Soil sampling is a very useful tool if you are a homeowner or grow any ofthe following plants: turfgrass, ornamentals, fruits, vegetables, trees or houseplants. Soil sampling and testing is probably the most effective tool ahomeowner has to help determine soil nutrient levels. Soil tests can help savethe homeowner time and money as well as encourage a healthy environmentby reducing unnecessary fertilizer use.

Plants require sixteen essential nutrients to grow. Nitrogen, phosphorous andpotassium are major elements, and are required in relatively large amounts,whereas others like calcium, sulfur and magnesium are minor elements andare required in moderate amounts. Still others are required in extremely smallamounts, still just as important as the major nutrients. If any of the 16essential elements are not present in adequate amounts, plant growth anddevelopment will decrease. On the other hand, if some of the same nutrientsare present at excessive levels, they can be toxic to plants and be a source ofpollution in the environment.

It is very important to take soil samples correctly in order to receive accuraterecommendations. Homeowners are then able to apply the recommendedamounts of lime and fertilizer for maximum plant production. Soil samplesshould be taken dry as excess moisture increases the drying time of the soilsample and makes soil boxes unreadable. Late summer or early fall is a goodtime to sample soil so that adequate lime may be applied and can react withthe soil by raising the pH prior to spring planting. Sampling may be done atany time of the year, although it normally takes longer in the fall (6 -8weeks) for results to return than in the spring (2 -3 weeks). By sampling inthe fall, sufficient time is allowed to make plans for the spring fertilizerapplications.

The North Carolina Department of Agriculture (NCDA) Agronomic Division,in Raleigh, analyzes soil samples which are collected in North Carolina forFREE. The soil test results indicate the amount of lime and fertilizerformulation recommendations needed for the area sampled.

Soil pH is a measurement of soil acidity. If soil pH is less than 5.5 or greaterthan 7.5, (for most plant material), some essential elements may not beavailable to the plant while some toxic elements, such as aluminum, becomeavailable to the plant. Soil pH can be adjusted by applying granular or groundlimestone, to raise the pH or by adding sulphur to lower the pH.

To get a representative sample, the following steps need to be taken:

1)Collect 3 - 6 small samples, from within the top six inches (4 inchesfor lawns) of the soil, within the area of concern. It is important totake as uniform samples as possible (Example: 2 inch diameter, 6inches deep). The more small samples that are collected will give abetter, more uniform representation of the area. A bulb digger or shoveltake very good samples.

2)As samples are collected, mix them together thoroughly in a plasticbucket, as a galvanized or tin bucket can contaminate the soil andcause inaccurate test results.

3)Discard all stones, roots and debris. Transfer about a cup of soil fromthe small sample plastic bucket to the soil sample boxes provided bythe NCDA. Sample boxes and forms are free from the ExtensionService.

4)Give each sample box a number or code that will indicate the areasampled, along with your name and address on each box.

5)Fill out the information sheet and bring it, along with your samples, to the local Cooperative Extension Service office.

Visit the NCCES Soil Science publication on soil sampling by clicking here!

About the author:

Kenny Bailey is an Agriculture Extension Agent, Commercial Horticulture, serving Cumberland and Harnett Counties.

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Date created 2/5/97
Last revised on 2/26/02