A laboratory sprinkler (rain) infiltration experiment was carried out on long stratified columns of sandy soil (Typic Torripsamments) packed to 1.50 g cm -3 bulk density to investigate the effect of gel-forming conditioner (Jalma) on wetting front advance Z, water distribution, and redistribution profiles under different sprinkler intensities I using a simple sprinkler simulator. Five concentrations of Jalma J, 0.0, 0.25, 0.50, 0.75, and 1.0% (on dry weight basis), were uniformly applied to the upper layer (10-cm depth) at three sprinkler intensities of 1.25, 2.25, and 3.25 cm h -1 . The time required for the wetting front to reach 10-cm depth t° was significantly increased either by increasing J added to the upper layer or decreasing I applied on soil surface. However, the treatment of 1% J caused surface ponding before Z had advanced to 10-cm depth for the three values of I. A fairly uniform water profile was produced in the homogeneous soil (J = 0%), and the constant water content as fractional volume θ T was found equal to the ratio of the sprinkler intensity I to the velocity of the wetting front v. Addition of Jalma to the upper layer increased the water content in that layer, which was magnified by increasing I, but did not affect the value of θ T in the untreated lower layer. The higher water content observed at the soil surface due to Jalma application never approached the corresponding value of the saturation water content θ s under sprinkler infiltration. The experimental results revealed that the water movement in the untreated lower layer was unaffected by Jalma applied to the treated upper layer. Equations based on Darcy's law along with the physical properties of the resulted water distribution profile were derived to compute Z and θ T under sprinkler infiltration as affected by Jalma applied to the upper layer of sandy soil. The development of water redistribution profiles indicated that the amount of water retained in the treated upper layer was much higher than that in the untreated upper and lower layers at the same corresponding redistribution times and sprinkler intensity. However, the same uniform water content θ T , which was associated with -10 kPa matric potential on average, was approximately achieved in the untreated lower layer 3 days after sprinkler infiltration regardless of Jalma applied to the treated upper layer. In Address correspondence to A. M. Al-Omran. 217218 Y. Z. El-Shafei et al. general, the study may suggest application of Jalma conditioner at 0.75% to the upper layer (10-cm depth) of sandy soil under medium sprinkler intensity I around 2 cm h -1 and a wetted depth not more than 20 cm for the benefit of water use efficiency.

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.

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