You have taken a soil sample and the soil testing laboratory has just sent you the results. Wonderful. But what does it mean? There is no reason to get your soil tested if you do nothing with the results. There is valuable information in there. Today’s article will help you understand how to read the testing report in order to make the right preparations for our garden:

The standard soil test from most laboratories measures soil pH (acidity), organic matter, phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sodium (Na). Certain plants will have different requirements for specific nutrients.

Soil pH

pH is the measure of acidity or alkalinity of a solution. It is formally a measure of the activity of dissolved hydrogen ions. A solution is considered to be neutral when the concentration of hydrogen ion is equal to the concentration of hydroxide ions. A neutral solution has a pH of 7. The pH scale ranges from 0 to 14. pH values less than the neutral 7 indicate acidity, while numbers greater than 7 indicate an alkalinity. In soil the pH directly affects nutrient availability. Plants thrive best in different soil pH ranges. Azaleas, rhododendrons, blueberries and conifers thrive best in acid soils (pH 5.0 to 5.5). Vegetables, grasses and most ornamentals do best in slightly acidic soils (pH 5.8 to 6.5). Soil pH values above or below these ranges may result in less vigorous growth or symptoms of nutrient deficiencies.

pH & Lime. Lime is commonly used to correct a soil’s acidity. The pH value is used in conjunction with exchangeable acidity (Ac) in determining lime rates. Once lime is applied pH can be used to check if correct measures were met.

Nitrate-Nitrogen (NO₃-N) and Sulfate-Sulfur (SO₄-S)

Nitrogen is normally the most limiting nutrient for optimum plant growth. Soil tests that estimate soil N availability are not currently used because soil N exists in many forms which may change with time and influence plant availability. Soil nitrogen (N) and sulfur (S) are measured in nitrate-nitrogen (NO₃-N) and sulfate-sulfur (SO₄-S) forms. For most crops grown in Arkansas, nitrogen fertilizer recommendations are developed from research trials and are based on previous crop, soil texture, yield goal and sometimes cultivar. Analysis for soil nitrate-N, however, is done routinely only for a few selected crops, and it is used to refine their N-fertilizer recommendations. Soil samples can be analyzed for nitrate-N if requested for other crops, but fertilizer-N recommendations, particularly for lawns and forages, are not adjusted.

Sulfate-sulfur and nitrate-nitrogen can leach in sandy soils and typically accumulate above the dense or clayey soil horizons. For this reason, positive crop responses to sulfur fertilization are not common in clayey soils. As organic matter decomposes, sulfur and nitrogen are released into the soil solution. As a consequence of these complex reactions, the concentrations of these nutrients may vary considerably with time, environmental conditions and soil depth. Recommendations for sulfur fertilization are based on cropping history and, to some extent, on soil test level, especially for corn, cotton, wheat and forages.

Phosphorus (P) and Potassium (K)

Phosphorus and potassium are two of the three macronutrients (the other being nitrogen) required by plants for optimum growth. They are required in larger amounts compared to the micronutrients.

Phosphorus. Fertilization is not likely when the soil tests:

Under 36ppm (72lb/acre) row and forage crops,

Above 25 ppm (50 lb/acre) for fruit crops

Above 75 ppm (150 lb/acre) for vegetable production

Potassium. Fertilization is not likely when the soil tests:

Above 175 ppm (350 lb/acre) for vegetables and row and forage crops

Above 90 ppm (180 lb/acre) for fruit crops

Calcium (Ca) and Magnesium (Mg)

Most sandy soils have calcium concentrations below 400 to 500 parts per million (800 to 1,000 lb/acre), while clayey soils usually test above 2,500 ppm. Normally, the higher the calcium level, the greater the soil clay content. Recent limestone applications may result in higher calcium levels. If the soil pH is maintained in the recommended range for the crop grown, calcium deficiency is very unlikely. In general, the higher the clay content, the more lime will be required to raise soil pH to the desired level.

Any good soil test laboratory will provided an explanation of each element tested for. Recommendations for correcting problem issues may also be made. Added soil amendments can be done during site preparations when till and cultivating. Before planting be sure to correct any imperfections in your soil quality, your plants will thank you by granting you a generous harvest.

Best Regards,

Jimi Demetriou

References:

North Carolina. Department of Agriculture & Consumer Services. Agronomic Services Division.

http://www.ncagr.com/agronomi/

University of Arkansas. Division of Agriculture.

http://www.uaex.edu/

If you have decided to get your soil tested professionally, I have compiled a short list of facilities by state that will test your soil. While we know there are many professional companies that also provide the service, I have tried to limit the list to state run facilities.

Alabama

Soil Testing Laboratory
118 Funchess Hall
Auburn University, AL 36849-541
(334) 844-3958

http://www.aces.edu/anr/soillab/

Get a soil collection kit from your local extension office and mail your samples directly to the lab. Results are mailed to you. Test for nitrogen and organic matter upon request for an additional fee.

Alaska

Soil Test Laboratories in Alaska

University of Alaska Fairbanks
Agricultural and Forestry Experiment Station Lab
Palmer Research Center
533 E. Fireweed Ave.
Palmer, AK 99645
(907) 746-9482

http://www.uaf.edu/coop-ext/publications/freepubs/FGV-00044.pdf

Call the state extension office at (907) 474-7246 to locate your local office, from whom you can get a list of labs that includes the one we’ve listed. Select and contact a lab, and the staff will instruct you further. Most of these labs don’t give recommendations, your local extension agents will provide those for you.

Arizona

United Horticultural Supply
4429 N. Highway Dr.
Tucson, AZ 85705
(800) 825-2474
This is a commercial lab. Call them for instructions and a collection kit.

Arkansas

University of Arkansas

Division of Agriculture

http://www.uark.edu/depts/soiltest/

California

Soil and Plant Lab
352 Mathew Street
Santa Clara, CA 95050-0153
408-727-0330
408-727-5125 Fax
splab7@earthlink.net
www.soilandplantlaboratory.com

Compost analysis: particle size, available nutrients, organic content, estimated C/N ratio, bulk density, pH, salinity, sodium, moisture content, bioassay growth trials with radish and rye grass. Four locations in California, Washington, and Oregon.

Colorado

Soil, Water & Plant Testing Lab
Natural & Environmental Sciences Bldg., Rm. A319
Colorado State University
Fort Collins, CO 80523-1120
(970) 491-5061

http://www.extsoilcrop.colostate.edu/SoilLab/soillab.html

Call the state extension office at (970) 491-6281 to locate your local office. Get a collection kit from your local agent and follow the instructions. Or, if you prefer, you can just call the university lab directly.

Connecticut

Soil Nutrient Analysis Laboratory
6 Sherman Place, Unit-5102
Storrs, CT 06269-5102
(860) 486-4274
You can purchase a soil collection kit directly from the lab or from your local extension office. You can also request a brochure with instructions for sampling and submitting your soil sample.

Delaware

Soil Testing Program
Dept. of Plant & Soil Science
University of Delaware
Newark, DE 19717-1303
(302) 831-1392

http://ag.udel.edu/other_websites/DSTP/

Soil test kits can be purchased for $7.50 from your local extension office. The office listed above can assist you if you can’t find the extension office in your phone book.

Florida

Soil Testing Lab, IFAS
631 Wallace Building
University of Florida
Gainesville, FL 32611-0740
(352) 392-1950
This office will refer you to your local extension office for a soil collection kit, which you can then submit to IFAS or a private lab of your choice.

Georgia

Soil, Plant & Water Analysis Lab
University of Georgia
2400 College Station Rd.
Athens, GA 30602
(706) 542-5350

http://aesl.ces.uga.edu/

The lab will refer you to your extension office which will supply you with instructions, a collection bag and price list. You return the sample to you local office and they submit it to the lab. Your results are returned to your extension office where an agent will review them and provide you with recommendations.

Waters Agricultural Laboratories, Inc.
257 Newton Highway
P.O. Box 382
Camille, GA 31730-0382
229-336-7216
http://www.watersag.com/pesticide.htm

Hawaii

Agricultural Diagnostic Service Center
Sherman Lab 134
University of Hawaii
1910 E. West Rd.
Honolulu, HI 96822
(808) 956-6706
Call the Agricultural Diagnostic Service Center (ADSC), at the University of Hawaii in Honolulu at (808)956-6706. Mail the sample to the lab or to the nearest extension office and they will mail the results to you. You can call ADSC or the home gardening section at (808)453-6050 for advice after you get your results.

Idaho

Analytical Science Lab
Holm Research Center
University of Idaho
Moscow, ID 83844-2203
(208) 885-7081
Contact your local extension office for a soil collection kit; the lab listed here can help you find your local office. The results from your soil sample will be sent to that extension office where an agent will review the results and make recommendations.

Illinois

Universal Analytical Laboratory Inc.
15006 State Route 127
Carlyle, IL 62231
(618) 594-2627
http://www.ualab.com

Indiana

A&L Great Lakes Labs
3505 Conestoga Dr.
Fort Wayne, IN 46808-4413
(219) 483-4759
http://www.algreatlakes.com
You can call A&L for information and a collection kit, or you can just send 1 cup of soil plus a check for $15 and specify that you want the homeowner package “S10″ test. Indicate the type of recommendations desired (e.g., lawn, garden, shrubs, etc.) Results and recommendations will be mailed to you. This lab accepts samples from Indiana, Michigan, Ohio, Illinois and Wisconsin.

Iowa

Iowa State University Soil Testing Lab
G501 Agronomy
Ames, IA 50011
(515) 294-3076
Call the state extension office at (515) 294-4576 to locate your local office, where you’ll get specific instructions. Mail your sample directly to the lab.

Kansas

Kentucky

University of Kentucky Soil Testing Labs
103 Regulatory Service Building
University of Kentucky
Lexington, KY 40548-0275
(606) 257-7355
This lab will direct you to your local extension office, which will give you a soil collection kit. You return your soil sample to that same local office, which will send it to the lab for you and contact you with the results.

Louisiana

Soil Testing Lab
125 Madison B. Sturgis Hall
Louisiana State University
Baton Rouge, LA 70803
(225) 388-1261
Contact the lab or your local extension office for a soil collection kit. Both you and your extension office will receive a copy of the results.

Maine

Soil Testing Lab
125 Madison B. Sturgis Hall
Louisiana State University
Baton Rouge, LA 70803
(225) 388-1261
Contact the lab or your local extension office for a soil collection kit. Both you and your extension office will receive a copy of the results.

Maryland

Massachusetts

Soil Testing Lab
West Experiment Station
University of Massachusetts
Amherst, MA 01003-8021
(413) 545-2311
http://www.umass.edu/plsoils/soiltest/
A variety of tests beyond the basic soil assessment are offered, including Soluble Salts, Total Soil Metals and Soil Texture. This lab also tests compost.

Michigan

Soil & Plant Nutrient Lab
Michigan State University
Plant & Soil Sciences Building, Rm. A-81
East Lansing, MI 48824-1325
(517) 355-0218
Although you can send your soil sample directly to the lab, your best bet is to contact your local extension office to obtain a soil collection kit and fee schedule. (The lab will direct you to your local extension office if necessary.) Your soil test results will be sent to your extension office.

Minnesota

Soil Testing Lab
University of Minnesota
135 Crops Research Building
1902 Dudley Ave.
St. Paul, MN 55108
(612) 625-3101
Contact your local county extension office for a soil collection kit and information. You or your extension office can submit the soil sample to the lab, which will return the results and recommendations to the person who submitted the sample.

Mississippi

Soil Testing Lab
Mississippi State University
Box 9610
Mississippi State, MS 39762
(662) 325-3313
Call the state extension office at (662) 325-3036 to locate your local office or call the lab directly for soil testing instructions. Send your sample directly to the lab.

Missouri

EarthCo
P.O. Box 50084
St. Louis, MO 63105

http://www.earthtest.com
Gives organic recommendations for soil amendment.

Soil Testing Lab
23 Mumford Hall
University of Missouri
Columbia, MO 65211
(314) 882-0623
Contact your local extension agent or the lab listed above for soil collection materials. You can mail samples directly to the lab or to your local extension agent, but all results and recommendations will be sent to the agent, who makes recommendations and forwards the bundle to you.

Montana

Land Resources & Environmental Sciences
Montana State University
Marie Rippy, Administ. Asst.
Bozeman, MT 59717
(406) 994-3515
MSU does not provide general soil testing to the home gardener. Contact the above at MSU for a list of private soil testing labs. If you have a specific soil problem or question pertaining to your test results, your local extension office may be able to have the problem reviewed by this lab.

Nebraska

Midwest Laboratories Inc.
13611 B. St.
Omaha, NE 68144

http://www.midwestlabs.com
A private lab that provides organic recommendations.

Soil & Plant Analytical Lab
University of Nebraska
139 Keim Hall
Lincoln, NE 68583-1571
(402) 472-1571
This office will refer you to your local ex

Ward Laboratories, Inc.
P.O. Box 788
Kearney, NE 68848
(308) 234-2418
http://www.wardlab.com

Nevada

Western Area Hort. Specialist
P.O. Box 11130
Reno, NV 89520
(702) 784-4848
Extension service master gardener volunteers in Nevada conduct free tests, but for pH and salinity only. For more extensive soil testing, request a list of private soil labs. Note: Nevada county extension agents are now called “extension educators.”

New Hampshire

Soil Testing Lab
University of New Hampshire
Spaulding Life Sciences
38 College Rd.
Durham, NH 03824
(603) 862-3210
Contact this lab or your local extension office for a collection kit and information on taking soil samples.

New Jersey

Rutgers Cooperative Extension Soil Testing Lab
P.O. Box 902
Milltown, NJ 08850
(732) 932-9295
This lab will answer questions about soil collection, costs, etc., and will direct you to your local extension office. If you are sending your soil sample in a kit purchased from your extension office you have already paid for your basic test.

New Mexico

Soil, Water & Air Testing Lab
Box 30,003, Dept. 3Q
Las Cruces, NM 88003
(505) 646-4422
Contact this lab directly or your local extension office for instructions on soil sampling procedure. Test results will be sent both to you and your local extension office. Extension office will then notify you if anything needs to be adjusted.

New York

Cornell Nutrient Analysis Lab
804 Bradfield Hall, S.C.A.S.
Cornell University
Ithaca, NY 14853
Soil sampling kits may be obtained from your local extension office, some commercial firms, or by contacting this lab at Cornell. Discuss any questions regarding your results or recommendations with your local extension office.

North Carolina

N.C. Dept. of Agriculture

Soil Testing Section

4300 Reedy Creek Rd.

Raleigh, NC 27607

(919) 733-2655

You are encourage to contact your local extension office to obtain a soil collection kit. However, this office will provide you with a kit if you have trouble finding that local office. (Some commercial fertilizer suppliers also have kits available.) Test results and recommendations will be sent to you.

North Dakota

Soil Testing Lab
Waldron Hall
North Dakota State University
P.O. Box 5575
Fargo, ND 58105
(701) 231-8942
This lab will supply instructions for soil testing or refer you to your local extension office for instructions and a soil collection bag, depending on your location. A soluble salts test is recommended for some regions. If you request organic correction of any problems, mention the organic amendments that are easily available to you, such as compost, manure, etc. Results and recommendations will be sent directly to you.

Ohio

Brookside Laboratories, Inc.
308 South Main St.
New Knoxville, OH 45871
419-753-2448
http://www.blinc.com/

Spectrum Analytic Inc.
P.O. Box 639
1087 Jamison Rd.
Washington Court House, OH 43160
740-335-1562
http://www.spectrumanalytic.com/

Oklahoma

Oklahoma State University
Soil, Water & Forage Lab
048 Agricultural Hall
Stillwater, OK 74078
(405) 744-6630
http://clay.agr.okstate.edu/extension/swfal/intro.htm
This lab will refer you to your local extension office for soil testing information and a collection bag. The extension office will submit your sample to the lab. (Note: there is a soil collection kit available at some garden centers which can be sent to the lab with $12 for a basic test.)

Oregon

Soil and Plant Laboratory, Inc.
2235 SE 60th Ave
Portland, OR 97215
503-557-4959
http://www.soilandplantlaboratory.com
Plant pathology testing/diagnosis, Soil/artificial mediachemistry, fertility, physical properties, particle size distribution, organic matter content, carbon/nitrogen ratio, bulk density and more.

Pennsylvania

Agri Analysis, Inc.
P.O. Box 483
280 Newport Rd.
Leola, PA 17540
717-656-9326
http://www.agrianalysis.com/

Agricultural Analytical Services
Penn State University
Tower Rd.
University Park, PA 16802
(814) 863-0841
http://www.aasl.psu.edu
You can purchase a soil sample collection kit at your local Penn State Cooperative Extension County Office—you’ll find the list of county offices on the lab’s Website or you can call the lab for your county’s office. You then mail your sample directly to the lab. The results will be sent to you with a copy to your local extension agent.

Rhode Island

Soil Test Coordinator
Cooperative Extension Ed. Center
University of Rhode Island
Kingston, RI 02881
(800) 448-1011
In Rhode Island only, contact the cooperative extension’s master gardener hotline at the above number to receive instructions and a fee schedule. You will then send your soil sample to the soil testing lab at the University of Massachusetts, which will send results and recommendations to you.

South Carolina

Agricultural Service Lab at Clemson University
Clemson, SC 29634-0313
(864) 656-2068
You must contact your local extension office where you will receive a collection kit and instructions. You pay the fee at the extension office and then the soil sample is sent to the lab. The office listed here will direct you to your local extension office if you have trouble finding them.

South Dakota

Soil Testing Lab
South Dakota State University
Box 2207 A, Agricultural Hall 07
Brookings, SD 57007-1096
(605) 688-4766
This lab will refer you to your local extension office or send you a soil testing kit directly. Your extension office will then send your soil sample to the lab.

Tennessee

University of Tennessee Soil Testing Lab
5201 Marchant Drive
Nashville, TN 37211-5112
(615) 832-5850
Call the state extension office at (423) 974-7114 to locate your local office, which will supply you with sampling materials (some fertilizer dealers and co-ops can also do this). Mail your samples directly to the lab. The results will be sent to your local extension agent, who forwards them to you.

Texas

A&L Agricultural Laboratories
302 34th Street
P.O. Box 1590
Lubbock, TX 79408
(806) 763-4278
http://www.al-labs-plains.com
You’ll get organic soil recommendations from this lab. Email address - scot@al-labs-plains.com.

Texas Ag Extension Service
Soil, Water & Forage Lab
Rm. 345, Soil and Crop Sciences
College Station, TX 77843-2474
(409) 845-4816
This office will answer questions about fees and services, or will refer you to your local extension office for instructions and a soil collection bag.

Utah

Soil Testing Lab
166 Ag Science Building
Utah State University
Logan, UT 84322-4830
(435) 797-2217
This lab will help you directly or will refer you to your local extension office for instructions and collection materials. The staff will also refer you to a specialist if your test reveals a specific problem that requires such help. They encourage you to test your soil for salinity due to the small amount of rainfall in this region.

Vermont

Ag & Environmental Testing Lab
219 Hills Building
University of Vermont
Burlington, VT 05405
(802) 656-3030
Contact your local extension office or the lab listed here for test information. The results of your soil test will be sent to you and to your local extension office, where master gardeners will help interpret recommendations.

Virginia

A & L Eastern Agricultural Laboratories
7621 Whitepine Road
Richmond, VA 23237
804-743-9401
http://www.al-labs-eastern.com/

Virginia Tech Soil Testing Lab
145 Smyth Hall (0465)
Blacksburg, VA 24061
(540) 231-6893
http://www.ext.vt.edu
This lab will refer you to your local extension office for information on how to obtain a collection box, forms and instructions. Results are mailed to you and your local extension office; any questions regarding recommendations should be addressed to that local extension office.

Washington

West Virginia

West Virginia University
Division of Plant & Soil Sciences
G140B Agricultural Sciences Building
P.O. Box 6108
Morgantown, WV 26506-6108

Call the state extension office at (304) 293-5691 to locate your local extension office, which will supply you with sampling materials. Mail your samples directly to the lab.

Wisconsin

Midwestern Bio-Ag
Highway ID, Box 126
Blue Mounds, WI 53517
(608) 437-4994
Fax: 608-437-4441 A private lab that provides organic recommendations.

UW Soil & Plant Analysis Lab
University of Wisconsin - Madison
5711 Mineral Point Rd.
Madison, WI 53705
(608) 262-4364
http://uwlab.soils.wisc.edu
Contact the lab directly or go through your local extension agent. Either way, this lab is very helpful. They’ll even lend you a soil probe.

Wyoming

Soil Testing Lab
Dept. of Renewable Resources
University of Wyoming
P.O. Box 3354, Univ. Station
Laramie, WY 82071
(307) 766-2135
Contact this lab or your local extension office to obtain soil testing instructions and collection bags.

Even though this list should serve as a good starting point, I understand that it is most likely incomplete. If you have come across any soil testing labs on your own we would love to have you share them with us. Also remember that your soil report is only as good as the sample you take for them. Continue reading How to Take a Soil Sample

If you have decided to get your soil tested at a Soil Testing Laboratory, you are going to want to give the facility a good sample of your soil. The better the sample the more accurate the lab’s report will be. An accurate lab report will give you a better understanding of your soil and provide you with proper information when you make nutrient and pH adjustments when doing site preparations.

When Should I Test My Soil?

A soil test can be taken any time throughout the year. We recommended in our article 3 Steps to Prepare your New Garden Site to test your soil prior to planting in order to give enough time for corrections to be made. Two months prior is more than enough, taking a sample to early may lead to inaccuracy due to shifting levels of nutrients and pH over time. I also recommend soil testing your vegetable garden at least once a year in order to keep a close eye on your garden.

Where Should I Sample?

Each soil sample should represent only one soil type or soil condition. If your soil is different in composition in multiple locations, use a different sample for each. Different soil samples should also be taken based on how they were up kept. A selection that was a previous part of a weekly moved lawn should be sampled differently than an overgrown section. To get a report on a general area within each soil type you can take composite sample. A composite sample will give you a more representative reading on the area by taking the multiple samples. Taking 10 or more samples in a zigzag like pattern will give you the best results. The more samples you take, the more representative your sample will be of your garden.

How to Take a Sample

Now that know when and where we should take a sample from it is time to start getting into how to take a good quality sample.

Dig the appropriate length. When sampling for a vegetable garden we will want to take samples from as deep as we plan on tilling or cultivating. This is usually between 6 – 8 inches in depth. To take a sample us a clean soil probe, spade, hand garden trowel, or shovel to collect samples. Brass, bronze and other galvanized tools should not be used when taking a soil sample, due to copper or zinc contamination.

Remove any physical contaminates. Physical objects such as grass or rocks should be removed.

Mix sample cores well. When mixing together sure to use a clean, preferably plastic, bucket and that fertilizer and other chemicals have been washed out. Also make sure not to mix together samples from different unique locations.