China is vigorously promoting green, environmentally friendly, and sustainable agricultural practices, with a strong emphasis on the efficient recycling of biomass resources. In particular, in the field of fertilizer use, the country has clearly stated the need to reduce the application of chemical fertilizers, improve fertilizer use efficiency, and promote the substitution of chemical fertilizers with organic fertilizers. This study aims to explore the effects of different application rates of biochar-based organic fertilizers on soil-available nutrients, corn growth, and the inhibition of cadmium absorption and transfer in corn through field experiments. The experiment consisted of 10 treatments, including a blank control (CK), organic fertilizer at 1500 kg/ha (T1), 3000 kg/ha (T2), and 4500 kg/ha (T3), biochar-based organic fertilizer I at 1500 kg/ha (T4), 3000 kg/ha (T5), and 4500 kg/ha (T6), and biochar-based organic fertilizer II at 1500 kg/ha (T7), 3000 kg/ha (T8), and 4500 kg/ha (T9). The results indicate that the surface of the modified biochar exhibited significant fracturing and breakage, with an increase in pore size and pore number. Mn elements were successfully loaded onto the surface of the biochar, and the number of certain original functional groups was increased. Among all treatments, the T9 treatment (biochar-based organic fertilizer II at 4500 kg/ha) showed the best results in improving soil pH, organic matter, alkali-hydrolyzable nitrogen, and available potassium, significantly increasing these parameters by 0.69 units, 19.01%, 22.20%, and 36.24%, respectively, compared to the control. The T8 treatment (biochar-based organic fertilizer II at 3000 kg/ha) showed the best effect in reducing soil-available cadmium and cadmium content in corn grains, with reductions of 32.84% and 26.28%, respectively, compared to CK. The T9 treatment also had the most significant effect on increasing corn yield, plant height, crown width, and leaf length, with improvements of 64.08%, 0.16 m, 21.05%, and 9.28%, respectively, compared to CK. Correlation analysis revealed that corn yield, plant height, crown width, and leaf length were significantly positively correlated with soil pH, organic matter, alkali-hydrolyzable nitrogen, available phosphorus, and available potassium, while they were significantly negatively correlated with soil-available cadmium content. In summary, the application of organic fertilizers and biochar-based organic fertilizers I and II can improve soil pH, organic matter, alkali-hydrolyzable nitrogen, available phosphorus, and available potassium in cadmium-contaminated soils while also significantly enhancing corn yield and growth traits. Moreover, these fertilizers effectively reduce available cadmium in the soil and cadmium content in corn grains. Among the treatments, biochar-based organic fertilizer II performed the best in promoting crop growth, enhancing soil nutrient content, and reducing both soil-available cadmium and corn grain cadmium content, with the effectiveness ranking as follows: biochar-based organic fertilizer II > biochar-based organic fertilizer I > organic fertilizer. The results of this study provide a new approach to the resource utilization of agricultural waste and offer a theoretical basis for safe crop production in the context of heavy metal pollution.

This work aimed to explore safe techniques for the utilization of farmland surrounding mining areas contaminated with heavy metals—specifically cadmium (Cd) and lead (Pb)—in order to achieve food security in agricultural production. A potato variety (Qingshu 9) with high Cd and Pb accumulation was used as the test crop, and seven treatments were set up: control (CK), special potato fertilizer (T1), humic acid (T2), special potato fertilizer + humic acid (T3), biochar (T4), calcium magnesium phosphate fertilizer (T5), and biochar + calcium magnesium phosphate fertilizer (T6). The remediation effect of the combined application of different passivators on the accumulation of cadmium and lead in potatoes in the contaminated soil of a mining area was studied. The results showed that, compared with CK, all passivator treatments improved the physical and chemical properties of the soil and reduced the available Cd and Pb content in the soil and in different parts of potatoes. The T6 treatment yielded the most significant reduction in the available Cd and Pb content in the soil, the Cd and Pb content in the potato pulp, and the enrichment factor (BCF) and transfer factor (TF) of the potatoes. Compared with T4 and T5, the content of available Cd in the soil decreased by 1.22% and 4.71%, respectively; the soil available Pb content decreased by 3.13% and 3.02%, respectively; the Cd content in the potato pulp decreased by 68.08% and 31.02%, respectively; and the Pb content decreased by 31.03% and 20.00%, respectively. The results showed that the application of biochar combined with calcium magnesium phosphate fertilizer had a better effect in terms of reducing the available Cd and Pb content in the soil and the Cd and Pb content in the potato flesh compared to their individual application. Biochar and calcium magnesium phosphate fertilizer can synergistically increase the content of soil available nutrients and reduce the activity of heavy metals in the soil to prevent the transfer and accumulation of cadmium and lead to potatoes, as well as improve their yield and quality. The results of this study provide technical support for safe potato planting and agricultural soil management.

Chinese cabbage (Brassica pekinensis (Lour.) Rupr.) is rich in many vitamins and many minerals and is an important green vegetable in people’s daily diet. Soil heavy metal Cd content exceeding safe values has a toxic effect on the growth of vegetables, which seriously affects human health. Biochar can effectively stabilize heavy metals in polluted soil, and phosphogypsum can improve the physical and chemical properties of soil and promote the growth of crops. To explore the remediation effect of biochar combined with different amounts of phosphogypsum on Cd-contaminated soil and the safe production of agricultural products, a pot experiment was conducted with corn straw biochar and harmless phosphogypsum as the test materials, and Chinese cabbage as the test plant. The soil pH; the alkali-hydrolyzed nitrogen content; the available phosphorus, potassium, and Cd content in the soil; the fresh weight of the Chinese cabbage; the Cd content in the edible part of the Chinese cabbage; and the vitamin C, chlorophyll, and soluble sugar contents in the leaves were measured and analyzed. The results showed that among all the treatments, the T3 and T4 treatments were the most effective in enhancing the soil pH and soil available nutrient content. Compared with CK, the T3 and T4 treatments significantly enhanced the soil pH by 0.27 and 0.29 units, respectively, and significantly increased alkali-hydrolyzed nitrogen content by 16.25% and 14.04%, available phosphorus content by 22.98% and 22.87%; and available potassium content by 8.50% and 10.13%. In addition, among all the treatments, the T3 treatment had the best effect on reducing the soil available Cd content and the Cd content in the edible part of the Chinese cabbage, which were significantly reduced by 17.05% and 49.35%, respectively, compared with CK, and the T3 treatment had the best effect on improving the yield and quality of the Chinese cabbage, significantly increasing the fresh weight of the Chinese cabbage by 31.86%, the soluble sugar level by 9.54%, the vitamin C level by 15.38%, and the chlorophyll level by 13.28%, compared with CK. In summary, 3000 kg/hm² of biochar combined with 3000 kg/hm² of phosphogypsum can significantly reduce the effectiveness of soil Cd, prevent the transfer of Cd to Chinese cabbage, reduce the ecological risk of Cd, and improve the yield and quality of Chinese cabbage. The results provide a theoretical basis for the safe production of agricultural products in Cd-contaminated soil and promote the recycling of resources for the benefit of the environment.

The problem of the contamination of soils with high background values of heavy metals has attracted increasing attention. In this paper, the contents, spatial distribution characteristics and correlations of five heavy metals in seven types of arable soils with different soil-forming matrices were analyzed by using Kriging spatial interpolation, descriptive statistics and correlation analysis to clarify the spatial distribution of heavy metals in different soil-forming matrices, and to explore the influence of parent rocks on the spatial distribution and concentration of heavy metals. The results showed that the Cd contents of the seven soil-forming parent materials exceeded the background values recorded for soils in Yunnan Province and that metamorphic rocks such as mudstone, argillaceous rock, purple rock, and carbonate rock exceeded the risk screening values. The average Pb, Cu, and As contents were lower than the background values recorded for soils in Yunnan Province and smaller than the risk screening values for agricultural land. Carbonate areas have a large area of contamination, while metamorphic mudstone areas have a relatively small percentage of contamination. The correlations of heavy metals in different soil-forming matrices varies, and the source of each element and its correlation can be further analyzed and verified by means such as the source analysis method. The results of this study are crucial for pollution prevention and the analysis of the source of heavy metal soil contamination.

This study analyzes the heavy metal pollution in cultivated soils developed from different parent materials in Yunnan Province and assesses their risk levels. The results show significant regional differences in soil heavy metal pollution, greatly influenced by the type of parent material. Cadmium (Cd) pollution is most severe in multiple parent material soil regions, particularly in areas with carbonate and purple rocks, exhibiting a high pollution risk. Other heavy metals such as zinc (Zn), copper (Cu), and lead (Pb) also show varying degrees of enrichment in different parent material zones, posing potential pollution risks. The soil pollution levels of heavy metals were classified using the geo-accumulation index method. It was found that soils developed from carbonate rocks and purple rocks have the most severe heavy metal pollution, while soils from quartzitic rocks, acidic crystalline rocks, and basalt exhibit relatively lower pollution levels. By analyzing the characteristics of heavy metal pollution in different parent materials, this study provides a scientific basis for regional soil pollution management and sustainable agricultural development.

In recent years, soil heavy metal pollution has become increasingly serious, particularly Cd and Pb pollution, and heavy metals have been accumulating in soil–crop systems, posing great risks to human health. In this study, four Chinese cabbage varieties with different Cd and Pb accumulation traits were cultivated using hydroponics and transcriptome sequencing technology to reveal the response mechanism of Chinese cabbage to Cd and Pb stress at the molecular level. The numbers of upregulated genes in Harmony Express (H) and Ziwei F1 (F) were 2904 and 3004, respectively, under Cd stress (0 mg/L vs. 80 mg/L), whereas the numbers of upregulated genes in Green Crown (L) and Suzhou Green (S) were 3424 and 2724, respectively, under Pb stress (0 mg/L vs. 1200 mg/L). GO enrichment analysis revealed that 52 functional subgroups were enriched in H0 vs. H80 and F0 vs. F80, and 79 functional subgroups were enriched in L0 vs. L1200 and S0 vs. S1200. KEGG enrichment indicated that secondary metabolite biosynthesis, metabolic pathways, and phenylpropanoid biosynthesis are important regulators of the response to Cd and Pb stress in Chinese cabbage. In addition, genes related to antioxidant enzymes (e.g., CAT and glutathione transferase), metal transporter proteins (e.g., ABC), mitogen-activated protein kinases, and calmodulin were significantly differentially expressed, suggesting that they are jointly involved in the detoxification of Chinese cabbage in response to heavy metal stress. In total, 881 and 858 differentially expressed genes (DEGs) in the transcription factor family responded to Cd and Pb stress, respectively. This study reveals the response mechanism of Chinese cabbage to Cd and Pb stress at the molecular level and provides a theoretical basis for the cultivation of low-Cd and low-Pb-enriched varieties and the mining of heavy metal tolerance genes.