Soil gel-conditioner : II. effect of treated upper layer depth on infiltrability of sandy soil under sprinkler infiltration

الملخص EN

The objective of this study was to investigate the effect of adding Aquasorb gel-conditioner to the upper treated layer on the vertical movement of the water in sandy soil columns (Typic Torripsamments) under sprinkler infiltration.

The Aquasorb gel particles were highly swollen upon water absorption resulted in large surface expansion.

The value of the absolute expansion was not influenced by water application rate (R), but was linearly increased with increasing concentrations (C) and treated soil layer depth (dt).

However, the relative expansion was exponentially diminished with increasing wetting front advance (L) and it was dependent on both C and dt, but was not influenced by R.

The surface expansion occurred gradually during infiltration and most of the expansion (> 70%) had occurred when the wetting front reached 30 cm below the initial soil surface.

The rate of wetting front advance (dL/dt) reduced by either increasing C or dt and it increased by decreasing R.

The resulted bulk density (Db) distribution profiles was an entity of the Aquasorb conditioner and was not affected by R but rather by C and dt.

The Db at the upper 5 and 10 cm depths were significantly reduced by increasing dt from 5 to 10 cm depth which after no significant differences were evident, whereas, the average Db at the upper 20 cm depth continued to decrease significantly with increasing dt.

The water distribution profiles were positively influenced by R, C and dt.

The average water content (θ) at the upper 5, 10 and 20 cm depths increased exponentially with increasing R, C and dt.

However, the average θ at the upper 5, 10 or 20 cm depths were significantly in creased by increasing dt from 5 to 10 cm depth, which after no significant differences were evident.

It can be concluded from this study that the optimum C for a stratified sandy soil profile is 0.4 %, and the optimum dt is 10 cm, which conjugated with any convenient R under sprinkler (rain) infiltration.