2.3.2.5. Reaction of liming material with organic and
inorganic acids.
The liming materials directly react with organic acids formed
in soils to neutralize them.
Some reactions are as follows:
2RCOOH+CaCO3= (R.COO)
2Ca+H2O+CO2
HNO3+CaCO3=Ca
(NO3)2+H2O+CO2
H2SO4+CaCO3=CaSO4+H2O+CO2
RCOOH is produced by decomposition of organic matter in soils.
Nitric and Sulphuric acids are produced by mineralization of organic nitrogen
and sulphur compounds. They are produced from fertilizers also.
2.3.2.6 Rate of reaction of liming material
The time period needed for completion of reaction of the
liming materials is as follows:
Table : Rate of reaction of liming
materials
|
Liming
materials
|
Time required
|
|
CaO
|
Few weeks
|
|
Ca(OH)
|
Few weeks
|
|
CaCO3
|
One year
|
|
CaCO3MgCO3
|
More than one years
|
Source Rayar, 2000
2.3.2.7 Rate of application
The amount of lime required will vary with the degree of
acidity, the soil type and the kind of lime material. Light, sandy soils
require less lime than soils high in silt and clay. It is always a good
practice to have the soil tested to determine the amount and kind of lime
required. Soil test mailers and sampling instructions are available from County
Extension Offices.
Liming the lawn is an important part of good maintenance and
should be included in the schedule.
However, many enthusiastic gardeners are apt to over-lime.
Generally, applications of lime should only be made every three to five years.
Soil tests will aid the homeowner in determining the exact applications to be
made. Single applications of over 150 pounds of lime per 1,000 square feet
(three tons per acre) are not recommended. If over 150 pounds per 1,000 square
feet are needed, apply half one year and the remaining half two to three years
later, after rechecking the soil pH.
It should be remembered that too much lime can be as damaging
to lawn grasses as the lack of lime.
Also, lime is not a cure-all to all lawn maladies but an
ingredient which can correct soil acidity, thus creating favorable conditions
for other factors to occur which develop favorable conditions in soil for lawn
grasses.
It is important that homeowners know that lime is necessary
and how much is needed so that they can make the proper application for the
first step toward a healthy lawn (Clifford, 2003).
2.3.2.8. Time of Application
To obtain maximum efficiency and faster action, the best time
to apply lime to the lawn is when the soil is being prepared for planting. This
applies to the sub-soil as well as the topsoil because lime moves very slowly
through the soil. Research has shown that it takes up to two years for lime to
move two inches through the soil.
Applications of lime on established lawns may be made at any
time of the year, the most favorable time of the year being fall, winter, or
early spring, in that order. If applied when the soil is too wet, it is
difficult to obtain an even distribution.
If heavy equipment is needed to spread the lime, make the
application on level areas when the ground is frozen. Less damage is made to
the soil and grass under these conditions. Alternate freezing and thawing and
early spring showers hasten its penetration into the
soil (Clifford, .2003).
Lime must be spread evenly over the entire area because it
does not move horizontally. The use of a spreader insures a better distribution
and permits the lime to be placed next to flower beds or in close proximity to
acid-loving plants.
Pelleted lime is now available at most garden centers.
Pelleted lime costs a little more but has several advantages in that it goes
through a spreader more easily; may be spread by hand without being covered by
dust; dust does not drift or blow into areas where lime is not wanted;
eliminates such problems as tracking lime onto patios, etc. or into the house;
and is easier to clean up if the bag is broken.
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