الفهرس 
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Abstract
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TWo pot experiments were conducted in the greenhouse
of the Soils and Water Use Department. National Research
Center in 3 replicates to stUdy the effect of irrigation
methods: Subsurface irrigation (SSI). Surface irrigation
(51) and drip irrigation (DI). and mulches used: Control
(C). 50 9 bitumen/ma (B1). 100 g bitumen/ma (Ba). white
plastic sheet (WPS). black plastic sheet (BPS). 0.5 em
gravel layer (2.8-4.0 mm in diameter) (G1). and 1.5 cm
gravel layer (Ga) on: i) water balance. ii) plant
growth. iii) evapotranspiration and water use efficiency
(ET: WUE) and iv) Boil salinity and temperature. The pots
used were 20 cm in the inside di~eter and 20 cm deep.
Seven kgs of an air dried sandy soil «0.3 am in
diameter) were packed in each pot. In the 1st experiment.
the pots were irrigated to the soil field capacity and
left bore for evaporation process for 37 days. In the 2nd
experiment. the pot were planted with corn as an
indicator plant. They were irrigated twice a week to
raise soil moisture to the field capacity during 9 weeks.
Data obtained could be summarized in the follOWing:
_. _ .. __ .... _. ~--_. ---
94
According to the mulches used. the reduction in
water 1088 via evaporation varied 1.13-28.09. 4’.12-37.11.
and 1.12-30.34% relative to the control under SSl. SI.
and DI. respectively. Regardless of theirrigat ion
method. the following descending order represents the
relative effect of mulches treatments on reducing water
loss~’ Ga > WPS - BPS > G1 - Ba > ”control - B1.
Difference in water loss between any two non equal
mulches treatments was significant at the 5% level.
whereas that due to·’irrigation methods and/or to
irrigation methods x· mulches used was not. from water
conservation point of view in soil. the superiority of
plastic sheets and gravel mulches over ot·hertreatments
was not questionable under 51 and 01. respectively. On
the other hand. they were similar and the best under SSI.
Whereas the least effective ones were B1 and Ba in all
cases.
All mulches treatments increased germination per
cent and rate under SSI and D1. They increased plant
shoot weight under 51 and DI with the exception o~ Ba in
the last case. Although plant growth under SSl exceeded
that under both 51 and 01. a depressed effect ot mulching
was noticed. The effect of irrigation methods on
increasing shoots (fresh). shoots and roots (dry) weight
could be written in the following ascending order: 51 <
95
D1 < 551. Difference in plant weight between irrigtaion
methods was significant at the 5% level. except that
between 51 and Dl with respect to shoots fresh weight.
Concerriing the positive effect of mulches treatments on
shoots and roots dry weight. the result ended with the
following decreasing orders: G1 > WPS > Control - Ga >
BPS > B1 > Ba and 61 > Control > Ga > WP5 > B1 > BPS >
Ba respectively.
The effect of the interaction irrigation methods x
mulches used was significant at the 5% level in some
cases and non significant in others. 5SI was promising
for plant growth assuming that salt balance in root
medium could be controlled. The biggest shoots and roots
weight were obtained with 5SI and/or G1• regardless of
the mulches used and irrigation methods: respectively. An
inverse linear relationship significant at the 5% level
was found between the increase in soil temperature above
23.4°C at 5.0 em deep and shoots/roots ratio.
The reduction in ET relative to the control ranged
16.7-52.81. 27 .61-61.79 and 14.03-51.15% according to the
mulched used under SSI. 51. and 01. respectively.
Regardless of the mulches used ET could be stated in the
following descending order. Dl > SS1 = 51. Difference in
--~ ------~-
96
ET between 01 and both SSl and 51 was significant at the
5% level. The following ascending order describes the
relative effect of the mulches used on reducing ET
regardless of irrigation methods : Control < G1 < B1 < Ba
< WPS < BPS < Ga. Differ~nce between treatments was
significant at the 5% level except that between any two
treatments of (61. B1; Ba) and of (WPS. BPS) Ga}.
According to the mulches used. the increase in WOE
relative to the control varied 4.0-33.2. 126.6-402.1. an~
24.3-311.0% under 551. 51 and 01. respectively. The WUE
on the SSI exceeded that on 51 and 01. and the
difference was significant at the ~% level. The following
descending order expresses the positive effect of
mulching on WUE Ga ~ BPS”> WP5 > 61 ) Ba ) B~ > Control.
Difference between treatments was significant at the 5%
level except that between the equal ones in the-order.
The effect of the interaction irrigation methods x
mulches used on both ET and WOE was significant at the 5%
level in some cases.
Mulching the soil decreased the salinity in the
upper layer relative to the control. Exception to that
was found with’(B1. Ba. WPS; BPS) and (81) treatments
under 51 and 01. respectively. The biggest reduction
97
occurred with G~ and Ga. According to the mulch used the
reduction varied 26.2-61.5. 8.6-22.4. dnd 20.5-38.6%
relative to control under 881. 81 and Dl. respectively.
The effect of irrigation methods and/or mulches used in
increasing salinity could be written in the following
descending order: S51 > 51 > 01. and B1 > Ba > Control )
WPS > BPS > G~ > Ga. Difference between irrigation
treatments was significant at the 5% level.
The effect of irrigation methods and/or mulches used
on increasing salinity could be summarized in the
following descending orders: (01 = 81 ) 551) and (Ga >
BPS > WPS > Ba > G~ - control > B1>’ (51 > Dl > 551) and
(control > BPS - Ga - WPS > Ba > Gs. - B~) in the medium
and lower layer. respectively. The ability of S51 : 91 :
Dl on soil salinization without mulching could be
expres5ed by the following ratios: 4.7: 1.0 : 1.4. 1.0
: 1.5 ; 1.3. and 1.0 : 3.7 ; 4.2 in the upper. medium
and lower soil layer. respectively. Soil mulching
decreased the salinity of the lower layer under 51 and
Dl. The effect of irrigation methods x mulches used on
the salinity of the upper layer was significant at the 5%
between some treatments.
98
The increase in soil temperature at 5 em depth
ranged 1.0-2.0. 0.8-1.7. and O.2-1.2°C at 10 A.M .• and
5.2-6.2. 1.1-2.2. and O.4-1.6°C at 2.30 P.M .• under 551.
51 and DI. respectively. The minimum and maximum increase
in soil temperature were achieved with (B1’ G~) and B1’
WPS) under both sst and 51. and DI. respectively.