The home gardener or landscaper is at a disadvantage unless he or she has, literally, done the groundwork. That means fortifying and building up the planting soil with humus such as compost and peat moss and with the essential elements nitrogen, phosphorus and potassium, found in commercial fertilizers.
But the landscaper who wants to get the most out of those expensive trees and shrubs also will investigate whether the soil needs treatment for alkalinity or excess acidity—or whether, in some cases, he needs new soil.
Those $2 words, alkalinity and acidity, and the related symbol, pH (hydrogen ion activity), place this story in peril of sounding like a high-school chemistry course, so “sweet” is hereby substituted for alkalinity, “sour” for acidity and pH is discarded, except to note that soil is measured on a pH scale and if your soil scores 7 on that scale, it’s neutral.
Many well-meaning gardeners apply regular doses of ground limestone—a sweetener—to their lawns and gardens, in the belief that it will improve the soil. Unless the soil is fairly sour, it actually may be detrimental, since most plants grow best in a slightly sour or neutral soil.
A soil test is the way out of this dilemma, and is particularly important where major landscaping projects— such as a new lawn or a large vegetable or flower garden—are contemplated. In the case of these big projects, bringing in new topsoil may be a lot cheaper and easier than attempting to improve poor soil with additives.
Complete soil testing can be a do-it-yourself job. Kits are available for a few dollars but good ones are in the $20 to $50 range. The easiest way is to use the expert and inexpensive services of the Agricultural Extension Service in your county.
To get the most out of soil testing, and remove much of the element of chance from landscaping and gardening, several samples should be taken—one in the vegetable garden, a sample from a couple of points in the lawn, one from the area where fruit trees are grown, etc. Since testing is usually necessary only every four or five years, the cost is a real bargain.
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Ground limestone—never slaked lime or quicklime—is used to correct sourness in soil and aluminum sulphate or sulphur to reduce sweetness. Soil testing, however, also will determine the correct fertilizing needs in terms of nitrogen, phosphorus and potassium. The payoff here may be in hard cash as well as better plants, since either too much or the wrong kind of expensive fertilizer may be being used by haphazard gardeners.
While 5-10-5 (the numbers indicate the percentage of nitrogen, phosphorus and potash) is a good general fertilizer for many plants, lawns may require something much higher in nitrogen, such as a 24-4-4 formula. But only a complete soil test can determine the correct formula for a particular area.
If most of your plants are doing well and the complete test sounds like too much trouble, you can conduct a simple checkup for a few cents by buying a piece of neutral litmus paper at a drugstore. Press a bit of the paper against some moist soil after a rain—if the paper doesn’t change color, the soil is neutral; if the paper turns blue, the soil is sweet; if it turns pink, sour.