Soil or media containing calcium carbonate; a soil alkaline in reaction because of the presence or calcium carbonate
Merriam-Webster Online Dictionary
calcareous (adjective)1.
a) resembling or carbonate especially in hardness - calcite calcium
b) consisting of or containing calcium carbonate , also containing calcium
2.
growing on limestone or in soil impregnated with lime
calcareous (Wikipedia)
Calcareous is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.