Sampling Soils for Fertilizer and Lime Recommendations
A good representative soil sample is the basis for a good soil test. Soil testing helps in determining soil nutrient levels and deficiencies in your soil and provides a basis for wise use of fertilizer and lime. Test results obtained from the regular soil test include: current pH, Phosphorus, Potassium, Calcium and Magnesium levels; plus fertilizer and lime recommendations, based upon what is to be grown.
- Plastic pail
- Garden trowel or spade, sampling probe or soil auger
- Plastic pint size sandwich bags
Taking the Sample
Soil samples may be taken at any time during the year when temperatures (lack of frost) and moisture conditions permit.
- Determine the area(s) you will be sampling. This may be a farm field (no larger than 10 acres per sample), garden plot, flower bed, lawn, etc.
- Using your trowel, probe or other sampling device, take 20 samples consisting of vertical columns or cores of soil approximately 1/2 - 1 inch square in cross section to the depth needed. Suggested sampling depths are as follows: Farm Field - 8 inches; Garden - 8 inches; Flower Bed - 5-6 inches; Lawn - 3 inches; Trees & Shrubs - 8 inches.
Avoid sampling unusual areas unless such locations are sampled and packaged in a separate soil box. Such areas may cause inaccurate test results that would not be representative of the whole area being sampled.
Sample in a random pattern throughout the area to be sampled. Place your 20 soil samples in the plastic pail.
Preparing & Packaging the Sample
When you have finished taking all 20 samples, mix the soil in the pail thoroughly with your hands.
If the soil is very wet at sampling time, it may be necessary to partially air dry the sample in order to obtain an adequately mixed sample. Do not use artificial heat, such as an oven, to dry the soil.
If the soil is very dry at sampling time, it may be necessary to crush the soil cores with a stick or piece of wood, and then mix.
After the sample is thoroughly mixed, fill a pint size plastic sandwich bag with soil in your pail. Remove stones, plant roots, leaves, worms, insects, or other non-soil matter from the soil in your bag. If you already have a soil sample box, seal the bag and place in the sample box. Follow the instructions below completion of the accompanying MSU SOIL TEST INFORMATION SHEET. If you do not have a sample box, seal the bag and bring your sample to the Conservation District Office. District staff will assist you in completing the information sheet.
On the sample box write your name, address, sample number (1, 2, A, B or whatever designation is meaningful to you), and county. It may be easier to write this information on the box BEFORE filling it with soil. It is not necessary to complete the remaining information below sample number, as this will be listed on the MSU SOIL TEST INFORMATION SHEET. Now, complete the MSU SOIL TEST INFORMATION SHEET appropriate for your sample(s). The sheet with green printing is for farm or field crops. The sheet with blue printing is for gardens, lawns, flowers, trees, etc. It also is labeled "For Special Crops or Urban Clients."
Green Sheet - Farm Fields
Complete the name, address, county and number of samples lines at the top of the form. If you have any comments that may help in the analysis of your samples, list them in the area at the top marked COMMENTS. Next, fill in the columns on the bottom of the sheet, following the example shown.
In the column marked GROWER SAMPLE IDENTIFICATION write the sample number(s) from your sample box(es).
In LAST CROP column list the code number of the last crop grown in that field, from the list on the back of the form.
In the next two sets of columns, CROP & YIELD GOAL, list the code number of the next two crops to grown, from the list on the back, and yields is bushels per acre or tons per acres.
In the ACRES REPRESENTED column list the acres of the field.
In the SAMPLING/PLOWING DEPTH column list how deep the soil was sampled, in inches.
If manure was applied to the field, write in the amount applied in tons/acre in the MANURE APPLIED column.
In TESTS REQUESTED column check the box with the "1" to indicate this is a standard soil test.
Blue Sheet - Garden, Lawn, Flowers, Etc.
Complete the name, address, county and number of samples lines at the top of the form following the GENERAL INSTRUCTIONS listed on the left side of the form. Next fill in the columns on the bottom of the sheet, following the example shown.
In column "A - GROWER SAMPLE INDENTIFICATION" list your sample identification number(s) from the sample box(es).
In column "B - CROP" list the code number of what is being grown from the list on the back of the form.
In column "C - SAMPLING/TILLAGE DEPTH" list how deep the soil was sampled, in inches.
In column "D - TESTS REQUESTED" check the box with the "1" to indicate this is a standard soil test.
Delivering Samples to Testing Lab
If you have a sample box and the information sheet described above, you can mail the sample(s) and completed information sheet(s) to the soil testing lab yourself, following the PROCEDURES FOR MAILING SAMPLES panel on the sample box. If you do not have a sample box, bring your soil sample(s) to the Washtenaw County Conservation District Office and we will help you.
Once soil samples have been analyzed a soil test report is prepared. The report will first be sent to the Washtenaw County MSU Extension Office, where an agricultural or horticultural agent will look it and add any comments to the report. The report will then be mailed to you. Sample results may take anywhere from 2-5 weeks, depending upon the time of year, and volume of samples to be analyzed by the lab.
If you have any questions about taking a soil sample, filling out the forms, etc. call the Conservation District at 734-761-6721 extension 5.