Which soil type is primarily composed of quartz and is chemically inactive?

The correct answer is that sand is the soil type primarily composed of quartz and is chemically inactive. Sand particles are typically larger than those of clay and silt, allowing sand to drain well and provide good aeration.

Quartz, being a very durable mineral, is resistant to weathering processes which makes sand largely composed of this material. As a result, sand exhibits low chemical reactivity compared to other soil types; the minimal chemical activity means it does not engage significantly in soil chemistry, which is important for plant nutrient uptake. This characteristic of sand makes it suitable for certain agricultural practices, especially in regions where a quick drainage is necessary.

In contrast, clay contains smaller particles that can hold water and nutrients well, but are more chemically reactive. Similarly, silt consists of intermediate-sized particles and has its own unique interactions within soil chemistry, while loam is a balanced mixture of sand, silt, and clay, which combines properties from all three types. While clay, silt, and loam play important roles in nutrient retention and moisture dynamics, it is sand's structure and composition that distinguish it as the model of quartz-rich, chemically inactive soil.