Themes > Science > Earth Sciences > Geology > Soils > Soil Morphology > Soil Morphology > Consistence

Consistence refers to the cohesion among soil particles and adhesion of soil to other substances or the resistence of the soil to deformation. Whereas soil structure deals with the arrangement and form of peds, consistence deals with the strength and nature of the forces between particles. Consistence is described for three moisture levels: wet, moist, and dry. The stickiness describes the quality of adhesion to other objects and the plasticity the capability of being molded by hands. Wet consistence is when the moisture content is at or slightly more than field capacity. Moist consistence is a soil moisture content between field capacity and the permanent wilting point. When recording consistence it is important to record the moisture status as well. Cementation is also considered when consistence is described in the field. Cementing agents are calcium carbonate, silica, oxides of iron and aluminium.

Table 9.7.1. Classification of consistence (Buol et al., 1997).

Moisture status

Consistence

Abbreviation

Description

wet

Nonsticky

wso

Almost no natural adhesion of soil material to fingers

 

Slightly sticky

wss

Soil material adheres to only one finger

 

Sticky

ws

Soil material adheres to both fingers

 

Very sticky

wvs

Soil material strongly adheres to both fingers

 

Nonplastic

wpo

No wire is formable by rolling material between the hands

 

Slightly plastic

wps

Only short (< 1cm) wires are formed by rolling material between the hands

 

Plastic

wp

Long wires (>1cm) can be formed and moderate pressure is needed to deform a block of the molded material

 

Very plastic

wvp

Much pressure is needed to deform a block of the molded material

 

Moist

Loose

ml

Soil material is noncoherent

 

Very friable

mvfr

Aggregates crush easily between thumb and finger

 

Friable

mfr

Gentle pressure is required to crush aggregates

 

Firm

mfi

Moderate pressure is required to crush aggregates

 

Very firm

mvfi

Strong pressure is required to crush aggregates

 

Extremely firm

mefi

Aggregates cannot be broken by pressure

Dry

Loose

dl

 

 

Soft

ds

 

 

Slightly hard

dsh

 

 

Hard

dh

 

 

Very hard

dvh

 

 

Extremely hard

deh

 

Cementation

Weakly cemented

cw

 

 

Strongly cemented

cs

 

 

Indurated

ci

 


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