The field experiment was conducted during the 2023 growing season at the National Soil Quality Observation and Research Station of Aksu, located in the agricultural region of Baicheng County, Xinjiang (41°11’N, 80°15’E)(Figure 1). The experimental site is characterized by typical brown desert soil (Haplic Calcisols, FAO classification) with a sandy loam texture and moderate fertility. The region has a cold desert climate, exhibiting marked diurnal temperature variations, with the following mean annual climatic parameters: mean temperature 7.6 °C, maximum temperature 38.3 °C, minimum temperature -28.0 °C, frost-free period 148 days, annual sunshine duration of 2,789.7 hours, and annual precipitation of 171.1 mm. The station is equipped with comprehensive irrigation networks and standardized experimental plots, providing essential infrastructure for controlled experiments in maize cultivation research.

Soil samples were collected from the National Soil Quality Observation and Experiment Station in Aksu (41°10’N, 80°14’E), a long-term experimental site under zero-fertilizer management since 2020. The brown desert soil had a sandy clay loam texture. Composite samples were collected from two distinct layers—the surface tillage horizon (0–20 cm) and the subsurface layer (20–90 cm)—using stainless steel augers. After air-drying at ambient temperature (25 °C) and sieving through a 2-mm mesh, the homogenized subsamples were stored in polyethylene containers until analysis (Bian et al., 2024; Bian et al., 2025). Basic physicochemical parameters, including bulk density, pH, and cation exchange capacity, are provided in Table 1.

The experimental maize variety was “Tianyu 303,” provided by Xinjiang Tianyu Co., Ltd. (Xinjiang, China). 15N-labeled urea (10.24% abundance) was used as the nitrogen fertilizer, purchased from Shanghai Chemical Research Institute (Shanghai, China). Phosphorus and potassium fertilizers were sourced from superphosphate (P₂O₅:45%) and potassium sulfate (K₂O:50%), respectively. The micro-nano aeration oxygenation equipment used was a “B&W” micro-nano bubble generator (Honshu (Beijing) New Technology Promotion Co., Ltd., Beijing, China), which produces micro-nano bubble water. Its operating parameters were: working pressure, 0.015 MPa; and intake flow rate, 1.5 L·min^-¹. The oxygen supply device was a YUyue YU300-type oxygen generator (manufactured by Jiangsu Yuyue Medical Equipment Co., Ltd., Jiangsu, China), with an oxygen flow rate range of 1–5 L·min^-¹.

The soil column cultivation experiment was conducted using a randomized complete block design with a factorial arrangement(Figure 1D). Phosphorus (P₂O₅) application rates included four levels: P0: 0 kg ha^-¹ (control), PL: 86 kg ha^-¹, PM: 172 kg ha^-¹, and PH: 258 kg ha^-¹,Among these, PM denotes the recommended rate of phosphorus fertilizer application in local maize production, while PL and PH represent 50% reduction and 50% increase relative to the recommended rate, respectively. corresponding to dry soil mass-based application rates of 0, 0.028, 0.056, and 0.082 g P kg^-¹ soil, respectively. Nitrogen fertilization (Urea-¹⁵N) was applied via flood irrigation in three split doses: 30% at sowing, 30% at the late vegetative stage, and 40% at the reproductive stage. Oxygenation treatments consisted of two levels: C: Control (ambient aeration) and W: Micro-nano aeration oxygenation (WP). These factors formed a 4×2 factorial design, resulting in eight experimental treatments, each replicated six times, with column positions randomized and maintained throughout the growth cycle. The specific meanings of each abbreviation in this article are shown in Table 2.

This study employed the soil column cultivation approach. To minimize interference from external environmental factors, PVC pipes (inner diameter: 25 cm; height: 100 cm) were used and buried in the soil. The upper end was positioned 5 cm above ground level to prevent inflow of rainfall-induced surface runoff, while the lower end remained unsealed, maintaining direct contact with the natural soil. Each soil column was filled with 50 kg of dry soil in two layers: the 30–90 cm layer was collected from the 30–90 cm soil depth in the field, and the 0–30 cm layer was taken from the field plough layer (0–30 cm) (Figure 2). The 0–30 cm soil was thoroughly mixed with fertilizer before filling. After each filling step, the soil was watered and compacted to simulate natural field cultivation conditions.

Uniformly sized “Tianyu 303” maize seeds were selected. Sowing was performed manually via spot sowing on May 1, 2023, with a sowing depth of 2 cm and 4 seeds planted per soil column.

Soil sampling was conducted immediately after harvest (October 1, 2023) using stainless steel augers for stratified sampling from soil columns. Five depth intervals were sampled systematically: 0–15, 15–30, 30–50, 50–70, and 70–90 cm. Composite samples from each treatment were homogenized using the quartering method to ensure spatial representativeness. Post-collection protocols included: (i) immediate storage in sterile polyethylene bags; (ii) cryogenic preservation with dry ice during transport; and (iii) long-term cryopreservation at -80 °C to stabilize extracellular enzyme activities and microbial community structure. All post-processing procedures were performed under laminar flow hoods with triple alcohol sterilization between samples. These protocols minimized cross-contamination risks while preserving soil physicochemical integrity for subsequent metagenomic and enzymatic analyses.

The total phosphorus content of the plants was determined by the H2SO4 digestion - molybdenum-antimony ascorbate colorimetric method. The available phosphorus in the soil was determined by the molybdenum-antimony colorimetric method using air-dried soil that had passed through an 18-mesh sieve and was extracted with a 0.5 mol/L sodium bicarbonate solution (Sinoppharmaceutical Superior Grade Pure) (liquid-soil ratio 10:1).The total phosphorus content in the soil was determined by digestion with H2SO4-HClO4 and using the molybdenum-antimony colorimetric resistance method.

Six maize plants were selected from each treatment for indoor assessment. Grains were naturally air-dried to a moisture content of approximately 12.5%. Maize yield and its components were determined, including the number of cobs per plant, rows per cob, and grains per row. After threshing, total grain weight and 100-grain weight were measured.

At the maturity stage, soil samples from the 0–15 cm and 15–30 cm layers were collected from six soil columns per treatment. Soil sucrase activity was determined using the 3,5-dinitrosalicylic acid (DNS) colorimetric method. Soil urease activity was assayed via the indophenol blue colorimetric method. Soil phosphatase activity was measured using the sodium p-nitrophenyl phosphate colorimetric method.

Primers 338F(5’-ACTCCTACGGGAGGCAGCA-3’) and 806R(5’-GGACTACHVGGGTWTCTAAT-3’) were used for PCR amplification of the V3-V4 regions of 16S rRNA in rhizosphere soil bacteria; Primers ITS5F(5’-GGAAGTAAAAGTCGTAA CAAGG-3’) and ITS1R(5’-GCTGCGTTCT TCATCGATGC-3’) were used for PCR amplification of the ITS1 region of fungi, and the amplification system was (25µl): Reaction buffer (5×) 5µl, GC buffer (5×) 4 µl, 2.5 mm DNA TPS 2µl, forward and reverse primers (10 mm) 1µl each, DNA template 2µl, Q5DNA high-fidelity polymerase 0.25 µl and ddH2O 20µl. The amplification procedure is as follows: pre-denaturation at 95 °C for 2 minutes, denaturation at 98 °C for 15 seconds, annealing at 55 °C for 30 seconds, extension at 72 °C for 30 seconds, 25–30 cycles, and finally extension at 72 °C for 5 minutes (Chen et al., 2018). to quality control of the original sequencing sequence, Use FLASH (Magoč and Salzberg, 2023)software according to the degree of overlap between read spliced into tags; Then, these original labels were filtered using trimmi software (version 0.33) to obtain high-quality labels. Using UPARSE software (Edgar, 2013), according to 97% (Liu et al., 2019) the similarity of sequence of OTU clustering, Extract non-repetitive sequences from the optimized sequence and remove single sequences without repetitions. OTU clustering was performed on non-repetitive sequences (excluding single sequences) with a 97% similarity. Chimeras were removed during the clustering process to obtain representative OTU sequences. map all the optimized sequences to the OTU representative sequences and select the sequences with a similarity of more than 97% to the OTU representative sequences. After each sample of bacteria and fungi was divided, the analysis of microbial diversity and community composition was conducted.

Under micro-nano aeration oxygenation conditions, soil phosphorus transformation and utilization were promoted, effectively mitigating the adverse impacts of soil phosphorus loss on maize growth. Phosphorus distribution patterns across maize plant organs are illustrated in Figure 2A. Organ-specific phosphorus concentrations ranked in descending order: grains > roots > stems > leaves > cobs > bracts, with grains exhibiting the highest phosphorus accumulation and bracts the lowest. Oxygen-enriched phosphorus management (WPM) achieved optimal phosphorus concentrations in all examined organs. Comparative analysis revealed substantial enhancements under WPM treatment compared to non-oxygenated phosphorus treatments (CP0, CPL, CPM, CPH). Specifically, grain phosphorus concentrations increased by 180.6%, 128.7%, 14.9%, and 62.0% relative to CP0, CPL, CPM, and CPH treatments, respectively, while bracts showed respective increments of 103.7%, 32.6%, 18.8%, and 32.6%. These findings demonstrate that oxygen-coupled phosphorus application significantly improves phosphorus assimilation across maize organs, with WPM treatment exerting the most pronounced effect on phosphorus biofortification.

Soil available phosphorus displayed a vertical decreasing trend with increasing soil depth across all phosphorus treatments (Figure 2B). Comparative analysis indicated that moderate phosphorus application (PM) maintained the highest available phosphorus levels among the tested gradients, whereas high phosphorus treatment (PH) exhibited reduced accumulation efficiency. This confirms that optimized phosphorus application gradients enhance soil phosphorus bioavailability. Notably, the WPM treatment achieved superior phosphorus retention capacity, significantly outperforming other treatments in sustaining elevated available phosphorus concentrations throughout the soil profile (Table 3).

Micro-nano aeration oxygenation irrigation (WP) significantly enhances the activities of soil alkaline protease, alkaline phosphatase, and urease, while also exerting a stimulatory effect on soil microbial activity (Figure 3). The activities of alkaline protease, alkaline phosphatase, and urease varied significantly with irrigation method (P < 0.001). However, the interaction between irrigation method and Column P gradient was not statistically significant. Alkaline protease activity was significantly correlated with Column P gradient (P < 0.05), whereas alkaline phosphatase and urease activities showed stronger correlations (P < 0.001 and P < 0.01, respectively) (Table 4). Under oxygenation treatment, alkaline phosphatase activity increased with Column P gradient, peaking at the medium phosphorus level (PM). Specifically, the oxygenated medium phosphorus treatment (WPM) increased alkaline phosphatase activity by 43.56%, 25.42%, 22.25%, and 23.30% compared to non-oxygenated treatments (CP0, CPL, CPM, CPH), respectively. These results indicate that oxygenation combined with phosphorus application effectively enhances soil enzyme activity.

Analysis of bacterial and fungal richness indices (ACE and Chao1) revealed that oxygenation treatment significantly increased richness compared to conventional irrigation (Figure 4A-D). With increasing phosphorus application, richness indices increased in both conventional and oxygenation treatments. Notably, richness indices in oxygenated phosphorus treatments (WPL, WPM, WPH) were significantly higher than in the non-oxygenated, phosphorus-free treatment (WP0). Among these, WPM showed the highest richness. Specifically, fungal Chao1 richness in WPM was 22.1%, 19.3%, 7.83%, and 11.4% higher than in CP0, CPL, CPM, and CPH, respectively. For ACE, WPM was 22.2%, 23.8%, 11.4%, and 13.5% higher than CP0, CPL, CPM, and CPH, respectively. These results indicate that oxygenated phosphorus application significantly enhances fungal and bacterial richness, with WPM having the most pronounced effect.

To visualize microbial community composition, the top 10 most abundant taxa were selected for display (Figure 4E, F), with remaining taxa grouped as “Others.” At the phylum level, Vicinamibacteria, Alphaproteobacteria, and Gammaproteobacteria were the dominant bacterial taxa, while Sordariomycetes, Mortierellomycetes, and Dothideomycetes were the dominant fungal taxa. Microbial abundance in both non-oxygenated (C) and oxygenated (W) groups increased with Column P gradient, peaking at medium phosphorus (PM) and slightly decreasing at high phosphorus (PH). This indicates that under oxygenation, optimal phosphorus application effectively enhances microbial richness and diversity.

Micro-nano aeration oxygenation (WP) positively impacts maize yield and its yield components (Figure 5F). Oxygenated irrigation combined with phosphorus application significantly affected maize yield and 100-grain weight (p<0.001) (Table 5). Across all Column P gradients, yield and 100-grain weight under oxygenated conditions were significantly higher than those under non-oxygenated treatments (p<0.05). Under both oxygenated and non-oxygenated conditions, maize yield increased initially and then decreased with increasing phosphorus levels, peaking at the medium Column P gradient (PM). Specifically, the yield in the oxygenated medium phosphorus treatment (WPM) was 57.7%, 35.3%, 25.6%, and 27.9% higher than those in non-oxygenated treatments (CP0, CPL, CPM, and CPH), respectively. Phosphorus application significantly increased maize yield, with maximum yields observed at the medium phosphorus level (PM): 1,104.93 kg/hm² for non-oxygenated medium phosphorus (CPM) and 1,387.04 kg/hm² for oxygenated medium phosphorus (WPM).

Dry matter accumulation in maize organs under different treatments is shown in Figure 5. Oxygenated irrigation significantly increased the dry matter content of all maize organs (p<0.05). Under both oxygenated and non-oxygenated conditions, dry matter accumulation in each organ increased initially and then decreased with increasing phosphorus levels, reaching maximum values at the medium Column P gradient (PM). Notably, the grain dry weight in the WPM treatment was 56.5%, 33.9%, 24.5%, and 26.9% higher than those in CP0, CPL, CPM, and CPH, respectively. The combination of oxygenated irrigation and optimal phosphorus application effectively improved overall dry matter accumulation in maize.

To further explore relationships between microbial abundance, yield, and related indicators, correlation analysis was performed to examine these variables (Figure 6). For correlations between yield components and biomass indicators, bare tip length showed negative correlations with all measured indicators, with the strongest negative correlations observed for spike axis dry weight, grain dry weight, leaf dry weight, grain row number, grains per spike, spike length, and yield (p<0.05). Yield was significantly positively correlated with all other measured indicators, indicating that favorable maize growth status is critical for yield improvement.

In correlation analyses between bacterial/fungal species richness and maize yield components, bacterial and fungal richness exerted a highly significant positive effect on maize yield (p<0.01), suggesting that a favorable microbial environment promotes maize yield. Notably, bacterial richness was negatively correlated with root dry weight, though this relationship was not statistically significant (p>0.05), indicating an independent association between root dry weight and bacterial richness in this study. Collectively, these results demonstrate that microbial richness significantly influences maize yield and biomass.

Heat map analysis revealed that maize yield and plant biomass are interdependent and mutually reinforcing. Network graph analysis further indicated that microbial richness exhibits strong correlations with maize yield, with consistent trends observed. Thus, high microbial community richness is an important factor promoting maize yield.

The movement of phosphorus in soil is primarily governed by convection and adsorption mechanisms, and its efficiency is influenced by soil microorganisms (Stackebrandt and Note, 1994) and enzyme activity (Guo et al., 2023)Our team’s previous research has demonstrated that irrigation methods and Column P gradients significantly affect soil enzyme activity, thereby influencing phosphorus conversion efficiency (Bian et al., 2024; Bian et al., 2025). For instance, micro-nano aeration oxygenation (WP) significantly enhanced the activities of alkaline phosphatase, alkaline protease, and urease in the 0–15 cm soil layer. This indicates that WP improves the soil aerobic microbial environment, promoting microbial proliferation (Zhao et al., 2023; Zhou L. et al., 2023). Increased aerobic microbial activity accelerates organic matter decomposition and nutrient release (Wang J. et al., 2023; Zhou Q. et al., 2023), thereby facilitating the conversion of organic phosphorus to inorganic phosphorus and improving soil quality (Zhou et al., 2022; Zhang et al., 2023). This process supports normal crop growth and enhances phosphorus absorption efficiency. Our findings are consistent with previous studies and further confirm that under water scarcity and low phosphorus conditions, WP treatment remains effective in promoting plant phosphorus uptake and utilization (Liu et al., 2023). Additionally, our research highlights that different phosphorus application strategies significantly influence soil phosphorus mobility and availability. Excessive phosphorus application may lead to phosphorus accumulation and fixation (Urlić et al., 2023), reducing its utilization efficiency (Chen et al., 2025). In contrast, moderate phosphorus application combined with micro-nano bubble drip irrigation can prevent excessive phosphorus accumulation, maintain high phosphorus availability, and ensure efficient plant phosphorus absorption and utilization (Khan A. et al., 2023). These results corroborate our findings and underscore the importance of optimizing phosphorus application rates and irrigation methods to enhance soil phosphorus efficiency and crop yields.

Compared with the untreated control group (CP0), various irrigation treatments induced significant differences in bacterial abundance. Bacterial abundance increased markedly with increasing Column P gradient; notably, in the oxygenated medium phosphorus treatment (WPM), bacterial abundance was approximately 22.15% higher than in CP0 (Han et al., 2022). demonstrated that micro-nano aeration oxygenation (WP) significantly enhanced the richness and diversity of soil microorganisms while altering their community structure. By increasing soil oxygen content via micro-nano aeration intervention, the proliferation of oxygen-adapted microbial species was promoted (Niu et al., 2016; Sun et al., 2018), consequently inducing shifts in microbial community composition (Zhou et al., 2019). In this study, all top 10 most abundant fungal taxa were aerobic. Among bacteria, all dominant taxa were aerobic except for the anaerobic groups Blastocatellia, Anaerolineae, and Bacteroidia. Notably, these three anaerobic groups ranked 6th, 8th, and 9th, respectively, among the top 10 most abundant taxa. Correspondingly, under micro-nano aeration oxygenation (WP), the abundance of these three anaerobic groups was lower than in non-oxygenated treatments, consistent with (Chen et al., 2023). However, some studies have reported that micro-nano bubble oxygenated water application in tomato experiments significantly reduced rhizosphere microbial diversity. These discrepancies may be due to differences in oxygen content and require further investigation.

This study investigated the comparative effects of micro-nano aeration oxygenation treatment (WP) and conventional treatment (CP) on maize yield. Micro-nano aeration oxygenation irrigation is widely recognized for enhancing crop yield by improving the soil root zone environment and promoting crop water and fertilizer uptake (Du et al., 2024). Under identical Column P gradients, micro-nano bubble oxygenation treatment significantly increased maize yield. Phosphorus is a critical resource for crop production (Ouyang et al., 2023). In this study, WP treatment significantly increased maize 100-grain weight, grain yield, and biomass. Specifically, under the medium phosphorus (PM) treatment with WP (WPM), the positive impact of Column P gradient on maize yield and biomass increased progressively with phosphorus levels, whereas the high phosphorus treatment exhibited diminishing returns. This aligns with previous findings (Amanullah and Khattak, 2009; Erel et al., 2013; Jorfi et al., 2022; Lopes Sobrinho et al., 2024). Phosphorus application significantly enhances maize grain weight and yield; however, exceeding a critical phosphorus application threshold reduces grain number, grain weight, and individual plant yield. This may result from excessive phosphorus fertilizer inhibiting maize uptake of other essential elements (Erel et al., 2016). Additionally, residual soil phosphorus can bind with minerals such as calcium and magnesium, which may exacerbate soil compaction. This is also the focus of our future research, as we aim to increase or overcome the phosphorus application threshold for maize.

The current study provides preliminary evidence for the synergistic benefits of micro-nano aeration oxygenation and optimized phosphorus management on maize yield and soil microbial health in Xinjiang’s arid agricultural system. However, its scope is limited to small-scale soil column experiments and a single crop type, necessitating further research to validate scalability, adaptability, and long-term sustainability across diverse agricultural contexts. Our team proposes the following future plans: