الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
This study was carried Out to investigate salinization
and alkalization processes in connection with movement
(downward or upward) of saline water through sOil columns
30-cm in height and 6 cm in diameter. Oownard movement
wasUlfluenc:ed by surface addit.ions whe’reas upward
movement ’was influenced by contacting bottoms of the soil
columns with saline ’water in a form of NaCl solution.
An empirical equation based On Gapon’s equation for
cation exchange equilibrium and similar to that of the U.S.
Salinity Laboratory was established to deduce ”ESP” as a
diagnostic value of salt-affected SOils by means of SAR of
soil extract at 1:5 SOil-water ratio. The reliabilities of
applying the equation obtained in this work and three
,other equations developed by u. S. Salinity Laboratory
(Richards, 1954), Balba (1962), and El-Arquan and Kaoud If 1981)
were examined. Other two equations were ~eveloped to
deduce ”ESP” through soluble (C0
3+ HC0
3) and pH of the
1:5 soil water extract.
To investigate the possibility that soluble anions
might in some way influence the cation exchange equilibrium
between adsorbed and soluble cations, samples of three
SOils and two clay minerals (presaturated with Ca or Mg)
were equilibrated with solutions of Na in the form of Cl
or 80
4
or C03• Also,·samples presaturated with Ca were
equilibrated with solutions of Mg in the form of Cl or
804• The preference of the investigated samples for Na,
Ca, and Mg was evaluated through calculating Vanselow’s
selectivity coefficient for Na-Ca, Na-Mg, and Mg-Ca
systems.The results may be presented as fol16ws:
1. With downward movement, soil salinity as well as soluble
exchangeable Na were highest in the top layer of the
soil column (0-10 cm) and lowest in the deepest one
(20-30 cm ), On the other hand, soluble and exchangeable
Ca, Mg, and K increased with depth. Bicarbonates and
chlorides underwent a pattern of distribution similar
to those of soil salinity and soluble Na, whereas
sulfates were comparatively lower in the top layer than
in the subsurface one.
Increasing concentration, as well as, the number of
applications of the saline water increased soil salinity,
seluble and exchangeable Na, soluble Cl and HC0
3, but,
in the same time, decreased soil content of soluble and
exchangeable Ca, Mg, and K and did not affect soluble 804•
2. With upward movement of saline water, salinity. as well
as , soluble Na were highest in the top layer, lowest
in the middle layer and intermediate in the bottom
One. However, exchangeable Na. and consequently
exchangeable Na percentage were lowest in the surface
and highest in the deepest layer. Soluble. as well as
exchangeable Ca. Mg. and K were highest in the surface
and decreased gradually with depth. Chlorides
aC;:~l!mu~ated in the top ”layers in amounts far greater.
than the layers below. Soluble bicarbonates underwent
an OPPOsite pattern,whereas soluble .suLfet es war!’!d’ist”’ibuted
within the soil column in a pattern similar to those
of soi L salinity and soluble Na ,
Increasing eoncent~ation of the saline water and duration
of its contact with the soil increased salinity of the SOil?
soluble and exchangeable Na. soluble Ca. Mg. K. and Cl.
On the other hand, increasing input of salt decreased
soil content of exchangeable Ca, Mg. and K. and did not
affect soluble HC0
3or S04
3. Deducing the ESP showed the following equations:
(a) ESP = 100 (0.0056 + 0.0311 SAR)
1 + (0.0056 + 0.0311 SAR)
(b) ESP = 0.9299 + 9.5037 (CO + HCO )
3 3(c) ESP = -92.0418 + 12.1571 pH
Correlating values of ESP calculated from equation (a)
as well as the other three similar equations developed
by u.S. Salinity Laboratory (Richards, 1954), Balba(1962)
and El-Arquan and Kaoud (1981) with actually determined
ESP supported the validity of using SAR for predicting
”ESp· of the soil with a reasonable degree of success.
Correlations between determined ESP and each of soluble
(C03 + HC03) and pH were highly significant indicating
the suitability of these parameters for predicting ESP.
4. There is specific anion effect on cation exchange
equilibria. The adsorbed Na was greater when the
assoc~ated anion was C03 rather thanCl or S04. Adsorbed
Na originated from the Na2S04 solution was greater than
that of the NaCl one. The variations became greater
with increasing salt concentration. The selectivity
coe.ff rcLent s calculated in terms of concentration ”Kv”
were higher with S04 as associated anion than with Cl.
The differences became less when selectivity coefficients
were calculated in terms of activi ty (Kvlt) but were not
eliminated.
For all the samples, the Mg-presaturated systems
adsorbed more Na than the Ca-presaturated ones. Also,
selectivity coefficients of the former systems were
always higher than the latter ones.
At e que Ivva Lue s of SAR, the corresponding values
of ESR in the case of S04 systems were higher than those
in the case of Cl systems. When SAR~ (calculated on
basis of activity) was used instead of ”SAR” (calculated
on basis of concentration) the differences were reduced
but did not disappeared.
Adsorption patterns of Mg were similar to those of
Na, however, at any equivalent fraction of the cation
(Na or Mg) in the equilibrium solution the corresponding
equivalent fraction of adsorbed cation in the Mg-Ca
systems was higher than in Na-Ca or Na-Mg ones, consequently
the preference of the investigated sample for Ca, Mg, and
Na followed the order, Ca> Mg.)..Na’