Taking a Soil Sample


Routine soil testing helps landowners determine lime requirements, organic matter, and the amounts of available nutrients. The reliability of a soil test is only as good as the sample you submit. Follow these procedures to ensure your soil sample is representative of your property.

Where to sample

Obtain a soil survey map of your area through the NRCS Web Soil Survey. You can also draw a sketch of the property and the individual fields for a reference.

On the map or sketch, divide your property into fields or soil types. These sections should be as uniform as possible in terms of soil type and cropping and fertilizing history. If you have a problem on part of your property, you can determine if soil fertility is the cause by taking one sample to represent the “good” and the other to represent the “poor” area.

Taking a sample

Collect the soil samples by walking in a zig-zag pattern over the selected area. After the cores are dry, mix them thoroughly in a clean pail to make one composite sample for each site. Number these site samples and record the numbers on the map or sketch. The greater the number of collected cores mixed together, the better the sample will represent the average condition of the sampled area. Take a minimum of 10 samples for small areas and at least 15–20 samples for larger areas.

Sampling depth should be 4 to 6 inches deep for lawns, turf, or other perennial sod. For annually tilled crops, sample at tillage depth (usually 6–10 inches). Collect samples with either a soil probe, auger, garden trowel, shovel, or spade.

Soil Probe or Auger

A soil probe or auger is the best tool for sampling. An auger is necessary for very stony or gravelly soil. Push the probe (or push and turn the auger) into the soil to the desired depth, lift up to remove the core, and place it in a clean pail.

Garden Trowel, Shovel, or Spade

If a soil probe or auger is not available, collect your sample by pushing the blade of a garden trowel, shovel, or spade into the soil to the desired depth. Cut out a triangular wedge of soil and set it aside (replace after sampling). Slide your blade into the soil again removing a ½-inch-thick slice from one side of the hole. With a knife, trim the slice to about a 1-inch strip of soil down the center of the spade face. Place this “core” in a clean pail.

Submitting a sample

Before taking a sample, check with the lab the sample is being sent for a set of instructions. The MU Extension office offers soil sample analysis. A small fee will be charged for each sample. Be prepared to provide information on the field’s soil type and history of cropping, liming, and fertilizing. Keep the soil test results with your wildlife or landowner plan for future reference.

These recommendations are for crop production and considerably less fertilizer can be used on food plots. Lime is important for legume establishment and growth.

Recommended Soil pH Range for Crop Establishment

Crop Ozark Soils All Other Missouri Soils
Alfalfa 6.6 - 7.0 6.1 - 6.5
Clover 6.1 - 6.5 5.6 - 6.0
Cool-season grass 5.6 - 6.0 5.6 - 6.0
Lespedeza 6.1 - 6.5 5.6 - 6.0
Overseeding legumes 6.1 - 6.5 5.6 - 6.0
Warm-season grass 5.6 - 6.0 5.6 - 6.0
Sudan grass and Sudan/sorghum crosses 5.6 - 6.0 5.6 - 6.0
All row crops 6.1 - 6.5 6.1 - 6.5