How to Develop a Good Garden Soil

Most people who buy a city lot, choose it for the appearance and convenience of the house; the soil of the lawn and garden is secondary. In some of the new suburbs the soil may be simply a solid mass of the cold Champlain Sea clay so common to this region, or it may be coarse sand from the Ottawa esker which crosses Ottawa South, the sand-pits along the Rideau River and the Merivale road. The sand is easier to handle but you are more fortunate to have the clays.

Regardless of the text book purchased most authorities speak of plant needs in terms of water and nutrients and omit the key element of aeration. This need for aeration is best shown by the orchids of the tropical jungle. Below the second or third layer of tree cover in the dusky steaming jungle many orchids grow on tree limbs, not as parasites, but true plants with their roots exposed to the moist, warm jungle air. Our northern plants grow best where their roots are in a soil-moisture chamber rather than in the open. They do not do well in water unless it is highly aerated, nor will they grow where it is dry. Thus, plants require a high water table which will permit capillary action to bring moisture up to the root hairs, and loose crumbly soil which will provide ample aeration. Nutrients will be mentioned later.

The ideal combination would be a clay subsoil to keep the water table high and above that a rich loam well filled with organic material. Unsuitable situations would be a solid clay soil which may be a gooey wet mass with no drainage, clays hard as a brick or a deep sand with the water table so low that the lawn or garden requires continuous watering. Almost as serious, as your author knows from sad experience, is either a sandy or stoney subsoil which provides excessive under drainage. An upper layer of rich loam is satisfactory only during a year of heavy rainfall if there is excessive under-drainage.

Since lots are not purchased for their soils, it is necessary to make the most of what is there. In the author's case, the only cure would be to bulldoze the rich topsoil to one side, add a clay or heavy loam base and then push the topsoil back again. This hasn't been done because of the perennials and shrubs already planted; yet it is the only final solution to the problem of excessive drainage.

If the soil is deep sand, the problem is the same as the author's. A heavy subsoil is required about eighteen inches to two feet down, and this should be arranged before the shrubbery, perennials, plants and lawn have been planted. Placing a few inches of topsoil over the sand will create a condition like the author's and cause trouble whenever there are watering restrictions.

If the subsoil is a loamy mixture of clay and sand, and light sandy soil has been used as the final fill, do not be discouraged. A generous mixture of organic peat, peat moss, and particularly manure will add the needed organic matter and tend to. hold moisture in the upper layers. The light soil guarantees the necessary aeration, the heavier subsoil will keep the water table high, and the organic material will absorb the water brought up by capillary action. A sandy topsoil is not a disadvantage if the water table is reasonably high.

Heavy clays seem the most discouraging, but given time, patience and plenty of hard work, they are the most satisfactory. If the garden area is in a hollow it may require tile drainage to remove excess water. The next step is to work organic material into the upper soil layers. One gardener who grows excellent flowers and vegetables in what was a most forbidding clay, had the city dump leaves on his garden for several years. Each year he covered his garden with leaves to a depth of about a foot and dug them in to a depth of almost ten inches. When his topsoil became friable and crumbly, he increased the depth of digging to about twenty inches and then added more leaves and manure to the upper layers. Now his garden is no longer a hardbaked forbidding clay, but a rich loam which grows most remarkable vegetables.

Some mention should be made here of hoeing, since there are now so many arguments for and against the practice. Hoeing does not increase fertility. It does, however, prevent the growth of weeds which are competing for soil nutrients, and what is seldom mentioned hoeing provides a loose dry surface layer which increases the soil aeration. Also, being very loose, the hoed top layer reduces capillary action near the surface and provides an insulating blanket which prevents excessive soil temperatures and moisture evaporation. Hoeing too close to plants will cut the root hairs and reduce the amount of water and nutrients available to them. But, if the principles behind hoeing are understood, it can be most helpful. On the other hand, if the soil is of a crumbly texture which provides both moisture and aeration, it is possible to use weed retardants and avoid the risk of destroying roots by hoeing. To hoe or not to hoe depends on the garden soil and on the gardener.

So far no mention has been made of nutrients. Canadian soils are almost all glacier-borne from distant regions so few originally contained too much of one chemical or were completely deficient in others. But many of the chemicals are in a form unavailable to plants. This is where organic material rich in soil bacteria can help. Manure, even fresh manure has a very low chemical value but its bacteria tend to reduce soil chemicals to a form available to plants. Thus its garden value is high since it adds both organic material and bacterial action.

If the analyses of soil samples show chemical deficiencies, do not hesitate to add what is necessary. Vegetables and perennials are a serious drain on the soil nutrients, so both manures and chemical fertilizers are required even in a garden with a balanced combination of soil and organic material.

As a final warning, be careful with chemical fertilizers and do not add too much. In other words, follow the directions. Moisture and the soil nutrients dissolved in the moisture enter the plants by osmosis, or the action by which a dilute mixture will move through the root -hair walls toward the stronger chemical solution inside. If the solution outside is stronger than that in the root hairs, the action is reversed and the plants die from drought or as most gardeners say "by burning".

Obviously the soil and plant nutrient processes are not as simple as this short description implies, but if these simple rules are followed excellent gardens and lawns will result.

Please contact the OHS or the author if you wish to republish these articles. © Ottawa Horticultural Society

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