Soil moisture adsorption capacity and specific surface area in relation to water vapor pressure in arid and tropical soils

Authors : Abdelmonem Mohamed AMER

Pages : 289-297

Doi:10.18393/ejss.580889

View : 70 | Download : 6

Publication Date : 2019-10-01

Article Type : Research Paper

Abstract :This study is devoted to predict water vapour adsorption and hydro-physical properties of arid soils in middle Nile Delta insert ignore into journalissuearticles values(Farm of the Faculty of Agriculture, Shebin El-Kom, Egypt); and of tropical soils insert ignore into journalissuearticles values( Felix and INIAP Farms); in Quevedo zone, Los Rios, Ecuador. The vapour pressure and isothermal adsorption of water vapour is used to predict soil moisture adsorption capacity insert ignore into journalissuearticles values( Wa ); and the specific surface area. To achieve these objectives, four soil profiles at different depths were investigated to indicate the status of hydro-physical properties of the studied area.  The 1 st & 2 nd profiles are sandy loam insert ignore into journalissuearticles values( Felix Farm ); and clay loam soils insert ignore into journalissuearticles values( Shebin El-Kom Farm );, and 3 rd & 4 th are clay soils insert ignore into journalissuearticles values( INIAP Farm); . Data of soil-water adsorption insert ignore into journalissuearticles values(W%); at different relative vapor pressures P/Po are obtained for the studied soil profiles, where the W% values increased with increasing P/Po from 1.87% to 10.01% in the 1 st and 2 nd sandy loam and clay loam soil profiles, and reached 27.44% in the 4 th clay soil profile. The highest values of water adsorption capacity insert ignore into journalissuearticles values( Wa ); were observed in the clay depths of 60 – 90 cm and 90 – 120 cm insert ignore into journalissuearticles values(INIAP-soil profiles); while the lowest values were in the subsurface depth insert ignore into journalissuearticles values(30 – 60 cm); of soil profiles 1 st and 2 nd . T he other hygro-physical properties such as adsorbed layers and maximum hygroscopic water were obtained. The specific surface area insert ignore into journalissuearticles values( S ); in sandy loam 1 st &2 nd soil profiles is ranged from 113m 2 /g to 187m 2 /g and raised to 385m 2 /g and 553m 2 /g in the 3 rd & 4 th clay soil profiles. The corresponded values of the external specific surface area insert ignore into journalissuearticles values( Se ); ranged from 42m 2 /g to 98m 2 /g and 74 m 2 /g to 252 m 2 /g respectively. Two equations were assumed insert ignore into journalissuearticles values(1); to predict P/Po at water adsorption capacity insert ignore into journalissuearticles values( Wa );, and insert ignore into journalissuearticles values(2); to apply Wa in prediction of soil moisture retention i.e., ѱinsert ignore into journalissuearticles values(W); function at pF < 4.5.
Keywords : Water adsorption capacity, vapor pressure isotherm, soil hydro physical properties, specific surface area, arid and tropical soils

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