The Importance of Taking Good Soil Samples

A soil test is the only practical way of telling whether lime or fertilizers are needed. However, if the soil sample does not represent the general soil condition of the field or area from which the sample was taken, the recommendation and decisions may be wrong or misleading. An acre of soil to the depth of the root zone weights approximately 1,000 tons. Ten grams or less of soil is used for each test in the laboratory. Therefore, it is very important that the soil sample be characteristic of the field or area from which it was taken. The following guidance will help to take proper soil samples.

Sampling Area

Areas selected for sampling should be as uniform as possible. Do not mix soils of differing color and/or texture. As a general rule of thumb, anywhere that the soil differs because of significant factor; soil type, drainage, elevation, topography, productivity, management practice, tillage, etc. should be sampled separately.

Sample Depth

In general, soil samples should be taken to the root zone depth of 3 to 4 inches for yard and 6 to 8 inches for garden and food plots.

The area should be divided according to vegetation and soil characteristics. Red dots indicate sampling points. Use a zigzag approach when taking samples.

Materials Needed

Materials needed include: plastic pail, soil probe or shovel, and the bag provided in the AgroLab kit. Plastic material is recommended. Metals, such as galvanized, will compromise the soil analysis.

Sampling Procedures

1. Clear the ground surface of grass thatch or mulch. Using a trowel or shovel, push the tool to the desired depth into the soil.

2. Push a probe into your soil to collect the soil. If you do not have a probe, use a trowel or sharp spade. Push the tool down into the ground until you reach the desired depth. Pull the soil probe back out of the soil, and check to make sure it contains the soil. If using another tool, scoop the soil onto the tool and bring it back to you.

3. Repeat step 2 until you collect at least five samples from random spots.

4. Release the soil samples into a bucket. Confirm that the bucket is not made out of bronze, brass or aluminum because these materials potentially could contaminate your samples with traces of micronutrients. Use a plastic bucket instead.

5. Break up chunks in the soil and remove rocks and stones present. Mix the soil samples in a clean, labeled sample bag.

Tips & Warnings

  • When using a probe or other tools, make sure the tools are plastic, chrome-plated or stainless steel and not galvanized, which can contaminate your soil samples.
  • Check the tools to ensure they are free of fertilizer, lime or old soil, which can make your soil sample test results inaccurate as well.

Frequently Asked Questions

Q: When and how often should soil be tested?

A: Take soil samples at any convenient time. However, to receive an analysis and the recommendations early enough to enable getting the lime and fertilizer needed, it is best to sample in the Fall or early Spring. It is generally recommended staying consistent. If original samples were taken in the Fall, try to take new samples in the Fall also. Seasonal variation of some nutrients may occur. Soil should be sampled every 1 to 3 years. Fertility level and soil type can alter this schedule.

Q: How soon will I get my results back (turn-around-time)?

A: In general, results are received within 24-48 hrs of receiving the samples in the lab.

Q: How do I submit my samples?

A: You can contact our office via phone or email and ask for a homeowner's kit. We will mail one out to you. The kit will include a soil sample bag, soil sample submission test form and instructions, and a brochure with sampling instructions.

Q: How much does the kit cost and how do I pay?

A: The kit is $20.00 per sample. This includes a graphic report with appropriate nutrient and lime recommendations. You will also receive, along with your test results, our fact sheets to help with interpreting the report. You can include a check with your sample or you can provide your credit card information on the bottom of the soil sample submission form.