Impacts of nano-clay addition to soils: a meta-analysis

Nano-sized clay particles exhibit unique physicochemical properties within soil matrices relevant to several areas of applied environmental sciences. The amendment of soils with nano-clays in field, lab, and greenhouse settings has been increasingly studied over recent decades from various disciplinary perspectives. In general, nano-clay as a soil amendment is seen as a potentially effective and economically feasible method for managing soil resources. However, no comprehensive review and quantification of the impacts of nano-clay amendment on soil physical, chemical, and biological properties has been undertaken, which limits its uptake and application. Here, we provide a review of the impacts of nano-clay addition in soil, using a meta-analytical approach considering soil health parameters (e.g., organic carbon, water retention, cation exchange, pH, pollutant concentration). Preliminary results synthesizing field and lab experiments indicate a wide range of positive effect sizes across key soil properties, with only limited benefits occurring in specific cases. Our results highlight the significant potential of nano-clay as a soil amendment in diverse applications, especially when coupled with the economic and logistical suitability of nano-clay amendment globally.