HomeMy WebLinkAboutApplication Files_82693_pg0510 Physical Soil Properties-State of Connecticut CT Studios Project,South Windsor,CT
Available water capacity refers to the quantity of water that the soil is capable of '
storing for use by plants.The capacity for water storage is given in inches of water
per inch of soil for each soil layer.The capacity varies,depending on soil properties '
that affect retention of water.The most important properties are the content of
organic matter,soil texture,bulk density,and soil structure.Available water capacity
is'an important factor in the choice of plants or crops to be grown and in the design
and management of irrigation systems.Available water capacity is not an estimate
of the quantity of water actually available to plants at any given time..
Linear extensibility refers to the change in length of an unconfined clod as moisture
content is decreased from a moist to a dry state. It is an expression of the volume
change between the water content of the clod at 1/3 or 1/10 bar tension(33kPa or
10kPa tension)and oven dryness. The volume change is reported in the table as
percent change for the whole soil.The amount and type of clay minerals in the soil
influence volume change.
Linear extensibility is used to determine the shrink-swell potential of soils.The
shrink-swell potential is low if the soil has a linear extensibility of less than 3 percent; ,
moderate if 3 to 6 percent;high if 6 to 9 percent;and very high if more than 9 percent.
If the linear extensibility is more than 3,shrinking and swelling can cause damage
to buildings,roads, and other structures and to plant roots. Special design '
commonly is needed.
Organic matter is the plant and animal residue in the soil at various stages of
decomposition. In this table,the estimated content of organic matter is expressed ,
as a'percentage, by weight, of the soil material that is less than 2 millimeters in
diameter.The content of organic matter in a soil can be maintained by returning
crop residue to the soil.
Organic matter has a positive effect on available water capacity,water infiltration,
soil organism activity,and filth.It is a source of nitrogen and other nutrients for crops
and soil organisms. '
Erosion factors are shown in the table as the K factor(Kw and Kf)and the T factor.
Erosion factor K indicates the susceptibility of a soil to sheet and rill erosion by
water.Factor K is one of six factors used in the Universal Soil Loss Equation(LISLE) '
and the Revised Universal Soil Loss Equation(RUSLE)to predict the average
annual rate of soil loss by sheet and rill erosion in tons per acre per year.The
estimates are based primarily on percentage of silt, sand, and organic matter and '
on soil structure and Ksat.Values of K range from 0.02 to 0.69.Other factors being
equal,the higher the value,the more susceptible the soil is to sheet and rill erosion
by water.
Erosion factor Kw indicates the erodibility of the whole soil. The estimates are ,
modified by the presence of rock fragments.
Erosion factor Kf indicates the erodibility of the fine-earth fraction,or the material. '
less than 2 millimeters in size.
Erosion factor T is an estimate of the maximum average annual rate of soil erosion
by wind and/or water that can occur without affecting crop productivity over a
sustained period. The rate is in tons per acre per year.
Wind erodibility groups are made up of soils that have similar properties affecting
their susceptibility to wind erosion in cultivated areas. The soils assigned to group '
- - 1 are the-most-susceptible to wind-erosion,and those assigned to group-8 are the
least susceptible.The groups are described in the"National Soil Survey
Handbook." '
U Natural Resources Web Soil Survey 217/2010
Conservation Service National Cooperative Soil Survey Page 2 of 7