What Type of Soil Holds the Least Amount of Nutrients?

Types of Soil

• Soil consists of different sized particles called clay, silt and sand. The texture of your soil depends upon how much of each of these particles is present. Clay is the smallest particle, and soil with a lot of clay in it is referred to as heavy or sticky. This type of soil drains more slowly and retains nutrients more effectively. Silt is the next largest particle and tends to feel smooth and powdery. Silty soil is still fairly fertile. Sand particles are the largest and feel rough when rubbed between your hands. Water runs right through sandy soil, as do nutrients, which means that, of all the soil types, sand holds the smallest amount of nutrients.

Soil Test

• You can perform a test to determine the clay-silt-sand ratio of your soil. Collect samples from your garden by digging down about 6 inches with a trowel and placing a scoop of soil from several different areas into a bag. Spread the soil to dry for a few days, and then sift the soil to remove rocks and large chunks. Place the sample in a quart jar with a screw lid, and add 1 tablespoon of powdered dishwasher detergent -- this helps the particles to separate. Fill the jar with water, put on the lid and shake the jar for about three minutes. Let the jar sit for several hours until the contents settle into layers. Sand is the heaviest, so it will settle to the bottom, the silt layer will be in the middle and the clay will be on top. If the sand layer is the thickest in your sample, your soil is mostly sand and will not hold nutrients very well.

Weed Signals

• You can also get a clue as to what kind of soil you have by the weeds that grow there. Sandy soils that do not hold nutrients well often grow cornflowers (Centaurea cyanus), yellow toadflax (Linaria vulgaris) and arrow-leafed wild lettuce (Lactuca pulchella). If you find many dandelions (Taraxacum officinale), lamb's-quarters (Chenopodium album) and burdock (Arctium minus), that means that your soil is very fertile.

Improving Sandy Soil

• It took a long time for your garden soil to form, so plan to make your soil improvements over several seasons. One way to encourage sandy soil to retain more nutrients is by adding compost. Piling dry leaves or straw on the garden in the autumn and turning it into the soil in the spring will improve fertility. You can also grow green manure crops such as annual ryegrass (Lolium multiflorum Lam.). Plant it in the fall, and turn it under two to three weeks before you begin to plant in the spring.