Brown earth Flashcards
Brown earth leaf litter
Deciduous forestry loses its leaves every year and so a thickerlayer of leaf litter builds up.
brown earth temperature
These soils are found in warmer climates which facilitates a faster decomposition of the leaf litter. Also means the soil does have biota
Brown earth humus
Faster decomposition of deciduous forestry (which is less acidic than coniferous trees) results in a thick, black/dark brown, mildly acidic MULL humus.
Brown earth processes
though the climate is warmer and drier, precipitation can still exceed evaporation in the winter months leading to leaching.
This leaching eluviates minerals like iron & aluminium out of horizon A and into Horizon B and may cause an iron pan to form.
In warmer summer months, evaporation can sometimes exceed precipitation.
This can lead to capillary action occurring, where water is being drawn up through the soil. This mixes the soil and improves fertility.
Brown earth soil biota
A greater number of soil biota means there is greater activity in the soil, leading to poorly defined horizons
Brown earth human use
The soil is also well aerated and more useful in farming as it is more fertile.
Brown Earth soils are among the most fertile soils in Scotland.
Brown Earth soils are better suited to farming because they are deeper, free draining and well mixed.
Brown earth nutrients
Roots are able to penetrate deeply into the soil, reaching the parent material nutrients, aiding nutrient recycling and improving fertility
Brown earth iron pan
The iron pan can then restrict drainage in a brown earth, potentially leading to water logging of the A horizon.
However, when no iron pan forms, water will drain through the soil freely (easily), improving fertility.
Question - explain the main conditions and processes involved in the formation of a brown earth soil (8m)
The natural vegetation of a brown earth soil is deciduous woodland. Deciduous trees lose their leaves on a seasonal basis (1)
resulting in a thick leaf litter layer of leaves and grass.(1)
The deciduous vegetation is mildly acidic and decomposes quickly in the warm/drier climate (1)
to form thick, dark brown, mildly acidic MULL humus (1).
Due to the warmer climate, there are many soil biota, resulting in a well mixed soil (1).
Soil biota mix and aerate the soil resulting in undefined horizons(1).
in winter, Ppt. often exceeds evap. in a brown earth, leading to leaching(1).
Leaching is when water moves down through the soil, elluviating iron and aluminium from A horizon and illuviating them into B horizon (1).
Iron builds up at the top of B horizon, forming a an impermeable “iron pan” (1).
The iron pan restricts drainage of water through the soil leading to water logging in the A horizon (1).
Where no iron pan develops, water drains freely through the soil, improving fertility(1)
In summer, capillary action can occur in a brown earth soil when ppt. is less than evap(1).
Water is drawn up through the soil, mixing the soil, improving soil quality (1).
