Topography has a significant impact on soil formation as it determines runoff of water, and its orientation affects microclimate which in turn affects vegetation. As the height of the land increases, the amount of precipitation, cloud cover and the strength of the wind also increase. Water erosion is more effective on steeper, un-vegetated slopes. The steeper the slope, there is a greater amount of water on these steep slopes, and the minerals are washed to the base of the slope, this can result in a very thin soil. This can encourage mass movement and land slides. The more gentle the slope, the slower the rate of water and water clogging, and there is little risk of soil erosion, but the risk of weathering is greatly increased. At the base of the slope, thick soils can be found.
The last factor that I will be looking at in this essay is time. Soil takes a very long time to develop, in regular conditions, for 10mm of soil, it can take up to 400 years, but in extreme conditions, it can take up to 1000 years for only 1mm of soil to be formed. For a regular soil suitable for farming, it can between 3000-12000 years for the soil to be formed. Newly forming soils tend to have many characteristics from their parent materials. After time, the soil gets new characteristics which are a result in the changing of the soil; these changes can be caused by an increase in the number of organisms, decaying plants and vegetation.
There are three different types of soil that I will be looking in this essay, Brown soil, Podzol and Gley soil. The first one out of these different soils that I will be looking at is Podzol.
Podzols are very common within the UK, and are highly common in the cooler wetter, upland areas, which are found in the north. An example where podzols are common are the Kinder Scout, in the Peak District, at 600m higher and 15000mm per year of precipitation, this area of the peak district is an ideal environment for Podzols. Podzols are also common in lowland areas where acidic conditions are created by the type of parent materials. Podzols occur in areas where precipitation greatly increases evapo-transpiration. The high intense rainfall that is acting upon the permeable acid parent rocks encourages intense leaching. As a result of this leaching, soil is generally very acidic, this increasing acidity results in low levels of soil fauna, another result of this acidity is that the horizons of the soil don’t mix which allows the horizons to have sharp boundaries. This increased acidity results in mor humus, and this creates a thick peaty layer on the soils surface. Litter takes a long time to decompose due to the temperature and the acidity, this results in fewer organisms. Plants that are common with podzol formations are coniferous plantations and moor land, podzols are generally not good for farming due to their high acidity, but are suitable to be used for the grazing of animals. The surface layers of podzols are very peaty because of poor organic decomposition under cold, wet and acid conditions.
Brown Soil is the most common type of soil which can be found in the UK due to it covers 40% of the UK, and is an excellent soil for agriculture. Brown Soil is common in a temperature range of -5˚C˚ to 30˚C and has a rainfall over 300mm and the evaporation is over 300mm. Brown soil is found in mid latitudes and a humid temperature. It is very common in deciduous woodland, due to their leaves falling I winter; these leaves decompose quickly and add to the nutrients in the soil. Brown soil is so called due to its brown colour. Brown soil is well-drained with a reddish-brown horizon that extends below 30cm in depth. The Surface A horizon has a very good nutrient content and has a rich multi-humus. Brown soil has blurry horizons, this is due to the soil being very well mixed as well as there being limited leaching under low precipitation areas. There is a large amount of micro and macro organisms in brown soil such worms and fungi, these help to mix the soil and add more nutrients to the soil.
Gley soils represent the most extensive soil cover in Scotland. These soils are found on gentler slopes or in areas of high rainfall where the water does not drain away very readily. All the glacial tills of central Scotland are dominated by Gley soils. The essential common feature of poorly draining Gley soils is that, under periodic or permanent water logging, the subsoil experiences a lack of oxygen within the pore space. Consequently under anaerobic conditions the insoluble iron oxides (which cause the characteristic yellow, brown or reddish-brown colour to soils with adequate aeration) are reduced chemically and the ferric iron changed to ferrous iron. Minerals with iron in the ferrous form impart a grey or bluish-grey colour to the subsoil. Due to the anaerobic conditions, water cannot pass through the soil; there is an increased amount of soil runoff. Due to these anaerobic conditions, there is no oxygen within the soil, there are poor living conditions for organisms to help add to the nutrient cycle, and as a result there is little decomposition. The little organic matter is very slowly decomposed in the soil.
There are many ways that humans can affect the soil. From farming to urbanisation to deforestation and a forestation. We can have both negative and positive impacts on the soil. One of the largest impacts that we have on soil is farming; some farmers don’t perform good practise on the soil, and can have a negative impact on the soils development and its makeup. Some farmers choose to use chemical fertilisers on their farmland to help increase the quality of their produce. As a result of this, the nutrients that are in the soil do not remain permanently, and after time, the quality of the soil can decrease and as a result vegetation will not grow as well on the agricultural land. Another result of farmers using chemical fertilisers is that it changes the chemical composition of the soil, and cannot benefit the crops long term. Despite this, there are some good impacts that farmers can have on soil; if the farmer leaves the field fallow for a year, then the nutrients that are lost to the vegetation can be replenished again with the decomposing vegetation. If a farmer doesn’t leave the field fallow for a year, the crops take up the nutrients from the soil, and as the vegetation is removed at harvest, the vegetation isn’t allowed to decay and thus add nutrients back to the soil. A good way of adding humus to the soil and increasing the nutrient content is by adding fresh compost to the soil, this is a very loamy and wet soil but is full of nutrients and small organisms. Ploughing also helps the soil as it encourages the soil to become more mixed as well as aerating the soil.
Different types of farming have different impacts on the soil, there are two different types of farming; pastoral farming, which is the grazing of animals such as cows and sheep on the farmers land, this type of farming is very good for the soil, as the animals droppings decompose and add nutrients to the soil as well as when the animals die, they decompose and can also add large amounts of nutrients to the soil. Arabic farming is the farming of crops on a field, this isn’t as beneficial to the soil as much as pastoral farming is, but if the plants where left to decompose, it would add large amounts of nutrients to the soil.
Trampling and footpath erosion can also have a large impact on soil; it results in a compaction of the soil and thus a reduction in pore space. As a result, there is less oxygen and less nutrients found in the soil, this also restricts the range of vegetation that can be found on footpaths.
Urbanisation is the last factor I will be looking at that affects soil in the UK. This results in very little vegetation as all the soil and land are covered with cement which is then used for building on. Due to the little vegetation, it can result in no humus and a very limited supply of nutrients to the soil.
In this essay I have looked at the five main factors that can affect soil; climate, parent material , Organisms, Topography and Time. I have looked at each factor individually and looked at how it can affect the type of soil. I have also looked into the three main types of soil found in the UK; Brown soil, Gley soil and Podzol. I have looked into each individual soil and seen what locations they are found in and what sort of environments they thrive in. I have also looked into the differences between these three types of soil. Finally, I looked into the main human factors that can affect soil; Farming, Urbanisation and Trampling and footpaths.