Describe and explain the characteristics of any one soil type you have studied. (2009 Q18, 80 marks)
In this answer I will discuss the characteristics of the Brown Earth soil. Brown Earth soils are known as a zonal soil as they developed as a result of the Cool Temperate Oceanic climate and the natural, mixed, deciduous vegetation of this climatic region. This climatic region is located between 30o and 55o North of the Equator. Brown Earths are the most common soil type in Ireland.
Brown Earth soils have a number of characteristics that make them different from other soil types. Characteristics of a soil include colour, texture, structure, and chemistry. These characteristics are determined by the immediate environment and by a combination of processes that are active in that environment.
As the name suggests, Brown Earth soils are brown in colour. Soil colour is determined by soil forming processes. Humification is responsible for the dark colour of the Brown Earth soils. Humification occurs when the organic matter on the surface of the soil is broken down and decomposed to form a substance called humus. The leaves of deciduous trees fall and decay in Autumn forming a layer of dark humus. This humus is washed into the soil by rainfall. The presence of this layer of humus makes Brown Earth soils very fertile The Brown Earth soils have a uniform colour throughout and have no distinct horizons. The Cool Temperate climate is warm enough for the presence of earthworms. Earthworms and other burrowers mix the soil together resulting in no distinct boundary between the A and B horizons.
Brown Earth soils have equal amounts of silt, sand and clay particles giving them a loamy texture. The texture of a soil describes how fine or coarse the particles of a soil feel. The loamy texture of the Brown Earth soil means that there is space between the soil particles for air and water to pass through it. This means that Brown...