Editorial

15 pages, 3495 KiB

Open AccessEditorial

Technologies for Environmental Ecological Restoration and Agricultural Sustainability Are the Focus of Future Safeguarded Agriculture Development

by Haoming Chen, Da Tian and Zhen Li

Agronomy 2024, 14(1), 12; https://doi.org/10.3390/agronomy14010012 - 20 Dec 2023

Viewed by 1030

Abstract

Global agricultural production is facing unprecedented challenges as the environment becomes increasingly polluted. Governments, scientists, companies and farmers are beginning to focus on appropriate environmental remediation and sustainable agricultural technologies and practices. Innovative environmental adaptation/remediation technologies have been developed and validated, including physical/chemical [...] Read more.

Global agricultural production is facing unprecedented challenges as the environment becomes increasingly polluted. Governments, scientists, companies and farmers are beginning to focus on appropriate environmental remediation and sustainable agricultural technologies and practices. Innovative environmental adaptation/remediation technologies have been developed and validated, including physical/chemical remediation, green sorbents and bioremediation. The development of environmental remediation technologies has provided additional tools and methods for global agri-environment and food security. The aim of this Special Issue is to bring together 21 cutting-edge research papers covering the latest developments in soil conditions, inorganic pollution, organic pollution, remediation technologies and monitoring methods. The four themes of the Special Issue are “Improvement of agricultural soil properties”, “Remediation of potentially toxic element pollution”, “Remediation of organic pollution” and “Ecosystem and crop assessment”. Based on the results of this Special Issue, we find that combining the latest environmental pollution problems with advanced remediation technologies, continuously promoting technological innovation and policy support, and developing integrated new technologies for environmental protection will be future areas of research for sustainable agro-environmental development. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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Research

Jump to: Editorial

19 pages, 4145 KiB

Open AccessArticle

Spatial Correlation Evolution and Driving Factors of Wheat Production in China Based on Social Network Analysis

by Xinru Lv, Han Zhang, Yunhua Zhang and Junli Li

Agronomy 2023, 13(2), 515; https://doi.org/10.3390/agronomy13020515 - 10 Feb 2023

Cited by 2 | Viewed by 1381

Abstract

Understanding the spatial correlation network of inter-provincial wheat production is vital for ensuring food security and achieving sustainable agricultural development in China. However, the spatial correlation characteristics of wheat production and their determinants remain unclear. In this study, an improved gravity model was [...] Read more.

Understanding the spatial correlation network of inter-provincial wheat production is vital for ensuring food security and achieving sustainable agricultural development in China. However, the spatial correlation characteristics of wheat production and their determinants remain unclear. In this study, an improved gravity model was used to calculate the spatial correlation of inter-provincial wheat production in China based on available panel data from 2000 to 2020. The spatial-temporal evolution characteristics and the driving factors of the spatial correlation network of inter-provincial wheat production in China were analyzed using social network analysis (SNA) and a quadratic assignment procedure (QAP). The findings indicated that (1) the spatial correlation of inter-provincial wheat production first increased and then decreased. The network density increased from its lowest value (0.2598) in 2000 to its maximum value (0.2782) in 2016 and then continued to fluctuate. (2) The spatial correlation network of inter-provincial wheat production presented a “core-periphery” distribution pattern for the major wheat-producing areas (such as Jiangsu, Anhui, and Hubei) and non- major wheat-producing areas (such as Jilin, Qinghai, Guangxi, and Beijing), and the roles of the blocks in the network varied with time and space. (3) The implementation of grain-related policies (such as the abolition of agricultural taxes, the implementation of industry nurturing agriculture, and the minimum grain purchase price policy) positively affected the development of the spatial correlation network of wheat production. Since the implementation of the minimum purchase price policy for wheat in 2006, the network density reached its maximum value (0.2782), the network efficiency reached its minimum value (0.5985), and the stability of the network structure greatly improved. (4) The interactions between the internal natural conditions and the external socioeconomic factors promoted the construction of a spatial correlation network for wheat production. The differences in geographical adjacency, land resources, temperature, and sunlight hours were all significant at the 1% level, highlighting the substantial impact of these factors on the spatial correlation intensity of wheat production in China. This study provides a reference for the development of cooperative cross-regional wheat production and the formulation of distinct policies for the production of wheat and other grains. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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12 pages, 1520 KiB

Open AccessArticle

Green Remediation Technology for Total Petroleum Hydrocarbon-Contaminated Soil

by Min-Siou Lin, Chin-Yuan Huang, Yuan-Chung Lin, Sun-Long Lin, Yin-Hsiu Hsiao, Pei-Chun Tu, Pei-Cheng Cheng and Shu-Fen Cheng

Agronomy 2022, 12(11), 2759; https://doi.org/10.3390/agronomy12112759 - 06 Nov 2022

Cited by 6 | Viewed by 1676

Abstract

In order to improve the bioremediation efficiency of petroleum-contaminated soil, five test groups were selected in this study, including native bacteria, Acinetobacter venetianus, Vetiveria zizanioides L., and Vetiveria zizanioides L. combined with Acinetobacter venetianus and biochar to compare the degradation efficiency of [...] Read more.

In order to improve the bioremediation efficiency of petroleum-contaminated soil, five test groups were selected in this study, including native bacteria, Acinetobacter venetianus, Vetiveria zizanioides L., and Vetiveria zizanioides L. combined with Acinetobacter venetianus and biochar to compare the degradation efficiency of petroleum-contaminated soil. The results of the study showed that after a six-month bioremediation, there was no significant difference between the native bacteria and the A.V. bacteria group in the removal efficiency of TPH, and the proportion of degradable TPH accounts for about 50~70%. The removal efficiency of TPH could be increased by 18.1–29% by increasing the phytoremediation of Vetiveria zizanioides L. The cultivation of Vetiveria zizanioides L. could not only stabilize the soil’s pH and conductivity but could also increase the soil’s bacterial abundance. It was suggested that bioremediation could be carried out through the combination of native bacteria and the planting of Vetiveria zizanioides L. Although the addition of biochar to the soil was able to improve the remediation effect of Vetiveria zizanioides L., it would increase the soil conductivity and reduce the abundance of soil bacteria. Therefore, it was recommended to reduce the conductivity of biochar before adding it, which may improve processing efficiency. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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18 pages, 1663 KiB

Open AccessArticle

Suitability Evaluation of Tea Cultivation Using Machine Learning Technique at Town and Village Scales

by Wenwen Xing, Cheng Zhou, Junli Li, Weiyin Wang, Jingchi He, Youjun Tu, Xiu Cao and Yunhua Zhang

Agronomy 2022, 12(9), 2010; https://doi.org/10.3390/agronomy12092010 - 25 Aug 2022

Cited by 8 | Viewed by 1836

Abstract

Suitability evaluation of tea cultivation is very important for improving the yield and quality of tea, which can avoid blind expansion and achieve sustainable development; however, to date, relevant research at town and village scales is lacking. This study selected Xinming Township in [...] Read more.

Suitability evaluation of tea cultivation is very important for improving the yield and quality of tea, which can avoid blind expansion and achieve sustainable development; however, to date, relevant research at town and village scales is lacking. This study selected Xinming Township in Huangshan City, Anhui Province, as the study area, which is the main production area of Taiping Houkui Tea—one of the ten most famous teas in China. We proposed a machine learning-based tea cultivation suitability evaluation model by comparing logistic regression (LR), extreme gradient boosting (XGBoost), adaptive boosting (AdaBoost), gradient boosting decision tree (GBDT), random forest (RF), Gaussian Naïve Bayes (GNB), and multilayer perceptron (MLP) to calculate the weight accuracy of the evaluation factors. We then selected 12 factors, including climate, soil, terrain, and ecological economy factors, using the RF with the highest accuracy to calculate the evaluation factor weights and obtained the suitability evaluation results. The results show that the highly suitable area, moderately suitable area, generally suitable area, and unsuitable area land categories for tea cultivation were 14.13%, 27.25%, 32.46%, and 26.16%, respectively. Combined with field research, the highly suitable areas were mainly distributed in northwest Xinming Town, which is in line with the distribution of tea cultivation at the Xinming township level. The results provide a scientific reference to support land allocation decisions for tea cultivation and sustainable green agricultural development at the town and village scales. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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13 pages, 2991 KiB

Open AccessArticle

Functional Analysis and Precise Location of m-1a in Rice

by Qing Dong, Jia Shen, Fang Wang, Yaocheng Qi, Chaoqiang Jiang, Chaolong Zu and Tingchun Li

Agronomy 2022, 12(7), 1706; https://doi.org/10.3390/agronomy12071706 - 19 Jul 2022

Cited by 1 | Viewed by 1208

Abstract

The T-DNA insertion technique is widely used in molecular breeding for its stable inheritance and low copy number in the plant genome. In our experiment, a transfer DNA (T-DNA) insertion grain of m-1a in rice was identified. Phenotypic analysis revealed that the grains [...] Read more.

The T-DNA insertion technique is widely used in molecular breeding for its stable inheritance and low copy number in the plant genome. In our experiment, a transfer DNA (T-DNA) insertion grain of m-1a in rice was identified. Phenotypic analysis revealed that the grains appeared chalky and became extensive. The epidermis was shrinking. Meanwhile, the amylose contents of the seeds decreased significantly, and the expression of the most starch synthesis genes was obviously downregulated. Using the whole-genome sequencing and chromosome step method, the insertion position was uncovered and only located in Chr11 between 23266185 and 23266186 bp. These results may provide material for opening up new T-DNA insertion position points and a theoretical basis for rice molecular breeding. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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13 pages, 13683 KiB

Open AccessEditor’s ChoiceArticle

Remediation of Lead Contamination by Aspergillus niger and Phosphate Rocks under Different Nitrogen Sources

by Yi Feng, Liangliang Zhang, Xiang Li, Liyan Wang, Kianpoor Kalkhajeh Yusef, Hongjian Gao and Da Tian

Agronomy 2022, 12(7), 1639; https://doi.org/10.3390/agronomy12071639 - 08 Jul 2022

Cited by 8 | Viewed by 1526

Abstract

Co-application of Aspergillus niger (A. niger) and phosphate rocks (PR) has been practiced by environmentalists for lead (Pb) remediation. The secretion of organic acid by A. niger usually dominates the dissolution of PR and Pb immobilization. In this study, two types [...] Read more.

Co-application of Aspergillus niger (A. niger) and phosphate rocks (PR) has been practiced by environmentalists for lead (Pb) remediation. The secretion of organic acid by A. niger usually dominates the dissolution of PR and Pb immobilization. In this study, two types of PR (fluorapatite (FAp) and phosphogypsum (PG)) were investigated in Pb remediation by A. niger under three different forms of nitrogen (ammonium, nitrate, and urea). Our results reveal that the formation of pyromorphite and lead oxalate contributed to Pb removal by the combination of A. niger with FAp and PG. PG showed a significant capability for Pb remediation compared with FAP, over 94% of Pb vs. 50%. Compared with nitrate and urea, ammonium significantly decreased Pb cation concentrations from 1500 mg/L to 0.4 mg/L. Due to ammonium containing sulfate, the lead sulfate formed also contributed to Pb removal. However, nitrate stimulated A. niger to secrete more oxalic acid (~1400 mg/L) than ammonium and urea (~200 mg/L), which can form insoluble lead oxalate. These insoluble minerals can reduce the availability of removed Pb. Despite the efficacy of both ammonium and nitrate for Pb remediation, our findings suggest that nitrate is the primary candidate in this regard due to high oxalic acid secretion. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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13 pages, 2587 KiB

Open AccessArticle

High Level of Iron Inhibited Maize Straw Decomposition by Suppressing Microbial Communities and Enzyme Activities

by Mengcan Jin, Hao Guan, Wenjie Zhang, Da Tian, Junling Wei, Yusef Kianpoor Kalkhajeh and Hongjian Gao

Agronomy 2022, 12(6), 1286; https://doi.org/10.3390/agronomy12061286 - 27 May 2022

Cited by 5 | Viewed by 1549

Abstract

In order to study the linkages between the crop straw decomposition rate and the change in soil biological properties after the straw returned to the soil with different iron (Fe²⁺) contents, a 180-day incubation experiment was performed to examine the decomposition [...] Read more.

In order to study the linkages between the crop straw decomposition rate and the change in soil biological properties after the straw returned to the soil with different iron (Fe²⁺) contents, a 180-day incubation experiment was performed to examine the decomposition of maize straw (MS) under three Fe²⁺ levels, i.e., 0, 0.3, and 1 mg g⁻¹. Enzyme activities regarding straw decomposition and microbial communities under 0 and 1 mg g⁻¹ Fe addition were also detected. The results showed that Fe²⁺ addition significantly inhibited MS decomposition. This was evidenced by the higher contents of hemicellulose, cellulose, and lignin in Fe²⁺ treatments on day 180. High-Fe addition (1 mg g⁻¹) decreased the activity of Laccase (Lac) by 71.82% compared with control on day 30. Furthermore, the principal coordinates analysis (PCoA) indicated that high-Fe mainly affected the bacterial community. In particular, it suppressed the relative abundance of Microbacteriaceae in phylum Actinomycota that, in turn, is a potential decomposer of crop straw by secreting lignocellulolytic enzymes. A high level of Fe²⁺ inhibited the decomposition of hemicellulose, cellulose, and lignin in MS by reducing the relative abundance of phylum Actinobacteria in bacteria and suppressing Lac activity. Our findings provide guidance for returning crop straws in soils with high-Fe content. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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17 pages, 3104 KiB

Open AccessArticle

Assessment of Soil Contamination Using GIS and Multi-Variate Analysis: A Case Study in El-Minia Governorate, Egypt

by Amr A. Hammam, Wagih S. Mohamed, Safa Essam-Eldeen Sayed, Dmitry E. Kucher and Elsayed Said Mohamed

Agronomy 2022, 12(5), 1197; https://doi.org/10.3390/agronomy12051197 - 16 May 2022

Cited by 19 | Viewed by 3391

Abstract

The issue of soil contamination is one of the most important subjects that interests decision-makers all over the world. It is also related to soil fertility and food security. The soils adjacent to the drains in Egypt suffer from increasing concentration of heavy [...] Read more.

The issue of soil contamination is one of the most important subjects that interests decision-makers all over the world. It is also related to soil fertility and food security. The soils adjacent to the drains in Egypt suffer from increasing concentration of heavy metals, which negatively affects soil and crop quality. Precise spatial distribution maps of heavy metals are an essential key to mitigating the negative impacts on the ecosystem. Sixty random soil locations adjacent to the El-Moheet drainage were chosen on the west side of the Nile River, El-Minia governorate, Egypt. Six heavy metals (Cr, Co, Cu, Cd, Pb, and Zn) were selected to generate their spatial pattern maps using ordinary Kriging (OK). Principal component analysis (PCA) and contamination factors (CF) were applied to evaluate soil contamination levels in the study area. The results showed that the Gaussiang model was a high fit for soil pH, and Pb, the Exponential model was fit for EC, Stable model was fit for OC, Co, Cu, and Cd. In addition, the Spherical model was fit for both Cr and Zn. The MSE values were close to zero in all selected metals, while the values of RMSSE were close to one. The results showed that the soil heavy metal concentrations were grouped into two clusters using PCA. Furthermore, three contamination degrees were obtained (moderate, considerable, and very high), with about 70.7% of the study area characterized by considerable heavy metals concentration, where the average heavy metals concentration (mg kg⁻¹) in this degree was 91.23 ± 19.5, 29.44 ± 5.2, 53.83 ± 10.2, 1.12 ± 0.3, 36.04 ± 18.0, and 101.29 ± 35 for Cr, Co, Cu, Cd, Pb, and Zn, respectively. The current results reflect the mismanagement and use of low-quality water for irrigation in the study area, which increased the toxic element concentration in soil surface layers. In the end, the results of spatial distribution maps of pollutants and their degrees could support decision-makers as a basis for developing appropriate mitigation plans for heavy metals. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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17 pages, 2638 KiB

Open AccessArticle

Combination of Biochar and Phosphorus Solubilizing Bacteria to Improve the Stable Form of Toxic Metal Minerals and Microbial Abundance in Lead/Cadmium-Contaminated Soil

by Weiwei Lai, Yuanyi Wu, Chaonan Zhang, Yimamu Dilinuer, Lhamo Pasang, Yuqi Lu, Yuhong Wang, Haoming Chen and Zhen Li

Agronomy 2022, 12(5), 1003; https://doi.org/10.3390/agronomy12051003 - 22 Apr 2022

Cited by 29 | Viewed by 2878

Abstract

Biochar adsorption and microbial remediation have great potential in the field of soil remediation, but since both are stressed by high concentrations of toxic heavy metals when applied alone, combining the two may become an effective remediation method. In this study, the application [...] Read more.

Biochar adsorption and microbial remediation have great potential in the field of soil remediation, but since both are stressed by high concentrations of toxic heavy metals when applied alone, combining the two may become an effective remediation method. In this study, the application effect of phosphorus-solubilizing bacteria (PSB) combined with rice husk biochar on the remediation of Pb/Cd-mixed pollution and the form differences of toxic metal were studied qualitatively and quantitatively. Compared with the contaminated soil, the combined remediation of biochar and PSB significantly increased the pH, carbon and phosphorus by 9.0%, 299.4% and 157.0%. Meanwhile, combined remediation increased the total microbial, bacterial and fungal biomass by 92.11%, 103.13% and 138.10%. This confirmed that the addition of biochar increased the soil nutrients and provided good conditions for PSB or native microorganisms to flourish. The extraction results showed that the stable form of Pb/Cd with biochar + PSB was better than that with biochar/PSB alone. Combined remediation significantly increased the acid-soluble and non-bioavailable fraction of Pb/Cd by 5/15 times and 14/5.8 times in contaminated soil. The acid-soluble and non-bioavailable fractions are the main fraction of toxic metals after combined remediation (>80%). The acid-soluble and non-bioavailable fractions were mainly carbonates and phosphate-based Pb/Cd minerals (XRD analysis). PCA and a GWB model further confirmed that the release of pH and phosphorus was the key to the passivation of Pb/Cd in a short time. Meanwhile, the combination of the biochar (phosphorus supply guarantee) and PSB (acid-soluble phosphorus function) can reduce soil acidification and improve soil nutrients, thus increasing microbial abundance in contaminated soil, even more than that in non-contaminated soil. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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14 pages, 2907 KiB

Open AccessArticle

Does Straw Returning Amended with Straw Decomposing Microorganism Inoculants Increase the Soil Major Nutrients in China’s Farmlands?

by Zhifeng He, Xinrun Yang, Jing Xiang, Zelu Wu, Xinyi Shi, Ying Gui, Manqiang Liu, Yusef Kianpoor Kalkhajeh, Hongjian Gao and Chao Ma

Agronomy 2022, 12(4), 890; https://doi.org/10.3390/agronomy12040890 - 06 Apr 2022

Cited by 8 | Viewed by 2159

Abstract

Although straw-decomposing microbial inoculants (SDMI) are capable to generally promote the fertility of straw-amended soils, their impact on the release of individual soil major nutrients remains controversial. Additionally, the combined effects of SDMI and environment/management on various forms of nutrients remain poorly documented. [...] Read more.

Although straw-decomposing microbial inoculants (SDMI) are capable to generally promote the fertility of straw-amended soils, their impact on the release of individual soil major nutrients remains controversial. Additionally, the combined effects of SDMI and environment/management on various forms of nutrients remain poorly documented. To fill these research gaps, we conducted a meta-analysis study using 1214 paired observations from 132 field trials in China. Our results showed that SDMI significantly increases the total and available concentrations of nitrogen, phosphorus, and potassium in soil (p < 0.05), although increases in nutrients varied with different conditions. Moreover, mean annual precipitation (MAP) had significant correlations with the effects of SDMI-amended straw on soil total nitrogen (p = 0.008) and available nitrogen (p = 0.0006). The effect of SDMI-amended straw on soil total phosphorus and soil available potassium was mainly correlated with soil organic matter (p = 0.032) and MAP (p = 0.049), respectively. Our findings indicate that SDMI-amended straw can have a measurable impact on the status of soil major nutrients. In particular, the application of SDMI-amended rice straw with an initial C/N ratio of ≤15 to neutral soils in temperate and subtropical monsoon climates is a promising strategy. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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11 pages, 1016 KiB

Open AccessArticle

Transformation of Chromium Speciation during High Hexavalent Chromium-Contaminated Soil Remediation by CPS and Biostimulation

by Qing Wu, Ruihan Wan, Qiannan Li, Wenjun Mo, Jieqiong Liu, Caiyun Zhao and Sen Peng

Agronomy 2022, 12(4), 801; https://doi.org/10.3390/agronomy12040801 - 26 Mar 2022

Cited by 2 | Viewed by 1539

Abstract

To address the secondary pollution problem of chemical reduction and the defects of a long bioremediation period for the soil around a chromium (Cr) salt plant in China, calcium polysulfide (CPS) combined with biostimulation (adding nutrient solution with glucose and urea) was used [...] Read more.

To address the secondary pollution problem of chemical reduction and the defects of a long bioremediation period for the soil around a chromium (Cr) salt plant in China, calcium polysulfide (CPS) combined with biostimulation (adding nutrient solution with glucose and urea) was used to reduce and stabilize hexavalent chromium [Cr(VI)] in the soil. The results showed that the remediation effect of adding CPS and nutrient solution was better than that of CPS alone for Cr(VI)-contaminated soil. An amount of 2.15% CPS with the Cr(VI) concentration reduced to approximately 330.0 mg/kg was selected as the optimal reducing agent dosage. Following the addition of 11 g/kg glucose and 13 g/kg urea, the degradation rate of Cr(VI) reached over 92% after 3 days, and the water-soluble fraction decreased by 95.6% after 40 days. The stability of the Cr was significantly enhanced. The correlation and regression analyses of Cr speciation indicated that the water-soluble fraction had significant negative correlations with the iron-manganese (Fe-Mn) oxide-bound fraction and the organic matter-bound fraction. There were significant negative correlations between the exchangeable fraction and the carbonate-bound fraction as well as extremely significant positive correlations between the Fe-Mn oxide-bound fraction and the organic matter-bound fraction. It was speculated that both the Fe-Mn oxide-bound fraction and the organic matter-bound fraction were transformed from the water-soluble fraction, and the exchangeable fraction and the carbonate-bound fraction were mutually transformed. This study enables us to acquire more knowledge about the speciation transformation of Cr in soil and provides an efficient, low-cost, and low-risk technology for the remediation of high Cr(VI)-contaminated soil. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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12 pages, 3490 KiB

Open AccessArticle

The Utilization of Phosphogypsum as a Sustainable Phosphate-Based Fertilizer by Aspergillus niger

by Da Tian, Jingjing Xia, Ningning Zhou, Meiyue Xu, Xiang Li, Liangliang Zhang, Shuhua Du and Hongjian Gao

Agronomy 2022, 12(3), 646; https://doi.org/10.3390/agronomy12030646 - 06 Mar 2022

Cited by 19 | Viewed by 2709

Abstract

Phosphogypsum (PG) is a by-product of the phosphorus (P) chemical industry, and usually contains ~2% residual phosphate. The P in PG would cause P pollution in the environment by the way of long-term stacking. Phosphate-solubilizing fungi (PSF) can effectively promote the release of [...] Read more.

Phosphogypsum (PG) is a by-product of the phosphorus (P) chemical industry, and usually contains ~2% residual phosphate. The P in PG would cause P pollution in the environment by the way of long-term stacking. Phosphate-solubilizing fungi (PSF) can effectively promote the release of P from insoluble phosphate. The aim of this study was to investigate the P release capacity between tricalcium phosphate (TCP) and PG by Aspergillus niger (ANG) via flask experiment. At the same time, the application of PG fertilizer (PGF) in soil was also performed. The dry biomass of ANG between TCP and PG treatment reached the maximum value of 0.71 and 0.38 g, respectively, after five days of incubation. The maximum P concentrations released from PG and TCP by ANG is five and seven days, i.e., 128 and 1103 mg/L, respectively. PG has a similar P release ratio compared with TCP by ANG, i.e., 52% vs. 55%. In the soil incubation experiment, PGF can significantly increase the soil available P content and continuously maintain the high concentration (17.2 mg/kg) after four weeks of incubation. The utilization of PG by ANG via the PGF is a feasible pathway to increase the soil P content, especially for the sustainable use of phosphate resources. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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13 pages, 3550 KiB

Open AccessArticle

The Effects of Chemical Oxidation and High-Temperature Reduction on Surface Functional Groups and the Adsorption Performance of Biochar for Sulfamethoxazole Adsorption

by Jifei Hou, Jialin Yu, Wenxuan Li, Xiudan He and Xuede Li

Agronomy 2022, 12(2), 510; https://doi.org/10.3390/agronomy12020510 - 18 Feb 2022

Cited by 8 | Viewed by 2217

Abstract

Biochar is a beneficial adsorbent for the treatment of organic pollutants in the environment. The association of oxygen functional groups and adsorption behaviors has not been well investigated. In this paper, the oxidation-modified biochar (O-BC) and the reduction-modified biochar (R-BCX) were prepared by [...] Read more.

Biochar is a beneficial adsorbent for the treatment of organic pollutants in the environment. The association of oxygen functional groups and adsorption behaviors has not been well investigated. In this paper, the oxidation-modified biochar (O-BC) and the reduction-modified biochar (R-BCX) were prepared by Co²⁺/peroxymonosulfate chemical oxidation and high-temperature reduction, respectively. The modified biochars were used to remove sulfamethoxazole (SMX) from water, and the adsorption amounts of biochar followed the order of R-BC700 (14.66 mg·L⁻¹) > O-BC (4.91 mg·L⁻¹) > BC (0.16 mg·L⁻¹). Additionally, the effects of water chemical conditions (i.e., ionic strength, solution pH and humic acid (HA) concentration) on the adsorption of SMX on biochar, were further investigated. Combining physical adsorption, X-ray electron spectroscopy, and zeta potentiometer characterization techniques, the effect of functional groups on the adsorption mechanism was further explored, revealing the importance of various oxygen functional groups for SMX adsorption. The results showed that C=O and C=C, resulting in π–π interaction, were in favor of the adsorption of SMX, while C-O was not conducive to the adsorption of SMX, due to the steric hindrance and the negative surface charge. Additionally, the hydrophobic effect of the biochar was also one of the adsorption mechanisms. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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12 pages, 12259 KiB

Open AccessArticle

The Sorption of Sulfamethoxazole by Aliphatic and Aromatic Carbons from Lignocellulose Pyrolysis

by Gang Chu, Zifeng Han, Zimo Wang, Defeng Kong, Wenxiu Qin, Youbin Si, Guozhong Wang and Christian E. W. Steinberg

Agronomy 2022, 12(2), 476; https://doi.org/10.3390/agronomy12020476 - 14 Feb 2022

Cited by 5 | Viewed by 1990

Abstract

Massive biomass waste with lignocellulose components can be used to produce biochar for environmental remediation. However, the impact of lignocellulose pyrolysis on biochar structure in relation to the sorption mechanism of ionizable antibiotics is still poorly understood. In this paper, diverse techniques including [...] Read more.

Massive biomass waste with lignocellulose components can be used to produce biochar for environmental remediation. However, the impact of lignocellulose pyrolysis on biochar structure in relation to the sorption mechanism of ionizable antibiotics is still poorly understood. In this paper, diverse techniques including thermogravimetric analysis and ¹³C nuclear magnetic resonance were applied to investigate the properties of biochars as affected by the pyrolysis of cellulose and lignin in feedstock. Cellulose-derived biochars possessed more abundant groups than lignin-derived biochars, suggesting the greater preservation of group for cellulose during the carbonization. Higher sorption of sulfamethoxazole (SMX) was also observed by cellulose-derived biochars owing to hydrogen bond interaction. Sorption affinity gradually declined with the conversion aliphatic to aromatic carbon, whereas the enhanced specific surface area (SSA) subsequently promoted SMX sorption as evidenced by increased SSA-N₂ and SSA-CO₂ from 350 to 450 °C. The decreased K_d/SSA-N₂ values with increasing pH values implied a distinct reduction in sorption per unit area, which could be attributed to enhanced electrostatic repulsion. This work elucidated the role of carbon phases from thermal conversion of lignocellulose on the sorption performance for sulfonamide antibiotics, which will be helpful to the structural design of carbonaceous adsorbents for the removal of ionizable antibiotics. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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19 pages, 1346 KiB

Open AccessArticle

Poultry Litter Biochar as a Gentle Soil Amendment in Multi-Contaminated Soil: Quality Evaluation on Nutrient Preservation and Contaminant Immobilization

by Chen-Chi Tsai and Yu-Fang Chang

Agronomy 2022, 12(2), 405; https://doi.org/10.3390/agronomy12020405 - 06 Feb 2022

Cited by 6 | Viewed by 1890

Abstract

Poultry litter biochar (PLB) has great potential for carbon (C) sequestration, which has been confirmed in the previous study. The promising potential of PLB for nutrient preservation and contaminant immobilization, however, has not been well studied. A multi-contaminated soil, mainly contaminated by chrome [...] Read more.

Poultry litter biochar (PLB) has great potential for carbon (C) sequestration, which has been confirmed in the previous study. The promising potential of PLB for nutrient preservation and contaminant immobilization, however, has not been well studied. A multi-contaminated soil, mainly contaminated by chrome (Cr), copper (Cu), nickel (Ni), and zinc (Zn) was selected for this short-term incubation study. The purpose of this study was to evaluate the effects of PLB after incubation on the release of available nutrients (phosphorus, P; potassium, K; calcium, Ca; magnesium, Mg) and on the solubility of Cr, Cu, Ni, and Zn. The results of 56-day incubation indicated that high-temperature pyrolysis PLB (>400 °C) has great potential to raise soil pH, electrical conductivity (EC), and concentrations of P, K, and Mg; however, maintenance of lower Cr and Cu concentrations and a decline in Ni and Zn concentrations were also observed. The solubility of Cr, Cu, and Ni increased with dissolved organic carbon (DOC) increased, suggesting co-mobilization occurred. The solubility of Zn decreased with increased pH, suggesting adsorption by PLB and/or soil. We recommend the use of 5% high temperature pyrolysis PLB (500 and 600 °C) as a gentle soil amendment to achieve C sequestration, provide available nutrients, maintain low available concentrations of Cr/Cu, and reduce Ni/Zn availability. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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15 pages, 2268 KiB

Open AccessFeature PaperArticle

Investigating the Responses of Microbial Communities to Banana Fusarium Wilt in Suppressive and Conducive Soils Based on Soil Particle-Size Differentiation

by Quanzhi Wang, Limin Zhou, Han Jin, Bingcheng Cong, Hua Yang and Shimei Wang

Agronomy 2022, 12(2), 229; https://doi.org/10.3390/agronomy12020229 - 18 Jan 2022

Cited by 6 | Viewed by 1877

Abstract

The microbiota plays a primary role in inhibiting plant pathogens in the soils. However, the correlation between soil particles and local microbial communities has not been fully confirmed. In this study, we contrasted the different assemblages of microbial communities between suppressive and conducive [...] Read more.

The microbiota plays a primary role in inhibiting plant pathogens in the soils. However, the correlation between soil particles and local microbial communities has not been fully confirmed. In this study, we contrasted the different assemblages of microbial communities between suppressive and conducive soils via the differentiation of soil particle-size fractions (PSFs). We further extracted the direct and indirect interactive associations among the soil biotic and abiotic factors by using samples from two continuous banana cropping systems. Notable differences were shown in PSF composition, biological traits (microbial communities and enzyme patterns) and physiochemical parameters between suppressive and conducive soils among the different soil fractions. For example, compared with conducive soils, suppressive soils have higher nutrient contents, fungal abundance and diversity and enzyme activities, and the extent of these differences was explored for fractions of different sizes. Moreover, the microbial taxonomic composition strongly varied between disease-suppressive and disease-conducive soils. For instance, there were significant differences in the relative abundance among key microbiology communities, such as Actinobacteria, Firmicutes, Bacteroidetes, Proteobacteria and Ascomycota, especially for antagonistic microorganisms (i.e., Streptomyces, Pseudomonas, Trichoderma, etc.) across various soil fractions. In addition, structural equation modeling (SEM) showed that the complex associations among soil PSFs, physiochemical parameters and microbial communities were mediated by multiple pathways, which then drive the soil enzyme activities and may further influence the suppressiveness of the soil. These results demonstrate that the resident microbial communities in specific soil particles may play a crucial role in the development of soil suppressiveness against banana Fusarium wilt disease. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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15 pages, 1288 KiB

Open AccessArticle

Remediation of Agricultural Soils with Long-Term Contamination of Arsenic and Copper in Two Chilean Mediterranean Areas

by Pedro Mondaca, Patricio Valenzuela, Nicole Roldán, Waldo Quiroz, Mónika Valdenegro and Juan L. Celis-Diez

Agronomy 2022, 12(1), 221; https://doi.org/10.3390/agronomy12010221 - 17 Jan 2022

Cited by 7 | Viewed by 2206

Abstract

Soil amendments may decrease trace element accumulation in vegetables, improving food security and allowing the recovery of contaminated farmlands. Despite some promising results in the laboratory, validation of soil amendments in field conditions are scarce, especially in aerobic soils. Here, we assessed the [...] Read more.

Soil amendments may decrease trace element accumulation in vegetables, improving food security and allowing the recovery of contaminated farmlands. Despite some promising results in the laboratory, validation of soil amendments in field conditions are scarce, especially in aerobic soils. Here, we assessed the effect of different potential soil amendments on arsenic (As) accumulation in lettuces. Then, we compared them in terms of food security and the associated investment (efficacy and efficiency, respectively). We also hypothesized that the soil amendments do not lead to side effects, such as yield decrease, phytotoxicity of Cu, or undesired changes in soil properties. Thereby, we assessed lettuces grown on untreated contaminated soils (C+), treated contaminated soils, and untreated uncontaminated soils (C−) in two contrasting soil types (sandy and loamy soils). The treated contaminated soils consisted of multiple soil amendments. Soil amendments were: diammonium phosphate (DP), iron sulfate (IS), ferrous phosphate (FP), calcium peroxide (CP), and organic matter (OM). We found that phosphate amendments (DP and FP) reduced the As in edible tissues of lettuce in both areas, while CP only reduced As accumulation in the sandy soils area. The As intake through lettuces grown on these amended soils was about 30% lower than on the unamended ones. Cu concentrations in lettuces above 25 mg kg⁻¹ grown in contaminated soils without reducing growth were found, a result that differed from non-field studies. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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9 pages, 1921 KiB

Open AccessArticle

Applicability of Near Infrared Reflectance Spectroscopy to Predict Amylose Contents of Single-Grain Maize

by Qing Dong, Qianqian Xu, Jiandong Wu, Beijiu Cheng and Haiyang Jiang

Agronomy 2021, 11(12), 2463; https://doi.org/10.3390/agronomy11122463 - 03 Dec 2021

Cited by 2 | Viewed by 1874

Abstract

Near infrared reflectance spectroscopy (NIRS) and reference data were used to determine the amylose contents of single maize seeds to enable rapid, effective selection of individual seeds with desired traits. To predict the amylose contents of a single seed, a total of 1069 [...] Read more.

Near infrared reflectance spectroscopy (NIRS) and reference data were used to determine the amylose contents of single maize seeds to enable rapid, effective selection of individual seeds with desired traits. To predict the amylose contents of a single seed, a total of 1069 (865 as calibration set, 204 as validation set) single seeds representing 120 maize varieties were analyzed using chemical methods and performed calibration and external validation of the 150 single seeds set in parallel. Compared to various spectral pretreatments, the regression of partial least squares (PLS) with mathematical treatment of Harmonization showed the final optimization. The single-seed amylose contents showed the root mean square error of calibration (RMSEC) of 2.899, coefficient of determination for calibration (R²) of 0.902, and root mean square error of validation (RMSEV) of 2.948. In external validations, the coefficient of determination in cross-validation (r²), root mean square error of the prediction (RMSEP) and ratio of the standard deviation to SEP (RPD) were 0.892, 2.975 and 3.086 in the range of 20–30%, respectively. Therefore, NIRS will be helpful to breeders for determining the amylose contents of single-grain maize. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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20 pages, 3458 KiB

Open AccessEditor’s ChoiceArticle

Elevated Fe and Mn Concentrations in Groundwater in the Songnen Plain, Northeast China, and the Factors and Mechanisms Involved

by Yuanzheng Zhai, Xinyi Cao, Xuelian Xia, Bin Wang, Yanguo Teng and Xiao Li

Agronomy 2021, 11(12), 2392; https://doi.org/10.3390/agronomy11122392 - 24 Nov 2021

Cited by 27 | Viewed by 2458

Abstract

Groundwater is an essential source of drinking and irrigation water. However, elevated Fe and Mn concentrations in groundwater have been found in recent decades, which can adversely affect human health and decrease crop quality and yields. The roles of hydrogeochemical changes and groundwater [...] Read more.

Groundwater is an essential source of drinking and irrigation water. However, elevated Fe and Mn concentrations in groundwater have been found in recent decades, which can adversely affect human health and decrease crop quality and yields. The roles of hydrogeochemical changes and groundwater pollution (exogenous reductive material inputs) in this have not been studied adequately. We determined the distribution of Fe and Mn concentrations in groundwater in the Songnen Plain, northeast China, which is known for elevated Fe and Mn concentrations, and investigated the factors and mechanisms involved in causing the elevated concentrations. Chemical and statistical analyses indicated that the Fe and Mn concentrations in groundwater significantly correlated with climate parameters (precipitation and temperature), surface features (altitude, distance from a river, soil type, soil texture, and land use type) and hydrogeochemical characteristics (chemical oxygen demand and NH₄⁺, NO₃⁻, and P concentrations). In particular, the Fe and Mn concentrations in groundwater are higher in areas containing paddy fields and water bodies than other land use type areas. Areas with groundwater containing ultra-high Fe and Mn concentrations have almost all of the favorable factors. The main reasons for the elevated Fe and Mn concentrations in groundwater in the study area are the Fe/Mn mineral-rich strata and soil with abundant organic matter acting as sources of Fe and Mn to the groundwater and the reductive environment in the lower terrain and areas containing water bodies favoring Fe and Mn dissolution in the groundwater. Inputs of pollutants from agricultural activities have caused the Fe and Mn concentrations in groundwater to increase. Future studies should be performed to study interactions between pollutants from agricultural activities and Fe and Mn in groundwater and develop environmental management strategies for preventing future increases in Fe and Mn concentrations and promoting sustainable development of agriculture. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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16 pages, 3705 KiB

Open AccessArticle

Application of Cogon Grass (Imperata cylindrica) as Biosorbent in Diesel-Filter System for Oil Spill Removal

by Farah Eryssa Khalid, Siti Aqlima Ahmad, Nur Nadhirah Zakaria, Noor Azmi Shaharuddin, Suriana Sabri, Alyza Azzura Azmi, Khalilah Abdul Khalil, Gayathiri Verasoundarapandian, Claudio Gomez-Fuentes and Azham Zulkharnain

Agronomy 2021, 11(11), 2273; https://doi.org/10.3390/agronomy11112273 - 10 Nov 2021

Cited by 7 | Viewed by 10368

Abstract

Imperata cylindrica, often known as cogon grass, is a low-cost and useful sorbent for absorbing oil and optimising processes. The effects of temperature, time, packing density and oil concentration on oil absorption efficiency were investigated and optimised utilising one-factor-at-a-time (OFAT) and response [...] Read more.

Imperata cylindrica, often known as cogon grass, is a low-cost and useful sorbent for absorbing oil and optimising processes. The effects of temperature, time, packing density and oil concentration on oil absorption efficiency were investigated and optimised utilising one-factor-at-a-time (OFAT) and response surface methodology (RSM) approaches. Temperature and oil concentration are two important variables in the oil absorption process. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis were used to characterise cogon grass. After treatment and oil absorption, the FTIR method indicated new formation and deformation of functional groups, while SEM revealed changes in the surface and texture of cogon grass, including a roughened and jagged surface. Validation of the RSM model yielded 93.54% efficiency with 22.45 mL oil absorbed at 128 °C temperature and 36 (v/v)% oil concentration while keeping packing density and time constant at 30 min and 0.20 g/cm³, respectively. This study may provide an insight into the usefulness of a statistical approach to maximise the oil absorption of cogon grass as an oil sorbent. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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14 pages, 1938 KiB

Open AccessArticle

Responses of Soil Cadmium Desorption under Different Saline Environments and Its Controlling Factors

by Nengzhan Zheng, Weifeng Yue, Jin Wu, Kaixuan Hou, Lijun Wu, Mengshen Guo and Yanguo Teng

Agronomy 2021, 11(11), 2175; https://doi.org/10.3390/agronomy11112175 - 28 Oct 2021

Cited by 5 | Viewed by 1733

Abstract

Heavy metal pollution of soil restricts the sustainable use of land and poses risks to human health throughout the world. Changes in the physicochemical properties of soil may increase the mobility of heavy metals in the soil ecosystem and lead to groundwater pollution. [...] Read more.

Heavy metal pollution of soil restricts the sustainable use of land and poses risks to human health throughout the world. Changes in the physicochemical properties of soil may increase the mobility of heavy metals in the soil ecosystem and lead to groundwater pollution. In this study, the effects of different salt solutions (NaCl, CaCl₂, NaNO₃, MgCl₂, Na₂SO₄, and mixed salts) on the release of Cd from soil were investigated by batch desorption tests and the Freundlich isothermal sorption model. Increased concentrations of the salts, except for NaNO₃, significantly promoted Cd release (R² > 0.9, p < 0.01). Under the salt stress, Cd release from the test soils was promoted more by CaCl₂ and MgCl₂ than by the other salts, and the average desorption rates of eight soil samples at 3.5% salt concentration were 11.15% and 10.80%, respectively, which were much higher than those of NaCl (4.05%), Na₂SO₄ (0.41%), and NaNO₃ (0.33%). Ca²⁺ and Mg²⁺ showed better ion exchange capacity than Na⁺ to promote Cd release; for anions, Cl⁻ formed hydrophilic Cd chloride complexes with Cd in soil. In addition, principal component analysis results revealed that Cd release was mainly influenced by soil texture, cation exchange capacity, and iron–manganese oxide content of the soil. The Cd release level for different soil samples was most closely related to the proportion of fine particles in the soil. The higher the clay content was, the higher the Cd desorption rate. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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14 pages, 2136 KiB

Open AccessArticle

Alleviating Soil Acidification and Increasing the Organic Carbon Pool by Long-Term Organic Fertilizer on Tobacco Planting Soil

by Peigang Dai, Ping Cong, Peng Wang, Jianxin Dong, Zhaorong Dong and Wenjing Song

Agronomy 2021, 11(11), 2135; https://doi.org/10.3390/agronomy11112135 - 25 Oct 2021

Cited by 17 | Viewed by 2868

Abstract

Long term tobacco planting leads to soil acidification. A ten-year experiment with various fertilization treatments (no fertilization (CK), chemical fertilizer (CF), organic-inorganic compound fertilizer (OCF), and organic fertilizer (OF)) was carried out between 2010 and 2020 in a continuous cropping system of Nicotiana [...] Read more.

Long term tobacco planting leads to soil acidification. A ten-year experiment with various fertilization treatments (no fertilization (CK), chemical fertilizer (CF), organic-inorganic compound fertilizer (OCF), and organic fertilizer (OF)) was carried out between 2010 and 2020 in a continuous cropping system of Nicotiana tabacum in the brown soil of eastern China, to assess the effects of organic fertilizer on the improvement of tobacco planting soil acidification. The results indicated that treatments OCF and OF reduced the soil exchangeable acid content, of which the exchangeable aluminum showed the largest reduction by 51.28% with the OF treatment. In contrast, treatment CF showed more significant increases in exchangeable aluminum (Al) and Al saturation, and also apparently increased soil NO₃⁻-N, NH₄⁺-N and nitrification potential (NP) than other treatments. Treatments of OCF and OF significantly increased the total amount of exchangeable base (EBC) by 37.19% and 42.00% compared with CF, respectively. Redundancy analysis (RDA) showed that NP, NH₄⁺-N, and NO₃⁻-N were the important factors indicating soil acidification, while EBC and exchangeable K were the significant factors restricting soil acidification. Inevitably, OCF could improve the soil organic carbon pool and labile organic carbon pool. The structural equation model (SEM) showed that OCF treatment increased the soil organic carbon pool mainly by inhibiting soil nitrification and reducing the content of exchangeable Al. In conclusion, both OF and OCF treatments were effective methods to alleviate tobacco planting soil acidification, however OCF had more advantages in improving soil organic carbon pool. Full article

(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability)

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