Effects of Zeolite Amendment and Saline Irrigation Water on Soil Properties and Seedling Establishment in Arid Conditions

1.Introduction

Approximately 2.1 billion people inhabit the world's dryland biomes, where soil degradation, salinity, and freshwater scarcity severely constrain land productivity and ecological stability (Ondrasek et al., 2022; Sani et al., 2023). Iraq exemplifies these compounding pressures: ranked among the five countries most vulnerable to climate change impacts, it faces accelerating desertification driven by declining river flows, rising temperatures, and mismanaged agricultural drainage (Gull et al., 2019; Suzuki et al., 2014). In southern Iraq, the heart of ancient Mesopotamia, the reuse of saline agricultural drainage water has become a real necessity for irrigation and land rehabilitation, given the near-total depletion of freshwater allocations from the Euphrates and Tigris systems. This practice, while pragmatic, imposes severe salt loads on already degraded soils, further undermining the capacity to establish protective vegetation for sand and dust storm (SDS) mitigation.

Salt stress ranks among the most damaging abiotic constraints on plant establishment globally. Soil electrical conductivity (ECe) exceeding 4 dS/m suppresses growth in most glycophytic species, while concentrations of Na⁺ and Cl⁻ beyond critical thresholds disrupt osmotic adjustment, ion homeostasis, and photosynthetic integrity (Berens et al., 2019; He et al., 2023). In the southern Iraqi context, where drainage water EC routinely exceeds 8 dS/m in summer and can surpass 20 dS/m during seasonal flow minima in drainage rivers, only highly tolerant halophytic species are viable candidates for dryland revegetation. The selection of appropriate species and soil management strategies is therefore critical to programme success.

Zeolites, microporous aluminosilicate minerals characterized by a three-dimensional cage-like framework of interconnected SiO₄ and AlO₄ tetrahedra, have attracted growing agronomic interest as multi-functional soil amendments (Munir et al., 2024; Nakhli et al., 2017). Their reversible hydration–dehydration capacity, high cation exchange capacity (CEC; typically 100–200 cmol(+) kg⁻¹), large specific surface area, and ability to adsorb Na⁺ and release plant-essential cations (Ca²⁺, K⁺, Mg²⁺) make them theoretically well-suited to ameliorating saline, low-fertility dryland soils (Ming and Allen, 2001; Javaid et al., 2024). Empirical evidence from controlled and greenhouse studies consistently demonstrates that zeolite addition improves soil water retention (Ibrahim and Alghamdi, 2021), reduces bulk density (Mondal et al., 2021), elevates CEC (Amirahmadi et al., 2022), and enhances the availability of nitrogen, phosphorus, and potassium (Aslan and Arslan, 2024; Szatanik-Kloc et al., 2021). Zeolite application has also been shown to reduce irrigation frequency and total water use by up to 30–50% in horticultural settings, with implications for water-scarce arid systems (Cataldo et al., 2024; Hazrati et al., 2022).

Despite this body of evidence, critical knowledge gaps persist. The great majority of published zeolite studies have used controlled greenhouse conditions with fixed, moderate salinity levels, pre-defined crop species, and short observation windows. Far fewer studies have examined zeolite performance under field conditions involving (i) dynamically fluctuating saline drainage water; (ii) extreme summer EC peaks characteristic of hyper-arid climates; and (iii) woody perennial tree seedlings rather than herbaceous crops. No prior study, to our knowledge, has compared the performance of Prosopis juliflora and Tamarix articulata, two of the most widely advocated halophytic trees for MENA dryland rehabilitation, under simultaneous zeolite amendment and fluctuating drainage water irrigation in the field.

This study addresses these gaps through a first-year field assessment in the hyper-arid Altuba district of southern Thi-Qar Governorate, Iraq. The specific objectives were to: (1) quantify the effects of synthetic zeolite amendment on soil physicochemical and fertility properties under saline drainage water irrigation; (2) determine the influence of zeolite application on irrigation water consumptive use; and (3) compare the salinity tolerance and survival of Sockalsham (P. juliflora) and Athal (T. articulata) seedlings under extreme seasonal salinity stress. We tested the hypotheses that (H1) zeolite would significantly improve soil physical and chemical properties relative to saline irrigation alone; (H2) zeolite would reduce total irrigation water demand by enhancing soil water retention; and (H3) P. juliflora would demonstrate superior survival to T. articulate given its documented halotolerance mechanisms. The findings have direct practical relevance to evidence-based species selection and soil management in sand and dust-storm mitigation revegetation programmes across the Mesopotamian lowlands and analogous dryland settings globally.

2. Materials and Methods

2.1. Study Site

The study was conducted at Altuba district, southern Thi-Qar Governorate, Iraq (31°12'45"N, 45°46'33"E; Figure 1), covering a total area of one hectare. The site was selected as a representative the sources for sand and dust storms (SDS) hotspot: a degraded, previously cultivated area (principally barley) with highly erodible surface soils. The regional climate is hyper-thermic and hyper-arid, characterized by mean annual precipitation below 80 mm, a mean annual temperature of 26°C, and extreme summer maxima frequently exceeding 50°C. Prevailing soil textures are loam (Site 1) and silt loam (Site 2), moderately saline prior to the experiment.

2.2. Zeolite Material

The soil amendment used in this study was a synthetic clinoptilolite-type zeolite supplied by the Natural Resources Limited Company for Agricultural Materials Trading and Manufacturing, Baghdad, Iraq. The material had a particle size range of 1–3 mm, a cation exchange capacity of approximately 180 cmol(+) kg⁻¹, a Si/Al ratio of ~4.5, and a water absorption capacity of approximately 65% of dry weight. A dose of 250 g per seedling, equivalent to approximately 2.5 Mg ha⁻¹ based on the planting density, was thoroughly mixed into the topsoil (0–20 cm) at each planting hole prior to seedling installation. This dose falls within the ergonomically effective range reported in the literature (Nakhli et al., 2017; Sindesi et al., 2023a).

2.3. Experimental Design

The experiment evaluated the survival and associated soil responses of two halophytic tree species, Prosopis juliflora (Sw.) DC. (locally known as Shokalsham) and Tamarix articulata Vahl (locally known as Athal), under :(i) saline irrigation water only (control) ( S2 treatment), and (ii) saline irrigation water combined with zeolite soil amendment (S1 treatment). The study area was divided into two parts (Figure 2), according to the dominant soil types. A total of 30 seedlings per species were planted in three rows of ten, at a spacing of 5 m × 5 m. Zeolite-amended seedlings at rate of 250gm were individually treated at the planting hole. The seedlings were irrigated with saline agricultural drainage water using a drip irrigation system.

The second part S2(Silt Loamy soil) represents the control treatment, to test the impact of using zeolite and saline on soil properties and plant survival. A total of 30 seedlings per species were planted in three rows of ten, at a spacing of 5 m × 5 m. Both sites were Irrigated by applied via a drip system using a water pump with a flow rate of 20 m³ h⁻¹. Irrigation scheduling was triggered when soil moisture sensors indicated depletion of 50% of available soil water at 0–30 cm depth.Irrigation water was sourced from the eastern Al-Furat (Euphrates) drainage river, the only available water supply in the study area. Baseline water quality parameters recorded at the plantation date are presented in Table 1.

Reprehensive surface soil samples were taken from two parts, and common soil properties were determined in the Laboratory prior to seedlings plantation (Table 2), these data were used as a baseline to test the effect of soil amendment on the studied soil properties. At the end of the first growing year, five composite surface soil samples (0–25 cm) were collected from each treatment row for physicochemical analysis.

Table 2 shows the baseline data for the common soil properties determined prior to seedlings plantation collected at depth (0–25 cm) from the selected sites. BD: bulk density; SMC: soil moisture content; ECe: electrical conductivity of saturated paste extract; CEC: cation exchange capacity; OC: organic carbon; TN: total nitrogen; Av-K: available potassium; Av-P: available phosphorus.

2.4. Soil Analytical Methods

At the end of the first growing year, five composite surface soil samples (0–25 cm) were collected from each treatment row for physicochemical and fertility properties analysis. All soil parameters were determined using internationally recognised standard methods. Particle size distribution was determined by the hydrometer method (Keller and Gee, 2006). Soil moisture content (SMC) was measured gravimetrically after oven drying at 105°C for 24 hours (Rasheed et al., 2022). Soil pH was measured in a 1:2.5 soil-to-water suspension (Soil Survey Staff, 2014). Soil organic matter (OC) was quantified by wet oxidation (Walkley and Black, 1934). Cation exchange capacity (CEC) and exchangeable cations were extracted using 1 M ammonium acetate (NH₄OAc) at pH 7.0 (Sumner and Miller, 1996). Electrical conductivity (EC) was determined in a 1:1 soil–water extract. Available phosphorus and potassium were measured by standard colorimetric and flame photometric methods, respectively.

2.5. Monitoring Water Quality Irrigation

Given the marked seasonal variability of the Al-Furat drainage river, irrigation water quality was monitored at four time points across the study year (December 2024, June 2025, September 2025, and November 2025). The EC, pH, and dominant ion concentrations (Na⁺, Ca²⁺, Cl⁻, SO₄²⁻) were measured at each sampling event using standard analytical methods.

2.6. Water Consumptive Use Measurement

Total irrigation water consumptive use for each treatment was calculated by multiplying the pump discharge rate (20 m³ h⁻¹) by the cumulative operating time across all irrigation events over the first year. Irrigation events were logged automatically via the moisture sensor control system. Water use efficiency was expressed as total seasonal water applied per treatment.

2.7. Statistical Analysis

Treatment effects on soil physicochemical properties were assessed using one-way analysis of variance (ANOVA) in SPSS Statistics v.24 (IBM Corp., Armonk, NY). Where significant main effects were detected (p < 0.05), means were separated using the least significant difference (LSD) post-hoc test. Results are presented as means with lowercase letters indicating statistically homogeneous groups (p < 0.05). Seedling survival data are reported as percentage survival calculated from the 30 seedlings planted per species per treatment.

3. Results

3.1. Seasonal Dynamics of Irrigation Water Salinity

Irrigation water salinity varied substantially across the study period, reflecting the seasonal hydrology of the Al-Furat drainage river (Table 3). At the plantation in December 2024, EC was 3.5 dS/m, classified as moderately saline and within the tolerance range of both target species. By June 2025, EC had risen to 8.5 dS/m as upstream water abstraction increased and drainage return flows concentrated. The most critical period occurred in September 2025, when EC peaked at 21.9 dS/m (accompanied by Na⁺ concentrations of 10,550 ppm and Cl⁻ concentrations of 30,800 ppm), representing an extreme ionic stress event coinciding with peak summer temperatures. EC subsequently declined to 9.3 dS/m in November 2025 following seasonal rainfall. This seasonal trajectory established a realistic and ecologically severe salinity stress regime spanning from moderate to extreme, consistent with conditions documented across southern Iraqi drainage systems.

3.2. Effects of Zeolite Amendment on Soil Physical Properties

Table 4 presents mean soil physical property values for all treatments at the end of Year 1. Zeolite amendment significantly increased soil moisture content (SMC) relative to both the pre-plantation control and the saline-irrigation-only treatment (p < 0.05). At Site 1, SMC increased from 6.4% in the control to 10.48% under zeolite + saline irrigation with P. juliflora, a 64% increase. At Site 2, SMC increased from 13.65% (control) to 14.64% under zeolite + T. articulata treatment(Figure 3). The consistently higher SMC in zeolite-amended plots reflects the material's high internal porosity and capacity to retain plant-available water within its aluminosilicate lattice, buffering soil water supply between irrigation events (Ghorbanifar et al., 2022; Karami et al., 2020).

Soil bulk density (BD) declined modestly but significantly (p < 0.05) with zeolite addition, from 1.28 g/cm³ (control, Site 1) to 1.25 g/cm³ (zeolite + P. juliflora treatment) and from 1.34 g/cm³ (control, Site 2) to 1.28 g/cm³ (zeolite + T. articulata treatment)( Figure 4). The reduction in BD is attributable to zeolite's contribution to macro-aggregate formation and increased inter-aggregate porosity, which also improves root penetration and aeration in otherwise compact arid soils (Mondal et al., 2021; Asadi et al., 2021).

3.3. Effects of Zeolite Amendment on Soil Chemical Properties

Zeolite amendment significantly increased soil CEC (Table 5), with the most pronounced response at Site 1, where CEC rose from 15.6 cmol(+) kg⁻¹ (control) to 20.1 cmol(+) kg⁻¹ under zeolite + P. juliflora treatment (+29%; p < 0.05). At Site 2, the increase was modest (25.9 to 26.2 cmol(+) kg⁻¹)( Figure 5), likely because baseline CEC was already relatively high in the silt loam soil. These findings are consistent with the high intrinsic CEC of synthetic clinoptilolite zeolite and its role in increasing the density of cation exchange sites in the soil matrix (Amirahmadi et al., 2022; Ghorbani et al., 2022).

Soil pH declined significantly in zeolite-amended treatments (Figure 6). At both sites, pH decreased by approximately 1.1 units relative to the pre-plantation control, from 8.3–8.4 to 7.1–7.4, bringing values within the range optimal for macronutrient availability. The pH reduction is attributed to the displacement of exchangeable Na⁺ by Ca²⁺ and Mg²⁺ held within zeolite exchange sites, combined with CO₂ production from stimulated microbial activity in the organic-matter-enriched rhizosphere (Sindesi et al., 2023; Nur Aainaa et al., 2018).

3.5. Effects of Saline Irrigation and Zeolite on Salt Accumulation

Saline irrigation without zeolite caused severe soil salt accumulation over the study year. Soil EC increased from 7.4 dS/m (baseline, Site 1) to 16.3 dS/m under saline-only irrigation with P. juliflora, and from 6.1 dS/m (baseline, Site 2) to 21.6 dS/m under saline-only irrigation with T. articulata, representing 2.2- and 3.5-fold increases, respectively (Table 5; Figure 7). These levels far exceed the tolerance thresholds for most agricultural crops (ECe > 4 dS/m) and even challenge recognized halophytes. The dominant salt ions were Na⁺ and Cl⁻ (Table 3), consistent with sodium chloride-dominated drainage water chemistry typical of Mesopotamian irrigation return flows.

3.5. Effects of Zeolite Amendment on Soil Fertility Indicators

Zeolite amendment significantly improved all measured soil fertility indicators (Figures 8–10). Soil organic carbon (SOC) increased markedly in zeolite-amended plots, rising from 0.03% to 0.14% at Site 1 (P. juliflora; +367%) and from 0.04% to 0.09% at Site 2 (T. articulata; +125%), compared with the pre-plantation controls( Figure 8). In saline-only treatments, OC also increased relative to baseline (to 0.09–0.10%), likely reflecting seedling root turnover and leaf litter accumulation, but to a lesser extent than in zeolite-amended plots. The amplified OC accumulation in zeolite treatments reflects the material's role in protecting organic carbon from rapid mineralization by stabilizing soil aggregates and reducing oxidative decomposition under the improved moisture regime (Aminiyan et al., 2015; Cairo et al., 2017).

Total nitrogen (TN) increased from 7.7 mg/kg (control, Site 1) to 10.0 mg/kg under zeolite + treatment (+30%), while available potassium rose from 116.4 ppm to 134.2 ppm (+15%). Available phosphorus showed smaller but consistent improvements across both sites( Figure9). These nutrient enhancements are mechanistically linked to (i) the high CEC of zeolite providing additional adsorption sites for NH₄⁺, retarding its leaching below the root zone and enabling slow release as soil nitrate concentrations decline (Behzadfar et al., 2017; Aslan and Arslan, 2024); and (ii) the pH reduction toward near-neutral values, which optimizes phosphorus and micronutrient availability through reduced anion competition and improved microbial mineralization rates.

Generally, the results of this study (Figures 9,10 and 11) emphasized that the application of zeolite and using saline irrigation water led to a significant increase (p > 0.005) in level viability of Phosphorous and Potassium compared to the control treatment.

3.6. Effect of Zeolite Application on Irrigation Water Consumptive Use

Both treatments (irrigation without zeolite and Irrigation with zeolite) consumed equivalent volumes of irrigation water during the first three months following plantation (December 2024 – February 2025), when soil moisture depletion was relatively slow under cool winter temperatures. Divergence in water demand emerged from March 2025 onwards as temperatures increased and evapotranspiration intensified. By the end of Year 1, zeolite-amended plots required only 38 irrigation events compared with 55 events in the non-amended saline-irrigation treatment, a 31% reduction (Table 6). Total water consumptive use was 210 m³, versus 420 m³, representing a 50% reduction in total water applied.

This reduction is attributed to zeolite's capacity to absorb water equivalent to approximately 65% of its dry weight within its porous internal structure, releasing it progressively to the root zone as soil matric potential decreases (De Smedt et al., 2017; Kennedy, 2020). The result is a prolonged period of adequate plant-available water between irrigation events, effectively decoupling irrigation frequency from the high evaporative demand characteristic of the hyper-arid summer season. These findings corroborate previous reports of 30–50% reductions in irrigation water use following zeolite amendment in arid and semi-arid systems (Hazrati et al., 2022; Cataldo et al., 2024).

3.7. Seedling Survival Under Saline Irrigation

Seedling survival differed markedly between the two species at the end of Year 1 . Prosopis juliflora achieved an overall survival rate of 80% (24 of 30 seedlings), while Tamarix articulata recorded only 20% survival (6 of 30 seedlings). Mortality in T. articulata was concentrated during June–September, coinciding with an increase in irrigation EC from 8.5 to 21.9 dS/m. In contrast, P. juliflora seedlings maintained visible turgidity and shoot extension even during the September EC peak, consistent with its documented mechanisms of osmotic adjustment via compatible solute accumulation and selective ion exclusion at the endodermis (He et al., 2023; Ondrasek et al., 2022). Zeolite amendment provided a modest but observable improvement in establishment conditions. The reduction in rhizosphere EC (from 16.3–21.6 dS/m under saline-only to 15.0–15.6 dS/m under zeolite treatment) and the improvement in plant-available water may have contributed to extended seedling survival, particularly in the early establishment phase (De Sousa et al., 2023; Negahban et al., 2014). Notably, the Na⁺ adsorption function of zeolite (substituting Na⁺ with Ca²⁺ at exchange sites) may have directly reduced ionic toxicity at the root surface by lowering the sodium adsorption ratio in the rhizosphere (Bybordi, 2016; Rahimi et al., 2021). The salinity stress in this study was primarily governed by NaCl, which exerts greater cellular damage per unit EC than SO₄²⁻- or HCO₃⁻-dominated salinity, further underscoring the physiological challenge faced by both species and the practical value of even modest ionic buffering.

4. Discussion

4.1. Zeolite as a Soil Amendment in Saline Dryland Environments

The comprehensive improvement in soil physicochemical properties following zeolite addition observed in this study aligns with and extends the existing literature. The simultaneous enhancement of SMC, CEC, organic matter, and available nutrients, combined with reductions in BD and pH, represents a holistic amelioration of soil quality that no single conventional amendment (gypsum, compost, biochar alone) is known to achieve to the same degree in saline arid soils (Ghorbani et al., 2022; Mondal et al., 2021). The high Si/Al ratio and internal pore architecture of the synthetic clinoptilolite used here likely contributed to both its water retention and ion-exchange efficacy, consistent with the characterization of zeolites as 'water moderators' and slow-release cation reservoirs (Cataldo et al., 2024; Comegna et al., 2023).

A particularly notable finding is the magnitude of the pH reduction (Δ ≈ 1.1 units), which shifts soil chemistry from strongly alkaline (pH 8.3–8.4), a condition that severely limits phosphorus availability and micronutrient solubility, toward a near-neutral range (pH 7.1–7.4) where nutrient bioavailability is substantially improved. This effect is counterintuitive, given that zeolite itself is mildly alkaline, and its mechanism warrants further investigation. We attribute it primarily to the displacement of exchangeable Na⁺ by Ca²⁺ (whose hydrolysis is less alkaline-generating than Na⁺), combined with elevated microbial CO₂ production driven by improved moisture and nutrient conditions (Sindesi et al., 2023b; Aainaa et al., 2018). If confirmed across soil types, this pH-buffering function would add significant value to zeolite's agronomic profile in alkaline arid soils.

The 50% reduction in total irrigation water use achieved in this study is among the largest reported in field settings and carries immediate practical significance for the water-limited context of southern Iraq. Prior greenhouse studies have documented water savings of 15–40% with zeolite application (Hazrati et al., 2017, 2022), but field conditions typically attenuate these effects due to heterogeneous water distribution, macropore flow, and higher evaporative demand. The larger-than-expected saving observed here may reflect the particularly extreme evaporative demand of the study environment (mean annual temperature 28°C; summer maxima > 50°C), under which the zeolite's buffering capacity provided disproportionate benefit relative to temperate contexts.

4.2. Species Salinity Tolerance and Implications for Revegetation

The fourfold difference in first-year survival between P. juliflora (80%) and T. articulata (20%) under identical irrigation and amendment regimes is the study's most operationally significant finding. Prosopis juliflora is a nitrogen-fixing leguminous tree native to Central America but widely naturalized across the semi-arid tropics, where its tolerance to salinity, drought, and heat has been well-documented at a physiological level (He et al., 2023). Its ability to maintain turgor under the EC peak of 21.9 dS/m (equivalent to approximately 55% seawater salinity) through proline accumulation, selective K⁺/Na⁺ discrimination, and leaf abscission to reduce transpirational salt load is consistent with published halophyte physiology (Ondrasek et al., 2022). In contrast, T. articulata, while classified as a salt-secreting phreatophyte with leaf glands capable of excreting Na⁺ and Cl⁻, appears to reach its physiological limit when irrigation EC sustains above 8–10 dS/m through the growing season, consistent with its noted sensitivity to combined osmotic and ionic stress under intense summer conditions (He et al., 2023).

These results carry direct implications for revegetation planning in the southern Iraqi sand and dust storm mitigation programme. Based on current findings, P. juliflora should be prioritized as the primary species for planting in areas where drainage water with EC ≥ 8 dS/m is the principal irrigation source. T. articulata may remain appropriate in areas with access to fresher water or where EC reliably remains below 6 dS/m seasonally. Both species would benefit from zeolite amendment to improve establishment conditions, reduce irrigation demand, and buffer short-term salt surges during critical seedling establishment windows.

4.3. Limitations and Future Research Directions

Several limitations of this study must be acknowledged. First, the experiment comprised two sites with contrasting baseline soil properties (loam vs. silt loam) and lacked full plot-level replication within each soil type. While the observed soil property contrasts are internally consistent and statistically significant, causal attribution is strengthened by the pre–post comparison design and the consistency with mechanistic expectations. Future studies should employ a randomized complete block design with a minimum of three replicate plots per treatment to provide unambiguous treatment effects and enable site × treatment interaction analysis. Second, the zeolite application rate was fixed at 250 g seedling⁻¹; dose–response experiments are needed to identify optimal and economically viable application rates for tree establishment in this setting. Third, this study covers only Year 1; multi-year monitoring is essential to assess the persistence of zeolite effects on soil CEC and water retention, the trajectory of soil salt accumulation with continued drainage-water reuse, and the long-term survival and growth performance of established trees. Fourth, no plant physiological measurements (leaf area, biomass, chlorophyll fluorescence, proline content) were recorded, limiting mechanistic interpretation of the difference in species survival. Future work should incorporate these measurements to elucidate salt tolerance pathways and identify early stress biomarkers for field monitoring applications.

5. Conclusions

This study provides first-year field evidence that synthetic zeolite amendment (250 g seedling⁻¹) substantially improves the soil environment and irrigation efficiency for halophytic tree establishment in a hyper-arid Mesopotamian setting irrigated with saline agricultural drainage water. The principal conclusions are as follows:

1. Zeolite amendment significantly improved all monitored soil properties relative to the saline-irrigation-only control, including soil moisture content (+64–129%), cation exchange capacity (+29%), organic matter (+125–367%), total nitrogen (+30%), and available potassium (+15%). Bulk density declined, and pH shifted from strongly to moderately alkaline, enhancing nutrient availability.
2. Total irrigation water consumptive use was reduced by 50% (from 420 m³ to 210 m³) and the number of irrigation events by 31% under zeolite treatment, demonstrating substantial water conservation potential directly relevant to water-scarce dryland settings.
3. Zeolite amendment partially buffers soil salt accumulation, reducing post-season EC by approximately 4–7 dS/m relative to saline-only irrigation through Na⁺ adsorption and Ca²⁺/Mg²⁺ exchange, thereby mitigating ionic toxicity risk in the root zone.
4. Prosopis juliflora achieved 80% first-year survival compared with only 20% for Tamarix articulata under a seasonal salinity regime peaking at 21.9 dS/m. This finding supports the prioritisation of P. juliflora in revegetation programmes where saline drainage water is the sole irrigation source across the Middle East and analogous dryland regions.
5. Zeolite amendment is recommended as a low-cost, sustainable soil management strategy for improving the establishment of salt-tolerant tree species in saline arid soils, with co-benefits spanning water conservation, soil fertility restoration, and long-term carbon sequestration.

Acknowledgements

The authors gratefully acknowledge the Kuwait Fund for Arab Economic Development (KFAED) for financial support of this work through the project 'Improved Resilience against Transboundary Sand and Dust Storms in Kuwait and Southern Iraq.' The authors also thank the Natural Resources Limited Company for Agricultural Materials Trading and Manufacturing, Baghdad, Iraq ,for supplying the amendment material, and the field teams at Altuba district for logistical support during sampling campaigns.

Conflicts of Interest

The authors declare no conflicts of interest.

Funding

This research was supported by the Kuwait Fund for Arab Economic Development (KFAED).

Data Availability Statement

All data supporting the findings of this study are available from the corresponding author upon reasonable request.