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

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 p...

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Main Authors: Qiying Zhang, Weijian Wu, Yingyue Zhao, Xiaoyu Tan, Yang Yang, Qingru Zeng, Xiao Deng
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Agriculture
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Online Access:https://www.mdpi.com/2077-0472/15/10/1052
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author Qiying Zhang
Weijian Wu
Yingyue Zhao
Xiaoyu Tan
Yang Yang
Qingru Zeng
Xiao Deng
author_facet Qiying Zhang
Weijian Wu
Yingyue Zhao
Xiaoyu Tan
Yang Yang
Qingru Zeng
Xiao Deng
author_sort Qiying Zhang
collection DOAJ
description 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<sub>2</sub>CO<sub>3</sub>, K<sub>2</sub>SO<sub>4</sub>, and K<sub>2</sub>SiO<sub>3</sub> 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<sub>2</sub>SiO<sub>3</sub> application (TB-K<sub>2</sub>SiO<sub>3</sub>) and single tillering-stage K<sub>2</sub>SO<sub>4</sub> (T-K<sub>2</sub>SO<sub>4</sub>) 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<sub>2</sub>SiO<sub>3</sub> 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<sub>2</sub>SiO<sub>3</sub>. In contrast, T-K<sub>2</sub>SO<sub>4</sub> 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<sub>2</sub>SiO<sub>3</sub> application at the tillering and booting stages or single K<sub>2</sub>SO<sub>4</sub> application at the tillering stage ensures safe rice production in Cd-contaminated soils, offering scalable remediation strategies for paddy ecosystems.
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spelling doaj-art-6b5cd46cce7543a89daa7810cef492112025-08-20T03:14:32ZengMDPI AGAgriculture2077-04722025-05-011510105210.3390/agriculture15101052Optimizing Potassium Fertilization Combined with Calcium–Magnesium Phosphate Fertilizer Mitigates Rice Cadmium Accumulation: A Multi-Site Field TrialQiying Zhang0Weijian Wu1Yingyue Zhao2Xiaoyu Tan3Yang Yang4Qingru Zeng5Xiao Deng6College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, ChinaCollege of Environment and Ecology, Hunan Agricultural University, Changsha 410128, ChinaCollege of Environment and Ecology, Hunan Agricultural University, Changsha 410128, ChinaCollege of Environment and Ecology, Hunan Agricultural University, Changsha 410128, ChinaCollege of Environment and Ecology, Hunan Agricultural University, Changsha 410128, ChinaCollege of Environment and Ecology, Hunan Agricultural University, Changsha 410128, ChinaCollege of Environment and Ecology, Hunan Agricultural University, Changsha 410128, ChinaAlkaline 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<sub>2</sub>CO<sub>3</sub>, K<sub>2</sub>SO<sub>4</sub>, and K<sub>2</sub>SiO<sub>3</sub> 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<sub>2</sub>SiO<sub>3</sub> application (TB-K<sub>2</sub>SiO<sub>3</sub>) and single tillering-stage K<sub>2</sub>SO<sub>4</sub> (T-K<sub>2</sub>SO<sub>4</sub>) 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<sub>2</sub>SiO<sub>3</sub> 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<sub>2</sub>SiO<sub>3</sub>. In contrast, T-K<sub>2</sub>SO<sub>4</sub> 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<sub>2</sub>SiO<sub>3</sub> application at the tillering and booting stages or single K<sub>2</sub>SO<sub>4</sub> application at the tillering stage ensures safe rice production in Cd-contaminated soils, offering scalable remediation strategies for paddy ecosystems.https://www.mdpi.com/2077-0472/15/10/1052riceCd immobilizationpotassium managementalkaline fertilizer
spellingShingle Qiying Zhang
Weijian Wu
Yingyue Zhao
Xiaoyu Tan
Yang Yang
Qingru Zeng
Xiao Deng
Optimizing Potassium Fertilization Combined with Calcium–Magnesium Phosphate Fertilizer Mitigates Rice Cadmium Accumulation: A Multi-Site Field Trial
Agriculture
rice
Cd immobilization
potassium management
alkaline fertilizer
title Optimizing Potassium Fertilization Combined with Calcium–Magnesium Phosphate Fertilizer Mitigates Rice Cadmium Accumulation: A Multi-Site Field Trial
title_full Optimizing Potassium Fertilization Combined with Calcium–Magnesium Phosphate Fertilizer Mitigates Rice Cadmium Accumulation: A Multi-Site Field Trial
title_fullStr Optimizing Potassium Fertilization Combined with Calcium–Magnesium Phosphate Fertilizer Mitigates Rice Cadmium Accumulation: A Multi-Site Field Trial
title_full_unstemmed Optimizing Potassium Fertilization Combined with Calcium–Magnesium Phosphate Fertilizer Mitigates Rice Cadmium Accumulation: A Multi-Site Field Trial
title_short Optimizing Potassium Fertilization Combined with Calcium–Magnesium Phosphate Fertilizer Mitigates Rice Cadmium Accumulation: A Multi-Site Field Trial
title_sort optimizing potassium fertilization combined with calcium magnesium phosphate fertilizer mitigates rice cadmium accumulation a multi site field trial
topic rice
Cd immobilization
potassium management
alkaline fertilizer
url https://www.mdpi.com/2077-0472/15/10/1052
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