Which property governs the amount of water a specific soil can retain?

The property that governs the amount of water a specific soil can retain is porosity. Porosity refers to the volume of voids or pores in the soil compared to the total volume of the soil, expressed as a percentage. Higher porosity indicates that there is more space available within the soil for water to be retained.

Porosity is critical because it directly influences the soil's ability to hold water, which is essential for plant growth and the overall health of ecosystems. Different soil types possess different porosities; for instance, sandy soils have larger spaces between particles but lower porosity compared to clay soils, which have smaller particles but can retain more water due to their higher surface area and compactness.

While permeability is the ability of soil to transmit water through its pore spaces, it does not indicate how much water the soil can hold. Density relates to the mass of soil per unit volume and does not directly correlate with water retention. Cohesion refers to the attractive force between similar molecules, which is more relevant in discussions of soil strength and stability than water retention.