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Quality soil promotes healthy plants

One of the most important components of growing plants is the soil where they are growing. The soil provides the necessary water and nutrients required for the plant’s metabolic functions.

Soil testing is an accurate way to assess the nutrient status and the (pH), which is a measurement of the acidity of the soil. Applying fertilizer without a soil test can result in the application of too much or too little lime and fertilizer required for optimum growth. Consider having your soil tested through Gwinnett County Extension.

The pH is an important component of the soil. It has a scale of 0 to 14. 7 is neutral, and below 7 is acidic and above alkaline. The pH level determines the availability of the various nutrients to the plant. If it is too high or too low, then the nutrients will become insoluble so that the plant is unable to absorb them from the soil. In soils that are more acidic, iron and zinc are more soluble and can be toxic to plants. Some plants, such as blueberries and azaleas, require more iron and thus they need acidic soil.

The most important step in soil testing is the collection of a representative sample to submit for soil testing. Using a small shovel, take at least ten random samples from the area and thoroughly mix them together in a container. Samples should be one inch in diameter, four inches deep for turfgrasses and six inches for other plant materials. Place two cups of the mixed soil into a plastic bag. The soil must be completely dry before bringing to the Extension office. This sample should not include any plant roots. Take separate samples and submit them for each area with different types of plants since they have differing pH and fertility needs. For example, if you have a property with  fescue in one area and ornamental trees and shrubs in another area, take two separate soil test samples: one for the fescue lawn and the other for the ornamental trees and shrubs.

Submit the soil samples at the Gwinnett County Extension office at 750 South Perry St. #400, Lawrenceville, GA 30046. Our office hours are Monday through Friday, 8:00 am to 5:00 pm. The cost is $8.00 per sample. You should receive the results within 10 to 14 days by mail or e-mail. A soil test will give the pH, phosphorus, potassium, calcium, magnesium, zinc, and lime levels. Nitrogen is not routinely a part of the normal soil-testing regimen since the test has limited predictive value. Nitrogen is quite mobile in the soil and may leach out before planting. Recommendations given are based on the amount of nitrogen required for the plant growth in a year. The lime and fertilizer recommendations are given in pounds per 1,000 square feet. Test results will advise you on what types of fertilizer that should be applied, how much you need, and when to apply it. If you have any questions regarding the tests, contact the Extension office.

Before applying lime or fertilizer to your lawn and garden, you should have the soil tested to assess its pH and nutrient levels. By doing so, you can take the correct steps in managing the fertility of the soil to ensure healthy plant growth. It can also save you money and reduce the likelihood of excess fertilizer being washed away into bodies of water and polluting them.

Timothy Daly, is an Agricultural and Natural Resource Extension Agent with Gwinnett County. He can be contacted at 678-377-4010 or