Eco-engineered rice-husk nanosilica enhances soil structural stability and reduces detachment capacity in paddy fields

Previous studies have shown that silica nanomaterials produced from rice residues, such as husk, can influence several soil properties. However, their effects on soil detachment capacity and structural characteristics in rice paddy fields remain poorly quantified. This study evaluated the effects of nanosilica derived from rice husk on wet aggregate stability, plasticity index, and detachment capacity in paddy soils of Northern Iran under different flow discharges simulated in a hydraulic flume. The nanosilica used in this study was produced by acid extraction followed by controlled heating, and was incorporated into field plots at a 2% amendment level. Results showed that wet aggregate stability and plasticity index significantly increased by 32% and 27%, respectively, in the nanosilica-treated soils compared with the untreated control. Conversely, the average soil detachment capacity decreased by 49%, also in this case significantly. Multivariate analysis indicated strong interrelations among the measured properties and distinctly separated the amended soils from the control group. Linear regressions between detachment capacity and shear stress or stream power showed that nanosilica reduced soil erodibility and increased the threshold resistance to particle detachment under increasing flow power. Overall, the findings demonstrate that rice-husk-derived nanosilica enhances aggregate cohesion and substantially reduces soil vulnerability to concentrated flow erosion in paddy systems.