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Topic 5.3: Soil Degradation and Conservation - Coggle Diagram
Topic 5.3: Soil Degradation and Conservation
Soil degradation
Types
Make the soil less suitable for use: Chemicals end up in the soil and turn the soil useless
Erosion: take away the soil, occurs when there is no vegetation, wind and water can take the soil away
Human activities
Overgrazing: the vegetation was eaten by cattle so the soil particles were no longer kept in place by roots and were blown away by wind => death of cattle.
Deforestation: the removal of forest. prone to erosion, most forests are in wet areas= the erosion will be due to water=> floods ( the leaves of trees deflect and slow down the progress of rain drops)
Unsustainable agriculture: techniques that cannot be applied over a long period without decrease in productivity or increased inputs of chemicals
removal of the crops after harvest => soil open to erosion
Growing crops in rows with uncovered soil in between=> erosion occur, crops are grown on a slop and the rows are in the direction of slope
Toxification: excessive use of pesticides
Irrigation: major part of water evaporates before reaching the crops=> minerals dissolved in the irrigation
Urbanization: land in cities and remove a source of agricultural land, increase run-off and may erode soil.
Soil erosion: a natural vegetation covers a soil, damage the soil structure. Leaves deflect heavy rain, roots holds soil together and humus absorbs large quantities of water
Gullying: channels develop on hillsides following rainfall. These channels become much deeper
Wind erosion: on drier soils with high wind remove the surface layer
Sheet wash: large areas of surface soil are washed away during heavy storm periods and in mountainous areas moving as landslides
Soil conservation
Addition of soil conditioner: typical soil conditioners are lime and organic materials. Lime has additional benefit of helping clay particles stick together so they act more like sand particles
Acid precipitation. Acid rain or snow means the water the drains through the soil is acidic
breakdown of organic matter releases carbon dioxide through respiration. This then dissolves into the soil water creating carbonic acid
Nitrification of ammonium ions to nitrate increases acidity
The removal of basic ions through leaching adds to soil acidity
Wind reduction: the effect of the wind can be reduced by planting trees or bushes or by alternating low and high crops in adjacent fields
Soil conserving cultivation techniques
Cover crops between the rows of main crops or between harvest and sowing can keep the soil particles in place
Terracing to reduce the steepness of slopes by replacing the slope with a series of horizontal terrace, separated by walls=> ruộng bậc thang
Plowing breaks up soil syructure and temporarily increases drainage