Following on from last issue Paul Plant investigates the role of soil additives that enhance the organic garden.
Gypsum is a natural mineral fertiliser which is composed of Calcium (Ca) and Sulphur (S). Gypsum is frequently used to supply calcium to soils but tends not to affect the pH, although reports have indicated it can cause some soils to become
more acidic with extended use over time.
Lime is a natural mineral fertiliser available in a number of forms. Two commonly available forms are ground limestone (calcium carbonate) and builder’s lime (hydrated lime, calcium hydroxide). Gardeners should only use ground limestone.
Dolomite is a natural mineral fertiliser composed of Calcium (Ca) and Magnesium (Mg). It is regarded as a natural limestone
source with significant magnesium content of at least 8%.
Zeolite is a group of natural crystalised minerals that,
when dehydrated, develop a porous structure.
Diatomite is made up of the fossilised shells of diatoms, single-celled (unicellular) organisms. These natural layer formations of rock are called diatomaceous earth. High in silica, the typical chemical composition of diatomaceous earth is 86% silica, 5% sodium, 3% magnesium and 2% iron.