Solonchaks occur where saline groundwater comes near to the surface, or where through evapo(transpi)ration salts from the soil water accumulate in the soil, e.g. in desert regions.
Soils having a salic horizon (horizon with accumulation of salts more soluble than gypsum) within 50 cm of the soil surface. They have no diagnostic horizons other than a histic, mollic, ochric, takyric, yermic, calcic, cambic, duric, gypsic or vertic horizon.
Solonchak with a crust of salt at shallow depth, China (Petrosali-Sodic Solonchak (Nudiyermic and Sulphatic);
ISRIC reference soil CN 14, download PDF)