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Article

The Effects of Nitrogen Reduction and Sheep Manure Incorporation on the Soil Characteristics and Microbial Community of Korla Fragrant Pear Orchards

by
Wenge Xie
1,
Xing Shen
1,2,
Wei Li
1,
Linsen Yan
1,
Jie Li
1,
Bangxin Ding
1,2,* and
Zhongping Chai
1,2,*
1
College of Resources and Environment, Xinjiang Agricultural University, No. 311 East Agricultural University Road, Urumqi 830052, China
2
Xinjiang Key Laboratory of Soil and Plant Ecological Processes, Urumqi 830052, China
*
Authors to whom correspondence should be addressed.
Agronomy 2025, 15(3), 545; https://doi.org/10.3390/agronomy15030545
Submission received: 24 December 2024 / Revised: 19 February 2025 / Accepted: 20 February 2025 / Published: 23 February 2025
(This article belongs to the Section Soil and Plant Nutrition)
Browse Figures
Review Reports Versions Notes

Abstract

:
Excessive use of nitrogen fertilizer affects the sustainable development of the Korla fragrant pear orchard. Semi-decomposed sheep manure is favored because of its advantages of being pollution-free, containing more microorganisms, and being friendly to soil. However, the effects of nitrogen fertilizer combined with sheep manure on soil nutrient cycling and microbial community in pear orchards are still unclear. This study involved a two-year field experiment to investigate fertilization’s effects on the 0–20 cm soil layer of 10–12-year-old Korla fragrant pear trees at maturity. The purpose of this study was to explore the effect of reducing nitrogen fertilizer combined with sheep manure on soil fertility and microbial community in Korla fragrant pear orchard. The treatments of no nitrogen fertilizer (N0), conventional fertilization (N), 20% reduction in nitrogen based on conventional fertilization (N2), a combination of 20% nitrogen reduction with sheep manure F1 (22,500 kg·hm−2), and 20% nitrogen reduction with sheep manure F2 (33,750 kg·hm−2) formed the experimental treatment of nitrogen reduction with sheep manure, denoted as N2F1 and N2F2. The results showed that nitrogen application increased soil physicochemical indicators but decreased soil pH and bacterial community richness and diversity. After nitrogen reduction, soil total nitrogen (TN), alkaline hydrolysis nitrogen (AN), available phosphorus (AP), microbial biomass nitrogen (SMBN), bacterial community richness, fungal community evenness, and diversity were inhibited, but bacterial community diversity was increased. Nitrogen reduction combined with sheep manure treatment increased the content of nitrate nitrogen (NO3−–N), ammonium nitrogen (NH4+–N), soil organic matter (SOM), pH, microbial biomass carbon (SMBC), and SMBN and increased the evenness and diversity of the bacterial community but inhibited the richness of the bacterial community. Among them, N2F2 treatment had the best effect on SMBC and SMBN. Soil pH, NO3−–N, and SOM were the primary environmental variables influencing bacterial and fungal community levels. The application of nitrogen significantly influenced pear orchard yields, but the yield of pears treated showed no significant variation with nitrogen reduction and nitrogen reduction combined with sheep manure based on complete nitrogen application. In summary, 20% nitrogen reduction (300 kg·hm−2) combined with 22,500–33,750 kg·hm−2 sheep manure better promotes the stability and health of soil microbial communities, and the use of organic fertilizer represents the most efficient approach to quickly enhancing soil fertility and the variation of microbial communities. These findings are highly relevant when improving land productivity, ensuring food security, and promoting environmental sustainability in fruit tree farming.

1. Introduction

Fertilization plays a crucial role in improving plant nutrient uptake and ensuring high crop productivity, while also influencing soil properties. In recent years, the negative impacts of excessive nitrogen fertilizer use, such as soil acidification, environmental degradation, and loss of biodiversity, have become increasingly evident [1,2]. Additionally, studies have demonstrated that inorganic nitrogen fertilizers can reduce rates of microbial respiration, extracellular enzyme activity, and bacterial diversity while inhibiting overall soil microbial activity [3,4]. Sustainable improvements in soil’s physicochemical properties and biological characteristics can be accomplished by reducing chemical fertilization and incorporating more organic nutrient sources [5]. Human activities, especially the intensification of agriculture and prolonged fertilization practices, exert a notable influence on microbial communities in the soil. These microbes play a vital role in energy transfer and nutrient cycling, supporting agricultural productivity through processes such as the decomposition of organic matter, nutrient mineralization, soil functionality, and the absorption of nutrients by plants [6]; therefore, for the sustainable development of agricultural ecosystems, a deeper understanding of the intricate responses of microbial communities to different organic and inorganic fertilization systems is crucial.
Organic fertilizer is rich in microorganisms and can effectively enhance the structure of the microbial community by altering the soil’s bacteria-to-fungi ratio [7]. Moreover, applying organic fertilizer elevates levels of soil organic matter (SOC), which contains abundant carbon, nitrogen, phosphorus, and potassium, creating a conducive environment for microbial growth and fostering greater diversity within microbial communities [8], and earlier research has demonstrated that the addition of diverse nutrients through organic fertilizers effectively supports the maintenance of the soil’s dynamic life system. However, relying on a single type of organic fertilizer is insufficient to meet the demands of practical agricultural production [9,10]. Numerous studies have demonstrated that the use of chemical fertilizers alone heightens the risk of soil nutrient leaching. In contrast, integrating chemical fertilizers with organic additives, such as organic manure, straw, or biochar, has proven effective in minimizing nutrient loss through leaching [11,12]. Applying organic amendments while reducing the use of inorganic fertilizers represents both an economically viable and environmentally sustainable approach to promoting sustainable agricultural practices. Han et al. [13] demonstrated that addition of different organic amendments significantly affected the maize biomass and physicochemical properties of newly reclaimed soils with a 50% reduction in fertilizer input. Zhang et al. [14] found, through a 15-year field trial, that blending chemical fertilizers with straw or cow dung can increase crop yields while preserving soil fertility and buffering capacity. Lazcano et al. [15] conducted a short-term field experiment and showed that replacing 25% of nutrients with vermicompost or manure and obtaining the remaining 75% of nutrients from inorganic fertilizers significantly increased soil microbial activity while maintaining nutrient availability comparable to that of inorganic fertilizers. Earlier investigations have shown that integrating organic and inorganic fertilizers can promote microbial growth, alter the soil microbial community structure, and enhance enzyme activity. Whether or not chemical fertilizers are applied, organic fertilizer application positively influences bacterial and fungal diversity [7].
The Xinjiang Korla pear is known as China’s “national geographical indication”, known for its sweet taste, crisp texture, rich aroma, and high nutritional value. Despite its reputation, excessive nitrogen fertilizer use, unregulated fertilization practices, and imbalanced fertilization ratios hinder the current cultivation of Korla fragrant pears. Additionally, disruptions to the soil C/N ratio, soil acidification, and a declining soil microbiological environment further undermine the quality and productivity of the orchards, endangering their sustainable development. Sheep manure is abundant and readily available in Xinjiang, whereas cow manure has a lower nitrogen content, a denser texture, and a less pronounced effect on soil microorganisms. Compared to compost, semi-decomposed sheep manure provides a longer nutrient release period. Consequently, semi-decomposed sheep manure was selected for this study [16,17]. Previous research has demonstrated that the incorporation of organic fertilizers, such as bio-organic fertilizers and sheep manure, into fruit tree cultivation can mitigate the overuse of chemical fertilizers, thereby reducing environmental pollution [18,19], and applying organic fertilizers can also enhance both crop yield and soil microbial diversity [20,21]. However, researchers often attribute these improvements to the gradual accumulation of organic matter following long-term, repeated applications [22], and an increase in soil organic matter will have many effects on soil’s physical, chemical and biological properties and plant growth. At present, the short-term impacts of organic nitrogen inputs on soil microbial communities, as well as how these responses differ from those induced by inorganic nitrogen inputs, remain largely unknown. Therefore, further research focusing on the impacts of various fertilizer applications on microbial communities is essential to enhance the scientific assessment of these effects, enabling timely and effective adjustments to fertilization strategies. The purpose of this study is to (1) evaluate the effect of nitrogen reduction combined with sheep manure treatment on soil physicochemical properties; (2) elucidate the influence of nitrogen reduction with sheep manure on the diversity, abundance, and composition of bacterial and fungal communities; and (3) identify the effects of soil physicochemical properties on microbial communities, along with the primary factors driving these effects. Our results will provide a basis for the optimal fertilization of Korla fragrant pears and propose fertilization strategies that are more conducive to the ecological environment and the sustainable development of orchards.

2. Materials and Methods

2.1. Experimental Site Description

The experimental study was carried out at Awati Farm (41°40′28″ N, 86°07′12″ E) in Korla City, Xinjiang (Figure 1). The study area is 1000 m2. This region has a temperate continental climate. The mean annual temperature is approximately 11 °C, with total annual precipitation ranging from 50 to 56 mm. Maximum annual evaporation is estimated at 2800 mm. The site receives 2800 to 3000 h of sunlight annually, with total solar radiation ranging from 5700 to 6500 mJ/cm2. The effective cumulative temperature ranges from 4100 to 4400 °C, and the frost-free period lasts between 210 and 239 days. Before the start of the experiment, the soil nutrient contents in the study area were measured as follows: organic matter 20.94 g·kg−1, alkali-hydrolyzed nitrogen (AN) 62.91 mg·kg−1, available phosphorus (AP) 63.95 mg·kg−1, available potassium (AK) 226.71 mg·kg−1, and pH: 7.86.

2.2. Experimental Design

The field experiment on nitrogen fertilizer reduction combined with sheep manure was carried out with 10–12-year-old Korla fragrant pear orchard soil as the material. Plant spacing was 2 × 4 m, with a density of 1125 plants per hectare. Twenty-five trees with similar growth and no signs of pest or disease infestation were selected and marked. Five treatments were applied: no nitrogen fertilizer (N), conventional fertilization (N), a 20% reduction in nitrogen under conventional fertilization (N2), and the combination of the N2 treatment with two levels of organic fertilizer (F1 and F2) using 22,500 and 33,750 kg·hm−2 of sheep manure, respectively. The treatments were denoted as N2F1 and N2F2. Five fragrant pear trees were selected for each fertilization treatment, and a single-plant pear tree as a repeat. Sheep manure was selected from semi-rotted sheep manure (0.76%, 18.52%, 0.52%, 0.45% of total nitrogen (TN), total carbon (TC), total phosphorus (TP), and total potassium (TP), respectively) and applied in a circular furrow in the early stage of germination, in a single application. Nitrogen fertilizer was applied at 60% in the early stage of germination and 40% in the early stage of fruit expansion. Phosphate fertilizer was selected with 46% of P2O5, and potassium fertilizer was selected with 51% of K2O. All of them were applied in the early stage of germination by ring furrow application. Other field management practices were consistent with those used locally. The specific amount of fertilization is shown in the following Table 1.

2.3. Test Determination Method

2.3.1. Soil Sample Collection and Processing

In 2022, soil samples were collected from pear orchards at four growth stages: early germination (24 March), fruit setting (6 June), fruit expansion (3 August), and maturity (6 September). Three fruit trees were randomly selected each time, and soil samples were collected from 0 to 20 cm soil depth on both sides of the fertilizer furrow after removing surface litter. After preliminary crushing and mixing, the soil samples were stored as one soil sample in a self-sealing bag and then transported back to the laboratory in a fresh box with dry ice. After returning to the laboratory, the soil samples were removed from plant roots and boulders and mixed through a 2 mm sieve, and part of the soil samples were stored in a refrigerator at 4 °C for 1 week to analyze soil microbial carbon, nitrogen, and diversity; the remaining samples were air-dried indoors, passed through a 1 mm sieve, and used for soil physicochemical analysis. In this study, the mature stage was mainly selected to analyze the microorganisms.

2.3.2. Soil Physicochemical Analysis

Determination of soil physicochemical properties was conducted according to the methods of Bao [23]; pH value was determined by pH meter (Mettler Toledo, Columbus, OH, USA) (the water–soil ratio was 2.5:1). Soil total carbon, total nitrogen, organic matter, available phosphorus, and available potassium were determined by elemental analyzer (Elementar Analysensysteme GmbH, Langenselbold, Hessen, Germany), semi-micro Kjeldahl method, potassium dichromate external heating method, sodium bicarbonate extraction–molybdenum antimony sulfate anti-colorimetric method, and ammonium acetate extraction–flame photometric method, respectively. The contents of ammonium nitrogen (NH4+–N) and nitrate nitrogen (NO3−–N) were determined by 2 mol L−1 potassium chloride solution extraction and using a flow analyzer (SEAL Analytical, Mequon, WI, USA).

2.3.3. Soil Microbial Biomass

Soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) were determined by the fumigation extraction–volume fraction method and fumigation extraction–ninhydrin colorimetric method [24].
The calculation for SMBC is SMBC = Ec/kEC
where Ec represents the difference in organic carbon between fumigated and non-fumigated soil, while kEC denotes the conversion factor, assigned a value of 0.38.
The SMBN calculation is SMBN = mEmin − N
where Emin − N signifies the total nitrogen difference between fumigated and non-fumigated soil, while m represents the conversion factor, assigned a value of 5.0.

2.3.4. Measurement of Soil Microbial Communities

Soil DNA extraction, PCR amplification, and high-throughput sequencing analysis were carried out using previous research methods [25]. The detailed determination method is shown in the annex.

2.3.5. Yield Determination

In September 2022, at the mature stage of the fragrant pear, five pears were randomly selected from the top to the bottom in the four directions (east, south, west, and north) around each tree. The pears were weighed and the number of pears in each treatment was recorded. The yield was calculated using the following formula:
Yield per plant = total number of fruits per plant × single fruit weight
The total yield of 1 hm2 pear was calculated by the yield per plant.

2.4. Statistical Analysis

Data processing was conducted using Excel 2019, while SPSS 26.0 was employed to analyze the effects of different fertilization treatments on soil physicochemical properties, as well as microbial diversity. A one-way ANOVA was conducted using SPSS, with the least significant difference (LSD) method applied for multiple comparisons among treatments. A significance level of 0.05 was adopted, and the results are presented as mean ± standard error. Microbial biomass maps and yield histograms were generated using Origin 2021 software. QIIME2 (2019.4) and R language (v3.5.1) were used for analyzing species composition and performing PCoA analysis based on the Bray–Curtis distance matrix. LEfSe analysis, RDA analysis, and a Mantel test were performed on the Genescloud platform (https://www.genescloud.cn, accessed on 5 September 2024).

3. Results

3.1. Soil Physicochemical and Biological Properties

3.1.1. Soil Physicochemical Properties

The changes in soil physicochemical indices within the 0–20 cm soil layer (Table 2) were observed. Compared to the N0 treatment, the complete nitrogen treatment application significantly increased the levels of soil TC, TN, NH4+–N, NO3−–N, AN, AP, and AK, while the pH decreased by 5.38%. Compared to complete nitrogen application, the contents of TC, TN, NH4+–N, NO3−–N, AN, AP, and AK in the soil were reduced under the N2 treatment, while soil SOM and pH were increased. Notably, the reductions in TN, AN, and AP were significant, with decreases of 14.29%, 17.08%, and 14.21%, respectively. The N2F1 and N2F2 treatments showed varying degrees of increase in all indices, except for AP, compared to complete nitrogen application. In the N2F1 treatment, NH4+–N, NO3−–N, SOM, and pH increased significantly by 57.53%, 29.14%, 9.90%, and 3.17%, respectively. In the N2F2 treatment, TC, TN, NH4+–N, NO3−–N, AN, AK, SOM, and pH increased significantly by 10.97%, 10.99%, 70.37%, 78.99%, 17.72%, 8.90%, 14.51%, and 3.96%, respectively. These results suggest that a 20% nitrogen reduction combined with sheep manure (F1 and F2) significantly enhanced NH4+–N, NO3−–N, SOM, and pH.

3.1.2. Soil Biological Properties

Based on the analysis of the biological characteristics of 0–20 cm soil (Figure 2A), the soil microbial biomass carbon (SMBC) of each treatment ranged from 414.96 to 333.13 mg·kg−1. Compared with N0 treatment, SMBC in the complete nitrogen treatment increased by 7.02%. Compared with complete nitrogen application, SMBC in the N2 treatment decreased, but the difference between treatments was not significant. The SMBC of N2F1 and N2F2 treatments increased to varying degrees compared with complete nitrogen application, and the difference between treatments was significant, showing significant increases of 14.14% and 16.39% compared with complete nitrogen application, respectively. The varying trend in soil microbial biomass nitrogen (SMBN) in the 0–20 cm soil layer under different treatments is shown in Figure 2B. Compared to the N0 treatment, the complete nitrogen application significantly increased SMBN content, with a 21.22% increase. Compared to the complete nitrogen application, the SMBN content in the N2 treatment decreased significantly by 12.59%. Similarly, the N2F1 and N2F2 treatments, when compared to complete nitrogen application, both increased SMBN content, with the N2F2 treatment showing a significant improvement of 21.13%.

3.2. Soil Bacterial and Fungal Community Diversity

3.2.1. Alpha Diversity of Soil Bacteria and Fungi

Soil microbial communities subjected to different treatments were analyzed for alpha diversity with four standard metrics: the Chao1 index and Observed species index (species richness) along with Shannon and Simpson indices (diversity). These metrics were used to assess the structural characteristics of microbial communities in each treatment. It can be seen from Table 3 that in bacteria, the Chao1, Observed species, Pielou’s evenness, and Shannon and Simpson indices of complete nitrogen application treatment were lower than those of the N0 treatment, and the Chao1, Observed species, and Shannon indices were significantly different, being significantly reduced by 19.30%, 43.24%, and 4.34%, respectively. Compared with the complete nitrogen application, the Chao1, Observed species, and Shannon indices of the N2 treatment decreased, and the Chao1 and Observed species indices were significantly different from those of complete nitrogen application, being significantly reduced by 29.66% and 26.92%, respectively, compared with the complete nitrogen application. The Pielou’s evenness and Simpson indices increased compared to the complete nitrogen treatment, with the Simpson index showing a significant increase of 28.16%. There was no significant difference between Pielou’s evenness index and complete nitrogen treatment. N2F1 and N2F2 treatments showed some degree of decrease in Chao1 and Observed species indices compared to complete nitrogen application, where the Observed species indices differed significantly from the complete nitrogen application treatments with a significant decrease of 15.58% and 18.18%, respectively. The Pielou’s evenness, Shannon and Simpson indices increased compared with the complete nitrogen application treatment, among which N2F1 and N2F2 treatments differed significantly from the complete nitrogen application treatment in Pielou’s evenness and Simpson indices, which increased by 6.71% compared with the complete nitrogen application treatment. It also significantly increased by 6.71%, 5.51%, 0.41%, and 0.33%, and the N2F1 treatment was significantly different from among treatments with complete nitrogen application in terms of its Shannon index, which significantly increased by 4.44%.
In fungi, the Chao1, Observed species, Pielou’s evenness, Shannon, and Simpson indices did not differ significantly between the complete nitrogen treatment compared with the N0 treatment. Compared to the complete nitrogen application, the Chao1, Observed species, Pielou’s evenness, Shannon, and Simpson indices were reduced under the N2 treatment. Among these, the Pielou’s evenness and Shannon indices showed significant differences, decreasing by 18.58% and 21.22%, respectively. No significant differences were observed in the Chao1, Observed species, Pielou’s evenness, Shannon, or Simpson indices between the N2F1, N2F2, and complete nitrogen treatments.

3.2.2. OTU Number and β Diversity of Soil Bacteria and Fungi

A total of 37,195 bacterial OTUs were detected in the N0, N, N2, N2F1, and N2F2 treatments, out of which 310 OTUs, or 0.83% of the total, were shared (Figure 3A). The OTUs from each treatment accounted for 28.40%, 23.38%, 15.60%, 16.67%, and 15.94% of the total, respectively. In fungi, a total of 887 fungal OTUs were detected in each of the treatments N0, N, N2, N2F1, and N2F2, of which 41 OTUs, or 4.62% of the total, were shared (Figure 3B). PCoA analysis of the soil microbial community composition for the five treatments was conducted based on the Bray–Curtis distance. As shown in Figure 4, the β-diversity of bacteria (Figure 4A) and fungi (Figure 4B) along the X-axis reveals a distinct separation between the N, N2, N2F1, N2F2 treatments and the N0 treatment. This separation indicates marked variations in the composition of soil bacterial and fungal communities under different fertilization treatments.

3.3. Soil Bacterial and Fungal Microbial Community Composition

3.3.1. Analysis of Soil Bacteria and Taxonomic Composition

The bacterial phyla with relative abundance in the top 10 were selected to analyze the variations in the composition of soil bacterial communities during the growth period of scented pear orchards under each treatment of nitrogen reduction with sheep manure by taxonomic composition analysis of species composition (Figure 5). Columns represent samples, with different colors corresponding to distinct annotation information, while “other” includes all species outside the top 10. Among the bacterial phyla, Proteobacteria, Actinobacteria, and Firmicutes were dominant, with average relative abundances of 29.73%, 26.22%, and 23.03%, respectively. The relative abundances of Gemmatimonadetes, Bacteroidetes, Chloroflexi, Acidobacteria, and Deinococcus-Thermus ranged between 1% and 10%, whereas the other phyla exhibited relative abundances below 1%. Due to differences in nitrogen fertilizer application, the distribution of bacterial phyla also changed. Under complete nitrogen treatment, the relative abundances of Firmicutes, Gemmatimonadetes, Proteobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Acidobacteria, and Deinococcus-Thermus exhibited varying degrees of increase or decrease when compared to the N0 treatment. However, no significant differences were observed. Compared to complete nitrogen application, the relative abundances of Proteobacteria, Bacteroidetes, and Deinococcus-Thermus increased to varying extents in the N2, N2F1, and N2F2 treatments; among them, a marked difference was observed between the N2 treatment and complete nitrogen application, with increases of 96.79%, 562.70%, and 3255.11%, respectively. The relative abundance of Firmicutes was lower in all treatments compared to the complete nitrogen application, with a significant decrease observed in the N2F1 treatment, which was 67.40% lower than that of the complete nitrogen application. No significant differences were found between the other phyla and the complete nitrogen treatment.
Changes in soil fungal community composition were analyzed using the top 10 fungal phyla based on their relative abundance during the growth period of the pear orchard under nitrogen reduction combined with sheep manure (Figure 6). The relative abundances of Ascomycota, Basidiomycota, Mortierellomycota, Rozellomycota, Mucoromycota, and Olpidiomycota were all greater than 0.01% in each treatment. Ascomycota dominated, with an average relative abundance of 83.47% across treatments. Fungal phylum distribution changed in response to fertilizer application. Compared with the N0 treatment, the relative abundance of Basidiomycota, Rozellomycota, and Olpidiomycota increased under complete nitrogen application, while Ascomycota, Mortierellomycota, and Mucoromycota decreased. A significant difference was observed for Ascomycota compared to the N0 treatment, with a decrease of 49.70%. No significant differences were found for the other phyla compared to the N0 treatment. In addition, compared with complete nitrogen application, there was no significant difference between N2, N2F1, N2F2 treatments and complete nitrogen application.

3.3.2. LEfSe Hierarchical Tree and LDA Discriminant Results of Soil Bacteria and Fungi

In this study, intergroup comparisons using LEfSe (Bacteria: LEfSe = 4, Fungi: LEfSe = 2) was employed for inter-group comparisons to analyze species with notable variations in the relative abundance of soil microbial communities across treatments. The results (Figure 7) revealed that 40 bacterial species exhibited significant differences, with 4 in the N0 treatment, 10 in the N treatment, 16 in the N2 treatment, 6 in the N2F1 treatment, and 4 in the N2F2 treatment. The three species showing the most significant differences in the N0 treatment were Micrococcales (order), Actinobacteria (phylum), and Micrococcaceae (family). The three species with the most significant differences in the N treatment were Bacillales (order), Bacilli (class), and Planococcaceae (phylum). In the N2 treatment, the most significant differences were observed in Gammaproteobacteria (class), Oceanospirillales (order), and Halomonadaceae (family). In the N2F1 treatment, Cytophagales (order), Xanthomonadales (order), and Xanthomonadaceae (family) exhibited the most significant differences. In the N2F2 treatment, the most significant differences were found in Steroidobacterales (genus), Gemmatimonadetes (phylum), and Acidobacteria (class). The number of microbial markers of bacteria was N2 > N > N2F1 > N2F2 = N0.
A total of 30 fungal species showed significant differences (Figure 8), with 10 in the N0 treatment, 2 in the N treatment, 4 in the N2 treatment, 6 in the N2F1 treatment, and 8 in the N2F2 treatment. The N0 treatment exhibited the most notable differences in Ascomycota (phylum), Sordariomycetes (class), and Kernia (genus). In the N treatment, Ceriporia (genus) and Onygenales_fam_Incertae_sedis (family) showed the most significant differences. The three species with the most significant differences in the N2 treatment were Aspergillus (genus), Aspergillaceae (family), and Eurotiales (order). In the N2F1 treatment, Arthrographis (genus), Eremomycetaceae (family), and Dothideomycetes_ord_Incertae_sedis (family) showed the most significant differences. The N2F2 treatment exhibited the most significant differences in Onygenales (order), Gymnoascaceae (family), and Gymnascella (genus). The ranking of fungal microbial markers was N2F2 > N0 > N2F1 > N2 > N.

3.4. Correlation Analysis of Soil Environmental Factors, Microbial Community and Yield

3.4.1. Correlation Analysis Between Soil Environmental Factors and Microbial Community

The bacterial and fungal communities and soil environmental factors were analyzed. The redundancy analysis of bacteria revealed that pH and SOM significantly influenced bacterial communities, while NO3−–N had a highly significant effect on it. The first environmental principal component and the second environmental principal component of the bacterial community explained 80.71% and 8.54%, respectively (Figure 9A). Fungal redundancy analysis showed that TC, TN, and pH had significant effects on the fungal community, and AN, NO3−–N, NH4+–N, AP, AK, and SOM had extremely significant effects on the fungal community. The fungal community’s first and second environmental principal components accounted for 84.17% and 0.07% of the variation, respectively (Figure 9B).

3.4.2. Correlation Analysis Between Yield and Soil Environmental Factors

When analyzing the yield of fragrant pear in Korla, it was found that compared with the N0 treatment, the yield under the complete nitrogen application treatment was significantly higher, by 79.56%; however, compared with complete nitrogen application, both a 20% reduction in nitrogen and a 20% reduction in nitrogen with the application of the F1–F2 sheep manure treatments did not have a significant effect on the yield of the fragrant pear orchard (Figure 10A). The Mantel test results (Figure 10B) indicated that the yield of fragrant pear was significantly positively associated with TN, AN, AK, and pH and significantly positively correlated with TC.

4. Discussion

4.1. Effects of Nitrogen Reduction Combined with Sheep Manure on Soil Physicochemical Properties and Biological Characteristics

Soil nutrients are the basis of plant growth, yet excessive application of chemical fertilizers added to the soil will cause environmental pollution and increase the cost of planting. The long-term single fertilization mode of crops in the process of continuous cropping will lead to the accumulation of acid radical ions, a decrease in soil pH, and the accumulation of salt substances, which will affect the normal growth and development of plants [26]. The preferential absorption of nutrients by single crops can also lead to the imbalance of soil nutrients, thus inducing continuous cropping obstacles [27]. The effects of different nitrogen fertilizer applications and nitrogen reduction combined with sheep manure on a pear orchard’s soil’s physicochemical properties were compared in this study. The findings indicated that, relative to the N0 control, nitrogen application significantly promoted an increase in soil nutrient content but significantly reduced the soil pH value. The N2 treatment, however, significantly reduced soil TN, AN, and AP contents. Soil treated with nitrogen reduction combined with sheep manure had higher physical and chemical indices than soil treated with nitrogen fertilizer alone (except for AP). Both N2F1 and N2F2 treatments significantly increased NO3−–N, NH4+–N, SOM, and pH levels. Ding et al. [28] also found that fertilization enhanced soil concentrations of AP, AK, NN, AN, OM, TP, and TN. This beneficial effect of manure on increasing pH may be due to the fact that manure contains carbonates and bicarbonates, and organic acids containing carboxyl and phenolic hydroxyl groups can neutralize soil acidity and elevate soil pH levels [29]. However, some studies have shown that applying manure alone or in combination with chemical fertilizers did not stabilize or raise soil pH but instead led to a significant decrease, which contrasts with the findings of this study [30]. This discrepancy might be explained by variations in soil types. Wu et al. [31], in investigating the impact of reduced chemical fertilizer on the microbial community of tidal soils in the North China Plain, found higher TN and SOM contents in soils treated with a combination of organic fertilizer and fertilizer reduction than in those treated with chemical fertilizer alone. Likewise, Gao et al. [32], in studying the effects of organic and chemical fertilizers on soil characteristics and microbial communities in the North China agricultural–pastoral zone, found that SOM, TN, AN, AP, and AK contents were significantly higher in treated soils than in the control. Additionally, Han et al. [13] found that the application of organic manure increased NO3−–N, TN, AP, and AK content compared to chemical fertilizers alone. These results are similar to the results of the present study, indicating that fertilizer application can significantly improve the physicochemical properties of soil, while the application of sheep manure, as an organic fertilizer, is more conducive to the accumulation of soil nutrients.
Soil microbial mass carbon and nitrogen are important components of soil organic matter, and the level of their contents can reflect the activities of soil microorganisms and the efficiency of nutrient conversion. The results of soil biological characteristics in this study showed that nitrogen application significantly promoted the content of SMBC and SMBN in the 0–20 cm soil layer. However, after a 20% nitrogen reduction, the content of SMBN decreased compared with the complete nitrogen application, while the content of SMBC and SMBN in the soil treated with sheep manure increased to varying degrees, among which the high amount of sheep manure treatment had the most significant effect on increasing the content of SMBC and SMBN in the soil. This is primarily attributed to the provision of a substantial carbon source by sheep manure, which stimulates the proliferation of soil microorganisms and supplies key nutrients required for crop development, thereby significantly enhancing soil microbial diversity [33,34]. In addition, inorganic nitrogen contributes abundant nitrogen and increases carbon and nitrogen content in the soil, and the application of chemical fertilizers can also increase plant biomass.

4.2. Effects of Nitrogen Reduction Combined with Sheep Manure on Soil Microbial Community Diversity

The impact of nitrogen fertilization on bacterial and fungal diversity is influenced by ecosystem type, nitrogen fertilizer type, and the amount and duration of fertilization [35]. This study’s results indicate that nitrogen application significantly inhibits bacterial community richness and diversity. A 20% reduction in nitrogen, relative to complete nitrogen application, notably decreases bacterial community richness while significantly increasing its diversity. Furthermore, a 20% reduction in nitrogen combined with sheep manure (F1 and F2) significantly suppresses bacterial community richness but substantially enhances bacterial community evenness and diversity. Dai et al. [36] observed that nitrogen fertilization alone led to a significant decrease in bacterial diversity in dryland soils, whereas it enhanced bacterial diversity in anaerobic soils. Additionally, previous research has demonstrated that overuse of nitrogen fertilizers leads to soil acidification and a decline in bacterial diversity [37]. In contrast, soil organic amendments enhance biological properties, enzyme activities, and the growth and diversity of soil microbial communities [38,39]. Consequently, our findings, along with these studies, indicate that bacterial diversity’s response to nitrogen application varies depending on the test duration and the type of field.
For the fungal community, this study’s findings revealed that nitrogen application had no notable effect on richness, diversity, or evenness. However, a 20% reduction in nitrogen, relative to complete nitrogen application, significantly reduced fungal community evenness and diversity. The application of sheep manure (F1–F2) in combination with the 20% reduction in nitrogen showed no significant influence on the richness, diversity, or evenness of the fungal community. Previous investigations revealed that combining organic and inorganic fertilizers results in a smaller influence on soil fungal diversity compared to inorganic fertilizers applied on their own [28]. Han et al. [13] similarly found that different fertilizer application strategies had minimal impact on fungal abundance and diversity, which aligns with the findings of this study. Wang et al. [40] reported that fungi thrive in acidic soils, whereas the soil in the present study was weakly alkaline, which significantly inhibited fungal growth. Previous studies have also revealed that nitrogen application decreased fungal community diversity and altered their composition [41,42]. Luo et al. [43] discovered that both inorganic and organic fertilizers significantly enhanced fungal diversity, with organic fertilizer exhibiting a stronger effect. However, He et al. [44] reported that the use of culture-dependent methods and long-term application of organic fertilizers, especially manure, may reduce fungal diversity. These differences in results may be attributed to variations in methods and soil types. Different fertilization strategies can cause the migration and enrichment of soil nutrients [45], resulting in a “preference” effect that promotes the growth of specific fungal groups, thereby depleting nutrients and suppressing the growth of other groups [46].

4.3. Effects of Nitrogen Reduction Combined with Sheep Manure on Soil Microbial Community Characteristics

Soil microorganisms are essential for maintaining the soil ecosystem. The diversity and composition of soil microbial communities act as important indicators of their ecological roles [47]. Bacteria, as indicator species of the soil environment, contribute to enhancing soil structure and promoting plant growth [48]. Fungi play a crucial ecological role in soil by forming mycorrhizal associations with crops, which are highly significant for enhancing plant growth and maintaining the stability of agricultural ecosystems [49]. This experimental study shows that the dominant bacteria in the bacterial community were Proteobacteria, Actinobacteria and Firmicutes. Ali et al. [50] found that the dominant bacteria in each treatment were Proteobacteria, Acidobacteria, Actinobacteria, and Bacteroidetes in their study of the effects of paddy soil properties and microbial communities, as well as Gemmatimonadetes, Planctomycetes, Verrucomicrobian and Chloroflexi among the others. Wu et al. [31] studied the changes in microbial community in flavor-aquic soil while using a combination of chemical fertilizer reduction and organic fertilizer in the North China Plain. The dominant bacteria were Actinobacteria, Proteobacteria, Chlorophyta, and Acidobacteria. These results are similar to the results of this study, indicating that the dominant phylum of bacteria is stable in different crops and fertilization treatments, and individual differences may be caused by the differences in bacterial communities under local ecological environment conditions. In this study, nitrogen application had no significant impact on the relative abundance of bacterial phyla. However, a 20% reduction in nitrogen, compared to complete nitrogen application, significantly increased the relative abundance of Proteobacteria, Bacteroidetes, and Deinococcus-Thermus. A 20% reduction in nitrogen combined with sheep manure F1 treatment significantly reduced the relative abundance of Firmicutes. These results indicate that appropriate nitrogen levels can enhance the abundance of Proteobacteria, Bacteroidetes, and Deinococcus-Thermus. Following nitrogen reduction combined with quantitative sheep manure, the relative abundance of Firmicutes in the soil increased. This may be due to the organic matter in sheep manure, which modified the soil’s physicochemical properties and subsequently influenced the microbial community structure.
In this experiment, the dominant fungal phylum was Ascomycota, with an average relative abundance of 83.47%. Ascomycetes, which include many soil saprophytic fungi, play a key role in decomposing lignified plant debris [51]. They are also the most abundant fungi in the soil and can survive in both alkaline and acidic soils [52]. The present study demonstrated that nitrogen application significantly inhibited the relative abundance of the Ascomycota phylum, but based on complete nitrogen application, nitrogen reduction by 20% and nitrogen reduction by 20% combined with sheep manure treatments F1–F2 had no significant effect on Ascomycota, Basidiomycota, Mortierellomycota, Rozellomycota, Mucoromycota, and Olpidiomycota. In this experiment, Ascomycota was the most abundant in the non-nitrogen treatment. This condition may have created a favorable environment for Ascomycota to efficiently utilize apoplastic materials from degradable vegetation, thereby promoting rapid colony growth and reproduction. Ascomycota, Zygomycota, and Basidiomycota have been identified as the dominant fungal phyla in previous research by Ding et al. [28]. Similarly, Wu et al. [31] observed that Ascomycota accounted for an average of 90.29% of the fungal community in soil, confirming its dominance. This is similar to the relative abundance of Ascomycota in this study, indicating that Ascomycota is the dominant phylum in soil microbial fungi of different crops, and its relative abundance is relatively high.
LEfSe results showed that different fertilization methods had different types of bacteria or fungi that responded to the soil. In the bacterial community, the number of iconic species was the highest under the N2 treatment, and the number of iconic species was the highest under the N2F2 treatment in the fungi, indicating that the response of bacteria to 20% nitrogen reduction, based on complete nitrogen application, was more intense than to other treatments, and the application of sheep manure F2, based on 20% nitrogen reduction, strengthened the response of the fungal community.

4.4. Correlation Analysis Between the Yield and Soil Physical and Chemical Properties of the Microbial Community

The bacterial redundancy analysis showed that pH, SOM, and NO3−–N had significant or extremely significant effects on bacterial community. In the fungal redundancy analysis, TC, TN, AN, NH4+–N, NO3−–N, AP, AK, pH, and SOM all had significant or extremely significant effects on the fungal community. This shows that pH, SOM, and NO3−–N are the main environmental factors affecting microbial bacteria and fungal communities. Song et al. [53] reached a similar conclusion, and NO3−–N concentration also proved to be a crucial factor affecting the composition and diversity of soil bacterial communities [54]. Han et al. [13] discovered that NO3−–N, TN, EC, AP, and AK exhibited significant correlations with bacterial community composition, whereas TN, AK, and NO3−–N were strongly associated with fungal community composition during their investigation of the effects of partially replacing chemical fertilizer with organic fertilizer on soil fertility and microbial communities in newly cultivated lands in the Loess Plateau, China. The results of Ding et al. [28] also showed that soil AP and SOM content had the greatest influence on fungal community structure, while fungal diversity was mainly determined by AP, TP, TN, and soil pH. Similarly, Wu et al. [31] found that bacterial community structure was significantly correlated with SOM and TN, while fungal community structure was significantly correlated with AP, SOM, and TN. These findings are similar to the results of this study, suggesting that reducing chemical fertilizer in combination with organic fertilizer effectively boosted soil fertility, increased nutrient availability, and altered the structure of bacterial and fungal communities.
Soil nutrient content reflects the soil’s capacity to supply fertilizers, which is closely linked to the growth and yield of the fragrant pear. Numerous studies have demonstrated that different fertilization treatments influence soil nutrients, fertility, structure, and microbial communities [55,56]. Fertilization is widely regarded as a fundamental agricultural practice for improving soil fertility and crop productivity. Evidence from long-term studies suggests that organic fertilizer improves soil structure, whereas chemical fertilizer treatments result in negligible changes to soil’s quality-related attributes [57,58]. The findings of this study indicated a positive correlation between the physical and chemical indices (except pH), and the difference was significant. There was a notable positive correlation between yield and TN, AN, AK, and pH, and a significant positive correlation with TC, indicating that soil nutrients had a positive effect on crop yield. When comparing the yield changes of each fertilization, compared with the control treatment N0, nitrogen application significantly increased the yield of the fragrant pear orchard, but compared with the complete nitrogen application, the effect of 20 % nitrogen reduction or 20% nitrogen reduction combined with sheep manure treatments F1–F2 on the yield of fragrant pears was not obvious. The results showed that based on 300 kg·hm−2 nitrogen application, 20% nitrogen reduction did not exert a notable impact on the yield of pear, and the addition of sheep manure F1–F2 based on nitrogen reduction had no significant effect on the yield. Previous research has also revealed that combining chemical fertilizers with organic fertilizers can effectively lower soil bulk density and enhance soil organic matter content, though it may only slightly affect crop yield [53,59]. Zhang et al. [60] also reached the same conclusion. This may be attributed to the soil in the test area having a strong foundation of fertility. As a result, even with a reduction in nitrogen fertilizer and the application of sheep manure, the existing nutrient reserves in the soil were sufficient to support crop growth, and the short-term yield was not significantly impacted by the reduced nitrogen application [61]. Other studies have demonstrated that organic fertilizer, whether applied alone or combined with inorganic fertilizer, enhances fruit yield, quality, and nutritional value more effectively than inorganic fertilizer alone. This improvement has been attributed to the provision of diverse nutrients, improving soil physical properties, and the boost in microbial biomass through the addition of organic fertilizers [62,63]. A decrease in crop yield was observed by Olsen et al. [64] following the application of organic cow manure to acidic loam soil, which was attributed to a reduction in field capacity caused by water-repellent organic matter produced during fungal decomposition. In this study, the meadow soil’s favorable water retention properties suggest that the reduction in field capacity from sheep manure application is unlikely to be a significant factor. The same conclusion was drawn by Chalmers et al. [65], who indicated that the effect of organic nutrients on crop yield is primarily a long-term one due to their slow nutrient release. The absence of a significant increase in yield in the fragrant pear observed in this study may be attributed to its short duration. Long-term trials combining organic and nitrogen fertilizers are needed to reveal potential differences. Unlike other woody plants, economic trees require substantial energy not only for maintaining normal growth but also for fruit production. Consequently, optimal soil structure and fertility are essential for achieving stable and high fruit yields. From the perspective of short-term fertilization, the addition of inorganic N alone can rapidly increase soil nutrient effectiveness but also reduce soil microbial diversity. In contrast, N reduction with organic fertilization may be a more sustainable agricultural practice through which to reduce the contribution of chemical fertilizers. Future research should therefore aim to understand the effects of long-term organic–inorganic composite fertilization on the linkages between soil nutrient cycling and microbial processes, to forecast the relationship between soil microbial functions and crop productivity, and to lay a scientific foundation for the development of eco-friendly fertilization methods that efficiently enhance sustainable agricultural progress. Although the study’s results are based on the specific soil and climatic conditions of certain areas, similar management strategies have been successfully applied to various crops and soil types in other regions, after appropriate adjustments [66,67,68]. This indicates that the growth patterns and soil nutrient requirements of different crops share common features. The mechanism underlying the impact of Korla pear fertilization on microbial characteristics and communities is similarly relevant to other crops.

5. Conclusions

The present study showed that nitrogen application promoted soil physical and chemical indicators and SMBC and SMBN contents but significantly suppressed bacterial community richness and diversity. Nitrogen reduction based on complete nitrogen application significantly reduced individual physical and chemical indices and suppressed bacterial community richness as well as the evenness and diversity of fungal communities, but bacterial diversity was significantly increased. Nitrogen reduction with sheep manure significantly increased NO3−–N, NH4+–N, SOM, pH, and soil SMBC and SMBN contents, with N2F2 treatment having the most significant effect on SMBC and SMBN contents. The sheep manure treatment also significantly promoted bacterial community uniformity and diversity but significantly suppressed bacterial community richness. Soil pH, NO3−–N, and SOM were important environmental factors affecting the level of bacterial and fungal community gates. In addition, nitrogen application significantly enhanced the yield of fragrant pear orchards, while nitrogen reduction and nitrogen reduction with sheep manure treatments caused no significant change in yield compared to complete nitrogen application. In conclusion, a 20% N reduction based on complete N application (300 kg·hm−2) together with a sheep manure application of 22500~33750 kg·hm−2 in 10–12-year-old Korla pear orchards is beneficial to the maintenance of the stability and health of soil microbiota in pear orchards.

Author Contributions

W.X., Z.C., B.D. and X.S. conceived and designed the experiment. W.X., W.L., L.Y. and J.L. conducted experiments and analyzed the data. W.X., Z.C. and B.D. wrote the paper. All authors have read and agreed to the published version of the manuscript.

Funding

This study was supported by the National Natural Science Foundation of China (32360802, 31960639), the Key Laboratory of the Xinjiang Uygur Autonomous Region (2021D04005), the Xinjiang Uygur Autonomous Region “Agriculture, Rural Areas and Farmers” Backbone Talents Training Project (2022SNGGGCC017), and Xinjiang Forest Fruit Industry Technology System—Soil Fertility and Cultivation (XJLGCYJSTX05-2024-03).

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding authors.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Overview of the study area.
Figure 1. Overview of the study area.
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Figure 2. Effects of nitrogen reduction combined with sheep manure on (A) soil microbial biomass carbon(SMBC) and (B) soil microbial biomass nitrogen (SMBN) content. The error bars indicate standard errors. Different lowercase letters represent significant differences between treatments (p < 0.05).
Figure 2. Effects of nitrogen reduction combined with sheep manure on (A) soil microbial biomass carbon(SMBC) and (B) soil microbial biomass nitrogen (SMBN) content. The error bars indicate standard errors. Different lowercase letters represent significant differences between treatments (p < 0.05).
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Figure 3. Venn diagrams of (A) bacterial OTUs’ richness and (B) fungal OTUs’ richness.
Figure 3. Venn diagrams of (A) bacterial OTUs’ richness and (B) fungal OTUs’ richness.
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Figure 4. Effects of different fertilization treatments on the β diversity of the soil bacterial (A) and fungal (B) community (PCoA analysis).
Figure 4. Effects of different fertilization treatments on the β diversity of the soil bacterial (A) and fungal (B) community (PCoA analysis).
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Figure 5. Distribution of the top 10 soil bacterial phyla (A,B) in different treatments.
Figure 5. Distribution of the top 10 soil bacterial phyla (A,B) in different treatments.
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Figure 6. Distribution of the top 10 soil fungal phyla (A,B) in different treatments.
Figure 6. Distribution of the top 10 soil fungal phyla (A,B) in different treatments.
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Figure 7. LEfSe difference analysis of soil bacterial community. (A) Taxonomic representation of important variations among groups shown in the cladogram. (B) LDA score histogram.
Figure 7. LEfSe difference analysis of soil bacterial community. (A) Taxonomic representation of important variations among groups shown in the cladogram. (B) LDA score histogram.
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Figure 8. LEfSe difference analysis of soil fungal community. (A) Taxonomic representation of important variations among groups shown in the cladogram. (B) LDA score histogram.
Figure 8. LEfSe difference analysis of soil fungal community. (A) Taxonomic representation of important variations among groups shown in the cladogram. (B) LDA score histogram.
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Figure 9. RDA redundancy analysis of soil environmental factors and bacterial (A) and fungal (B) community diversity.
Figure 9. RDA redundancy analysis of soil environmental factors and bacterial (A) and fungal (B) community diversity.
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Figure 10. Yield of Korla fragrant pear (A) and correlation analysis between yield and soil physical and chemical properties (B). The correlation strength is represented by the heat map’s color gradient; darker blue indicates a stronger negative correlation, while red signifies a stronger positive correlation. * represents significant correlation (p < 0.05), **, *** represents extremely significant correlation (p < 0.01). The thickness of the line between the yield and the environmental factors indicates the size of the correlation; the thicker the line, the stronger the correlation, and vice versa. The color of the connection between the node and the environmental factor represents the p-value.
Figure 10. Yield of Korla fragrant pear (A) and correlation analysis between yield and soil physical and chemical properties (B). The correlation strength is represented by the heat map’s color gradient; darker blue indicates a stronger negative correlation, while red signifies a stronger positive correlation. * represents significant correlation (p < 0.05), **, *** represents extremely significant correlation (p < 0.01). The thickness of the line between the yield and the environmental factors indicates the size of the correlation; the thicker the line, the stronger the correlation, and vice versa. The color of the connection between the node and the environmental factor represents the p-value.
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Table 1. Experimental program of different fertilizer treatments.
Table 1. Experimental program of different fertilizer treatments.
TreatmentsFertilization Dosage (kg·hm−2)Fertilization Dosage (kg·plant−1)
NP2O5K2OSheep ManureNP2O5K2OSheep Manure
1N0030075000.2670.0670
2N3003007500.2670.2670.0670
3N22403007500.2130.2670.0670
4N2F12403007522,5000.2130.2670.06720
5N2F22403007533,7500.2130.2670.06730
Table 2. Variations in soil physicochemical characteristics across different fertilization treatments.
Table 2. Variations in soil physicochemical characteristics across different fertilization treatments.
TreatmentTCTNNO3−-NNH4+-NANAPAKSOMpH
N017.65 ± 0.50 c0.67 ± 0.02 d33.48 ± 1.09 c4.19 ± 0.27 d41.18 ± 1.63 d61.04 ± 1.02 b197.67 ± 4.33 c20.08 ± 0.41 c8.00 + 0.02 a
N19.79 ± 0.29 b0.91 ± 0.01 b39.25 ± 1.85 b6.52 ± 0.20 c62.25 ± 1.46 b69.66 ± 2.63 a221.00 ± 4.51 b21.02 ± 0.35 bc7.57 + 0.04 c
N219.29 ± 0.50 b0.78 ± 0.03 c39.23 ± 2.30 b5.79 ± 0.33 c51.62 ± 1.98 c59.76 ± 2.16 b217.33 ± 2.73 b21.15 ± 0.19 b7.62 + 0.01 c
N2F120.47 ± 0.59 ab0.93 ± 0.01 ab61.83 ± 0.99 a8.42 ± 0.43 b66.05 ± 1.00 b65.10 ± 2.52 ab230.00 ± 2.08 ab23.10 ± 0.16 a7.81 + 0.03 b
N2F221.96 ± 0.28 a1.01 ± 0.04 a66.87 ± 0.57 a11.67 ± 0.60 a73.28 ± 1.19 a69.43 ± 0.35 a240.67 ± 4.91 a24.07 ± 0.25 a7.87 + 0.03 b
Note: TC: total carbon; TN: total nitrogen; SOC: soil organic carbon; NO3−–N: nitrate nitrogen; NH4+–N: ammonium nitrogen; AN: alkaline hydrolysis nitrogen; AP: effective phosphorus; AK: immediate potassium. “±” indicates standard errors, different lowercase letters represent significant differences between treatments (p < 0.05), and the following tables and figures are the same.
Table 3. Effects of different fertilization treatments on the diversity and richness of soil bacterial and fungal microbial communities.
Table 3. Effects of different fertilization treatments on the diversity and richness of soil bacterial and fungal microbial communities.
TreatmentChao1Observed_SpeciesPielou_eShannonSimpson
BacteriaN06450.95 ± 174.51 a5361.80 ± 114.37a0.855 ± 0.007 bc10.59 ± 0.11 a0.9961 ± 0.0008 bc
N5205.87 ± 130.23 b4474.67 ± 100.77 b0.835 ± 0.012 c10.13 ± 0.16 b0.9943 ± 0.0009 c
N23661.74 ± 129.12 c3269.87 ± 101.31 c0.862 ± 0.014 abc10.06 ± 0.14 b0.9971 ± 0.0008 ab
N2F14234.44 ± 312.26 bc3777.50 ± 305.04 c0.891 ± 0.002 a10.58 ± 0.09 a0.9984 ± 0.0001 a
N2F24322.9 ± 488.34 bc3661.27 ± 274.73 c0.881 ± 0.009 ab10.42 ± 0.10 ab0.9976 ± 0.0003 ab
FungiN0189.45 ± 19.72 ab186.53 ± 18.98 ab0.615 ± 0.054 bc4.64 ± 0.47 a0.8901 ± 0.0553 ab
N185.53 ± 24.54 ab183.67 ± 23.47 ab0.635 ± 0.005 ab4.76 ± 0.14 a0.9171 ± 0.0083 ab
N2157.17 ± 14.05 b155.20 ± 13.56 b0.517 ± 0.021 c3.75 ± 0.14 b0.8122 ± 0.0286 b
N2F1241.75 ± 18.64 a238.47 ± 18.89 a0.623 ± 0.011 ab4.92 ± 0.15 a0.9081 ± 0.0169 ab
N2F2196.16 ± 27.34 ab195.23 ± 27.28 ab0.719 ± 0.026 a5.44 ± 0.12 a0.9523 ± 0.0034a
“±” indicates standard errors, different lowercase letters represent significant differences between treatments (p < 0.05).
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Xie, W.; Shen, X.; Li, W.; Yan, L.; Li, J.; Ding, B.; Chai, Z. The Effects of Nitrogen Reduction and Sheep Manure Incorporation on the Soil Characteristics and Microbial Community of Korla Fragrant Pear Orchards. Agronomy 2025, 15, 545. https://doi.org/10.3390/agronomy15030545

AMA Style

Xie W, Shen X, Li W, Yan L, Li J, Ding B, Chai Z. The Effects of Nitrogen Reduction and Sheep Manure Incorporation on the Soil Characteristics and Microbial Community of Korla Fragrant Pear Orchards. Agronomy. 2025; 15(3):545. https://doi.org/10.3390/agronomy15030545

Chicago/Turabian Style

Xie, Wenge, Xing Shen, Wei Li, Linsen Yan, Jie Li, Bangxin Ding, and Zhongping Chai. 2025. "The Effects of Nitrogen Reduction and Sheep Manure Incorporation on the Soil Characteristics and Microbial Community of Korla Fragrant Pear Orchards" Agronomy 15, no. 3: 545. https://doi.org/10.3390/agronomy15030545

APA Style

Xie, W., Shen, X., Li, W., Yan, L., Li, J., Ding, B., & Chai, Z. (2025). The Effects of Nitrogen Reduction and Sheep Manure Incorporation on the Soil Characteristics and Microbial Community of Korla Fragrant Pear Orchards. Agronomy, 15(3), 545. https://doi.org/10.3390/agronomy15030545

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