An accurate soil analysis is vital to understanding your soil. To achieve this, an accurate soil sample is needed. In this page, we hope to show you the proper ways to pull and pack the samples in preparation for shipment to our facility.
Samples originating outside of the U.S. require specific USDA clearance, and may also have to be priced differently according to the service you require – please contact us for the proper procedures, and information concerning cost of analysis and turn-around time before sending any soil or plant samples from outside the U.S.A.
Taking a Good Soil Sample
The way the soil samples are taken is extremely important, as the recommendations you receive from soil tests will only be as good as the samples you send for analysis. Following the instructions below will assure that the samples you send are taken in the way we need them for a proper analysis.
When to take a soil sample
Soil samples may be collected at any time of the year, provided that the area is not suffering from prolonged drought, that no nitrogen has been applied in the last 30 days and no sulfur has been used in the last six months.
Late spring and early summer sampling avoids the rush, shows the soil’s fertility at its best, and gives time to plan a soil fertility program that can begin directly following harvest if necessary. However, if no samples have been taken within the last two years, the best time to sample is as soon as circumstances permit.
Generally, sampling should be done every year if fertility is high and/or trace elements are being used to achieve top yields. CAUTION: without special arrangements, we recommend that if possible, no soil samples ever be sent for analysis when a soil is so extremely dry that plants will not grow there.
Prepare a map of the areas being tested
A good map makes your sampling repeatable from year to year and is useful at the time of fertilization. Designate a number, or some other identification, even a name – up to 8 characters – for each field. Use permanent lines such as roads, ditches, and fences for boundary lines.
Divide the field map into areas that have the same soil color, slope, texture, drainage, and past history of erosion. Each area should have the same cropping history, fertilizer and manure treatments, and the same intended crop for all the ground within that area. Assign each of the areas sampled a specific number or letter (or a combination of both) so you can correctly identify it.
For example, Field #2 could have three areas: A – the high ground, B – the sloping ground, and C – the low, level ground. The numbers written on the sample bag would be 2A, 2B, and 2C. See Figure 1 for the sample map.
It is recommended that sampled areas represent no more than 20 acres (8-9 hectares) the first year our testing program is used, even if soils are uniform in texture and relief. Areas with taller or shorter plants, different weed or grass patterns, higher or lower yields, etc., should be avoided or sampled separately if large enough to fertilize properly. The next time samples are taken, combine those areas that by analysis have been shown to be alike. You may wish to combine very small areas that have all the same characteristics, into one composite sample.
Sample at least 300 feet (92m) away from gravel or crushed limestone roads and stay at least 20 feet (6m) away from fence rows or the edge of a field.
Avoid, or sample separately the following:
- Eroded hillsides or low spots
- Terraces, ditch banks, roadbeds, or fence rows
- Animal droppings, urine spots, burn piles, manure, straw or haystacks
- Areas around sheds, barns, and/or where buildings have formerly stood
- Lime, fertilizer, chemical spill areas, and fertilizer bands
- Dead and back furrows
- Drought-stressed areas
- Areas where large amounts of sulfur have been applied in the last two to six months, or where nitrogen has been knifed in or recently broadcast in large amounts.
See also For Those Who Utilize Soil Tests.
Collecting the Samples
The Sample Bag
Use a new soil-sample container, new plastic bag, or new plastic container. Soil-sample bags are available free from Kinsey Agricultural Services. Zip-loc bags are fine – as long as they have never been used – but put Scotch tape over the writing or attach masking tape to write on because all types of marking ink can rub off the bag during shipment. Do not use paper sacks from the grocery store, bread wrappers, or such items, due to possible contamination. Avoid using a plastic bucket that has been used for other purposes. Even repeated washings of a bucket used to mix salt and minerals for feed can still result in contamination of the sample.
Label the sample bags with your name, the farm name (if any), field number and sample area. Prepare a map or sketch of the area for your own records. Make sure the labeling on the bag matches the number of the field and area on your map. Labeling the bags to match the areas before taking the sample helps.
Taking the Sample
A SOIL PROBE is recommended for easiest and best sampling results. Using a soil probe or shovel, sample down to a depth of 6 and a half – 7 inches (17cm), or to the depth the soil will be thoroughly mixed when worked if that will be deeper than 6 and a half – 7 inches.
For no-till crops, orchards, vineyards, pastures, hay meadows, lawns, etc., where soils will not be worked, the depth should be 4 inches (10cm). Sampling to the proper depth is extremely important if we are to provide each grower with the correct recommendations.
Put the soil, using several probes from like areas to make up the sample, into the sample bag. Removal of obvious debris (roots, leaves, etc.) is fine but unnecessary as it will not adversely affect the sample. If you do remove debris from the sample, be careful that none of the actual soil is removed with it.
Probe the soil every 50 to 100 paces, always taking a minimum of 5 probes per composite sample for smaller areas, and one probe for every 1 (one) to 2 (two) acres from larger areas. Only a small amount of soil is necessary for analysis. A cupful of soil is more than enough. Just be sure your sample represents the entire soil profile, if mixed, in order to send only a small portion. Please remember : this will be a very detailed analysis, which will only be as accurate as the sample you send.
Our “Hands-On Agronomy” DVD or Video Workshop has a section on taking soil samples properly, and provides a visual look at how to sample. Should you be interested please see our Publications page for ordering information.
Sending Soil Samples to Kinsey Agricultural Services
Pack the samples tightly. For larger packages (more than 2 or 3 samples), we recommend UPS (United Parcel Service), FedEx (Federal Express), or a reputable shipper of that type.
Presently, within the United States, the US Postal Service has a small pre-paid box which can be ordered from USPS.com, or the local Post Office, packed full and sent for a set flat-rate charge. Just be sure to pack the samples tightly to avoid spillage or breaking open inside the box.
Soils may be sent wet or dry (use a Zip-loc or plastic-lined bag for wet samples). Samples can be dried at home by spreading them on waxed paper and air-drying. DO NOT DRY THE SAMPLES IN AN OVEN. It is okay to leave samples to dry in the sun.
Please enclose a Soils Worksheet with your samples. Alternatively, you can request Soil Worksheets via our Contact Us page, or call us at (573) 683-3880. Be sure to complete the Worksheet as fully as possible. What you put on the Worksheet determines how the tests will be run and how our recommendations will be made. Completion of the Worksheet also helps us to keep turnaround time, and charges, to a minimum.
If your soil samples originate in the U.S.A. or Canada, please send the Soils Worksheet along with the samples and payment to us at our Missouri address.
If you are sending soil or plant samples from outside the U.S. please first contact us for the correct procedure. Failure to do this may result in your samples being destroyed by Customs or inordinate delays in processing! We will send you the relevant exemption stickers and address labels, to conform to USDA regulations. Please check with us that we can meet your deadline.