What is the correct approach to assessing coarse fragments when evaluating water retention?

In the context of evaluating water retention in soil, the correct approach is to ignore coarse fragments unless they exceed a certain threshold, which is typically around 15%. This is because coarse fragments, such as gravel and rocks, do not contribute to the soil's ability to retain water. Their presence can actually create air spaces that affect water movement and retention. By focusing attention on finer soil particles, such as sand, silt, and clay, which are responsible for holding moisture, assessments become more accurate in predicting water retention capabilities.

Coarse fragments represent a significant mass but offer minimal benefits to water retention due to their size and inherent properties. Thus, when evaluating water retention in soils, it's crucial to apply a threshold to these fragments to focus the assessment on the components that directly impact moisture retention. This approach enables soil judges to make informed decisions based on the soil's physical characteristics that truly influence its behavior in relation to water.