Soil tests are used to determine the amount of essential nutrients in the soil needed for plant growth. The soil test results will be used to make a soil test report indicating the level of nutrients in your soil, the pH value or how acidic or basic your soil is, and will make a recommendation for the amount and type of fertilizer and/or lime you may need to add to the soil for optimum plant growth.
Following the recommendations for fertilization will help prevent problems associated with under- or over-fertilizer applications. Under-fertilization will cause nutrient deficiencies and over-fertilization can cause problems such as excessive vegetative growth, delayed maturity, salt burn, and wasted money. In addition, it can protect against environmental pollution resulting from excessive fertilizer applications. Testing the soil you are going to be planting in is very important because the soil may already contain high levels of phosphorus or calcium, and may already be in the correct pH range or higher. In these cases, adding additional lime or fertilizer containing phosphorus may create nutrient imbalances that reduce plant health.
Soil analysis needs to have 8 to 10 core samples throughout the area where you will be planting. The core samples will be combined together to create one composite sample. The composite sample should include soil from the surface to a depth of 6 inches in all areas, except for lawns where core samples should be taken from a depth of 2 to 4 inches. You can use a garden trowel to collect the core samples. Place the core samples in a clean plastic bucket and mix them thoroughly. The sample must not be excessively wet before it goes to the lab. Areas that have been fertilized or limed differently, such as lawns, shrub beds, and vegetable gardens should be kept separate and should be submitted as separate composite samples. This is because different type plants require different nutrient requirements. If you have a problem area where plants or turfgrass do not seem to grow well, take a separate soil composite sample from that location.
Bring a minimum of 2 cups of soil per composite sample in a clean jar or bag to your local Extension office. Be sure to keep track of which part your yard, landscape, or garden the sample represents. We will fill out the necessary paper work at the Extension for all the necessary analyses desired.
The Clemson University Extension Service recommends soil sampling every year. Soil samples can be taken at any time of the year, but it is best to sample the soil a couple months before planting a garden, establishing perennials, or before the optimum time for fertilizing lawns to allow plenty of time for the lime to react with the soil.
Stick around for the next article of the Garden Spot, Understanding your Soil Test Report.
For more information on soil testing please visit the HGIC website at hgic.clemson.edu. Tune in on Tuesday nights to watch “Making it Grow” at 7 p.m. on SCETV or mig.org. Email Outen at callenb@clemson.edu.
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