Effects of Some Organic and Mineral Soil Amendments on Temporal Variability of Dynamic and Static Water Repellency in a Calcareous Soil

Water repellency (WR) of various degrees reported for different soil textures, land use, and climate conditions may decrease infiltration and increase runoff and soil erosion. WR can be influenced by soil amendments and may vary over time. In the present study, a completely randomized design experiment with three replications was conducted to evaluate the effect of soil amendments on dynamic and static WR in a calcareous soil. Treatments consisted of two organic (polyvinyl acetate, PVA and polyacrylamide, PAM at 4 levels of 0, 0.05, 0.1 and 0.2 g kg-1 soil) and two mineral amendments (pumice and perlite at 4 levels of 0, 0.5, 1 and 2 g kg-1 soil). Dynamic (water drop penetration time) and static WR(equilibrium contact angle of soil and water) of the studied soil samples were measured at three time periods of 10, 30, and 60 days after amendments application. Application of PAM, pumice, and perlite decreased dynamic and static WR significantly, whereas PVA increased it. Dynamic WR increased over time, but not significantly in PAM, pumice, and perlite treated soils. Dynamic WR increased by 40% after 60 days as compared to 10 days after PVA application. In pumice treated soil, the static WR did not vary significantly over time. Polyacrylamide and PVA increased static soil WR by 4% and 2%, respectively, at 60 days as compared to 10 days after applications. Results indicated that PAM, pumice, and perlite as soil amendments can reduce soil WR and, as a consequence, increase water retention in soil. In overall, the influence of perlite in decreasing dynamic soil WR was greater than the other amendments.