What percentage of rock fragments defines gravely soils?

Gravely soils are characterized by their composition, particularly in terms of the proportion of rock fragments they contain. Specifically, for soils to be classified as gravely, they must contain rock fragments in the range of 15% to less than 35%. This percentage is significant because it influences various soil properties, such as drainage, aeration, and nutrient availability. The presence of rock fragments impacts the soil's physical structure and its ability to retain moisture, which is essential for plant growth.

Soils with less than 15% rock fragments are usually considered sandy or silty, while those containing rock fragments in amounts greater than 35% may be classified as gravelly or even rocky soils, depending on the exact proportion. Thus, the classification of gravely soils as containing 15% to less than 35% rock fragments captures the balance necessary for defining this particular soil type. This understanding is critical for septic system design, soil management, and agricultural practices, as the characteristics of the soil affect how water and waste are managed within the ecosystem.