Gypsum is a naturally occurring mineral that complies with all current organic production regulations. Winstone's
horticultural gypsum is currently certified for use by organic growers under the BioGroŽ label.
Gypsum can safely be applied in almost all situations and even excessive applications are unlikely to
be damaging. Because of its neutral pH (around 7) it can be used when large amounts of calcium are required
without increasing soil pH.
A well nourished plant with a healthy root environment and a good root system is more resistant to pests
and diseases. Composts are very important for organic growers as they build up and maintain soil structure
and fertility. In addition to its beneficial effects on soil structure, gypsum improves the speed, efficiency
and mineral balance of composts. This facilitates the quick return of nutrients and organic matter to the soil.
Levels of the heavy metals are very low in
gypsum.
The build up of heavy metal residues (especially cadmium) is already a problem in some regions in New Zealand. In
addition to its general undesirability, heavy-metal build up can also limit root growth, reducing both nutrient and
water uptake by plants. Gypsum is a valuable and very safe natural material that is especially useful for organic
growers who wish to supply additional calcium and sulphur to their crops.
See Gypsum Material Safety Data Sheet (PDF 158Kb).
