Which term best describes materials that enhance water holding capacity in soil?

The term that best describes materials that enhance water holding capacity in soil is soil organic matter. This material plays a crucial role in improving soil structure and fertility by increasing the soil's ability to retain moisture. Organic matter, derived from decomposed plant and animal materials, holds water like a sponge, which allows it to be available for plant roots and promotes overall soil health.

In contrast, sand particles typically have larger spaces between them, leading to quick drainage and minimal water retention. Clay minerals have small particle sizes and can hold water effectively, but their dense structure can also lead to waterlogging if not balanced with organic matter. Rock fragments do not contribute to water retention significantly as they do not retain moisture due to their size and lack of organic composition. Therefore, soil organic matter is the key component that enhances water holding capacity in soil.