Vol. 35 – 2009 - Ecologia Mediterranea - Université d'Avignon et des ...

excessively salted to very excessively salted.
Electric conductivity of water varied from 10
to 39.7 dS.m -1 . Among all studied waters,
37.8% were excessively salted, higher than 20
dS.m -1 . Compared to literature (USSL 1954;
Durand 1958), groundwater of Mekhadma
was the less charged with salts. However,
conductivity measurements showed that
groundwater of Said Otba and Ksar were the
less salted.
The chemical facies of water tables and soil
solutions in the Ouargla basin varied between
sulphated calcic, sulphated magnesian-sodic
and chlorinated sodic (Hamdi Aïssa 2001).
The gypseous crusts depths varied from 33.3
to 117 cm. They were gypseous in Bamendil
and Mékhadma, and gypseous calcareous in
Ksar and Beni Thour.
The soils salinity increased with the level of
groundwaters, it lied between 1.1 and 5.8
dS.m -1 for the soils of deep water table, higher
than 1.2 m of depth, and between 2.1 to 9.8
dS.m -1 for the soils of shallow water table.
The gypseous crusts create in the soils of deep
water table an obstacle for the infiltration of
salted irrigation water, which increases the
capillary rise of water and thus the salts accumulation
on the soils surface. However, the
average salinity in the soils of shallow water
table showed that the salinity of soils without
crust is higher than that of the soils with
crusts. The absence of crust decreased the
effect of saline irrigation water and increased
significantly the salts accumulation in the
soils surface with the capillary rise of saline
water tables. The decrease of water tables
depth contributed significantly to increase
soil’s salinity.
Date palms rooting study
56.9% of the palm plantations exhibited a rooting
depth between 27 and 119 cm (Figure 3).
The shallow water table and the crust formed
hydrous and mechanic shallow obstacles for
date palms rooting. The study of date palm
areas revealed that 43.1% of the palm plantations
presented shallow water table obstacles,
10.8% shallow water tables and crusts, 3%
shallow crusts and 43.1% were without shallow
obstacle. According to remote sensing
and field work by Hamdi Aïssa (2001), the
Ouargla basin is made (upstream to downstream)
by a sequence of five soil landscapes:
gypseous calcareous on the plateau; alluvioeolian
and regosolic on the slope; gypseous,
ecologia mediterranea – Vol. 35 – 2009
Effects of hydro-edaphic environment on the rooting of date palm (Phoenix dactylifera L.) Deglet Noor
in the Ouargla Basin (south-east algeria)
Figure 2 – Water table depths in the Ouargla date palm plantations.
Figure 3 – Depth of Deglet Noor date palm rooting
in the date crop areas of Ouargla.
with two subsystems (with a gypseous crust
of surface and gypseous-salted) on the chott;
and salted in the sebkha. The gypseous horizons
constitute the major characteristic of
these soil landscapes.
Impact of crusts in areas
of deep water tables
The results showed that 3% of the palm plantations,
with a rooting depth above 120 cm
were undergoing an obstacle of gypseous
crust at Bamendil and gypseous calcareous
crust, at Ksar and Beni Thour. This latter
constituted a physical obstacle for the rooting
of the date palm. There were positive correlations
(Figure 4), highly significant between
root depth of the date palm (R.d.) and gypseous
crusts depth (G.c.d.). We obtained the
following relation with R 2 = 0.9961: R.d. =
1.0099 G.c.d. – 0.2685.
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