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Article

Regulatory Effects of Different Biochar on Soil Properties and Microbial Community Structure in Chrysanthemum Continuous Cropping Soil

by
Yang Feng
1,†,
Xin Hu
2,†,
Yanhuan Guan
3,†,
Zhixuan Chu
3,†,
Xianfeng Du
2,
Yuyan Xie
2,
Shiqi Yang
2,
Siru Ye
2,
Lei Zhang
2,
Jinyi Ma
3,* and
Haoming Chen
2,*
1
School of Art and Design, Xijing University, Xi’an 710123, China
2
School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
3
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
*
Authors to whom correspondence should be addressed.
†
These authors have contributed equally to this work.
Agronomy 2024, 14(9), 2034; https://doi.org/10.3390/agronomy14092034
Submission received: 7 August 2024 / Revised: 1 September 2024 / Accepted: 4 September 2024 / Published: 6 September 2024
(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability—Volume II)
Browse Figures
Versions Notes

Abstract

:
Chrysanthemum, an agricultural economic crop with ornamental, medicinal, and edible values, faces the problem of continuous cropping obstacles in its cultivation. As a potential soil conditioner used to address continuous cropping obstacles (CCOs), the applicability of biochar in chrysanthemum cultivation has become a research hotspot. This study explored the effects of three different types of biochar (rice straw biochar = RB, pig manure biochar = PB, and sludge biochar = SB) on soil for chrysanthemum that had been continuously cultivated for eight years through pot experiments. The results indicate that the addition of biochar significantly reduced soil water loss. Compared with CK, the water retention rates of the SB and PB treatments increased by 25.4% and 18.4%, respectively. In the PB treatment, the contents of available phosphorus (AP) and available potassium (AK) increased by 85% and 164%, respectively. The available nitrogen (AN) content showed the highest increase under the SB treatment. All three types of biochar could improve the pH value of chrysanthemum soil with CCOs (increased by 0.4–5.4%). The results of microbial community diversity showed that, compared with CK, PB and RB slightly reduced the diversity of bacterial communities in chrysanthemum soil with CCOs (by 1.50% and 0.41%, respectively). However, the SB treatment increased the diversity of bacterial communities in chrysanthemum soil with CCOs (by 0.41%). At the same time, SB and PB significantly inhibited the diversity of fungal communities (reduced by 15.15% and 6.67%, respectively), while RB promoted the diversity of fungal communities (increased by 5.45%). Furthermore, the analysis results of bacterial phyla and genera indicated that PB and SB had enhancing effects on the beneficial bacterial phylum Actinobacteriota (8.66% and 4.64%) and the beneficial bacterial genus Nocardioides (23.29% and 9.69%). Additionally, the PB treatment enhanced the beneficial bacterial phylum Firmicutes (7.03%). The analysis results of fungal genera and phyla indicated that PB contributed to an increase in the beneficial fungal phylum Ascomycota (1.51%). RB significantly enhanced the beneficial fungal genus Chaetomium (56.34%). Additionally, all three types of biochar effectively reduced the abundance of the harmful fungal phylum Basidiomycota (30.37–73.03%). In the PB and SB treatments, the harmful fungal phylum Mucoromycota was significantly decreased (by 36.22% and 62.60%, respectively). Finally, all three types of biochar reduced the abundance of harmful fungal genera Acremonium (1.15–35.19%) and Phoma (97.1–98.7%). In this study, we investigated the effect of three kinds of biochar (RB, PB, and SB) on the soil of chrysanthemum continuous cropping through potting experiments and found that they could significantly reduce water loss, enhance water retention, increase the soil nutrient content, improve the pH value, regulate microbial communities, increase beneficial microorganisms, and reduce harmful microorganisms. These results provide a scientific basis for addressing barriers to continuous cropping (CC) while supporting the sustainability of agriculture and the development of agroecology.

1. Introduction

Chrysanthemum is one of the traditional flowers in China. Because of its landscape appreciation and edible and medicinal values, chrysanthemum has gradually attracted people’s attention, and the global demand for chrysanthemum production is also increasing [1,2]. For example, in China, the planting area of cut chrysanthemum exceeds 7000 hectares, and the annual sales reach 2.65 billion sprays with a sales volume of CNY 1.52 billion [3]. However, with the increase in chrysanthemum planting years, the problem of continuous cropping obstacles (CCOs) will gradually occur. Soil CCOs are often manifested in decreases in the soil bulk density and pH value, soil nutrient loss, decrease in enzyme activity, and soil microbial community structure imbalance [4]. These soil problems caused by continuous cropping (CC) will have a negative impact on plant growth. Compared with 2 years of CC, the yield of stevia decreased by 28.38% compared with that of CC carried out for 8 years [5]. Therefore, the high demand for soil quality in chrysanthemums greatly increases the cost of growing chrysanthemums.
The decline in soil physical/chemical properties and the imbalance of microbial community are two important reasons for soil CCOs. Suitable physical and chemical conditions in the soil guarantee plant growth. For example, nitrogen (N) can increase the content of chlorophyll in plant leaves so as to promote plant growth [6]. Phosphorus (P) is one of the most important macronutrients for plant growth and yield, which is the key component of nucleic acids, phospholipids, and several enzymes [7]. Compared with other flower plants, chrysanthemum has a high demand for soil nutrients. Studies have found that the contents of N, P, and potassium (K) in the soil of chrysanthemum planted for 15 years are only 83.37%, 57.31%, and 46.19% of that of chrysanthemum planted for 1 year, respectively [8]. Furthermore, the imbalance of nutrients in the soil also limits plant growth and causes sensitivity to environmental changes [9]. In addition, plant rhizosphere microorganisms and secretions can create a specific soil microenvironment [10].
With CC, the imbalance of soil microbial communities may lead to a marked decline in crop yields and an increase in the disease incidence rate [11,12], for example, the significant increase in fungal communities destroying the microbial community of the original chrysanthemum rhizosphere soil, which is one of the main soil biological characteristics that lead to chrysanthemum CCOs [13]. Compared with 1 year, the total number of Fusarium oxysporum and fungi increased by 34–79% and 53–107% in monocropping soils in 2–4 consecutive years, while the yield of Chuju flowers decreased by 11–37% [14]. Therefore, increasing soil nutrients and weakening the content of fungi may be the key to improving the soil of chrysanthemum CCOs. However, existing studies on chrysanthemum mostly focus on gene improvement and medicinal value extraction [15,16]. The research on soil restoration for chrysanthemum CCOs is still in its early stages.
For soil CCOs, existing remediation technologies include soil modifier application, chemical control, biological treatment, etc. [17,18]. Among them, soil amendment/remediation agent is one of the most commonly used tools with the least technical difficulty and the lowest economic cost. Biochar, a soil remediation agent, is produced by the pyrolysis of biomass under hypoxic or hypoxic conditions [19]. Biochar has a wide range of raw materials, especially organic solid waste, such as straw, pig manure, sludge, dead branches, etc. [20,21]. Its rich porous structure and nutrient elements enable biochar to regulate the soil pore structure and improve soil water retention and fertility [22]. In addition, biochar has a good effect on the stability of the soil microbial community structure and the inhibition of pathogenic bacteria [23]. For example, corn straw biochar can significantly increase the bacterial biomass in the CC soil of vanilla orchid by 1.49 times and reduce the fungal biomass by 99.91% [24]. In addition, biochar can promote soil microbial activity, diversity, and evenness [25], which may help to improve the imbalance in the soil microbial community caused by CC. However, the application of biochar in repairing the soil of chrysanthemum CCOs is still in the research stage, and it will be one of the important research directions in the future.
The objectives of this study were to investigate the improvement effects of three distinct types of biochar on chrysanthemum soil with CCOs and to compare and analyze the influence mechanisms of these biochars on the soil’s physical, chemical, and biological properties at short timescales. This study underscores the use of biochar as an efficacious means of utilizing agricultural solid waste, offering a novel idea and method for optimizing chrysanthemum planting modes and mitigating cultivation costs. The results of this study contribute to the sustainable management of chrysanthemum cultivation and promote sustainable agricultural development and ecological civilization.

2. Materials and Methods

2.1. Materials

The soil samples were meticulously collected from a chrysanthemum cultivation field (continuous cropping for 8 years) in the greenhouse at Nanjing Hushu (31°48′ N, 118°56′ E), ensuring a consistent sampling depth ranging from 0 to 20 cm. In the laboratory, meticulous care was taken to remove plant roots, insects, stones, and other soil detritus from the samples. Subsequently, the samples underwent a natural drying process in a cool, well-ventilated area, followed by mechanical reduction using a wooden stick to achieve a uniform texture. Post-crushing, the soil was meticulously sieved through a 50-mesh sieve to ensure particle uniformity, with the resulting particles being less than 0.15 mm for storage purposes. The experiment incorporated three distinct biochars: an alkaline rice husk biochar (RB, pyrolyzed at 450 °C), a weakly alkaline pig manure biochar (PB, pyrolyzed at 450 °C), and a weakly acidic sludge biochar (SB, pyrolyzed at 650 °C). The rice husk and pig manure biochars were procured from the Soil Research Institute of the Chinese Academy of Sciences in Nanjing, China. In contrast, the sludge biochar was obtained from Mississippi International Water Ltd., located in Hangzhou, Zhejiang, China. A comprehensive overview of the fundamental physical and chemical attributes of these biochars is delineated in Table 1.

2.2. Experimental Design

The pot experiment was carried out in an artificial climate chamber designed to assess the effects of different biochars on chrysanthemum growth and soil properties in soil with CCOs. The experiment comprised four treatments: CC soil without biochar (control, CK), CC soil amended with RB, CC soil amended with PB, and CC soil amended with SB. Each treatment group was replicated four times, resulting in a total of 32 samples. For each pot, 20 g of chrysanthemum soil with CCOs and 1 g of the respective biochar were homogeneously mixed and transferred into a 150 mL pot. The pots were then positioned in an artificial climate chamber set at a temperature of 25 °C and a humidity level of 60% for 10 days and subjected to a photoperiod of 12 h of light followed by 12 h of darkness (RDN-300C-4, Southeast Instrument in Ningbo, China). The soil moisture was maintained at 60% of the saturated soil moisture content by adjusting it every 3 days. Destructive sampling was performed after 10 days of incubation. The collected soil samples were divided into two portions. One portion was immediately stored at −20 °C for short-term preservation to measure the soil microbial community, while the other was used to analyze the soil’s physical and chemical properties. This experimental design allowed for the evaluation of biochar’s impact on soil health and soil microbial community, providing insights into the potential for biochar to mitigate issues associated with CC in chrysanthemum production systems.

2.3. Characterization of Biochar and Soil Properties

Soil moisture content was determined by the drying method (105 °C, 8 h), and soil bulk density was determined by the cutting ring method. The soil pH was determined using a portable pH meter (PHBJ-260, Wuxi Lei Ci Instrument Co., Ltd., China) (soil/water ratio of 1:5). Available nitrogen (AN), available phosphorus (AP), available potassium (AK), and soil organic matter (SOM) were measured in all soil samples. The AN was measured using the semi-Kjeldahl method [26]. The AP was extracted using Olsen-P extraction [22], AK was extracted by NH4OAC, AP was determined by the molybdenum antimony anti-colorimetric method [27], and K was determined by the flame photometry method [28]. Soil samples (biochar was removed with forceps) were air-dried, ground, and passed through a 100-mesh sieve, and the SOM content was measured using the potassium dichromate oxidation–external heating method [29].

2.4. Determination of Soil Microbial Community Diversity

The soil samples used for high-throughput analysis were put into ice boxes and brought back to the laboratory for storage in ultra-low-temperature refrigerators. The sequencing process includes extraction of gene DNA, production of amplicon, mixing and purification of PCR products, library preparation, and sequencing. DNA was extracted from the samples using the E.Z.N.A. ® Soil DNA Kit (Omega Bio-tek, Norcross, GA, USA). Extracted DNA was detected by 1% agarose gel electrophoresis. Using primers 515F 5′-barcode-GTGCCAGCMGCCGCGG)-3′ and 907R 5′-CCGTCAATTCMTTTRAGTTT-3′, where the barcode is an eight-base sequence unique to each sample, the V4-V5 region of the bacterial 16S ribosomal RNA gene was amplified by PCR (amplification at 95 °C for 2 min, followed by amplification at 95 °C for 25 cycles for 30 s, amplification at 55 °C for 30 s, amplification at 72 °C for 30 s, and finally, amplification at 72 °C for 5 min). PCR was performed using the TransStart Fastpfu DNA Polymerase 20 μL reaction (ABI GeneAmp®9700 model, Thermo Fisher Scientific, USA). Amplicons were extracted from 2% agarose gels and purified using the AxyPrep DNA Gel Extraction Kit (Axygen Biosciences, Union City, CA, USA). Purified PCR products were quantified using Qubit®3.0 (Life Invitrogen, Thermo Fisher Scientific, USA). In this experiment, 16SrDNA/ITS genes of different regions (16S V3-V5, ITS1) were sequenced using the Paired End method based on the Illumina MiSeq sequencing platform [30].
QIIME (version1.9.0 http://qiime.org/scripts/assign_taxonomy.html, accessed on 6 August 2024) was used for sequence analysis. To study the microbial diversity of samples, UCLUST was used to obtain OTU at 97% similarity level in QIIME; OTU was then classified and annotated based on the Silva (bacteria) and Unite (fungi) classification databases. By comparing OTU’s representative sequences with microbial reference databases, taxonomic information for each OTU could be obtained. The microbiome of each sample was composed of taxonomic level (phylum, class, order, family, genus, and species), and correlation charts were drawn using QIIME and R.

2.5. Statistical Analysis

Excel 2013 and R version 3.4.1 were used to conduct variance analysis on the changes in soil nutrient content and microbial community abundance (genus level). Multiple comparisons were made between soil nutrient content and microbial changes on the first day and the tenth day of culture. Origin 8.0 was used to generate relevant figures, etc.

3. Results

3.1. Effects of Different Biochar on Soil Physical and Chemical Properties

The addition of biochar significantly reduced water loss in the soil. Compared with CK, water retention under the SB and PB treatments increased by 25.4% and 18.4% (Table 2). There was no significant difference in water retention between RB and CK. The AK, AP, AN, and pH value of the soil increased significantly after the addition of biochar. Compared with CK, the contents of AP and AK under the PB treatment increased by 85% and 164%, respectively. The content of AN under the SB treatment was the highest. In the short term, the three types of biochar can improve the pH of chrysanthemum soil with CCOs, but the difference is not significant. In addition, biochar addition also reduced the content of SOM.

3.2. Effect of Biochar Application on Soil Microbial Community Structure

(1)
PCoA
A principal co-ordinate analysis (PCoA) was conducted on the bacterial communities in chrysanthemum soil with CCOs in different treatment groups (Figure 1A). Three axes (PC1, PC2, and PC3) explained 26.25%, 20.37%, and 16.27% of the sample differences, respectively. The PCoA results show that the distance between the center of CK and the center of SB was the smallest, at 238.8. The three axes (PC1, PC2, and PC3) in the principal coordinate analysis of the fungal community explained 62.88%, 17.45%, and 6.00% of the sample differences, respectively (Figure 1B). The difference between CK and SB is the largest (the center distance is 3548.9), and the difference between CK and PB is the smallest (the center distance is 2142.5).
(2)
OTU Venn
An OTU Venn analysis of the bacterial community in this test is shown in Figure 2A. A total of 7668 OTUs were obtained from samples of four different treatments, and 2776 OTUs were shared by the four treatments, accounting for 36.2% of the total. The number of unique OTUs in the PB treatment, RB treatment, and SB treatment was 601, 668, and 837, accounting for 7.8%, 8.7%, and 10.9% of the total number, respectively. In addition, the OTU results show that the bacterial communities of the biochar treatments were different from that of the CK treatment, among which the SB treatment was the most significant.
An OTU Venn analysis of the fungal community in this study is shown in Figure 2B. A total of 992 OTUs were obtained, and four treatments shared 333 OTUs, accounting for 33.6% of the total. The number of unique OTUs in the PB treatment, RB treatment, and SB treatment was 100, 107, and 57, accounting for 10.1%, 10.8%, and 5.7% of the total number, respectively. Compared with CK, PB and RB promoted fungal species, while SB inhibited fungal species.
(3)
Diversity index analysis
According to Table 3, the bacterial and fungal community coverages under the different treatments reached over 96.90% and 99.60%, almost covering all bacterial and fungal communities in soil with CCOs for chrysanthemum. In the bacterial community, compared with CK, the ACE estimator and Chao estimator of PB and RB were lower than that of CK. Meanwhile, the Shannon index of PB and RB decreased by 1.50% and 0.41%, respectively, indicating that PB and RB can reduce the diversity of bacterial community in chrysanthemum soil with CCOs. However, the SB treatment can promote the diversity of bacterial community in chrysanthemum soil with CCOs (increased by 0.41%). Compared with CK, the Simpson index of PB and RB increased, while SB did not change significantly.
In the fungal community, the ACE estimator and Chao estimator of the three biochar treatments decreased, indicating that the addition of biochar will reduce the richness of fungal community in the chrysanthemum soil with CCOs. Compared with CK, the Shannon index of RB increased by 5.45%, and that of SB and PB decreased by 15.15% and 6.67%, respectively. SB and PB may significantly inhibit the diversity of the fungal community, while RB can promote it.
(4)
Heatmap analysis of microorganism communities
A heatmap analysis classifies and aggregates samples based on the similarity of their abundances. Dark red indicates a higher relative abundance and stronger promotion of microbial growth, while dark blue indicates a lower relative abundance and stronger inhibition of microbial growth. The results of the bacterial heatmap show that Proteobacteria, Actinobacteria, Chloroflexi, and Gemmatimonadota were the most abundant bacteria in chrysanthemum soil with CCOs. Caldisericum, Margulisbacteria, Synergista, TA06, and TX1A-33 were low in abundance and inhibited by growth in all treatments. Compared with CK, the Bacteria_Unclassified richness of each treatment decreased after biochar addition (PB decreased by 10.44%, RB decreased by 28.36%, and SB decreased by 37.31%). The Elusimicrobiota richness of PB decreased by 47.18%, that of RB increased by 14.71% and that of SB increased by 23.53%. In addition, the abundance of MBNT15 increased significantly after biochar addition (PB decreased by 5.94%, RB increased by 27.72%, and SB increased by 4.95%).
The results of the bacterial heatmap at the level of genera in different treatments show that the abundances of Vicinamibacterales_norank, Gemmataceae_uncultured, Vicinamibacteraceae_norank, and Sphingomonas were very high. The growth of PLTA13_norank, Steroidobacteraceae_uncultured, and Elsterales_norank was inhibited. Compared with other bacterial genera, the EcFYyy-200 genera showed the most significant difference after biochar addition, the richness of CK treatment was extremely low, and the richness of PB, RB, and SB increased by 21.1%, 50.93%, and 1.86%, respectively.
Ascomycota was the most abundant fungal taxon in chrysanthemum CC soil (darkest blue, see Figure 3). Chytridiomycota and Zoopagomycota were low in abundance, and their growth was inhibited across all treatments. Compared with the CK group, the richness of Basidiomycota decreased to some extent after biochar addition (PB decreased by 30.4%, RB by 49.3%, and SB by 73.0%). At the genus level, Botryotrichum, Schizothecium, Fusarium, and Humicola were highly abundant, whereas Acrostalagmus, Phlebiopsis, and Pseudogymnoascus exhibited inhibited growth (Figure 4). The richness values of Chaetomium in PB and SB were 41.9% and 56.5% lower, respectively, than that in CK, while the richness of Chaetomium in RB was 6.0% higher than that in CK.

3.3. Analysis of Relative Abundance of Phylum and Genus Level Communities

According to the 16S rDNA/ITS1 species sequencing results, the relative abundances of phylum and genus communities of bacteria and fungi are shown in Figure 5 and Figure 6. In the classification of bacteria at the phylum level, bacteria in chrysanthemum soil with CCOs can be roughly divided into 46 groups. Studies have shown that Actinobacteriota can improve the contents of AN, AP, and AK [31], and Firmicutes can promote cellulose degradation and carbon cycling [32]. Compared with CK, the abundance of Actinobacteriota in RB decreased by 14.69%, that of PB increased by 8.66%, and that of SB increased by 4.64%. Among the three biochar treatments, Actinobacteriota in PB was the most abundant, which was 27.37% higher than RB and 3.84% higher than SB. In addition, compared with CK, the abundance of Firmicutes under the RB treatment decreased by 25.49%, that under the PB treatment increased by 7.03%, and that under the SB treatment decreased by 2.73%.
At the bacterial genus level, the bacteria in chrysanthemum soil with CCOs can be roughly divided into 957 major populations. Studies by relevant scholars show that Gemmatimonadaceae_uncultured, Nocardioides, and Lysobacter belong to beneficial bacteria. Gemmatimonadaceae_uncultured is associated with N2O and NO2− reduction as well as N2 production [33], Nocardioides can be used to degrade a wide range of organic pollutants (such as ibuprofen, chlorophenols, pyridine, etc.) [34], while Lysobacter can inhibit soil-borne pathogens and reduce the damage of allelopathic autotoxin substances to roots [35]. Therefore, according to the results of previous studies, this study found that the abundance of Gemmatimonadaceae_unculture under the RB, PB, and SB treatments decreased by 23.52%, 20.97%, and 7.73%, respectively, compared with CK. The Gemmatimonadaceae_uncultured of SB had the highest richness, which was 20.65% more than RB and 16.75% more than PB. Among the three biochar treatments, PB had the highest abundance of Nocardioides. Compared with CK, the abundance of Nocardioides in PB and SB increased by 23.29% and 9.69%, respectively, while that in RB decreased by 14.93%. Furthermore, compared to CK, RB, PB, and SB inhibited the growth of Lysobacter, with decreases of 45.54%, 12.88%, and 18.42%, respectively.
This study identified five primary phyla of soil fungi, with Ascomycota being the dominant group (Figure 6A). Related studies have shown that Ascomycota fungi can decompose lignified vegetation debris and SOM [36], which can regulate soil nutrients. The fungi of Basidiomycota will cause wood decay [37]. There is a very harmful parasitic fungi in Chytridiomycota [38]. The fungi of Mucoromycota are present in decaying fruit and crop residues and cause harm to human beings [39]. Some Zoopagomycota fungi can cause a large number of deaths of susceptible insects [40]. Therefore, Basidiomycota, Mucoromycota, Chytridiomycota, and Zoopagomycota were defined as harmful fungi in this study. The abundance of Ascomycota under the PB treatment was the highest, which was 1.51%, 11.40%, and 3.53% more than CK, RB, and SB, respectively. In the category of harmful fungi, the abundance of Basidiomycota in PB, RB, and SB was lower than that in CK, with decreases of 30.37%, 49.25%, and 73.03% in PB, RB, and SB, respectively. Compared with CK, the abundance of Mucoromycota in RB increased by 17.55%, while that in PB and SB decreased by 36.22% and 62.60%.
At the genus level, soil fungi can be roughly divided into 219 large populations (Figure 6B). Previous studies have shown that Chaetomium fungi species can biocontrol many plant pathogens [41]. Therefore, we classify them as beneficial fungi. Fusarium fungi species can cause wilt disease in chrysanthemum [42], Phoma fungi species can cause tea plant diseases [43], and Acremonium is a plant pathogen that can also infect humans [44]. Therefore, we classify Fusarium, Phoma, and Acremonium as harmful fungi.
Among the results for beneficial fungi, the abundance of Chaetomium in RB was the highest, with a 56.34% increase compared to CK. The abundance of Chaetomium in PB and SB (25.62% and 17.10%) was lower than that in CK. Among the harmful fungi, the abundance of Fusarium under the SB treatment was 0.26% lower than that in CK, while the abundance of Fusarium in RB (53.94%) and PB (11.78%) was higher than that in CK. The application of the three biochars reduced the abundance of Acremonium and Phoma. Compared with CK, the abundance of Acremonium in RB, PB, and SB decreased by 1.15%, 35.19%, and 31.91%, respectively. The abundance of Phoma under the RB, PB, and SB treatments decreased by 97.10%, 98.26%, and 98.70%, respectively.

4. Discussion

4.1. Effects of Different Biochars on Soil Physicochemical Properties of Chrysanthemum with Continuous Cropping Obstacles

According to this study, biochar can be used not only to remove pollutants from the environment and reduce greenhouse gas emissions and energy production, but also to improve soil quality and address CCOs [45,46]. The pore structure of biochar can effectively improve the soil water content and soil permeability [47]. In this study, the water retention capacity of soil disturbed by chrysanthemum CC was measured by water loss in 3 days. The results show that SB regulated soil water retention the best, while RB and PB had no obvious improvement effect. Meanwhile, the soil pH and SOM content are pivotal indicators of soil health, and the application of biochar has been shown to increase both [48]. The application of RB, PB, and SB increased the soil pH, but the degree of increase was different, and PB increased it the most. However, the SOM content showed a downward trend after biochar application, which may have been due to the low amount of biochar application. Among them, PB showed the least decrease, while RB showed the most decrease. However, the SOM content tended to decrease after the application of biochar, which may have been due to the adsorption of SOM by the biochar itself. On the other hand, the addition of biochar helped microorganisms to multiply, which undoubtedly also increased the consumption of SOM. Moreover, one of the important ways for biochar to repair soil with CCOs is to improve the imbalance of nutrient elements such as N, P, and K caused by CC [49]. For example, after the application of biochar under continuous culture of tobacco, significant increases in conductivity, AN, AP, and AK were observed, alleviating the problem of CCOs [50]. In this study, three kinds of biochar all effectively increased the contents of AK, AP, and AN in chrysanthemum soil with CCOs. The contents of AK and AP were most significantly increased by PB, and the content of AN was most increased by SB. According to previous research, chrysanthemum cultivation depletes the soil of K and N more than P [51], which also means that PB and SB can be better targeted to compensate for the nutrient depletion of chrysanthemum cultivation soils.

4.2. Effect Mechanisms of Different Biochars on Soil Microbial Community in Chrysanthemum with Continuous Cropping Obstacles

Microorganisms play a crucial role in facilitating the circulation and transformation of substances and the flow of energy within the soil [52]. The diversity, metabolic activity, and community composition of microorganisms in rhizosphere soil serve as indicators of soil health [53]. It is found that under CC conditions, the microbial population in the inter-root soil decreases, the variety of bacterial and fungal species decreases significantly, and the population of pathogenic bacteria increases [54]. For example, succession cropping reduces the number of beneficial soil bacteria such as Verrucomicrobia, Gemmatimonadetes, Actinobacteria, and Acidobacteria while increasing the biomass of pathogenic fungi such as Phoma, Volutella, and Fusarium [55]. In this study, a bacterial community α diversity index analysis showed that SB application improved bacterial community diversity in chrysanthemum soil with CCOs to a certain extent. According to the OTU number of unique bacterial communities in each treatment, the bacterial abundance under the SB treatment was the highest, which was also consistent with the α diversity index analysis, followed by the CK and RB treatments, and finally, the PB treatment. There were differences in the bacterial community composition between different biochar applications and the CK treatment. Compared with the RB and PB treatments, the SB treatment had the least inhibitory effect on Gemmatimonadaceae_unculture genera in the bacterial community (Figure 5B). The bacterial abundance and diversity under the PB treatment were similar to those under the RB treatment, but PB promoted the growth of beneficial bacteria (Nocardioides) and had a lower inhibitory effect on Lysobacter.
In the fungal community, according to the α diversity index analysis, compared with CK, the richness of the soil fungal community decreased after the SB treatment, while the other two kinds of biochar applications had no significant difference. In terms of the fungal community OTU number, the RB treatment had the largest number of unique OTUs, followed by the PB treatment and CK treatment, and finally, the SB treatment. The three-dimensional PCoA analysis results show that the distance between SB and the CK was the longest, indicating that there was a large difference between them, while the distance between PB and the CK was the shortest, and the corresponding difference was also the smallest. It is noteworthy that, compared to RB and PB, SB exhibits a more pronounced inhibitory effect on harmful fungi such as Fusarium, Acremonium, and Phoma (as shown in Figure 6B). This inhibitory effect can be attributed to indirect mechanisms involved in plant disease control, including induced resistance, alterations in beneficial microbial communities, nutrient regulation, and the production of biological toxins [56]. It is important to note that the accumulation of fungal viruses and harmful bacteria in rhizosphere soil may kill plant cells or produce toxins that inhibit plant growth [57]. In conclusion, there were differences in the fungal community composition between different biochar applications and the control group. Simultaneously, biochar application can effectively improve the microbial community structure in soil.

4.3. Regulation of Beneficial and Harmful Microorganisms in Chrysanthemum Soil with Continuous Cropping Obstacles by Different Biochars

In the remediation of the soil community structure with CCOs, it is more desirable to simultaneously increase beneficial flora and decrease harmful flora. Based on the results of community improvement by the three types of biochar (Table 4), we found that their effects on succession-impaired soils varied greatly. PB and SB had more significant effects on improving both the bacterial and fungal community structures in chrysanthemum soil with CCOs, while RB primarily focused on improving fungal communities. PB exhibited a stronger promotional effect on beneficial bacteria. Compared with the control (CK), the abundance of Actinobacteriota increased by 8.66%, and the mass ratios of AN, AP, and AK were significantly improved. Firmicutes abundance increased by 7.03%, promoting cellulose degradation and carbon cycling. SB demonstrated a better inhibitory effect on harmful fungi. Compared with the CK, SB reduced the abundance of Basidiomycota, a known cause of crop diseases, by 73.11%. Additionally, the abundance of Fusarium species, which cause Fusarium wilt in chrysanthemum, decreased by 0.26%. The abundance of Acremonium also reduced by 31.91%. RB had a significant effect on improving fungal communities but may have an inhibitory effect on some beneficial bacterial phyla or genera. Therefore, RB is not suitable for the improvement of chrysanthemum soil.

5. Conclusions

In the face of the problems of soil quality decline and microbial community imbalance caused by chrysanthemum CCOs, this study confirmed that biochar has significant potential to significantly improve the soil nutrient status and microbial community structure in the short term. In particular, the application of biochar promoted increases in the AK, AP, and AN contents and pH value in the soil. Among them, PB showed the most significant improvement effect on AP (increased by 85%) and AK (increased by 164%) in soils with CCOs, while sludge biochar mainly excelled in enhancing the soil water retention capacity and increasing AN (increased by 48.84%). In addition, SB and RB optimized the diversity of bacterial and fungal communities, respectively. Notably, in promoting the growth of beneficial microbial communities and inhibiting harmful microbial communities, pig manure and sludge biochars exhibit more pronounced advantages compared to RB. Specifically, PB and SB not only promote the proliferation of beneficial bacterial phyla (Actinobacteriota and Firmicutes) and genera (Nocardioides) but also increase the abundance of beneficial fungal phyla (Ascomycota). At the same time, they also effectively inhibit the growth of harmful fungal phyla (Basidiomycota and Mucoromycota) and genera (Fusarium, Acremonium, and Phoma). This study revealed that PB and SB could quickly adjust the soil physical and chemical properties, improve the microbial community structure in barrier soil, and restore soil ecological functions. Future studies will further explore the effect of the combined application of these two types of biochar on the soil properties of chrysanthemum obstacles and its effect on the growth of chrysanthemum flowers, which will provide a new scientific basis for solving the problem of CCOs.

Author Contributions

Conceptualization, J.M. and H.C.; methodology, H.C. and Y.F.; validation, X.D., Y.X. and H.C.; formal analysis, S.Y. (Shiqi Yang), S.Y. (Siru Ye), L.Z., Y.G. and Z.C.; resources, H.C. and J.M.; writing—original draft preparation, Y.F. and X.H.; writing—review and editing, H.C.; supervision, J.M.; funding acquisition, H.C. All authors have read and agreed to the published version of the manuscript.

Funding

This study was supported by the Fundamental Research Funds for the Central Universities (No. 30924010938), the Open Fund for Large Instrumentation of the Nanjing University of Science and Technology (2024), the Postgraduate Research and Practice Innovation Program of Jiangsu Province (SJCX24_0158), and the Chunhui Talent Project of the Hebei Provincial Natural Science Foundation (E2023519001).

Data Availability Statement

The data can be found within the article.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Lin, G.H.; Lin, L.; Liang, H.W.; Ma, X.; Wang, J.Y.; Wu, L.P.; Jiang, H.D.; Bruce, I.C.; Xia, Q. Antioxidant Action of a Chrysanthemum morifolium Extract Protects Rat Brain Against Ischemia and Reperfusion Injury. J. Med. Food 2010, 13, 306–311. [Google Scholar] [CrossRef] [PubMed]
  2. Yoon, J.B.; Choi, S.K.; Cho, I.S.; Kwon, T.R.; Yang, C.Y.; Seo, M.H.; Yoon, J.Y. Epidemiology of tomato spotted wilt virus in Chrysanthemum morifolium in South Korea and its management using a soil-dwelling predatory mite (Stratiolaelaps scimitus) and essential oils. Virus Res. 2020, 289, 198128. [Google Scholar] [CrossRef]
  3. Wang, T.; Yang, K.X.; Ma, Q.Y.; Jiang, X.; Zhou, Y.Q.; Kong, D.L.; Wang, Z.Y.; Parales, R.E.; Li, L.; Zhao, X.; et al. Rhizosphere Microbial Community Diversity and Function Analysis of Cut Chrysanthemum During Continuous Monocropping. Front. Microbiol. 2022, 13, 801546. [Google Scholar] [CrossRef]
  4. Tan, G.; Liu, Y.J.; Peng, S.G.; Yin, H.Q.; Meng, D.L.; Tao, J.M.; Gu, Y.B.; Li, J.; Yang, S.; Xiao, N.W.; et al. Soil potentials to resist continuous cropping obstacle: Three field cases. Environ. Res. 2021, 200, 111319. [Google Scholar] [CrossRef] [PubMed]
  5. Xu, X.J.; Luo, Q.Y.; Wei, Q.C.; Jiang, S.T.; Dong, C.X.; Faruque, M.O.; Huang, Z.W.; Xu, Z.H.; Yin, C.X.; Zhu, Z.B.; et al. The Deterioration of Agronomical Traits of the Continuous Cropping of Stevia Is Associated With the Dynamics of Soil Bacterial Community. Front. Microbiol. 2022, 13, 917000. [Google Scholar] [CrossRef] [PubMed]
  6. Lin, Y.C.; Hu, Y.G.; Ren, C.Z.; Guo, L.C.; Wang, C.L.; Jiang, Y.; Wang, X.J.; Hlatshwayo, P.; Zeng, Z.H. Effects of Nitrogen Application on Chlorophyll Fluorescence Parameters and Leaf Gas Exchange in Naked Oat. J. Integr. Agric. 2013, 12, 2164–2171. [Google Scholar] [CrossRef]
  7. Roch, G.V.; Maharajan, T.; Ceasar, S.A.; Ignacimuthu, S. The Role of PHT1 Family Transporters in the Acquisition and Redistribution of Phosphorus in Plants. Crit. Rev. Plant Sci. 2019, 38, 171–198. [Google Scholar] [CrossRef]
  8. Liu, X.; Xiao, Y.; Dai, C. Preliminary study on the causes of continuous cropping obstacles of medicinal chrysanthemum in Yancheng. Soils 2012, 44, 1035–1040. (In Chinese) [Google Scholar] [CrossRef]
  9. McQueen, D.J.; Shepherd, T.G. Physical changes and compaction sensitivity of a fine-textured, poorly drained soil (Typic Endoaquept) under varying durations of cropping, Manawatu Region, New Zealand. Soil Tillage Res. 2002, 63, 93–107. [Google Scholar] [CrossRef]
  10. Qin, H.C.; Wang, Z.X.; Sha, W.Y.; Song, S.H.; Qin, F.J.; Zhang, W.C. Role of Plant-Growth-Promoting Rhizobacteria in Plant Machinery for Soil Heavy Metal Detoxification. Microorganisms 2024, 12, 700. [Google Scholar] [CrossRef]
  11. Li, J.; Cheng, X.Y.; Chu, G.X.; Hu, B.W.; Tao, R. Continuous cropping of cut chrysanthemum reduces rhizospheric soil bacterial community diversity and co-occurrence network complexity. Appl. Soil Ecol. 2023, 185, 104801. [Google Scholar] [CrossRef]
  12. Li, J.; Meng, F.; Chen, N.N.; Jiang, M.B.; Chu, G.X.; Tao, R. Loss in the rare bacterial diversity drives the monocropping obstacle of cut chrysanthemum. J. Soil Sci. Plant Nutr. 2024, 24, 2774–2785. [Google Scholar] [CrossRef]
  13. Xiao, X.; Zhu, W.; Du, C.; Shi, Y.-D.; Wang, J.-F. Effects of crop rotation and bio-organic manure on soil microbial characteristics of Chrysanthemum cropping system. Chin. J. Appl. Ecol. 2015, 26, 1779–1784. [Google Scholar]
  14. Wang, J.F.; Li, X.L.; Xing, S.Z.; Ma, Z.Y.; Hu, S.J.; Tu, C. Bio-organic Fertilizer Promotes Plant Growth and Yield and Improves Soil Microbial Community in Continuous Monoculture System of Chrysanthemum morifolium cv. Chuju. Int. J. Agric. Biol. 2017, 19, 563–568. [Google Scholar]
  15. Nguyen, T.K.; Lim, J.H. Tools for Chrysanthemum genetic research and breeding: Is genotyping-by-sequencing (GBS) the best approach? Hortic. Environ. Biotechnol. 2019, 60, 625–635. [Google Scholar] [CrossRef]
  16. Hadizadeh, H.; Samiei, L.; Shakeri, A. Chrysanthemum, an ornamental genus with considerable medicinal value: A comprehensive review. S. Afr. J. Bot. 2022, 144, 23–43. [Google Scholar] [CrossRef]
  17. Li, Y.; Fang, F.; Wei, J.L.; Wu, X.B.; Cui, R.Z.; Li, G.S.; Zheng, F.L.; Tan, D.S. Humic Acid Fertilizer Improved Soil Properties and Soil Microbial Diversity of Continuous Cropping Peanut: A Three-Year Experiment. Sci. Rep. 2019, 9, 12014. [Google Scholar]
  18. Tang, L.; Hamid, Y.; Chen, Z.Q.; Lin, Q.; Shohag, M.J.I.; He, Z.L.; Yang, X.E. A phytoremediation coupled with agro-production mode suppresses Fusarium wilt disease and alleviates cadmium phytotoxicity of cucumber (Cucumis sativus L.) in continuous cropping greenhouse soil. Chemosphere 2021, 270, 128634. [Google Scholar] [CrossRef]
  19. Chen, H.M.; Ma, J.Y.; Wei, J.X.; Gong, X.; Yu, X.C.; Guo, H.; Zhao, Y.W. Biochar increases plant growth and alters microbial communities via regulating the moisture and temperature of green roof substrates. Sci. Total Environ. 2018, 635, 333–342. [Google Scholar] [CrossRef]
  20. Zhao, F.Z.; Tang, L.Y.; Song, W.J.; Jiang, H.F.; Liu, Y.P.; Chen, H.M. Predicting and refining acid modifications of biochar based on machine learning and bibliometric analysis: Specific surface area, average pore size, and total pore volume. Sci. Total Environ. 2024, 948, 174584. [Google Scholar] [CrossRef]
  21. Xu, X.Y.; Schierz, A.; Xu, N.; Cao, X.D. Comparison of the characteristics and mechanisms of Hg(II) sorption by biochars and activated carbon. J. Colloid Interface Sci. 2016, 463, 55–60. [Google Scholar] [CrossRef] [PubMed]
  22. Chen, H.M.; Du, X.F.; Lai, M.Q.; Nazhafati, M.; Li, C.; Qi, W.C. Biochar Improves Sustainability of Green Roofs via Regulate of Soil Microbial Communities. Agriculture 2021, 11, 620. [Google Scholar] [CrossRef]
  23. Zhang, G.X.; Guo, X.F.; Zhu, Y.E.; Liu, X.T.; Han, Z.W.; Sun, K.; Ji, L.; He, Q.S.; Han, L.F. The effects of different biochars on microbial quantity, microbial community shift, enzyme activity, and biodegradation of polycyclic aromatic hydrocarbons in soil. Geoderma 2018, 328, 100–108. [Google Scholar] [CrossRef]
  24. Zhao, Q.F.; MA, H.Y.; Wang, H.; Wang, H.; Zhao, Q.Y. Effects of Biochar on Vanilla planifolia Growth and Rhizosphere Soil Microbial Community Structure. Hubei Agric. Sci. 2015, 54, 5647–5651. (In Chinese) [Google Scholar] [CrossRef]
  25. Zhang, M.Y.; Wang, J.; Bai, S.H.; Teng, Y.; Xu, Z.H. Evaluating the effects of phytoremediation with biochar additions on soil nitrogen mineralization enzymes and fungi. Environ. Sci. Pollut. Res. 2018, 25, 23106–23116. [Google Scholar] [CrossRef]
  26. Ding, Y.; Wang, J.; Jia, J.; Han, Q.; Zhang, N. Determination of crude protein of tongbai Glycine soja seeds and discussion of methods. Guihaia 2013, 33, 122–125. [Google Scholar]
  27. Hu, L.a.; Qiu, J.; Li, Q. Stoichiometric characteristics of soil carbon, nitrogen and phosphorus in different stages of vegetation succession at karst graben basin of Yunnan Province, China. Carsologica Sin. 2023, 42, 1213–1223. [Google Scholar]
  28. Wen, Y.M.; You, J.W.; Zhu, J.; Hu, H.Q.; Gao, J.S.; Huang, J. Long-term green manure application improves soil K availability in red paddy soil of subtropical China. J. Soils Sediments 2021, 21, 63–72. [Google Scholar] [CrossRef]
  29. Wang, Z.R.; Hasi, E.; Han, X.J.; Qingda, M. Fractal characterization of soil particle size distribution under different land use patterns on the north slope of Wula Mountain in China. J. Soils Sediments 2024, 24, 1148–1164. [Google Scholar] [CrossRef]
  30. Chen, K.H.; Longley, R.; Bonito, G.; Liao, H.L. A Two-Step PCR Protocol Enabling Flexible Primer Choice and High Sequencing Yield for Illumina MiSeq Meta-Barcoding. Agronomy 2021, 11, 1274. [Google Scholar] [CrossRef]
  31. Mitra, D.; Mondal, R.; Khoshru, B.; Senapati, A.; Radha, T.K.; Mahakur, B.; Uniyal, N.; Myo, E.M.; Boutaj, H.; Sierra, B.E.G.; et al. Actinobacteria-enhanced plant growth, nutrient acquisition, and crop protection: Advances in soil, plant, and microbial multifactorial interactions. Pedosphere 2022, 32, 149–170. [Google Scholar] [CrossRef]
  32. Huang, J.J.; Gao, K.L.; Yang, L.; Lu, Y.H. Successional action of Bacteroidota and Firmicutes in decomposing straw polymers in a paddy soil. Environ. Microbiome 2023, 18, 76. [Google Scholar] [CrossRef]
  33. He, K.W.; Han, R.X.; Wang, Z.; Xiao, Z.F.; Hao, Y.L.; Dong, Z.Z.; Xu, Q.; Li, G. Soil source, not the degree of urbanization determines soil physicochemical properties and bacterial composition in Ningbo urban green spaces. Sci. Total Environ. 2024, 930, 172550. [Google Scholar] [CrossRef] [PubMed]
  34. Benedek, T.; Pápai, M.; Gharieb, K.; Bedics, A.; Táncsics, A.; Tóth, E.; Daood, H.; Maróti, G.; Wirth, R.; Menashe, O.; et al. Nocardioides carbamazepini sp. nov., an ibuprofen degrader isolated from a biofilm bacterial community enriched on carbamazepine. Syst. Appl. Microbiol. 2022, 45, 126339. [Google Scholar] [CrossRef]
  35. Chen, D.M.; Li, Z.M.; Huang, C.Y.; Yang, H.J. Self-digestive solution of Lysobacter enzymogenes LE16 as a biofungicide to control plant powdery mildew. Arch. Agron. Soil Sci. 2023, 69, 2898–2910. [Google Scholar] [CrossRef]
  36. Bai, X.L.; Zhang, E.; Wu, J.M.; Ma, D.H.; Zhang, C.H.; Zhang, B.Y.; Liu, Y.P.; Zhang, Z.; Tian, F.; Zhao, H.; et al. Soil fungal community is more sensitive than bacterial community to modified materials application in saline-alkali land of Hetao Plain. Front. Microbiol. 2024, 15, 1255536. [Google Scholar] [CrossRef]
  37. Saitta, A.; Bernicchia, A.; Gorjón, S.P.; Altobelli, E.; Granito, V.M.; Losi, C.; Lunghini, D.; Maggi, O.; Medardi, G.; Padovan, F.; et al. Biodiversity of wood-decay fungi in Italy. Plant Biosyst. 2011, 145, 958–968. [Google Scholar] [CrossRef]
  38. Van den Wyngaert, S.; Ganzert, L.; Seto, K.; Rojas-Jimenez, K.; Agha, R.; Berger, S.A.; Woodhouse, J.; Padisak, J.; Wurzbacher, C.; Kagami, M.; et al. Seasonality of parasitic and saprotrophic zoosporic fungi: Linking sequence data to ecological traits. ISME J. 2022, 16, 2242–2254. [Google Scholar] [CrossRef] [PubMed]
  39. Richardson, M. The ecology of the Zygomycetes and its impact on environmental exposure. Clin. Microbiol. Infect. 2009, 15, 2–9. [Google Scholar] [CrossRef]
  40. Nibert, M.L.; Debat, H.J.; Manny, A.R.; Grigoriev, I.V.; Licht, H.H.D. Mitovirus and Mitochondrial Coding Sequences from Basal Fungus Entomophthora muscae. Viruses 2019, 11, 351. [Google Scholar] [CrossRef]
  41. Zhao, S.S.; Zhang, Y.Y.; Yan, W.; Cao, L.L.; Xiao, Y.; Ye, Y.H. Chaetomium globosum CDW7, a potential biological control strain and its antifungal metabolites. Fems Microbiol. Lett. 2017, 364, fnw287. [Google Scholar] [CrossRef] [PubMed]
  42. Balamurugan, A.; Ashajyothi, M.; Shanu, K.; Charishma, K.; Varun, H.; Gunjeet, K.; Kumar, A. Chrysanthemum wilt caused by Fusarium incarnatum: Etiology unveiled through polyphasic taxonomic methods. Physiol. Mol. Plant Pathol. 2024, 129, 102214. [Google Scholar] [CrossRef]
  43. Yang, R.; Jiang, S.L.; Li, D.X.; Yin, Q.X.; Wu, X.; Wang, Y.; Wang, D.L.; Chen, Z. Integrated mRNA and Small RNA Sequencing for Analyzing Leaf Spot Pathogen Didymella segeticola and Its Host, Tea (Camellia sinensis), During Infection. Mol. Plant-Microbe Interact. 2021, 34, 127–130. [Google Scholar] [CrossRef] [PubMed]
  44. Summerbell, R.C.; Gueidan, C.; Guarro, J.; Eskalen, A.; Crous, P.W.; Gupta, A.K.; Gené, J.; Cano-Lira, J.F.; van Iperen, A.; Starink, M.; et al. The Protean Acremonium. A-sclerotigenum/egyptiacum: Revision, Food Contaminant, and Human Disease. Microorganisms 2018, 6, 88. [Google Scholar] [CrossRef] [PubMed]
  45. Dissanayake, P.D.; You, S.M.; Igalavithana, A.D.; Xia, Y.F.; Bhatnagar, A.; Gupta, S.; Kua, H.W.; Kim, S.; Kwon, J.H.; Tsang, D.C.W.; et al. Biochar-based adsorbents for carbon dioxide capture: A critical review. Renew. Sustain. Energy Rev. 2020, 119, 109582. [Google Scholar] [CrossRef]
  46. You, S.M.; Ok, Y.S.; Tsang, D.C.W.; Kwon, E.E.; Wang, C.H. Towards practical application of gasification: A critical review from syngas and biochar perspectives. Crit. Rev. Environ. Sci. Technol. 2018, 48, 1165–1213. [Google Scholar] [CrossRef]
  47. Bayat, H.; Mazaheri, B.; Mohanty, B.P. Estimating soil water characteristic curve using landscape features and soil thermal properties. Soil Tillage Res. 2019, 189, 1–14. [Google Scholar] [CrossRef]
  48. Useviciute, L.; Baltrenaite-Gediene, E.; Feiziene, D. The Combined Effect of Biochar and Mineral Fertilizer on Triticale Yield, Soil Properties under Different Tillage Systems. Plants 2022, 11, 111. [Google Scholar] [CrossRef]
  49. Ma, H.J.; Lin, L.; Xu, S.G.; Chen, Z.B.; Fan, Z.W.; Jiang, M.X.; Li, Y. Preparation and characterization of biochar and its effects on soil properties, rhizosphere bacterial and tobacco yield with reduced compound fertilizer application. Mater. Express 2023, 13, 1095–1104. [Google Scholar] [CrossRef]
  50. Zhao, L.Y.; Guan, H.L.; Wang, R.; Wang, H.J.; Li, Z.C.; Li, W.; Xiang, P.; Xu, W.M. Effects of Tobacco Stem-Derived Biochar on Soil Properties and Bacterial Community Structure under Continuous Cropping of Bletilla striata. J. Soil Sci. Plant Nutr. 2021, 21, 1318–1328. [Google Scholar] [CrossRef]
  51. Kaplan, L.; Tlustos, P.; Szakova, J.; Najmanova, J.; Brendova, K. The effect of NPK fertilizer with different nitrogen solubility on growth, nutrient uptake and use by chrysanthemum. J. Plant Nutr. 2016, 39, 993–1000. [Google Scholar] [CrossRef]
  52. Reynolds, H.L.; Packer, A.; Bever, J.D.; Clay, K. Grassroots ecology: Plant-microbe-soil interactions as drivers of plant community structure and dynamics. Ecology 2003, 84, 2281–2291. [Google Scholar] [CrossRef]
  53. Dong, L.L.; Xu, J.; Feng, G.Q.; Li, X.W.; Chen, S.L. Soil bacterial and fungal community dynamics in relation to Panax notoginseng death rate in a continuous cropping system. Sci. Rep. 2016, 6, 31802. [Google Scholar]
  54. Zhang, J.F.; Luo, S.Y.; Yao, Z.M.; Zhang, J.F.; Chen, Y.L.; Sun, Y.; Wang, E.Z.; Ji, L.; Li, Y.X.; Tian, L.; et al. Effect of Different Types of Continuous Cropping on Microbial Communities and Physicochemical Properties of Black Soils. Diversity 2022, 14, 954. [Google Scholar] [CrossRef]
  55. Liu, H.; Pan, F.J.; Han, X.Z.; Song, F.B.; Zhang, Z.M.; Yan, J.; Xu, Y.L. A comprehensive analysis of the response of the fungal community structure to long-term continuous cropping in three typical upland crops. J. Integr. Agric. 2020, 19, 866–880. [Google Scholar] [CrossRef]
  56. de Araujo, A.S.; Blum, L.E.B.; Andrade, D.V.N.; da Silva, P.B.; de Figueiredo, C.C. Sewage Sludge Biochar Effects on Phytopathogenic Fungi and Beneficial Microorganisms. Braz. Arch. Biol. Technol. 2021, 64, e21210266. [Google Scholar] [CrossRef]
  57. Manici, L.M.; Caputo, F.; Saccà, M.L. Secondary metabolites released into the rhizosphere by Fusarium oxysporum and Fusarium spp. as underestimated component of nonspecific replant disease. Plant Soil 2017, 415, 85–98. [Google Scholar] [CrossRef]
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Figure 1. Three-dimensional PCoA map of soil bacterial community (A) and soil fungi community (B); 95% confidence interval.
Figure 1. Three-dimensional PCoA map of soil bacterial community (A) and soil fungi community (B); 95% confidence interval.
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Figure 2. Venn plots of soil bacteria (A) and fungi (B) community composition. Note: red, blue, green, and yellow represent CK, PB, RB, and SB treatments, respectively.
Figure 2. Venn plots of soil bacteria (A) and fungi (B) community composition. Note: red, blue, green, and yellow represent CK, PB, RB, and SB treatments, respectively.
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Figure 3. Heatmaps of bacterial phylum level (A) and bacterial genus level (B) of soil under different treatments.
Figure 3. Heatmaps of bacterial phylum level (A) and bacterial genus level (B) of soil under different treatments.
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Figure 4. Heatmaps of fungal phylum level (A) and fungal genus level (B) of soil under different treatments.
Figure 4. Heatmaps of fungal phylum level (A) and fungal genus level (B) of soil under different treatments.
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Figure 5. Abundance plots of bacterial phyla level (A) and bacterial genera level (B) under different treatments.
Figure 5. Abundance plots of bacterial phyla level (A) and bacterial genera level (B) under different treatments.
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Figure 6. Abundance plots of fungal phyla level (A) and fungal genera level (B) under different treatments.
Figure 6. Abundance plots of fungal phyla level (A) and fungal genera level (B) under different treatments.
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Table 1. The physical and chemical properties of the biochars.
Table 1. The physical and chemical properties of the biochars.
MaterialsBET Surface Area
(m2/g)		Total Pore Volume
(cm3/g)		pHTP (%)TN (%)TK (%)
RB27.690.0217.811.320.170.11
PB130.640.0718.601.212.382.43
SB35.780.0786.361.711.730.27
RB—rice biochar; PB—pig manure biochar; SB—sludge biochar.
Table 2. Physical and chemical properties of soil after improvement.
Table 2. Physical and chemical properties of soil after improvement.
Treatment Group3-Day Water Loss
(g)		Available Potassium (mg/kg)Available Phosphorus
(mg/kg)		Available Nitrogen
(mg/kg)		Soil
pH		Organic Matter (g) (without Biochar)
CK1.14 ± 0.02579.7064.17116.877.450.0732
RB1.13 ± 0.07861.0766.09128.627.510.0531
PB0.93 ± 0.061027.0875.70154.067.850.0619
SB0.85 ± 0.05793.2369.85173.957.480.0544
CK—soil with continuous cropping obstacles; RB—rice biochar; PB—pig manure biochar; SB—sludge biochar.
Table 3. Diversity and abundance indexes of bacteria and fungi in soil improved with biochar.
Table 3. Diversity and abundance indexes of bacteria and fungi in soil improved with biochar.
Sample IDReads0.97
OTUACEChaoCoverageShannonSimpson
BacteriaCK44,4514456515450640.977887.380.0015
RB31,4733797455144710.969067.270.0017
PB43,1834365508349850.976037.350.0016
SB42,9854559531451670.975777.410.0015
FungiCK44,0605616696580.997003.300.1525
RB42,6645436456300.996993.080.2018
PB49,9905216015950.997783.480.1055
SB42,3374966185960.996882.800.2430
Table 4. Regulatory effects of beneficial and harmful microorganisms of biochar in chrysanthemum succession barrier soils.
Table 4. Regulatory effects of beneficial and harmful microorganisms of biochar in chrysanthemum succession barrier soils.
Improvement of Beneficial Microorganisms (%)Reduction in Harmful Microorganisms (%)
Bacterial
Phylum		Bacterial
Genus		Fungal
Phylum		Fungal
Genus		Fungal
Phylum		Fungal
Genus
RB///Chaetomium (56.34%)Basidiomycota (49.25%)Acremonium (1.15%)
Phoma (97.10%)
PBActinobacteriota (8.66%)
Firmicutes (7.03%)		Nocardioides (23.29%)Ascomycota (1.51%)/Basidiomycota (30.37%)
Mucoromycota (36.22%)		Acremonium (35.19%)
Phoma (98.26%)
SBActinobacteriota (4.64%)Nocardioides (9.69%)//Basidiomycota (73.03%)
Mucoromycota (62.60%)		Fusarium (0.26%)
Acremonium (31.91%)
Phoma (98.70%)
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Feng, Y.; Hu, X.; Guan, Y.; Chu, Z.; Du, X.; Xie, Y.; Yang, S.; Ye, S.; Zhang, L.; Ma, J.; et al. Regulatory Effects of Different Biochar on Soil Properties and Microbial Community Structure in Chrysanthemum Continuous Cropping Soil. Agronomy 2024, 14, 2034. https://doi.org/10.3390/agronomy14092034

AMA Style

Feng Y, Hu X, Guan Y, Chu Z, Du X, Xie Y, Yang S, Ye S, Zhang L, Ma J, et al. Regulatory Effects of Different Biochar on Soil Properties and Microbial Community Structure in Chrysanthemum Continuous Cropping Soil. Agronomy. 2024; 14(9):2034. https://doi.org/10.3390/agronomy14092034

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Feng, Yang, Xin Hu, Yanhuan Guan, Zhixuan Chu, Xianfeng Du, Yuyan Xie, Shiqi Yang, Siru Ye, Lei Zhang, Jinyi Ma, and et al. 2024. "Regulatory Effects of Different Biochar on Soil Properties and Microbial Community Structure in Chrysanthemum Continuous Cropping Soil" Agronomy 14, no. 9: 2034. https://doi.org/10.3390/agronomy14092034

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