A calcareous soil is soil that has calcium carbonate (CaCO3) in abundance. If a calcareous soil has hydrochloric acid added to it, the soil will effervesce and give off carbon dioxide and form bubbles because of the chemical reaction. Calcareous soils are most often formed from limestone or in dry environments where low rainfall prevents the soils from being leached of carbonates. Calcareous soils frequently cause nutrient deficiencies for many plants.
calcareous soil (kălkâr´ēəs), soil formed largely by the weathering of calcareous rocks and fossil shell beds. Different varieties usually contain chalk, marl, and limestone and frequently a large amount of phosphates. They are often very fertile, as in the case of the buckshot soils of the S United States. Sometimes calcareous soils are flinty, thin, and dry. They often form a large part of the soil of deserts, which may prove very fertile when sufficient moisture for crops is applied.