What are the three main sizes of soil particles?

The three main sizes of soil particles are sand, silt, and clay, which are fundamental categories used to describe the texture of soil. Sand particles are the largest, typically ranging from 0.05 to 2.0 millimeters in diameter, and they contribute to good drainage and aeration in the soil. Silt particles are intermediate in size, measuring between 0.002 and 0.05 millimeters. They retain moisture well and contribute to soil fertility. Clay particles are the smallest, with a diameter less than 0.002 millimeters, and they have a high surface area, which allows them to hold nutrients and moisture, but can lead to compaction and poor drainage.

This classification is important for understanding soil behavior, fertility, water retention, and the overall ecology of an area. Other choices include combinations of soil particle sizes that do not accurately reflect the standardized main categories used in soil science, making them less relevant for this context. For example, gravel is not considered a primary soil particle size in the same way as sand, silt, and clay.