In this section, you will learn: zz about the factors that influence soil formation.
Parent material Bacteria Fungi
Soil formation is influenced by a number of different factors which work together over a long period of time. These factors include:
• Climate • Parent material • Living organisms
• Landscape/relief • Vegetation • Time
The interaction of these factors leads to the formation of different soil types. ) Figure 16.7 The formation of soil
O A
Organic matter is broken down by living organisms.
Rain leaches minerals through the soil.
B
The type of vegetation is influenced by climate. Vegetation provides plant litter to form humus.
C
Unweathered parent material
Climate
The rate at which parent rock is broken down to form mineral matter by weathering depends on the amount of rainfall and the temperature. Too much rainfall can lead to leaching. Freeze-thaw action occurs in areas with cold climates, and chemical weathering helps to break down the parent rock in areas with hot climates.
Climate also has an impact on the type of vegetation that grows there. The type of vegetation controls the breakdown of living organisms and the formation of humus.
Parent material
Parent material refers to the type of rock that is broken down by weathering to form soil. The minerals from the broken-down rock provide nutrients for the soil. Soils that form on limestone are fertile.
ACT VITY
With your class: (i) Explain why soils that form on the bedrock of limestone are very fertile. (ii) Research the reasons why the acidity of the soil is important.
288
The parent material provides the mineral matter which gives the soil its nutrients.
