Document Type : Research articles.
Authors
1
Soils, Water and Environ. Res. Inst., Agric. Res. Center, Giza, Egypt
2
Soils and Water Dept., Fac. of Agric., Fayoum University, Egypt
Abstract
The current study is of importance to support the local knowledge,
concerning the best use of land and available water resources whether be
under demand for agricultural utilization or be planned for later on use.
Also, it represents an environmental problem at a new industrial city of El
Asher min Ramadan area, i.e., the utilization of contaminated industrial
wastewater used as an irrigating source for an adjacent agricultural desert
area. In that concerning a hazardous that may cause toxic effects on both
crop products and human health. Consequently, it should be executed a
suitable soil amendment practices to minimize such possible adverse
effects. In this connection, two soil sites are of sandy loam and sandy clay
loam texture grades as well as 7 and 13 years land use periods in
agricultural utilization, respectively, and directly irrigated with
contaminated industrial wastewater after being passed through an
oxidation pond were undertaken in this study. These soils are
encompassing by the aeolian deposits, and classified as Typic
Torriorthents, coarse (soil site 1) or fine loamy (soil site 2), mixed,
thermic. According to a parametric evaluation system, they could be
evaluated as moderately (S2s1s3s4) and highly suitable (S1s1s3s4) for soil
sites 1 and 2, respectively, with an intensity degree for each of soil
texture, CaCO3 and gypsum as soil limitations lies in the range of slightmoderate (rating = 90-75).
An elemental composition analysis was executed on each of the
studied two soil sites, besides the industrial wastewater used for irrigating
them, and it was found that available contents of Fe, Mn, Zn, Cu, Pb, Cd
and Ni within the permissible limits, with one exception for Cd content
whose laid at the upper critical limit for soil site 1 and exceeded it in
soil site 2, since the soluble Cd content in the available irrigation water
source is more than the permissible limits. That means both the studied
irrigation water source and soils are Cd-polluted ones. Thus, Zn-soil
amendment was a matter of concern in this work due to support the
antagonism phenomenon between Cd and Zn through their uptake by
plant roots. Hence, a field experiment was conducted on the chosen two
soil sites, where wheat (Triticum astivum, c.v. Giza 163) and barley
(Hordeum vulgare, c.v. Giza 126) were sown during the winter season of
2005-2006. The investigated soil plots were irrigated with industrial
wastewater in randomized complete block design, with three replicates.
The agricultural management practices were conducted as usual. Zn was
applied to soil plots under study at three rates, i.e., 0, 5 and 10 kg Zn fed-1
in form of zinc sulphate (22 % Zn) as soil application.
The obtained results showed a beneficial effect of Zn, especially at a
high Cd level on the grown plants. Also, applied Zn caused more
pronounced increments in lengths or dry weights of shoots and the
biological yields of wheat and barley crops and their Zn contents at the
expense of Cd. The results revealed also that wheat was more sensitive to
both Zn-deficiency and Cd toxicity as compared to barley. Cadmium
toxicity in the shoots was alleviated by Zn application, but this was not
accompanied by corresponding decrease in shoot concentrations of Cd. In
addition, increasing Zn:Cd in the soils tended to decrease Cd
concentrations in plant organs. It could be deduced that Zn protected
plants from Cd toxicity by improving plant defense against Cd- toxicity
and its oxidative stress through competing with Cd for binding to critical
cell constituents such as enzymes and membrane protein and lipids
Keywords
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