Integrated Drip Irrigation Regulates Soil Water–Salt Movement to Improve Water Use Efficiency and Maize Yield in Saline–Alkali Soil

Abstract

Soil salinization is a critical issue impacting agriculture, particularly in arid and semi-arid regions. The objective of this study was to evaluate the effects of different drip irrigation and fertilization treatments on soil water and salt dynamics, maize water use efficiency, and crop yield in the saline–alkali soils of northern Ningxia, China. Over three years, four irrigation treatments were tested: CK (flood irrigation, 810 mm), W1 (low-volume drip irrigation, 360 mm), W2 (medium-volume drip irrigation, 450 mm), and W3 (high-volume drip irrigation, 540 mm). The results demonstrate that treatments W2 and W3 significantly increased soil moisture content at depths of 0–20 cm and 60–100 cm compared to CK, facilitating uniform salt leaching in the 0–40 cm soil layer. However, in the 40–100 cm layer, decreased porosity and upward moisture movement hindered salt migration, resulting in subsurface salt accumulation. Furthermore, drip irrigation combined with fertilization significantly reduced phosphorus fixation and nitrogen leaching, enhancing nutrient availability. This led to a reduction in underground leakage and surface evaporation by up to 39.63%, while water use efficiency improved by 18.97% to 55.13%. By the third year, grain yields under drip irrigation treatments increased significantly compared to CK, with W3 showing the highest gains (up to 21.90%). This study highlights the potential of integrating drip irrigation and fertilization as an effective strategy for managing saline–alkali soils, improving water use, and increasing crop productivity, providing valuable insights for sustainable agricultural practices.

1. Introduction

Soil salinization is a global environmental issue that has led to vast tracts of land becoming barren, severely impacting food security and the livelihoods of farmers. Globally, regions such as the Central Asian steppes, the Middle East, and parts of South America have also faced the devastating effects of soil salinization, exacerbating food insecurity and economic instability [1]. Currently, approximately 9.5 × 10⁹ ha of land worldwide is affected by varying degrees of salinization, accounting for about 10% of the global arable land area, with an annual increase of 1 × 10⁶ to 2.5 × 10⁶ ha [2,3]. These barren lands particularly threaten agricultural productivity in semi-arid and arid regions where food production heavily relies on irrigation and soil health maintenance. In China, approximately 50 million hectares of saline–alkali soil is predominantly distributed across the northeastern, northern, northwestern, and coastal regions, presenting substantial challenges to sustainable agricultural development. Among these regions, the Hetao Plain stands out due to its long history of agriculture and fertile soils, serving as a vital agricultural hub and a significant producer of staple crops in the country [4]. Secondary salinization, a process largely driven by human-induced factors such as inefficient irrigation practices, has exacerbated soil degradation in many agricultural regions. In the Hetao Plain, this issue is particularly pronounced, with severe soil salinization resulting from a combination of high evaporation rates, over-irrigation, and poor drainage systems. These factors not only compromise soil health but also threaten the region’s ability to continue functioning as a major producer of staple crops. Similarly, in countries like India and Pakistan, salinization has significantly reduced the productivity of historically fertile regions [5,6]. This trend has also been observed in the Nile Delta, where soil degradation has threatened food production in one of the world’s most densely cultivated areas [7]. Northern Ningxia, with an average annual precipitation of only 200 mm, experiences extreme aridity due to evaporation rates as high as 2000 mm. This imbalance in water availability and demand creates a challenging environment for agricultural production, particularly in saline–alkali soils that require precise water management to prevent salinization [8]. Additionally, the region’s limited water resources heighten the need for efficient irrigation methods to sustain crop yields in this harsh climate. Unlike other regions, the secondary salinization process in northern Ningxia’s soils is driven by a combination of natural factors, such as high evaporation rates, and human activities, including long-term reliance on inefficient irrigation practices. Being adjacent to the Yellow River, the local area benefits from convenient irrigation. Prolonged and continuous surface irrigation with Yellow River water raises the groundwater level, causing salt accumulation on the soil surface through evapotranspiration, leading to severe secondary soil salinization [9]. Extensive moderately to severely saline–alkali soils in Ningxia have been abandoned, significantly reducing arable land resources, lowering crop yields, and hindering high-quality development and ecological restoration. The loss of productivity in these saline–alkali soils has constrained sustainable agriculture in the Yellow River Basin, where soil degradation further complicates efforts to restore land for productive use [10]. Soil salinization results from the combined effects of water and salt and is closely related to irrigation methods, cultivation practices, climatic conditions, soil types, and other factors [11].

The essence of soil improvement measures for saline–alkali soil lies in regulating soil water–salt movement, accelerating the downward leaching of soil salts, and impeding upward salt migration to the soil surface due to evapotranspiration [12]. Traditional hydraulic engineering improvement measures often involve using flood irrigation to flush out salts, a practice that not only wastes valuable water resources but also increases environmental risks such as groundwater contamination, nutrient runoff, and ecosystem degradation [13]. The limited availability of this resource in northern Ningxia makes these traditional methods economically unsustainable, driving the need for more efficient irrigation strategies that conserve water while preventing soil degradation. Farmers in Ningxia have long relied on surface irrigation from the Yellow River, which has contributed to low water use efficiency, secondary soil salinization, and declining productivity. Given the region’s high evaporative demand and limited freshwater resources, surface irrigation practices have also exacerbated the region’s vulnerability to droughts, further limiting agricultural production. The inefficient use of water not only raises farming costs but also increases the environmental footprint of irrigation, pushing for a shift towards more sustainable techniques. Therefore, it is urgent to research field irrigation technology to support agricultural development in Ningxia. Drip irrigation with integrated water and fertilizer application can achieve salt flushing via high-frequency, precise irrigation, allowing water and nutrients to infiltrate the soil uniformly. This process reduces subsurface soil solution percolation and surface runoff while locally leaching salts, creating a suitable microenvironment near the drip emitter with ample water and a low salt content. In Israel, drip irrigation has been successfully implemented to reclaim saline soils, significantly enhancing water use efficiency and crop productivity in arid regions [14]. Similarly, Mexico’s adoption of drip irrigation in its arid northern regions has led to marked improvements in soil health and agricultural yields [15]. This technology enhances water use efficiency and crop yields [16] and has become one of the most effective methods for developing low-productivity farmland, widely used on saline–alkali soil at home and abroad [12].

Previous studies have predominantly concentrated on the effects of single-drip irrigation systems with integrated water and fertilizer applications on soil amelioration and crop yield improvement in saline–alkali soils [17,18,19]. While effective, these methods often overlook the intricate dynamics of soil water and salt distribution under varying irrigation patterns, and their long-term impacts on crop physiology, nutrient uptake, and soil sustainability. Traditional surface irrigation methods, such as flood irrigation, have been widely used due to their simplicity and cost-effectiveness, particularly in regions with access to ample water resources. However, these methods suffer from inefficiencies, including excessive water use, poor distribution uniformity, and a tendency to exacerbate secondary salinization through the accumulation of salts near the soil surface. In contrast, drip irrigation, especially when integrated with fertigation, offers precise water and nutrient delivery directly to the root zone, reducing water wastage and limiting salt buildup in the topsoil. However, one drawback of drip irrigation is the high initial installation cost and the need for maintenance to prevent emitter clogging. Recent studies from Australia and the Middle East [20,21] have shown that adjustments in irrigation regimes—especially under fluctuating climatic conditions—can profoundly impact soil salinity levels and crop productivity. Building on these findings, the present study takes a more comprehensive approach by examining the long-term effects of various irrigation strategies on soil water–salt dynamics, emphasizing their cumulative impact on crop development, soil health, and overall productivity.

Unlike previous research, which has primarily focused on short-term effects, this study provides a comprehensive evaluation of the long-term interactions between soil water, salt, and crop growth under different irrigation practices. By addressing the complex relationships between water–salt movement, nutrient bioavailability, and crop performance over three consecutive years, this research fills a critical knowledge gap. The findings will contribute to the development of more efficient irrigation techniques that can mitigate soil salinity, enhance water use efficiency, and promote sustainable agricultural production in saline–alkali soils. Ultimately, this study aims to provide a robust framework for optimizing irrigation practices in degraded lands, particularly in the Hetao Irrigation Area.

In this study, a three-year field experiment was conducted on saline–alkali soil in northern Ningxia to investigate the effects of varying irrigation quotas on soil water dynamics, salt content, and water utilization in maize (Zea mays L.). The research focuses on the integrated application of water and fertilizers and their subsequent impact on soil salinity and crop performance. Maize was selected for its significance as a staple and forage crop in arid and semi-arid regions, its inherent tolerance to saline conditions, and its potential to produce high yields when subjected to optimized irrigation regimes. By assessing the long-term effects of different irrigation methods on soil water–salt interactions and maize growth over three consecutive years, this study seeks to offer theoretical insights and technical guidance for the sustainable development and efficient utilization of drip-irrigated saline–alkali soils. The findings are expected to enhance our understanding of water and salt movement under drip irrigation, providing a solid foundation for future practices in water conservation, salt management, and yield optimization in saline–alkali agricultural landscapes, particularly in the Hetao Irrigation Area.

2. Materials and Methods

2.1. Experimental Site

The experimental site is located in Jiaoji Village, Qukou Township, Pingluo County, Shizuishan city, Ningxia Hui Autonomous Region (36°14′ N, 106°01′ E, altitude 1105 m). The trial area falls under a temperate continental semi-arid climate, with an average annual temperature of 8.7 °C; an effective accumulated temperature of 3100–3300 °C; a diurnal temperature variation of 10–15 °C; average annual sunshine duration of 2800–3000 h; a sunshine rate of 68%; average annual precipitation of 190–210 mm; and annual evaporation of 2000 mm. The frost-free period lasts 160–170 days. Groundwater levels in the area rise during the irrigation season and typically fluctuate between 1.9 m and 3.1 m. During the non-irrigation season, groundwater levels fall and depth to groundwater fluctuates between 5 m and 6 m. Groundwater salinity usually fluctuates between 0.5 and 2 g L⁻¹, depending on irrigation intensity, precipitation, and changes in groundwater levels. The soil type is saline–alkali alluvial soil, with a medium texture. The baseline values of soil pH and total salt and fractionated salt contents are listed in

Table 1. Saline–alkali soil background values.

Soil Layer (cm)	pH Value	Total Salt (g·kg−1)	Ca2+ (g·kg−1)	Mg2+ (g·kg−1)	K+ (g·kg−1)	Na+ (g·kg−1)	CO32− (mg·kg−1)	HCO3− (g·kg−1)	SO42− (g·kg−1)	Cl− (g·kg−1)
0–20	8.86	9.63	0.60	1.28	0.06	0.72	1.79	0.09	0.13	0.07
20–40	8.84	8.75	0.55	1.13	0.06	0.58	1.61	0.09	0.08	0.06
40–60	8.97	8.11	0.37	1.02	0.05	0.67	1.73	0.09	0.12	0.05
60–80	9.04	7.16	0.35	0.96	0.03	0.69	1.72	0.08	0.11	0.05
80–100	8.98	6.67	0.32	0.94	0.03	0.77	1.52	0.08	0.08	0.06

.

2.2. Experimental Design

The trial, initiated in 2021, was conducted over three consecutive years. Seeds were sown on April 30 and harvested between September 10 and 15, with each annual trial lasting 130 days, using the maize variety Daikyojiu 26. A wide–narrow row planting pattern (Figure 1B) was implemented, with wide rows spaced at 60 cm, narrow rows at 40 cm, and plants at 22 cm intervals [22]. The main drip irrigation system consisted of solenoid valves, pressure gauges, flow meters, screen filters, and fertilizer tanks. Each treatment plot was equipped with an independent drip irrigation control system to regulate water application within the plot. Drip tapes were laid within the narrow rows with 20 cm between drip emitters, each emitting 1.27 L h⁻¹ [23]. Utilizing the irrigation practices of local farmers, the study applied a model and techniques for water conservation, salt control, and efficiency in the upper Yellow River Hetao Irrigation District, aiming to guide these farmers toward scientific irrigation for optimal production. The treatments included (1) CK (conventional flood irrigation; irrigation quota of 810 mm); (2) W1 (low-volume drip irrigation; irrigation quota of 360 mm); (3) W2 (medium-volume drip irrigation; irrigation quota of 450 mm); and (4) W3 (high-volume drip irrigation; irrigation quota of 540 mm). Each treatment was replicated 3 times, totaling 12 plots arranged in a randomized complete block design. The plot size was 20 m × 20 m².

We developed the fertilizer application based on conventional nitrogen (N), phosphorus (P₂O₅), and potassium (K₂O) fertilization practices for maize used by local farmers. For the CK treatment, urea, diammonium phosphate, and compound fertilizer were applied as basal fertilizers at a ratio of N:P₂O₅:K₂O = 400:200:225 (where 65% of N was applied as basal fertilizer and 35% as top dressing, kg ha⁻¹), immediately followed by plowing to a depth of 20–25 cm. The remaining urea was split and applied twice according to the fertilizer demand during the maize growth stages. For the drip irrigation treatment with integrated water and fertilizer (Qiyuan Biotechnology Co. Ltd., Yinchuan, China), a specialized water-soluble maize fertilizer with a nutrient composition of 24–12–14 (representing a mixed ratio of 24% nitrogen, 12% phosphorus, and 14% potassium) was used. The maize was irrigated ten times during the growth period, with fertilizer applied via drip irrigation seven times, matching the total fertilizer application of the flood irrigation treatment. Specific field water and fertilizer management is detailed in

Table 2. Agronomic management schedule of irrigation.

Growth Period	Irrigation Water Volume (mm)				Drip Irrigation Fertilizer Application Ratio (%)
	CK	W1	W2	W3
Seedlings (VE)	0	36	45	54	0
Seedling stage (V1)	180	43	54	65	22
Erupting stage (V4)	0	22	27	32	16
Small trumpet period (V6)	0	47	59	70	14
Big trumpet period (V12)	200	47	59	70	14
Tasseling period (VT)	0	29	36	43	0
Flowering period (R1)	280	29	36	43	12
Grouting period (R2)	0	50	63	76	12
Milk ripening period (R3)	150	36	45	54	10
Wax ripening period (R4)	0	22	27	32	0
Total	810	361	451	539	100

.

2.3. Sample Collection and Analysis

2.3.1. Soil Sample Collection and Analysis

Soil samples were collected at three distinct intervals: 10 September 2021, 13 September 2022 and 15 September 2023. These samples were obtained during the wax maturity stage (R4) of maize using a soil auger, ring cutter, and aluminum box. As depicted in Figure 1A, a random drip head was selected as the center point within each plot for each sampling period. Soil samples were taken at horizontal distances of 0, 10, 20, 30, 40, and 50 cm, and vertical distances of 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 cm from the drip heads using an auger soil screw with a diameter of 4 cm and a height of 15 cm. A total of 60 samples were collected from each sampling point. In the CK treatment, 60 soil samples were randomly collected between maize plants in narrow rows.

The soil samples in aluminum boxes were dried at 105 °C to constant weight to determine the soil moisture content. The remaining soil samples were air–dried, sieved, and then used to prepare soil suspensions at a soil-to-water ratio of 1:5. The electrical conductivity (EC) of the soil suspensions was measured using a conductivity meter (DDS-307A, Shanghai Leimagnet Co., Ltd., Shanghai, China) [24], and the total salt content of the soil was calculated using Equation (1) [25]:

Soil total salt content (g kg⁻¹) = 0.1609X² + 2.9176X − 0.094

(1)

where X represents the soil electrical conductivity at a soil-to-water ratio of 1:5 in dS m⁻¹. The soil desalting rate (SDR) was calculated using Equation (2):

$$\mathrm{SDR} ={\displaystyle \frac{{\mathrm{S}}_1-{\mathrm{S}}_2}{{\mathrm{S}}_1}} \times 100\%$$

(2)

where SDR represents the desalting rate (%), S₁ is the total salt content of the soil before the maize growth period, and S₂ is the total salt content of the soil after the maize growth period.

To measure the concentrations of the eight primary ions (Ca²⁺, K⁺, Na⁺, Mg²⁺, CO₃²⁻, HCO₃⁻, SO₄²⁻, Cl⁻), atomic absorption spectroscopy (AAS) was employed for cations, and ion chromatography was used for anions. Soil samples were prepared by extracting a portion of the air-dried, sieved soil with deionized water, and the resulting solution was filtered through a 0.45 µm filter. The concentrations of Ca²⁺, K⁺, Na⁺, and Mg²⁺ were measured using an atomic absorption spectrophotometer (AA-6880, Shimadzu Co., Ltd., Kyoto, Japan). Calibration curves for each ion were prepared using certified standards. Quality control was ensured by running standards and blank samples periodically during analysis. Anions (CO₃²⁻, HCO₃⁻, SO₄²⁻, Cl⁻) were analyzed using ion chromatography (ICS-5000+, Thermo Fisher Scientific Co., Ltd., Waltham, MA, USA) equipped with an anion-exchange column (Dionex IonPac AS18). The chromatographic conditions were optimized for accurate separation and detection of the target anions, with appropriate calibration standards used for each ion. Soil samples were also tested for alkaline hydrolysable nitrogen, available phosphorus, and rapidly available potassium using the alkali diffusion method, molybdenum antimony colorimetry, and flame photometry, respectively [26].

2.3.2. Plant Sample Collection and Analysis

After maize maturity, three maize plants were randomly selected from each plot to measure plant height and stem diameter. Plant height was measured from the base of the plant to the tip of the tassel using a measuring tape, while stem diameter was measured at the second internode using a caliper for precise readings. Subsequently, the entire plants were collected and transported to the laboratory, where they were dried at 70 °C to constant weight. The aboveground dry matter and thousand-grain weight were determined to calculate grain yield. Water use efficiency (WUE) during the maize growth period was calculated using Equation (3) [27]:

WUE = GY ET⁻¹

(3)

where WUE represents the water use efficiency during the maize growth period (kg (ha·mm)⁻¹), GY is the grain yield per unit area (kg ha⁻¹), and ET is the total water consumption during the maize growth period (mm), calculated using the field water use balance equation [27],

ET = I + P + Δθ − R − L − E + S

(4)

where ET refers to the amount of maize transpiration (mm) and I represent the irrigation amount (mm). P refers to precipitation, measured using a field rain gauge (mm). Δθ denotes the change in soil water storage from sowing to harvest, estimated through spatially weighted averaging (mm). The groundwater contribution is represented by G (mm), while R signifies surface runoff (mm). The groundwater leakage, L, is quantified using a soil seepage monitoring device (mm), and E represents surface water evaporation, monitored with a micro-evaporimeter (mm). S, which denotes the contribution of groundwater to soil moisture (mm), is measured using soil moisture sensors. However, due to the relatively flat topography of the experimental site and an average maize root depth of 60 cm, along with groundwater fluctuations ranging between 1.9 and 3.1 m during the irrigation season and 5 and 6 m during the non-irrigation season, the influence of surface runoff (R) and groundwater contribution (S) was considered negligible and thus excluded from the analysis.

2.4. Data Analysis

Basic calculations and graphical representations were performed using Microsoft Excel 2016 (Microsoft Corporation, Redmond, WA, USA) and Origin 18.0 software (OriginLab Corporation, Northampton, MA, USA, version 18.0, https://www.originlab.com/, accessed on 1 August 2024). One-way analysis of variance (ANOVA) was conducted using SPSS 19.0 (IBM Corporation, Armonk, NY, USA, version 19.0, https://www.ibm.com/products/spss-statistics, accessed on 1 August 2024), and Duncan’s multiple range test was used to compare the significant differences between treatments. The significance level was set at p ≤ 0.05. All data in the tables are presented as the mean ± standard deviation of three replicates.

3. Results

3.1. Influence of Integrated Drip Irrigation and Fertilization on Soil Moisture Distribution in Saline–Alkali Soil

As depicted in Figure 2, clear distinctions emerged in the spatial distribution of soil moisture across different treatments over time. Under conventional high-volume flood irrigation (CK), soil moisture exhibited irregular distribution across various soil strata, indicating non-uniform water penetration. In contrast, the treatments utilizing drip irrigation (W1, W2, and W3) demonstrated a more defined moisture distribution pattern. The highest soil moisture was consistently concentrated at a depth of 100 cm directly beneath the drip emitters, with moisture levels diminishing both radially and vertically from this point. Furthermore, soil moisture at equivalent depths increased progressively over the years as cultivation continued. By maize maturity in September 2022, the rhizosphere (0–40 cm) showed a marked rise in water content. Specifically, water content increased by 5.08% to 18.76% in W1, 5.35% to 25.99% in W2 (p < 0.05), and by a certain percentage in W3 relative to CK.

This moisture accumulation trend continued into the third year (September 2023), with an even more pronounced expansion of the wetted zone in the drip irrigation treatments (W1, W2, and W3). Soil moisture content escalated significantly with increasing irrigation volumes across the treatments. The W1 treatment ranged from 15.19% to 22.83%, W2 from 15.53% to 23.37%, and W3 from 15.79% to 23.90% (p < 0.05), highlighting the efficacy of higher irrigation quotas. Among the treatments, W3 exhibited the highest soil moisture content, followed by W2 and W1. As the soil depth increased to 60–100 cm, moisture levels gradually stabilized across all treatments. However, W3 and W2 consistently maintained the highest moisture content, whereas W1 and CK lagged behind.

3.2. Influence of Integrated Drip Irrigation and Fertilization on Soil Salt Distribution in Saline–Alkali Soil

3.2.1. Differential Distribution of Soil Salt Profiles

Figure 3 depicts the dynamic changes in soil salinity spatial distribution, reflecting a decline in soil EC over successive planting years, thus indicating the migration of soil salts through the soil profile. In the CK treatment, soil salts were unevenly distributed, showing inadequate leaching of salts from the surface. Conversely, the drip irrigation treatments (W1, W2, and W3) displayed a more consistent downward leaching pattern, where salts were gradually flushed from the upper soil layers as a result of continuous water infiltration.

After three years of drip irrigation, a noticeable desalination zone emerged around the drip emitter, signifying efficient salt leaching. By the end of the maize growing season in 2022, the EC values in the 0–40 cm soil layer had decreased by 3.42−19.53% in W1, 4.98–21.06% in W2, and 3.39–22.53% in W3 compared to CK (p < 0.05). This downward salt movement continued through 2023, with further expansion of the desalination zone in the rhizosphere. By maize maturity in 2023, EC values in the 0–40 cm layer were 9.63–25.10% lower in W1, 15.37–25.85% lower in W2, and 18.16–25.93% lower in W3 compared to CK (p < 0.05), clearly demonstrating the enhanced salt leaching effect facilitated by drip irrigation.

The results also show that drip irrigation significantly reduced soil conductivity compared to flood irrigation, with the extent of reduction directly proportional to the irrigation quota. Higher irrigation volumes (W2 and W3) were more effective in leaching salts from the surface soil into deeper layers. Furthermore, a clear trend of increasing salt leaching into the deeper soil strata (40–100 cm) was observed, particularly in the W3 treatment, indicating that drip irrigation not only improves soil moisture distribution but also plays a crucial role in mitigating salt accumulation in the root zone.

3.2.2. Soil Desalination

Different irrigation methods significantly impacted soil desalination.

Table 3. Soil desalination rate in saline–alkali soil under the water-saving irrigation model.

Years	Soil Depth	Treatment
	(cm)	CK	W1	W2	W3
2021	0–20	2.42 ± 2.09a B	20.44 ± 2.04a A	17.48 ± 5.60a A	16.81 ± 7.14a A
	20–40	6.46 ± 9.86a A	7.78 ± 3.22b A	2.80 ± 3.37b A	−1.44 ± 0.48b A
	40–60	8.05 ± 8.31a A	2.27 ± 5.95b A	1.32 ± 5.49b A	2.47 ± 6.06b A
	60–80	4.34 ± 3.40a A	1.48 ± 5.17b A	−0.29 ± 5.12b A	5.76 ± 5.77ab A
	80–100	−2.13 ± 2.17a B	2.61 ± 0.73b A	0.06 ± 0.31b A B	2.11 ± 1.02b A
	Average annual SDR	3.83 ± 3.66	6.92 ± 2.16	4.27 ± 2.24	5.14 ± 3.10
2022	0–20	12.78 ± 3.00a B	23.14 ± 2.56a A	25.96 ± 2.51a A	24.96 ± 3.39a A
	20–40	7.54 ± 8.89ab A	12.20 ± 2.67b A	14.71 ± 1.78b A	11.67 ± 2.96b A
	40–60	0.02 ± 2.15bc C	7.86 ± 0.22bc A	3.61 ± 1.02c B	0.95 ± 0.13c BC
	60–80	5.29 ± 3.51abc A	4.40 ± 5.01c A	4.63 ± 4.66c A	6.22 ± 4.84c A
	80–100	−3.06 ± 2.42c B	4.24 ± 0.26c A	5.43 ± 0.09c A	6.05 ± 0.29bc A
	Average annual SDR	4.51 ± 2.79	10.37 ± 1.99	10.87 ± 1.73	9.97 ± 2.05
2023	0–20	10.54 ± 1.18a B	27.77 ± 2.24a A	31.62 ± 1.91a A	30.51 ± 2.45a A
	20–40	2.33 ± 6.78ab B	20.45 ± 4.11a A	24.21 ± 4.36b A	20.93 ± 6.51b A
	40–60	−5.60 ± 3.10b B	6.93 ± 4.53b A	9.60 ± 0.90c A	10.14 ± 0.21c A
	60–80	6.11 ± 9.90ab A	−2.13 ± 2.76b A	−0.45 ± 1.39d A	3.43 ± 0.07c A
	80–100	−0.39 ± 1.51ab A	−12.82 ± 3.68c B	−13.72 ± 0.62e B	−9.82 ± 1.68d B
	Average annual SDR	2.60 ± 3.75	8.04 ± 0.95	10.25 ± 1.49	11.04 ± 2.62
Three-year average SDR		3.65 ± 3.21	8.44 ± 1.77	8.46 ± 1.98	8.72 ± 2.59

Notes: Different lowercase letters in the same row for a particular soil layer indicate significant differences between treatments (p < 0.05), while different uppercase letters in the same column for a particular irrigation mode indicate significant differences between different soil layers (p < 0.05).

shows that the desalination effect varied among the four treatments in the 0–40 cm soil layer during the harvest seasons from 2021 to 2023. Under drip irrigation (W1, W2, and W3), soil desalination increased gradually with successive planting years, while salt accumulation was observed in the 60–100 cm soil layer, indicating salt migration with soil solution under drip irrigation. Although the soil desalination rate in the 0–20 cm soil layer under flood irrigation (CK) treatment varied between 2.33% and 10.54% (p < 0.05), with a decreasing trend in total salinity, the desalination amplitude was smaller than that of drip irrigation, and the salinity of the surface soil layer (0–20 cm) was significantly higher than under drip irrigation.

Drip irrigation treatments (W1, W2, and W3) demonstrated increased desalination rates with higher irrigation quotas, achieving average desalination rates of 8.04%, 10.25%, and 11.04%, respectively, by September 2023. In contrast, the average desalination rate under flood irrigation was 2.60% (p < 0.05). Soil desalination exhibited a strong regularity in its change characteristics, with desalination decreasing with increasing soil depth. Salt accumulation was observed in the 40–60 cm soil layer under flood irrigation, whereas under drip irrigation, salt accumulation occurred in the 60–80 cm soil layer. This indicates that drip irrigation significantly reduced the salt content of the surface soil and exhibited a delayed desalination effect in deeper soil layers compared to conventional flood irrigation.

3.2.3. Soil Ion Distribution Profiles

As presented in Figure 4, Soil samples collected on 15 September 2024 were analyzed for eight ion measurements, and significant differences in soil ion concentrations were found between irrigation patterns after three consecutive years of experimentation.

Cation concentrations (Ca²⁺, K⁺, Na⁺, Mg²⁺) in the soil profiles decreased with increasing soil depth. Compared with traditional flood irrigation, the drip irrigation treatments exhibited lower levels of Ca²⁺, K⁺, and Na⁺, following the pattern W1 > W2 > W3. Under the CK treatment, the soil K⁺ and Na⁺ concentrations in the 0–40 cm soil layer were 20.71% to 79.50% (K⁺) and 4.84% to 78.29% (Na⁺) higher compared with the drip irrigation treatments (p < 0.05). Conversely, the distributions of Ca²⁺ and Mg²⁺ were minimally affected by irrigation modes owing to their strong adsorption capacity in the soil, making them less mobile with water. However, K⁺ and Na⁺, with weaker adsorption capacities, were more prone to migration with water. Therefore, increasing irrigation quotas led to a significant reduction in K⁺ and Na⁺ concentrations in the soil, while the decrease in Ca²⁺ and Mg²⁺ concentrations was less pronounced. Notably, given the larger hydration radius of Na⁺ compared with K⁺, increasing irrigation led to a greater decrease in Na⁺ concentration.

Anion concentrations (CO₃²⁻, HCO₃⁻, SO₄²⁻, Cl⁻) increased with soil depth. Compared with the surface soil (0–20 cm), the deep soil (60–100 cm) exhibited an increase in anion concentrations ranging from 81.82% to 572.3% (CO₃²⁻); 4.49% to 77.70% (HCO₃⁻); 21.64% to 633.8% (SO₄²⁻); and 1.96% to 303.9% (Cl⁻). The soil CO₃²⁻, HCO₃⁻, SO₄²⁻, and Cl⁻ concentrations under the CK treatment were significantly higher than those under drip irrigation (p < 0.05), with the overall trend being CK ≥ W1 ≥ W2 ≈ W3. This indicates that drip irrigation significantly reduced the soil anion concentrations.

3.2.4. Distribution of Soil Nutrients

Table 4. Effective nutrient content of saline–alkali soil under the water–fertilizer integrated drip irrigation model.

Soil Layer (cm)	Irrigation Mode	Alkaline Hydrolyzable N (mg·kg−1)	Available P (mg·kg−1)	Available K (mg·kg−1)
0–20	CK	36.22 ± 1.94c A	31.37 ± 5.51b A	202.81 ± 14.06a A
	W1	48.42 ± 1.07a A	47.49 ± 13.6a A	195.16 ± 16.94ab A
	W2	43.58 ± 1.22b A	54.29 ± 5.03a A	149.44 ± 24.74b A
	W3	46.64 ± 2.36ab A	61.29 ± 2.27ab A	198.16 ± 19.72ab A
20–40	CK	21.23 ± 0.88b B	10.23 ± 3.75a B	139.19 ± 21.85a B
	W1	33.43 ± 3.15a B	26.93 ± 21.49a B	143.11 ± 8.69a B
	W2	37.45 ± 1.75a B	30.74 ± 5.91a B	153.49 ± 22.51a A
	W3	34.56 ± 3.76a B	33.39 ± 6.37a AB	153.96 ± 7.89a AB
40–60	CK	15.07 ± 3.63b C	1.61 ± 0.34b C	122.20 ± 4.85a B
	W1	21.23 ± 1.99a C	3.67 ± 0.53ab C	144.12 ± 20.86a B
	W2	22.05 ± 1.21a C	3.24 ± 1.51ab C	145.03 ± 7.71a A
	W3	18.55 ± 1.75ab C	3.9 ± 0.42a B	143.85 ± 21.87a AB
60–80	CK	8.58 ± 0.52b D	1.03 ± 0.21b C	129.38 ± 2.12a B
	W1	19.72 ± 2.14a C	3.51 ± 0.05a C	133.63 ± 12.55a B
	W2	21.82 ± 1.13a C	2.94 ± 0.99ab C	149.6 ± 10.28a A
	W3	19.08 ± 0.88a C	3.18 ± 1.09a B	152.62 ± 14.89a B
80–100	CK	8.40 ± 1.40b D	0.53 ± 0.24c C	131.53 ± 9.76a B
	W1	22.75 ± 0.93a C	1.9 ± 0.59ab C	155.6 ± 16.63a AB
	W2	21.58 ± 1.73a C	1.46 ± 0.1bc C	151.69 ± 23.56a A
	W3	20.65 ± 0.7a C	2.84 ± 0.54a B	152.65 ± 38.74a AB

Notes: Different lowercase letters in the same row for a particular soil layer indicate significant differences between treatments (p < 0.05), and different capital letters in the same column for a particular irrigation pattern indicate significant differences between soil layers (p < 0.05).

illustrates the pronounced differences in soil nutrient profiles across varying irrigation strategies after three consecutive years of experimentation (September 2023). In general, nutrient concentrations exhibited a distinct decline when increasing the soil depth from 0 to 100 cm. Within the plow layer (0–20 cm), the combined drip irrigation and fertilization model markedly enhanced alkaline hydrolysable N and available P levels compared to conventional flood irrigation. While the available K content under flood irrigation exceeded that of the integrated drip irrigation system, this difference did not reach statistical significance. Despite uniform fertilization being applied across all treatments, nutrient availability followed the trend W3 > W2 > W1 under drip irrigation, suggesting that irrigation volume directly modulated nutrient retention and distribution in the soil profile. Moreover, nutrient levels under traditional flood irrigation were consistently lower than those observed with integrated drip irrigation, underscoring the critical role of the irrigation method in governing soil fertility. The integrated drip irrigation system significantly bolstered nutrient accumulation, particularly in the topsoil, enhancing the overall soil fertility and potential crop productivity in saline–alkali soils.

3.3. Impact of Integrated Drip Irrigation and Fertilization on Maize Growth

3.3.1. Maize Growth and Yield

Table 5. Maize growth and yield under the water–fertilizer integrated drip irrigation model.

Years	Irrigation Mode	Plant Height	Stem Diameter	Aboveground Biomass	Grain Yields	Increase in Yield Compared to CK
		(cm)	(mm)	(kg ha−1)	(kg ha−1)	(%)
2021	CK	271.1 ± 10.00a	17.66 ± 1.17a	54,037 ± 3317a	9959 ± 65.80b	-
	W1	278.3 ± 12.25a	17.95 ± 2.17a	57,387 ± 1969a	11,243 ± 416.5ab	12.88 ± 3.51ab
	W2	285.0 ± 36.67a	18.24 ± 0.52a	58,856 ± 9658a	10,673 ± 527.8ab	6.49 ± 5.27b
	W3	319.2 ± 20.50a	18.76 ± 0.60a	60,286 ± 1032a	11,686 ± 1065a	16.59 ± 10.63a
2022	CK	276.0 ± 23.74a	18.74 ± 1.80a	54,856 ± 1354b	10,609 ± 1178b	-
	W1	286.2 ± 15.05a	19.81 ± 0.18a	58,973 ± 1400a	11,741 ± 406.9ab	11.55 ± 12.89b
	W2	285.5 ± 23.07a	19.33 ± 2.11a	58,613 ± 1888ab	11,984 ± 137.2ab	15.98 ± 1.33ab
	W3	324.9 ± 20.07a	20.01 ± 2.68a	61,356 ± 1201a	12,578 ± 692.4a	21.73 ± 6.70a
2023	CK	287.8 ± 13.42a	19.70 ± 0.23a	57,299 ± 1804b	10,472 ± 481.8b	-
	W1	292.2 ± 3.42a	19.54 ± 1.05a	60,274 ± 1477ab	12,034 ± 147.1a	15.06 ± 5.13ab
	W2	288.4 ± 23.47a	20.42 ± 0.51a	59,216 ± 1961ab	12,349 ± 356.4a	12.02 ± 3.23b
	W3	327.1 ± 16.16a	19.90 ± 1.34a	61,801 ± 976.0a	12,975 ± 651.7a	17.70 ± 5.91a

Notes: Different lowercase letters in the same column indicate significant differences between treatments (p < 0.05).

highlights that variations in irrigation methods had no significant impact on maize plant height, stem diameter, or aboveground biomass in saline–alkali soil. However, drip irrigation treatments significantly boosted maize grain yields. Compared to the control treatment using conventional flood irrigation (CK), grain yields under the drip irrigation modes increased by 12.88%, 6.49%, and 16.59% for W1, W2, and W3 in 2021, respectively. This trend persisted in 2023, with yield increases of 15.06%, 12.02%, and 17.70% for W1, W2, and W3, respectively (p < 0.05).

Although the differences among the drip irrigation treatments (W1, W2, W3) were not statistically significant, the yield growth rates compared to CK showed substantial improvement. W3 exhibited a yield increase of 4.12% to 7.79% higher than W1, indicating that higher irrigation quotas resulted in improved maize yields. This trend demonstrates that drip irrigation substantially enhances maize production, with greater irrigation volumes yielding greater gains.

3.3.2. Maize Transpiration and Water Use Efficiency

Table 6. Maize transpiration and water use efficiency under the water–fertilizer integrated drip irrigation mode.

Years	Treatment	I	P	ΔΘ	L	E	(L + E) (I + P)−1	ET	WUE
		(mm)	(mm)	(mm)	(mm)	(mm)	(%)	(mm)	(kg ha−1 mm−1)
2021	CK	810	189	40.96a	20.40a	436.2a	45.70a	583.4a	17.13b
	W1	360	189	38.33a	10.89b	140.8b	27.62b	435.7c	25.84a
	W2	450	189	46.50a	12.92b	164.8b	27.82b	507.7b	21.05b
	W3	540	189	45.65a	15.30ab	185.8b	27.59b	573.5a	20.38b
2022	CK	810	192	48.77b	19.58a	415.8a	43.45a	615.4a	17.33c
	W1	360	192	51.22b	11.08b	135.1b	26.48b	457.1c	25.69a
	W2	450	192	52.99ab	12.42b	158.2b	26.57b	524.4b	22.86ab
	W3	540	192	57.09a	14.70ab	180.8b	26.70b	593.6a	21.18b
2023	CK	810	195	50.16b	18.79a	399.5a	41.62a	636.9a	16.52c
	W1	360	195	54.98ab	10.63b	129.7b	25.28b	469.7c	25.63a
	W2	450	195	57.42a	11.94b	151.8b	25.39b	538.7b	22.93b
	W3	540	195	58.69a	14.13ab	173.4b	25.51b	606.2a	21.40b

Notes: ET represents maize transpiration, I represent total irrigation during the maize growth period, P represents precipitation during the maize growth period, L represents total underground leakage loss of soil water from the root zone during the maize growth period, E represents surface water evaporation, and S represents groundwater. Different lowercase letters in the same column indicate significant differences between treatments (p < 0.05).

illustrates that during the experimental period, soil water storage (ΔΘ) was significantly higher under the drip irrigation treatments (W2, W3) compared to CK in 2022 and 2023, except for 2021, where no significant differences in ΔΘ were observed among the treatments. Specifically, W3 showed a significantly higher ΔΘ by 4.28−16.82% in 2022, and both W2 and W3 were significantly higher, by 9.29−19.22% and 11.57–22.03%, than CK in 2023. Surface evapotranspiration (E) was significantly higher in CK than in the drip irrigation treatments, ranging from 130.4 to 209.9%, due to extensive surface irrigation (p < 0.05). However, there were no significant differences among the drip irrigation treatments, which varied between 140.8 and 185.8 mm, 135.1 and 180.8 mm, and 129.7 and 173.4 mm over the three years, respectively. Notably, subsurface seepage and surface evaporation together accounted for 41.62–45.70% of irrigation water and rainfall in CK, significantly higher than in W1 (25.28–27.62%), W2 (25.39–27.82%), and W3 (25.51–27.59%). In 2022 and 2023, drip irrigation treatments significantly improved water use efficiency compared to conventional flood irrigation. Overall, under HF integrated drip irrigation, water and fertilizer supply better met the growth demands of maize, reduced field evaporation, and simultaneously improved maize water use efficiency.

4. Discussion

Three consecutive years of field trials demonstrated significant differences in soil water content under different irrigation patterns. Drip irrigation consistently resulted in higher soil moisture compared to traditional flood irrigation, with moisture levels increasing as irrigation quotas were raised, aligning with findings by Liang et al. [28]. Moreover, similar findings have been reported in semi-arid regions of Africa, where drip irrigation has been shown to enhance water retention in highly saline–alkali soil [29]. Likewise, studies in India’s semi-arid regions have demonstrated increased crop yields with drip irrigation despite challenging climatic conditions [30]. These findings suggest that the effectiveness of drip irrigation extends beyond China, reinforcing its potential for broader agricultural applications globally. The increased quotas under drip irrigation effectively replenished water losses in shallow soil layers due to high evapotranspiration, maintaining higher moisture levels. Moreover, drip irrigation promoted uniform and stable water infiltration, enhancing moisture accumulation in deeper soil layers [31,32]. This deeper infiltration is influenced by several factors, including soil texture, structure, and hydraulic conductivity, which allow for gradual percolation and moisture retention at depth. These processes are optimized by drip irrigation’s ability to deliver water directly to the root zone, reducing surface evaporation and preventing soil compaction, thereby sustaining higher moisture content in the sub soil. In the Middle East, the implementation of drip irrigation systems has not only improved water distribution but also enhanced agricultural sustainability under severe water scarcity [33]. Conversely, traditional flood irrigation involves large irrigation volumes per application, leading to the frequent lateral movement of irrigation water on the surface and increasing the susceptibility of subsurface flow to clogging in upper soil layers, disrupting the soil structure and hindering water infiltration, and resulting in uneven soil moisture distribution [34].

Surface evaporation moves the soil solution upward, driven by capillary action, which draws water and dissolved salts toward the surface through the narrow pores in the soil matrix. This capillary movement enhances salt accumulation in the upper soil layers, particularly in arid regions. Simultaneously, transpiration by plants causes water uptake through the roots, which concentrates salts around the root zone. The process of ion exchanges further influences salt movement, as cation exchange sites in the soil attract and retain positively charged ions, such as Na⁺ and calcium Ca²⁺, affecting the redistribution of salts within the soil profile. This combination of capillary action and ion exchange contributes to saline–alkali stress, ultimately affecting crop growth [35]. Consistent with the findings of Dong et al. [36], we found that soil salinity under drip irrigation was significantly lower than that under traditional flood irrigation in the 0–40 cm soil layer (Figure 3). This is because salts in the soil solution are dissolved by percolation water under drip irrigation, and with frequent high-frequency subsurface infiltration, a desalination effect is formed in the surface soil layer. In the 60–100 cm soil layer, salt movement may have been impeded because of increased soil moisture and reduced porosity, resulting in the gradual accumulation and an overall higher vertical distribution pattern of salt in the lower layers. This occurs because higher bulk density decreases soil porosity, limiting the movement of water and dissolved salts. The reduced pore space restricts both water infiltration and salt leaching, which slows down the downward migration of salts and causes their retention in these deeper layers. As the soil becomes more compact, it further obstructs the vertical salt movement, leading to greater accumulation of salts in specific soil horizons [37]. It is noteworthy that the surface soil salinity under CK was over double that under high-volume drip irrigation, indicating that flood irrigation failed to form a uniformly effective percolation zone to remove soil salts despite its high irrigation quota, resulting in a poor desalination effect in the surface soil layer, consistent with the findings of Fan et al. [38]. Over time, the accumulation of salts in deeper soil layers poses significant risks to both crop productivity and soil health. As salts continue to build up in the subsoil, they can create osmotic stress, reducing the availability of water to plant roots and leading to inhibited root growth and reduced nutrient uptake. This can result in stunted crops, lower yields, and poor plant health. In addition, persistent salt accumulation can lead to the degradation of soil structure, reducing soil permeability and porosity, which in turn hampers root penetration and water infiltration. Over the long term, these conditions can contribute to soil salinization, making the land less arable and decreasing its overall agricultural productivity.

The desalination effect was most significant in the W3 treatment, whereas the W1 treatment showed lower desalination in the 40–100 mm soil layer, suggesting that lower drip irrigation quotas can leach surface soil salts but have poor desalination effects on deep soil layers. In addition, during the first and second years of the experiment, it could be observed that the desalination effect in the 0–60 cm soil layer under the drip treatment was not significant, but significant soil migration to the deeper soil layer could be observed. By the third year of the experiment (September 2023) when the salinity of the surface soil (0–20 cm) under drip irrigation treatment was significantly lower than that in 2021, the salinity gradually migrated downward to the 40–100 cm soil layer. Therefore, in future efforts to improve irrigation in saline–alkali soil, it may be necessary to appropriately increase irrigation quotas based on soil texture, soil type, and salinity to ensure the effective desalination of deeper soils. Environmental studies in Australia also support this, where large-scale drip irrigation projects have led to substantial reductions in salinity levels in irrigated fields [39].

Soil conductivity changes can be used to characterize soil salinity [40]. This study demonstrates that under drip irrigation conditions, soil salinity gradually migrated to deeper soil layers with the infiltration of irrigation water, and the distribution of salts gradually transitioned from “surface aggregation” to “bottom accumulation” (Figure 3, Table 3). Additionally, in the 40–60 cm soil layer, downward salt movement may have been hindered by factors such as excessive bulk density in deep soil, reduced porosity, and proximity to the groundwater level. Anions in the soil under drip irrigation gradually migrate to deeper soil layers with the percolation water (Figure 4), possibly because soil colloids carry negative charges because of cation exchange and the deprotonation of surface hydroxyl groups. In the process of cation exchange, Na⁺ and Ca²⁺ exhibit differential movement. Na⁺, with their smaller charge and hydration radius, are weakly adsorbed by soil colloids, and are therefore more mobile, allowing them to migrate downward more readily with percolating water. In contrast, Ca²⁺, which have a larger charge and hydration radius, are more strongly attracted to the negatively charged sites on soil colloids, leading to greater retention in the upper soil layers. This difference in cation exchange behavior contributes to the distinct movement patterns of Na⁺ and Ca²⁺ within the soil profile [41].

The maize varieties used in this experiment were suitable for both silage and forage. Parameters such as plant height, stem thickness, and aboveground biomass represent the basic growth status of maize, with aboveground biomass indicating the total yield for silage. In this study, plant height and stem thickness of maize were assessed under different irrigation methods (Table 5). Although there were no significant differences in plant height and stem thickness across treatments, this is likely because drip irrigation enhances grain filling and kernel development by providing consistent moisture to the root zone, thereby increasing the overall grain weight and spike yield, which contribute significantly to the aboveground biomass. Drip irrigation significantly increased the aboveground biomass and grain yield of maize in the second year of the experiment compared to conventional flood irrigation. This aligns with the findings of Suat et al. [42], which showed that maize yield increased with irrigation. Similarly, our results indicate that maize grain yield increased with higher drip irrigation quotas, with the most substantial yield enhancement observed under W3 drip irrigation. Drip irrigation offers notable potential economic benefits through improved water-use efficiency and increased crop yield. By delivering water directly to the root zone, it minimizes waste through evaporation and runoff, leading to significant water savings compared to conventional flood irrigation. This reduction in water usage translates into lower input costs, while the higher yields and improved crop quality observed under drip irrigation contribute to enhanced profitability for farmers. In California, USA, the widespread adoption of drip irrigation led to significant water savings [43]. Furthermore, the ability of drip irrigation to deliver water-soluble fertilizers more precisely allows for better nutrient uptake by the crops, promoting consistent growth and reducing the likelihood of nutrient leaching, thus enhancing crop quality parameters such as kernel size, starch content, and plant robustness. Moreover, the environmental impact of drip irrigation is also worth noting. Compared to conventional flood irrigation, drip irrigation reduces the volume of water applied, decreasing energy consumption and thus contributing to lower greenhouse gas emissions. The overall improvement in water and nutrient use efficiency lessens the risk of soil degradation, waterlogging, and contamination of surrounding water bodies, making it a more sustainable option. Additionally, the enhanced water efficiency and increased yield potential of drip irrigation enable faster cost recovery, as the higher productivity and quality of the maize produced can offset the initial investment in the irrigation infrastructure. In this way, drip irrigation not only improves maize yield, but also offers long-term economic and environmental benefits [44].

Water plays a critical role in plant growth, and enhancing water use efficiency in arid regions is pivotal for improving agricultural productivity [45]. In this study, the W1 treatment demonstrated the highest water use efficiency under drip irrigation, significantly surpassing the CK treatment, which exhibited almost four times the surface evaporation of W1 (Table 6). The increased efficiency directly contributed to corn yield improvements: W1, W2, and W3 treatments achieved yield increases of 9.64–19.84%, 9.08–15.71%, and 10.94–21.90%, respectively, over CK. These gains are attributed to the ability of drip irrigation to minimize water loss through evaporation and runoff, ensuring better hydration of the root zone and promoting more consistent plant growth. This also reduced drought stress and improved nutrient uptake, ultimately enhancing overall crop performance. Conventional flood irrigation, by contrast, applies large volumes of water across the field, resulting in extensive surface evaporation and surface water runoff, which degrades soil structure over time. This can lead to the formation of cracks, facilitating the upward movement of salts to the surface during winter, thereby re-salinizing soils [46]. Drip irrigation, however, delivers water in precise, small amounts, preventing surface water accumulation and maintaining soil structure. The integration of fertilization with high-frequency (HF) drip irrigation also improved nutrient delivery, reducing phosphorus fixation and nitrogen volatilization, which further enhanced water and nutrient use efficiency [47]. Despite these benefits, the study does have limitations. The specific characteristics of saline soils, such as their heterogeneous texture and the tendency for salts to accumulate in deeper layers, can complicate long-term management. Moreover, the results may vary under different climate conditions or soil types, indicating the need for further research to explore these variables and refine drip irrigation strategies for broader applications.

5. Conclusions

The integration of drip irrigation and fertilization technology in saline–alkali soils of northern Ningxia effectively mitigates soil moisture losses from evaporation and transpiration, ensuring higher moisture retention. High-volume drip irrigation (W3) demonstrated superior efficacy, significantly enhancing moisture levels in the 0–20 cm and 60–100 cm soil layers. This method promotes uniform salt leaching, shifting salt accumulation from the surface to subsurface layers, thereby alleviating saline–alkali stress on crops. The study highlights the necessity for tailored irrigation strategies based on specific soil characteristics to optimize soil desalination. These findings underscore the innovative potential of combining high-volume drip irrigation with precise fertilization to boost crop productivity while fostering environmental sustainability in saline–alkali regions. Future research should prioritize the long-term monitoring of soil and crop responses under varying irrigation regimes to refine these practices. Developing clear guidelines for farmers will be essential in translating these insights into sustainable agricultural practices, thereby advancing high-quality development and ecological restoration in saline–alkali areas.