Aussies' answer to sandy soil

ALONG one side of the house John Ward built here last year, there is an open patch of ground that until very recently played host to concrete blocks, scaffolding, and other construction items. Now this somewhat abused piece of ground is to become a garden, the first at the new home. It will require all the start-up preparation common to most new gardens - plus a whole lot more.

The major problem associated with this particular site is excessive leaching - water filtering down quickly through the soil. It is due primarily to sand that could go as deep as 30 feet, say extension officers in the region.

Obviously, getting sufficient air to the roots will prove no problem. Getting enough moisture to stay where the roots can get it certainly will be.

So Mr. Ward is turning to a solution that, as best he knows, was developed by some Australians on an agricultural project in the South Seas. It involves ordinary polyethylene plastic sheeting. Since Ward's problems are by no means unique to his area, the South Seas technique is worth a closer look:

1.Dig out a trench, as wide and long as you want the bed, to a depth of 21/2 feet. If there is any semblance of top soil be sure to keep it separate from the sand.

2.Line the bottom of the trench with plastic sheeting, turning up the sides six inches to form a shallow water-retaining trough. Place a thick layer of newspaper over the plastic to prevent any sharp stones from puncturing the plastic.

3.Add peat moss, shredded leaves, straw, ground-up newspaper, and any manure you have to some of the sand removed from the trench. Add at least one measure of organic materials (higher if you have them freely available) to two measures of the sandy soil. 4.Mix up the ingredients thoroughly and return to the trench, scattering such top soil as might exist over the top.

5.During the first season while the organic matter is decomposing, it might be well to feed plants with liquid fertilizers every two weeks.

The beds work like this:

Water and nutrients applied to the surface percolate down and are retained in a pool some two feet below. This artificial water table keeps moisture within reach of the roots during dry periods and also enables some moisture to percolate back up to the surface. In heavy rains, excess water simply overflows the plastic trough and drains away through the sand.

Are these man-made water tables too close to the surface?

Hardly. In Holland, many of that country's famous bulb fields have a permanent water table little more than 12 inches down.