Effects of different soil types on silicon isotope fractionation of rice

A plot experiment was carried out to explore the effects of different soil types on Si isotope composition and fractionation of rice. Rice (Oryza sativa L. cv. Jia 58) was grown in red soil, black soil and cinnamon soil, respectively. Soil chemical properties, rice dry weight, rice Si content, rice Si isotope composition were determined. The results indicated that different types of soil had a remarkable impact on the rice Si-isotopic fractionation. The Si isotope fractionation factors (α_Pre-Dsi) of rice grown in red soil, black soil and cinnamon soil were 0.9988, 0.9978 and 0.9975, respectively, illustrating that the extent of Si isotope fractionation of rice planted in cinnamon soil was the strongest, followed by rice in black soil and rice in red soil. Correlation analysis showed that the δ³⁰ Si values of rice (bulk and leaves) were significant correlated with the contents of organic matter, available Si, free Fe oxide, free Al oxide and pH values of soils (P < 0.01), indicating that rice Si-isotopic signature might be primarily affected by p H values, organic matter content, available Si content of soils and the extent of soil weathering since the contents of free Fe oxide and free Al oxide increase with weathering. The results provide a theoretical basis for using Si isotope tracing technology to explore the model of Si cycle in nature. (authors)