Soil testing is an important part of ensuring your garden grows well. Soils vary in their structure and ability to grow acceptable crops due to nutrient content, pH levels, climate, and biological activities in the soil from microorganisms and insects. Testing your soil ensures it is suitable for growing the specific crop you are planting.
Test results rely on you taking a good soil sample. When collecting soil samples, follow the instructions of the soil laboratory you are using or the instructions on your store-bought kit, says Ohio State University. Take the sample with a shovel or a specialized soil sampling tool that allows you to dig a core sample from the ground. Take several samples from throughout the yard to cover any variances in different areas of your garden or landscape.
Store-bought kits are sold at many garden centers or through websites. Kits bought over the counter are often cheap and are reusable. They provide only a general sampling of the soil pH and the fertility status of the soil, however, and do not give specifics on how to change the soil quality or what quantity of materials you may need to do so.
Most university extension services as well as some garden centers provide laboratory tests. Results of a laboratory test are more accurate than store-bought tests, providing a result within 1/10 of a pH unit. Experienced professionals conduct the soil tests. Tests are not overly expensive and are available in most areas. Some cities provide them free to residents. The test results give specifics on how to change your soil fertility for the better and you are often allowed a follow-up with technicians.
Soil tests ensure you accurately apply materials such as lime and fertilizer to your lawn. Excess fertilizer may cause runoff and phosphorous contamination of local waters if not applied correctly, says Rutgers New Jersey Agricultural Experiment Station. Applying materials appropriately means most of the material is used. Having a soil test also helps you manage your soil pH accurately. Low pH makes the soil acidic, while a high pH level makes the soil alkaline. Although many plants require a slightly acidic soil, soil that is too acidic or alkaline traps nutrients, keeping them from the plants.
When to Sample
Extension services recommend soil samples every year for soils heavily gardened and every three years for landscape plants. Samples are best taken a couple of months before the soil is planted to give any soil amendments recommended by the test time to take effect.