Which of the following is not a renewable natural resource?

Concept

A renewable natural resource is replenished by natural cycles within a human-relevant timescale, provided its use does not exceed its rate of renewal.

A non-renewable resource forms so slowly that extraction reduces the available stock on practical timescales; most mineral deposits belong to this group.

Application

Classify each offered resource by asking whether a recurring natural process can restore it within a useful timescale. Air is renewed through atmospheric circulation, fresh water through the hydrologic cycle, and soil through weathering, organic-matter formation, and nutrient cycling. Salt is a mineral resource; deposits extracted as rock salt or brine are not replenished on a human timescale.

Contrast

• Clean air: atmospheric circulation and natural cleansing processes continually renew air quality, although pollution can overwhelm those processes.

• Fertile soil: weathering and biological nutrient cycling can rebuild fertility, but renewal is slow and requires careful management.

• Fresh water: evaporation, condensation, and precipitation replenish supplies through the hydrologic cycle, although local depletion remains possible.

• Salt: it is a mineral commodity whose economically used deposits are treated as non-renewable because geological replacement is negligible on a human timescale.

Cross-check

The same classification rule separates cycle-based resources from geological mineral stocks: air, soil, and fresh water have natural renewal pathways, whereas extracted salt stock does not have a comparable short-term replacement pathway.

Result

Therefore, the resource that is not renewable is salt.