Claypan

The formation of the claypan relates to a lack of vegetation coverage, soil particle size distribution, and high rainfall.

When the raindrops hit on bare soil with high energy, the fine sand, silt, and clay particles are re-arranged to plug all the pore spaces.

In the dry season, evaporation moves water from the deep horizon toward the soil surface through capillary action.

When the clay swells, the low saturated hydraulic conductivity prevents the vertical water infiltration to the deeper soil horizon.

[6] Since the claypan is acidic and clay-rich, there is high sorption of Al, K and Fe oxides to clay minerals.

Therefore, the claypan contains a cations-dominated zone that leads to a relatively high cation exchange capacity (CEC) to absorb and retain nutrients.

Plants with shallow roots, might not withstand the soil contraction forces due to the shrinkage of clay in the dry season.

Even though the total P content in the claypan is relatively high, they are strongly attracted by the clay particles that are not available for plant use.

Lamella clay-sandy soil
Water erosion. The common is crossed by a number of streams that have eroded rills like this into the soft soil. They become barriers to walking across the common, but also prevent excessive exploration by vehicles, which are technically banned.