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The accumulation of heavy metals derived from livestock production poses substantial threats to soil quality and food safety in agricultural ecosystems. To evaluate these risks at a regional scale, concentrations of cadmium (Cd), arsenic (As), zinc (Zn), and copper (Cu) in animal feeds, manures, and composts were systematically surveyed across Jiangxi Province, China. Among 147 feed samples, piglet feeds exhibited the highest Zn and Cu levels (medians: 1365 mg/kg and 114 mg/kg), with exceedance rates of 87.5 % and 37.5 % relative to national limits. Cd exceeded safety thresholds in 3.2 % of swine and 13.3 % of beef cattle feeds (maxima: 2.3 and 3.3 mg/kg), while As exceedances reached 8–20 %, with a maximum of 14.5 mg/kg. In manures, median concentrations of Zn, Cu, Cd and As were 798, 262, 0.22, and 0.64 mg/kg, respectively, with Zn and Cu reaching 3–6 times their respective feed levels. Compared with manure, composting altered metal profiles, with decreased Zn and Cu concentrations and increased Cd and As concentrations. Strong feed–manure correlations in Cd, Zn, and Cu implicate feed additives as the primary sources, whereas As exhibited no significant correlation. Model simulations projected that Cd, Zn, and Cu in topsoil of Yingtan could exceed national risk screening values within 14–18 years under current manure application intensities. These findings reveal tangible ecological risks from long-term manure application under prevailing feed additive practices. Enhanced regulation of heavy metal–based additives, stricter compost quality control, and adaptive manure management are critical to mitigating soil degradation and safeguarding human health.
Zhang et al. (Sun,) studied this question.