Good reasons to test soil; Plus, get a free soil pH test at Hartford Flower Show

By Dawn Pettinelli - UConn Home & Garden Education Center
Featured Article - posted Wed., Feb. 5, 2014
- Contributed Photo

If you haven’t gotten around to doing it yet, late winter to early spring is actually a great time of year to have your soil tested. True, one does have to wait for the soil to defrost, which varies from year to year. Soil testing is important to the home gardener because you cannot look at the soil, feel or smell it and tell how much phosphorus, potassium or other essential elements are available for plant growth. Different plants have varying soil pH and nutrient requirements. A soil test determines what nutrients are in your soil at the present time and will indicate deficiencies or excessive levels, either of which can contribute to unsatisfactory plant growth and development.

The pH level of your soil will affect the availability of plant nutrients. Soil pH is a measure of the acidity of the soil, with 7 being neutral. A soil pH below 7 is acidic and above 7 is alkaline. Native Connecticut soils usually have a pH ranging from 4.0 to 5.5. Most of our garden plants, however, are not native, so the soil pH often has to be adjusted. Many nutrients, especially phosphorus, become less available to plants at lower pH levels. Some elements, like aluminum, become more soluble under acidic conditions and may adversely affect plant growth.

Also, some crops are more sensitive to pH levels than others. For instance, vegetables such as asparagus, lettuce and peas do not perform as well if the soil pH level drops below 6.0.

Although fertilizers are often referred to as plant food, remember plants make their own food (proteins and carbohydrates) through the process of photosynthesis. To do this, the plant needs air, water, sunlight and certain nutrients found in or added to the soil. Some of these nutrients include nitrogen, phosphorus, potassium, calcium, magnesium and sulfur. Nutrients that are needed only in tiny quantities like boron, manganese and molybdenum are called trace elements or micronutrients.

Taking a soil sample involves several easy steps. To determine the number of samples for testing, take into account whether the soil looks different in various parts of the yard and whether it was limed or fertilized at different rates. For instance, a vegetable garden that had lots of amendments added to it would be tested separately from a lawn area with few amendments. Areas of noticeably poorer growth might also be tested separately.

For each area to be sampled, collect a representative sample. Do this by taking small samples from the top to about 6 inches down in several spots throughout the sample area. Place each of these sub-samples in a clean container and mix them up. Then remove one cup of this mixture for testing. This would be more representative than if soil was only collected from one hole.

Samples can be sent by mail or hand-delivered to the UConn Soil Nutrient Analysis Laboratory on the Mansfield Depot Campus in Storrs. Call the lab if you would like a soil testing brochure sent to you, or visit the website Local Cooperative Extension offices also have soil testing information. There is a nominal fee for soil analysis. April through early May are the lab’s busiest times, but if your sample is received in late February through mid-March, the turnover time should be a week or less.

After testing the soil, recommendations for limestone and fertilizer recommendations are mailed. The results you receive will indicate the pH and amounts of nutrients present in the soil and what, if anything, needs to be added for optimum plant growth. 

For a free soil pH test, visit the UConn Home & Garden Education Center booth at the Hartford Flower and Garden Show, Feb. 20-23, at the Hartford Convention Center. Bring a half cup of soil and they will test your soil pH and make limestone recommendations while you wait.

Before you invest in your plants, invest in your soil. Your rewards will be abundant. If you have questions on soil testing or on other indoor or outdoor gardening topics, call the UConn Home & Garden Education Center, toll-free, at 877-486-6271, visit the website, or contact your local Cooperative Extension Center.

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