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 surrounding soil in mining areas generally suffers from severe pollution, characterized primarily by multi-metal contamination, and poses significant challenges in restoration and safe utilization. Therefore, it is urgent to explore low-cost restoration and safe utilization technologies that can achieve simultaneous treatment and utilization. This study selected a typical lead-zinc mining area in eastern Yunnan, China, where there is severe heavy metal pollution. It collected 15 common varieties of castor plants and systematically studied their absorption, accumulation, translocation, and removal characteristics of four heavy metal elements (Cd, Pb, Cu, Zn). The results showed that the heavy metal pollution in the mining area was extremely severe. Castor plants have a strong tolerance to heavy metal stress. There were significant differences in the absorption and accumulation of heavy metals among different castor varieties. The root parts mainly accumulated Pb, the stem parts mainly accumulated Cd, and the seeds had a higher ability to accumulate Cu. In terms of restoration potential, the Tong Castor No. 24, Fen Castor No. 10, and Zi Castor No. 3 plants had relatively large restoration potential. However, considering both biomass and heavy metal removal capacity, Dian Castor No, 2 Zi Castor No. 3, Dian Castor No. 5 plants were more ideal and could be applied in the restoration of heavy metal complex pollution soil in mining areas.

Addressing the environmental challenges posed by the massive stockpiling of phosphogypsum (PG) has become a global concern, highlighting the urgency of developing large-scale, low-cost and resource-efficient utilization approaches for PG. This study was conducted in the rocky desertification areas of southwestern China, where land and water resources are scarce. Two land creation techniques—layered reconstruction (GA) and integrated construction (GB)—were adopted with modified PG to systematically investigate their impacts on soil properties and potato growth, yield and quality. The results showed that both techniques significantly improved soil conditions and enhanced potato yield and quality, with each presenting distinct characteristics in soil improvement. Specifically, the GA technique showed relatively better performance in soil nutrient enrichment, while the GB technique was more conducive to enhancing soil enzyme activity. Compared with the local red soil control, both techniques reduced heavy metal accumulation in potato tubers; however, Pb and Cd contents still exceeded national food safety limits, indicating potential food safety risks. In summary, land creation using modified PG can effectively increase arable land area, improve soil quality in rocky desertification regions, and simultaneously promote potato yield and quality. Nevertheless, as the current results are based on a single-season field trial, they cannot reflect the long-term patterns of heavy metal migration and accumulation. Therefore, for large-scale application, it is necessary to strengthen the monitoring of heavy metal levels in imported soil and long-term regional environmental impacts so as to ensure the quality and safety of agricultural products from reclaimed land.

To investigate the effects of co-application of KMnO₄-modified biochar and organic fertilizer on the physicochemical properties, carbon and nitrogen content, and growth of Chinese cabbage in acidic red soil. Using typical acidic red soil from Yunnan as the test substrate, this study conducted a pot experiment with four treatment groups: control (CK), organic fertilizer alone (OF), biochar combined with organic fertilizer (BOF), and potassium permanganate KMnO₄-modified biochar combined with organic fertilizer (Mn-BOF), each at three application rates (1500, 3000, and 4500 kg/ha). The results indicated that KMnO₄ modification significantly improved the pore structure of biochar, increasing its specific surface area by 22.776%, and successfully loaded manganese onto the biochar surface. Compared with the CK, all treatments significantly increased soil pH, organic matter (SOM), alkali-hydrolyzable nitrogen (AN), available phosphorus (AP), and available potassium (AK), with the effects gradually increasing as the application rate rose; the 4500 kg/ha treatment yielded the best results. The Mn-BOF treatment was most effective in increasing soil organic carbon (SOC), total nitrogen (TN), soluble organic carbon and nitrogen (DOC/DON), and microbial carbon and nitrogen (MBC/MBN); simultaneously, the Mn-BOF treatment significantly promoted the growth of Chinese cabbage, with yield under the 4500 kg/ha treatment increasing by 158.58% compared to CK (under pot-grown conditions), and soluble total sugars, chlorophyll, and vitamin C content also significantly increased. In summary, Mn-BOF can improve the fertility of acidic red soil, particularly demonstrating excellent performance in enhancing key carbon and nitrogen components such as SOC, TN, DOC, DON, MBC and MBN. This, in turn, promotes increased yield and improved quality of Chinese cabbage, providing feasible guidance for enhancing soil fertility in highland agricultural systems.