Sodium (Na) should measure between 0.5 and 3% on the base saturation. It is rarely deficient (there being 6 ppm in rain), and should not (but sometimes does), exceed potassium in base saturation as sodium will be taken up by the plant instead. On hot days, this can lead to cell walls bursting and the plant dehydrating. In severe cases, the plants, including pasture, can die.
According to Perry Agricultural Soil Laboratories (PAL) results, we have yet to see a situation that warrants sodium being added to fertiliser. However, we have observed the negative effects of excess sodium, when applied to fodder beet.
If sodium is in excess, correct the calcium first, then use sulphur to reduce sodium if it is still in excess.
Sodium is involved in osmotic (water movement) and ionic balance in plants. Na may be important in some plants such as sugar beet, but is less so in fodder beet.