Gel-conditioned barriers for water management of sandy soils

A laboratory study was conducted to investigate the effect of gel-forming conditioner (Jalma) at rates of 0.0, 0.2, 0.4 and 0.8% at four depths of gel-conditioned barriers: 0-0.05, 0.10-0.15, 0.15-0.20 and 0.20-0.25 m, on infiltration, intermittent evaporation, water conservation and soil moisture distribution for calcareous sandy soil (Typic Torripsamments) at two moisture regimes. Addition of 0.8% Jalma on surface significantly increased the time required for 50 mm to infiltrate ( t 5 0 ) into the soil. However, with deeper subsurface barriers the rate of Jalma application had no significant affect on t 5 0 for the first cycle. Time required for 50 mm to infiltrate for any Jalma rate increased with the number of irrigation cycles due to cumulative increase of moisture of soil columns. The times required for 100 mm to infiltrate ( t 1 0 0 ) increased with increased rate of Jalma application and decreased with the depth of the treated barrier. Surface treatment significantly reduced cumulative evaporation and thus increased the amount of water conserved (PWC). Subsurface Jalma-treated barriers promoted evaporation and hence reduced the amount of water conserved. Soil moisture profile of the columns showed that Jalma-treated barriers may be used to establish zones of maximum water storage at various depths in a sand profile.Soil Science department, College of Agriculture, King Saud University, P.O. Box 2460, Riyadh-11451, Saudi Arabi