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Soil water logging and salinity problems in a newly reclaimed area and the recommended solutions
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Abstract: In generally, the newly reclaimed lands in Egypt, especially those of a relatively coarse texture, are not provided with the drainage systems, as the groundwater levels are relatively low. Due to the continuing water conveyance through irrigation canals and bad water management in the studied area, ground water level tends to rise towards soil surface, consequently soil salinity and alkalinity problems, which will be a matter of course the main objective in this study. So, the current study was carried out to investigate and to determine the sources of the high water table and its effect on soil salinity and alkalinity problems and the recommended solutions at a newly reclaimed area, Wadi El-Shieh, southeast of Assiut city, Egypt.
Three soil units were selected (I, II and III) and surveyed as loamy sand to sandy clay loam (I), and sandy to loamy sand (II and III). The first soil unit (I) cultivated with grapes, while the second two units (II & III) cultivated with mango.
The results reveal that the total drainable pores (TDP) ranged between 21.3-23.6, 23.3-23.5 and 22.4-23.6 % for soil units I, II and III, respectively. The water table depths ranged between 0.46-1.40, 0.27-1.31 and 0.34-1.13 m below soil surface at soil units I, II and III, respectively. The ground water salinity varied between 1.35-33.0, 3.65-42 and 2.5-31.4 dS/m at soil units I, II and III, respectively. It is note worthy that salinity of groundwater increased with decreasing the water table depth.
It is noticed also that, although irrigation method was drip, the water losses was too much due to the excess dripper discharges (23 l/hour), in addition to leakage from irrigation line system (PVC) and seepage from open irrigation canal. These bad conditions resulted in high water table in about 40.0, 76.7 and 54.2 % of the soil samples of units I, II and III, respectively, as well as suffered from salinity problems. The corresponding ones were 44, 60 and 50 % for soil samples suffer from alkalinity problems, respectively.
Good correlation was found between ECe values and Na+ concentrations. The fitting curve for this relation showed a liner correlation, with correlation coefficients of 0.92, 0.82 and 0.89 at soil units I, II and III, respectively. Such relation is an important to give a quick prediction for the soluble sodium concentrations in the soils with a known soil salinity of saturated extract.
The measured actual crop water management for mango and grapes trees was 147.2 m3/fed/day, this value is too much. Maximum and minimum recommended crop water requirements during the first year for mango trees in June and February were 9.83 and 2.24 m3/fed/day, respectively, while for grape trees, they were (7.64 and 2.32 m3/fed/day) in June and November, respectively. The calculated leaching requirement for both mango and grapes were 1.7 % from the suggested crop water requirements. Using this quantity of irrigation water will reduce the losses of irrigation water.
The measured soil hydraulic conductivity (K) values ranged between 0.21 and 1.02 m/day, with an average 0.64 m/day for unit I; 0.71 and 1.08 m/day, with an average of 0.91 m/day for unit II and III, respectively. By digging deep hole up to 10 m below soil surface, no impermeable layer (D) was found. The equivalent depth (d) varied from 2.91 to 6.85 m.
The average calculated lateral spacing values at unit I varied from 32 to 100 m with an average of 69 m according to Hooghoudt’s formula and varied from 28 to 94 m with an average 67 m according to Toksoz-Kirkham formula. At units II and III, they varied from 80 to 100 m with an average of 90 m according to Hooghoudt and they varied from 77 to 99 m with an average 89 m according to Toksoz-Kirkham formula. Accordingly, the spacing were 70 and 90 m for units I and II & III, respectively. So, the high water table and soil salinity problems could be solved by applying a good drainage system and adequate water management
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| URL |
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| Publication year |
2006
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| Pages |
188-208
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| Organization Name |
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| City |
الزقازيق
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| serial title |
Egypt. J. of Appl. Sci
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| Author(s) from ARC |
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| Agris Categories |
DrainageNature conservation and land resources
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AGROVOC
TERMS |
Reclaimed land.
Salinity.
Subsurface drainage.
Water management.
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| Publication Type |
Journal
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