Effect of oxide nanoparticles on soil water retention curve and soil tensile strength

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Generally, nanotechnology plays very important roles in various applied scientific fields. Iron and magnesium nanoparticles can cause positive or negative changes in physical and mechanical properties of soil, especially in long periods. The aim of this study was to investigate multi-year effects of nanoparticles on soil water retention and tensile strength of the aggregates. Samples of a loamy soil were mixed with 1%, 3%, and 5% levels of MgO or Fe3O4 nanoparticles, in three replications, and incubated for three years. Water contents were measured at different matric suctions of 0, 1, 2, 4, 6, 10, 30, 100, 1500 kPa. The van Genuchten model was fitted to the moisture data. Tensile strength was measured on 2–4 mm aggregates at matric suctions of 30 and 1500 kPa. The results of this research showed that the levels of 1% and 3% of nano-iron oxide significantly increased water retention to 0.64 and 0.63, respectively, compared to the control (0.39) and 5% nano-magnesium oxide (0.19), which is probably due to the increase of adsorption surfaces in the treated soils. Water content at field capacity and permanent wilting point conditions in 5% magnesium nano-oxide treatment were decreased to 0.25 and 0.13, respectively, compared to other treatments, due to the increased soil vulnerability and affecting soil fine pores. Iron oxide nanoparticles did not have any significant effect on soil tensile strength. Based on the results of this study, physical and mechanical properties of soil could be affected by use of nanoparticles.