What substance is associated with high water conservation in terrestrial environments?

Uric acid is the substance associated with high water conservation in terrestrial environments. This is due to its unique chemical structure and properties that allow it to be excreted as a paste or solid, minimizing water loss. In contrast to ammonia, which is highly soluble and requires a significant amount of water to be excreted, uric acid is less toxic and can be concentrated, thereby conserving more water.

Urea, while more manageable than ammonia, is still water-soluble and thus involves a degree of water loss during excretion. Sodium chloride, on the other hand, is a salt that's not directly related to water conservation in the context of nitrogenous waste management. Given these properties, uric acid is particularly advantageous for organisms inhabiting dry environments, where water conservation is crucial for survival.