Soil Science - 7. Soil Conservation and Management

Soil erosion

detachment and subsequent transport of soil
undesirable process in agriculture mainly because of losses

Mechanism of Soil Erosion
dispersion
raindrops splash soil sediments
supplied by kinetic energy

Entrainment

Mechanism of Soil Erosion
transport of suspended soil from upslope to downhill

Deposition

Mechanism of Soil Erosion
settles out under the action of gravity
rapid for sand
slow for clay

Geologic erosion

Types of Soil Erosion
natural rate
natural process

Geologic erosion

Types of Soil Erosion
smoothing downhill & mountains
1mm/yr = natural vegetation

Accelerated erosion

removal of topsoil

associated with human activities

10mm/yr

Raindrop

Forms of Soil Erosion
impact of raindrops

splashed at a longer distance

downslope

Sheet

Forms of Soil Erosion
removal of thin layer ‘sheet’

most widespread and most damaging

recognized soil deposition

Channel

Forms of Soil Erosion
water has concentrated > large mass

Rill channel

small channels
water washing down rows

Gully channel

advance rill erosion, increasing size of rills

Stream channel

carrying off the soil material on the side

Rainfall intensity

positively correlated to soil erosion
ratio of the total amount of rain (rainfall depth) falling during a given period to the duration of the period

Rainfall erosivity

the potential ability to cause erosion
an index that describes the power of rainfall to cause soil erosion

Soil erodibility

soil vulnerability to erosion
influenced by structural stability

Estimation of Soil Erosion

guide in selecting the most appropriate system and management practices

R

Estimation of Soil Erosion
rainfall positivity index

K

Estimation of Soil Erosion
soil erodibility

L

Estimation of Soil Erosion
slope length factor

S

Estimation of Soil Erosion
slope gradient factor

C

Estimation of Soil Erosion
cropping system and management factor

P

Estimation of Soil Erosion
erosion control practice factor

T

Estimation of Soil Erosion
tolerable soil loss

Cultural Soil and Water Conservation Measures

Conservation tillage
correction of soil problems

Biological Soil and Water Conservation Measures

Strip cropping (pilas-tanim)
Agroforestry

Soil and Water Conservation MeasuresMechanical

Terracing; broad channels
Grassed waterways
Pond