Soil testing is a method of determining the quality of your land for planting various types of plots. Whether you want a nice lawn, a healthy garden, or a beautiful landscape you need the proper amounts of nutrients in the ground. A soil sample tests for naturally occurring elements and additives such as phosphorus, calcium, sulfur, potassium, copper, magnesium, manganese, sodium and zinc. You can get a soil sample from your state university extension office.
You can do a soil test at any time, but it will be more useful if you plan it at the proper time. If you are going to plant in a certain area, the soil test should be taken soon enough so you have time to make the suggested adjustments. For established areas or lawns, take a sample in the late summer so you have plenty of time to make soil adjustments in the fall before the dormant period. Do not take a sample within six to eight weeks of applying lime, fertilizers or other chemicals to the ground. You will not get an accurate reading until the chemicals have a chance to work into the soil.
Never put your soil samples in dirty bags, jars or other holding media. Use new plastic sandwich bags or jars that have been cleaned with soap and water and rinsed well. Sampling equipment must be clean as well. Never use any buckets, spades or trowels that have been used to work in fresh fertilizer without washing thoroughly or it could give you a false reading. Don't use any equipment made of bronze, brass or galvanized steel because they can contain zinc and/or copper that could show up in your samples.
Keep different areas of soil samples separate from one another. A garden needs different criteria than a lawn or established woodland. Even your back and front yard should be considered separate zones. Collect samples from each type of plot you have on your property or want to work on. If your main interest is in planting a new garden area in a portion of the backyard, do not take soil samples from the front yard. Take the soil samples from the location the garden is going to be.
Don't just take one sample of an area. Take at least six samples, and try to get most of them from any trouble spots you are aware of. For instance, if you want to improve your front yard and there are several areas that have yellow or bare spots, pick as many sub-samples from those locations as possible. Use a large, clean container to dump all of the samples from each area in, and mix them up well to form one large sample of the location. Take the final soil sample from that location mix.
Different areas require different sample depths to get an accurate reading. No matter where you are testing, take soil samples below the vegetation line. That means remove all sod, thatch and mulch from a lawn, or plant and mulch from a garden. Sweep away any loose debris such as leaves or twigs before taking a sample. According to the North Carolina Department of Agriculture, samples for a vegetable or flower garden or established shrub and landscaped area should be at a depth of 4 to 6 inches. For lawn locations the sample should be taken at 4 inches deep.