No-till and nitrogen management improve soybean yield by increasing the net photosynthetic rate in an arid area of northwest China

No-till (NT) farming minimizes disturbance to agricultural ecosystems and regulates the water cycle in dryland agriculture. This study investigated the interactive effects of tillage practices and nitrogen (N) application on soybean (Glycine max L.) photosynthesis and yield to optimize N management in NT systems. Field experiments (2023–2024) in Shihezi, Xinjiang, employed a split-plot design with tillage (conventional tillage, CT; no-till, NT) as main plots and N rates (0, 105, 150, 195 kg N ha^-¹; denoted N0, N1, N2, N3) as subplots, generating eight treatments (CTN0, CTN1, CTN2, CTN3, NTN0, NTN1, NTN2, NTN3). The NTN2 system significantly increased soil water storage (SWS) and soil total nitrogen (STN) relative to NTN0 (P < 0.05), enhanced soybean leaf area index (LAI) during R4-R6 stages, and improved SPAD values, net photosynthetic rate (Pn), and stomatal conductance (Gs), ultimately boosting grain yield (GY) by 75.7–83.4% versus NTN0 (P < 0.05). Crucially, N2 application mitigated tillage-induced constraints, enabling NT to achieve yields comparable to CTN2 (P > 0.05). Thus, integrating no-till with 150 kg N ha^-¹ optimizes soybean productivity and resource efficiency in arid northwestern China.

1 Introduction

Improving soybean (Glycine max L.) yield is a primary agricultural goal, achieved through breeding, dense planting, optimized cultivation, and rational fertilization (De Notaris et al., 2019; Franco-Luesma et al., 2025; Seepaul et al., 2023). Conventional tillage temporarily reduces soil compaction and enhances root growth (Hu et al., 2023; Piao et al., 2019; Vizioli et al., 2021), but long-term use depletes soil nutrients and exacerbates water evaporation in semi-arid regions (Hati et al., 2021; Kang et al., 2023). No-till (NT) systems minimize soil disturbance, increase aggregate stability, and reduce erosion (Foloni et al., 2023; Zhang et al., 2021), while improving microbial-mediated nitrogen cycling (Li et al., 2023). However, prolonged NT may elevate surface compaction and nutrient stratification, restricting root function (Dai et al., 2021).

Yield formation depends on cultivation practices and environmental factors (e.g., water, nitrogen, temperature). Water stress suppresses dry matter accumulation, root vitality, and photosynthesis, whereas adequate soil moisture delays leaf senescence, increases LAI, and elevates chlorophyll content and photosynthetic rates (Wang et al., 2023, 2024). Crop responses to water stress are nitrogen-dependent (Zhou and Oosterhuis, 2012): nitrogen promotes chlorophyll synthesis and LAI expansion (Bassi et al., 2018). Optimal nitrogen application enhances photosynthesis and WUE (Guo et al., 2021; Yue et al., 2022), but excess nitrogen inhibits grain filling and induces nitrogen loss (Li X, et al., 2024; Zhang W, et al., 2020). Consequently, optimizing nitrogen fertilizer application emerges as a pivotal strategy for ensuring soil fertility and increasing crop yield (Suarez-Tapia et al., 2018). Crucially, nitrogen stability varies with tillage practices, potentially disrupting leaf nitrogen allocation and photosynthetic development (Majrashi et al., 2023; Zhang et al., 2023).

While NT with nitrogen fertilization elevates yields (Fernández-Ortega et al., 2023; Sainju et al., 2021), its physiological basis—particularly the synergy between soil water-nitrogen dynamics and photosynthetic parameters—is poorly understood. Soil water and nitrogen availability are closely associated with crop growth and linked to aboveground photosynthesis (Lamptey et al., 2017; Wang et al., 2013). We posit that NT-nitrogen integration conserves soil water, improves nitrogen availability, and augments LAI, SPAD, and photosynthetic capacity, ultimately increasing yield. This study examines NT-nitrogen interactions under semi-arid irrigation to: (i) determine effects on soybean photosynthetic parameters; (ii) establish relationships among soil water-nitrogen dynamics, photosynthesis, and yield; (iii) inform soybean and nitrogen management in northwest China’s arid oasis systems.

2 Materials and methods

2.1 Overview of the study area

The experiment was conducted at the Shihezi University Experimental Station (44°18′N, 86°03′E) from 2023 to 2024. The site is located at an elevation of 435 m, with a mean annual precipitation of 208 mm and mean annual potential evaporation of 1,660 mm. The region has a temperate continental arid climate, characterized by limited rainfall, abundant sunshine, and sufficient thermal resources. Temporal variations in temperature and precipitation during the soybean growing season are shown in Figure 1. The physicochemical properties of the soil (0–60 cm depth) in the experimental field are presented in Table 1.

Figure 1

Figure 1. Temperature and rainfall during soybean growth period.

Table 1

Table 1. Physicochemical properties of the soil (0–60 cm depth) in the experimental farmland.

2.2 Experimental design

A split-plot design with two factors was used. The main plot factor was tillage method: conventional tillage (CT) and no-till (NT). The subplot factor consisted of four nitrogen application rates: 0 kg·ha^-¹ (N0), 105 kg·ha^-¹ (N1), 150 kg·ha^-¹ (N2), and 195 kg·ha^-¹ (N3). The eight treatments were replicated three times. Each plot measured 20 m² (4 m × 5 m). Soybeans (cv. Haojiang 35, growth period 92 days) were sown on 2 July 2023 and 4 July 2024 at a depth of 2–3 cm, with row spacing of 30 cm, plant spacing of 6 cm, and a density of 5.55×10⁵ plants·ha^-¹. Chemical fertilizers included urea (46% N), potassium dihydrogen phosphate (52% P₂O₅, 34% K₂O), and potassium sulfate (51% K₂O). Irrigation was applied nine times during the growing season, synchronized with fertilizer application. Detailed fertilization rates are provided in Table 2. Other field management practices followed local standards.

Table 2

Table 2. Fertilization application for soybeans throughout the growth period.

2.3 Measurements and calculations

2.3.1 Grain yield

At maturity, ten uniformly growing plants were selected from each plot for indoor threshing to determine yield components and grain yield.

2.3.2 Soil water storage

Soil water content was determined by the drying method. Post-harvest, soil samples were taken from 0–60 cm depth at 20 cm intervals to measure soil water storage (SWS).

2.3.3 Soil total nitrogen

Soil samples from the 0–60 cm layer were collected after harvest, air-dried, and sieved. Soil total nitrogen (STN) was determined using the semi-micro Kjeldahl method at 20 cm depth intervals.

2.3.4 Leaf area index

During the peak flowering period (R2), peak podding period (R4), and grain filling period (R6), five uniformly growing soybean plants were selected from each experimental plot. The leaf area of each plant was measured using a LI-3000A leaf area meter to calculate the leaf area index (LAI).

2.3.5 Leaf chlorophyll content

During the R2, R4, and R6 stages of soybean growth, five soybean plants with uniform growth were selected from each plot. The SPAD values of the soybean trifoliate leaves were measured using a portable SPAD-502 chlorophyll meter. The mean value of each leaf was obtained through three independent measurements, with a particular effort to avoid the veins present within the leaf structure.

2.3.6 Photosynthetic parameters

In the course of the R2, R4, and R6 phases of soybean development, a portable photosynthesis system (LI-6400, USA) was utilized to identify five soybean plants exhibiting uniform growth from each plot. The net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), and intercellular CO₂ concentration (Ci) of the inverted trifoliate leaf were measured between 10:00 and 13:00 on sunny, cloudless mornings.

2.4 Statistical analysis

Data were organized using Microsoft Excel 2021. Statistical analyses were performed using IBM SPSS Statistics 20.0. A two-way analysis of variance (ANOVA) appropriate for the split-plot design was applied to test the significance (P < 0.05). Prior to ANOVA, assumptions of normality (Shapiro-Wilk test) and homogeneity of variances (Levene’s test) were verified. Mean separation was conducted using Tukey’s Honestly Significant Difference (HSD) test. Data visualization was performed using Origin 2021.

3 Results

3.1 Grain yield

Analysis of variance indicated that the main effects of year (Y) (p < 0.001), tillage (T) (p < 0.001), nitrogen (N) (p < 0.001), and the interactions of Y×T (p = 0.032), T×N (p < 0.001), and Y×T×N (p < 0.001) significantly affected soybean yield. The interaction of Y×N was not significant (p = 0.262) (Table 3). Specifically, under N0 conditions, yield under CT was 7.7–36.5% higher than under NT (P < 0.05) (Figure 2). Nitrogen application markedly increased yield in both systems up to the N2 rate (150 kg ha^-¹). Compared to CTN0, CTN2 yield increased by 14.5–42.6%, while the response was even greater under NT, with NTN2 yield increasing by 75.7–83.4% relative to NTN0. However, increasing the rate to N3 (195 kg ha^-¹) did not improve yield further; both CTN3 and NTN3 yields were significantly lower than those of their respective N2 treatments. The two-year average yield for NTN3 was numerically 8.9% higher than CTN3. These results suggest that while higher nitrogen rates can partially compensate for yield reduction under NT, the optimal N rate is system-dependent, and maintaining yield under NT requires precise N input management combined with long-term soil improvement.

Table 3

Table 3. Effects of tillage and nitrogen fertilizer application on soybean yield, 100-seed weight, and number of seeds per plant.

Figure 2

Figure 2. Effects of cultivation practices and nitrogen levels on soybean yield. Different letters denote significant differences (p < 0.05) within the same year.

3.2 Production composition factors

The hundred-seed weight and number of seeds per plant were significantly influenced by the main effects of year (Y) (p < 0.001), tillage (T) (p = 0.001 for hundred-seed weight; p < 0.001 for seeds per plant), nitrogen (N) (p < 0.001 for both), and the interactions of Y×N (p < 0.001 for both), T×N (p < 0.001 for both), and Y×T×N (p < 0.001 for hundred-seed weight; p = 0.005 for seeds per plant). The Y×T interaction was not significant for hundred-seed weight (p = 0.777) but was significant for the number of seeds per plant (p < 0.001) (Table 3). Overall, CT resulted in significantly higher hundred-seed weight and more seeds per plant than NT when averaged across nitrogen levels (Table 4). Nitrogen application up to the N2 rate consistently improved yield components in both tillage systems. The NTN2 treatment demonstrated substantial improvements, increasing the number of seeds per plant by 35.8–51.1% compared to NTN0 across both years (P < 0.05). Under CT conditions, the N2 rate also significantly increased yield components compared to CTN0. Conversely, increasing the nitrogen application to the N3 rate led to a consistent reduction in both hundred-seed weight and seeds per plant relative to the N2 rate in both tillage systems, indicating a negative effect of excessive nitrogen on yield formation. Notable interannual variability was observed in the response of hundred-seed weight to tillage practices. Nevertheless, the NTN2 treatment effectively enhanced yield components, with the number of seeds per plant reaching 37.09 and 64.50 in 2023 and 2024, respectively, representing significant improvements over the NTN0 treatment.

Table 4

Table 4. Effects of cultivation practices and nitrogen levels on the composition factors of soybean yield. Different letters denote significant differences (p < 0.05) within the same year.

3.3 Soil water storage

Soil water storage (SWS) was not significantly influenced by any main effects or interactions. The main effects of year (Y) (p = 0.119), tillage (T) (p = 0.854), nitrogen (N) (p = 0.996) and the interactions of Y×T (p = 0.932), Y×N (p = 0.703), T×N (p = 0.593), and Y×T×N (p = 0.223) were not significant (Table 5). Despite the lack of statistical significance, observed values showed considerable variation between years under different treatments (Figure 3). In 2023, under the N0 condition, SWS was numerically higher under CT than under NT across the 0–60 cm soil profile. By contrast, in 2024, NTN0 showed numerically higher SWS than CTN0 at the same depths. Nitrogen application at the N2 rate increased SWS relative to N0 in both tillage systems. Notably, the NTN2 treatment in 2024 maintained numerically higher SWS in the 20–60 cm layers compared to CTN2, with increases ranging from 12.5% to 21.7%. Additionally, the highest SWS values under nitrogen application were consistently observed in the N2 and N3 treatments. These results demonstrate that nitrogen application significantly influenced SWS, with the NTN2 regime exhibiting improved water retention in subsurface layers during the second year.

Table 5

Table 5. Effects of tillage and nitrogen fertilizer application on soil water storage and total soil nitrogen content.

Figure 3

Figure 3. Effects of cultivation practices and ntrogen levels on soil water storage.

3.4 Soil total nitrogen

Soil total nitrogen (STN) content was significantly influenced by the main effect of year (Y) (p = 0.001) and the interaction of Y×N (p < 0.001). The main effects of tillage (T) (p = 0.232), nitrogen (N) (p = 0.407) and the interactions of Y×T (p = 0.898), T×N (p = 0.561), and Y×T×N (p = 0.304) were not significant (Table 5). Considerable interannual variation was observed under the N0 condition. In 2023, STN under CTN0 was significantly higher than under NTN0 across all sampled soil layers (P < 0.05) (Figure 4). Conversely, in 2024, this trend was reversed in the upper soil layers (0–40 cm), where NTN0 surpassed CTN0 by 36.0–49.4%. The application of nitrogen at the N2 rate significantly increased STN under both tillage systems (P < 0.05). The NTN2 treatment consistently demonstrated substantial improvements in STN compared to NTN0, with increases of 51.1–135.1% observed across the two years. Notably, in 2024, NTN2 also resulted in numerically higher STN values than CTN2 in the subsurface layers (20–60 cm). These results indicate that while tillage practice alone did not significantly affect STN, its interaction with nitrogen application played a crucial role in determining soil nitrogen content, with the NTN2 combination showing particularly beneficial effects on soil nitrogen status.

Figure 4

Figure 4. Effects of cultivation practices and nitrogen levels on soil total nitrogen. Different letters denote significant differences (p < 0.05) within the same year.

3.5 Leaf area index

Leaf area index (LAI) was significantly influenced by the main effects of tillage (T) (p < 0.001) and nitrogen (N) (p = 0.007). The main effect of year (Y) (p = 0.637) and the interactions of Y×T (p = 0.395), Y×N (p = 0.523), T×N (p = 0.427), and Y×T×N (p = 0.464) were not significant (Table 6). CT resulted in significantly higher LAI than NT across growth stages and nitrogen levels (Figure 5). Nitrogen application markedly improved LAI in both tillage systems, with the N2 rate consistently producing the highest LAI values across all growth stages. The most substantial improvements were observed under the NT system with N2 application. NTN2 increased LAI by 32.3–76.8% at the R4 stage and by 36.4–36.8% at the R6 stage relative to NTN0. Similarly, under CT, CTN2 increased LAI by 18.3–101.8% at R2, 22.2–42.9% at R4, and 25.0–79.7% at R6 compared to CTN0. These results demonstrate that while CT generally maintained higher LAI than NT under equivalent nitrogen conditions, the application of nitrogen at the N2 rate effectively mitigated this difference, particularly during the critical R4 and R6 growth stages.

Table 6

Table 6. Effects of tillage and nitrogen fertilizer application on soybean leaf area index(LAI) and chlorophyll content (SPAD).

Figure 5

Figure 5. Effects of cultivation practices and nitrogen levels on soybean leaf area index (LAI). Different letters denote significant differences (p < 0.05) among treatments within the same year and growth stage.

3.6 SPAD

SPAD values were not significantly influenced by any of the main effects or their interactions (Table 6). This suggests that leaf chlorophyll content, as estimated by SPAD, was stable across the different management practices and experimental years. Despite the lack of significant effects, descriptive comparisons revealed trends. In 2023 under N0, CT exhibited numerically higher SPAD values than NT at all growth stages. Conversely, in 2024, NT showed numerically higher values than CT at the R2 and R6 stages (Figure 6). Nitrogen application markedly increased SPAD values in both tillage systems. The N2 treatment consistently produced the highest SPAD values across different growth stages, significantly outperforming the N0 treatment. Under NT, the NTN2 treatment increased SPAD values by 17.7–24.3% at the R4 stage and by 4.4–18.6% at the R6 stage compared to NTN0.

Figure 6

Figure 6. Effects of cultivation practices and nitrogen levels on soybean chlorophyll content (SPAD). Different letters within a column and factor indicate significant differences (p < 0.05).

3.7 Photosynthetic parameters

3.7.1 Net photosynthetic rate and transpiration rate

Pn was significantly influenced only by the main effect of year (Y) (p = 0.007). The main effects of tillage (T) (p = 0.879), nitrogen (N) (p = 0.555) and all interactions (Y×T, Y×N, T×N, Y×T×N; all p > 0.89) were not significant. Tr was significantly influenced by the main effects of year (Y) (p < 0.001) and nitrogen (N) (p < 0.001), and the interaction of Y×T (p = 0.029). The main effect of tillage (T) (p = 0.794) and the interactions of Y×N (p = 0.685), T×N (p = 0.354), and Y×T×N (p = 0.837) were not significant (Table 7). Descriptive comparisons of Pn and Tr values under N0 conditions revealed that differences between CT and NT varied with year and growth stage. In 2023, Pn at R2 was numerically higher under CT than NT, whereas at R4, NTN0 exceeded CTN0 (Table 8). Nitrogen application markedly improved Pn and Tr in both tillage systems. The N2 treatment consistently produced the highest values across growth stages. Under NT, the NTN2 treatment significantly increased Pn by 21.7–54.7% at R2, 8.8–9.0% at R4, and 21.8–23.2% at R6 compared to NTN0. Similarly, NTN2 increased Tr by 17.2–32.3% at R2, 14.8–64.3% at R4, and 18.0–45.6% at R6 over NTN0.

Table 7

Table 7. Effects of tillage and nitrogen fertilizer application on photosynthetic parameters of soybean.

Table 8

Table 8. Effects of cultivation practices and nitrogen levels on net photosynthetic rate (Pn) and transpiration rate (Tr) of soybeans.

3.7.2 Stomatal conductance and intercellular CO₂ concentration

Gs was significantly influenced by the main effects of tillage (T) (p = 0.046) and nitrogen (N) (p = 0.004). The main effect of year (Y) (p = 0.27) and all interactions (Y×T, Y×N, T×N, Y×T×N; all p > 0.60) were not significant. Ci was significantly influenced only by the main effect of year (Y) (p < 0.001). The main effects of tillage (T) (p = 0.972), nitrogen (N) (p = 0.905) and all interactions (Y×T, Y×N, T×N, Y×T×N; all p > 0.85) were not significant (Table 7). The T×N×Y interaction was also not significant. Descriptive comparisons revealed that the effects of tillage were inconsistent across years and growth stages. Under the N0 condition, Gs was numerically higher under NT than CT at the R4 stage in both years, but this trend was not observed at other stages. For Ci, N2 application generally resulted in numerically higher values compared to N0, particularly during the R6 stage. No consistent tillage effect was observed for Ci across the experimental period. (Table 9). Nitrogen application markedly increased Gs in both tillage systems, with the N2 rate producing the highest values. Under NT, the NTN2 treatment significantly increased Gs by 34.5–57.1% at R2, 9.5–19.4% at R4, and 32.3–62.1% at R6 compared to NTN0.

Table 9

Table 9. Effects of cultivation practices and nitrogen levels on stomatal conductance (Gs) and intercellular CO₂ concentration (Ci) in soybeans.

3.8 The relationship between yield and its influencing factors

Significant positive correlations (P < 0.05) were observed between grain yield (GY) and multiple physiological traits, including chlorophyll content (SPAD), net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), intercellular CO₂ concentration (Ci), leaf area index (LAI), along with the yield component hundred-seed weight (HSW) (Figure 7). Conversely, neither soil water storage (SWS) nor total soil nitrogen (STN) showed significant correlations with GY (P > 0.05).

Figure 7

Figure 7. Correlation analysis of grain yield (GY), hundred seed weight (HSW), number of seeds per plant (SNP), soil water storage capacity (SWS), soil total nitrogen (STN), leaf area index (LAI), chlorophyll content (SPAD), net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), and intercellular CO₂ concentration (Ci). Symbols * and ** indicate significance at p < 0.05 and p < 0.01, respectively.

4 Discussion

4.1 Effects of tillage methods and nitrogen on soybean yield and yield components

Integrated tillage and nitrogen (N) management is widely recognized as an effective strategy to overcome the limitations of single-factor agricultural practices, ultimately enhancing crop yield (Jiang et al., 2022; Zhang et al., 2023). This integrated approach is particularly critical during the transition from CT to NT, which often involves a period of yield decline (Li Z, et al., 2024). Under the N0 condition, the NT treatment significantly reduced seeds per plant and overall yield compared to CT, this overall yield decline was primarily driven by a consistent and significant reduction in the number of seeds per plant under NT (Imani et al., 2022). These reductions may be attributed to the initial immobilization of nitrogen under NT systems due to surface residue retention, which can limit early nutrient availability and impede root development during critical growth stages. Nitrogen optimization plays a pivotal role in maintaining soil fertility and maximizing yield potential (Fernández-Ortega et al., 2023). However, excessive N application—exemplified by the N3 rate in this study—can disrupt source-sink balance, leading to inefficient translocation of photoassimilates and impaired grain filling processes (Liu et al., 2018). Our results demonstrate that both CT and NT systems attained peak productivity at the N2 rate, beyond which yield losses occurred primarily due to reduced hundred-seed weight. This suggests that optimal N fertilization is essential for balancing vegetative and reproductive growth, regardless of tillage regime. Tillage practices profoundly influence the root zone environment by altering soil structure, residue distribution, and microbial community dynamics (Du et al., 2023). While CT facilitates nitrogen mineralization and root proliferation in the short term, promoting grain filling and seed weight (Ding et al., 2021), NT combined with optimal N (N2) achieved statistically comparable yields to CT in this study. This indicates that NT can effectively compensate for its early-growth limitations through improved water and nutrient retention over time. Moreover, NT under the N2 regime resulted in higher levels of soil moisture and nitrogen availability in the 2024 growing season, suggesting that long-term NT systems may foster a more resilient rhizosphere environment conducive to root-microbe interactions and sustained yield formation. The synergistic benefits of integrated tillage and N management highlight the importance of adapting agronomic practices to enhance system sustainability and productivity under evolving climatic conditions.

4.2 Cultivation methods and the regulatory effects of nitrogen on soil water and nitrogen environments

Tillage practices fundamentally alter soil physical structure and biogeochemical cycling, with contrasting mechanisms driving system performance. CT improves short-term aeration and water infiltration by mechanically loosening the soil profile; however, long-term use disrupts aggregate stability, accelerates organic matter mineralization, and can lead to subsurface compaction (Hu et al., 2018). In contrast, NT minimizes mechanical disturbance, preserves biopore-derived porosity, and enhances surface residue retention. These features collectively mitigate erosion and reduce nitrogen loss by slowing organic matter decomposition and mineralization rates (Brevilieri et al., 2024; Song et al., 2024; Zhang et al., 2025). Our results revealed notable interannual variability in SWS and STN under NT without nitrogen application (NTN0). The higher SWS under CTN0 in 2023 can be attributed to improved initial infiltration in the freshly tilled and loosened soil. The reversal in 2024, however, suggests a progressive improvement in NT’s soil structural properties and hydrological functioning. Over time, continued residue accumulation, fungal hyphae development, and earthworm activity enhance pore connectivity and water-stable aggregation, thereby increasing water retention capacity—a process consistent with models of ecosystem development in reduced-disturbance systems (Wen et al., 2024). Furthermore, the positive correlation between STN and SWS in upper soil layers (0–40 cm) under NT underscores the role of coupled hydro-nutrient retention in surface horizons, likely mediated by organic material accumulation and reduced evaporative loss. However, the significant reduction in STN in deeper soil layers (40–60 cm) under NTN0 compared to CT highlights a potential limitation of NT in regulating nutrient leaching. This may be attributed to reduced root exploration in the subsoil under NT during early transition periods, along with the development of preferential flow paths through biopores and cracks, which can facilitate the downward movement of soluble nitrogen before plants establish extensive root systems. Application of nitrogen at the N2 rate ameliorated these constraints through multiple mechanisms: NTN2 not only retained more water in the 20–60 cm depth than CTN2 but also maintained higher STN, likely due to improved plant growth, enhanced root-derived carbon inputs, and stimulated microbial activity that promotes nutrient immobilization and cycling (Fashi et al., 2019; Wang et al., 2021). The deeper rooting system encouraged under stabilized NT environments also facilitates nutrient uptake from subsurface layers, reducing leaching losses. Conversely, the N3-induced reductions in STN across all depths reflect exacerbated leaching risks, particularly below 40 cm. This is consistent with reports of increased nitrate mobility under excessive N inputs, which overwhelm plant uptake and microbial immobilization capacity, leading to displacement of nitrogen beyond the root zone (Carvalho et al., 2024; Fang et al., 2006). The deeper leaching under N3 also implies that NT systems, despite their surface advantages, are not immune to nitrogen loss through leaching under imbalanced fertilization, highlighting the necessity of coupling tillage practices with precise nitrogen management to achieve both agronomic and environmental objectives.

4.3 Cultivation methods and nitrogen improve photosynthetic characteristics of soybeans

Photosynthetic performance is intimately linked to soil management practices through their effects on water availability, nitrogen supply, and root system functioning. The observed superiority in LAI and SPAD values under CTN0 compared to NTN0 can be attributed to improved early-stage root exploration in the mechanically loosened soil of CT systems, facilitating greater access to soil moisture and nutrients—particularly nitrogen—which in turn promotes canopy development and chlorophyll accumulation (Farhangi-Abriz et al., 2021; Hafeez et al., 2019). By contrast, the compacted and less-aerated soil typical of initial NT systems can physically constrain root growth and limit early nutrient uptake, resulting in delayed canopy establishment. However, NT systems exhibited a pronounced and compensatory response to nitrogen addition. The significant increases in LAI, SPAD, Pn, and Gs under NT with N2 indicate that nitrogen application effectively mitigated these early physiological constraints. The mechanism likely involves improved leaf nitrogen status, facilitating enhanced chlorophyll biosynthesis and greater photosynthetic enzyme activity, which collectively elevate light capture and carbon assimilation capacity (Nkebiwe et al., 2016; Qiang et al., 2025; Savala et al., 2021). The depression in Pn coinciding with elevated Ci values across treatments in 2024, particularly under NT, suggests the presence of non-stomatal limitations to photosynthesis. This may reflect metabolic impediments such as reduced Rubisco activity, diminished electron transport capacity, or feedback inhibition due to carbohydrate accumulation—all of which can occur under suboptimal source-sink balance or abiotic stress (Buczek et al., 2022). Notably, the superior photosynthetic performance in NT during 2024 indicates that the system underwent functional adaptation over time. We propose that this enhancement arises from improved microbial-mediated nitrogen mineralization and stabilization (Zhang et al., 2020), combined with the development of a deeper and more branched root architecture that better accesses subsurface water and nutrients (Jeelani, 2017). Furthermore, the accumulation of soil organic matter and stabilization of soil aggregates under NT may enhance moisture retention and microclimate conditions, supporting more sustained photosynthetic activity during critical growth stages. These findings illustrate that while CT can create initially favorable physical conditions for crop growth, NT—when paired with optimized nitrogen input—fosters a more resilient and efficient photosynthetic apparatus. The results underscore the importance of biological adaptation and nutrient–water synergism in no-till systems, highlighting their capacity to not only compensate for early limitations but also to achieve sustained photosynthetic productivity under variable environmental conditions.

5 Conclusion

The NTN2 system significantly enhanced soil water storage (SWS) and soil total nitrogen (STN) compared to NTN0 (P < 0.05), improved leaf area index (LAI) during the R4–R6 growth stages, and increased SPAD values, net photosynthetic rate (Pn), and stomatal conductance (Gs), ultimately leading to a 75.7–83.4% increase in grain yield (GY) relative to NTN0 (P < 0.05). Crucially, the application of 150 kg N ha^-¹ alleviated tillage-imposed limitations, allowing no-till (NT) to achieve yields comparable to conventional tillage with nitrogen application (CTN2) (P > 0.05). These results demonstrate that integrating no-till with moderate nitrogen fertilization effectively optimizes soybean productivity and resource-use efficiency by improving water and nitrogen availability in the arid northwestern region of China. The findings underscore the potential of tailored tillage–nutrient synergy as a sustainable strategy to enhance crop resilience in water-limited environments. Future studies should focus on long-term field validations and extend the approach to other legume crops or comparable arid and semiarid agroecosystems.

Data availability statement

The original contributions presented in the study are included in the article/supplementary material. Further inquiries can be directed to the corresponding author.

Author contributions

KZ: Conceptualization, Data curation, Formal analysis, Investigation, Project administration, Visualization, Writing – original draft, Writing – review & editing. HH: Conceptualization, Data curation, Investigation, Methodology, Project administration, Writing – review & editing. JJ: Conceptualization, Investigation, Methodology, Writing – review & editing. JL: Conceptualization, Funding acquisition, Methodology, Project administration, Resources, Supervision, Validation, Data curation, Writing – review & editing.

Funding

The author(s) declare financial support was received for the research, and/or publication of this article. This study was supported by the Program of the Science and Technology Plan Project of Xinjiang Production and Construction Corps (No. 2025DA028).

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Generative AI statement

The author(s) declare that no Generative AI was used in the creation of this manuscript.

Any alternative text (alt text) provided alongside figures in this article has been generated by Frontiers with the support of artificial intelligence and reasonable efforts have been made to ensure accuracy, including review by the authors wherever possible. If you identify any issues, please contact us.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

References

Bassi D., Menossi M., and Mattiello L. (2018). Nitrogen supply influences photosynthesis establishment along the sugarcane leaf. Sci. Rep. 8, 13. doi: 10.1038/s41598-018-20653-1

PubMed Abstract | Crossref Full Text | Google Scholar

Brevilieri R. C., Dieckow J., Barth G., Veloso M. G., Pergher M., Pauletti V., et al. (2024). No-tillage and fertilization effectively improved soil carbon and nitrogen in a subtropical ferralsol. Soil Tillage Res. 241, 106095. doi: 10.1016/j.still.2024.106095

Crossref Full Text | Google Scholar

Buczek J., Bobrecka-Jamro D., and Jańczak-Pieniążek M. (2022). Photosynthesis, yield and quality of soybean (glycine max (l.) Merr.) Under different soil-tillage systems. Sustainability 14, 4903. doi: 10.3390/su14094903

Crossref Full Text | Google Scholar

Carvalho A. M. D., Ramos M. L. G., Da Silva V. G., de Sousa T. R., Malaquias J. V., Ribeiro F. P., et al. (2024). Cover crops affect soil mineral nitrogen and n fertilizer use efficiency of maize no-tillage system in the Brazilian cerrado. Land 13, 693. doi: 10.3390/land13050693

Crossref Full Text | Google Scholar

Dai Z., Hu J., Fan J., Fu W., Wang H., and Hao M. (2021). No-tillage with mulching improves maize yield in dryland farming through regulating soil temperature, water and nitrate-n. Agriculture Ecosyst. Environ. 309, 107288. doi: 10.1016/j.agee.2020.107288

Crossref Full Text | Google Scholar

De Notaris C., Rasmussen J., Sørensen P., Melander B., and Olesen J. E. (2019). Manipulating cover crop growth by adjusting sowing time and cereal inter-row spacing to enhance residual nitrogen effects. Field Crops Res. 234, 15–25. doi: 10.1016/j.fcr.2019.02.008

Crossref Full Text | Google Scholar

Ding J., Li F., Xu D., Wu P., Zhu M., Li C., et al. (2021). Tillage and nitrogen managements increased wheat yield through promoting vigor growth and production of tillers. Agron. J. 113, 1640–1652. doi: 10.1002/agj2.20562

Crossref Full Text | Google Scholar

Du C. L., Li L. L., Effah Z., Xu J., Xie J. H., Luo Z. Z., et al. (2023). Different tillage and stubble management practices affect root growth and wheat production in a semi-arid area. Plant Soil. 502, 211–225. doi: 10.1007/s11104-023-06076-6

Crossref Full Text | Google Scholar

Fang Q., Yu Q., Wang E., Chen Y., Zhang G., Wang J., et al. (2006). Soil nitrate accumulation, leaching and crop nitrogen use as influenced by fertilization and irrigation in an intensive wheat–maize double cropping system in the north China plain. Plant Soil 284, 335–350. doi: 10.1007/s11104-006-0055-7

Crossref Full Text | Google Scholar

Farhangi-Abriz S., Ghassemi-Golezani K., and Torabian S. (2021). A short-term study of soil microbial activities and soybean productivity under tillage systems with low soil organic matter. Appl. Soil Ecol. 168, 9. doi: 10.1016/j.apsoil.2021.104122

Crossref Full Text | Google Scholar

Fashi F. H., Gorji M., and Sharifi F. (2019). Temporal variability of soil water content and penetration resistance under different soil management practices. J. Soil Water Conserv. 74, 188–198. doi: 10.2489/jswc.74.2.188

Crossref Full Text | Google Scholar

Fernández-Ortega J., álvaro-Fuentes J., Talukder R., Lampurlanés J., and Cantero-Martínez C. (2023). The use of double-cropping in combination with no-tillage and optimized nitrogen fertilization improve crop yield and water use efficiency under irrigated conditions. Field Crops Res. 301, 109017. doi: 10.1016/j.fcr.2023.109017

Crossref Full Text | Google Scholar

Foloni J. S. S., Silva S. R., Abati J., de Oliveira Junior A., de Castro C., de Oliveira F. A., et al. (2023). Yield of soybean-wheat succession in no-tillage system and soil chemical properties affected by liming, aluminum tolerance of wheat cultivars, and nitrogen fertilization. Soil Tillage Res. 226, 105576. doi: 10.1016/j.still.2022.105576

Crossref Full Text | Google Scholar

Franco-Luesma S., Cavero J., and álvaro-Fuentes J. (2025). Relevance of the irrigation and soil management system to optimize maize crop production under semiarid mediterranean conditions. Agric. Water Manag 307, 109272. doi: 10.1016/j.agwat.2024.109272

Crossref Full Text | Google Scholar

Guo Y., Yin W., Chai Q., Yu A., Zhao C., Fan Z., et al. (2021). No tillage and previous residual plastic mulching with reduced water and nitrogen supply reduces soil carbon emission and enhances productivity of following wheat in arid irrigation areas. Field Crops Res. 262, 108028. doi: 10.1016/j.fcr.2020.108028

Crossref Full Text | Google Scholar

Hafeez A., Ali S., Ma X., Tung S. A., Shah A. N., Ahmad S., et al. (2019). Photosynthetic characteristics of boll subtending leaves are substantially influenced by applied k to n ratio under the new planting model for cotton in the yangtze river valley. Field Crops Research (2019) 237, 43–52. doi: 10.1016/j.fcr.2019.04.015

Crossref Full Text | Google Scholar

Hati K. M., Jha P., Dalal R. C., Jayaraman S., Dang Y. P., Kopittke P. M., et al. (2021). 50 years of continuous no-tillage, stubble retention and nitrogen fertilization enhanced macro-aggregate formation and stabilisation in a vertisol. Soil Tillage Res. 214, 105163. doi: 10.1016/j.still.2021.105163

Crossref Full Text | Google Scholar

Hu T., Sørensen P., and Olesen J. E. (2018). Soil carbon varies between different organic and conventional management schemes in arable agriculture. Eur. J. Agron. 94, 79–88. doi: 10.1016/j.eja.2018.01.010

Crossref Full Text | Google Scholar

Hu Z., Zhao Q., Zhang X., Ning X., Liang H., and Cao W. (2023). Winter green manure decreases subsoil nitrate accumulation and increases n use efficiencies of maize production in north China plain. Plants 12, 311. doi: 10.3390/plants12020311

PubMed Abstract | Crossref Full Text | Google Scholar

Imani R., Samdeliri M., and Mirkalaei A. M. (2022). The effect of different tillage methods and nitrogen chemical fertilizer on quantitative and qualitative characteristics of corn. Int. J. Anal. Chem. 2022, 1–11. doi: 10.1155/2022/7550079

PubMed Abstract | Crossref Full Text | Google Scholar

Jeelani J. (2017). Effect of varying drip irrigation levels and different methods of NPK fertilizer application on soil water dynamics, water use efficiency and yield of broccoli (brassica oleracea l. Var. Italica) in wet temperate zone of himachal pradesh. Int. J. Pure Appl. Bioscience 5, 210–220. doi: 10.18782/2320-7051.2496

Crossref Full Text | Google Scholar

Jiang Q., Madramootoo C. A., and Qi Z. (2022). Soil carbon and nitrous oxide dynamics in corn (zea mays l.) Production under different nitrogen, tillage and residue management practices. Field Crops Res. 277, 108421. doi: 10.1016/j.fcr.2021.108421

Crossref Full Text | Google Scholar

Kang J., Chu Y., Ma G., Zhang Y., Zhang X., Wang M., et al. (2023). Physiological mechanisms underlying reduced photosynthesis in wheat leaves grown in the field under conditions of nitrogen and water deficiency. Crop J. 11, 638–650. doi: 10.1016/j.cj.2022.06.010

Crossref Full Text | Google Scholar

Lamptey S., Li L., Xie J., Zhang R., Yeboah S., and Antille D. L. (2017). Photosynthetic response of maize to nitrogen fertilization in the semiarid western loess plateau of China. Crop Sci. 57, 2739–2752. doi: 10.2135/cropsci2016.12.1021

Crossref Full Text | Google Scholar

Li Z., Sun X., Pan J., Wang T., Li Y., Li X., et al. (2024). Combining no-tillage with hairy vetch return improves production and nitrogen utilization in silage maize. Plants 13, 2084. doi: 10.3390/plants13152084

PubMed Abstract | Crossref Full Text | Google Scholar

Li X., Wang R., Lou F., Ji P., Wang J., Dong W., et al. (2024). Subsoiling combine with layered nitrogen application optimizes root distribution and improve grain yield and n efficiency of summer maize. Agronomy-Basel 14, 1228. doi: 10.3390/agronomy14061228

Crossref Full Text | Google Scholar

Li Z., Zhang Q., Li F., Li Z., Qiao Y., Du K., et al. (2023). Soil CO2 emission reduction with no-tillage and medium nitrogen fertilizer applications in semi-humid maize cropland in north China plain. Eur. J. Agron. 147, 126838. doi: 10.1016/j.eja.2023.126838

Crossref Full Text | Google Scholar

Liu Z., Gao J., Gao F., Liu P., Zhao B., and Zhang J. (2018). Photosynthetic characteristics and chloroplast ultrastructure of summer maize response to different nitrogen supplies. Front. Plant Sci. 9. doi: 10.3389/fpls.2018.00576

PubMed Abstract | Crossref Full Text | Google Scholar

Majrashi M. A., Obour A. K., Moorberg C. J., Lollato R. P., Holman J. D., Du J., et al. (2023). Tillage and nitrogen rate effects on winter wheat yield in a wheat–sorghum rotation. Can. J. Soil Sci. 103, 671–683. doi: 10.1139/cjss-2023-0028

Crossref Full Text | Google Scholar

Nkebiwe P. M., Weinmann M., Bar-Tal A., and Mueller T. (2016). Fertilizer placement to improve crop nutrient acquisition and yield: a review and meta-analysis. Field Crops Res. 196, 389–401. doi: 10.1016/j.fcr.2016.07.018

Crossref Full Text | Google Scholar

Piao L., Li M., Xiao J., Gu W., Zhan M., Cao C., et al. (2019). Effects of soil tillage and canopy optimization on grain yield, root growth, and water use efficiency of rainfed maize in northeast China. Agronomy-Basel 9, 336. doi: 10.3390/agronomy9060336

Crossref Full Text | Google Scholar

Qiang B., Chen S., Fan Z., Cao L., Li X., Fu C., et al. (2025). Effects of nitrogen application levels on soybean photosynthetic performance and yield: insights from canopy nitrogen allocation studies. Field Crops Res. 326, 14. doi: 10.1016/j.fcr.2025.109871

Crossref Full Text | Google Scholar

Sainju U. M., Liptzin D., Dangi S., and Ghimire R. (2021). Soil health indicators and crop yield in response to long-term cropping sequence and nitrogen fertilization. Appl. Soil Ecol. 168, 104182. doi: 10.1016/j.apsoil.2021.104182

Crossref Full Text | Google Scholar

Savala C. E. N., Wiredu A. N., Okoth J. O., and Kyei-Boahen S. (2021). Inoculant, nitrogen and phosphorus improves photosynthesis and water-use efficiency in soybean production. J. Agric. Sci. 159, 349–362. doi: 10.1017/S0021859621000617

Crossref Full Text | Google Scholar

Seepaul R., Kumar S., Sidhu S., Small I. M., George S., Douglas M., et al. (2023). Effect of tillage and nitrogen fertility on growth, yield, and seed chemical composition of rainfedbrassica carinata. Agron. J. 115, 1384–1398. doi: 10.1002/agj2.21315

Crossref Full Text | Google Scholar

Song F., Liu M., Zhang Z., Qi Z., Li T., Du S., et al. (2024). No-tillage with straw mulching increased maize yield and nitrogen fertilizer recovery rate in northeast China. Agric. Water Manage. 292, 108687. doi: 10.1016/j.agwat.2024.108687

Crossref Full Text | Google Scholar

Suarez-Tapia A., Thomsen I. K., Rasmussen J., and Christensen B. T. (2018). Residual n effect of long-term applications of cattle slurry using winter wheat as test crop. Field Crops Res. 221, 257–264. doi: 10.1016/j.fcr.2017.10.013

Crossref Full Text | Google Scholar

Vizioli B., Cavalieri-Polizeli K. M. V., Tormena C. A., and Barth G. (2021). Effects of long-term tillage systems on soil physical quality and crop yield in a Brazilian ferralsol. Soil Tillage Res. 209, 104935. doi: 10.1016/j.still.2021.104935

Crossref Full Text | Google Scholar

Wang J., Liu W. Z., Dang T. H., and Sainju U. M. (2013). Nitrogen fertilization effect on soil water and wheat yield in the chinese loess plateau. Agron. J. 105, 143–149. doi: 10.2134/agronj2012.0067

Crossref Full Text | Google Scholar

Wang Y., Lyu H., Yu A., Wang F., Li Y., Wang P., et al. (2024). No-tillage mulch with green manure retention improves maize yield by increasing the net photosynthetic rate. Eur. J. Agron. 159, 127275. doi: 10.1016/j.eja.2024.127275

Crossref Full Text | Google Scholar

Wang Y. K., Zhang Z. B., Jiang F. H., Guo Z. C., and Peng X. H. (2021). Evaluating soil physical quality indicators of a vertisol as affected by different tillage practices under wheat-maize system in the north China plain. Soil Tillage Res. 209, 104970. doi: 10.1016/j.still.2021.104970

Crossref Full Text | Google Scholar

Wang X., Zhu Y., Yan Y., Hou J., Wang H., Luo N., et al. (2023). Irrigation mitigates the heat impacts on photosynthesis during grain filling in maize. J. Integr. Agric. 22, 2370–2383. doi: 10.1016/j.jia.2023.02.012

Crossref Full Text | Google Scholar

Wen L., Peng Y., Lin Y., Zhou Y., Cai G., Li B., et al. (2024). Conservation tillage increases nutrient accumulation by promoting soil enzyme activity: a meta-analysis. Plant Soil. 508, 531–546. doi: 10.1007/s11104-024-06817-1

Crossref Full Text | Google Scholar

Yue K., Li L., Xie J., Wang L., Liu Y., and Anwar S. (2022). Tillage and nitrogen supply affects maize yield by regulating photosynthetic capacity, hormonal changes and grain filling in the loess plateau. Soil Tillage Res. 218, 105317. doi: 10.1016/j.still.2022.105317

Crossref Full Text | Google Scholar

Zhang Y., Bhattacharyya R., Finn D., Birt H. W. G., Dennis P. G., Dalal R. C., et al. (2023). Soil carbon, nitrogen, and biotic properties after long-term no-till and nitrogen fertilization in a subtropical vertisol. Soil Tillage Res. 227, 105614. doi: 10.1016/j.still.2022.105614

Crossref Full Text | Google Scholar

Zhang Y., Dalal R. C., Bhattacharyya R., Meyer G., Wang P., Menzies N. W., et al. (2021). Effect of long-term no-tillage and nitrogen fertilization on phosphorus distribution in bulk soil and aggregates of a vertisol. Soil Tillage Res. 205, 104760. doi: 10.1016/j.still.2020.104760

Crossref Full Text | Google Scholar

Zhang K., Duan M., Xu Q., Wang Z., Liu B., and Wang L. (2020). Soil microbial functional diversity and root growth responses to soil amendments contribute to CO2 emission in rainfed cropland. Catena 195, 104747. doi: 10.1016/j.catena.2020.104747

Crossref Full Text | Google Scholar

Zhang S., Peng Y., Zhang F., Li Z., and Weng W. (2025). Impact of no-tillage and reduced nitrogen input on corn yield and nitrogen efficiency in the corn belt of northeast China. Field Crops Res. 322, 109742. doi: 10.1016/j.fcr.2025.109742

Crossref Full Text | Google Scholar

Zhang W., Yang S., Jin Y., Liu P., and Lou S. (2020). The effects of straw mulching combined with nitrogen applications on the root distributions and nitrogen utilization efficiency of summer maize. Sci. Rep. 10, 21082. doi: 10.1038/s41598-020-78112-9

PubMed Abstract | Crossref Full Text | Google Scholar

Zhou Z. and Oosterhuis D. M. (2012). Physiological mechanism of nitrogen mediating cotton (&lt;i<gossypium hirsutum&lt;/I< L.) Seedlings growth under water-stress conditions. Am. J. Plant Sci. 03, 721–730. doi: 10.4236/ajps.2012.36087

Crossref Full Text | Google Scholar