By Carolyn Bahm
At $3 per test, the Mississippi Cooperative Extension Service’s soil testing program is a dirt-cheap way to enhance your plants’ survival rate.
Detailed knowledge about what’s in the soil helps gardeners make timely adjustments, usually by adding fertilizer and/or lime. Hundreds of samples are tested annually in Lee County alone, according to county agent Jackie L. Courson.
He said many gardeners test their soil in the fall because, if lime is needed, it takes time to work before the spring planting.
“But if you haven’t tested your soil, anytime is a good time to test,” Courson emphasized.
Soil should be tested anywhere that green plants grow: Lawns, flower beds around houses, vegetable gardens and even that herb garden in the back corner of the yard.
Courson explained the benefit of testing. “When you go to the doctor and tell him you have an ailment, you would want to know where you are what the problem is before you treat the symptoms.”
Mississippi State University does the actual chemical analysis of the soil for $3, compared to $18 charged per sample at many private labs.
Looking at lime and pH levels
Because Tupelo is built on a large lime outcropping, many area gardeners assume their soil is naturally rich with lime. Don’t bet on that, Courson said.
“The biggest problem I see with people and their soil is they’re fertilizing fine but not not paying much attention to their lime.”
Lime releases the nutrients in the soil, making them available to plants. Without the proper amount of this critical element, plants may not be able to use the nutrients that are present in abundance all around them. (It’s comparable to a starving person having a can of food but no can opener.)
Azaleas and blueberries are among the few plants that thrive in an acid soil; in contrast, most others tend to grow best in a “sweet” soil, or dirt that is less acid. Most flourish in the 6.0 to 7.0 pH range.
The pH level also can go too high: With soil above 7.5 pH, gardeners will begin to see nutrients tied up in the soil, resulting in chlorosis (yellowing) of foliage.
Too-high pH is most common around brick homes: Lime-based mortar falls around the house during construction, and gardeners are surprised to find their azaleas grow poorly in flower beds around the house.
How to take a soil sample
Results are only as good as the sample you take:
– First decide which different areas of your lawn and garden need to be sampled. Take separate soil specimens for each area that is distinctly different in appearance, crop growth or past treatment. (Hint: Don’t take a sample right after fertilization, because results will be misleading.)
– For each area: Use a shovel to dig up small soil samples from about 2 to 4 inches deep; do this in 15 to 20 different locations throughout that one area. Mix the dirt thoroughly; reserve one pint and discard the rest. This process better ensures that the composite sample will be an average representation of the entire area.
– Take each one-pint sample to your county agent’s office. You’ll get assistance in filling out the accompanying form and sending each sample to the correct address. The form will identify what will be planted in that area. The cost for submitting the soil sample is $3.
Results will be available in seven to 10 days from the time the sample arrives at the MSU lab unless the soil is too wet, Courson said. Final reports are mailed to the gardener and also to the county agent for filing.
Courson advises testing most home horticultural crops annually and testing most agricultural crops every two to three years.
Testing often is important because soil can change. For example, adding potting soil can change the soil’s makeup, and adding fertilizer will lower the pH. Crops also take up nutrients at different rates.
Adding up the benefits
Only testing will give gardeners the detailed information they need for soil management. The process also helps professionals: Area country clubs are regular soil samplers, Courson said. “They live and die by their greens and their turf and their fairways.”
Ricky Self, golf course superintendent for the Tupelo Country Club, said he annually tests every tee, fairway, green, flower bed and ornamental planting at the facility. He uses the results from the MSU labs for the course’s environmentally responsible management plan.
“It’s very beneficial,” he said about soil testing. “It can solve problems, but I think the biggest thing it does is give you a game plan for your fertilization. … We know what we’re putting down and when to do it.”