الفهرس 
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Abstract
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5_ s~y
Salt affected soils are those having excessive
concentrations of soluble salts and/or exchangeable sodium
sufficient to interrupt the growth of roost crop plants,
either directly due to the osmotic and specific-ion
toxicity effects or indirectly by changing the physicochemical
properties of the soil such as, poor water
permeability, poor aeration a.nd root penetration problems.
The area of salt affected soils in Egypt amounts to
800.000 ha (2 million feddans) concentrated in the
northern and eastern part of the Nile Delta. In addition.
the problem of salinity began to appear and did affect the
production of further 400.000 ha by varying degrees.
The present work aims at studying the effect of using
two different types of soil conditioners (Bitumen
emulsions and polyacrylamide solutions) at different
application rates on some hydrophysical and chemical
properties of some sa It at f ec t.ed soi Is of Egypt-
With this respect, three salt affected soils were
chosen in the presented study namely; A) saline non sodie
clay soil from the Agricultural Experimental Station of
the NRC at Shalakan. Qualubia Governorate, B) saline,sodic
clay soil from Sakha, Kafr El-Sheick Governorate a~q C)
sodie clay soil from Tal EI-Kebeir, Sharkia Governorate.
Examined soil conditioners were a) a locally
prepared Bitumen Emulsion (Bit I): 25% active material was
prepared in the filed from the Egyptian raw materials.
Bitumen (penetration 60/70) is produced by the EI-Nasr
petroleum company. at Suez and the non ionic commercial
type emulsifier (Misrofir 810) is produced by Misr
Petroleum Company, Factory of Alexandria. b) Humofina
Bitumen Emulsion. HA (Bit II): 50% active material
produced by Lapofina, Petrclfina, Brussels, Belgium. C)
Humofina polyacrylamide (PMll I) a low Mol.wt PAM solution
(Mol.wt 150.000-200.000) 16% active material produced by
Lapofina, Petrofina, Brussels, Belgium and d) a locally
prepared polyacrylamide (PAM II) a highly Mol.wt (mol.wt
1.360.000) 10% active material prepared in the
laboratories of NRC. Cctiro. Egypt. The rates of
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application in weight of active material of the conditioner
per 100 g of the dry soi.l-were0•.25, 0.5 and 1.0 for Bit
and 0.1 and 0.2 for PAM. The optimal conditions to make
the soil conditioning such as suitable initial and final
soil moisture content were 10-15% and 30-35% (on weight
basis), respectively.
Some physical and chemicdl characterists of the
affected soils under study as influenced by
conditioners were determined.
salt
soil
The results obtain can be summarized as follows:
1-’Effect of soi 1 conditioners on some physical properties
of the salt affected soils:
1. Stability of soil structure:
a- Micro aggregation
1- Soil micro structure expressed as percentages
of increase in the structural unit> 2 u . > 5 u , >
20 u. and > 50 u in diameter was improved in the
three examined salt affected soils by conditioning.
The effectiveness of both types of soil conditioners
on improving soil micro structure was enhanced by
increasing the amountB of conditioners applied. At
the same appl ication r-ate of PAM, the higher the
Mol.wt is. the more stable is the soil microstructure.
2- Idices which related both mechanical and
micro-structural anaLysis with the state of
structurization or dispersion namely; the structure
factor. the aggregation index. the dispersion ratio
and the dispersal index indicate the beneficial
effect of soil conditioners on improving soil micro
structure and on reducing its dispersability.
3- A considerable increase in the fraction silt
plUS clay not detached and remained in water stable
structure units> 0.02 mm in diameter was obtained.
The response of this parameter to the treatments was
similar to that of the micro aggregation.
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b- Macro aggregate stability:
1- Data of the size distribution of water-stable
structural units after wet sieving of the three
soils indicate improving of soil aggregation with
conditioning and with the amount of conditioners
appiied. Th response to PAM depends on its Mol.wt.
The polymer having high Mol.wt is more effective
than that having the lower one.
2- Soil conditionerE: increased the percentage of
water stable structural units> 0.84 rom, > 0.21 rom,
and > 0.105 rom in diameter. Conditioning the soil
enhanced the formation of the stable structural
uni ts > 2 rom in d t ame t.er at the expense of the
smaller ones. Formation processes increased with
increasing the amount of conditioners applied and
the Mol.wt of PAM.
3- The Mean weight diameter (MWD) of the stable
structural units increased with increasing the
application rate of the conditioner and the Mol.wt
of PAM. The response of the MWD to the applied
conditioners conside with that of the stable
structural units.
2. Volume expansion of the soil:
1- Soil swelling -measured by its water content - on
weight basis - at a hydrostatic suction of 15 mb
or by the change in its volume due to wetting to
this particular suction - was decreased by soil
conditioning.
2- The change in this soil property also increased
with increasing the amount of conditioners
applied. Polyacrylamide having the Mol.wt of
1.360.000 was more effective than that having the
Mol.wt of 150.000-200.000.
3- The response of hoth the saline sodie and the
sodie soil to soil conditioning was more clear
than that in the case of the saline soil. By
using 1.0% Bit and 0.2% PAM II. The decrease in
the swe llabil i ty of the sa 1ine sodie and the
sodic soi 1 reached about, 30 and 50%. respectively.
In the saline soil. this decrease reached
only about 13 and 20% by treating the soil with
the aforementioned conditioners, respectively.
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3. Hydraulic properties of soil under saturated
conditions:
1- Conditioning caused better changes in the
hydraulic properties of soils. Consequently, the
water movement through the soil under saturated
conditions would be facilitated.
2- The data indicated an increase in the
hydraulic conductivity, intrinsic permeability and
mean diameter of soil pores with soil conditioning.
The change in all the parameters under investigation
using both type of soil conditioners increased with
increasing the amount of conditioners applied. The
response of the parameters to conditioning process
was higher using PA.M having high Mol.wt relative to
that having low ones.
3- Transimissivity of the layered conditioned
soils for vertical flmo1 increased with the amount of
conditioners applied and took the same trend as that
of the other hydraulic properties. With this
respect. the studied conditioners could be arranged
in the following decreasing order: PAM II > PAM I >
Bit II ~ Bit 1.
4-~ The positive relation between soil micro
structure and its permeability as affected by soil
conditioning was insured from calculating some
indices namely; probable permeability, potential
permeabi 1ity and act.uel permeabi 1i ty.
4. The possibility of usina the conditioned salt
affected soils as drain filters:
Using the aggregate size distribution curves. the
three soils treated with different application
orates of the examined conditioners had been
evaluated as filter materials for drains according
to some set of filter criteria recommended by
Terzahi (1941), Juusela (1958), Winger and Ryan
(1970), Spadd 1ing (1970) and USDA (1971) to assure a
higher permeabi 1ity i:!Il1lediatenleyar drains and to
prevent its silting. According to the USDA (1971),
the acceptable filters were: the saline soil treated
with 0.5 and 1.0% bit or 0.1 and 0.2% PAM, the
saline or the sodie soils treated with 1.0% Bit, the
saline sodic soil treated with 0.2% PAM I or 0.1 and
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0.2% PAM II and the sadie soil treated with the high
Mol.wt PAM at the rate of 0.2%. Because the
hydraulic conductivity of the conditioned soils with
PAM was at least 10 times that of the untreated ones
regardless of the application rate of the
conditioner or its Mol.wt - they could be considered
as suitable filter mat.erial (Winger and Ryan, 1970).
On the other hand, adeque t e hydraulic conductivity
was insured when the saline soil was conditioned
with 0.25, 0.50 and 1.0% Bit. Moreover, treating
either the saline sadie or the sodic soil with 1.0%
Bit can achieve the goal. Conditioning the saline
soil with at least 0.25% Bit or 0.1% PAM would
assure a suitable filter criteria according to
Terzaghi (1941), Jllusela (1958) and Spaddling
(1970). On the other hand, classification of the
treated saline sodic or sadie as a drain filter
according to Spaddling (1970) is in good aggreement
with those of Terzaghi (1941) or Juusela (1958) with
minor exceptions. ’These exceptions include the
effective-ness of the 0.1% high Mol.wt PAM in the
saline sodic soil and 0.25% Bit I in the sodic soil.
Conditioning the soil situ and reusing the obtained
stable structural units as drain filters can replace
gravels or other filter materials and save their
costs and the expenses of their transportation and
grading.
2. Effect of soil conditioners on some chemical
properties of salt affected Boils:
1- All the paramet.ers under study, i.e. soil pH,
electrical conductivity, soluble ions in the
saturation paste extract, effective CEC,
exchangeable Na and surface area of the soil were
decreased by soil conditioning.
2- The higher the application rate of the
conditioner was, the lower were the values of the
mentioned properties.
3- the studied conditioners were arranged according
to their efficil~ncy in the following descending
order:
PAM (Mol.wt 1.360.00’0 > PAM (Mol.wt 150.000-200.000)
> Bit II (Petrofina, imported) ~ Bit I (locally
produced).
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4- Gypsum requirements of the ~aline ~o~ic.and
the sadie soils were decreased by SOli condItIonIng.
Instead of about 21 and 35 Tons/Fed for the saline
sadie and sodic soils, respectively, gypsum
requirements were reduced to reach about 13 Tons/Fed
for the saline sodic’soil and 20 Tons/Fed for the
sadie one using either 1.0% Bit or 0.2% PAM.
Therefore. using gypStun for reclaiming of saline
sodie and sadie soils would be facilitated by
conditioners application.
Obtained results were discussed on the basis of the
following:
1~ The aggregating action of both types of soil
conditioners and the formation of interparticle bridges
which depends on :
a) The mode of migration of active electrically charged
micelles of bitumen ~ as large organic molecules to
points of contact between soil particles or elay
tactoids. This is not only a matter of applied
quantity of the conditioner but also of the dilution
of its emulsion, t.he dispersion of emulsifier
rno lecules. the mois1.ure content of the soi I and
eventually of the method of incorporation.
b) The external and or internal adsorption of PAM
molecules and their distribution on or into clay
tactoids. This is mainly affected by the polymer
Mol.wt and the specific viscosity of its solution.
Hence, the particles will be fixed so tightly together
that the amounts of particle rearrangement possible may be
restricted and the swellability of the soil will be
largely impeded. Therefore. soil hydraulic properties will
be improved and water movement through the soil will be
greatly enhanced.
On the other hand. the coating effect of the conditioner
used (thickness and hardness) may decrease either
the contact between soluble salts in the soil and the
water used for extraction or the diffusion of water
through the obtained aggregates especially with the
hydrophobic Bit. This will lead to a decrease in
quantities of dissolved salts in the soil solution by
varying degrees according to the type of conditioner used
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and its application ra.te. The effect of PAM Mol.wt on
coating thickness and hardness must be taken into
considerations. The partially covering of soil particles
and tactoids and the occupation of the active sites of the
fixed cations by the applied products will lower either
the cation exchange capacity of the soil or its
exchangeable cations. Thus, gypsum requirements of the
soil will be decreased.