Post on 29-Jan-2021
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Soil Water Movement and Retention
Medium for plant growth
Regulator of water supplies
Recycler of raw materials
Habitat for soil organisms
Engineering medium
Functions of SoilFunctions of Soil
Functions of Soil
Medium for plant growth
Physical SupportGas exchangeWaterTemperatureNutrient source
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Functions of Soil
Regulator of water supplies
InfiltrationRun-offStorage/MovementDistributionPurification
Integral to hydrologic cycle
Total Earth WaterTotal Earth Water
OceansOceansIce and Glaciers Ice and Glaciers Aquifer/GroundwaterAquifer/GroundwaterAtmosphereAtmosphere
LakesLakes
SoilSoilRiversRivers
97%2.0%0.6%0.2%0.012%0.001%0.0002%
Water Movement
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Two Forces Responsible for Water Movement in Soils
Gravity
Capillarity
GravityGravity
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Capillarity
Spontaneous movement of waterinto and through pore spaces in soil
without the aid of gravity.
Adhesion and Cohesion
Cohesion
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Adhesion and CohesionAdhesion and Cohesion
oxygen
H
H
SURFACE
adhesion
oxygen
H
H
cohesion
Adhesion and CohesionAdhesion and Cohesion
adhesion
Cohesion(H-bonding)
Surface
Adhesion and Cohesion
Strong adhesion Weak adhesion
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Weak Adhesion
Adhesion to Soil Particles
Strong Adhesive Forces
Soil PoresSoil PoresAdhesion and CohesionAdhesion to the tube or pore wallCohesion between water molecules
Tube wall
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CapillarityCapillarity
Tube/Pore wall
}
Force down
h = 0.15r
CapillarityCapillarityh = 0.15
r
h
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Soil Pores and Pore Size Distribution
TextureDensityStructure
Define.
Particle Size Large/coarse Medium Fine/SmallSand
Loamy SandSandy Loam
Silt
Sandy clay LoamSilty clay Loam
Silt LoamLoam
Clay LoamSandy ClaySilty Clay
Clay
Pore Size Large/Macro Meso/Medium Micro/Small
Capillarity Weak Moderate Strong
Texture
Soil Pores
Sandy Silty Clayey
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Density
CompactionOrganic MatterArrangement of Particles Depth in Profile
Structure
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Sand
Clay
Water
Sand Clay
Initial Saturation
Uncompacted Compacted
Initial Saturation
Sandy Loam
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Aggregates
Wet Moist
Same Texture and Density
water
Relevance transpiration
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impervious
Water Water