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العنوان
Effect of saline water on some physical and chemical soil properties /
المؤلف
Rahoma, A. D. K.
هيئة الاعداد
باحث / .D.K. rahoma
مشرف / S.A. Ibrahim
مناقش / m.e.a.ali
مناقش / o.h.m.el-hosainy
الموضوع
Soil. Soil chemistry. Soil physics.
تاريخ النشر
1999.
عدد الصفحات
91 p. :
اللغة
الإنجليزية
الدرجة
ماجستير
التخصص
الزراعية والعلوم البيولوجية (المتنوعة)
تاريخ الإجازة
1/1/1999
مكان الإجازة
جامعة بنها - كلية الزراعة - اراضى
الفهرس
Only 14 pages are availabe for public view

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Abstract

This study aims to investigate the effect of using saline irrigation
water of different qualities on the main physical and chemical properties of
soils. The area of study was located at the north of Edko lake, EI-Behera
governorate. This area included three types of irrigation water namely, EIMahodeia
canal fresh water, uEC ~ 0.59 dSm-1(G1)” drainage water of EC
3.03 dSm-1 (G4) and two mixtures of both water types, having mixing ratios
of 2:1 and 1:2 fresh to drainage water, EC values of these mixtures were
1.63 dSm-1(G2) and 1.99 dSm-1 (G3). This study was represented by 13 soil
profiles.
”Disturbed and undisturbed samples were taken from each layer (0-
30, 30-60, 60-90 cm) of each soil profile to determine the chemical and
physical properties Le. electrical conductivity soil reaction, organic matter,
soluble cations and anions, exchangeable cations, total carbonate,
particle size distribution, water stable aggregate, pore size distribution total
porosity, saturated hydraulic conductiVity and bulk density.
The obtained results revealed the following:
The canal fresh water (G1) was free of residual sodium carbonate,
having EC of 0.59 dSm-1 and SAR of 1.21 and so was classified according
to USS Salinity Laboratory Staff (1954) as C2S1. The other three grades of
irrigation water also free of residual sodium carbonate and classified as
C3S1 • C352 and C.•52 or C.•S3, respectively.
The decreasing order of soluble cations of the fresh water was
Mg++ > Na+> Ca++ while in the drainage water the order was Na+> Mg++>
Ca++.
The distribution of soluble anions in the fresh water was in the order
of HC03-> S04= > cr, whereas Clwas the dominant all the other types of
irrigation water; followed by HC03- and then S04= soluble anion.
The pH values of the soil under consideration were not markedly
affected by water irrigation of different qualities.
Increasing of irrigation water salinity (ECwI) from 0.59 dSm-1 (G1) to
3.05 dsm” (G4) increased the soil salinity from 2.22 dSm-1 as high as 12.70
dSm-1 for G1 and G4 respectively.
Results showed that the soluble sodium of the studied soil profile
was the dominant soluble cations followed by Mg++, Ca++ and t< and
tended to increase with increasing of drainage water ratio, while the
distribution of soluble anions showed that the soluble chloride was the
dominant soluble anion followed by sulphate, while the soluble
bicarbonate was approximately constant.
Exchangeable calcium tended to be gradually decreased with
increasing of drainage water ratio.
Since the exchangeable calcium values amounted to a range of
16.03-23.35 me/100 g soil in the soil irrigated with fresh water, this level
was dropped to a range of 4.24-13.51 me/100 g soil with drainage water
irrigation. The irrigation water mixture yielded values in between these two
extremes. Such results may attract attention to the probable hazard due to
long period irrigation with low water quality where Na+ replace Ca”
gradUally on the exchangeable sites of the clay complex.
The texture class of soils profile under study is clay with clay
percent of about 55-74 as a mean values.
The organic matter content was generally low and ranged between
0.68% and 2.13%, and decreased with depth. Also, carbonate content was
generally low (*1.09 % and 2.98%) as a mean values.
With increasing of total soluble salts (EC values) from 2.22 dsm’
(G1) to 4.54 dSm-1 (G2), the aggregate state was decreased to the lowest
mean values of 46.08. However with increasing of EC values from 4.5
dSm-1 (G2) to 12.7 dSm-1 (G4) the aggregate state is again improved and
reached to its maximum value 52.91 in the highest saline soil (G4).
The quickly drainable pores, slowly drainable pores and water
holding pores were proportionally related to exchangeable calcium
inversely to EC, ESP and exchangeable magnesium, while an opposite
trend was exhibited with fine capillary pores. On the other hand the
increasing of EC, ESP and also exchangeable magnesium level act as
dispersing agent lead to encourage the abundance of micro on the
expense of macro pores.
As the soil total soluble salts, exchangeable sodium and
exchangeable magnesium increased the upper limits of both filed capacity
and wilting point were also increased. However, effect of the Ee, ESP as
well as exchangeable magnesium were more effective in raising the upper
limit of the wilting point level rather than that of the field capacity, as a
consequence the available water content was reversely related to these
parameters. The exchangeable calcium lowers the upper limits of both filed
capacity and wilting point but its effected on lowering the upper limit of
wilting point is more- pronounced, hence an increase of available water is
achieved with increasing of exchangeable calcium.
The saturated hydraulic conductivity (K) values were generally very
low, that may be due to the dominancy of the clay fraction in the tested
soils.
The general mean values of hydraulic conductivity were parallel with
general mean values of aggregate state and mean weight diameter.
from the previous results and with respect to EC and ESP it is
evident that the soil were deteriorated by usinq the bad quality of irrigation,
since the soil were changed from normal to saline and then to saline sodic
soil.
A successful irrigated agriculture requires permanent control of
salinity and irrigation water. Reclamation of affected soil by means of
improved drainage, chemical treatments and leaching of salts can reduce
natural hazard.
Gypsum is the most commonly used amendments for reclaiming
sodium-affected soil and reducing the harmful effects of high sodium
irrigation water. Gypsum added to sodic soil increases permeability by
increasing electrolyte concentration and by reducing exchangeable
sodium.
Finally the obtained results may attract the attention to the hazard
predicted upon irrigating the soils with low quality waters particularly for
long periods and in absence of effective drainage systems.