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Article

Impact of Organic Fertilization Strategies on Soil Bacterial Community and Honey Pomelo (Citrus maxima) Properties

by
Jinbiao Li
1,2,3,
Zhike Wei
1,
Lin Tao
1,
Jingqi Zhong
1,
Xiumei Liu
2,3,
Jianhua Ji
2,3,
Xianjin Lan
2,3,
Hongqian Hou
2,3,
Zhaobin Feng
2,3,
Jingshang Xiao
2,3,
Anyong Hu
1,
Yiren Liu
2,3 and
Zhenzhen Lv
2,3,*
1
School of Geographical Science, Nantong University, Nantong 226019, China
2
Soil and Fertilizer & Resources and Environmental Institute, Jiangxi Academy of Agricultural Sciences, Nanchang 330200, China
3
China National Engineering and Technology Research Center for Red Soil Improvement, Nanchang 330200, China
*
Author to whom correspondence should be addressed.
Agronomy 2024, 14(10), 2244; https://doi.org/10.3390/agronomy14102244
Submission received: 31 August 2024 / Revised: 20 September 2024 / Accepted: 27 September 2024 / Published: 29 September 2024
(This article belongs to the Section Soil and Plant Nutrition)
Browse Figures
Versions Notes

Abstract

:
Soil health is a critical factor in sustainable agriculture, particularly in fruit production, where fertilization strategies play a vital role in maintaining the soil quality and enhancing fruit production and quality. This study investigates the effects of different fertilization strategies on soil bacterial communities and honey pomelo (Citrus maxima) properties in Ji’an City, Jiangxi Province, China. Three fertilization treatments were compared: conventional fertilization (CF: botanical organic plus chemical compound fertilizers), organic material fermented fertilization (OF: organic material including duck manure fermented fertilizer plus chemical compound fertilizer), and a special honey pomelo fertilizer (SF: organic material fermented fertilizer only during the whole honey pomelo growing season). Soil samples were collected at two depths (0–20 cm and 20–40 cm) from nine plots (three treatments × three replicates) and analyzed for their soil properties, bacterial community diversity and composition, and fruit characteristics. The results indicate that the OF and SF significantly improved the soil pH, soil organic matter (SOM), and nutrient availability compared to the CF. Additionally, the OF and SF treatments led to a 13.6% and 16.6% increase in fruit weight, respectively, and higher bacterial diversity, although no significant differences were observed in fruit quality parameters such as vitamin C, soluble sugar, and titratable acid. Acidobacteriota, Proteobacteria, Actinobacteria, and Chloroflexi were the dominant bacterial phyla. The soil bacterial composition structures were significantly different among the different fertilization strategies, and were well explained by soil properties such as the pH, SOM, total phosphorus, and available nutrients. Our study suggests that applying fermented organic fertilizers which use duck manure as part of the raw materials, either alone or in combination with chemical compound fertilizers, increases honey pomelo fruit production and improves soil health, contributing to the sustainable development of orchards.

1. Introduction

Soil fertility is a critical factor in orchard productivity, influencing the fruit yield and quality [1]. In recent years, there has been an increasing focus on sustainable managing practices, particularly in fruit production, where fertilization strategies play a vital role in maintaining soil health and enhancing fruit properties [2,3]. Traditional agricultural practices, particularly the yield-driving intensive use of chemical fertilizers, have raised concerns about the long-term impacts of these practices on soil health due to the degradation of soil quality, loss of biodiversity, and reduced resilience to environmental stressors [2,4]. In contrast, organic and integrated fertilization strategies have emerged as alternatives, promoting a more balanced soil ecosystem and sustainable agricultural practices [5,6,7]. These methods are believed to enhance soil structure and soil microbial communities, which are crucial for nutrient cycling and plant health.
Honey pomelo (Citrus maxima) is one of the most popular citrus fruits in the world, known for its large size, sweet flavor, and nutritional value. Native to Southeast Asia, it is now cultivated in many tropical and subtropical regions, with China being one of the largest producers [8]. The fruit’s economic importance extends beyond local markets, as it is a significant export product for many countries. The successful cultivation of honey pomelo requires careful soil management. Proper irrigation and balanced, adequate levels of macronutrients (N, P, K) and micronutrients (such as Mg, Ca, Fe, and Zn) are essential for its optimal growth. The tree prefers slightly acidic to neutral soils (pH 5.0–7.0), which grant it better nutrient uptake [9]. Larger and heavier fruits, a pear-like shape with a smooth, thinner rind, and a uniform rind color have always been preferred for honey pomelo. Inadequate fertilization can lead to poor fruit development, while over-fertilization, particularly with chemical fertilizers, can cause soil degradation, reduced microbial activity, and environmental pollution [10,11].
Soil bacterial communities are a vital component of soil health, as these microorganisms play important roles in nutrient cycling, organic matter decomposition, and the suppression of soil-borne pathogens [12]. They contribute to the formation of soil structure by producing extracellular polymeric substances that help in the aggregation of soil properties, enhancing water retention and aeration [13,14,15]. Furthermore, it is believed that a diverse and balanced soil microbiome is essential for plant health, as it promotes nutrient uptake and stimulates plant immune responses [16,17]. Bacteria are the most prevalent microorganisms in soil, occupying 70–90% of its total biomass [18]. The relationship between soil bacterial communities and fertilization practices has been the subject of extensive research [12,19,20]. Understanding how different fertilization strategies affect soil bacterial communities is crucial for developing sustainable agricultural practices.
Jiangxi Ji’an has a mid-subtropical monsoon climate, characterized by warmth and abundant rainfall, making it ideal for honey pomelo cultivation. The total area of honey pomelo plantations in the city reaches 286 km2, with an annual output of about 80,000 tons [21]. Developing the honey pomelo industry is one of the effective ways to accelerate the improvement of Ji’an’s rural economy and increase fruit farmers’ income. The cultivation of honey pomelo is currently in a rapid development phase, but farmers’ soil and fertilizer management in their orchards is relatively extensive. There are issues of nutrient deficiency or excess in the soil, leading to low yields and a poor quality of honey pomelos, which poses a certain obstacle to the development of the honey pomelo industry. Given the importance of soil health for sustainable honey pomelo production, this study aims to explore the impact of different organic fertilization strategies on both soil bacterial communities and fruit properties. Specifically, we aim to assess (1) how different fertilization strategies influence soil bacterial diversity and composition; (2) the relationship between soil bacterial communities and soil and plant properties.

2. Materials and Methods

2.1. Study Site Description

The study site was located at Jinggangshan High-Tech Agricultural Science and Technology Park (114°17′44.16″ E, 26°45′13.32″ N) in Ji’an City, Jiangxi Province, China. This park was selected as the study site due to its combination of advanced agricultural technologies and ideal management practices. Additionally, the honey pomelo trees, planted in 2017, provided a suitable setting for observing the effects of fertilizer application. This area has a typical humid subtropical climate with a mean annual temperature of 18.3 °C and a mean annual precipitation of 1460 mm. The soil type is red soil formed from quaternary shallow metamorphic rocks. The spacing of the honey pomelo trees was 4 by 6 m. Three fertilization strategies were applied in 2022 with three replicates each to 9 plots according to a completely randomized block design. Each plot contained 6 honey pomelo trees with an area of 120 m2.

2.2. Fertilization Strategies

In this study, three fertilization strategies were adopted, including conventional fertilization strategy (CF: commercial organic + compound chemical fertilizers), organic material fermented fertilization strategy (OF: organic fermented + compound chemical fertilizers), and the special honey pomelo fertilization strategy (SF: organic fermented fertilizer only). The CF was commercial fermented botanical organic fertilizer which was provided by Nanchang Jiurun Agriculture Development Co. Ltd. (Jiangxi, China). According to the manufacturer’s label, the botanical organic material mainly included rapeseed, soybean, corn, and cassava residue, and the N, P, and K content (on percentage basis) of the CF was 2.6%, 0.65%, and 2.08%, respectively. The OF was self-fermented using 70% asparagus straw, 10% duck manure, and 20% rice husk, with Paenibacillus sp., Bacillus megaterium, and Bacillus subtilis (all belong to the genus Bacillus) added (0.1 g/kg) in a 40-day procedure; these bacteria are expected to promote nitrification, reduce ammonia emissions, increase lactic acid bacteria, and enhance carbon humification during the fermentation process [22,23]. The N, P, and K content of the OF was 1.35%, 3.69%, and 1.98%, respectively. The OF also contained approximately 2.56 ×  108 colony-forming units (counted by a nutrient agar plate colony-counting method [24]) of viable bacteria per g−1 dry weight of OF. The SF strategy entailed organic fermented fertilizer only during the whole honey pomelo growing season. The NPK compound fertilizer, with an N:P2O5:K2O ratio of 12:18:15 in the form of urea, ammonium phosphate, and potassium sulfate, was supplied as supplementary fertilizer to meet the nutrient needs of the honey pomelo in the CF and OF treatments. The application time and amount of these three fertilization strategies were set as follow (Table 1). All fertilizers were placed in two shallow ditches on both sides of the tree rows. Other field management practices were carried out as was usual locally.

2.3. Soil Sample Collection

Soil sampling was conducted in late October 2022, at the harvest stage of the honey pomelo. Three soil cores were collected from each plot and mixed with equal mass for depths of 0–20 cm and 20–40 cm, respectively. The soil cores were drilled 10 cm outside the dripline of the trees, and fertilizer ditches were avoided. In total, 18 soil samples were collected. Soil samples were stored in boxes with several ice bags inside them, after rocks and plant litter removal was conducted in the field, and transported to the laboratory on the same day. All soil samples were sieved through 2 mm mesh and divided into two portions. One portion was kept at 4 °C for analyses of soil properties. The other one was stored at −80 °C until DNA extraction.

2.4. Honey Pomelo and Soil Properties Determination

The weight of pomelo fruits per plant (FW) was the mean of the total fruit weights of the six plants. The Vitamin C (VC), soluble sugar (SS), and titratable acid (TA) content of the fruit pulp was determined by randomly selecting 10 fruits. Soil pH was measured in a 1:5 (w:v) soil:water suspension with a pH meter (F2-Standard, Mettler Toledo, Shanghai, China). Soil organic matter (SOM) was determined by the dichromate oxidation method [25]. Soil total nitrogen (TN) was determined by the Kjeldahl method [26]. Soil total phosphorus (TP) was determined by molybdenum blue spectrophotometric method [27]. Soil total potassium (TK) was determined by the flame photometry method after melting with sodium hydroxide [27]. Soil available N (AN), P (AP), and K (AK) were determined by the alkaline hydrolysis diffusion method, the Bray’s No. 1 method, and the ammonium acetate extraction method, respectively [27]. Soil exchangeable Ca2+ and Mg2+ were determined by ammonium acetate exchange–EDTA complexometric titration method [27].

2.5. Soil DNA Extraction and Sequencing

Soil DNA was isolated from 0.5 g of fresh soil samples using a commercial soil DNA isolation kit (OMEGA Bio-tek, Norcross, GA, USA). The concentration and quality of the extracted DNA were tested on a NanoDrop 2000 UV-Vis spectrophotometer (Thermo Scientific, Wilmington, DE, USA). The V4–V5 region of bacterial 16S rRNA genes were amplified using primers 515F (5′-GTGCCAGCMGCCGCGG-3’) and 907R (5′-CCGTCAATTCMTTRAGTTT-3′) [28]. The polymerase chain reactions (PCRs) amplifications were conducted in 20 μL reaction mixtures each containing 5 μL of 5× reaction and GC buffer, 2 μL of dNTP (2.5 mM), 1 μL of forward and reverse primers (10 μM), 2 μL of template DNA (diluted to 20 ng μL−1), 8.75 μL of ddH2O, and 0.25 μL of Q5 DNA polymerase. PCR cycling conditions were set as 98 °C for 2 min for initial denaturation, followed by 30 cycles of denaturation at 98 °C for 15 s, annealing at 55 °C for 30 s, and extension at 72 °C for 30 s, with a final extension at 72 °C for 5 min. The triplicate PCR products per sample were pooled together and purified with agarose gel DNA purification kits (AP-GX-250G, Axygen, CA, USA). Purified PCR products with equimolar amounts were sequenced on the Illumina Miseq 250 platform (Illumina Inc., San Diego, CA, USA) by the Personal Biotechnology Company (Shanghai, China).

2.6. Sequenced Data Processing

The bioinformatics analyses were processed by employing DADA2 (v1.30.0) package [29] in R software (v4.3.3) [30]. Sequences were quality filtered and denoised after primers were cut and demultiplexed, and purified paired-end sequences were then joined to generate the amplicon sequence variants (ASVs) at the 100% identify level. Taxonomic information was assigned using the SILVA database (release 138) for bacterial representative sequences [31].

2.7. Statistical Analyses

One-way ANOVA with post-hoc Tukey test was used to determine significant differences in soil properties and honey pomelo fruit weight properties. Statistics and visualization of microbiome data were performed following a tutorial of the microeco (v 1.9.0) package [32] in R, and sequences with low relative abundance (<0.0001) and occurrence frequency (<20%) were filtered out before ASV distribution, bacterial compositional analysis, alpha diversity analysis, principal coordinate analysis (PCoA), and redundancy analysis (RDA).

3. Results

3.1. Honey Pomelo and Soil Properties

The soil pH, SOM, TK, and the content of available nutrients (AP, AK, AN) were significantly affected by the application of different fertilizer treatments (Table 1). The soil pH was significantly higher in the OF and SF samples than in the CF samples in both the 0–20 cm and 20–40 cm layers. In the soil treated with the OF and SF, the SOM content was 15.2% and 18.8% higher in the 0–20 cm layer, and 7.4% and 1.2% higher in the 20–40 cm layer, respectively, compared to the soil treated with the CF (Table 1). The soil TK and available nutrients (AP, AK, and AN) content were significantly higher in the OF and SF samples than in the CF sample in both the 0–20 cm and 20–40 cm layers (Table 2). However, the soil TP, TN, Mg2+, and Ca2+ showed no significant differences among the three fertilizer treatments (Table 2).
For the honey pomelo, the mean fruit weight per plant was significantly higher in the OF and SF treatments than in the CF treatment, with increases of 13.6% and 16.6%, respectively (Table 2). However, the vitamin C, soluble sugar, and titratable acid content of the honey pomelo fruit showed no significant differences among the three fertilizers (Table 2).

3.2. Soil Bacterial Diversities

3.2.1. ASV Distribution

The mutual ASV numbers of the three fertilizer treatments were 545 and 532, representing 71.9% and 73.2% of the sequences in the 0–20 cm and 20–40 cm soil layers, respectively (Figure 1). The ASV distribution patterns were similar between the 0–20 and 20–40 cm layers.

3.2.2. Soil Bacterial Community Structure

At the phylum rank, species with a relative abundance >3% were considered dominant bacteria in this study. The dominant bacteria included Acidobacteriota (28.06% and 25.73% mean relative abundance in the 0–20 cm and 20–40 cm layer, respectively), Proteobacteria (24.00% and 22.25%), Actinobacteria (19.36% and 19.64%), and Chloroflexi (11.31% and 17.42%) (Figure 2A). Together, these four dominant phyla accounted for >80% of the sequences. In the 0–20 cm layer, compared to the CF treatment, the application of the OF decreased the relative abundance of Acidobacteriota and Chloroflexi, while it increased the relative abundance of Actinobacteriota. The application of the SF decreased the relative abundance of Proteobacteria. However, in the 20–40 cm layer, only the application of the SF decreased the relative abundance of Acidobacteriota, and the relative abundance of the other three dominant bacterial phyla were not significantly different among the three treatments.
At the genus rank, Sphingomonas, Bradyrhizobium, Occallatibacter, and Bryobacter exhibited higher relative abundances across all three treatments and both sampling layers (Figure 2B). Furthermore, RB41, Acidicaldus, and Nitrospira exhibited higher relative abundances in the SF compared to the CF and OF treatments in the 0–20 cm layer.

3.2.3. Soil Bacterial Alpha and Beta Diversities

Soil bacterial alpha diversity indices showed different patterns in the 0–20 cm and 20–40 cm layers (Figure 3). In the 0–20 cm layer, the Chao1 and Shannon values were the highest, and the PD value was the lowest under the SF treatment. The Chao1 and Shannon values were significantly higher and the PD value was significantly lower under the SF compared to the OF treatment (p > 0.05). In contrast, in the 20–40 cm layer, the Chao1 and Shannon values were the highest under the OF treatment, significantly higher than under the CF and SF treatments, while the PD value did not differ significantly among the treatments.
We employed PCoA to display the beta diversity of the soil bacterial communities (Figure 4). The PCoA1 and PCoA2 axes explained 37.1% of the total variation in community structure. The points were well separated according to different fertilizer treatments and sampling layers (Adonis test: R2 = 0.32, p < 0.001). Paired-group comparisons also revealed significant differences in the bacterial community structures among the different fertilization treatments (PerMANOVA test, p < 0.05).

3.3. Relationship between Soil Bacterial Communities, Diversities, Soil and Honey Pomelo Properties

Redundancy analysis (RDA) was applied to examine the relationships between soil properties and bacterial communities (Figure 5). The first and second axes explained 25.2% and 21.6% of the variation in soil bacterial community structure, respectively. The Mantel test results showed that the soil pH, SOM, TP, AN, AP, and AK had significant correlations with the bacterial community structure (Table 3).
The relationships between soil alpha diversity indices and the relative abundances of dominant phyla with different soil and plant properties were also tested using Pearson’s method (Figure 6). The results showed that the PD value was significantly negatively correlated with the soil pH, SOM, TK content, and FW. The relative abundance of Acidobacteriota was significantly negatively correlated with the soil pH, TK, AP, AK, and Ca2+. The relative abundance of Actinobacteriota was significantly positively correlated with the soil pH, SOM, TK, AP, AK, Ca2+, Mg2+, and FW. The relative abundance of Chloroflexi was significantly negatively correlated with the AP. The relative abundance of Gemmatimonadota was significantly positively correlated with the Ca2+.

4. Discussion

The results of this study underscore the significant influence of fertilization strategies on soil properties, bacterial communities, and honey pomelo properties. The OF and SF treatments significantly enhanced the soil properties compared to the CF (Table 1). The pH levels, the SOM, and the availability of essential nutrients such as TK, AP, and AN were notably higher under the OF and SF treatments. These improvements in soil quality suggest that the self-fermented organic fertilizer performed better in improving the soil acidic conditions and enhancing the nutrient cycling. This was probably due to the addition of duck manure when fermenting the OF. According to Xue et al. [33], adding duck manure-based fertilizer significantly increased the soil pH by 7–9%, and we got similar results: the pH was 9–10% higher under the OF and SF treatments than under the CF treatment in our study. Furthermore, compared to botanical-based fertilizer, adding manure may increase the available N, P, and K nutrients and improve their releasing process [34,35]. The absence of significant differences in TN, TP, Ca2+, and Mg2+ contents among the treatments indicates that, while organic fertilization strategies improve certain soil properties, they do not compromise the overall nutrient balance. In relatively long-term observations, it was found that both botanical- and manure-based organic fertilizers can improve soil quality [36]. It is worth noting that both the OF and SF treatments improved the production of honey pomelo (resulting in greater FW) compared to the CF, without affecting the fruit quality. This indicates that manure-based organic fertilizer may be a better fertilization strategy for honey pomelo orchards.
Soil bacterial communities play a crucial role in organic matter decomposition and nutrient cycling [37,38]. Our study revealed that different fertilization strategies had distinct impacts on the soil bacterial diversity and composition. In the 0–20 cm soil layer, the application of the OF and SF led to significant changes in the abundance of dominant bacterial phyla such as Acidobacteriota, Proteobacteria, Actinobacteriota, and Chloroflexi. In the 0–20 cm layer, the OF and SF treatments reduced the relative abundance of Acidobacteriota and Chloroflexi while they increased the relative abundance of Actinobacteria, probably due to the Acidobacteriota and Chloroflexi being oligotrophic bacteria, for which their relative abundance is usually negatively correlated with the nutrient contents [39,40,41]. Furthermore, a shift in the soil pH may alter the preferred conditions of these microbes, and the increase in readily available nutrients could lead to shifts in microbial community dynamics, favoring other groups that utilize these nutrients more effectively [42], while most Actinobacteria and Proteobacteria are generally considered to be more copiotrophic [43]. The Actinobacteria are crucial for decomposing complex organic materials, including cellulose and lignin. They thrive in nutrient-rich environments, so an increase in the amount organic fertilizers used may provide a favorable environment for Actinobacteria [44]. In the 20–40 cm layer, the effects of the fertilization strategies were less pronounced, with only a reduction in Acidobacteriota being observed under the SF treatment. This suggests that the impact of fertilization on bacterial communities may diminish with the soil depth, potentially due to lower microbial activity and nutrient availability in deeper soil layers [45,46].
This study also observed differences in alpha diversity indices (Chao1, Shannon, and PD values) among the treatments. The SF treatment resulted in higher Chao1 and Shannon indices, indicating an increased bacterial richness and evenness, particularly in the 0–20 cm layer. This is probably due to the fact that manure can introduce diverse microorganisms into soils [47]. Cui et al. [48] reported a 1.45% and 1.87% increase in diversity when manure was applied alone or in combination with chemical fertilizer, compared to no fertilization. Wang et al. [49] and Zhong et al. [50] also found a significant increase in bacterial diversity, while chemical fertilizer decreased the bacterial diversity. From these long-term studies, we can predict that, with different organic fertilization strategies, increased diversity may be maintained in soil and provide long-term benefits to honey pomelo plants.
The RDA and Pearson correlation analysis revealed strong associations between soil bacterial communities and soil properties. The soil pH, SOM, and available nutrients were significantly correlated with the bacterial structure, emphasizing the role of the soil chemistry in shaping microbial populations. The positive correlation between Actinobacteriota and key soil properties such as SOM, TK, and AP suggest that this phylum plays a pivotal role in nutrient cycling and organic matter decomposition, contributing to soil fertility [32,41].
Interestingly, we found that the PD value was negatively correlated with the soil pH, SOM, and FW. This indicates that, while a higher bacterial diversity is generally associated with soil health, it may not always correspond to better plant performance. A more specialized or efficient microbial community, as seen under the SF treatment, might be more beneficial for honey pomelo growth than a highly diverse bacterial population. On the other hand, plants may recruit specific beneficial bacteria for absorbing available nutrients for their development that lead to a lower PD diversity [51]. Both the OF and SF treatments led to significant increases in the FW compared to the CF, suggesting that adding manure not only improves soil quality but also enhances the fruit yield. However, no significant differences were observed in the vitamin C, soluble sugar, and titratable acid contents of the fruit, indicating that fertilization strategies may not directly influence the fruit quality in terms of nutritional composition.

5. Conclusions

This study highlights the significant impact of different fertilization strategies on soil bacterial communities and honey pomelo properties. The use of duck manure added to organic-based fertilizers (OF and SF) demonstrated clear benefits by improving the soil pH, SOM, and nutrient availability. The soil bacterial diversity increased, and the soil bacterial composition differed among the three fertilization strategies, as indicated by the increased relative abundance of Actinobacteria and the decreased relative abundance of Acidobacteriota and Chloroflexi in the OF and SF treatments. These improvements contributed to a more diverse and stable soil bacterial community, which is crucial for nutrient cycling and soil structure maintenance. Furthermore, the OF and SF treatments resulted in higher fruit yields without compromising the fruit quality, indicating that using with manure added material fermented fertilizers is a viable alternative to commercial fertilizers. Future research should explore the long-term effects of these fertilization strategies on soil health and productivity in orchards, as well as their potential to mitigate environmental impacts associated with conventional agriculture.

Author Contributions

Conceptualization, Y.L. and Z.L.; Data curation, Z.W., L.T. and J.Z.; Formal analysis, J.L.; Funding acquisition, Z.L.; Investigation, A.H.; Methodology, X.L. (Xiumei Liu) and J.J.; Project administration, Z.L.; Resources, Z.L.; Supervision, Y.L.; Validation, H.H., Z.F. and J.X.; Visualization, J.L.; Writing—original draft, J.L.; Writing—review & editing, X.L. (Xianjin Lan) and Z.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Young Elite Scientists Sponsorship Program by JXAST (2023QT03), the Modern Agricultural Scientific Research in the Jiangxi Province (JXXTCXQN202211), the National Natural Science Foundation of China (32060725, 32160754, 32160767), the National Key Research and Development Program of China (2023YFD1901100) and the College Students’ Innovation and Entrepreneurship Training Projects of Nantong University (202310304141Y).

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Conflicts of Interest

The authors declare no conflicts of interest.

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Agronomy 14 02244 g001
Figure 1. Venn diagram of ASV distribution of bacteria under different treatments in the 0–20 cm (A) and 20–40 cm (B) soil layer, respectively. CF, conventional fertilizer; OF, self-fermented organic fertilizer; SF, honey pomelo special fertilizer. The integer is ASV number, the percentage data are the ratio of sequence number to total sequence number.
Figure 1. Venn diagram of ASV distribution of bacteria under different treatments in the 0–20 cm (A) and 20–40 cm (B) soil layer, respectively. CF, conventional fertilizer; OF, self-fermented organic fertilizer; SF, honey pomelo special fertilizer. The integer is ASV number, the percentage data are the ratio of sequence number to total sequence number.
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Figure 2. Relative abundance of soil bacterial communities at the phylum (A) and genus (B) ranks under different treatments. CF, conventional fertilizer; OF, self-fermented organic fertilizer; SF, honey pomelo special fertilizer.
Figure 2. Relative abundance of soil bacterial communities at the phylum (A) and genus (B) ranks under different treatments. CF, conventional fertilizer; OF, self-fermented organic fertilizer; SF, honey pomelo special fertilizer.
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Figure 3. Chao1 (A), Shannon (B), and PD (C) values of the bacterial communities under different treatments. CF, conventional fertilizer; OF, self-fermented organic fertilizer; SF, honey pomelo special fertilizer. Treatments not sharing any lowercase letters are significantly different within each sampling layer in each figure (p < 0.05, Tukey’s HSD test).
Figure 3. Chao1 (A), Shannon (B), and PD (C) values of the bacterial communities under different treatments. CF, conventional fertilizer; OF, self-fermented organic fertilizer; SF, honey pomelo special fertilizer. Treatments not sharing any lowercase letters are significantly different within each sampling layer in each figure (p < 0.05, Tukey’s HSD test).
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Figure 4. PCoA analysis of soil bacterial communities under different treatments and soil layers. CF, conventional fertilizer; OF, self-fermented organic fertilizer; SF, honey pomelo special fertilizer.
Figure 4. PCoA analysis of soil bacterial communities under different treatments and soil layers. CF, conventional fertilizer; OF, self-fermented organic fertilizer; SF, honey pomelo special fertilizer.
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Figure 5. RDA analysis of soil bacterial communities under different treatments and soil layers. CF, conventional fertilizer; OF, self-fermented organic fertilizer; SF, honey pomelo special fertilizer.
Figure 5. RDA analysis of soil bacterial communities under different treatments and soil layers. CF, conventional fertilizer; OF, self-fermented organic fertilizer; SF, honey pomelo special fertilizer.
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Figure 6. Pearson correlation analysis between soil bacterial diversity indices, the relative abundance of dominant phyla, and soil and plant properties in the 0–20 cm soil layer. SOM, soil organic matter; TN, total nitrogen; TP, total phosphorus; TK, total potassium; AN, available nitrogen; AP, available phosphorus; AK, available potassium; VC, vitamin C; SS, soluble sugar; TA, titratable acid; FW, fruit weight per plant.
Figure 6. Pearson correlation analysis between soil bacterial diversity indices, the relative abundance of dominant phyla, and soil and plant properties in the 0–20 cm soil layer. SOM, soil organic matter; TN, total nitrogen; TP, total phosphorus; TK, total potassium; AN, available nitrogen; AP, available phosphorus; AK, available potassium; VC, vitamin C; SS, soluble sugar; TA, titratable acid; FW, fruit weight per plant.
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Table 1. The application time and amount of different fertilization strategies, and total N, P, and K applied per tree.
Table 1. The application time and amount of different fertilization strategies, and total N, P, and K applied per tree.
TreatmentsFertilizersJanuaryMarchMayJulyTotal N:P:K (kg tree−1)
CFCommercial organic +
compound chemical fertilizer (kg tree−1)		10 + 10 + 0.50 + 0.50 + 0.50.44:0.18:0.39
OFOrganic fermented +
compound chemical fertilizer (kg tree−1)		10 + 10 + 0.50 + 0.50 + 0.50.32:0.49:0.38
SFOrganic fermented fertilizer (kg tree−1)105550.34:0.92:0.50
Table 2. Effects of fertilizer addition on soil chemical properties and honey pomelo fruit properties and yield.
Table 2. Effects of fertilizer addition on soil chemical properties and honey pomelo fruit properties and yield.
Soil Layer0–20 cm20–40 cm
Soil PropertiesCFOFSFCFOFSF
pH4.66 + 0.06 b5.09 + 0.03 a5.16 + 0.05 a4.32 + 0.09 b4.75 + 0.08 a4.74 + 0.07 a
SOM (g kg−1)10.65 + 0.28 b12.27 + 0.08 a12.65 + 0.47 a10.05 + 0.13 b10.79 + 0.48 a10.17 + 0.12 ab
TN (g kg−1)0.71 + 0.02 a0.76 + 0.06 a0.74 + 0.05 a0.63 + 0.02 a0.66 + 0.04 a0.69 + 0.01 a
TP (g kg−1)0.75 + 0.09 a0.80 + 0.03 a0.83 + 0.05 a0.58 + 0.04 a0.62 + 0.04 a0.55 + 0.08 a
TK (g kg−1)21.53 + 1.04 b26.09 + 1.41 a24.31 + 0.45 a21.20 + 1.02 b26.22 + 0.80 a23.11 + 1.56 b
AN (mg kg−1)93.94 + 8.41 b121.53 + 3.69 a144.04 + 14.29 a62.23 + 2.66 b67.08 + 3.84 b90.71 + 6.32 a
AP (mg kg−1)118.60 + 3.81 c204.21 + 4.97 a145.04 + 3.08 c48.41 + 1.71 b109.18 + 1.42 a38.33 + 1.17 c
AK (mg kg−1)378.41 + 10.70 c656.57 + 13.86 a540.30 + 10.88 b364.96 + 6.03 c626.55 + 11.57 a411.8 + 10.98 b
Ca2+ (mg kg−1)1.38 + 0.10 b2.05 + 0.07 a1.85 + 0.12 a1.42 + 0.14 b1.86 + 0.10 a1.90 + 0.20 a
Mg2+ (mg kg−1)2.90 + 0.13 a3.36 + 0.23 a3.36 + 0.28 a3.39 + 0.26 a3.22 + 0.17 a3.35 + 0.17 a
Fruit propertiesCFOFSF
VC (mg 100 g−1)39.71 + 6.43 a34.05 + 3.87 a35.03 + 6.05 a
SS (mg g−1)67.70 + 3.14 a60.26 + 6.61 a65.47 + 8.49 a
TA (%)0.25 + 0.07 a0.30 + 0.09 a0.25 + 0.09 a
FW (kg)44.19 + 1.17 b50.21 + 1.24 a51.54 + 0.67 a
Notes: CF, conventional fertilizer; OF, self-fermented organic fertilizer; SF, honey pomelo special fertilizer; SOM, soil organic matter; TN, total nitrogen; TP, total phosphorus; TK, total potassium; AN, available nitrogen; AP, available phosphorus; AK, available potassium; VC, vitamin C; SS, soluble sugar; TA, titratable acid; FW, fruit weight per plant. Means within each sampling layer in each row not sharing any lowercase letters are significantly different (p < 0.05, Tukey’s HSD test).
Table 3. Mantel test between environmental variables and soil bacterial structure.
Table 3. Mantel test between environmental variables and soil bacterial structure.
VariablesCoefficientp Valuep. Adjusted
pH0.1690.0270.045 *
SOM0.4270.0010.002 **
TN0.1030.1780.223
TP0.3470.0010.002 **
TK0.1910.0370.053
AN0.4480.0010.002 **
AP0.4280.0010.002 **
AK0.4370.0010.002 **
Ca2+0.0460.2960.329
Mg2+−0.0860.8010.801
Notes: * p < 0.05; ** p < 0.01. SOM, soil organic matter; TN, total nitrogen; TP, total phosphorus; TK, total potassium; AN, available nitrogen; AP, available phosphorus; AK, available potassium.
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Li, J.; Wei, Z.; Tao, L.; Zhong, J.; Liu, X.; Ji, J.; Lan, X.; Hou, H.; Feng, Z.; Xiao, J.; et al. Impact of Organic Fertilization Strategies on Soil Bacterial Community and Honey Pomelo (Citrus maxima) Properties. Agronomy 2024, 14, 2244. https://doi.org/10.3390/agronomy14102244

AMA Style

Li J, Wei Z, Tao L, Zhong J, Liu X, Ji J, Lan X, Hou H, Feng Z, Xiao J, et al. Impact of Organic Fertilization Strategies on Soil Bacterial Community and Honey Pomelo (Citrus maxima) Properties. Agronomy. 2024; 14(10):2244. https://doi.org/10.3390/agronomy14102244

Chicago/Turabian Style

Li, Jinbiao, Zhike Wei, Lin Tao, Jingqi Zhong, Xiumei Liu, Jianhua Ji, Xianjin Lan, Hongqian Hou, Zhaobin Feng, Jingshang Xiao, and et al. 2024. "Impact of Organic Fertilization Strategies on Soil Bacterial Community and Honey Pomelo (Citrus maxima) Properties" Agronomy 14, no. 10: 2244. https://doi.org/10.3390/agronomy14102244

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