Which soil type is described as smooth and greasy?

The soil type described as smooth and greasy is clay soil. Clay soils are characterized by their very fine particles, which come together to form a dense and compact structure. When wet, these particles create a slippery and smooth texture that can feel greasy to the touch. This property is due to the high surface area of clay particles, which allows for significant water retention, making the soil sticky when disturbed.

In contrast, loamy soils are a mixture of clay, sand, and silt and typically have good drainage and fertility but do not exhibit the same greasy feel as clay alone. Sandy soils, composed of larger particles, feel gritty and drain well but lack the smooth and greasy characteristics associated with clay. Pedalfers, which refer to soils rich in aluminum and iron oxides typically found in humid regions, can have varying textures but do not consistently exhibit the smoothness described in the question. Thus, clay soils are correctly identified as the smooth and greasy type.