What property of soil is measured by the ribbon test?

The ribbon test assesses soil texture by measuring the relative proportions of sand, silt, and clay present in the soil. This test relies on the tactile ability to manipulate moist soil to form a ribbon between one’s fingers. The length and thickness of the ribbon formed provide insights into the soil's grain size distribution, which directly impacts various characteristics of the soil, such as its capacity to retain water, its drainage capabilities, and its fertility.

A well-formed ribbon indicates that the soil contains a significant amount of clay, while a shorter or crumbly consistency suggests a dominance of sand or silt. This test is particularly useful for categorizing soil into different texture classes, such as sandy, loamy, or clayey, which are important for understanding how a soil will behave in different environmental conditions and its suitability for various agricultural practices.