Vol. 35 – 2009 - Ecologia Mediterranea - Université d'Avignon et des ...
Vol. 35 – 2009 - Ecologia Mediterranea - Université d'Avignon et des ...
Vol. 35 – 2009 - Ecologia Mediterranea - Université d'Avignon et des ...
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Materials and m<strong>et</strong>hods<br />
Choice of the study area<br />
The Ouargla commune which is located at the<br />
center of the Ouargla basin was chosen<br />
because this site takes into account importance<br />
of its date palm crop heritage (DPAT<br />
2001) and, abandonment and d<strong>et</strong>erioration of<br />
several of its palm plantations caused by the<br />
effects of groundwater rise on growth of the<br />
date palm.<br />
Date palm areas are chosen from five areas<br />
which all are agrarian ecosystems: namely<br />
Bamendil, Mekhadma, Ksar, Said Otba and<br />
Beni Thour. Our investigation dealt with 167<br />
palm plantations b<strong>et</strong>ween 15 and 45 years old<br />
(Figure 1). The whole of these areas forms<br />
97% of the total surface, occupied by date<br />
palm crops in Ouargla district (DSAO 2001).<br />
Hydro-edaphic study<br />
Our m<strong>et</strong>hodological approach consisted of<br />
measuring the param<strong>et</strong>ers of the degradation:<br />
groundwater levels and salinity, crusts levels,<br />
irrigation water and soils salinity.<br />
Figure 1 <strong>–</strong> The date palm areas in the Ouargla basin.<br />
ecologia mediterranea <strong>–</strong> <strong>Vol</strong>. <strong>35</strong> <strong>–</strong> <strong>2009</strong><br />
Effects of hydro-edaphic environment on the rooting of date palm (Phoenix dactylifera L.) Degl<strong>et</strong> Noor<br />
in the Ouargla Basin (south-east algeria)<br />
Study was carried out during winter period<br />
(2002) when groundwater level reaches its<br />
maximum. We measured water table depth<br />
(W.t.d.) compared to soil surface using an<br />
electric probe, and we collected water to measure<br />
electric conductivity of water table<br />
(E.C. w.t. ) at 25 o C with a conductivim<strong>et</strong>er.<br />
Groundwaters were classified in 4 water table<br />
groups, ranging b<strong>et</strong>ween 0-40 cm, 40-80 cm,<br />
80-120 cm and higher than 120 cm of depth.<br />
The gypseous crusts depths (G.c.d.) were<br />
d<strong>et</strong>ermined by a gradual survey. Nature of the<br />
crusts is given following maps and soils toposequencies<br />
of the Ouargla basin (Hamdi Aïssa<br />
2001), and confirmed by fast tests at the laboratory.<br />
First, the test of effervescence with<br />
HCl enabled us to d<strong>et</strong>ermine presence of<br />
limestone, and secondly, the test of precipitation<br />
of sulphates by BaCl 2 enabled us to d<strong>et</strong>ermine<br />
presence of gypsum (Aubert 1978). We<br />
also measured the electric conductivity of irrigation<br />
water (E.C. i.w. ), and soils salinity at 0-<br />
40 cm depth level. The samplings of soil were<br />
carried out with an auger and the measurement<br />
of electric conductivity of soil-water<br />
extract 1:5 (E.C. e1:5 ), at 25 o C.<br />
43