Final answer:
A Pallic soil with a fragipan typically includes the O horizon (organic matter), A horizon (topsoil), B horizon (subsoil with fragipan), and C horizon (parent material). The B horizon's fragipan is significant as it affects drainage and root penetration, which are critical factors in this soil type's fertility and agricultural use.
Step-by-step explanation:
Pallic soils are a delineated soil type found within certain geographical areas known for a specific soil horizon sequence. A typical Pallic soil with a fragipan may show a sequence similar to other soil types, but with its unique characteristics, especially the dense, hardpan B horizon known as the fragipan. The horizons here progress from surface litter down to the parent material and can be described as follows:
- O horizon - The uppermost layer, with freshly decomposing organic matter.
- A horizon - Also called topsoil, this layer consists of a mixture of organic material with inorganic products of weathering.
- B horizon - The subsoil, a dense accumulation of fine materials, contains the fragipan in this case.
- C horizon - The base of the soil profile, consisting of broken-down parent material.
The presence of the fragipan affects the drainage and root penetration within the soil, which is a vital characteristic that distinguishes Pallic soils from others. The B horizon in such a soil profile is particularly significant because of its potential impact on the overall soil's fertility and use in agriculture.