الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Two laboratory experiments (columns and vapor pressure experiment) were carried out during 2010-2011, at the laboratory of Soils Dept., Fac. Agric., Mansoura Univ., Egypt, to study the water potential and movement of salts and some nutrients in an alluvial loamy soil. Five factors were studied in columns experiment as follow: water flow (vertical and horizontal), soil water potential (SP and FC), salts type (0, NaCl and Na2SO4), N-fertilizer rates (0, 120 and 180 kg N fed-1) and depths (10, 20 and 30 cm). While, in vapor pressure, it used two factors salts type and N-fertilizer rates.
The vapor pressure results proved that the most effective treatment in increasing the maximum hygroscopic water in sorption curves and decreased the desorbed water in desorption curves was sodium chloride then sodium sulfate with the high rate of ammonium sulfate fertilizer at relative humidity 93%. Also, this treatment decreased some physical properties (pore size distribution, mean pore diameter, hydraulic conductivity and intrinsic permeability). Additionally, columns data confirmed the previous results, wherein sodium chloride increases soil water holding capacity, EC (dS m-1) and Na+&Cl- concentration. Also, soil water flow decreased with increasing soil salinity (by sodium chloride) especially at vertical water flow. This effect consequently increases the solutes flux jc (g m-2 h-1) and accumulation. These results might be due to the decreasing of the average apparent velocity (m h-1) of Na+ and Cl-.
Finally, these results illustrated that the structural degradation of an alluvial loamy soil is a function of both salinity [i.e. electrolyte concentration and risk ions (Na+, Cl- and SO4-2)] and sodicity of the sodium salts. Consequently, there is an increase the osmotic potential (decrease energy of soil water) and resulted in a decrease of water and nutrients availability for plants. So these fertilizers or saline water compete the plants on water. Also, continuing use of salts source will increase this effect by time. The greatest nitrogen losses appeared under saturated conditions through a process of volatilization and denitrification.
Therefore, it must be deduce possible methodologies for determining the electrolyte beginning in soils and maintain the moisture level required to activate the diffusion process and horizontal water flow at an alluvial loamy soil to avoid the problems of increasing the soil water potential.