Raised-bed gardening solves soil problems

Two friends of mine on opposite sides of the Atlantic -- in old England and New England, to be exact -- have identical soil problems: heavy wet clay that precludes most attempts at gardening until summer is well on its way.

In the past, I've sympathized with them both and have advised that they mix a lot of organic matter into the soil. However, I overlookd raised-bed gardening, a technique which I practice in my own back yard and which would be ideal for both of them.Thus, a leter to one and a phone call to the other have rectified the oversight.

The fact is, I have no drainage problems at all. If anything, my sandy soil drains too easily.There are other positive reasons for raised beds in my garden and it was only when I was contemplating some additional gardening on heavier soil elsewhere that I realized that drainage would be little or no problem if the beds were raised.

Raised beds, quite simply, are mounded-up garden soil. You can have them as narrow as a foot (for single-row planting) or as wide as five feet if you can reach in comfortably from that distance. These are some of the advantages of the raised bed:

* Drainage is improved because water from a heavy rain flows into the hollow paths. While this might make it mucky underfoot, it leaves the soil a whole lot dryer in the spring for early planting. Oxygen starvation is avoided in long wet spells.

* The soil remains sofeter because standing water does not compact it. Also, because the raised beds allow the soil to "give" on either side, root development is made that much easier.

* Raised beds warm up much sooner in the spring. At the Gardenay experimental gardens in Vermont, soil temperatures in the raised beds frequently are 8 to 10 degrees warmer than in the paths -- a big plus in colder climates, such as New England.

* Raised beds provide more gardening space. Once your garden soil has been made rich enough through the application of manures, composts, and other organic materials, roots can go straight down in the search for nutrients. This allows for more dense planting, hence more harvest per square foot. The fact that the raised bed has a curved surface also provides more square feet of planting space than a flat bed.

To make a raised bed, dig or till the soil over your entire garden. Now mark off your paths (say 18 inches wide) and, with a spade, spread the pathway soil on the adjacent bed. This way you not only raise the bed, increasing the depth of the topsoil, but you lower the path at one and the same time. If you have a tiller with a hillerfurrower attachment, it will do the job nicely.

In my garden, I use the hollow pathways as a depository for garden and other organic waste as it becomes available. As I walk along the paths all season long, this waste is mechanically broken down. At the same time it begins to break down biologically. By the end of the growing season the earthworms have worked it over pretty thoroughly as well. In other words, my long, hollow pathways double as compost trenches.

The next spring this compost is dug out of the plants along with a thin layer of newly created topsoil and spread over the beds. This way the soil enrichment process is continuous.