Calcareous soil is characterized by which of the following?

Calcareous soil is indeed characterized by the presence of sufficient free calcium carbonates. This type of soil typically contains more than 15% calcium carbonate, which can affect various factors like pH levels, nutrient availability, and overall soil structure. The presence of calcium carbonates can lead to higher pH levels, often rendering calcareous soils alkaline. This characteristic is significant because it influences the types of plants that can thrive in such conditions as well as how nutrients are held in the soil.

The other options don’t accurately describe calcareous soil. While some calcareous soils can have a neutral texture, their defining feature is the high content of calcium carbonates rather than a neutral texture per se. Similarly, the idea of low pH and high organic matter does not apply; in fact, calcareous soils tend to be more alkaline due to their calcium carbonate content. High iron content is not a strong attribute of calcareous soils; rather, it can be associated with different soil types influenced by iron oxides.