| Gather soil samples for a laboratory soil test (from top) by taking a combined sample from several locations within the area (turf, flower bed, or vegetable garden). |
"Be it deep or shallow, red or black, sand or clay, the soil is the link between the rock core of
the earth and the living things on its surface. It is the foothold for the plants we grow." – Roy
W. Simonson, USDA Yearbook of Agriculture, 1957.
Gardeners realize plants need the right soil conditions to grow and thrive. But most of us have only a
general idea of what soil types and nutrient levels are in our flower beds, vegetable gardens, or lawns.
We add a little more mulch each year, throw in some compost or commercial fertilizer, and hope for the
best. Fall is a good time to correct the error of our gardening ways.
Soil consists of sand, silt, and/or clay particles. Sandy soil has coarse particles, clay very small
particles, and silt particle sizes are between sand and clay. Loam is some combination of sand, silt,
and clay. Each of these soil textures dictate how well our soil will drain, how much organic matter it
will hold, and how much air the soil will have for good root growth. Soil texture also affects the soil
pH (the acidity or alkalinity of soil), how well the soil retains nutrients, and how workable the soil
will be.
| Then perform the ball squeeze test or soil ribbon test. |
For example, clay soils hold nutrients but are hard to work, and plant roots sometimes have difficulty
penetrating the clay. Sandy soils have good drainage and aeration, are easy to dig or till, but do not
retain nutrients well. Loam is considered to have the most desirable characteristics of sand, silt, and
clay, and we are envious of the fortunate gardeners who have it.
Since some plants have specific soil requirements to grow and thrive, gardeners need to know what kind of
soil texture they are working with.
A couple tests which can be done by most average gardeners give a rough idea of soil texture. There are
field tests that consist of making balls and ribbons of moist soil in ones hands and observing how they
feel and look. Another field test is to shake up a soil and water mixture in a glass jar and let the
soil particles settle out. The sand, silt, and clay particles stack in neat layers. Measure the height
of each layer, calculate the percentage of each layer in relation to the whole, then go to a chart to
find out whether the soil is loam, sandy loam, or another soil type.
Detailed descriptions of these tests are found in "Soil Texture" by Cornell University
Cooperative Extension Service; and in Colorado State’s "Estimating Soil Texture: Sandy, Loamy or
Clayey?" (See links below).
There are also quick and easy ways to sample for soil nutrients, but they are not free. For instance,
there are numerous testing meters and test strips sold by garden supply stores and on-line vendors. Some
meters are for nutrients only, some for pH only, and some do both. These meters provide some idea of the
main soil nutrients and the acidity or alkalinity of the soil. The most accurate meters are the most
expensive.
Soil texture and nutrient tests discussed so far are fun to do and give a general picture of our soil.
But the most accurate results are from a reliable soil testing laboratory. The Wood County OSU Extension
Office provides a kit from Pennsylvania State University for this purpose. For $10 one receives a mailer
and a kit explaining how to take soil samples.
| Clay, silt, and sandy soils behave differently, or finally the jar test. Sand takes minutes to settle out, silt takes hours, clay particles take days. |
Soil sample instructions that come with the sampling kit are easy to understand. Just take a composite
sample from a dozen or more places in the area you want tested and send it in using the pre-addressed
mailer. The resulting report will give levels of key nutrients and a chart that shows whether these
nutrients are too low, optimum, or too high.
The report also recommends what type fertilizer to use and how much. Optional tests are available for
soil texture, lead, mercury, and other soil components for an additional fee per item. Lab results are
sent to the gardener and to OSU Extension so that we can discuss test results and recommendations with
an OSU Extension Agent.
To obtain a kit, contact OSU Extension at 639 South Dunbridge Road, Suite 1, Bowling Green, Ohio 43402.
Call (419) 354-9050 during business hours of 8:30 a.m. to 4:30 p.m., Monday through Friday.
By using one or more of these tests, gardeners will better understand the "foothold for the plants
we grow."
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On the Net:
Soil test information
www.water.rutgers.edu/Rain_Gardens/factsheet29.pdf
http://cmg.colostate.edu/gardennotes/214.pdf
