Taking a soil sample and sending it to a soil lab is a fundamental first step
in achieving better gardening results!
When you really get serious about growing a nicer lawn,
flower bed, vegetable garden or landscape
beds, a soil
test will be at the top of your priority list. Adjusting soil pH and
balancing nutrients before planting
makes good sense, especially since some fertilizer is best incorporated into
the soil with a rototiller prior to planting. During the decades we were
landscaping we always used the soil
testing services of the Merkle Lab at Penn State, mailing soil samples into
the lab several weeks before we needed the results.
SOIL TEST RESULTS
Soil test results include
basic deficiencies and what steps are recommended to correct them in
gardens, lawns and landscape beds.
For Do-It-Yourselfers, soil test kits were available for $12 in 2011 from
the local Penn State
Extension offices. In western Pennsylvania, there's an Extension Office in Washington, PA
another in Pittsburgh (you'll find their contact information at the bottom
of this page).
Soil sampling 'plugs' sent to the soil lab should be longer
than the ones pictured above, 4-inches is about right
for lawn soil samples. Soil should be dry and have
stones and organic debris removed prior to mailing
to the soil lab.
HOW TO TAKE A
included with the soil test kit point out that it's important to get a representative
sampling of the growing area. If there are drastically different types
of areas, you should send more than one soil sample to the soil lab.
testing a home lawn, we use a commercial soil probe, which pulls a soil
"plug" approximately one-inch in diameter. These soil cores are taken from 10 to 20
locations in your landscape or
lawn, allowed to air-dry, then mixed together and packed for shipment to the soil lab.
Results follow in 3 to 4 weeks when we receive your soil test report back from the
Soil Lab. At that time, we can provide cost estimates and timing for addressing any
Repeat soil testing every 3 to 5 years.
INTERPRETING SOIL TEST
There are three
major areas we focus on in the report:
Soil pH -
This determines if lime needs to be applied, and if so, how much. We also check the Mg/Ca
levels to determine what type of lime would be best - calcitic or
dolomitic. (also see Soil pH)
- Soils in S.W. Pennsylvania are often low in Phosphorus, and it is critical to have this
major nutrient at its optimum level when establishing new turfgrass, or hoping for the
best flower blooms.
Another major nutrient that needs to be optimized for the best growth from turf, flowers
or woody ornamentals. (also see Fertilizers)
HOW TO CORRECT
Depending how much lime is
required, it may be necessary to split the amount into two applications. It is best
not to apply more than 50 lbs. of calcium carbonate per 1,000 square feet per year.
While fall is often the recommended time for applications, we successfully apply our
pelletized lime all year.
and potassium deficiencies can be corrected with an application of 0-20-20, or separate
products like 0-20-0 or 0-46-0 (for phosphorus) and 0-0-60 (for potash).
CAUTION should be exercised when
applying potash products, since they have a high salt index and can burn foliage!
You might also find a
"winterizer" fertilizer that is high in potash and will help correct a
deficiency. ALWAYS READ THE LABEL on the fertilizer bag for specific
instructions on its proper use.
Sample of a soil
test report from Merkle Lab
(click image to enlarge)
Laboratory at Penn State
test report shows 3 important sections:
Nutrient Levels -
The bar graph (with "X's" extending across the page) shows Soil pH, Phosphate,
Potash, Magnesium and Calcium levels. In this particular report, all the levels are
within the "optimum range", except for Calcium which is just into the
Home Lawn - This middle section provides specific recommendations for applications.
(The report would be slightly different if you had marked "Establish new lawn"
instead of "Maintain home lawn")
Results - These are the
specific numbers that were translated in the bar graph above. An additional number
of interest is "CEC" (cation exchange capacity) which indicates the soils
ability to hold nutrients.
This established home lawn in
Upper St. Clair township isn't in need of any corrective applications at this time.
If someone had "guessed" and applied lime, the calcium level would have been
pushed further into the excessive range, and the pH would have become too
alkaline. (The pH is currently 7.4, and would ideally be 6.5 to 7.2)
Natural rainfall in the Pittsburgh area will lower this pH into the optimum range within
a few years. Therefore, other than ordinary lawn fertilization, the next thing this
lawn will need nutrient-wise, is another soil test in 2004.
Science of Soil