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The salt concentration in the water extracted from a
saturated soil (called saturation extract) defines the salinity
of this soil. If this water contains less than 3 grams of salt
per litre, the soil is said to be non saline (see Table below). If
the salt concentration of the saturation extract contains
more than 12 g/l, the soil is said to be highly saline.
g/l
0-3
3-6
6-12
>12
millimhos/cm
0-4.5
4.5-9.0
9.0-18
>18
Salinity
Non saline
Slightly saline
Medium saline
Highly saline

Soil salinity is the salt content in the soil; the
process of increasing the salt content in soils is
known as Salination. Salt is a natural element of
soils and water. Salination can be caused by natural
processes such as mineral weathering or the
gradual withdrawal of an ocean. It can also be
caused by artificial processes such as irrigation.
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The excess accumulation of salts, typically most
pronounced at the soil surface, can result in saltaffected soils. Salts may rise to the soil surface
by capillary transport from a salt-laden water table
and then accumulate due to evaporation. They can
also become concentrated in soils due to human
activity, for example the use of potassium as
fertilizer, which can form sylvite, a naturally
occurring salt. As soil salinity increases, salt effects
can result in degradation of soils and vegetation.
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Most crops do not grow well on soils that contain
salts.
One reason is that salt causes a reduction in the
rate and amount of water that the plant roots can
take up from the soil Also, some salts are toxic to
plants when present in high concentration. Some
plants are more tolerant to a high salt concentration
than others. The highly tolerant crops can
withstand a salt concentration of the saturation
extract up to 10 g/l. The moderately tolerant crops
can withstand salt concentration up to 5 g/l. The
limit of the sensitive group is about 2.5 g/l.
Highly tolerant(10 g/l)
Date palm
Barley
Sugar beet
Cotton
Asparagus
Spinach
Moderately tolerant(5 g/l
Wheat
Tomato
Oats
Alfalfa
Rice
Maize
Flax
Sensitive(2.5 g/l)
Red clover
Peas
Beans
Sugarcane
Pear
Apple
Orange
Potatoes
Prune
Carrot
Plum
Onion
Almond
Cucumber
Apricot
Pomegranate
Peach
Fig
Olive
Grape

Alkali, or alkaline, soils are clay soils with high pH (>
8.5), a poor soil structure and a low infiltration capacity.
Often they have a hard calcareous layer at 0.5 to 1 metre
depth. Alkali soils owe their unfavourable physicochemical properties mainly to the dominating presence
of sodium carbonate which causes the soil to swell and
difficult to clarify/settle. They derive their name from the
alkali metal group of elements to which
the sodium belongs and that can induce basicity.
Sometimes these soils are also referred to as (alkaline)
sodic soils.Alkaline soils are basic, but not all basic soils
are alkaline.
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The natural cause is the presence of soil minerals
producing sodium carbonate (Na2CO3) and sodium
bicarbonate (NaHCO3) upon weathering.
Agricultural problems
Alkaline soils are difficult to take into agricultural
production. Due to the low infiltration capacity, rain
water stagnates on the soil easily and, in dry periods,
cultivation is hardly possible without copius irrigated
water and good drainage. Agriculture is limited to crops
tolerant to surface waterlogging (e.g. rice, grasses) and
the productivity is low.
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Irrigation water quality:
In irrigation agriculture, the quality of water used for
irrigation should receive adequate attention. Irrigation water,
regardless of its source, always contains some soluble salts in
it. Apart from the total concentration of the dissolved salts,
the concentration of some of the individual salts, and
especially those which are most harmful to crops, is
important in determining the suitability of water for
irrigation. The constituents usually determined by analyzing
irrigation water are the electrical conductivity for the total
dissolved salts, soluble sodium percentage, sodium absorption
ratio, boron content, PH, cations such as calcium,
magnesium, sodium, potassium and anions such as
carbonates, bicarbonates, sulphates, chlorides and nitrates.
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Water from rivers which flow over salt effected areas or in the
deltaic regions has a greater concentration of salts sometimes
as high as 7500 ppm or even more. The quality of tank or lake
water depends mainly on the soil salinity in the water shed
areas and the aridity of the region. The quality of ground
water resources, that is, from shallow or deep wells, is
generally poor under the situations of
high aridity
high water table and water logged conditions
in the vicinity of sea water
on the basis of suitability of water for irrigation, the water
may be classified under three categories,
Class
Electrical
Conductivit
y
(microohm/cm)
Total
Dissolved
Solids
(ppm)
Exchangea Chlorid
ble sodium e
(percentage (ppm)
)
Sulphates
(ppm)
Boron
(ppm)
Remarks
I
0-1000
0-700
0-60
0-142
0-192
0-0.5
Excellent to
good for
irrigation
II
1000-3000
700-2000
60-75
142-355 192-480
0.5-2.0
Good to
injurious;
suitable only
with
permeable
soils and
moderate
leaching.
Harmful to
more sensitive
crops
III
>3000
>2000
>75
>355
>2.0
Unfit for
irrigation
>480
 An
agricultural land is said to be waterlogged when
its productivity or fertility is affected by high water
table. The depth of water-table at which it tends to
make the soil water-logged and harmful to the
growth and subsistence of plant life depends upon
the height of capillary fringe, which is the height to
which water will rise due to capillary action. The
height of capillary fringe is more for fine grained
soil and less for coarse grained ones.

Usually known as reclamation, and also known as land
fill (not to be confused with a landfill), is the process of
creating new land from ocean, riverbeds, or lake. The land
reclaimed is known as reclamation ground or land fill. A
related practice is the draining of swampy or seasonally
submerged wetlands to convert them to farmland. While this
does not create new land exactly, it allows commercially
productive use of land that would otherwise be restricted
to wildlife habitat. It is also an important method
of mosquito control.