Maddy: Why is it important to soil test?

Published 5:26 pm Friday, November 17, 2017

Did you know that if the pH of the soil is less than 5.5, most of the fertilizer that is applied cannot be used by plant roots? Frequently I get asked the question of what is the first step to improving my lawn or garden. My response is always “When is the last time you soil tested?”  Without a soil test, adding lime and fertilizer is like flying blind.

Doing a soil test is like getting an x-ray to pinpoint exactly where the broken bone is located. Soil testing is an essential tool in diagnosing plant problems and improving plant production.

What does a soil test tell you? Soil tests measures the pH level. The pH level is a scale from 0 to 14 with seven being neutral. Below seven, soils are labeled acidic and above seven, soils are called alkaline. Most plants prefer a slightly acidic soil, 6.0 to 6.5. Azaleas and blueberries prefer soils with a pH of less than 5.5. Olive trees prefer alkaline soils.

If soils are too acid, nutrients such as nitrogen, phosphorus, potassium and magnesium become unavailable. At low pH nutrients such as iron, boron, manganese, copper and zinc become toxic to plants. Nitrogen becomes unavailable at a high ph.

Soil tests will also indicate nutrient levels for phosphorus, potassium, calcium, magnesium and zinc. This may depend on what plants you are growing. Fertilizer recommendations are also included. You may ask for three different crop recommendations for each sample submitted.

Normally, once medium to high fertility rates are achieved you should sample every two to three years. Vegetable gardens should be sampled every one to two years. Results are usually back in seven to 10 days.

The next step is to take a representative sample. Map out the location, the front yard, back pasture or garden area. Using a trowel or small shovel, slice to a four inch depth for lawn or a six inch depth for a garden.

Randomly, in a zig-zag pattern, walk the area and take samples. Place the sample in a clean bucket that has no chemicals in it. Stay away from unusual areas, sidewalks or ditches.

Mix thoroughly and fill to the line on the sample bag or fill a quart zip lock bag. If you have a sample bag make sure you fill the information requested. You can stop by the office to pick up sample bags or just bring in a zip-lock to save a trip.

If you use your email, we can get to the recommendation to you earlier. For lawns, specify the type of grass, for example Zoysia. Drop it off at the extension office. The cost is $9 per sample.

If you have questions after you receive the recommendations, I will be more than happy to help you out. Soil sampling is one of the best diagnostic tools we have.

What’s going on in Extension?

Nov. 20: Troup County Association of Beekeepers 7 p.m. at the Ag Center.

Nov. 21: Troup County Cattleman’s Association: “NRCS and FSA Programs.” Meal starts at 7 p.m. Cost $6, call ahead for reservations, (706) 443-7697. The program will start at 7:30 p.m. at the Ag Center

If you have any questions or concerns, stop by or call the office. UGA has a wealth of information for home and property owners.

Brian Maddy is the ANR Agent for Troup County Extension. The Troup County Extension office is located at 144 Sam Walker Drive, LaGrange. 30240 (706) 883-1675. Monday – Friday 8 a.m. to noon and from 1 to 5 p.m.