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DALY: Soil testing essential in improving the quality of your soil

Timothy Daly

Timothy Daly

Even though the weather has been very cold lately, spring is around the corner and homeowners will be planting their landscapes with an assortment of plants. One of the most important components of having healthy garden plants is good soil.

The most accurate and effective way to assess the nutrient status and the relative acidity of the soil (pH) is through soil testing. Applying fertilizer without a soil test can result in the application of too much or too little lime and fertilizer required for optimum growth. The Gwinnett County Extension Service has provided a soil testing service for many years. Homeowners often use soil testing services to guide them in making decisions for wisely managing their home landscapes.

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 an 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 material. 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 both 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 a.m. to 5 p.m. The cost is $8 per sample. You should receive the results within 10 to 12 days by mail or email. The soil tests results include pH, phosphorus, potassium, calcium, magnesium, zinc, and lime levels. It will indicate what types of fertilizers are needed.

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. A call to the Extension office to speak with an agent will provide guidance if you have any questions.

The pH is one of the most important factors in determining a soil’s relative fertility. Different plants require different pH levels. For example, most plants need a pH 6.0 to 6.5; however, some plants, such as blueberries and azaleas prefer a lower pH of 4.5 to 6.0.

The soil test report shows available soil nutrients and pH, and recommendations for improving pH and nutrient levels. Fertilizer and lime recommendations are given in pounds (lbs) per square feet. Apply fertilizer according to soil test recommendations. Excessive fertilizer is wasteful and can lead to water pollution since it can be washed away when it rains.

Soil test results provide information on the nutrient status of your soil. This will help determine the amount and type of fertilizer as well as material to change the pH required to have healthy and attractive garden plants.

Winter is also a good time to decide on what to plant in your landscape. The Gwinnett County Extension Plant Sale has some excellent plants that are available for sale. Go to the Extension website at http://www.ugaextension.com/gwinnett to download the order form or call the Extension office for a form to be mailed to you.

Timothy Daly is an Agricultural and Natural Resource Extension agent with Gwinnett County Extension. He can be contacted at 678-377-4010 or tdaly@uga.edu.