I'm told I need to aerate compacted soil by drilling holes around the root zone of affected trees. Can anyone recommend a 2 or 3" by 24" drilling auger (type / brand & where to purchase)that would fit on a 1/2" drive drill?

Reply to post by Matt M, on July 16, 2002 at 11:23:03:

Drilling holes is one way to relieve compaction. Downsides are cutting roots with the auger (Bad!) and glazing the hole surface, which inhibits the air, water and nutrient movement that was the purpose.

Swinging a miner's pick into the ground does less damage to roots because the tip is much narrower than an auger. Pulling up on the handle cracks apart the soil, increasing aeration.

ps--a 1/2" drill ain't big enough anyway.

Radial trenching also works well. See www.isa-arbor.org, Consumer Info, Treatment...brochure for details on aeration. Consider calling in a local arborist, whose advice might save you money.

Reply to post by Matt M, on July 16, 2002 at 11:23:03:

If the soil is badly compacted, drilling holes will help a bit with aeration. It does run the risk of damaging roots, probably more risk of damaging the equipment operator if not careful.

The problem with compacted soil is that pore spaces have been crushed, and air and water can't move into and through the soil to the roots. Treamtnet must be directed at this, and drilling holes can help to some extent. Most compaction is close to the surface, so going a few inches deep is enough to help the problem.

A one- or two-inch diameter auger is best, to minimize root damage. Also stay well away from the base of the tree- no closer than three or four feet for smaller trees, more if they are over 24 inches in trunk diameter. Make the holes about 2 feet apart on a grid pattern or in concentric circles, and at least 8 inches deep. The holes should be backfilled with a very loose organic soil or well aged compost. This allows the air and water to move, and also provides organic matter.

There is an easier way, by emmploying a lot of cheap help. mulch, Mulch, MULCH!! (3 inches deep, and NOT against the bark of the trunk.) Spread the mulch over as large an area around the tree as possible, the more are covered the better. Then hire (I mean buy) a pint of earth worms (nightcrawlers, not red worms) and set them to work in the mulch bed. They are the bulldozers of the rhizosphere, and will till the soil quickly and efficiently, and more effectively than if you drill a lot of holes. The mulch provides a great habitat for them, and eliminates grass competition. You will be surprised at the difference in growth afterward.