Spatial distribution of plant-available silicon and its controlling factors in paddy fields of China

Yang, Xiaomin Song Zhaoliang Van Zwieten Lukas Sun Xiaole Yu Changxun Wang Weiqi Liu Congqiang Wang Hailong

• Status of PASi across China's paddy fields is quantified on a national scale. • Natural and anthropogenic factors control the spatial distribution of PASi content. • At least 65% of China's paddy fields are deficient in PASi. • The principal regions where PASi deficit are mainly located in southern China. • PASi content of China's paddy fields decreases with an annual rate of 0.54%. Silicon (Si) is beneficial for rice health and production by alleviating various biotic and abiotic stresses. However, the continual export of grain off-farm may result in Si deficiency for rice plants. The current levels of plant available Si (PASi) in rice paddies in China remain unclear, as do the factors that control PASi content in these soils. We conducted a nationwide sampling campaign across the paddy fields of China between 2016 and 2019, and used calcium chloride extractable Si (Si-CaCl 2) and buffered acetate extractable Si (Si-NaAc, pH = 4) to quantify PASi. We show that Si-CaCl 2 pool was mainly influenced by mean annual temperature (MAT), soil salinity, soil organic carbon (SOC), mean annual precipitation (MAP), and soil pH, suggesting both pedological and biological control mechanisms. However, the Si-NaAc pool was influenced most by soil pH, MAT and MAP, implying pedological control. Compared to data from the 1990s, the Si-NaAc content decreased by 14.1% on a national scale with an annual decline rate of 0.54%. Based on our investigation, at least 65% of China's paddy fields are deficient in PASi, which is an increase in area of ~15% over the last 20 years. The principal regions where PASi deficiency was recorded are mainly located in southern China, with the levels of Si deficiency lowering as the paddy fields are located further north. The continual off-site removal of PASi from rice grain and straw will need to be addressed through the use of Si-fertilizers, including organic amendments, to maintain a productive and sustainable rice industry in China. [ABSTRACT FROM AUTHOR] Copyright of Geoderma is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)