Zinc is an essential trace element for human and plant growth and development. Exploiting naturally Zn-rich soil resources represents an important pathway to develop green characteristic agriculture, improve the nutritional quality of agricultural products, and advance agricultural sustainability aligned with the United Nations Sustainable Development Goals (SDGs2, 3 and 15). To clarify the geochemical characteristics and bioavailability of soil zinc in cultivated lands of the mid-low hilly region in southwestern Henan, and to scientifically evaluate the exploitation potential of Zn-rich land resources, this study selected the farming area of Fangcheng County, Henan Province, as its research object. Based on 1:50,000 land-quality geochemical survey data, 1602 topsoil samples and 61 paired wheat-grain–root-zone soil samples were collected. Multiple statistical approaches, including descriptive statistics, Universal Kriging spatial interpolation, Pearson correlation analysis and segmented regression, were adopted to systematically investigate Zn concentrations, spatial-distribution patterns, element paragenesis relationships and wheat Zn-accumulation characteristics in cultivated soils. Furthermore, the resource potential of Zn-rich land was assessed according to the Specification for Delineation and Identification of Natural Zn-Rich Land (DD2025-04). The results showed the following: (1) The mean Zn concentration of topsoil was 72.3 mg/kg (
N = 1602, after removing 3σ outliers), which was higher than the national soil background value (67 mg/kg). With a coefficient of variation of 23.0%, soil Zn exhibited moderate enrichment and relatively uniform distribution. Its spatial pattern was dominated by geomorphic types, showing a north-high–south-low trend. Significant Zn-enrichment advantages were found in hilly areas, yellow-cinnamon soils, and regions covered by alluvial–proluvial and residual-slope parent materials, whereas Zn concentrations were markedly low in strongly alkaline soils. (2) Soil Zn was significantly positively correlated with Cd (r = 0.62), Cu (r = 0.51), V (r = 0.54) and Fe
2O
3 (r = 0.57), and moderately positively correlated with Se (r = 0.41) and Mo (r = 0.43). These correlations indicate homologous soil-forming parent-material sources and Zn-adsorption–enrichment mechanisms mediated by Fe-Mn oxides. The paragenetic relationship between soil Zn and Cd implies that heavy-metal ecological risks should be considered simultaneously during Zn-rich-land exploitation to guarantee ecological sustainability of cultivated land. (3) The average Zn concentration in wheat grains was 28.48 mg/kg, and the mean bioconcentration factor (BCF) was 0.42 (
N = 61, averaged from individual sample-pair ratios), demonstrating a moderate Zn-accumulation capacity of wheat. Only a moderate correlation existed between total soil Zn and wheat-grain Zn, suggesting that high total soil Zn concentrations do not necessarily produce high-Zn crops. (4) Soil pH regulated Zn bioavailability: BCF was positively correlated with pH for samples with pH < 6.5 (R
2 = 0.116,
p = 0.013), while a non-significant negative trend was observed for the subgroup pH ≥ 6.5 (R
2 = 0.269,
p = 0.153). Wheat presented relatively high Zn-accumulation potential under neutral-pH conditions. Nevertheless, the observational dataset cannot confirm pH = 6.5 as a strict optimum threshold, which needs further validation through field-controlled experiments. Either extremely acidic or alkaline conditions may reduce available Zn supply via Zn leaching loss or hydroxide precipitation. (5) In accordance with DD2025-04, Zn-rich soils accounted for 21.85% of the study area, and Zn-enriched wheat grains occupied 21.31%, indicating abundant reserves of Zn-rich land resources. These findings can provide geochemical support for the scientific utilization of Zn-rich cultivated land, industrial layout of Zn-enriched wheat, and precise cultivated-land quality management in the hilly areas of southwestern Henan, promoting sustainable utilization of soil resources and nutrition-sensitive agricultural development.
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