Influence of a Highly Swelling Gel-forming Conditioner (Acryhope) on Hydrophysical Properties of Layered Sandy Soils.

Abstract

A laboratory column study was conducted on a layered sandy soil to investigate the effect of a cross-linked polyacrylate gel-forming conditioner Acryhope) on water retention and flow. Five concentrations (C) of Acryhope ranged from 0 to 1% (on dry weight basis) were applied to the upper layer (10 cm depth) as dry grains. The conditioner-gel particles were highly swollen upon water absorption resulted in large soil expansion. The resulted soil bulk densities were evaluated and used to obtain the water content by volume ().The increase in height of the surface was also measured. The amount of water retained by the soil at two suctions 10 and 1500 kPa increased exponentially with increase of C (r= 0.999). Increasing C at the upper treated layer substantially decreased the rate of wetting front advance through the profile and increased  in the upper 20 cm depth under ponded infiltration. Although the relative expansion (Lr) had increased with increase of C at upper layer, the value of Lr for each C remained approximately constant during ponded infiltration and a logarithmic relationship between Lr and C was found (r =0.972). Evaporation losses was effectively reduced with increase of C applied to the upper layer. Increasing C at the upper-treated layer substantially lowered the rate of capillary rise and increased the water content at this layer. The average water content at the upper layer (u) was exponentially related to C (r =0.992). In general, the effects of Acryhope were more pronounced when C at the upper treated layer (10 cm) of sandy soil ranged from 0.75 to 1%. However, it may be recommended to apply Acryhope conditioner to the upper layer of sandy soil and adjacent to the plant at concentration ranging from 0.5-0.75% for cost-benefit considerations.