Water flow and conductivity into capillary and non-capillary pores of soils

Abstract

Downward water flow in the vadose zone occurs principally through the non-capillary pores, while the redistribution and lateral and upward flow occurs in the capillary pores. The purpose of this study was to propose equations to estimate water flow, Q(θ), and hydraulic conductivity, K(θ), in the capillary and non-capillary soil pores. The equations related K(θ) to soil pore radius (r) were based on soil hydraulic data, including water retention h(q), field basic infiltration rate, water sorptivity (S) and distribution density function f(r) of the soil pore size. Calcareous sandy loam and alluvial clay soils located at the Nile Delta were used to test the validity of the assumed equations. Data showed that the values of K(θ) calculated by the proposed equations were in the common ranges for such soils. The equations are therefore expected to be applicable for both coarse and fine textured soils. Also, an equation was derived to estimate the sorptivity at steady state infiltration. It was observed that S is decreased in going from the un-saturation condition to steady state infiltration by 15.1% and 45.9% in sandy loam and clay soils, respectively.

Implication of Gypsum Rates to Optimize Hydraulic Conductivity for Variable‐Texture Saline–Sodic Soils Reclamation

“…On an average, the K s of LS remained the highest (13·08 cm day −1 ), followed by SL (1·63 cm day −1 ) and CL (1·05 cm day −1 ) soils perhaps because of the difference in soil texture; hence, it showed a negative correlation ( r = −0·69) with clay contents (Table ). Previously it was also shown that Na + ‐dominated course‐texture soils exhibited more K s compared with fine‐texture soils on behalf of macro‐pores (Frenkel et al, ; Ahuja et al, ; Lebron et al, ; Amer, ). A strong positive correlation of BD with sand (0·91) and a negative correlation with clay (−0·63) and silt (−0·73) content of soils have been observed under normal soil conditions (Chaudhari et al, ).…”

Procesos físicos del suelo en la reserva ecológica del Pedregal de San Ángel de Ciudad Universitaria: atributos para su conservación.

“…El porcentaje de arena varió signif icativamente desde 57.9 ± 0.26% en los sitios PAP hasta un 50.0 ± 0.04% en el suelo acumulado en las grietas (Cuadro 2). Los resultados del porcentaje de arena encontrados en los sitios PAC favorecerían la colonización de hierbas al ser sitios con alta capacidad de f iltración, mientras que los valores de limo y arcilla de los sitios abruptos (Gr y Ho) favorece el desarrollo de árboles y arbustos, pues estás partículas generan microporos que retienen agua capilar y generan humedad ambiental (Amer, 2012 et al (2000), la arena del suelo de la REPSA-CU está dentro del intervalo correspondiente a muy f inas (0.5 a 0.1 mm), en tanto que el limo es grueso (0.002 a 0.49 mm). Estos datos son congruentes con los que reportó Castellanos-Vargas (2001) 1 , donde encontró tamaños de arena (f ina a muy f ina) entre 0.07 a 0.2 mm de diámetro y limo de gruesos a medios entre 0.03 a 0.006 mm y son altamente preferidos por los ortópteros para ovipositar.…”

“…Secuestro de partículas y banco de latencia. La porosidad del suelo de los sitios de la REPSA-CU (Cuadro 2) puede incrementar las probabilidades de secuestrar las partículas atmosféricas suspendidas cuando interactúan con las moléculas de agua de lluvia, mediante su incorporación al espacio intersticial que existe entre los agregados edáf icos (Glasbey et al, 1991;Certini y Scalenghe, 2006;Paul, 2007;Amer, 2012). La baja densidad y la alta porosidad del suelo de la REPSA-CU se pueden considerar como factores que facilitan el resguardo de semillas en latencia.…”

Hydraulic conductivity and sorptivity at unsaturated and saturated conditions as related to water infiltration in soils

“…The soil hydraulic properties in relation to water infiltration are essential for quantifying the rate of water flow and transport processes in the plant root zone. Water flows in the root zone occur principally through the macro non-capillary pores of soil, while the redistribution and upward flow occur in the capillary soil matrix pores (Amer, 2012). The water conductivity of soil pores is mainly controlled by pore sizes, continuity and pore size distribution in soil.…”