To convert sodium concentration from saturated paste results from mg/L to mg/kg:
Saturation% = (Water in Paste (g) / Dry Sample (g) ) x 100% = (Water in Paste (mL) / Dry sample (g)) x 100%
Soluble Na (mg/L) x Saturation% = (Soluble Na ( mg / 1000 mL)) x (( Water in Paste (mL) / (Dry Sample 0.001 kg)) = Soluble Na (mg/kg)