Repairing Flood Affected Soils with Gypsum
Whilst soils should not be worked until the excess water has drained away, in some cases waterlogging may continue, esp in sandy or clay soils where there is a pan or clay pan (shallow impermeable clay layer) just below the surface soil. Drainage could be improved to this area by adding gypsum to the area.
Waterlogging is also known to increase soil salinity. Salts in the subsoil can move up the profile into surface soils through rising water tables and flooding. The soil can become highly concentrated with salts resulting in damage to roots, especially as the soil dries out. When root function is impaired by a lack of oxygen, plants have difficulty keeping sodium and chloride out of the roots and they end up accumulating more salt than normal. The addition of gypsum (which contains calcium) to the soil can assist with displacing salt from the soil profile.
