Reducing Grain Cadmium in Wheat: Synergistic Effects of Compost Co‐Applied With Zinc, Manganese, or Phosphorus in Calcareous Soil

ABSTRACT Soil contamination with cadmium (Cd) poses a serious threat to food safety and human health. However, remediating Cd‐contaminated calcareous soils remains highly challenging. In this study, fermented cow manure and wheat straw were used as organic amendments (OA), and zinc (Zn), manganese (Mn), and phosphorus (P) were applied as mineral elements. The effects of OA alone (4, 8, and 12 g kg −1 ) and the combined application of OA (8 g kg −1 ) with Zn (0.55 g kg −1 as ZnCl 2 ), Mn (0.1 g kg −1 as MnCl 2 ), or P (0.1 g kg −1 as KH 2 PO 4 ) on Cd accumulation in wheat grown in Cd‐contaminated calcareous soil were investigated in a pot experiment. The results showed that the combined application of Zn and OA was the most effective in reducing Cd concentration in the wheat plants, achieving a 31.29%–59.17% decrease in grain, stems, and roots. This effect may be attributed to decreased rhizospheric Cd availability. Additionally, under this treatment, the available Zn concentration in the rhizosphere was significantly lower than in the non‑rhizosphere, suggesting that wheat plants actively immobilized Zn. X‐ray diffraction (XRD) analysis further indicated that Zn in the rhizosphere soil was likely transformed into ZnLi 4 P 2 and Zn 3 TeAs 6 Pb 3 O 18 . Collectively, these processes likely contributed to reduced rhizospheric Cd availability and lower Cd accumulation in wheat plants. Therefore, the combined application of Zn and OA represents a promising strategy for mitigating Cd contamination in wheat grown in Cd‐contaminated calcareous soils.