Gypsum

Recycled Gypsum is Calcium Sulphate (CaSO4. 2H2O) which contains 19% calcium and 22% Sulphur.

Gypsum has been used on soils across East Anglia where poor soil structure has become present through the flooding of marshes or on clays with poor soil structure. It has shown to be very useful in vegetable production to supply Calcium to potatoes or to improve tuber quality for carrots and potatoes.

Gypsum has been used to improve soil structure. The calcium in the gypsum increases the ability of the soil particles to flocculate. This is the formation of small crumbs in the soil structure which is needed for good rooting, drainage and nutrient uptake.

For land which has a high magnesium content the application of Gypsum has transformed the soil properties to enable a dramatic reduction in the required horse power to work the soils more easily.

Why is it needed?

Where land is flooded by salt water, the Sodium in the salt replaces calcium ions on the soil cation exchange sites. The sodium ion, which has a single positive charge is much less effective than the calcium ion which has a double positive charge at holding the particles together. As a result, water is attracted to the clay particles by osmosis and this causes the soil particles to swell and disperse. Creating a collapse of the soil structure leading to poor drainage.

 

How does it work?

When the gypsum is applied to the poorly structured land, the calcium in the gypsum displaces the sodium which is holding on to the soil particles. The displaced sodium then chemically combines with the sulphate in the gypsum to form a sodium sulphate solution which is then lost through drainage water. Soil structure is then restored as water is no longer attracted to the soil particles due to the calcium holding onto the soil, which flocculates (turns into small crumb size soils).

 

How much to Apply?

Gypsum should be applied between 3-6 t/ac (7- 13 t/ha) depending on structure of the soil. To ensure the exact amounts are applied standard soil analysis should be carried out along with Exchangeable Sodium Chloride and Conductivity.

Spreading is carried out by a belt driven spreader’s such as a Breadle and low ground pressure machines are available for this such as a Terrigator.

 

All Gypsum sold by Needham Chalks Ltd is produced under the PAS 109 protocol so that we can guaranteed the best quality product is delivered and spread on your land.

 

For More details on Gypsum or to speak to an advisor please contact the office here or a field advisor directly here.

Gypsum for Vegetables

Gypsum has also been found to be very useful on Vegetable crops. To find more information about this please see our Gypsum on Vegetables page here.

 

Other qualities of Gypsum are:

  • Improves soil structure
  • Reclaims saline soils
  • Prevents soil Crusting / Aids seed emergence
    • Applied to the surface before heavy rain or irrigation to prevent crusting of the soil and aid seed emergence.
  • Improves compacted soils
  • Cultivations to wet or moist soils more accessible
    • Soils treated with gypsum have a wider range of soil moisture levels where it is safe to work before there is danger of compaction or de-flocculation.
  • Stops water run off and Erosion
    • Improves water infiltration rates into soils and enables the water carrying capacity to remain high to prevent erosion when rapid rainfall occurs.
  • Prevents water logging of soil
    • Gypusm prevents the water logging of soil by enabling the soil to maintain a good structure which doesn’t contain to much sodium resulting in the swelling of clay and excess water.
  • Enables organic matter to bind to clay.
    • Organic matter when applied with gypsum is able to bind on the the clay more available due to the calcium.
  • Helps plants absorb nutrients
    • Calcium is essential to the mechanisms by which most plant nutrients are absorbed by roots, High levels of Calcium are supplied in gypsum.
  • Good source of sulphur to soils