关键词：
Bamboo-derived biochar;Dicyandiamide;Urease kinetics;Mineral nitrogen;Microbial community diversity
摘要：
Soil urease kinetics reflects the affinity and catalytic reaction rate of urease. However, an incomplete understanding on soil urease kinetic hampered the optimisation of soil N management practices for agricultural and forestry ecosystems. In the present study, different soils from farmland and forest land were subjected to the following four treatments: (1) blank control (CK), (2) bamboo-derived biochar application (BC), (3) DCD application (DC), and (4) combined application of bamboo-derived biochar and DCD (CBAD). In the forest soil, the urease kinetic half-saturation constant ( K m ) values decreased significantly by 28 %, 73 % and 45 % in the BC, DC and CBAD treatments, respectively. Similarly, in the agricultural soil, these values decreased by 46 %, 29 %, and 46 %, respectively. However, no significant difference in urease decomposition rates at saturated substrate concentrations ( V max ) was observed among the four treatments. The contribution percentages of soil abiotic and biotic (the composition of bacterial and fungal community) properties to the variability in K m were 58.6 % and 41.4 %, respectively. Biochar and DCD application improved the catalytic potential of urease in the agricultural and forest soils, which would not be conducive to the retention of nitrogen in soils. The increases in the catalytic potential of urease were associated with the increased content of mineral N and fungal community diversity under the application of biochar or DCD. Abiotic factors outweighed the microbial community composition in altering urease kinetics in various soils. These findings highlighted the necessity of nitrogen-fixing measures in soils amended with biochar or DCD and advanced our comprehension of how abiotic and biotic factors influence the urease kinetics in agricultural and forest soils.
Soil urease kinetics reflects the affinity and catalytic reaction rate of urease. However, an incomplete understanding on soil urease kinetic hampered the optimisation of soil N management practices for agricultural and forestry ecosystems. In the present study, different soils from farmland and forest land were subjected to the following four treatments: (1) blank control (CK), (2) bamboo-derived biochar application (BC), (3) DCD application (DC), and (4) combined application of bamboo-derived biochar and DCD (CBAD). In the forest soil, the urease kinetic half-saturation constant ( K m ) values decreased significantly by 28 %, 73 % and 45 % in the BC, DC and CBAD treatments, respectively. Similarly, in the agricultural soil, these values decreased by 46 %, 29 %, and 46 %, respectively. However, no significant difference in urease decomposition rates at saturated substrate concentrations ( V max ) was observed among the four treatments. The contribution percentages of soil abiotic and biotic (the composition of bacterial and fungal community) properties to the variability in K m were 58.6 % and 41.4 %, respectively. Biochar and DCD application improved the catalytic potential of urease in the agricultural and forest soils, which would not be conducive to the retention of nitrogen in soils. The increases in the catalytic potential of urease were associated with the increased content of mineral N and fungal community diversity under the application of biochar or DCD. Abiotic factors outweighed the microbial community composition in altering urease kinetics in various soils. These findings highlighted the necessity of nitrogen-fixing measures in soils amended with biochar or DCD and advanced our comprehension of how abiotic and biotic factors influence the urease kinetics in agricultural and forest soils.
摘要：
Abundant evidences have demonstrated that below-ground feedback mediated by crop diversification is essential for enhancing crop productivity. However, there is a knowledge gap about the mechanism underlying intercropping-driven productivity gain from the perspective of interactive scenarios of root traits and arbuscular mycorrhizal fungi (AMF). Herein, a ten-year field experiment was employed to reveal the differences of rhizosphere AMF community and root functional traits between maize monocropping and intercropping systems (maize-peanut, maize-soybean, maize-gingelly, and maize-sweet potato), as well as their relationships with maize productivity. AMF community traits were identified by high-throughput sequencing combined with bioinformatics and ecological analysis. Plant biomass, carbon (C) and nutrient content and accumulation were considered as productivity indicators, and root activity and morphology were considered as root functional traits. Compared with monocropping system, intercropping systems showed higher maize biomass, C accumulation and nutrient uptake (P < 0.05), and the intercropping advantage varied at different growth stages. Monocropping and intercropping systems showed a significant difference in maize root activity and morphology. AMF colonization significantly increased in all systems as maize developed, with the maize-peanut and maize-soybean consistently keeping higher colonization than other systems. The AMF communities of all systems except maize-gingelly were with greater force governed by deterministic assembly processes (MST < 50 %), in which monocropping system presented the lowest stochasticity ratio. AMF community composition in maize-soybean system was most deterministically driven and most diffusion-limited in neutral model. Compared with monocropping system, AMF community network showed a higher robustness in intercropping systems. And the ASVs of AMF community enriched by intercropping systems mainly belonged to genus Paraglomus, Glomus, and Claroideoglomus. The colonization, Shannon index, community composition, and core taxa (Glomus) of rhizosphere AMF influenced plant biomass and C and nutrient accumulation directly or indirectly by regulating root activity and morphology. Root activity also affected these maize productivity indicators directly or indirectly by regulating AMF community composition and core taxa (Claroideoglomus and Paraglomus). This work highlights the benefits of rhizosphere AMF in productivity gain of intercropping systems, and meanwhile, underscores the importance of AMF and root interactions in crop production.
Abundant evidences have demonstrated that below-ground feedback mediated by crop diversification is essential for enhancing crop productivity. However, there is a knowledge gap about the mechanism underlying intercropping-driven productivity gain from the perspective of interactive scenarios of root traits and arbuscular mycorrhizal fungi (AMF). Herein, a ten-year field experiment was employed to reveal the differences of rhizosphere AMF community and root functional traits between maize monocropping and intercropping systems (maize-peanut, maize-soybean, maize-gingelly, and maize-sweet potato), as well as their relationships with maize productivity. AMF community traits were identified by high-throughput sequencing combined with bioinformatics and ecological analysis. Plant biomass, carbon (C) and nutrient content and accumulation were considered as productivity indicators, and root activity and morphology were considered as root functional traits. Compared with monocropping system, intercropping systems showed higher maize biomass, C accumulation and nutrient uptake (P < 0.05), and the intercropping advantage varied at different growth stages. Monocropping and intercropping systems showed a significant difference in maize root activity and morphology. AMF colonization significantly increased in all systems as maize developed, with the maize-peanut and maize-soybean consistently keeping higher colonization than other systems. The AMF communities of all systems except maize-gingelly were with greater force governed by deterministic assembly processes (MST < 50 %), in which monocropping system presented the lowest stochasticity ratio. AMF community composition in maize-soybean system was most deterministically driven and most diffusion-limited in neutral model. Compared with monocropping system, AMF community network showed a higher robustness in intercropping systems. And the ASVs of AMF community enriched by intercropping systems mainly belonged to genus Paraglomus, Glomus, and Claroideoglomus. The colonization, Shannon index, community composition, and core taxa (Glomus) of rhizosphere AMF influenced plant biomass and C and nutrient accumulation directly or indirectly by regulating root activity and morphology. Root activity also affected these maize productivity indicators directly or indirectly by regulating AMF community composition and core taxa (Claroideoglomus and Paraglomus). This work highlights the benefits of rhizosphere AMF in productivity gain of intercropping systems, and meanwhile, underscores the importance of AMF and root interactions in crop production.
期刊：
Separation and Purification Technology,2025年361:131592 ISSN：1383-5866
通讯作者：
Leng, Lijian;Zhan, Hao;Li, HL
作者机构：
[Zheng, Huihui; Peng, Haoyi; Leng, Lijian; Li, HL; Zhan, Hao; Li, Hailong] Cent South Univ, Sch Energy Sci & Engn, Changsha 410083, Peoples R China.;[Xiong, Ting; Leng, Lijian] Xiangjiang Lab, Changsha 410205, Peoples R China.;[Wu, Zhibin; Shen, Tian] Hunan Agr Univ, Coll Resources & Environm, Changsha 410128, Hunan, Peoples R China.;[Xiong, Ting] Hunan Univ Technol & Business, Sch Adv Interdisciplinary Studies, Changsha 410205, Peoples R China.;[Liu, Shengqiang] Aerosp Kaitian Environm Technol Co Ltd, Changsha 410100, Peoples R China.
通讯机构：
[Leng, LJ; Li, HL ; Zhan, H] C;Cent South Univ, Sch Energy Sci & Engn, Changsha 410083, Peoples R China.
关键词：
Cation exchange capacity;Heavy metal removal;Bio-char;Pyrogenic carbon material;Machine learning
摘要：
The application of biochar in heavy metal removal has attracted significant attention due to its characteristics. However, engineering biochar materials through trial-and-error methods is traditionally applied, but it is time-consuming and labor-intensive. Applying machine learning (ML) promises to substantially enhance the efficiency of engineering biochar with desired properties. Here, ML was employed for the first time to predict multiple properties of biochar that are critical to heavy metal adsorption, such as cation exchange capacity (CEC). Previous studies have focused on correlations between the CEC and application performance of biochar, but no study has reported the direct prediction of heavy metal adsorption capacity (qe) from biomass. Therefore, a biomass—production—application hybrid ML model (test R 2 0.996) was constructed by integrating the biomass—production—biochar-properties ML model (test R 2 0.941) and the biochar-properties—application (heavy metal adsorption) ML model (test R 2 0.960). This innovative hybrid model facilitated the screening of biomass feedstock and the optimization of pyrolysis conditions, using only elemental composition data of biomass. With nine biomass feedstocks in the lab, the hybrid ML model effectively provided the optimum solution for producing biochar with the highest q e (e.g., predicted q e of ∼0.60 mmol/g for Cd 2+ ). Finally, the experimental verification of the optimum solution showed that the adsorption capacities of the as-produced optimum biochar were comparable with the hybrid model-predicted ones (validation R 2 0.859), and the adsorption mechanism study echoed the dominant role of cation exchange, showing the great potential of such hybrid ML models to promote the production of designer biochar.
The application of biochar in heavy metal removal has attracted significant attention due to its characteristics. However, engineering biochar materials through trial-and-error methods is traditionally applied, but it is time-consuming and labor-intensive. Applying machine learning (ML) promises to substantially enhance the efficiency of engineering biochar with desired properties. Here, ML was employed for the first time to predict multiple properties of biochar that are critical to heavy metal adsorption, such as cation exchange capacity (CEC). Previous studies have focused on correlations between the CEC and application performance of biochar, but no study has reported the direct prediction of heavy metal adsorption capacity (qe) from biomass. Therefore, a biomass—production—application hybrid ML model (test R 2 0.996) was constructed by integrating the biomass—production—biochar-properties ML model (test R 2 0.941) and the biochar-properties—application (heavy metal adsorption) ML model (test R 2 0.960). This innovative hybrid model facilitated the screening of biomass feedstock and the optimization of pyrolysis conditions, using only elemental composition data of biomass. With nine biomass feedstocks in the lab, the hybrid ML model effectively provided the optimum solution for producing biochar with the highest q e (e.g., predicted q e of ∼0.60 mmol/g for Cd 2+ ). Finally, the experimental verification of the optimum solution showed that the adsorption capacities of the as-produced optimum biochar were comparable with the hybrid model-predicted ones (validation R 2 0.859), and the adsorption mechanism study echoed the dominant role of cation exchange, showing the great potential of such hybrid ML models to promote the production of designer biochar.
摘要：
This study aimed to systematically investigate the effects of low-temperature pyrolysis on the physicochemical properties and their internal connection. This work evaluated the influences of low-temperature pyrolysis on proximate analysis, element composition, stability, and structural features of prepared straw biochar from two feedstocks pyrolyzed at 225 °C to 600 °C. The different indicators, including yield, pH, fixed carbon (FC), volatile matter (VM), ash, C, H, O, N, P, K, Mg, Zn, and stability indexes, all followed exponential function with temperature ( R 2 > 0.82). As the pyrolysis temperature increased from 225 °C to 400 °C, most physicochemical properties of straw biochar demonstrated a rapid change. Additionally, 400°C was a crucial turning point, all biochar physicochemical indicators showed a slowly changing trend at temperatures above 400 °C. Factor and hierarchical clustering analyses yielded identical results. The physicochemical properties can be classified into two groups of intrinsically connected properties: (1) yield, O, H, VM, VM/FC, H/C, and O/C, and (2) N, Zn, Mg, P, K, FC, pH, ash, and C. The quantitative relationships between ash and other properties of the tobacco and rice straw biochar revealed that ash was positively and exponentially associated with pH, FC, C, P, K, Mg, and Zn ( R 2 = 0.73–0.96). Conversely, negative exponential relationships were found with yield, VM, H, O, VM/FC, H/C, and O/C ( R 2 = 0.83–0.96). This work supplies data support for a better understanding of the intrinsic characteristics of straw biochar, especially in scientific preparation and utilization.
This study aimed to systematically investigate the effects of low-temperature pyrolysis on the physicochemical properties and their internal connection. This work evaluated the influences of low-temperature pyrolysis on proximate analysis, element composition, stability, and structural features of prepared straw biochar from two feedstocks pyrolyzed at 225 °C to 600 °C. The different indicators, including yield, pH, fixed carbon (FC), volatile matter (VM), ash, C, H, O, N, P, K, Mg, Zn, and stability indexes, all followed exponential function with temperature ( R 2 > 0.82). As the pyrolysis temperature increased from 225 °C to 400 °C, most physicochemical properties of straw biochar demonstrated a rapid change. Additionally, 400°C was a crucial turning point, all biochar physicochemical indicators showed a slowly changing trend at temperatures above 400 °C. Factor and hierarchical clustering analyses yielded identical results. The physicochemical properties can be classified into two groups of intrinsically connected properties: (1) yield, O, H, VM, VM/FC, H/C, and O/C, and (2) N, Zn, Mg, P, K, FC, pH, ash, and C. The quantitative relationships between ash and other properties of the tobacco and rice straw biochar revealed that ash was positively and exponentially associated with pH, FC, C, P, K, Mg, and Zn ( R 2 = 0.73–0.96). Conversely, negative exponential relationships were found with yield, VM, H, O, VM/FC, H/C, and O/C ( R 2 = 0.83–0.96). This work supplies data support for a better understanding of the intrinsic characteristics of straw biochar, especially in scientific preparation and utilization.
作者：
Yu Dai;Benjamin C. Bostick;Huihui Du;Xueyuan Gu;Guopei Huang;...
期刊：
Geochimica et Cosmochimica Acta,2025年 ISSN：0016-7037
通讯作者：
Jing Sun
作者机构：
[Guopei Huang; Shirong Liu; Yizhang Liu; Zengping Ning; Jing Sun] State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;School of Public Health, the Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang 550025, China;[Benjamin C. Bostick] Lamont-Doherty Earth Observatory, PO Box 1000, 61 Route 9W, Palisades, NY 10964, United States;[Huihui Du] College of Resources and Environment, Hunan Agricultural University, 410127 Changsha, China;[Xueyuan Gu] School of Environment, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Nanjing 210023, China
通讯机构：
[Jing Sun] S;State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
摘要：
A high specific surface area (SSA) typically signifies a superior adsorption capacity. Nevertheless, minerals with high SSAs tend to possess tiny pores that may not be accessible to relatively large (poly)oxyanionic metals. Herein, we assessed the adsorption of (poly)oxyanionic metals on 2-line and 6-line ferrihydrite and goethite with distinct SSAs and pore geometries. SSA was estimated by BET isotherm using N 2 , while pore geometry was measured by N 2 adsorption isotherms and positron annihilation lifetime spectroscopy. Tungstate and its polymers were chosen as representative (poly)oxyanions. Adsorption experiments were performed with constant mineral surface area, but different contact time, pH, and tungsten concentrations. Unexpectedly, the Langmuir adsorption capacities per unit surface area on 6-line ferrihydrite and goethite were 2–6 and 3–11 times as high as those on 2-line ferrihydrite, respectively. Adsorption on 2-line ferrihydrite was also severely kinetically limited. The varying rates and magnitudes of adsorption were attributed to distinct mineral pore widths: (poly)tungstates could hardly fit within the abundant tiny pores in 2-line ferrihydrite formed by voids between the primary particles/aggregates, but could enter the larger pores in 6-line ferrihydrite and goethite. Consequently, significant decreases of mineral microporosity (<2 nm) were observed following (poly)tungstate adsorption. Tungstate and polytungstate with different hydrated ion radii exhibited similar adsorption behavior, most likely due to the formation of adsorbed polytungstate directly on mineral surface. Our data demonstrate that mineral pore geometry controls the solid-solution partitioning of (poly)oxyanionic metals, which is crucial to comprehend their environmental fate and to mitigate their contamination.
A high specific surface area (SSA) typically signifies a superior adsorption capacity. Nevertheless, minerals with high SSAs tend to possess tiny pores that may not be accessible to relatively large (poly)oxyanionic metals. Herein, we assessed the adsorption of (poly)oxyanionic metals on 2-line and 6-line ferrihydrite and goethite with distinct SSAs and pore geometries. SSA was estimated by BET isotherm using N 2 , while pore geometry was measured by N 2 adsorption isotherms and positron annihilation lifetime spectroscopy. Tungstate and its polymers were chosen as representative (poly)oxyanions. Adsorption experiments were performed with constant mineral surface area, but different contact time, pH, and tungsten concentrations. Unexpectedly, the Langmuir adsorption capacities per unit surface area on 6-line ferrihydrite and goethite were 2–6 and 3–11 times as high as those on 2-line ferrihydrite, respectively. Adsorption on 2-line ferrihydrite was also severely kinetically limited. The varying rates and magnitudes of adsorption were attributed to distinct mineral pore widths: (poly)tungstates could hardly fit within the abundant tiny pores in 2-line ferrihydrite formed by voids between the primary particles/aggregates, but could enter the larger pores in 6-line ferrihydrite and goethite. Consequently, significant decreases of mineral microporosity (<2 nm) were observed following (poly)tungstate adsorption. Tungstate and polytungstate with different hydrated ion radii exhibited similar adsorption behavior, most likely due to the formation of adsorbed polytungstate directly on mineral surface. Our data demonstrate that mineral pore geometry controls the solid-solution partitioning of (poly)oxyanionic metals, which is crucial to comprehend their environmental fate and to mitigate their contamination.
摘要：
Soil is the basis of bamboo growth and quality formation of bamboo shoots and has an important contribution to the sustainable development of agriculture. To this end, We studied the soil properties and microbial communities of Dendrocalamus brandisii by collecting twenty-one soil samples from its seven typical geographic provenances in Yunnan Province, China. Bacterial 16S rRNA gene amplicons were used to detect soil bacteria and predict bacterial functions using Tax4Fun. The results indicated that the soil bacterial diversity indices (ACE, Chao1, Simpson, and Shannon) were significantly different among different geographical provenances. The dominant bacterial groups at the phylum level in all seven regions were Proteobacteria (19.78 similar to 29.06%), Actinobacteria (13.53 similar to 30.01%), Chloroflexi (8.03 similar to 31.47%), and Acidobacteria (7.12 similar to 19.17%), with markedly different constitution proportions. Total phosphorus, available potassium, and pH were the main environmental factors affecting soil bacterial communities. There were significant differences in the secondary metabolic pathways and phenotypes of soil bacterial functions, exhibiting a diversity of functions. The geographical variables of the soil bacterial community in D. brandisii varied with spatial scales. Environmental factors such as available potassium (AK), pH, and total nitrogen (TN) have an impact on soil bacterial communities.
摘要：
Intercropping leads to different plant roots directly influencing belowground processes and has gained interest for its promotion of increased crop yields and resource utilization. However, the precise mechanisms through which the interactions between rhizosphere metabolites and the microbiome contribute to plant production remain ambiguous, thus impeding the understanding of the yield-enhancing advantages of intercropping. This study conducted field experiments (initiated in 2013) and pot experiments, coupled with multi-omics analysis, to investigate plant-metabolite-microbiome interactions in the rhizosphere of maize. Field-based data revealed significant differences in metabolite and microbiome profiles between the rhizosphere soils of maize monoculture and intercropping. In particular, intercropping soils exhibited higher microbial diversity and metabolite chemodiversity. The chemodiversity and composition of rhizosphere metabolites were significantly related to the diversity, community composition, and network complexity of soil microbiomes, and this relationship further impacted plant nutrient uptake. Pot-based findings demonstrated that the exogenous application of a metabolic mixture comprising key components enriched by intercropping (soyasapogenol B, 6-hydroxynicotinic acid, lycorine, shikimic acid, and phosphocreatine) significantly enhanced root activity, nutrient content, and biomass of maize in natural soil, but not in sterilized soil. Overall, this study emphasized the significance of rhizosphere metabolite-microbe interactions in enhancing yields in intercropping systems. It can provide new insights into rhizosphere controls within intensive agroecosystems, aiming to enhance crop production and ecosystem services.
期刊：
Global Change Biology,2024年30(2):e17158- ISSN：1354-1013
通讯作者：
Wang, JJ
作者机构：
[Wang, Jianjun; Wen, Shuailong; Jiang, Shuyu; Han, Lei; Hu, Ang; Zhong, Jicheng] Chinese Acad Sci, Nanjing Inst Geog & Limnol, Key Lab Lake & Watershed Sci Water Secur, Nanjing, Peoples R China.;[Jiang, Shuyu] Nanjing Normal Univ, Coll Life Sci, Nanjing, Peoples R China.;[Han, Lei] Hunan Agr Univ, Coll Resources & Environm, Changsha, Peoples R China.;[Jang, Kyoung-Soon] Korea Basic Sci Inst, Biochem Anal Team, Cheongju, South Korea.;[Tanentzap, Andrew J.] Univ Cambridge, Dept Plant Sci, Cambridge, England.
通讯机构：
[Wang, JJ ] C;Chinese Acad Sci, Nanjing Inst Geog & Limnol, Key Lab Lake & Watershed Sci Water Secur, Nanjing, Peoples R China.
关键词：
carbon quality temperature hypothesis;carbon-climate feedback;chemodiversity;functional traits;geography;global warming;greenhouse gas;lake ecosystems
摘要：
The mean value of temperature sensitivity of organic carbon decomposition in lake sediments is 1.78 ± 0.62. The quantity of sediment organic carbon determines the absolute rate of decomposition, while the quality of organic carbon determines the sensitivity of decomposition to warming. At both molecular and compositional levels, functional traits of DOM revealed the positive correlation between Q10 and biochemical recalcitrance, thus supporting the carbon quality temperature hypothesis. Abstract Organic carbon decomposition in lake sediments contributes substantially to the global carbon cycle and is strongly affected by temperature. However, the magnitude of temperature sensitivity (Q10) of decomposition and the underlying factors remain unclear at the continental scale. Carbon quality temperature (CQT) hypothesis asserts that less reactive and more recalcitrant molecules tend to have higher temperature sensitivities, but its support is challenged by complex composition of organic matter and environmental constraints. Here, we quantified Q10 of the sediments across 50 freshwater ecosystems along a 3500 km north–south transect, and characterized the quality of sediment dissolved organic carbon with chemodiversity reflected in molecular richness, functional traits (i.e., molecular weight, bioavailability, etc.) and composition. We further included classic environmental variables, such as climatic, physicochemical and microbial factors, to explore how Q10 is constrained by these factors or carbon quality. We found that Q10 varied greatly across lakes, with the mean value of 1.78 ± 0.62, but showed nonsignificant latitudinal pattern. Q10 was primarily predicted by chemodiversity and showed an increasing trend with the biochemical recalcitrance indicated by traits such as aromaticity and standard Gibb's Free Energy at both molecular and compositional levels. This suggests that carbon quality is the crucial determinant of Q10 in lakes, supporting the CQT hypothesis. Moreover, Q10 decreased linearly with the increase of molecular richness, implying that the resistance of decomposition to warming is associated with higher molecular diversity. Compared with the structural equation model containing only environmental variables, inclusion of chemodiversity increased 32.8% of the explained variation in Q10, and chemodiversity was the only driver showing direct effects. Collectively, this study illustrates the importance of chemodiversity in shaping the pattern of Q10, and has significant implications for accurately predicting the carbon turnover in lake ecosystems in the context of global warming.
摘要：
In order to explore the response mechanism of Passiflora edulis Sims to drought stress, the changes in morphological and physiological traits of Passiflora edulis Sims under different drought conditions were studied. A total of 7 germplasm resources of Passiflora edulis Sims were selected and tested under drought stress by the pot culture method under 4 treatment levels: 75%-80% (Control, CK) of maximum field water capacity, 55%-60% (Light Drought, LD) of maximum field water capacity, i.e., mild drought, 40%-45% (Moderate Drought, MD) of maximum field water capacity, i.e., moderate drought and 30%-35% (Severe Drought, SD) of maximum field water capacity, i.e., severe drought. On the 40th day of drought treatment, 13 indices, including seedling growth morphology, physiology, and biochemistry, were measured. The results showed that under drought stress, the height and ground diameter of P. edulis Sims gradually decreased with increasing drought stress, and there were significant differences in seedling height and ground diameter among the treatments. Drought stress significantly inhibited the growth of seven P. edulis Sims varieties. The contents of soluble sugar (SS), soluble protein (SP), proline (Pro), and other substances in P. edulis Sims basically increased with increasing drought stress. With the aggravation of drought stress, the malondialdehyde (MDA) content of P. edulis Sims tended to increase to different degrees, the superoxide dismutase (SOD) activity and peroxidase (POD) activity both tended to increase at first and then decrease, and the change in catalase (CAT) activity mostly showed a gradual increasing trend. The contents of endogenous hormones in P. edulis Sims significantly differed under different degrees of drought stress. With the aggravation of drought stress, the abscisic acid (ABA) content of P. edulis Sims tended to increase, whereas the contents of gibberellin (GA), indoleacetic acid (IAA), and zeatin nucleoside (ZR) exhibited a downward trend. A comprehensive evaluation of the drought resistance of seven P. edulis Sims varieties was conducted based on the principal component analysis method, and the results showed that the drought resistance decreased in the order XH-BL > XH-TWZ > TN1 > GH1 > ZJ-MT > LP-LZ > DH-JW.
摘要：
Biological nitrogen fixation and nitrification inhibitor applications contribute to improving soil nitrogen (N) availability, however, free-living N fixation affected by nitrification inhibitors has not been effectively evaluated in soils under different weed management methods. In this study, the effects of the nitrification inhibitors dicyandiamide (DCD) and 3, 4-dimethylpyrazole phosphate (DMPP) on the nitrogenase, nifH gene，and diazotrophic communities in soils under different weed management methods (AMB, weeds growth without mowing or glyphosate spraying; GS, glyphosate spraying; MSG, mowing and removing weeds and glyphosate spraying; and WM, mowing aboveground weeds) were investigated. Compared to the control counterparts, the DCD application decreased soil nitrogenase activity and nifH gene abundance by 4.5% and 37.9%, respectively, under the GS management method, and the DMPP application reduced soil nitrogenase activity by 20.4% and reduced the nifH gene abundance by 83.4% under the MSG management method. The application of nitrification inhibitors significantly elevated soil NH(4)(+)-N contents but decreased NO(3)(-)-N contents, which had adverse impacts on soil nifH gene abundance and nitrogenase activity. The nifH gene abundances were also negatively impacted by dissolved organic N and Geobacter but were positively affected by available phosphorus and diazotrophic community structures. Nitrification inhibitors significantly inhibited Methylocella but stimulated Rhizobiales and affected soil diazotrophic communities. The nitrification inhibitors DCD and DMPP significantly altered soil diazotrophic community structures, but weed management outweighed nitrification inhibitors in reshaping soil diazotrophic community structures. The non-targeted effects of the nitrification inhibitors DMPP and DCD on soil free-living N fixation were substantially influenced by the weed management methods.
摘要：
【目的】按土壤剖面发生层分析水稻土有机碳剖面分布特征及其影响因素。【方法】通过测定湖南省58个水稻土剖面各发生层土壤有机碳含量,分析水稻土剖面有机碳分布特征,并利用地理探测器解析水稻土有机碳含量空间分异的影响因素。【结果...展开更多 【目的】按土壤剖面发生层分析水稻土有机碳剖面分布特征及其影响因素。【方法】通过测定湖南省58个水稻土剖面各发生层土壤有机碳含量,分析水稻土剖面有机碳分布特征,并利用地理探测器解析水稻土有机碳含量空间分异的影响因素。【结果】①湖南省水稻土剖面土壤有机碳平均含量为9.30 g kg−1,其在发生层上的分布表现为耕作层(22.94 g kg−1)>犁底层(15.09 g kg−1)>底土层(6.93 g kg−1)。②不同成土母质发育的土壤中,石灰岩风化物发育的水稻土发生层有机碳含量最大;不同质地的土壤中,水稻土各类发生层有机碳含量整体上表现为随粉粒含量的增加而增大。③各发生层有机碳空间分布均呈现西南高,东北低的格局。④地理探测器结果显示,容重对各发生层水稻土有机碳含量空间分异解释程度最高,且与其他因子交互之后解释力显著增强。【结论】湖南省水稻土有机碳含量在不同剖面发生层存在显著性差异,其空间分布是由多因子交互作用形成的,容重对各发生层有机碳解释力最高。收起
摘要：
Biochar and organic fertilizer are widely supported to maintain crop production and sustainable development of agroecosystems. However, it is unclear how biochar and organic fertilizer alone or in combination regulate soil functional microbiomes and their relationships to ecosystem multifunctionality (EMF). Herein, a long-term (started in 2013) field experiment, containing five fertilization treatments, was employed to explore the effects of biochar and organic fertilizer applications on the EMF (based on 18 functional indicators of crop productivity, soil nutrient supply, element cycling, and microbial biomass) and the functional microbiomes of bulk soil and rhizosphere soil [normalizing the abundances of 64 genes related to carbon (C), nitrogen (N), phosphorus (P), and sulphur (S) cycles]. Compared with single-chemical fertilization, biochar and organic fertilizer inputs significantly enhanced most ecosystem-single functions and, in particular, the EMF significantly increased by 18.7-30.1%; biochar and organic fertilizer applications significantly increased the abundances of soil microbial functional taxa related to C-N-P-S cycles to varying degree. The combined application of biochar and organic fertilizer showed a better improvement in these indicators compared to using them individually. Most functional microbial populations in the soil, especially the taxa involved in C degradation, nitrification, nitrate-reduction, organic P mineralization, and S cycling showed significantly positive associations with the EMF at different threshold levels, which ultimately was regulated by soil pH and nutrient availability. These results highlight the strong links between soil microbiomes and agroecosystem functions, as well as providing scientific support for inclusion of biochar in agricultural production and services with organic amendments. 8-year field evidence revealed impacts of biochar and pig manure on soil functional microbiome and ecosystem functions.Biochar and pig manure inputs notably enhanced most ecosystem-single functions and the EMF increased by 18.7-30.1%.Biochar and pig manure inputs notably enriched soil functional microbes related to C-N-P-S cycles to varying degree.Increase in EMF was related to microbe-driven soil processes such as C degradation, nitrification, and Po mineralization.Inclusion of biochar in crop production with organic amendments could enhance agro-ecosystem functions and services.
摘要：
Biological soil crusts (BSCs) widely exists in mudflat environment, which is known to be efficient in capturing heavy metals from aqueous solutions; However, their ability to adsorb cadmium (Cd(II)) is limited due to low capacity and selectivity. To address this limitation, manganese ethylenediamine phosphates (MEPs) nanomaterial were incorporated into the BSCs to enhance Cd(II) uptake. The MEPs nanomaterials attached to BSC significantly improved the adsorption capacity, rate, and selection for Cd(II). The adsorption kinetics of Cd(II) by BSCs and BSCs-MEPs was well described by a pseudo-second-order model, with BSCs-MEPs exhibiting a much higher adsorption capacity for Cd(II) (77.00 mg/g) compared to BSCs (55.44 mg/g). The Cd(II) removal by BSCs-MEPs has been accelerated to 2 stages, in which the film diffusion/intraparticle diffusion/chemical reaction participated in the 1st stage. And another stage was dynamic equilibrium process. The adsorption isotherm of BSCs-MEPs demonstrated superior performance for Cd(II) compared to BSCs across a pH range from 2 to 9. Most importantly, even in the presence of high concentration of Na+ or Ca2+ ions, BSCs-MEPs exhibited preferential adsorption for Cd(II), a result not observed with BSCs alone. Analysis of X-ray photoelectron spectroscopy spectra demonstrated that functional groups (-NH2/-COOH/-OH) played an important role in Cd(II) adsorption, while the MEPs attach to BSCs leading to the -NH3+ deprotonation, thus enhanced the BSCs' affinity toward Cd(II). Furthermore, molecular dynamics simulation clearly showed that diffusion coefficients (D) of Cd(II) were much higher than those of Ca2+ in EPS with abundant -NH2, which were responsible for selective adsorption. These findings might provide a valuable approach for treating Cd-contaminated water bodies.
摘要：
Microplastics (MPs) and heavy metals often coexist in soil, however their interactions and effects on the soil–plant system remain largely unclear. In this study, ramie (Boehmeria nivea L.) was exposed to soil contaminated with lead (Pb) and polystyrene (PS) of different sizes, dosages, and surface–charged functional groups. This design aimed to simulate the effects of MPs on phytoremediation. The experimental results revealed that PS exacerbated the damaging effects of Pb on ramie. Compared to the effect of Pb alone, PS–COOH had a greater influence on root vigor, leading to a 15.6 % reduction in the active absorption ratio. Laser scanning confocal microscope showed PS entered the roots. Adsorption/desorption experiments demonstrated that PS had a weaker adsorption capacity for Pb than soil but a greater desorption rate than soil when simulating rhizosphere secretion. Moreover, PS reduced soil pH and increased the reducible state of Pb by 6–12 %. After 100 days of phytoremediation, Pb content in the soil with PS–5 μm was 150 μg g−1 less than that in the soil without PS. These results demonstrated that PS improved Pb bioavailability and enhanced the efficiency of Pb uptake by ramie. The redundancy analysis demonstrated that PS mitigated the toxicity of Pb to rhizosphere microorganisms, potentially via its effects on metal chemical fractions, dehydrogenase activity (S–DHA), cation exchange capacity (CEC), and soil organic matter (SOM). This study indicates that the presence of PS could potentially enhance the phytoremediation efficiency of ramie in Pb–contaminated land by influencing soil microenvironmental properties. This study provides insights into the complex interactions of MPs with soil–plant–microbial systems during metal remediation, thereby enhancing our understanding of their environmental impacts.
Microplastics (MPs) and heavy metals often coexist in soil, however their interactions and effects on the soil–plant system remain largely unclear. In this study, ramie (Boehmeria nivea L.) was exposed to soil contaminated with lead (Pb) and polystyrene (PS) of different sizes, dosages, and surface–charged functional groups. This design aimed to simulate the effects of MPs on phytoremediation. The experimental results revealed that PS exacerbated the damaging effects of Pb on ramie. Compared to the effect of Pb alone, PS–COOH had a greater influence on root vigor, leading to a 15.6 % reduction in the active absorption ratio. Laser scanning confocal microscope showed PS entered the roots. Adsorption/desorption experiments demonstrated that PS had a weaker adsorption capacity for Pb than soil but a greater desorption rate than soil when simulating rhizosphere secretion. Moreover, PS reduced soil pH and increased the reducible state of Pb by 6–12 %. After 100 days of phytoremediation, Pb content in the soil with PS–5 μm was 150 μg g−1 less than that in the soil without PS. These results demonstrated that PS improved Pb bioavailability and enhanced the efficiency of Pb uptake by ramie. The redundancy analysis demonstrated that PS mitigated the toxicity of Pb to rhizosphere microorganisms, potentially via its effects on metal chemical fractions, dehydrogenase activity (S–DHA), cation exchange capacity (CEC), and soil organic matter (SOM). This study indicates that the presence of PS could potentially enhance the phytoremediation efficiency of ramie in Pb–contaminated land by influencing soil microenvironmental properties. This study provides insights into the complex interactions of MPs with soil–plant–microbial systems during metal remediation, thereby enhancing our understanding of their environmental impacts.
摘要：
Hydrochar serves not only as a fuel source but also as a versatile carbon material that has found extensive application across various domains. The application performance of hydrochar, e.g., energy recovery and carbon stability, is substantially influenced by its mass yield, higher heating value (HHV), and compositions (C, H, O, N, S, and ash), so the prediction and engineering of these properties is promising. In this study, two machine learning algorithms, namely gradient boosting regression (GBR) and random forest (RF), were used to predict the hydrochar properties mentioned above. The GBR models (with test regression coefficient (R2) values of 0.87-0.98 for single-target prediction and average test R2 of 0.93 for multi-target prediction) exhibited superior predictive capabilities to the RF models (with test R2 of 0.78-0.97 for single-target and average test R2 of 0.90 for multi-target prediction). The interpretation of ML models revealed the importance ranking of features for all targets. Then, engineering hydrochar was carried out through three different optimizations to the as-built multi target prediction model: i) optimizations of HTC conditions for given biomass samples; ii) optimization of biomass mixture recipes; iii) simultaneous optimization of both biomass mixing recipes and HTC conditions.
摘要：
Background and aimsIntercropping is known to have low fertilizer input but high production efficiency. However, only few studies have explored the nutrient stoichiometry of soil and microbiome under intercropping patterns to understand the mechanisms underlying the improvement in crop production by intercropping.MethodsA field-based experiment (started in 2013) was conducted to explore the effects of intercropping of maize with peanut, soybean, gingelly, and sweet potato on soil microbial resource limitation, and the factors controlling the resource limitation were investigated by exploring functional gene abundance and soil C-N-P stoichiometry.ResultsVector angle (indicator of microbial P limitation) was > 45 & DEG; in all soil samples. Compared with monocropping, intercropping significantly decreased the vector length and angle. The RC:N-TERC:N was < 0 and the RC:P-TERC:P was > 0 in all soil samples. The RC:P-TERC:P of the monocropping was significantly higher than that of the intercropping soil. Compared with monocropping, the abundances of most of functional genes related to C degradation and fixation, N fixation, nitrification, denitrification, and P activation increased in intercropping soil. Microbial P limitation was associated more with the C-N-P stoichiometric ratios of soil and microbiome than with functional gene abundance. Soil microbial P limitation was notably related to plant N and P uptake and maize yield, regulating by soil microbial N:P, available P:C and P:N ratio.ConclusionsThis study demonstrated the mitigation of microbial P limitation by intercropping and highlighted the importance of understanding the promotion of microbial metabolisms by soil resource stoichiometry, which can help in improving maize productivity.
