1. a zone near the soil surface, more or less cemented by secondary carbonates of Ca or Mg precipitated from the soil solution —note caliche may occur as a soft thin soil horizon, as a hard thick bed, or as a surface layer exposed by erosion 2. alluvium cemented with NaNO₃, NaCl, and/or other soluble salts in the nitrate deposits of Chile and PeruThis definition last updated 10/25/2008