Effects of silica nanoparticles on root characteristics of Zoysia grass and rill detachment capacity in soils treated with hydromulch

Abstract

It is well known that hydromulching is an appropriate method for controlling runoff and soil erosion. Also, the addition of silica nanoparticles (Nsi) in soil in various ways has been found to be a beneficial technique to improve root characteristics. However, few studies have explored the effects of silica nanoparticles produced from rice husk (as a crop that is exceedingly plentiful in many Asian countries) on soil erosion processes, particularly rill erosion due to overland flow in deforested lands. To fill this gap, this study has evaluated the impacts of root growth induced by silica nanoparticles (Nsi) on the rill detachment capacity (Dc) and erodibility (Kr) in the hydromulched soil samples, compared to the control soil samples in deforested lands of Northern Iran. Dc has been measured by a hydraulic flume under four bed slopes (7.3, 13.9, 18.5, and 23.4%) and five water discharges (0.25, 0.36, 0.47, 0.59, and 0.72 L m−1 s−1) with six replications per experiment. Moreover, after the application of hydromulch on soil surface and the growth of grass, root traits (root diameter, root length, root biomass and root weight density) were measured. The results show that rill detachment capacity was lower (on average −59%) in the hydromulched soil with the presence of silica nanoparticles compared to the untreated plot (P < 0.01). Dc was negatively correlated with the root length, root biomass and root weight density. Conversely, as the root diameter increased, the Dc increased. Rill erodibility, obtained by regressing Dc on shear stress, was noticeably lower (-86%) in the hydromulched soil with the presence of silica nanoparticles compared to the bare plot. Overall, the results of this study confirm that the effects of silica nanoparticles on growth development of root traits and the reduction of soil erosion appear to be impactful, especially on steep slopes.