Elucidating the impact of three metallic nanoagrichemicals and their bulk and ionic counterparts on the chemical properties of bulk and rhizosphere soils in rice paddies.
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Growing applications of nanoagrichemicals have resulted in their increasing accumulation in agricultural soils, which could modify soil properties and affect soil health. A greenhouse pot trial was conducted to determine the effects of three metallic nanoagrichemicals on several fundamental chemical properties of a rice paddy soil, including zinc oxide nanoparticles (ZnO NPs) and copper oxide nanoparticles (CuO NPs) at 100mg/kg, and silicon oxide nanoparticles (SiO2 NPs) at 500mg/kg, as well as their bulk and ionic counterparts. The investigated soil amendments displayed significant and distinctive impact on the examined soil chemical properties relevant to agricultural production, including soil pH, redox potential, soil organic carbon (SOC), cation exchange capacity (CEC), and plant available As. For example, all amendments increased the bulk soil pH at day 47 to some extent, but the increase was substantially higher for SiO32- (37.7%) than other amendments (5.8%-13.7%). Soil Eh was elevated markedly at day 47 after the addition of soil amendments in both the bulk soil (45.9%-74.4%) and rice rhizosphere soil (20.3%-68.9%). CuO NPs and Cu2+ generally exhibited greater impact on soil chemical properties than other agrichemicals. Significantly different responses to soil amendments were observed between bulk and rhizosphere soils, suggesting the essential role of plants in affecting soil properties and their responses to environmental disturbance. Overall, our results confirmed that the tested amendments could have remarkable impacts on the fundamental chemical properties of rice paddy soils.