Gypsum (calcium sulphate) when applied to soil dissolves in rain and or irrigation water and interacts with the fine clay particles.
This interaction improves
soil structure making the clay more stable when wet and
reducing the tendency of soil surfaces to set hard when
Sloppy mud from the untreated area (above) contrasts with
well-structured friable soil after a gypsum application.
THESE ARE THE BENEFITS
- Water will seldom pond on treated areas because of much improved water infiltration.
- Makes soil more friable making cultivation easier, and cost effective. With the improved germination, run-off is minimal, reduces erosion.
- Gypsum will maintain soil structure by inhibiting dispersion. It is the calcium in gypsum which replaces sodium in the soil, consequently crusting is reduced.
- Supplies a cheap and effective source of sulphur without affecting soil pH.
- Cooke Plains Gypsum passes through a 2mm screen and has a very low sodium content.
Material Safety Data Sheet
GEOLOGY OF COOKE PLAINS GYPSUM
The deposit borders the Eastern reaches
of Lake Alexandrina, a former tidal lake at the mouth
of the River Murray. Swamps extending eastwards
from the present lake beyond Cooke Plains were flooded
during the last period of high sea level, and subsequent
evaporation deposited Crystalline Gypsum which was then
blown by prevailing winds into a series of Dune Ridges
150-500m wide and up to 12 metres high over a length of
3 kms along the North Eastern extremity. The dunes
are made up of white flower Gypsum (Gypsite) covering
seed Gypsum (Gypsarenite), which is the main type distributed.
There are substantial shallow layers below swamp level
and the water table. Workable area was estimated by the
Mines Department to be in excess of 3 Million Tonnes.