About Soil Conditioning
Why is soil acidity important for plant nutrition?
Different types of plants require varying degrees of soil acidity.
Some plants are very sensitive to soil pH. The acidity or alkalinity
of the soil is measured by pH. Basically, the pH of soil is a measure
of the amount of lime (calcium) contained in soil or may be characteristic
of the amount of nutrients. Generally, soils in moist climates tend
to be acidic and those in dry climates tend to be alkaline, or basic.
A soil with a pH lower than 7.0 is acidic in nature and one with a pH
higher than 7.0 is alkaline. The soil must be adjusted to suit the plant
if it is not already within that plants requirement range.
Testing your soil pH
You can buy an inexpensive pH test kit at most nurseries or
hardware stores. These test kits generally consist of a test tube, some
testing solution and a color chart. To use a test kit, a sample of your
soil is placed in the tube, a few drops of test solution is added, then
it is shaken and left for an hour to allow the soil to settle. The solution
in the tube changes color according to the pH of your soil. The color
of the sample is compared with a color chart that is included with the
kit. Matching colors will tell you the pH of your sample. A pH probe
can also be used to test the soil solution, instead of a test solution.
What would you need to design a pH test kit of your own?
Adjusting your soil pH
Once you have determined the pH you can adjust the pH of the soil to
accommodate the plants in your garden using materials commonly available
at your local garden center.
Raising the soil pH to make it more alkaline
It is generally easier to make soils more alkaline than it is to make
them more acidic. Since different soil types react in different ways
to the application of lime you will have to add more lime to clay soils
and peaty soils than you would for sandy soils to achieve the same result.
To increase your pH by 1 unit and make your soil more alkaline:
* Add 4 ounces of hydrated lime per square yard in sandy soils
* Add 8 ounces of hydrated lime per square yard in loamy soils
* Add 12 ounces of hydrated lime per square yard in clay soils
* Add 25 ounces of hydrated lime per square yard in peaty soils
Correction of an overly acid soil should be considered a long term
project, rather than trying to accomplish it in one year. It is better
to test your soil each year and make your adjustments gradually. The
addition of hardwood ash, bone meal, crushed marble, or crushed oyster
shells will also help to raise the soil pH.
Lowering the soil pH to make it more acidic
If your soil needs to be more acidic, sulfur may be used to lower the
pH if it is available. To reduce the soil pH by 1 unit, mix in 1.2 oz
of ground rock sulphur per square yard if the soil is sandy, or 3.6
oz per square yard for all other soils. The sulphur should be thoroughly
mixed into the soil before planting. Sawdust, composted leaves, wood
chips, cottonseed meal, leaf mold and especially peat moss, will also
lower the soil pH.
CAUTION!!
* Always read and follow the manufactures recommendations when
using chemical products.
* Use appropriate protection such as a dust mask and gloves.
* The best way to adjust pH is gradually, over several seasons.
* Lime should be applied only when tests show it to be necessary.
* If the soil is excessively alkaline, you may find that you are better
off to build a raised bed using topsoil purchased from a nursery.
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Experimental Design
