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Published on 11/26/03

The scoop on soil: how sweet it is

By Mike Isbell
University of Georgia

Some things you just know are sweet -- ice cream, apple pie, clean babies. Farmers and gardeners sometimes refer to their soil as sweet and even speak of sweetening it.

How sweet is the soil around your home? If you don't know, you need to find out. But don't go out and taste a spoonful -- have it tested.

"Sweet" soil is simply soil that's only slightly acid. The pH is probably the most important thing to know about your soil. It shows how acid your soil is. The lower the number, the more acid the soil.

So what?

It's important to know your soil's pH because plants have a certain pH level at which the nutrients in the soil are most available to them. If the pH of your soil is wrong, the plants could be starving for those nutrients, even if they're right there in the soil.

So what's the best pH? It all depends on the plants you're trying to grow. Take centipede grass, for example. The pH for good centipede growth is 5.5, but it will tolerate a pH below 5. Other grasses need a higher pH, somewhere around 6.

If you find you have a low pH, add lime. Fortunately, that may be the cheapest thing you soil needs.

Whatever plants you have, whether they're fruit trees, shrubs, vegetables, forages or turf, you can't know if you need to lime, or how much lime to add, if you don't know your soil's pH.

You need to test it

Take a soil sample that's representative of the area. To do that, get samples from 10 to 15 spots from 3 to 4 inches deep for lawns (8 to 12 inches for orchards). Mix the samples for each kind of plant. From the mixture, bring about a pint sample to your county office of the University of Georgia Extension Service. They'll have your test results in about a week.

Fall is a good time to add lime, because winter rains will help activate the lime in the soil. But the best time to add lime is whenever you need it.

That may be all the "sweetener" you need.

(Mike Isbell is the Heard County Extension Coordinator with the University of Georgia College of Agricultural and Environmental Sciences.)

Mike Isbell is the Heard County extension coordinator with the University of Georgia College of Agricultural and Environmental Sciences.