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Invisible Forces in Your Garden

Test your soil to put them to work

Horticulture is a science, not a guessing game.
    I can remember my pipe-smoking, tobacco-chewing grandfather putting garden soil in his mouth to taste if it was sweet or sour. I was impressed at the time, but looking back on his method of testing soil, I know it would have been impossible for him to make any determinations of the pH or of nutrients by taste.
    Just as doctors rely on blood tests as guides to their patients’ health, in agriculture, we rely on soil test results. Soil testing supports both the health and nutrient value of plants. A deficiency of one or two essential soil nutrients reduces not only yields but also the level of nutrients within plant tissues that will be ingested by humans or animals. Soil that is deficient in zinc, copper, iron, magnesium, calcium, etc. will produce plants that are equally deficient, which will have a direct effect on your health.
    If you have applied 10-10-10 fertilizer on your garden or lawn for many years, it is likely that your soil has too much phosphorus. That excess can, in turn, result in reduced crop yields and plants deficient in zinc, iron, copper and manganese. The excess phosphorus binds these nutrients, making them unavailable to the roots of plants.
    This is the problem farmers experience from repeated applications of chicken manure, which is rich in phosphorus. In that case, the excess phosphorus in the soil is making the soybeans or corn grown there deficient in essential elements. Humans or animals eating those grains will not get a nutritionally balanced diet.
    Too much phosphorus causes still more problems. When soil erodes and enters Bay waters, phosphorus attaches to clay particles. When these clay-laden soils penetrate silt fences and enter the Bay, the phosphorus is released, adding to the water’s nutrient-concentration problems.
    Another element, boron, is also secretly at work in your soil. If you are gardening in a sandy loam or loamy sand, boron deficiency is likely. Plants do not require much boron, but its deficiency affects yields and storage life. You have likely seen the result without recognizing it. The brown punky blotches you sometimes see beneath the skin of an apple tell you that the fruit was grown on boron-deficient soil.
    Without soil testing, you won’t know the invisible forces at work in your soil.
    I can now give you a choice of two laboratories for your soil testing:
    • A&L Eastern Agricultural Laboratory, now known as Waypoint: www.al-labs-eastern.com (804-743-9401; 7621 Whitepine Dr., Richmond, VA 23237).
    • AgroLab, Inc.: www.agrolab.us (302-566-6094; 101 Clukey Dr., Harrington, DE 19952). Request a soil-testing kit, including instructions on how to take qualitative soil samples.
    Include my e-mail address (dr.frgouin@gmail.com) on the information sheet to have results sent to me for interpretation. Include your own e-mail address as well so I can forward you my recommendations.
    Good recommendations depend on a good sample. To represent your current soil conditions, take at least five core samples to a depth of six inches in six different locations in your lawn or garden. Mix the core samples thoroughly in a clean container. Remove about a cup of soil for testing. Spread the sample on a clean piece of newsprint to dry overnight before mailing. On the form, identify what’s to grow in that area. Results are typically returned within a week.


Ask The Bay Gardener your questions at DR.FRGouin@gmail.com. Please include your name and address.