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

Abstract

This study is devoted to predict water vapour adsorption and hydro-physical properties of arid soils in middle Nile Delta (Farm of the Faculty of Agriculture, Shebin El-Kom, Egypt) and of tropical soils (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 (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 (Felix Farm) and clay loam soils (Shebin El-Kom Farm), and 3 rd & 4 th are clay soils (INIAP Farm). Data of soilwater adsorption (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 (Wa) were observed in the clay depths of 60-90 cm and 90-120 cm (INIAP-soil profiles) while the lowest values were in the subsurface depth (30-60 cm) of soil profiles 1 st and 2 nd. The other hygrophysical properties such as adsorbed layers and maximum hygroscopic water were obtained. The specific surface area (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 (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 (1) to predict P/Po at water adsorption capacity (Wa), and (2) to apply Wa in prediction of soil moisture retention i.e., ѱ(W) function at pF < 4.5.

Land-use change influence soil quality parameters at an ecologically fragile area of YongDeng County of Gansu Province, China

“…However, a certain amount of soil water facilitates the preservation of soil structure, which increases soil sorption, and increases nutrient uptake and soil solidity. The soil’s adsorption capacity increases nutrient absorption and stability, thereby increasing the soil’s organic carbon content ( Amer, 2019 ).…”

Peer Review #1 of "Land-use change influence soil quality parameters at an ecologically fragile area of YongDeng County of Gansu Province, China (v0.1)"

“…However, a certain amount of soil water facilitates the preservation of soil structure, which increases soil sorption, and increases nutrient uptake and soil solidity. The soil's adsorption capacity increases nutrient absorption and stability, thereby increasing the soil's organic carbon content (Amer, 2019). Thirdly, a positive correlation existed between soil electrical conductivity and total soil nitrogen, which could be explained by an increase in soil electrical conductivity and an increase in the rate of organic matter accumulation and mineralization by the soil (Ding et al, 2020).…”