Influence of a gel‐forming conditioner on water retention, infiltration capacity, and water distribution in uniform and stratified sandy soils

Abstract

The effect of an organic super-gel conditioner (Jalma) on water retention, saturated hydraulic conductivity (K s ), wetting front advance, infiltration rate, and water distribution profiles in uniform and stratified soil columns was investigated. The stratified soil column consisted of two layers: a Jalma-treated upper layer (10 cm depth) overlaid an untreated lower layer extending to 70 cm depth. Five concentrations of Jalma (J) were used: 0, 0.25, 0.50, 0.75, and 1% (on a dry weight basis). The amount of water retained by the soil at each matric potential over the range of -1 to-15,000 cm significantly increased with increase of J. The water retention curves were fitted by using Van Genuchten's model (r > .983). A sharp decrease in K s was obtained with increase of J, and the relationship was exponential (r = .999). Addition of Jalma to sandy soil created a saturation zone (5 cm depth) and a transition zone (from 5 to 10 cm depth) under ponded infiltration either in uniform or stratified profiles. The wetting front advance (Z) and cumulative infiltration (i) substantially decreased with increase of J. A simplified approach based upon Darcy's law along with the pertinent physical properties of resulting transmission zone was applied to the uniform as well as stratified profiles to compute Z and i. A good agreement was found between the computed and observed Z and i (r > .998). Addition of Jalma caused a decrease in the matric potential of wetting front (S w ). The values of S w in stratified profiles were higher than the corresponding values in uniform profiles. The initial water deficit of transmission zone (D i ) increased in the uniform profile but decreased in the stratified profile with increase of J. When Jalmatreated soil overlay untreated soil, the water content in the untreated soil (lower layer) was consistently lower than the water content at the corresponding depth in a uniform profile of the untreated soil. In general, it is suggested to add Jalma conditioner to the upper sandy layer (10 cm depth) at concentrations ranging from 0.6 to 0.8% for the best water conservation and plant benefit. However, the desired depth of wetting is considered an important factor in selection of an appropriate J.

Influence of upper layer treatment of gel‐forming conditioner on water movement in sandy soils under sprinkler infiltration

“…4) with those obtained under ponded infiltration. Al-Darby et al (1992) found that the water content in the lower layer of sandy soil pronouncedly decreased with increase of J in the upper layer. They showed that when the Jalma-treated soil overlay the untreated soil, the water contents in the untreated soil (lower layer) were consistently less than that of the corresponding depths in a uniform profile of the untreated soil, under ponded infiltration.…”

“…This means that under sprinkler infiltration, the soil surface can transmit the water downward before getting saturated. Al-Darby et al (1992) found that the water content at the surface in a stratified profile was identical to 0 S under ponded infiltration where a head of water was standing on soil surface. However, the value of 0 in the treated layer (Fig.…”

“…The superabsorbents can increase water supply to growing plants and improve water use efficiency , Terry and Nelson 1986. The addition of Jalma gel conditioner significantly increased the water retention of sandy soils , Al-Darby et al 1992. However, very little research has been conducted on the influence of soil surface treatment of gel conditioners on vertical water movement under sprinkler (rain) infiltration.…”

“…6-8 that the rate of advance of the wetting front is O.I O.I O.2 O.3 0.4 WATER CONTENT (e) ( Cm 3Hydraulic conductivity as a function of water content for untreated sandy soil. The relationship is taken from a determination byAl-Darby et al (1992).…”

Control of flow through porous media using polymer gels

“…Polymer gels are widely used for blocking water in oil and gas wells. [2][3][4] Gels may also be used to exclude water, e.g., to protect archeological sites from erosion due to rain or ground water leaching. 2 With increasing scarcity of potable water, gels may help preserving this valuable resource in arid soils.…”