Do You Know Your Garden Soil?

| 4/24/2013 12:49:39 PM

Tags: Garden soil, pH, Acid or alkaline, Sandy soil, Clay soil, Silty soil, Karen Newcomb,

Karen NewcombMost garden soils are far from perfect, yet many gardeners plant without making any improvements and then wonder why their vegetables are far from ideal.  If you look in your own garden, you’re likely to find clay, sand, and silt.

Clay soil is composed of fine, flat, waferlike particles that fit together tightly and take in water slowly.  Chemically, clay is chiefly silicon and aluminum, with small amounts of sodium, magnesium, iron, calcium, and potassium.  When you sprinkle a clay bed, the water runs off instead of sinking in.  If the clay particles do absorb moisture, they hold it too tightly for the plants to use much of it.  When it’s rubbed between the fingers, wet clay soil feels smooth, soft, and slippery.

When clay dries, it often has the consistency of brick.  The particles are so compressed that there isn’t any space for air to penetrate and plant roots have great difficulty forcing their way down.  Plants grown in untreated clay soil are often stunted and have pale green or yellow leaves.

Sandy soil is the opposite end of the scale.  It is lighter than clay but has particles 25 times larger.  While sand is easy to dig in, it has almost no capacity to store water, which moves freely through the soil and quickly leaches out the nutrients.  Sandy soils warm up faster than clay soils and reflect a considerable amount of heat.  Most sandy soils, however, contain enough clay and silt to retain water and nutrients.

Sandy soil rubbed between the fingers feels grainy and gritty.  Plants grown in sandy or gravelly soils frequently have yellow or pale green leaves.

Silt falls somewhere between clay and sand.  It consists of medium-size gritty particles that pack down hard almost like clay and is seldom very fertile.  If silt topsoil covers a layer of heavy clay, the plants may be stunted because the clay layer traps and holds water.  Silty soil rubbed between the fingers feels slippery but has a grainy texture.  Plants grown in silty soils often have pale green or yellow leaves.

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