Phytoavailability of cadmium in rice amended with organic materials and lime: Effects of rhizosphere chemical changes and cadmium sequestration in iron plaque

Chao Xu; Shen Zheng; Daoyou Huang; Quan Zhang; Min Xiao; Jingjing Fan; Qihong Zhu; Hanhua Zhu

doi:10.1016/j.ecoenv.2023.115525

Phytoavailability of cadmium in rice amended with organic materials and lime: Effects of rhizosphere chemical changes and cadmium sequestration in iron plaque

Ecotoxicol Environ Saf. 2023 Oct 15:265:115525. doi: 10.1016/j.ecoenv.2023.115525. Epub 2023 Sep 26.

Authors

Chao Xu¹, Shen Zheng², Daoyou Huang², Quan Zhang², Min Xiao³, Jingjing Fan², Qihong Zhu², Hanhua Zhu⁴

Affiliations

¹ Key Laboratory for Agro-ecological Processes in Subtropical Region, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China. Electronic address: xuchao1388@126.com.
² Key Laboratory for Agro-ecological Processes in Subtropical Region, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
³ Key Laboratory for Agro-ecological Processes in Subtropical Region, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China; The Faculty Geography Resource Sciences, Sichuan Normal University, Chengdu 610101, China.
⁴ Key Laboratory for Agro-ecological Processes in Subtropical Region, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China. Electronic address: hhzhu@isa.ac.cn.

PMID: 37769579
DOI: 10.1016/j.ecoenv.2023.115525

Abstract

Excessive Cd in rice grains produced with acidic paddy soil is receiving increasingly widespread attention because it endangers human health. Applying organic materials (OM) and lime (L) is a common technique used to reduce Cd concentration in grains (Cd_G). Nevertheless, the mechanism by which their simultaneous application affects the Cd phytoavailability in soilrice systems remains ambiguous. In the current study, we adopted a rhizobag pot culture test to explore the influences of single application of OM [rice straw (RS), milk vetch (MV)], L, and their co-utilization on Cd phytoavailability and the associated mechanisms. The results showed that the application of RS, MV, L, L + RS (LRS), and L + MV (LMV) significantly decreased Cd_G by 26.9%, 38.2%, 48.6%, 50.0%, and 53.0%, respectively. Fe plaque (IP) formation was not affected by these treatments; however, Cd sequestration in IP (Cd_IP) was significantly reduced. Cd_IP was significantly reduced by 18.3%, 23.6%, 43.8%, 33.1%, and 41.4%, after RS, MV, L, LRS, and LMV treatments, respectively. Additionally, available Cd concentrations in rhizospheric soil (RHS) were significantly reduced by 11.5%, 14.8%, 15.1%, and 18.4%, after MV, L, LRS, and LMV treatments, respectively. Cd availability in RHS was significantly influenced by pH, dissolved organic carbon concentration, and Zn, Fe, and Mn availability. The results of the structure equation mode showed that Cd_G was mainly affected by Cd_IP, followed by Cd availability and the pH of RHS. In conclusion, the reduction of Cd_G by OM, L, and their co-utilization was the results of their combined effects of reducing Cd availability in RHS, Cd_IP, and Cd uptake by the roots. This study emphasizes that the reduction of Cd_G is a result of the dual effects of reducing Cd availability in RHS and Cd_IP after amendments application. L application alone or in conjunction with OM is an efficient practice to reduce Cd_G in acidic Cd-contaminated paddy fields.

Keywords: Cadmium; Fe plaque; Lime; Organic materials; Rhizosphere environment.