Jarrod Miller, Extension Agronomist.
If you have had issues with tidal inundation of soils in the past or had some flooding this spring, you may be thinking about remediation methods to get the salt content down. While gypsum is a great method of ameliorating these fields, it works best if your salt issues come from sodium (Na). The calcium (Ca) in gypsum can replace Na on your CEC, which will let rainfall or irrigation leach it below the root zone. Fields where Na contents is greater than 15% of the CEC are the most likely to show toxicity issues and should be taken care of first.
However, if your total salt content is high due to Ca, Mg and Na, gypsum will not solve this issue. In these fields irrigation is your best option with recommendations of up to 6 inches of water to reduce salinity by 50% and up to 24 inches to reduce it by 90%.
