Soil catena is the successive arrangement or sequence of arrangement of differing soil types along the slope from the hill top (summit) to the valley bottom.
This sequence varies with relief and drainage though it may be derived from the same parent material e.g. the soils at the valley bottom are likely to be different from those of the hill top
The factors influencing the development of soil catena:
Relief: which is the physical appearance (morphology) of the landscape affects or influences the development of soil catena in such a way that differences in relief affect the nature or soil type due to the fact that they influence erosion, deposition and human activities.
- Hill tops have lateritic capping with the resultant thin/ skeletal soils.
- The very steep slope/free face hardly has any soil i.e. has bare rock.
- The waxing slope/ convex slope is characterised by coarse, stony, creep soils due to erosion.
- The waning slope is fairly deep with clay loam soils.
- The low lying area/ valley bottom has fine particles of clay. It is deep and poorly drained. It is generally a zone of deposition or illuviation i.e. zone of accumulation.
The steep slope encourages erosion and hence has shallow soils. The gentle slopes are well drained and experience some down slope translocation of soil particles while the valley bottom experiences deposition hence accounting for the deep soils.
Climate: Influences the development of soil catena in the following ways:
- Heavy rainfall encourages erosion on the upper slopes (waxing slope) and deposition on the lower slopes and valley bottom.
- Heavy rainfall also encourages leaching leading to the development of lateritic soils along the waxing slope.
- Heavy rainfall also leads to flooding in the valley bottom and lower slopes resulting into clayey water logged soils.
Living organisms: These include plants, animals and man.
- Well vegetated areas lead to development of the loamy soils or those with adequate humus especially on the middle and lower slopes.
- Forested slopes check on the rate of soil erosion hence influencing the depth of the soil.
- Man’s activities like deforestation and cultivation encourage erosion thereby leading to thinner soils especially on the steeper slopes while on the other hand encouraging deposition on the lower slopes and the valley bottom.
Nature of the parent rock: The differences in the soil types along the slope could be as a result of them having developed from different parent materials.
Time: The development of soil catena needs ample time. The processes involved take long and therefore the longer the geological time scale, the more developed of soil catena of an area.