As in all other soil amendments, it is better to apply gypsum during plant dormancy or in autumn or winter. Of course, under the right conditions and presence of sufficient water, gypsum can be applied to the soil in any season of the year. Gypsum has average solubility and relatively low salinity. Consequently, it does not cause soil salinity if applied during the growing season of plants. In general, taking its form (pulverized or granular) and degree of purity, intensity of soil sodicity and the soil depth to be amended into consideration, gypsum can be applied in the following ways:
- Dissolved in irrigation water
- Broadcasted on soil surface but not incorporated into soil
- Mixed with the soil on the ground surface (to a depth of 10 cm) by disking or with deeper soil (to the depth of 30 cm) by plowing
Some important points
- In most cases, and in soils with moderate sodicity levels, it is better to broadcast gypsum on soil on the ground surface and then mix it with surface soil (to the maximum depth of 10 cm) by disking or plowing This mixing improves gypsum application efficiency compared to broadcasting it on the ground surface.
- Mixing gypsum with soil at a lower depth, especially when gypsum is not applied at the calculated rate, yields better results compared to applying it at great soil depths. This is especially observed in lands under crop cultivation.