Soil Formation Processes

Soil Formation Processes

1. weathering

   • breakdown of rocks
   • rate
     • fast in hot & humid
   • mechanic
     • no change in characterisics from parent rock

2. Erosion

   • soil worn away by natural processes
     • rain
     • wind
   • human processes
     • deforestation
     • over-cropping
     • over-grazing

3. Leaching

   • washing minerals through soil
   • soil becomes infertile
   • hardpan forms

4. Humification

   • oxygen changes organic matter to humus
   • sped up by high temps & rain
     • rapid turnover in biomass into nutrients for plant growth
   • effective in tropical regions

5. Podzolisation

   • minerals dissolved by water
     • acidic podzols form
   • hardpan forms
     • waterlogging

6. Laterisation

   • iron oxide layer builds up bc of rapid weathering and leaching
   • latosols/red soils deveop
   • areas of heavy rain
     • minerals leached except iron
       • oxidation of exposed iron

7. Calcification

   • Calcium washed to B horizon
   • A horizon rich in humus
   • low rain, little leaching, little grassland veg
     • black earths form

8. Salinisation

   • capillary action brings salt to surface
     • salt layer
       • poisonous to plants
   • irrigation