Soil Testing Equipment

Follow the specifc instructions provided by the soil testing lab you select.  The following guidelines will help ensure that a good sample is taken: Separate samples should be taken for distinct areas- front yard, back yard, vegetable garden, etc. The sample should represent  the soil in which the plants are or will be growing. Use a  spade or trowel to take 10-12 random samples across the area  of concern.  The samples are thin slices taken to a depth that  contains or will contain the bulk of the plant’s roots- 3 inches for turf; 6-8 inches for garden and landscape beds.  Mix together all of the slices in a clean bucket removing all rocks, debris, and
plant material.

Don’t send wet soil; you should not be able to squeeze water  from the sample. Send a minimum of 1 cup and a maximum of  2 cups of soil per sample.  If no kit is provided, seal the soil in a  zip lock bag or use the special soil sample bag provided by the  Maryland Department of Agriculture and Maryland Cooperative  Extension.  Forms for most of the labs can be downloaded from  their websites. Be sure that all of your contact information is on  the form and mail it back to the lab with the sample, check for  the correct amount, and suffcient postage

Soil test reports from all of the labs will provide a graphical representation of results- the level of various nutrients from your soil (low medium, high, excessive).  “Optimal” and “excessive” levels mean that the nutrient concentration in the soil is more  than adequate for optimum plant growth.  Adding more of that  nutrient will not improve plant growth and may have undesirable  effects on the environment.

Be aware that the specifc turfgrass fertilizer recommendations  you receive will not be identical to Maryland’s.  This is due to  differences in soils, climate, and and state water quality policies.   Always follow University of Maryland recommendations for applying the right amount of nitrogen for healthy lawns.  Go  to the “Publications” section of our website to download  the following fact sheets: HG 103, “Fertilizing Facts for
Home Lawns”; FS 702, “Lawns and the Chesapeake Bay” (has more detailed information on grasscycling, slow release  nitrogen fertilizers, and fertilizing responsibly); and HG 42,  “Soil Amendments and Fertilizers” (contains broad fertilizer guidelines for many garden and landscape plants).

Abbreviations and Terms Found in Soil Test

The labs listed in the chart provide defnitions and explanations  of soil sampling terms and concepts.  The list below will help you  better understand the soil test reports you receive. pH-  soil pH is a measure of a soil’s hydrogen ion concentration.  The greater the number of hydrogen ions the more acidic the soil.  The pH scale is 1-14. 

Soils with pH levels below 7.0 are considered acidic and soils with pH levels above 7.0 are  considered alkaline. Soil pH is a critical measurement for gardeners because it affects the availability of nutrients for uptake by plant roots.  Most garden and landscape plants grow best in soils with a pH of 5.5–7.0.  Certain plant nutrients can become  unavailable or excessively available outside this range, leading  to plant growth problems. But there are exceptions:  for example,  plants in the azalea and blueberry family grow best at pH 4.0-5.0.

Macronutrients: these are required in the greatest quantity by plants. Sulfur (S) is rarely tested because soils in Maryland are rarely defcient.  Nitrogen (N) is not usually tested because it is constantly changing.
P-  phosphorous
K-  potassium
Mg-  magnesium
Ca-  calcium

Micronutrients:  These important nutrients are required in  relatively small quantities.  Defciencies are rarely a problem in  Maryland soils, especially in the Central and Western regions.   Eastern Shore gardeners may want to be sure that boron is  included in the test they select.
Fe-  iron
Zn-  zinc
Cu-  copper
Mn-  manganese
B-  boron

Heavy metals:  excessive levels are a concern, especially in soils where food crops are grown and children play.  These elements can be a health hazard when 1)tracked into the house via shoes and tools, 2)ingested by young children, or 3)ingested from food crops grown in contaminated soil.  For more information on lead,
refer to Maryland Cooperative Extension fact sheet HG #18, ”Lead in Garden Soil.”
Pb-  lead
Ni-  nickel
Cd-  cadmium
Cr-  chromium

OM-  organic matter; includes living and decomposed plant and animal tissues (dead leaves, soil fungi, plant roots, etc.  Soil organic matter drives a soil’s biological and chemical processes.  OM test results are given on a weight basis. Usually a sample is weighed in the lab and then ignited to burn off the carbon compounds, leaving only the mineral soil.  The sample is reweighed to determine the OM%.   Gardeners who add lots of  organic matter to their soils may be surprised that the OM content is less than 5%.  This is because OM is lighter than mineral soil  and the measurement is based on weight, not volume. CEC-  cation exchange capacity measures the capacity of a soil  to hold and release nutrient ions.  Soils high in clay and organic
matter will have high CEC.  This measurement will vary across Maryland soils.  Adding organic matter is recommended where the CEC is less than 10.

Nitrogen

Plants need a relatively large amount of nitrogen for healthy growth.  Plant roots take up nitrogen in the
nitrate and ammonium forms.  Unlike most other nturients, nitrogen does not come from mineral soil.  Instead it comes “naturally” from organic matter, lightning and legumes (plants that convert nitrogen in air to nitrate nitrogen.)

Nitrogen and phosphorous are the two key nutrient pollutants of  waterways in Maryland that contribute to the complex problem  known as eutrophication. These nutrients encourage blooms of  algae that cloud the water and block sunlight causing underwater grasses to die. This has negative affects on aquatic life and  birds. Huge numbers of microorganisms in the water then use up oxygen as they feed on and break down the algae once it has died. Dissolved oxygen in the water quickly declines, depriving fsh, crabs and other aquatic life forms of needed oxygen.It is estimated that up to 80% of the nitrogen entering groundwater and surface water comes from non-point sourcesfarms, public lands, and private landscapes.  About one-half of excessive or mis-applied nitrogen fertilizer enters surface water fairly quickly as run-off from hard surfaces, lawns and gardens.  The other half travels for at least 10 years through soil and underground water before it eventually enters the Chesapeake  Bay (for Marylanders who live east of the Eastern Continental
Divide, located in Garrett County).

So mistakes in measuring and applying fertilizers today can contribute to nutrient pollution  problems many years in the future.Farmers, municipalities, corporations, AND homeowners all  have a duty to reduce the fow of nitrogen and phosphorous into streams, rivers, and the Chesapeake Bay.    Marylanders with lawns should be careful to drastically reduce or eliminate phosphorous fertilization if their soil test results show phosphorous (phosphate) levels that are “adequate”, “optimum”, or “excessive”.  The following companies  offer lawn fertilizers that contain no phosphorous or a low percentage (3%-5%) of phosphorous: Lebanon-Seaboard (Greenview), Espoma, LESCO, Scotts.