Sodium is not a plant nutrient but it does play a role in soil health. High levels of sodium indicate salinity problems or sodicity problems such as poor soil structure. Excess sodium can also reduce the uptake of other
For healthy and productive soil, you should aim for a sodium concentration of less 1.0 meq/100g (meq = milliequivalents - this is a special term used to describe the amount of some elements in soil).
High sodium levels can be remediated by watering more frequently and applying gypsum. It is also worth investigating the source of soil sodium. The use of bore water and changes in the level of the water table can affect soil sodium levels. Installing a rainwater tank can be a useful step in preventing contamination of soils with sodium. If your property is on the coast, you will probably need to grow plants that tolerate moderate to high levels of salt.