If soil has an EC of 6.0 mmhos/cm and contains 20% sodium on the CEC, it is a _________ soil.

In assessing soil classification, the electrical conductivity (EC) and sodium content relative to the cation exchange capacity (CEC) are critical factors. A soil with an EC of 6.0 mmhos/cm signifies significant salinity, as this level typically indicates high salt concentration.

Furthermore, the fact that the soil contains 20% sodium on its CEC is a determining characteristic for classifying it as saline-sodic. When more than 15% sodium saturation is present in a soil with relatively high salinity (evidenced by an EC above 4 mmhos/cm), it qualifies as saline-sodic. This condition reflects the combined effects of both excess salts and sodium.

The classification system identifies saline soils primarily based on their salinity levels without significant sodium impact. Non-saline soils would exhibit neither a high EC nor high sodium levels. The term "wet" does not directly relate to sodium content or salinity classification in this context.

Thus, due to the high electrical conductivity coupled with the notable sodium proportion, the appropriate classification for this soil is saline-sodic.