Your favorite garden spot just isn’t producing as it used to, in
spite of more fertilizer, careful
watering and better varieties. Is your memory fading, or were
those tomatoes really redder in
gardens past?

It’s not your memory.

It’s your soil’s nutrient balance, said Darbie Granberry, a
horticulturist with the University of
Georgia Extension Service.

“You may have neglected a very important task,” Granberry
said. “You have to soil test to
determine soil pH and fertilizer needs.”

Old-timers sometimes say soil sours and needs a “sweetening”
with lime.

That’s not far from truth, Granberry said. As heavy rates of
nitrogen fertilizer are applied over
time, the soil becomes more acid.

Most vegetables grow best at a pH of 6.0 to 6.5, which is only
slightly acid. If it dips below 6.0,
the gardener should be adding lime in the fall so it can be
worked in several months before spring
planting.

“The main purpose of applying lime is to correct the pH,”
Granberry said. “But it also supplies
needed calcium and magnesium, if you use dolomitic lime. Garden
vegetables need both of these
nutrients.”

The only accurate way to know your garden’s pH level is by soil
testing.

Your county Extension agent has soil test bags and information
on how to take a representative
soil sample. The Extension agent will submit your soil to the
UGA Soil, Plant and Water
Analysis Lab and help you interpret the test results.

Maintaining a proper pH is so important, Granberry said, because
many nutrients get tied up and
unavailable when the pH is too low. Without nutrients, plants
can’t grow properly.

“Adding extra fertilizer in a low-pH situation doesn’t
compensate for the low pH because many
of the added elements quickly become tied up, too,” he said.

Although soil testing is the only accurate way to learn the pH
level, you can let your vegetables
tell you when there’s a problem. Plants remain small or stunted
and usually show poor leaf color.
Leaves’ edges may also turn brown.

“Actual symptoms can vary considerably, depending on which
nutrient or nutrients are deficient
or toxic,” Granberry said. “Vegetable yields are reduced
progressively as the soil becomes more
acid. Little or no yields are obtained with a pH around 4.5 to
5.0.”

Take advantage of the fall season and your county agent’s
services, Granberry said.