Agronomy

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19 pages, 18372 KB

Open AccessArticle

Geochemical and Ecological Assessment of Heavy Metal Contamination in a High-Cd Agricultural Ecosystem of Guangxi Karst Regions, China: Emphasis on Cd-Zn and Cd-Se Interactions

by Xiaoxuan Tang, Xinran Ke, Zhengzhou Yang, Ye Zhou, Ming Li, Nora Fung-Yee Tam, Fred Wang-Fat Lee, Steven Jing-Liang Xu, Min Pan, Tsz Wai Ng, Yik Tung Sham, Tao Lang and Zhengjie Zhu

Agronomy 2026, 16(9), 908; https://doi.org/10.3390/agronomy16090908 (registering DOI) - 30 Apr 2026

Viewed by 232

Abstract

Severe heavy metal contamination affects the karst landscapes of Guangxi Zhuang Autonomous Region, China, which are highly polluted and complex. However, integrated assessments of heavy metal sources, distribution, ecological risks, and speciation in karst agricultural soils remain limited. Additionally, there is a gap [...] Read more.

Severe heavy metal contamination affects the karst landscapes of Guangxi Zhuang Autonomous Region, China, which are highly polluted and complex. However, integrated assessments of heavy metal sources, distribution, ecological risks, and speciation in karst agricultural soils remain limited. Additionally, there is a gap regarding the interactions between cadmium (Cd), zinc (Zn), and selenium (Se) in natural rice fields. This study employed the pollution load index (PLI), ecological risk index (RI), and Positive Matrix Factorization (PMF) models to evaluate the sources and characteristics of heavy metal contamination in farmland soils. The results showed significant pollution in agricultural soils of Guangxi karst due to Cd, chromium (Cr), copper (Cu), and nickel (Ni). Among these, Cd poses the highest ecological risk. Heavy metal accumulation in the surface soil far exceeds that in deeper layers, and the main sources of Cd were contributed from soil parent material and agricultural activities. Speciation analysis revealed the high bioavailability of Cd, while Zn and Se existed in more stable forms. Despite elevated soil Cd levels, rice grains remained within the safety limits. Using transmission electron microscopy (TEM), Cd was primarily detected in the cell walls of rice stems and husks, which was attributed to Zn’s competitive uptake, reducing Cd absorption and Se forming complexes with Cd to enhance its fixation. Statistical correlations revealed positive associations between Cd in soil and rice. Cd also demonstrated a positive correlation with Se, but a negative correlation with Zn, suggesting a synergistic mechanism between Zn and Se that acts to mitigate the absorption of Cd. This study provides practical guidance for managing farmland soil heavy metal contamination and protecting agricultural soil resources in the karst areas. Full article

(This article belongs to the Special Issue Heavy Metal Pollution and Prevention in Agricultural Soils)

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22 pages, 2287 KB

Open AccessArticle

Calcium-Based Amendments Mitigate Thallium and Cadmium Transfer from Mining-Impacted Paddy Soils to Rice (Oryza sativa L.)

by Dingxing Wang, Lifang Ao, Jingxia Guo, Yan Huang, Rong Li, Tuanhui Xie, Chao Jiang, Bo Xu and Yanhui Chen

Agronomy 2026, 16(9), 893; https://doi.org/10.3390/agronomy16090893 - 28 Apr 2026

Viewed by 236

Abstract

Thallium (Tl) and cadmium (Cd) are highly toxic heavy metals that frequently co-occur in sulfide ores, posing a serious food safety risk through accumulation in rice. Although calcium-based (Ca-based) amendments have been widely applied to remediate heavy metal-contaminated soils, their effectiveness in Tl–Cd [...] Read more.

Thallium (Tl) and cadmium (Cd) are highly toxic heavy metals that frequently co-occur in sulfide ores, posing a serious food safety risk through accumulation in rice. Although calcium-based (Ca-based) amendments have been widely applied to remediate heavy metal-contaminated soils, their effectiveness in Tl–Cd co-contaminated paddy soils remains unclear. A pot experiment was conducted to evaluate four Ca-based amendments—limestone powder, dolomite powder, hydrated lime, and oyster shell powder—on Tl and Cd bioavailability and uptake in paddy soil near a mining area. Ca-based amendments effectively reduced Tl and Cd bioavailability, with DTPA-Tl reducing by 11.2–17.2% and DTPA-Cd by 8.9–21.3%. These reductions were attributed to increased soil pH and decreased DOC, Fe, and Mn in the pore water. Additionally, Ca-based amendments shifted Tl and Cd from acid-extractable to residual fractions, reducing mobility. Additionally, Ca-based amendments promoted Fe/Mn plaque formation on rice roots, reducing Tl and Cd uptake. Consequently, Tl and Cd concentrations in brown rice decreased by over 14%, with the lowest levels observed under oyster shell powder. However, Cd concentrations still exceeded the maximum permissible limit, indicating that, although Ca-based amendments show considerable potential for in situ remediation of Tl–Cd co-contaminated paddy soils, further optimization and additional measures are required to achieve safe production. Full article

(This article belongs to the Special Issue Heavy Metal Pollution and Prevention in Agricultural Soils)

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17 pages, 2718 KB

Open AccessArticle

Deciphering Heavy Metal Sources in Intensive Agricultural Soils of the Yangtze–Huaihe Watershed: Insights from High-Resolution Sampling and the APCS-MLR Modeling

by Jingtao Wu, Manman Fan, Huan Zhang and Chao Gao

Agronomy 2026, 16(7), 690; https://doi.org/10.3390/agronomy16070690 - 25 Mar 2026

Viewed by 571

Abstract

Identifying the specific sources of heavy metal accumulation in intensive agricultural landscapes is essential for ensuring soil sustainability and food security. In this study, we independently carried out a high-density regional geochemical survey and high-resolution field sampling in the Yangtze–Huaihe Watershed, Eastern China, [...] Read more.

Identifying the specific sources of heavy metal accumulation in intensive agricultural landscapes is essential for ensuring soil sustainability and food security. In this study, we independently carried out a high-density regional geochemical survey and high-resolution field sampling in the Yangtze–Huaihe Watershed, Eastern China, and used the original sample dataset to distinguish between geogenic backgrounds and anthropogenic enrichments. By employing the APCS-MLR model, four distinct pollution sources were quantitatively identified: natural pedogenesis, agricultural activities, traffic emissions, and industrial inputs. Results demonstrated that while most heavy metal concentrations remained below national safety thresholds, Cd and Hg exhibited significant topsoil enrichment, signaling potential ecological risks. Source apportionment revealed that natural sources primarily controlled As, Cr, Ni, and Pb, with the contribution ranging from 41% to 70%. In contrast, traffic emissions (e.g., tire wear and fuel combustion) emerged as the dominant source for Cd (68%), Zn (55%), and Cu (34%), while industrial activities accounted for a substantial 89% of Hg accumulation via atmospheric deposition. Notably, despite the region’s intensive cultivation, agricultural practices played a surprisingly minor role in heavy metal accumulation. These findings highlight that the accumulations from traffic and industry now account for approximately 50% of the total heavy metal load in the region. Our results underscore the critical importance of high-resolution spatial data for precise source identification and suggest that implementing vegetative buffer zones and stricter industrial emission controls are imperative to mitigate further soil degradation in similar agricultural watersheds. Full article

(This article belongs to the Special Issue Heavy Metal Pollution and Prevention in Agricultural Soils)

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16 pages, 2361 KB

Open AccessArticle

Synergistic Interaction Between Phosphorus and Biochar Enhances Cadmium Immobilization via Increased P and Fe Availability in Neutral Soil

by Fengfeng Sui, Jianjun Ma, Chenyang Qiang, Zhang Gao, Wei Zhang, Liqiang Cui, Guixiang Quan and Jinlong Yan

Agronomy 2026, 16(4), 410; https://doi.org/10.3390/agronomy16040410 - 8 Feb 2026

Viewed by 713

Abstract

To explore the effects of Fe/P-loaded biochar on neutral Cd-contaminated paddy soils and the potential synergistic effects between biochar and modifying materials, a pot experiment was conducted using neutral paddy soil with a total Cd concentration of 1.10 mg/kg. Ball milling was employed [...] Read more.

To explore the effects of Fe/P-loaded biochar on neutral Cd-contaminated paddy soils and the potential synergistic effects between biochar and modifying materials, a pot experiment was conducted using neutral paddy soil with a total Cd concentration of 1.10 mg/kg. Ball milling was employed for modified biochar production. Specifically, iron-loaded biochar (PBCFe) and phosphorus-loaded biochar (PBCP) were prepared using Fe₂O₃ and K₃PO₄, respectively. Results showed that PBCP significantly increased rice biomass while effectively inhibiting Cd uptake and accumulation in rice grains. Compared to the control (CK), P (K₃PO₄), and PBC treatments, the Cd content in rice grains under PBCP treatment decreased by 69.20%, 52.13%, and 56.06%, respectively. Moreover, compared with the treatments using single modifiers, PBCP and PBCFe effectively reduced Cd uptake and accumulation in rice tissues, especially in leaves and stems. In contrast, PBCP was more effective than PBCFe in enhancing iron plaque formation and Cd adsorption onto iron plaque. This promoted Fe uptake in rice roots, which might inhibit the upward translocation of Cd from roots to stems. Further analysis with FTIR and XPS results indicated that PBCP might be more compatible in immobilizing Cd in soil by inducing Cd-P co-deposition. Therefore, phosphorus-loaded biochar (PBCP) could be a more promising amendment for remediating Cd-contaminated alkaline rice paddy soils and improving rice quality. Full article

(This article belongs to the Special Issue Heavy Metal Pollution and Prevention in Agricultural Soils)

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15 pages, 2067 KB

Open AccessArticle

Effects of Nitrogen Form and Application Rate on Cadmium and Mineral Element Uptake and Translocation in Rice

by Yusheng Zhang, Xing Li, Xilin Fang, Xuefei Tian, Wupeng Ji, Xianglan Zeng, Zexing Chen and Hejun Ao

Agronomy 2025, 15(12), 2904; https://doi.org/10.3390/agronomy15122904 - 17 Dec 2025

Viewed by 789

Abstract

The simultaneous challenges of cadmium (Cd) contamination and mineral nutrient imbalance in paddy systems necessitate the development of effective agronomic strategies. This study systematically investigated the coordinated effects of different nitrogen fertilizer forms on the accumulation and translocation of Cd and mineral elements [...] Read more.

The simultaneous challenges of cadmium (Cd) contamination and mineral nutrient imbalance in paddy systems necessitate the development of effective agronomic strategies. This study systematically investigated the coordinated effects of different nitrogen fertilizer forms on the accumulation and translocation of Cd and mineral elements in rice. A hydroponic experiment was conducted using four N sources, including urea (U), nitrate-N (N), ammonium-N (AN), and a mixed ammonium-nitrate source (NN), which were applied at two concentrations (2.9 and 5.8 mM L⁻¹). We evaluated Cd accumulation, mineral element uptake, and translocation in rice seedlings under Cd stress. The results indicated that both the form and level of nitrogen markedly affected Cd accumulation. The AN treatment exhibited a strong Cd-reduction effect, especially at the higher nitrogen level, where it significantly reduced Cd concentration in roots and shoots by 68.75% and 26.81%, respectively. In contrast, the N treatment increased Cd accumulation in roots. Nitrogen fertilization also differentially influenced the accumulation of mineral elements, resulting in notable alterations in root Ca, Mg, Cu, and Zn concentrations, while shoot mineral concentrations remained relatively stable. Correlation and random forest analyses revealed a highly significant positive correlation between root Cd concentration and Mg and Cu concentrations, a significant negative correlation with Zn concentration, and a synergistic relationship between the translocation of Cd and that of Ca, Mg, and Cu. Analysis of ion channel tolerance rates further indicated that the AN treatment suppressed Cd uptake by reducing the permeability of root trace element channels to Cd. These findings demonstrate that nitrogen forms modulate Cd accumulation and partitioning by regulating competitive ion uptake and coordinated translocation. In particular, the AN treatment shows promising potential for reducing Cd accumulation while maintaining mineral nutrient balance, thereby providing a theoretical foundation for precise nitrogen management in Cd-contaminated paddy fields. Full article

(This article belongs to the Special Issue Heavy Metal Pollution and Prevention in Agricultural Soils)

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19 pages, 1544 KB

Open AccessArticle

Passivation Remediation of Cd-Contaminated Farmland in Yongkang, China by CaAl-LDH: A Mechanism and Application Study

by Xinzhe Lu, Nan Wei, Haochen Fang, Feng Hu, Jianjun Cheng, Rui Sun, Yining Chen, Jianyu Zhang, Yanfang Chen, Xuchuan Zhang, Kokyo Oh, Tetsushi Yonekura, Xiaochen Chen, Jia Niu and Xiaozhi Wang

Agronomy 2025, 15(10), 2354; https://doi.org/10.3390/agronomy15102354 - 7 Oct 2025

Cited by 2 | Viewed by 1410

Abstract

The enrichment of cadmium (Cd) in farmland soil poses serious risks to agricultural safety and remains challenging to remediate. This study evaluated CaAl-layered double hydroxide (CaAl-LDH) as a highly efficient and stable passivator for Cd-contaminated soil. Laboratory adsorption tests demonstrated that Cd²⁺ [...] Read more.

The enrichment of cadmium (Cd) in farmland soil poses serious risks to agricultural safety and remains challenging to remediate. This study evaluated CaAl-layered double hydroxide (CaAl-LDH) as a highly efficient and stable passivator for Cd-contaminated soil. Laboratory adsorption tests demonstrated that Cd²⁺ adsorption on CaAl-LDH followed pseudo-second-order kinetics and the Langmuir model, indicating monolayer chemisorption, with a maximum capacity of 469.48 mg·g⁻¹ at pH 6. The adsorption mechanisms include surface complexation, interlayer anion exchange, dissolution–precipitation, and isomorphic substitution. A three-year field trial in Yongkang City, China showed that CaAl-LDH promoted the transformation of Cd in rhizosphere soil from the ion exchange state (F2) to the residual state (F7) and Fe–Mn oxidized state (F5), reducing the exchangeable Cd content by 26.71%. Consequently, Cd content in rice grains decreased by 68.42% in the first year and remained over 37% lower in the second year, consistently below the national food safety limit. Future research should focus on the optimization of material’s stability and application protocol. The results demonstrate that CaAl-LDH provides a cost-effective and sustainable strategy for the in situ passivation remediation of Cd-contaminated farmland, contributing to food safety and sustainable agriculture. Full article

(This article belongs to the Special Issue Heavy Metal Pollution and Prevention in Agricultural Soils)

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21 pages, 5027 KB

Open AccessArticle

Accumulation Characteristics of Trace Elements in Leafy Vegetables with Different Heavy Metal Tolerances Under Cd and as Stress

by Yuan Meng, Liang Zhang, Liping Li, Linquan Wang, Yongfu Wu, Tao Zeng, Haiqing Shi, Zeli Chang, Qian Shi and Jian Ma

Agronomy 2025, 15(8), 1790; https://doi.org/10.3390/agronomy15081790 - 25 Jul 2025

Viewed by 2093

Abstract

This study investigates growth responses, heavy metal (Cd, As) uptake, translocation, and mineral nutrient regulation in leafy vegetables with varying heavy metal tolerance, addressing the threat posed by combined Cd and As pollution. Three high-tolerance, four moderate-tolerance, and one sensitive leafy vegetable were [...] Read more.

This study investigates growth responses, heavy metal (Cd, As) uptake, translocation, and mineral nutrient regulation in leafy vegetables with varying heavy metal tolerance, addressing the threat posed by combined Cd and As pollution. Three high-tolerance, four moderate-tolerance, and one sensitive leafy vegetable were grown in Cd+As-contaminated hydroponics. Post-harvest yields and concentrations of Cd, As, and trace elements were assessed. Results showed that (1) compared with single heavy metal treatments, the combination of Cd and As significantly increased the translocation factor of Cd in black bean sprouts and white radish sprouts by up to 83.83% and 503.2%; (2) changes in mineral nutrient concentrations in leafy vegetables were similar between single and combined heavy metal stresses, but the regulatory patterns varied among different leafy vegetable species; (3) under Cd/As exposure, high-tolerance leafy vegetables (e.g., pak choi) had strong heavy metal accumulation abilities, and heavy metal stress positively regulated mineral elements in their roots; In contrast, sensitive leafy vegetables (e.g., pea sprouts) often exhibited suppressed mineral element content in their roots, which was a result of their strategy to reduce heavy metal uptake. These results offer key insights into resistance mechanisms against combined heavy metal pollution in leafy vegetables, supporting phytoremediation efforts and safe production. Full article

(This article belongs to the Special Issue Heavy Metal Pollution and Prevention in Agricultural Soils)

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18 pages, 4023 KB

Open AccessArticle

Synergistic Effects of Silicon and Ferrous Sulfate on Reducing Arsenic and Cadmium Accumulation in Rice from Co-Contaminated Soil

by Yanlin You, Xiaodong Guo, Jianyu Chen, Zhiqin Liu, Qiuying Cai, Jinyong Yu, Wanli Zhu, Yuna Wang, Hanyue Chen, Bo Xu, Yanhui Chen and Guo Wang

Agronomy 2025, 15(6), 1422; https://doi.org/10.3390/agronomy15061422 - 10 Jun 2025

Viewed by 2412

Abstract

The co-contamination of arsenic (As) and cadmium (Cd) in paddy soils threatens rice safety, yet synergistic mitigation strategies using silicon (Si) and ferrous sulfate (FeSO₄) remain underexplored. This study integrated hydroponic and soil pot experiments to evaluate Si-FeSO₄ interactions on [...] Read more.

The co-contamination of arsenic (As) and cadmium (Cd) in paddy soils threatens rice safety, yet synergistic mitigation strategies using silicon (Si) and ferrous sulfate (FeSO₄) remain underexplored. This study integrated hydroponic and soil pot experiments to evaluate Si-FeSO₄ interactions on As/Cd accumulation and rice growth. Hydroponic trials employed 21-day-old rice seedlings exposed to 0.5 mg As(III)/Cd(II) L⁻¹ with/without 70 mg Si L⁻¹ and 30–70 mg Fe L⁻¹, followed by sequential harvesting at 14 and 21 days. Soil experiments utilized co-contaminated paddy soil (50 mg As kg⁻¹ and 1.2 mg Cd kg⁻¹) amended with Si (80 or 400 mg kg⁻¹) and Fe (100 or 1000 mg kg⁻¹), with pore water dynamics monitored over 120 days. Hydroponic results demonstrated that 70 mg Si L⁻¹ combined with 30 or 70 mg Fe L⁻¹ enhanced shoot biomass by 12–79% under As stress, while simultaneously reducing shoot As concentrations by 76–87% and Cd concentrations by 14–33%. Iron plaque induced by FeSO₄ exhibited contrasting adsorption behaviors: hydroponic roots immobilized both As and Cd (p < 0.01), whereas roots in soil primarily retained Cd (p < 0.05). In soil experiments, the optimal treatment of 100 mg Fe kg⁻¹ and 400 mg Si kg⁻¹ (Fe₁ + Si₂) increased grain biomass by 54%, while reducing As and Cd concentrations by 37% and 42%, respectively. However, a higher Fe dosage (Fe₂: 1000 mg kg⁻¹ Fe) paradoxically increased grain Cd concentrations. Mechanistically, Si amendment elevated soil pH (Δ + 0.72), facilitating Cd immobilization, while FeSO₄ lowered pH (Δ−0.07–0.53), increasing Cd mobility. A strong correlation between soluble Cd and plant uptake was observed (p < 0.01), while changes in As accumulation were unrelated to aqueous behavior. The optimized Si/Fe molar ratio of 7.95:1 effectively mitigated As and Cd co-accumulation, offering a dual-functional strategy for safe rice cultivation in contaminated soils. Full article

(This article belongs to the Special Issue Heavy Metal Pollution and Prevention in Agricultural Soils)

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20 pages, 6353 KB

Open AccessEditor’s ChoiceArticle

Effects of Wood Ash Fertilizer on Element Dynamics in Soil Solution and Crop Uptake

by Chuanzhen Jian, Toru Hamamoto, Chihiro Inoue, Mei-Fang Chien, Hiroshi Naganuma, Takehito Mori, Akihiro Sawada, Masafumi Hidaka, Hiroyuki Setoyama and Tomoyuki Makino

Agronomy 2025, 15(5), 1097; https://doi.org/10.3390/agronomy15051097 - 30 Apr 2025

Cited by 13 | Viewed by 8148

Abstract

Wood ash, a byproduct of woody biomass power generation, has potential as an alternative K fertilizer due to its high K content and pH-raising properties. However, concerns remain about heavy metal contaminants like Cr and the limited understanding of element dynamics in soil–solution–crop [...] Read more.

Wood ash, a byproduct of woody biomass power generation, has potential as an alternative K fertilizer due to its high K content and pH-raising properties. However, concerns remain about heavy metal contaminants like Cr and the limited understanding of element dynamics in soil–solution–crop systems after wood ash’s application. This study examined the effects of 1% (w/w) wood ash on element dynamics and komatsuna (Brassica rapa var. perviridis) uptake in low-K soil through a pot experiment. XRD was used to analyze mineral composition, SEM-EDS to observe surface and elemental properties, and XANES to examine Cr speciation in wood ash. Soil solution analysis covered macro- and micronutrients, heavy metals, anions, pH, and DOC, while crop element concentrations and aboveground dry weight were also quantified. The chemical speciation of Cu and Cr in a soil solution was modeled using Visual MINTEQ. Wood ash significantly increased K concentrations (from 17 mg/L to 650 mg/L) in the soil solution, along with Ca, Mg, P, and Mo, while reducing Ni, Mn, Zn, and Cd levels. Komatsuna K uptake surged from 123 mg/kg to 559 mg/kg, leading to a 3.31-fold biomass increase. Notably, the Cd concentration in the crops dropped significantly from 0.709 to 0.057 mg/kg, well below the Codex standard of 0.2 mg/kg. Although Cu and Cr concentrations rose in the soil solution, crop uptake remained low due to >99% complexation with fulvic acid, as confirmed by Visual MINTEQ modeling. This study confirms that wood ash is an effective K fertilizer, but emphasizes the need for risk mitigation strategies to ensure safe and sustainable agricultural application. Full article

(This article belongs to the Special Issue Heavy Metal Pollution and Prevention in Agricultural Soils)

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16 pages, 2691 KB

Open AccessArticle

Heavy Metals Distribution and Source Identification in Contaminated Agricultural Soils: Isotopic and Multi-Model Analysis

by Tingting Mu, Benyi Cao, Min Yang, Xinhong Gan, Lin Chen, Xiaohan Wang, Ming Li, Yuanyuan Lu and Jian Xu

Agronomy 2025, 15(4), 812; https://doi.org/10.3390/agronomy15040812 - 26 Mar 2025

Cited by 4 | Viewed by 2734

Abstract

Heavy metal pollution in agricultural soil has been tightly associated with anthropogenic emissions. Although there are many studies that focus on a regional scale, the source identification of heavy metal contamination on a field scale around industrial areas remains unclear. The average concentrations [...] Read more.

Heavy metal pollution in agricultural soil has been tightly associated with anthropogenic emissions. Although there are many studies that focus on a regional scale, the source identification of heavy metal contamination on a field scale around industrial areas remains unclear. The average concentrations in topsoils of Hg, Cd, As, Pb, Cr, Ni, Zn, and Cu were 2.07, 0.13, 8.56, 42.3, 81.1, 37.3, 105, and 43.8 mg kg⁻¹, respectively. The enrichment of Hg was particularly presented on topsoils, with the highest single pollution index (Pi) (9.00) and ecological risk index (Eri) (922) values. An integrated methodology was employed in source identification of heavy metals contamination, especially for Hg, including Pearson’s and PCA analysis, soil profile morphology, mathematical modeling, and Hg isotope analysis. Results revealed that the concentrations of Hg decreased as a function of depth, suggesting Hg contamination was an anthropogenic source and can be supported by Hg isotope analysis. The negative Δ¹⁹⁹Hg values of the residual Hg (F4-Hg) and soil profile in 80–100 cm deviate from those of the soil profiles in 0–80 cm, indicating exogenous input of Hg occurred in the study area. According to the UNMIX model, the contribution of coal combustion, agricultural activities, parent material, and industrial/traffic emissions to Hg accumulation in soils were 66.2%, 16.9%, 9.81%, and 7.0%, respectively. However, the contribution rates calculated with the PMF model of mixed industrial source, traffic emissions, and parent material were 71.4%, 27.8%, and 0.8%, respectively. This study can accurately quantify and identify the factors contributing to heavy metal contamination in agricultural soil on a field scale. Full article

(This article belongs to the Special Issue Heavy Metal Pollution and Prevention in Agricultural Soils)

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22 pages, 19774 KB

Open AccessEditor’s ChoiceArticle

A Fusion XGBoost Approach for Large-Scale Monitoring of Soil Heavy Metal in Farmland Using Hyperspectral Imagery

by Xuqing Li, Huitao Gu, Ruiyin Tang, Bin Zou, Xiangnan Liu, Huiping Ou, Xuying Chen, Yubin Song, Wei Luo and Bin Wen

Agronomy 2025, 15(3), 676; https://doi.org/10.3390/agronomy15030676 - 11 Mar 2025

Cited by 20 | Viewed by 3261

Abstract

Heavy metal pollution of farmland is worsened by the excessive introduction of heavy metal elements into soil systems, posing a substantial threat for global food security and human health. The traditional laboratory-based methods for monitoring soil heavy metals are limited for large-scale applications, [...] Read more.

Heavy metal pollution of farmland is worsened by the excessive introduction of heavy metal elements into soil systems, posing a substantial threat for global food security and human health. The traditional laboratory-based methods for monitoring soil heavy metals are limited for large-scale applications, while hyperspectral imagery data-based methods still face accuracy challenges. Therefore, a fusion XGBoost model based on the superposition of ensemble learning and packaging methods is proposed for large-scale monitoring with high accuracy of soil heavy metal using hyperspectral imagery. We took Xiong’an New Area, Hebei Province, as the study area, and acquired heavy metal content using chemical analysis. The XGB-Boruta-PCC algorithm was used for precise feature selection to obtain the final modeled spectral response features. On this basis, the performance indicators of the Optuna-optimized XGBoost model were compared with traditional linear and nonlinear models. The optimal model was extended to the entire region for drawing the spatial distribution map of soil heavy metal content. The results suggested that the XGB-Boruta-PCC method effectively achieved double dimensionality reduction of high-dimensional hyperspectral data, extracting spectral response features with a high contribution, which, combined with the XGBoost model, exhibited greater general estimation accuracies for heavy metal (Pb) in farmland (i.e., Pb: R² = 0.82, RMSE = 11.58, MAE = 9.89). The results of the mapping indicated that there were exceedances for the southwest and parts of the west over the research region. Factories and human activities were the potential causes of heavy metal Pb contamination in farmland. In conclusion, this innovative method can quickly and accurately achieve monitoring large-scale soil heavy metal contamination in farmland, with ZY-1-02E spaceborne hyperspectral imagery proving to be a reliable tool for mapping soil heavy metal in farmland. Full article

(This article belongs to the Special Issue Heavy Metal Pollution and Prevention in Agricultural Soils)

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13 pages, 1382 KB

Open AccessEditor’s ChoiceArticle

Evaluating the Level of Total Mercury Present in the Soils of a Renowned Tea Production Region

by Jinghua Xu, Ruijia Xie, Liping Liu and Zhiqun Huang

Agronomy 2025, 15(2), 435; https://doi.org/10.3390/agronomy15020435 - 10 Feb 2025

Cited by 1 | Viewed by 2648

Abstract

Total mercury pollution in oolong tea garden soils was comprehensively investigated in this study. Soil samples were collected from 146 villages in a famous oolong tea production area. The total mercury content in the soils ranged from 0.025 to 0.296 mg/kg, with a [...] Read more.

Total mercury pollution in oolong tea garden soils was comprehensively investigated in this study. Soil samples were collected from 146 villages in a famous oolong tea production area. The total mercury content in the soils ranged from 0.025 to 0.296 mg/kg, with a median of 0.105 mg/kg. According to the Soil Accumulation Index Method, 67.81% of samples were pollution-free, 31.51% had pollution levels from none to moderate, and 0.68% were moderately polluted. The PMF model revealed that natural geochemical processes were the main mercury source, contributing 72.4%, with some from transportation, coal combustion, and industrial activities. Most values were below the HQ threshold, suggesting low non-carcinogenic risk from mercury in most soils. Further research is needed to understand mercury’s bioaccumulation in tea leaves and assess short- and long-term exposure risks for a better understanding of its long-term impacts on the tea industry and human health. Full article

(This article belongs to the Special Issue Heavy Metal Pollution and Prevention in Agricultural Soils)

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20 pages, 2718 KB

Open AccessArticle

Protective Role of Triacontanol (Myricyl Alcohol) Towards the Nutrients Uptake and Growth in Brassica rapa L. Under Cadmium Stress

by Shakil Ahmed, Aleeza Akram, Rehana Sardar, Nasim Ahmad Yasin, Mariam Fatima, Muhammad Jabbar and Maximilian Lackner

Agronomy 2024, 14(12), 2916; https://doi.org/10.3390/agronomy14122916 - 6 Dec 2024

Cited by 3 | Viewed by 2717

Abstract

Agricultural soil contaminated with heavy metals gradually affects crop yield and its quality. Cadmium (Cd) is a heavy metal that severely affects crop yield, such as Brassica rapa L. (turnip), which is grown in arid and semiarid regions worldwide. It also affects seed [...] Read more.

Agricultural soil contaminated with heavy metals gradually affects crop yield and its quality. Cadmium (Cd) is a heavy metal that severely affects crop yield, such as Brassica rapa L. (turnip), which is grown in arid and semiarid regions worldwide. It also affects seed germination and seedling development. The exogenous application of triacontanol (Tria, C₃₀H₆₁OH) has the potential to alleviate heavy metal-induced toxic effects and promote crop yield even in contaminated environments. Therefore, in the present work, Tria was tested to lessen the toxicity of Cd to turnip plants. The current study aimed to determine how seed priming and foliar application of Tria (10 and 20 ppm) influence the morphophysiological and yield characteristics of turnip plants under Cd-induced growth inhibition. Cd reduced turnip growth by affecting its morphology, biomass, and yield parameters. On the other hand, Tria at 20 ppm via SP+FS (seed priming + foliar spray) enhanced plant growth by increasing its root and leaf fresh weight by 80 and 54%, Chl a (59%), Chl b (27%), phenolic content (39%), and mineral contents of Mg (60%) and K (39%) compared with those in the plants treated with only Cd. DPPH (2,2-diphenyl-1-picrylhydrazyl) activity was enhanced by up to 48% and ascorbic acid content by up to 96% in Cd-treated plants. These findings suggest that Tria application via both methods improved turnip yield by increasing tolerance to Cd toxicity. Therefore, this study paves the way for further exploration into a very cheap and economical way of enhancing crop production against Cd stress for farmers. Full article

(This article belongs to the Special Issue Heavy Metal Pollution and Prevention in Agricultural Soils)

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