Living Resources Company
- BUGS Parent Company
Providing organic horticultural services for the greater Sacramento
How to take a
soil sample for analysis:
Soil Sampling Principles:
Soil sampling is used to determine the nutrient supplying
ability of the soil. This information is required if you are to determine what fertilizers
and forms of organic amendments need to be supplemented. The accuracy and usefulness of
your soil test depends on the soil sample submitted. Care must be taken to submit a good
sample for the test results to be reliable.
There are several tools that can be used to select soil to
be tested. Soil augers (also known as soil sampling tubes) are the best tools for the job.
They are made of stainless steel or are chrome plated, expensive and usually must be
purchased from mailorder sources (AM Leonard Inc., PO Box 816, Piqua, OH 45356,
513-773-2694; Ben Meadows
Company, 3589 Broad Street, PO Box 80549, Atlanta, GA., 30366, 800-241-6401; Forestry
Suppliers, Inc., 205 W. Rankin St., PO Box 8397, Jackson, MS. 39204, 601-354-3565). Soil
augers are not practical for homeowners but are required equipment for horticultural
professionals. If a soil auger is not available stainless steel spades or garden trowels
can be used. A suitable container is needed to place the soil as it is being gathered. A
clean plastic bucket is sufficient. Galvanized, soft steel or brass tools will contaminate
the sample with trace minerals such as zinc. Hands are not proper sampling tools. They
must not come in contact with the soil or the sample will be
contaminated. Using these tools will result in inaccurate test results and improper
fertilizer recommendations. Soil cores from each management zone can be placed in
separate, clean plastic or paper containers. Then thoroughly mix the soil in each bag.
Again do not touch soil with your hands as this will contaminate the sample and result in
Before you go out and collect soil, examine the ground to
be analyzed. Areas that have different soil types should be sampled separately. For
example, garden soil that has been heavily amended for years should be sampled separately
from the lawn. Unrepresentative soil such as low marshy areas and soils around buildings,
near roads, and fences should be avoided altogether (unless you specifically desire a
separate sample for these areas). Areas that require different management and fertilizers
should be noted and sampled separately. Soil around acid loving plants (or other specialty
planting areas) should collected and tested individually since they are managed
differently than the rest of the landscape and comprise a separate zone. The landscape
should be mapped out showing where any different management zones are and where
the separate soil samples will be taken from.
Gathering the soil properly is the key to soil testing. The
best laboratory in the world will give you faulty advice if the sample was collected
improperly. Care must be taken when sampling soils so as to make them a representative
sample that has not been contaminated. The soil will be easy to sample if the
moisture content is correct. Dry
soil is difficult to probe. Wet soil will become compacted as you walk on it. Soil should
have the moisture content desirable for tilling. Wet soil to be tested will need to be air
dried if it is to be sent for testing or mold will develop.
Each management zone to be tested should have ten to twenty
cores taken randomly from throughout the sample area. If a soil auger is not available
take your shovel or trowel to cut and remove a V section of soil (see diagram). Then take
a 1/2 inch slice out of the side of the hole. After taking the sample replace the V of
soil in the hole. The depth of the sample should approximate the zone of major water
absorbing roots by the plants to be grown in the area. Examples of sample depth are
lawn - 6", shrubs and trees - 10" (taken at the drip line - outermost branches)
or the depth of cultivation in annual beds. All cores from each zone should be taken at
the same depth. Any organic matter or debris on the surface of the soil (i.e., mulch,
surface litter, or thatch) should be removed from each core or slice before it is
deposited into the sampling container. Organic material on the surface is not part of the
soil and should not be included in the soil sample. Doing so would give you faulty
readings. After taking 10 to 20 randomly located cores the sample should contain
approximately 1-1/2 cups of soil for each zone. Mix each sample thoroughly.
Place the soil in the sample bag provided. Note the
identification (location) of the soil, the sample number (if submitting more then one
sample), and your name on the soil sample bag. Fill out completely the information sheet
provided. The more information you can provide, the better the recommendations will be.
For the most accurate results (especially for nitrogen level readings) send the sample to
the lab as quickly as possible.
Soil tests should be a major determining factor when
formulating fertilizers. It is the only way to know what needs to be supplemented. If the
recommendations are accurate and followed, your plants will benefit tremendously. The soil
will be more fertile with more beneficial microorganisms. This will, in turn, grow
healthier pest resistant plants.
Factors that create inappropriate test results:
1. Improper sample depth.
2. Combining soils from different management zones or of different types.
3. Not utilizing enough cores per sample.
4. Not removing surface organic matter.
5. Soft rocks being included in the sample.
6. Fertilizer or other materials applied to soil just prior to sampling
(not enough time for it to become incorporated).
7. Drought conditions not allowing fertilizers to become properly incorporated.
8. Artificially drying the soil sample.
9. Use of contaminated containers or equipment.
10. Improper sample identification.
What to send:
Mail the soil sample, completed soil information sheet, and
a check or money order for $110.00 made payable to:
P.O. Box 76,
Citrus Heights, CA. 95610.
Expect the results of the soil analysis within 8 to 10
weeks (may be faster depending of time of year). The results will be accompanied with
extensive recommendations on how to properly amend your soil organically written by BUGS
staff soil scientists.