Loamy soils contain sand, clay and humus | Types of Soil | Biology

This activity compares the composition of three soil samples simply by mixing them in water and letting them stand for a while, and observe their sedimentation behaviour. The sand comprises the hardest, densest, least soluble component so it settles to the bottom. The clay is finer and lighter so its the next layer up, while the organic matter - humus and compost - the parts that are essential for plant nutrition, are the lightest and float as the topmost layer.