Friday, September 27, 2013

How to add Gypsum to soil


Gypsum (calcium sulphate) is added to soils that are heavy in clay which can be really sticky. Adding lots of organic matter such as compost with the gypsum helps to break down the clay to be easier on the plant roots to grow and not become water-logged.

Gypsum also releases minerals within the soil structure which where bound up in the clay particles so that they become available for plant nutrition.

Make sure that you use natural garden Gypsum, not the white builders' variety.


Ratio for Gypsum: 0.5-1kg to 1m2 of soil (dig through)


How do I know if I have clay soil?

Poor drainage is the first sign. There might be signs of moss, but not in every case. Grass may not grow in that area or plants that have been previously planted there never seem to thrive.

When the soil it moist, grab a handful and squeeze it together. If it stays firm, in shape and not crumbly it will be clay soil. Good loamy soil will soon fall apart and not stay in shape.

Do a 2 foot test hole first. Fill with a full bucket of water and time how long it takes to drain.
If water is takes 12-24 hours to drain you can be sure its a clay soil.

A second test is to use a glass of water. Drop in a 6mm size piece of dry soil. Let it stand for 24 hours without moving or stirring it. If it slowly falls apart in the water this soil should respond to gypsum being added. If it does not dissolve it might not be worthwhile to add the gypsum as the soil will not respond.

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