الفهرس 
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Abstract
113
5. SUMMARY
This study deals mainly with the assessment of salt-affected soils and the
role of the clay fraction in such assessment. Two natural soils, extremely
differing in their texture, were selected from two locations in the:south of Delta,
Tukh district i.e. Moshtohor (:,:58% clay) and Meet Kinana (:: 96% sand) to
develop the soil models needed for the study. Soil samples of both locations
were treated with NaCl + CaCh to obtain salinity grades corresponding to BC
values of 2.75, 4, 8,12,16,20 and 24 d8m-l. Following to SOJil salinization, a
sodication process was performed using NaOH solution to obtain seven levels
of sodicity corresponding to E8P values of 10, IS, 20, 25, 30,40 and 50,
through each of the abovementioned grades of soil salinity. Therefore the three
categories of salt-affected soils i.e, sodic and saline-sodic soils were
represented through the prepared soil models.
The role of the clay fraction on the hazardous effects due to salinity
and/or sodicity was evaluated in soil models derived from the aforementioned
soils; by mixing each model derived from one soil, in increasing ratios, with the
corresponding model of the other soil i.e, of the same salinity and sodicity
levels. Accordingly, eight different grades of soil texture having clay content
values of 2.32% (81), 7.77% (82), 16.12% (83),24.46% (84),32.82% (85),
41.47% (86), 49.52% (87) and 57.98% (88) were obtained through each grade
of salinity (7) or sodicity (7).
Moreover, seventy samples representing the naturally saht-affected soils
111 E&’Yptwere collected from different locations, adjacent to the bitter lakes in
the east to the Delta and lakes of Manzala, Burullus, Edku and Mariut at Delta
northern coasts.
Both prepared soil models and naturally salt-affected soils were subjected
to the routine analyses; EC, exchangeable cations and CEC as well as ESP and
hydraulic conductivity (K).
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A greenhouse trial was carried out using both prepared and natural saltaffected
soil samples as growth media, where barley plants (Giza 123) were
grown for 45 days, thereafter. dry matter yield, as well as plant content and
uptake of N, P, K, Na, Ca and Mg were estimated.
The obtained data were subjected to statistical analyses and the different
interrelationships describing the prepared soil models were estaliblished.
The validity of soil parameters and equations developed for the
assessment of salt-affected soils was evaluated by computing the values of
D.M. yield of barley plants predicted for the naturally salt-affected soils.
Significancy of differences were estimated between the values of predicted yield
(calculated) and those of actual yield of naturally salt affected soils were
estimated by means of ”ANOVA” test.
The obtained results can be summarized in the following:
1- Soil salinity in relation to soil characteristics and producrivlty:
A. Hydraulic conductivity (K):
Results of (K) in tested soil models as affected by salinity and clayo~
reveal that:
1. Values of the relative hydraulic conductivity increased at a rate of about
1.70% per each unit of increase in soil salinity above EC 4 dSmwl•
2. K values is negatively and significantly (r=-0.913***) affected with
increasing the clay content of soils.
3. The combined effect of soil salinity and clay content on K is described by
the equation;
K = 9.67 + 0.0559 EC - 6.61 log clay (R = 0.921***)
B. Soil pH (in 1:2.5 soil:water suspension):
pH values of tested models in relation to soil salinity and clay% reveal
the following:
115
1. Soil pH was significantly (r = -0.706***) reduced as the soil salinity
increased (at a rate of about 0.03 pH unit for each Eee unit above of 4
dSm-l.
2. Soil pH was significantly (r = -0.587···) decreased with increasing the clay
fraction%. Each increase of 1.%in the clay content of the soil, above 2.32%,
reduced soil pH by:: 0.01 unit.
3. The combined effect of the soil salinity and the the clay content on soil pH
is represented by the equation;
pH = 8.62 M0.034 EC - 0.0104 clay (R = 0.920***)
C. Results of the elemental content of barley plants grown on tested saline
models showed the following:
1. NMcontent of plants decreased with increasing soil salinity at all levels of
soil salinity except those of ECe 16 and 20 dSm-l, as compared by the
control treatment.
2. N-content of plants slightly but gradually increased with increasing the soil
content of clay.
3. Pvcontent of plants decreased with increasing soil salinity.
4. Clay presence at any level tested, failed to affect clearly the PO..!o of plants
under the different levels of soil salinity.
5. K-content of plants was adversely and gradually affected with increasing
soil salinity. Values of K-content were reduced, on average, from 4.4% to
2.5% for the highest level of salinity (EC 24 dSm-I).
6. K-content of plants tended to increase steadily, with increasing the clay
content of soil models.
7. Na-content of plants was positively affected by increasing soil salinity, but
was progressi vely reduced by increasing the clay content.
8. Ca-content of plants consistently increased with increasing soil salinity as
well as with increasing the clay content.
9. Mg-content of plants was positively affected by increasing soil salinity to
more than Eee 8 and up to 24 dSm-l
, but did not show clear trend due to the
increase in the clay fraction.
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D- Results of the elemental uptake by barley plants grown on tested saline
models reveal the following:
1. The total ,uptake of all the -tested elements was high significantly decreased
with increasing soil salinity due to its adverse effect on dry matter yield.
2. The total elemental uptake ,was positively affected by increasing the clay
content according to the following equations:
N-uptake = 34.60 + 1.120 clay
·P-uptake = 6,11 + 0.216 clay
K-uptake = 37.30 + 1.210 clay
Na-uptake = 13.90 + 0.185 clay
Ca-uptake = 14.90 + 0.484 clay
Mg-uptake = 9.26 + 0.243 clay
3. The combined effect of soil salinity and clay
uptake can be described by the equations:
N-uptake = 83.20 - 3.45 EC + 1.120 clay
P-uptake = 21.40 - 1.09 EC + 0.215 clay
K-uptake = 116.00 - 5.59 EC + 1.200 clay
Na-uptake = 22.20 - 0.596 EC + 0.185 clay
Ca-uptake = 23.20 - 0.591 EC + 0.484 clay
Mg-uptake - 11.40 - 0.155 EC + 0.243 clay
(r = 0..636***)
(r = 0.445**)
(r = 0.491***)
(r = 0.549***)
(r = 0.811 ***)
(r = 0.786***)
content on total elemental
(R = 0.960***)
(R = 0.937***)
(R = 0.968***)
(R = 0.849***)
(R == 0.888***)
(R = 0.807·**)
E- Dry matter yield (D.M.) of barley plants grown on the tested soil models
showed the following trends:
I. D.M. yield gradually and significantly decreased (by about: 0.13 g/pot) for
each unit of increase in EC more than 4 and up to 24 dSm-1 according to the
equation.
D.M. yield =4.16 ’- 0.141 EC (r = -0.813 ••• )
2. The clay fraction soundly decreased the adverse effect due to soil salinity on
the n.M. yield which increased regularly under all the salinity levels, with
increasing soil content of clay as described by the equations:
n.M. yield = 1.20 + 0.0338 clay (r = 0530”’)
n.M. yield = 3.18 - 0.141 EC + 0.0338 clay (R = 0.970* •• )
11- Soil sodicity in relation to soil characteristics and productivity:
A. Hyd raulic conductivity (K):
Results of the hydraulic conductivity (K) in the tested soil models as
affected by sodicity and clay% reveal that:
1. The relative hydraulic conductivity was progressively reduced either as the
soil sodicity or the clay content increased according to the equation;
K = 4.45 - 2.54 log clay - 0.0184,ESP (R = 0.862***)
B. Soil pH (in 1:2.5 soil:water suspension):
pH values of the tested soil models in relation to soil sodicity and clay%
showed the following:
I. Soil pH significantly (r = 0.877***) increased with increasing soil sodicity
(by 0.03 pH unit for each ESP unit), according to the equation;
pH = 8.22 + 0.0307 ESP (r = 0.877***)
2. The clay fraction significantly (r = -0.427**), but negatively, correlated with
soil pH, at a rate of about 0.011 unit versus each increase of 1% in clay
(above 2.32%). This compo sited relation is represented the equation;
pH = 8.52 + 0.0307 ESP - 0.0105 clay (R = 0.975···)
c. Plant contents of elements showed the following trends:
I. The N, P, K, Ca and Mg in barley plants significantly and gradually
decreased, but Na increased with increasing soil sodicity.
2. Plant content of N, K, Ca and Mg increased with increasing soil content of
clay, while PO.lo and Na% slightly decreased.
3. The combined effect of soil sodicity and clay% on elemental content of
plants can be described by the equations:
N% = 2.540 + 0.0106 clay% - 0.0020 ESP
PO.lo :: 0.799 - 0.0006 clay% - 0.0046 ESP
K% = 3.970 + 0.0090 clay% - 0.0540 ESP
Na% = 0.372 - 0.0044 clay% + 0.0439 ESP
Ca% = 0.786 + 0.0064 clay% - 0.0088 ESP
MgOfc) = 0.555 + 0.0010 clay% - 0.0056 ESP
(R = 0.621···)
(R = 0.663···)
(R = 0.973···)
(R = 0.995···)
(R = 0.946···)
(R = 0.826···)
lIS
D- Results of total elemental uptake by barley plants grown on the tested
sodic soil models reveal the following:
1. Plant Uptake ofN, P, K, Ca and Mg sharply decreased with increasing soil
sodicity, while Na-uptake significantly increased as the soil sodicity
increased.
2. Elemental uptake of barley plant was positively affected with increasing the
clay content.
3. The combined effect due to the soil sodicity (ESP) and clay content (0/0) on
elemental uptake is repesented by these equations;
Nsuptake = 78.70 - 1.040 ESP + 1.290 clay
P-uptake = 21.60 - 0.296 ESP + 0.231 clay
K-uptake = 111.00 - 2.230 ESP + 1.300 clay
Na-uptake = 5.29 + 0.896 ESP + 0.395 clay
Ca-uptake - 22.20 - 0.441 ESP + 0.466 clay
Mg-uptake - 15.70 - 0.275 ESP + 0.187 clay
(R = 0.989***)
(R = 0.926·**)
(R = 0.983***)
(R = 0.846***)
(R = 0.973***)
(R = 0.933-*-)
E. Dry matter yield (D.M.):
Results of D.M.’ yield of barley plants grown on sadie soil models
showed the following trends:
1. D.M. yield was significantly (r = -0.478**) reduced with increasing soil
sodicity, at rate of about 0.03 g/pot for each ESP unit. The relationship
between D.M. yield and soil sodicity is described by this equation:
D.M. yield = 3.77 - 0.0262 ESP .(r = -0.478**)
2. The clay fraction presence diluted the adverse effect of soil sodicity on
n.M. yield of barley plants and consequently increased regularly this yield.
at a significantly (r = 0.858·_·) increased with increasing the clay content,
at a rate of about 37 mg/pot for each 1% of the clay content.
3. The relationship between D.M. yield and the clay content is.described by
the equation:
D.M. yield = 1.96 + 0.0374 clay (r = 0.858*·*)
4. The composited relation ofD.M. yield with ESP and clay% lisrepresented
by the equation:
D.M. yield = 2.68 - 0.0262 ESP + 0.0374 clay (R = 0.983***)
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IIl- Combined effect of soil salinity and sodicity of soils on their
characteristics and productivity;
A. Hydraulic conductivity (K):
The obtained trends for hydraulic conductivity under saline-sodic
conditions are swnmarized in the following:
1. Values of the relative hydraulic conductivity were increased at a rate of
about 1.03% per each unit of increase in soil salinity above EC 4 dSm”l.
2. Relative hydraulic conductivity values decreased with increasing soil
sodicity, but increased with increasing soil salinity.
3. Relative hydraulic conductivity values gradually decreased with increasing
the soil content of clay and the levels of soil sodicity as well, but tended to
increase with increasing soil salinity under the tested levels of ESP and
clay%.
4. The net combined effect due to soil salinity (EC), soil sodicity and clay
content on hydraulic conductivity (K) is expressed by the equation;
K = 7.12 + 0.0749 EC ~0.0165 ESP ~4.90 log clay (R = 0.874***)
B. Soil pH (in 1:2.5 soil:water suspension):
The following trends for soil pH under saline-sodic conditions were
obvious:
1. The soil pH negatively correlated with soil salinity, at a rate of about 0.04
pH unit reduction per each unit of increase in EC above 4 dSm”. The soil
sodicity increased the soil pH at a rate of about 0.03 pH unit versus each
ESP unit above 15.
2. Soil pH decreased, on average, (from 8.81 to 8.17) with increasing the clay
content of the soil from 2.32 up to 57.98%.
3. The combined effect of soil salinity, soil sodicity and clay content on soil
pH is described by the equation:
pH = 9.23 ~0.0462 EC + 0.0054 ESP - 0.0109 clay (R = 0.638***)
c. Elemental content of barley plant:
The following trends of elemental content of barley plants. under salinesodic
1. N, P and K contents decreased with increasing soil salinity under all the
ESP levels, while N-content at EC 16 and 20 dSm-\ increased. Na, Ca and
Mg contents increased as the soil salinity increased, but the rate of increase
in Ca and Mg was slight, under all the ESP levels.
2. Plant content ofN, P, K, Ca and Mg was adversely affected with increasing
soil sodicity, while Na-content was progressively increased under all the
levels of soil salinity.
3. N, K, Ca and Mg contents of plants were positively affected” while Na+%
was negatively affected as the soil content of clay increased. P~Vc>showed no
clear trend due to increasing the clay fraction content in soil.
D. Total elemental uptake by barley plants:
Results of total elemental uptake by barley plants grown on saline-sodic
soils reveal the following:
1. Uptake of N, P, K, Na, Ca and Mg by plants was significantly reduced as
the soil salinity increased at different levels of ESP.
2. Uptake of N, P, Kj Ca and Mg soundly decreased with increasing soil
sodicity, while Na-uptake was incraesed.
3. Uptake of N, P, K, Na, Ca and Mg significantly increased as the clay
content increased.
4. The combined effect of soil salinity, soil sodicity and the clay content of the
tested soil models on plant uptake ofN, P, K, Na, Ca and Mg is described
by the equations:
N-uptake = 64.40 - 4.30 EC + 0.1590 ESP + ~.02 clay
P-uptake = 18.00 - 1.10 EC + 0.0703 ESP + 0.186 clay
K-uptake = 69.70 - 4.29 EC + 0.2570 ESP + 1.06 clay
Na-uptake = 46.30 - 2.58 EC + 0.3040 ESP + 0.427 clay
Ca-uptake = 13.20 - 0.758 EC + 0.0908 ESP + 0.309 clay
Mg-uptake = 9.38 - 0.427 Ee + 0.0344 ESP + 0.200 clay
E- Dry matter yield (D.M.):
Results of the D.M. yield of barley plants grown on saline-sodic soil
models showed the following trends:
1. D.M. yield of tested soil models was decreased by about 0.12 g/pot for each
unit (Ee) of increase in soil salinity 2. D.M. yield decreased with increasing soil sodicity at different levels of soil
salinity, at a rate of 0.016 g/pot for each unit of increase in ESP above 20.
3. D.M. yield significantly increased with increasing the clay content, the rate
of the increase was about 0.03 glpot per each 1% of clay.
4. The net effect of soil salinity, soil sodicity and the clay content of the tested
soil models on D.M. yield is expressed by this equation:
D.M. yield = 2.45 - 0.144 Ee + 0.0137 ESP + 0.0295 clay (R:::; 0.952***)
Finally, it should be referreing that this investigation represent a
preliminary study only restricted to the conditions prevailing in soils of ”Delta”
in Egypt and barley (var. Giza 123) as an indicator plant. However, it could be
profitable for assessment the salt affected soils under other conditions and other
crops by developing specific new equations, in the same way that could be more
sutiable for such conditions.