A Test To Determine Soil Type

All too often, gardeners try to guess what is in their soil and – guess wrong. The only way to be sure is to make a wash test. Light sandy soils that contain little clay are easy to test. Heavier soils with a high clay content are difficult because of the strong electrical attraction of acid clay particles for lime (there are alkaline clays but most are acid). The bond between clay and lime can be broken by adding 2 tablespoons of a common fertilizer (nitrate of soda) to the test.

To make the test: Begin with a clean half gallon mason jar or other round glass container. Add half a cup of soil to the jar and pour in enough water to half fill it. Screw the lid on tightly and swirl the water around rapidly for about a minute. Let it settle. Repeat this swirling several times. Next, allow the water to stand until it is clear. Clay particles are extremely fine and may take a week to settle.

When the water has cleared, the various sized particles will be in layers. On top will be the clay particles and on the bottom the larger bits of mineral matter such as sand and fine gravel. Between them, there is a layer of silt.

How do you recognize the value of natural soil? How do you improve it? The nutritional value of soil is hard to determine by casual inspection. A test must be made to determine it. However, dark soils usually have organic matter. A wash test as described above will tell a great deal about soil.

Are there special kinds of soil for different plants? Root crops require friable, light soils for best development. Crops with fine roots do better in coarse open soil, while coarse rooted plants grow better in more dense soils composed of finer particles.