The nature of the soil profile may be such that it is fully developed or partially developed implying that soils may be deep or skeletal or soils of medium depth.
Soil profile development is influenced by a number of factors namely:
Nature of the parent rock The parent material is the nature of rock upon which weathering and other soil forming processes operate to create to create soil. In the first place the parent material provides the basis for soil profile development. It influences soil profile development in the following ways;
- Hard or resistant rocks lead to the development of thin soils i.e. with poorly developed profiles. On the other hand softer rocks are easily weathered and acted upon by other soil forming processes leading to the formation of deep soils with a well developed profile.
- The rocks with lines of weakness or joints have facilitated weathering and other soil forming processes leading to the formation of fairly deep soils. Such soils normally lead to a well-developed soil profile.
- Young parent material has led to poorly developed soil or poor soil profile while older rocks have had enough time to be weathered and to develop into well developed soil profiles.
- Permeable or porous rocks have enabled the easy infiltration of agents of weathering resulting into deep weathering and consequently deep soils with a well developed profile unlike impervious rocks.
Climate Rainfall and temperature determine the nature and rate of weathering and soil forming processes. Climate also determines the growth of plants and animals that contribute to the soil profile through weathering and through the addition of humus. Therefore different climatic conditions influence soil profile developments differently. In areas where the climate enhances weathering and other soil forming processes there is a well-developed soil profile.
Living organisms Vegetation provides the needed organic matter for the soils therefore a well-vegetated area has a better-developed soil profile. In addition, animals influence the mechanical break down of rocks therefore contributing to soil profile development. Man’s activities such as cultivation, mining, construction tend to physically weather rocks thereby contributing to the development of soil profile therefore areas of abundant biodiversity have a well developed soil profile as compared to those with limited biodiversity
Topography/Relief The nature or shape of the earth’s surface influences soil profile development. Highly or steeply sloping areas tend to have less developed soil profiles unlike areas of gentle slopes. This is because the rate of erosion is greater on the steep slopes and this removes the topsoil resulting into shallow or skeletal soils. On the other hand, in the gently sloping lands and generally flat lands, soil profile tends to be more developed i.e. there are deep soils.
Time It takes time for the soil profile to be fully developed. A typical or well developed profile of soil must have undergone adequate time, therefore the longer the time to which the rocks are exposed to weathering and other soil forming processes, the more the developed profile. Young rocks normally yield skeletal soils i.e. with poorly development profile