Which property determines how easily water moves through soil?

• A. Permeability
• B. Texture
• C. Color
• D. Porosity

Answer: (A)

Permeability is the key idea. It describes how easily water can move through soil by looking at the interconnected pore spaces and how large they are. When the pore spaces are large and well connected—as in sandy soils—water flows through easily. When pores are small and tortuous—as in clay soils—water movement is much slower. Texture influences permeability because it determines those pore structures, but permeability is the direct measure of flow ease. Porosity, on the other hand, is about how much pore space there is (how much water the soil can hold), not how fast water moves. Color isn’t a reliable indicator of water flow. So, the property that determines how easily water moves through soil is permeability.