Journal of Water and Soil Science

Effects of Different Fertilization Systems on Nitrogen Mineralization and Dry Matter Yield in Sorghum Cultivation in Sandy Loam Soil

Sina Fallah

This study evaluated the impact of four fertilization systems—no fertilizer, urea-based chemical fertilizer, cow manure, and combined urea and cow manure—on nitrogen mineralization and dry matter yield in sorghum cultivated on sandy loam soil with low fertility. Nitrogen mineralization potential (N₀) was assessed using a first-order kinetic model across various fertilizer treatments. Results indicated that urea-based treatments exhibited superior nitrogen mineralization potential compared to cow manure and combined treatments, with N₀ values ranging from 13.46 to 17.89 mg N/kg soil. Combined fertilization (urea + cow manure) consistently produced higher N₀k values, suggesting enhanced nitrogen availability and mineralization rates. Correspondence between nitrogen mineralization peaks and critical sorghum growth stages was observed, particularly during vegetative and reproductive phases. The highest dry matter yield was achieved with 240 kg N/ha from combined fertilizer, although 160 kg N/ha from the same source yielded comparably. These findings highlight the synergistic benefits of integrating organic and inorganic fertilizers to optimize nitrogen dynamics and crop productivity in low-fertility soils.

Enhancing the Efficiency of Magnetic Biochar Produced from Sugarcane Bagasse for Sodium Ion Removal from Agricultural Wastewater under a Magnetic Field

Elham Ghanbari-Adivi

Conventional methods for desalination of water and wastewater are usually not economically viable for providing the water required for agricultural production due to high energy consumption and equipment costs. This study aimed to evaluate the efficiency of magnetic nanobiochar produced from sugarcane bagasse to remove sodium ions from agricultural wastewater under the influence of a magnetic field. Non-nanoactive, nanoactive, and magnetic nanoactive adsorbents were produced using a pyrolysis process in an electric furnace at 600 °C, chemical activation with potassium hydroxide, and magnetization with a combination of hexahydrate ferric chloride and heptahydrate ferric sulfate. The results showed that the highest removal rates of chloride ions (44.6%) and sodium ions (58.3%) were obtained in the magnetically activated nano-biochar under the influence of a magnetic field of 0.5 Tesla, for an activator-to-biochar ratio of 3, a microwave power of 400 W, and an activation time of 10 minutes. Surface analyses including FT-IR spectroscopy and scanning electron microscopy (SEM) confirmed that the hydroxyl, carboxyl, and carbonyl functional groups on the surface of the adsorbent play a key role in the adsorption of sodium and chloride ions. It was also observed that the application of a magnetic field improved the orientation of the ions towards the adsorbent and weakened the hydrogen bonds in water, which led to an increase in the efficiency of the adsorption process. This study shows that magnetic nano-biochar, under a magnetic field, could be an economical and sustainable solution for reducing the salinity of agricultural wastewater.

Optimum Dose Identification of Organic and Inorganic Coagulants for Stone Quarrying Industries' Wastewater Treatment

Nourollah Mirghaffari

The application of coagulation processes for the treatment of stone quarrying wastewater has increased considerably in recent years. However, limited information is available regarding the appropriate coagulant type, optimum dosage, and pollutant removal efficiency. This study aimed to evaluate the performance of several organic and inorganic coagulants, including polyaluminum chloride (PAC), aluminum sulfate (alum), ferric chloride, zeolite, anionic polyacrylamide (APAM), and cationic polyacrylamide (CPAM), for the treatment of wastewater generated from different stone-processing industries (granite, marble, and travertine) located in Mahmoudabad Industrial Town, Isfahan, Iran. In this experimental study, the effects of coagulant dosage and mixing conditions on the treatment of four types of raw wastewater were investigated using the Response Surface Methodology (RSM). The results indicated that the optimum dosages of zeolite, ferric chloride, and PAC were 200 mg/L, while the optimum dosage of aluminum sulfate was 100 mg/L. For both anionic and cationic polyacrylamide, the optimum dosage was 0.5 mg/L. APAM, CPAM, and PAC exhibited the highest treatment performance among the tested coagulants, respectively. Zeolite showed the lowest removal efficiency (16.5%) for white travertine wastewater, whereas APAM achieved the highest removal efficiency (98.1%) for marble wastewater. Furthermore, analysis of the operational parameters demonstrated that mixing speed and coagulant dosage had the greatest influence on turbidity removal, whereas mixing time showed a comparatively lower effect. Overall, polymer-based coagulants, particularly APAM and CPAM, proved to be highly effective for the treatment of stone-processing wastewater

Growth and Yield of Rice Ratoon Crop (Oryza sativa L.) in Hashemi Cultivar in Response to Nitrogen and Phosphorus Fertilization in Clay Lom Soil Mazandaran

Mohammad Mohammadian

A field experiment was conducted using a factorial in a randomized complete block design to evaluate the growth and yield of rice (Oryza sativa L.) cv. Hashemi in response to nitrogen (N) and phosphorus (P) fertilization. The first factor comprised four N levels (0, 46, 69, and 92 kg N ha⁻¹), and the second factor comprised three P₂O₅ levels (0, 23, and 46 kg P₂O₅ ha⁻¹), with three replications conducted over two cropping years. At the end of the growing season, growth indices, yield, and yield components of rice were measured. The results indicated that the main effects of N and P fertilization on several traits (aboveground dry matter, grain yield, and straw yield) were significant at the 1% probability level. The N × P interaction for grain yield and the main effect of year were significant for most traits at the 5% level. The highest grain yield (935.2 kg ha⁻¹) and straw yield (1455 kg ha⁻¹) occurred with 92 kg N ha⁻¹ and 46 kg P₂O₅ ha⁻¹, representing increases of 115% and 120%, respectively, relative to the control (no N or P applied). This treatment is recommended for rice production under ratoon cultivation in areas with similar climatic and soil conditions

The Impact of Groundwater-Level Changes on Land Subsidence in the Isfahan–Borkhar Aquifer

Arezoo Vahabi

This study evaluated groundwater-level variations in the Isfahan-Borkhar aquifer and examined their relationship to land subsidence. Representative hydrographs, groundwater-level maps, depth-distribution maps for the wettest and driest months of the study period, and a 20-year groundwater-level variation map were prepared and compared with the land subsidence map within the aquifer area. The results indicated that subsidence zones were mainly located in areas experiencing considerable groundwater-level decline. The occurrence of critical subsidence zones in regions with a high density of pumping wells and agricultural lands further confirmed this relationship. In addition, the alluvial-thickness map of the study area was prepared and compared with the land subsidence map to investigate the relationship between the spatial distribution of subsidence zones and alluvial thickness. The findings indicated that land subsidence is associated not only with groundwater-level decline but also with other factors, including alluvial thickness and soil texture. In other words, even under substantial groundwater-level decline, significant land subsidence is unlikely where alluvial thickness and the proportion of compressible fine-grained sediments are low.

Evaluation of the Uniformity of the Center Pivot Irrigation System and its Effect on Canola Yield, Soil Nitrate and Salinity

mohammad mahdi matinzadeh

In many Iranian agricultural farms, center-pivot sprinkler irrigation is widely used as a modern irrigation method. However, improper design, installation, or operation of these systems can reduce their actual irrigation efficiency. Consequently, non-uniform water distribution along the lateral may occur, resulting in localized waterlogging or runoff. These conditions can adversely affect plant growth and alter nitrate distribution and salinity levels in the soil. Two existing center pivot irrigation systems were evaluated at the farm of Qiam Agricultural and Industrial Company in Isfahan. In this evaluation, the average indices of the Christian-Sen uniformity coefficient CU (C), the distribution uniformity coefficient DU, the Hayman and Hein uniformity coefficient CU (H), the potential efficiency of application in the lower quadrant PELQ, and the actual efficiency of application in the lower quadrant AELQ for the two irrigation machines were calculated to be 67%, 57%, 65%, 45%, and 54%, respectively. Comparison of the results with the acceptable ranges for these indices showed that the two systems did not achieve acceptable irrigation efficiency. The results of the study also showed that the volume of water discharged from the different spans varied, with the highest and lowest volumes of discharged water observed in the first and last spans, respectively. Therefore, due to the non-uniform distribution of water across the spans in the studied center-pivot irrigation system, soil samples were collected from beneath different spans to investigate residual soil nitrate concentrations, the salinity of the saturated soil extract, and rapeseed yield. A completely randomized block design was used to compare their means. The results showed that the first span with higher water intake had the highest canola dry weight (1.19 kg/m2), the lowest saturated soil extract salinity (1.67 dS/m), and the lowest residual nitrate in the soil (4.93 mg/kg). The last span with lower water intake had the lowest canola dry weight (0.44 kg/m2), the highest saturated soil extract salinity (3.33 dS/m), and the lowest residual nitrate in the soil (2.203 mg/kg). There was a significant difference at the 1% level between the parameters in different spans. Therefore, it is recommended to use accurate, real-time management tools suited to the crop and climatic conditions of the region to achieve more uniform crop performance across all spans of the center-pivot irrigation system.

Land-Use and Land-Cover Change detection in the Sistan Region Following the Operation of the KamalKhan Dam on the Hirmand River

Saeideh Maleki

The Helmand River is the main source of water for the Sistan Plain and underpins the provision of key ecosystem services, including water supply, agricultural production, forage provision, soil protection, and wildlife habitat. The operation of the Kamal Khan Dam and the diversion of river flow toward Goud-e Zereh have reduced downstream water availability and accelerated land degradation in Sistan. This study aimed to assess land-use and land-cover changes associated with Helmand River water availability before and after the operation of the dam. Land-use/land-cover maps for 2019, 2020, 2024, 2025, and 2026 were produced using Landsat imagery, supervised classification, and the Random Forest algorithm, and their accuracy was evaluated using field-based reference samples. The results showed that, after dam operation, the Hamoun-e Hirmand water body completely dried up, whereas the water-covered area around Kamal Khan Dam and in the Goud-e Zereh region increased from 3,039 ha in 2019 to 62,794 ha in 2026. In the Sistan Plain, agricultural land reached its maximum extent of 69,025 ha in 2020 but declined to 5,776 ha in 2025. In addition, the area of saline lands in the Sistan Plain and Hamoun increased from a minimum of 110,414 ha in 2020 to a maximum of 274,708 ha in 2026. These changes were accompanied by a reduction in rangelands, an expansion of barren lands, increased soil salinity, and greater soil susceptibility to wind erosion. The findings indicate that the diversion of water toward Goud-e Zereh, together with associated declines in agricultural land, rangelands, and soil moisture and the expansion of saline and barren lands, has weakened the ecosystem services provided by the Helmand River.

Estimation of Rainfall Erosivity in Iran

ُSeyed Abolfazl Masoodian

Rainfall erosivity is a key factor in soil erosion models. Although Iran’s climate is predominantly hot and dry, the occurrence of intense and heavy rainfall events, although infrequent, can cause significant damage to soil resources. In the Universal Soil Loss Equation, rainfall erosivity is calculated based on rainfall intensity. In this study, 45 years of hourly rainfall data from the ERA5 reanalysis dataset were used to estimate rainfall erosivity across Iran. The results revealed that the spatial distribution of rainfall events in Iran is highly heterogeneous. Central Iran, with fewer than 20 rainfall events per year, and the Caspian Sea coast, with nearly 450 events per year, represent two contrasting rainfall regimes. Both the Caspian coast and the Zagros highlands receive slightly less than 10 mm of rainfall per event, while the mean duration of rainfall events in these regions is approximately 10 hours. On the Caspian coast, moisture originating from the Caspian Sea, and over the Zagros Mountains, moisture originating from the Arabian Sea, contribute to the observed rainfall duration and amount per event. Rainfall event intensity in the western Zagros and along the entire southern coast of Iran is considerably higher than in other parts of the country. The transport of moisture from the Arabian Sea into Iran contributes to the high intensity of rainfall events in these regions. Rainfall erosivity is very low across most parts of Iran; however, the Zagros Mountains, the Caspian coast, and some mountainous areas exhibit relatively high levels of erosivity. The mean annual rainfall erosivity over Iran is approximately 80 MJ.mm.ha^-1.h^-1.y^-1.

Analysis of Farmers’ Attitudes toward Groundwater Over-Abstraction and Its Socioeconomic Consequences in the Siminehroud Catchment

Marzban Faramarzi

Excessive groundwater abstraction is a major environmental and economic challenge in Iran’s arid and semi-arid regions. This study examined farmers’ perceptions of groundwater over-abstraction and its perceived socioeconomic consequences in the Siminehroud catchment. Data from 373 questionnaires were analyzed using descriptive statistics, Mann–Whitney U tests, and chi-square tests. Effect sizes were reported, and p-values were adjusted using the Benjamini–Hochberg procedure. Overall, 41.8% of respondents believed that groundwater over-abstraction was occurring in their locality. Respondents with this perception were younger (median 48.5 versus 53 years; p<0.001), and the proportion with this perception was lower among users of piped water conveyance than among users of traditional canals (24.2% versus 45.6%; p=0.001). Both associations remained significant after false-discovery-rate adjustment. The most frequently perceived consequences of groundwater-level decline were declining farm income, loss of irrigated land, changes in cropping patterns, and increased migration. The findings indicate that groundwater management in Siminehroud should incorporate aquifer monitoring, improved water conveyance, and social interventions tailored to users’ characteristics.

Site Selection and Land Capability Evaluation for Pistachio Cultivation Development in Sistan and Baluchestan Province Using GIS and AHP

Alireza Salehi

This research was conducted with the aim of site selection and land capability evaluation for the development of pistachio cultivation in Sistan and Baluchestan province by integrating Geographic Information Systems (GIS), the Analytical Hierarchy Process (AHP), and remote sensing data (Landsat 8 satellite imagery within the Google Earth Engine platform). Eight criteria, including distance from water canals, roads, and population centers, land use, slope, elevation, slope aspect, and soil characteristics (salinity, texture, and pH), were weighted based on the opinions of 15 experts (inconsistency ratio = 0.03). The highest weights were assigned to distance from water canals (0.32), soil characteristics (0.25), and distance from roads (0.14). Information layers with a spatial resolution of 30 m were prepared in the GIS environment and integrated using the weighted overlay method. The final map showed that 13.8 percent of the province is in the highly suitable class, 23.0 percent in the moderately suitable class, 33.5 percent in the marginally suitable class, 27.5 percent in the unsuitable class, and 2.2 percent has absolute limitations. The findings indicated that 36.8 percent of the province has significant potential for the development of pistachio cultivation; however, the main limitation is access to water resources. 65.5 percent of the province is located in the unsuitable category in terms of distance from water canals. Therefore, the sustainable development of pistachio cultivation in the province requires precise planning with a focus on suitable areas and the sustainable management of water resources. The novelty of this research lies in applying Boolean masks to eliminate ecological errors and using cloud computing (GEE) for the temporal consistency of data. Furthermore, comparative analysis revealed that crop development in some areas (such as Zahedan) relies more on groundwater extraction than on inherent land potential; the model classifies these areas as "unsuitable," providing a preventive warning regarding long-term sustainability

Hydro-Economic Assessment of Managed Aquifer Recharge Using Treated Wastewater: A Case Study of the Qotbabad Plain

Siamak Boudaghpour

Managed Aquifer Recharge (MAR) using treated wastewater is a viable strategy for water-resource sustainability in arid regions; however, the simultaneous assessment of its hydrogeological and economic aspects remains challenging. The objective of this study was to hydro-economically evaluate the implementation of an MAR project in the Qotb-Abad Plain by integrating numerical modeling and cost-benefit analysis (CBA). The quantitative and qualitative responses of the aquifer were simulated using the MODFLOW and MT3DMS models to estimate changes in groundwater levels, nitrate concentrations, and total dissolved solids (TDS). Economic benefits, including pumping energy savings, the value of stored water, and improvements in water quality, were evaluated alongside capital and operational costs under lower- and upper-bound scenarios. Subsequently, economic indicators, including net present value (NPV), benefit-cost ratio (BCR), internal rate of return (IRR), and payback period, were calculated. The results indicated that implementing MAR with an annual treated wastewater volume of 1.898 million m³ resulted in an approximately 4.5 m rise in groundwater level, accompanied by reductions in TDS from 1859 to 1752 mg/L and in nitrate concentration from 22.2 to 15.4 mg/L by the end of the five-year simulation period. Under the upper-bound scenario, the NPV, BCR, and payback period were 43.7 billion Rials, 1.36, and 3.23 years, respectively. In contrast, the lower-bound scenario was not economically justified, as its BCR was less than 1. Overall, integrating numerical modeling with cost-benefit analysis provides a comprehensive framework for supporting groundwater-management decision-making.

Biological Index of Tree Leaves (Albizia lebbeck, Prosopis cineraria, and Eucalyptus globulus) in Ahvaz City for Nickel Monitoring

Maryam Mohammadi Rouzbahani

Nickel (Ni) is an essential element for living organisms and plays important biological roles in plants; however, its accumulation at high concentrations can cause toxicity and adverse effects. This study aimed to evaluate nickel accumulation using the leaves of Albizia lebbeck, Prosopis cineraria, and Eucalyptus globulus as biological indicators in Ahvaz City during the summer of 2025. A total of 126 leaf samples and 63 soil samples were collected from seven stations across Ahvaz City. Chemical digestion of the leaf and soil samples was performed using the Johnson and EPA 3050 methods, respectively. Nickel concentrations were determined using atomic absorption spectrometry. Significant differences were observed in Ni concentrations among the leaves of Albizia lebbeck, Prosopis cineraria, and Eucalyptus globulus (P < 0.05), whereas no significant difference was observed in Ni concentrations among the soil samples (P > 0.05). The highest and lowest Ni concentrations in the unwashed and washed leaves of Albizia lebbeck were 36.2 and 10.3 mg kg⁻¹, respectively. The highest and lowest Ni concentrations in the soil samples collected from the tree rhizospheres were 57.36 and 44.1 mg kg⁻¹, respectively. The highest Ni transfer factor was observed in Albizia lebbeck leaves (0.446), whereas the lowest was observed in Eucalyptus globulus leaves (0.203). The Ni transfer factors for the leaves of Albizia lebbeck, Prosopis cineraria, and Eucalyptus globulus, together with the linear regression analysis of Ni concentrations in washed and unwashed leaves, indicate that atmospheric deposition may be an important source of Ni accumulation in the leaves. In contrast, the contribution of soil-derived Ni to leaf accumulation appears to be relatively low.