Gypsum is a naturally occurring soft crystalline mineral commonly found in arid inland area in regional Victoria. It is quite easy to mine and process, which is reflected in the price ex the quarries.
Gypsum contains sulphur in the sulphate form which is the form taken up by the plant roots, so if a quick response to sulphur is required then Gypsum can be used.
Gypsum is commonly used as a soil conditioner is it contains significant levels of calcium however due to its pH being 8.5, it has little if any effect on the soil pH and cannot be used as a substitute for lime. It is used as a soil conditioner when the soil pH doesn’t require changing and the soil is still quite low in calcium and high in magnesium.
Gypsum is typically categorised in 3 grades, Grade 1 is the highest grade and the only type of gypsum we recommend. It typically contains a minimum of 15% S and 19% Ca however it can contain higher levels.
Gypsum is very effective in alkaline soils that have high concentrations of Sodium and/or Magnesium. When a soil has high levels of sodium and magnesium present, clay particles bind together resulting in a very tight and compacted soil profile. This reduces water infiltration, possible seedling emergence and pasture production. By applying Gypsum to the soil, the release of calcium ions allows the displacement of sodium and magnesium to occur, which results in a better balanced soil.