Soil pH and Liming
Applications of lime
are often necessary to raise soil pH into a
good growing range for turfgrasses. While some plants, such as
Rhododendrons, prefer an acid soil and don't like liming, most
other garden plants in the northeastern US will respond well to an
increase in the soil pH. A soil test will tell you for sure.
Generally speaking, most lawns prefer a soil that is
nearly neutral, in the range of pH 6.5 to 7.2 (pH 7.0 is
neutral)
What is
soil pH?
Soil pH tells you how "acid" the soil
is. A lot of rainfall can make soil more acidic, since rain
contains hydrogen. Some lawn fertilizers can make the soil more adidic,
like the ones containing ammonium forms of nitrogen.
If soil pH is too low or high,
nutrients already in the soil become unavailable. Adjusting the
soil pH can have the same effect as fertilizing since it
"releases" nutrients that were already there.
The majority of plants grow best between pH 6.5 - 7.2, with 7 being neutral.
Soil tests are the best way to find out what your soil needs. Most
states have land-grant universities with agricultural extension services
who sell soil test kits.
Lime
Products
More finely ground
limestone will breakdown faster in the soil and raise the pH faster. The
fineness of the lime can be found on the lime bag label. Mesh sizes are
used to indicate particle sizes.
Pelletized forms of lime
Powdered lime is
reformulated into pellets to ease handling and application. Even though
this type of lime costs more, we recommend using it due to greater ease
of application.
Powdered forms of lime
Powdered lime is
cheaper than pelletized lime but is much more difficult is handle.
Powdered lime is very dusty and hard to apply with a lawn spreader,
since it wants to 'bridge' over the opening. If you must apply powdered
lime with a spreader, try only filling the hopper part way, thereby
reducing the likelihood of 'bridging.'
Pelletized lime products can be easily
spread with a cyclone spreader
Lime
varieties
While several varieties of lime
are available, try using agricultural forms such as calcium carbonate or
dolomite.
Dolomite
Dolomitic lime has more Magnesium than regular calcium carbonate. Soil
tests will usually indicate if you need to increase your magnesium
level.
Calcitic Lime
Most of the lime you find for sale at garden shops will be calcium
carbonate. It's usually the cheapest variety, especially if it's
powdered instead of pelletized (see the differences above).
Hydrated Lime
and Quick Lime
Don't use these types of lime on your lawn since there is a great
potential for burning your grass.
C.C.E.
Calcium Carbonate
Equivalent (CCE) gives you a way to compare the effectiveness of lime.
Soil test recommendations are based on this standard rating. Less
effective liming materials (with a CCE less than 100-percent) will
require slightly more product to get the desired results. You can use this formula
to calculate your particular lime application:
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How much lime to apply considering the CCE
Soil
test lime recommendation amount
divided by your lime's CCE
x 100
Example
Your soil test calls for
50 pounds of lime per 1,000 square feet of lawn area. You bought a lime
product with a CCE of 90
50 divided by 90 =
.55
.55 x 100 = 55 pounds per 1,000 sq ft
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Applying Lime
Due to the slow
movement of lime through the soil, it is best to mix lime with the soil
if at all possible. In the case of a new lawn or garden, attempt to
rototill lime into the soil. In the case of established lawns,
core
aerate the lawn first to create better entryways into the soil profile.
While it is not always possible or necessary, many recommendations
indicate that lime applications and fertilizer applications should be
made at least 2 weeks apart.
Fall is usually the recommended season for applying lime, due to the
upcoming freeze-thaw cycle during winter assisting with lime's
penetration into the soil.
Read
the label on the lime bag
and follow the guidelines.
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