Soil Degradation

3 reasons for natural soil erosion

1. rain - surface run off

2. wind erosion

3. rain splash

human causes of soil erosion

• overgrazing; cattle compact earth & rip grass out from the roots

• excessive ploughing downhill/too deeply

• cultivating deep slops

• organic matter reduced (less soil cohesion)

• biota reduction = less soil nutrients, less water retention

• stuck to machinery

• urbanisation

• deforestation

• increased extreme weather from climate change

• excessive use of agrochemicals

impact of deforestation on erosion

• exposes soil to wind erosion

• reduced interception

• roots don’t bind soil into peds

• mangrove deforestation increases turbidity, affecting coral reefs

impact of overgrazing on erosion

• stagnant water on top of soil

• high stocking density = soil compaction

• less interception

• increased wind blow erosion

impact of ploughing on erosion

• increased surface run off

• loosens soil, increasing wind blow erosion

impact of biota reduction on erosion

• agrochemicals kill non target species

• less aeration from biological mixing

• reduced breakdown of DOM

• less nutrient cycling

• less nitrogen fixation

• ploughning exposes biota to predators

• less DOM = easily movable peds

impact of cultivating steep slopes

• increased surface run off

• increased kinetic energy to transport soil

• increased desertification

solutions to deforestation causing erosion

• sustainable forestry

• crop rotation = retained interception

solutions to livestock causing soil erosion

• reduce stocking density

• move feeding stations

solutions to ploughing causing soil erosion

• ploughing horizontally

• crop rotation

solutions to reduced biota causing soil erosion

• minimising use of agrochemicals

• buffer zones like shelter belts/field margins

solutions to cultvation of steep slopes causing soil erosion

• creating buffer zones

• contour/horizontal ploughing

• terracing

• tied ridges band soil togethe