Optimizing Potassium Fertilization Combined with Calcium–Magnesium Phosphate Fertilizer Mitigates Rice Cadmium Accumulation: A Multi-Site Field Trial

Qiying Zhang, Weijian Wu, Yingyue Zhao, Xiaoyu Tan, Yang Yang, Qingru Zeng and Xiao Deng ()
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Qiying Zhang: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China
Weijian Wu: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China
Yingyue Zhao: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China
Xiaoyu Tan: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China
Yang Yang: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China
Qingru Zeng: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China
Xiao Deng: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China

Agriculture, 2025, vol. 15, issue 10, 1-16

Abstract: Alkaline fertilizers demonstrate significant potential in mitigating rice cadmium (Cd) accumulation, yet the combined effects of calcium–magnesium phosphate (CMP) with potassium (K) fertilizer types and split application strategies remain unclear. Through multi-site field trials in Cd-contaminated paddy soils, we evaluated split applications of K 2 CO 3 , K 2 SO 4 , and K 2 SiO 3 at tillering and booting stages following basal CMP amendment. Optimized K regimes reduced brown rice Cd concentrations (up to 89% reduction) compared to conventional fertilization. Notably, at the CF site, split K 2 SiO 3 application (TB-K 2 SiO 3 ) and single tillering-stage K 2 SO 4 (T-K 2 SO 4 ) achieved brown rice Cd levels of 0.13 mg/kg, complying with China’s food safety standard (≤0.20 mg/kg), thereby eliminating non-carcinogenic risks. Mechanistically, TB-K 2 SiO 3 enhanced soil pH by 0.21 units and increased available K (AK) by 50.26% and available Si (ASi) by 21.35% while reducing Cd bioavailability by 43.55% compared to non-split K 2 SiO 3 . In contrast, T-K 2 SO 4 elevated sulfate-driven Cd immobilization. Structural equation modeling prioritized soil available Cd, root Cd, and antagonistic effects of AK and ASi as dominant factors governing Cd accumulation. The integration of CMP with split K 2 SiO 3 application at the tillering and booting stages or single K 2 SO 4 application at the tillering stage ensures safe rice production in Cd-contaminated soils, offering scalable remediation strategies for paddy ecosystems.

Keywords: rice; Cd immobilization; potassium management; alkaline fertilizer (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2025
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