im pretty sure ammonia is extremely rare to occur naturally, usually by microscopic decomposition and transformations in the soil.
infact i think all naturally occuring soluble bases are extremely rare relative 2 the acids. Most of these are produced by biological processes in living things and are mainly in the forms of HCO3 + and CO3 2+ ions, Also our blood is slightly basic. On the otherhand naturally occuring solid bases are quite common, including calcium carbonate, magnesium carbonate and many others found in rocks like limestone etc etc.