growing nearby. When it dies or is cut and mulched, clover becomes a nice bit of nitrogen-rich compost, just like other grass clippings.

Then, in the late 1940s, along came 2,4-dicholorophenoxyacetic acid , a chemical weed killer that was hailed as a breakthrough and became a component of herbicides ranging from the Vietnam War era's infamous Agent Orange to current popular home-use brands such as Roundup and Halts .

"Clover was part of the traditional lawn," says Bill Winter , the longtime lawn-care buyer at Russell's Garden Center in Wayland. "Then we started the whole better-living-through-chemicals thing. They discovered that the new herbicides also killed clover, so the herbicide had to be a good thing and clover became a weed."

Beyond putting nitrogen back into the soil, another benefit of clover is that it acts as sort of an "early-warning system" for potential lawn trouble, said John Packard , the owner of the New Hampshire-based Cockadoodledoo organic lawn-care company.

In healthy soil, most grass can out compete and control clover, but in depleted and nitrogen-poor soil, clover will gain the upper hand.

"When a lot of clover appears, you know your soil is in trouble," Packard said.

Clover is even a boon for those hard-luck bunnies.

Rabbits are so fond of clover, garden experts say, that if you determine where their dens are and grow a patch of clover between their homes and your vegetable garden, they'll never make it to your beans and carrots.