5.3 Soil degradation and conservation

Soil degradation

The physical, chemical and biological decline in soil quality, typically resulting in reduced biotic function

• Can be caused by human activities (overgrazing, deforestation, unsustainable agriculture

• Can also be caused by natural erosion

Overgrazing

When too many animals graze in the same area, removing the plantlife, causing the roots holding the dirt to die off, allowing for water and wind erosion to remove the soil.

Overcropping

The depletion of soil nutrients due to repeated agricultural use, causing dry soil, leading to erosion of topsoil.

Deforestation

Removal of forest, causing plants to die off, allowing for erosion to take place.

Unsustainable agricultural techniques

Techniques that can not be applied over a long period of time without a decrease in producitivty or increases of inputs, causing soil degradation

• Total removal of crops leads soil open to erosion

• Growing crops in rows allows water to flow eroding soil

• Irrigation will cause salinization, destroying soil

• Monocultures deplete soil of specific resources, removing its fertility

Urbanization

The increase in people living in towns, cities and settlements.

• Causes greater number of impermeable surfaces, causing greater amounts of runoff which causes soil erosion as well

Sheet wash

A type of soil erosion where large areas of surface soil are washed away during heavy storm periods and in moutainous areas moving as landslides.

Gullying

When channels develop on hillsides following rainfall, becoming deeper over time as soil is lost

Wind erosion

When the blowing of the wind on drier soils continuously remove the surface of the soil.

Shelter belts

A way to reduce wind erosion by planting trees and bushes between fields to reduce impact of wind.

Strip cultivation

Alternating low and high crops in adjacent fields

Cover crops

Fast growing crops to cover the soil either during non growing season or between food crops to reduce soil erosion

Terracing

A method to reduce the steepness of slopes by replacing the slopes with a series of horizontal terraces.

Plowing

Agricultural method which breaks up soil to increase drainage and to plant seeds but destroys microbial activity.

Contour farming

The process of plowing and cultivating along the contour lines (perpendicular to slope) to create terraces which traps water from eroding soil.

Trickle flow irrigation (drip irrigation)

A way of watering through a system of pipes that trickle water in drops, saving water.

Flood irrigation

Placing alot of water through trenches which drench the soil around them to grow plants (very ineffective waterwise)

Crop rotation

Changing the type of crop planted in an area every growing season to allow nutrients to be replenished and recover.