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Geoecology: Soil Characteristics - Coggle Diagram
Geoecology: Soil Characteristics
Soil-forming factors
Parent material: original bedrock, affects the soil’s pH, colour and ability to hold water
Climate: controls the rate of weathering and biological activity
Topography: higher altitudes; leached thin soils, lower altitudes; deep fertile soils
Biological activity: decomposition of materials and aeration of soil
Human interference: fertilisers can be added and irrigation and drainage schemes can be set up, deforestation can remove organic material
Time: it takes 400 years to create 1 cm of soil, natural resource
Soil processes
Weathering: mechanical, e.g. freeze-thaw action, exfoliation or chemical, e.g. carbonation, hydrolysis, oxidation
Erosion: rivers, wind (aeolian), galciers
Leaching: soluble minerals and nutrients washed out of reach of plant roots, hardpan, waterlogging, soil infertile
Podzolisation: severe form of leaching, under coniferous trees, hardpans, soil infertile
Laterisation: severe form of leaching, tropical/equatorial regions, latosols or tropical red soils develop
Humification: decomposition of organic material to form humus
Calcification: low rainfall, capillary action, water to surface contains dissolved calcium, if soluble plant growth, if baked impermeable, creates chernozem soils
Salinisation: low rainfall, capillary action, water to surface contains dissolved salts, harmful to plants, toxic white salt pan
Classification of soils
Zonal soils
Intrazonal soils
Azonal soils
Brown earths (Irish soil)
Zonal soils under deciduous forest
Cool temperate oceanic climate
Most common Irish soil type
Fertile, dark brown, high humus
Crumb structure, loamy, slightly acidic, easily worked, productive
Biological activity, aerate and mix
Three types: acidic brown earths (low pH), podzolic brown earths (leached), shallow brown earths
Aridisols (subcontinental soil)
Hot dry conditions
Poorly developed
Light grey
Limited humus
Rapid growth after rainfall
Salinisation
Human interference with soil characteristics
The Burren, Ireland
Degradation of soil resources
Climatic: higher level of rainfall
Human factors: overgrazing and overcultivation
Gujarat and Rajasthan, India
Threat from soil erosion
Nearby Thar desert
Unpredictable monsoon rains
Deforestation
Cash crops
Monoculture
Desertification Case Study: The Sahel
Spreading of deserts
Rainfall levels decreased
Higher rates of evaporation
Lack of humus
Vegetation removed from marginal land
Higher birth rate and falling death rate
Semi-arid region
Savannah biomes to hot desert biome
Human interactions
Overgrazing
Cattle numbers have doubled due to population growth
Decrease in nomadic practices
Fallow year abandoned
Compaction of soil
Overcropping
Fallow year abandoned
HIPC, cash crops
Monoculture
Cultivating more marginal land
Deforestation
Population increase; demand for wood increased
Slash and burn
No reafforestation; too expensive
Soil conservation
Contour ploughing
Ploughing in line with the contours of the field
Reduce soil erosion
Improve water infiltration
Terracing
Steps built into steep slopes with small walls (bunds) at edge
Reduce gully erosion and leaching
Improve water infiltration
Shelter belts and strip farming
Growing trees to act as a barrier from wind around field
Afforestation and food supply if fruit trees are planted
Divide field into strips, alternate with different crops to prevent soil degradation
Stone lines
Stone lines placed along the contours of the field
Allow water infiltration
Prevent surface run-off
New breeds of animals
Better breeds reduce animal numbers
Prevent soil compaction and overgrazing