What are clay soils and what do they look like?

Clay soils are identifiable by their solid appearance, and their red or brown color. This soil type consists of tiny particles that are 0.002mm in diameter, which makes the soil very dense and heavy. Additionally, this density makes it resistant to erosion and difficult for plant roots to penetrate. The water-holding capacity of clay soils is large due to their slow permeability. Clay particles carry a negative charge, which attracts positively charged nutrients like potassium and ammonium, preventing them from being lost through leaching as water moves through the soil. As clay soils have very little organic matter, the absorption and expansion of water further slows the soil's water flow.