Does high sodium mean saline? Understanding "salt" in your soil

Your SoilKit test results will let you know how much sodium (Na) is in your soil. Sodium might ring a bell as a familiar element from the periodic table since it's in the chemical formula for table salt: sodium chloride. So by association, shouldn't a test result with high sodium be a salty, saline soil?

We have to be careful to define our terms here, because the same word might have a different meaning as a scientific term than in everday speech. Within our households, "salt" usually refers to sodium chloride in forms like table salt or road salt, since they're commonly found and close at hand. But in a science context, "salt" is a much broader term that includes all kinds of compounds made out of a combination of cations (positively charged particles) and anions (negatively charged particles). So yes, sodium chloride is a salt--but so is potassium chloride, sodium bicarbonate, ammonium sulfate . . . and many, many others!

When soil scientists talk about a saline soil, they are refering to a soil with high levels of salts overall, usually including sodium, calcium, and magnesium salts. This is officially measured with an electrical conductivity test, but the soil can show visual symptoms like salty white surface crust. If your soil has excessive levels of sodium specifically, the scientific term for this is a sodic soil, which is defined by sodium taking up 15% or more of the cation exchange capacity.

So if a "salty" soil comes up in conversation, you might want to confim whether you're talking about high salts in general or high sodium specifically! Click here to learn more about what causes high salinity and high sodium in soil.