Salinity analyses are commonly used to assess damage caused by salt water spills. Salinity analyses require preparation of a saturated paste by adding water to a sample of dried and ground material. Measurements are made on the filtrate from this paste. Salinity analyses report soluble ions, that is, ions in the filtrate. Consequently, results for most packages are reported in meq/L (milliequivalents/litre) as well as mg/kg.

Sodium Adsorption Ratio (SAR) = Na / [(Ca2 + Mg2) / 2] ½

Values for Ca, Mg, and Na must be in me/100g

Theoretical Gypsum Requirement (TGR) = 0.00335 x a2 {(1/b2) - (1/c2)} x % saturation t(ha-15 cm)-1

Results in tonnes per hectare to treat a 15cm depth

In a typical case TGR = 0.22 x a2 {(1/b2) - 1/c2)} t(ha-15 cm)-1

To convert to tons/acre - 6" divide by 2.2.

a= meq Na per L of saturated paste

b= target SAR

c= actual site SAR