Water and Soil Science
Year:2024 | Volume:34 | Issue:2|Papers Count:15

AbstractBackground and ObjectivesSpillway as a hydraulic structure is used to controlled release of water from a dam or levee downstream. One of the types of spillway used in dams is vertical shaft spillway or the same as morning glory spillway (MGS). Shaft spillways are used where there is not enough space for conventional spillways in the dam reservoirs,. The morning glory spillway (MGS) is formed by a crest, a conical transition, a vertical shaft, a bend, and an outlet tunnel. Swirling flow is a fundamental problem encountered in hydraulic engineering, resulting in air-entraining vortex at pipe intakes and shaft spillways. Forming at hydraulic intakes, these vortices reduce intake efficiency and can lead to unstable operation and vibration in downstream hydraulic machinery. One of the methods to increase the flow rate and reduce the occurrence of vortex currents in the spillway is to modify the inlet shape of the spillways. In recent years, spillways with daisy, piano key and zigzag inlets have been proposed known as spiral spillways. A number of researchers have studied vertical shafts with different inlets and defined their own characteristics. A review of the results of previous research shows that the common goal in the study of vertical shaft spillways is to pass the flood flows with the highest possible discharge and the lowest water level and reducing the destructive effects of vortex currents. In the previous researches, issues such as the effect of the inlet type of vertical shaft spillway and geometric parameters of the structure on the discharge coefficient and conditions of vortex occurrence and hydraulic of vertical shaft spillway flows have been studied. In this research new shapes of vertical shaft inlet in form of Bow-tied and Spindle spillways were introduced and discharge coefficient of these spillways was investigated using a series of experiments and the results compared with common shapes of vertical shaft inlet in form of the Daisy, Morning Glory, Square, Hexagonal and Octagonal spillways.MethodologyIn this research, the effect of different input shapes on the flow hydraulics of vertical shaft spillway was studied. For this propose, models of Bow tie spillway with middle and without arches, Spindle, Daisy, Hexagonal, Octagonal and Square with the same total length were used and discharge coefficient of the models were calculated and the results were compared with a Morning Glory spillway. The experiments of this research were performed in a metal cube tank with 1.5 m length, 1 m height and 1 m width with transparent Plexiglas side walls in the hydraulic laboratory of Department of Water Engineering at Zanjan University. In this research, by preparing eight models of the studied spillways with a total length of 60 cm and considering the hydraulic conditions (H/D), 63 experiments were run to investigate the effect of the geometric shape of the spillway on the discharge coefficient.FindingsThe results showed that the Bow-tie without middle arch model cause to uniform the flow regime and has a significant effect on reducing water head and increase the discharge through the shaft, so that Bow-tie without arch model has a higher discharge coefficient than other models. It has better hydraulic performance (10.4%) compared to Morning Glory spillway and also has higher economic benefits (30.88%). Comparison of the Spindle, Daisy, Square, Hexagonal and Octagonal models with the Morning Glory spillway shows that in low and high discharge, the Daisy and square models have better performance, respectively (3.45 and 5.1%, respectively). Also, the Bow-tie with middle arch model did not have a significant effect on the discharge coefficient and its hydraulic performance decreased in compared to the Morning Glory spillway (-2.3%), which could be due to low internal surface and interference of downstream flows.ConclusionComparison of the hydraulic performance of Bow-tie and Spindle models with the other shapes shows that the model of Bow-tie without arch has the highest hydraulic performance and a better economic advantage. In the construction of reservoir dams, especially earthen dams, the major part of the executive cost is related to the implementation of concrete structures of emergency spillway. In this situation, by choosing Bow-tied spillway with optimal geometry, a suitable economic savings can be achieved along with improving the hydraulic conditions of the flow.

Background and Objectives: Biofertilizers play major role in sustainable agriculture. Biofertilizers are inoculants containing useful microorganisms which are used in solid, liquid and/or encapsulated formulations. Different materials can be used as liquid carriers. Increasing inoculant longevity by using different materials is the main purpose in production of liquid inocula. These additives are carbon-based and reduce environmental stresses. In this study the effectiveness of liquid inocula of Enterobacter cloacae S16-3 on oil content, fatty acids and nutrient uptake of rapeseed in a sterile sandy loam soil were evaluated. Nine liquid inocula of S16-3 (F1-F9) were prepared using different amounts of materials including glycerol, polyethylene glycol (PEG), trehalose, carboxymethylcellulose (CMC), Arabic gum (AG), polyvinylpyrrolidone (PVP), glucose and starch, in different combinations. Then, the effect of liquid inocula on growth of rapeseed (Brassica napus L.) cultivar hyola 308 was investigated. Methodology: The experiment was carried out in greenhouse condition based on completely randomized design (CRD) with three replications. The factors were including 9 liquid inocula (F1-F9), in all these treatments, 70% of NPK was added to the soil in each pot, since we assumed that S16-3 is able to supply only 30% of these elements, one control treatment without adding any bacteria and fertilizer (negative control), and two positive controls (using NPK equal to 70% and 100% of fertilizer recommendation). Germinated seedlings of rapeseed were planted and inoculated with inocula in each pot. Except for NPK elements, other micronutrients were provided based on soil test; however, in the case of nitrogen, phosphorus and potassium elements that were the main objective of this experiment, no chemical fertilizer and bacteria were used in negative control treatment. In positive control (100NPK), based on the soil test and previous experiments, 100% of the recommended amount of fertilizer, equivalent (56.5 mg N/kg soil, from Urea source), (13 mg P/kg soil, from triple superphosphate source) and (31.3 mg K/kg soil, from potassium sulfate source) were used, moreover, for other positive control treatment (70NPK), 70% of the above values in pot culture were added to the pots. During the growth period, irrigation was performed with sterile water and the moisture content of the pots was maintained by weighing in a moisture range (0.7 - 0.8 FC). In pot culture, characteristics such as dry weight of roots, shoots and seed, seed oil percentage and fatty acids, uptake of nitrogen, phosphorus, potassium, iron, zinc, manganese and calcium in the root and shoot were measured. Findings: The results obtained from the greenhouse experiments showed that the dry weight of roots, shoots and seed, seed oil percentage and fatty acids, uptake of nitrogen, phosphorus, potassium, iron, zinc, manganese and calcium in the root and shoot of rapeseed (Brassica napus L.) cultivar hyola 308 were significantly influenced by the presence of E. cloacae bacteria (in the form of nine inocula) and 100NPK and 70NPK treatments. The highest percentage of seed oil (47.02%) and the highest amount of oleic acid (53.1%) was obtained by F9 (glycerol, glucose, AG, PEG) treatment, and oil quality was affected by bacterial inoculation. the highest amount of saturated fatty acids, such as stearic acid (4.5%) and palmitic acid (5.6%) was measured in without inoculation treatment (negative control). Nutrition analysis in dry tissue of plant showed that 100NPK treatment had the highest N, K, Fe, Zn and Ca uptake in the plant, and among liquid inocula treatments (F1-F9), the highest uptake of these elements belonged to the F5 (AG, starch, PEG). The highest amount of total P in F1 treatment (glycerol, trehalose, CMC) and F4 (trehalose, AG, PEG) and highest Mn absorbed in the plant were obtained in F5 treatment.Conclusion: In most measured indices, the effects of liquid inocula had higher performance than without inoculation treatment (negative control). From the nutritional point of view, F5 (AG, starch, PEG) liquid inoculant were better than the other inocula. F9 treatment had a significant effect on quantitative and qualitative characteristics of rapeseed oil. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Background and Objective: Water is the most important and limiting production factor in agriculture. The rapid decline of groundwater table is threatening sustainable irrigation agricultural development. Considering the limitation of ground water resources and the necessity of optimal use of surface water, the reform of the Irrigation systems is a necessity. Iran is located in one of the driest regions of the world. Based on this, one of the major challenges in providing food for the growing population is the issue of water and proper management of water resources. With the increasing shortage of irrigation water, new irrigation methods for optimal use of water will be more important in the future. Another way to increase water productivity is to adopt deficit irrigation strategies. Deficit irrigation is defined as the use of water less than the plant's water requirement, which has been developed in many countries in order to reduce the amount of irrigation water.Methodology: This study compares the effects of different irrigation regimes on seed yield and water productivity of canola with three irrigation mathods of furrow, sprinkler and drip whith foure irrigation treatments included 60, 80, 100, and 120 percent of full irrigation amount. For this purposea field experiments was carried out using a split plot arrangement in randomized block design with three replications inTabriz in 2018-2019 and 2019-2020 grwoing seasons. The soil class of the farm is sandy loam. The amount of effective rainfall in the growing season was 278 mm in the first year and 202 mm in the second year.In each experimental unit of furrow and drip irrigation method, there were 4 rows of planting 8 meters long and in each experimental unit of sprinkler irrigation method there were 6 rows of planting 3 meters long. The distance between planting rows was 50 cm and the distance between plants in each row was 3 to 5 cm, and the seeds were planted at a depth of 1 to 2 cm. Octans autumn hybrid canola seed variety was used for cultivation. Hunter model A12 hidden sprinkler with a spraying radius of 3.7 meters was used for sprinkler irrigation. In this plan, a sprinkler was installed in each corner of the plot, and to prevent interference between the plots, the radius of the sprinkler was adjusted to 90 degrees. For drip irrigation, a strip with an aperture distance of 20 cm and a thickness of 175 microns was used.In this research, the irrigation timing was applied in the furrow method based on the fixed cycle of 10 days for the area and for drip and sprinkler irrigation cycle of 5 days. The amount of irrigation water in each irrigation round was estimated by measuring the volumetric soil moisture before each irrigation round in the full irrigation treatment, and according to the area of each plot and applying the irrigation efficiency, the amount of water used for each method was obtained. The actual evaporation and transpiration of rapeseed was obtained from the water balance equation. At the end of the growing season, the product of each plot was harvested separately and the weight of dry matter, weight of seeds, weight of 1000 seeds, the amount of yield per unit area and other characteristics were measured and recorded, and the parameters related to water consumption efficiency for each plot were was achievedFindings: The obtained results showed that regardless of the amount of irrigation, crop yield and other growth indicators were better in drip irrigation than the other two methods, so that the drip method at the level of 120% had the highest amount of yield, weight of 1000 seeds and plant height. The lowest amount of irrigation water is related to the drip method at the level of 60%, and this method reduced the amount of irrigation water by 49% and 21%, respectively, compared to furrow and sprinkler irrigation at the same level. The highest value of water prodoctivity and irrigation water prodoctivity related to drip irrigation was at the level of 60%. At this level, the drip method increased the efficiency of water prodoctivity by 87% and 25%, respectively, compared to the furrow and sprinkler method. Conclusion: The results of this research showed that the use of modern irrigation methods such as drip and sprinkler instead of the surface methods, in addition to saving the amount of water used, also improves the performance of the product. Also, the application of deficit irrigation techniques in these methods will have less yield loss and increase the water use efficiency compared to traditional methods.

The present study was conducted based on the results of field visits and data collection from different locations of modern distribution networks including tertiary and fourth degree channels as well as the traditional water distribution irrigation network in the cities of Khuzestan province in 2017. The lowest and highest distribution efficiencies were calculated at 46.88 and 99.69% in Baghmalek and Shushtar counties. The average distribution efficiency in all studied channels was 79.75%. The lowest distribution efficiency in teritary channel was 0.60 and the maximum distribution efficiency in fourth degree channel was 99.67%. This was while 36.4% of earthen canals had poor distribution efficiency. In this study, the values of distribution efficiency calculated in different canals showed that the type of ownership of canal is effective in increasing the distribution efficiency. In a way the average distribution efficiency in the canals covered by irrigation and drainage networks as non-personal channels were significantly different from the channels managed by the farmer (personal channels) at the level of 5%. Scientific management performed by irrigation and drainage networks in Khuzestan province caused about 60% of non-personal water distribution channels to have acceptable irrigation efficiency, while the lack of sientific management on personal canals (under Farmer management) including non-volume delivery of water due to mismanagement masurrement structures has caused about 85% of channels under farmer management do not have acceptable distribution efficiency.

Background and Objectives: Synthetic dyes, widely used in the textile industry, are the major water contaminants. Bacterial degradation is an eco-friendly, cost- effective, highly efficient approach. Unfortunately, some of these toxic wastewaters are discharged into the environment without proper treatment, which results in environmental pollution. Today, the available water for use in industrial activities, agriculture, etc. is decreasing. By treating the wastewater of textile factories, the purified water can be returned to the production cycle. Microorganisms such as bacteria, filamentous fungi, yeasts and algae are able to decolorize azo dyes, but so far there has been no complete report on decolorization by facultative thermophilic bacteria. Facultative thermophiles are those that can grow at high temperatures as well as at relatively lower temperatures, e.g., below 50 °C. Methodology: To isolate dye-degrading bacteria, wastewater samples were collected from different parts of a textile wastewater treatment plant located in Kashan, Iran. The different media such as tryptic soy broth (TSB), modified M9 minimal salts medium, was used to enrich the bacteria in textile wastewater. The enriched samples were used for the isolation and purification of textile azo dyes degrading bacteria as a pure culture on TSA and wastewater agar (WA) plates under aerobic conditions. In this study, the strains of facultative thermophile bacteria that can effectively degrade azo dyes were successfully isolated in the M9 media (53°C). The amount of decolorization activity of isolated bacteria was determined by using the modified M9 medium containing 150 mg l-1 using the commonly used dyes Rimazol Black 5, Reactive Red 198, Reactive Blue 21, and Reactive Yellow 15.Optimization of decolorization conditions in selected bacteria was done using Minitab 14 software and Response Surface Methodology (RSM). These experiments were conducted in order to investigate the factors of temperature, salt concentration, inoculation, color concentration, pH, and time at different levels. The identification of the selected SN7 bacterial strain was done through 16S rRNA gene sequence analysis and conventional biochemical tests and was registered in Iran's Industrial Microorganism Collection Center (PTCC).Findings: The conditions for the proliferation and enrichment of dye-degrading bacteria in textile wastewater were provided through the enrichment method using TSB culture medium containing Rimazol Black and modified M9 medium containing Rimazol Black. The 47 dye degrading bacterial strains were isolated by using culture medium containing of Remazol black 12 strains of facultative thermophilic bacteria that degrade dyes in textile waste were obtained by investigating the ability of the isolated bacteria to grow at 53°C. The ability of bacteria to decolorize azo dyes was 22 to 71.5% at 48 ° C for 72 h. Among the isolated bacteria, two strains SN7 and SN10 had the most decolorization and the decolorization rate of each at 48°C after three days of incubation was 71.5% and 70% respectively. The SN7 strain was used to further investigate the dye degradation due to the ability of the SN7 strain to grow well in the medium containing the dye as well as its ability to remove it in a shorter period of time. Analysis of the 16S gene sequence of SN7 strain shows 93.99% similarity with Bacillus paralicheniformis Bac84. Therefore, this strain was named Bacillus paralisniformis SN7 and was registered with PTCC number 1907 in the Culture Collection for Research and Industrial microorganisms of Iran. The strains Bacillus paralicheniformis SN7 was chosen and was used for further characterization. B. paralicheniformis SN7 was capable of degrading reactive dyes such as of Remazol black 5, Reactive Red 198, Reactive Blue 21 and Reactive Yellow 15. The ability of this bacterium to decolorize Remazol Black 5, Reactive Red 198, Reactive Blue 21, and Reactive Yellow 15 was 71.5, 75.6, 72.2, 76.2% respectively. The optimum concentration of dye, pH, and temperature as analyzed by RSM were found to be 50 mg/l, 7, and 45°C, respectively, for decolorization Remazol black (71.5%). Conclusion: Among the isolated bacteria, facultative thermophilic strains were isolated and B. paraliceniformis SN7 has the ability to decompose dyes. Degradation of azo dyes, unlike surface adsorption, is of considerable importance as a desirable method because the dye is completely degraded by microbial enzymes.Some microorganisms can use dye compounds as their source of carbon and energy. Complete biological decolorization has also been observed in anoxic and anaerobic conditions. Under anoxic conditions, decolorization was higher compared to aerobic conditions when the bacteria were cultured under aerobic conditions and then under anoxic conditions. Sequential of two stages under aerobic and anoxic conditions has been proposed for decolorization of azo dye-containing wastewaters. Anoxic conditions do not contain molecular oxygen and may contain nitrate or nitrite.

Background an objectivesIn the past, many studies have been carried out on the hydraulics of sliding valves. In addition to flow control and measurement, this structure is used for energy consumption downstream. This structure plays an important role in controlling and regulating the speed downstream of the structure. The supercritical flow passing through sliding valves has attracted the attention of researchers due to its high energy dissipation. The high velocity of the flow in the downstream of the hydraulic structures is one of the important issues of water engineering and usually causes damages if there is no control in the downstream. The creation of hydraulic jump is associated with the transformation of supercritical to subcritical flow, and as a result, energy consumption occurs. This phenomenon can be seen downstream of structures such as dams, rapids and valves. So far, successive methods have been used to reduce the kinetic energy of the flow passing through the sliding valves, which are discussed below. Among the first researches in this field, the studies of Rajaratnam (1967), Rajaratnam (1968) and Alhamid, (1994) can be mentioned. Daneshfaraz et al. (2022a) investigated the hysteretic behavior of the supercritical flow which occurs with two different flow behaviors under the same hydraulic conditions. The results showed in the primary flow, the amount of these depths indicates the subcritical regime, and in the secondary flow, with the formation of the hysteresis phenomenon in some flow rates, it indicates the supercritical regime. The hysteretic phenomenon has a different effect on the amount of energy consumption depending on the type of flow.MethodologyThe experiments were performed in a laboratory flume 5 m long, 0.30 m wide, and 0.45 m deep. The laboratory channel has a floor and walls made of Plexiglass and is equipped with a point depth gauge with an accuracy of ±1 mm. A 1 cm thick sluice gate is installed one meter away from the beginning of the flume. In all experiments, the gate opening was considered constant and equal to 5 cm. The discharge applied in the present study ranged from 700 to 900 l/min. The effect of the threshold with semi-cylindrical, cylindrical, pyramidal, and rectangular cube geometric shapes and with different widths of 5, 7, 10, 15, and 20 cm was investigated experimentally. In the present paper, the sill was installed in the different position, including under, the tangential state downstream and upstream of sliding valve.FindingsThe energy dissipation of the sluice gate was investigated in the non-sill mode and with increasing discharge. Laboratory studies showed that the increase in flow rate caused an increase in the flow speed and consequently the descent number of the supercritical region. As a result, the depth of flow in section A has decreased and it has caused energy consumption downstream of the sliding valve. Energy consumption by installing sill in different positions showed that all four geometries, including semi-cylindrical, cylindrical, pyramidal and rectangular cubic sill, had the maximum energy loss in the position under the valve. Results showed that for undergate sill, the maximum of energy dissipation is related to pyramidal, semi- cylindrical, cylindrical and rectangular cubic sills, respectively. The increase in the jetting streamlines due to the application of the pyramid sill is evident in the tangential position downstream of the valve. The results showed that placing circular sills, including semi-cylindrical and cylindrical, in the downstream of the sliding valve, cause the uniformity of the flow lines. Therefore, the depth of the flow in the initial section of the hydraulic jump is reduced compared to the polygon sills.Conclusion The results showed that:1. The amount of energy loss increases with the increase in sill width.2. Due to having the slope of the downstream side in the same direction as the flow, the pyramid threshold increases the speed of the flow and therefore causes a decrease in the initial depth of the flow.3. Circular sills including semi-cylindrical, cylindrical and rectangular cube were included, respectively, with the greatest initial depth4. By changing the position of the threshold to the tangent position downstream of the sliding valve, the highest amount of energy loss was assigned to semi-cylindrical, cylindrical, rectangular cube and pyramidal thresholds, respectively.

AbstractBackground and Objectives: The constant need to increase agricultural production, along with more and more frequent drought events in the country, requires a more accurate assessment of irrigation needs and thus a more accurate estimate of actual evapotranspiration. Prediction of water consumption over agricultural areas is important for agricultural water resources planning, management, and regulation. It leads to the establishment of a sustainable water balance, mitigates the impacts of water scarcity, as well as prevents the overusing and wasting of precious water resources. As evapotranspiration is a major consumptive use of irrigation water and rainwater on agricultural lands, improvements of water use efficiency and sustainable water management in agriculture must be based on the accurate estimation of ET. Irrigated agriculture is expected to produce more crops with less water consumption in the future. Therefore, accurate forecasting of water demand along with sustainable management and more efficient methods to meet the growing demand under scarce water resources is necessary. The models used to predict evapotranspiration should be used in different regions with different climates to evaluate their performance. Therefore, in this research, tree models and Hargreaves were used in Yazd and West Azerbaijan provinces, which have different climates, in order to evaluate the performance of the models used.Methodology: In recent years, water management issues have been addressed using models derived from artificial intelligence research. In recent years, water management issues have been addressed using models obtained from multiple types of research. The use of combined models has made significant progress in recent years. combined models are able to perform processing in a short period of time and at the same time with high accuracy. Using these models, the main challenging aspects are represented by the selection of the best possible algorithm, the selection of suitable representative variables and the availability of suitable data sets. Therefore, in this study, the ability of tree models (M5P and RF) with Hargreaves model (Hs) in estimating daily evapotranspiration in Urmia and Yazd stations during the period of 2000-2021. The noteworthy point is that in the combined tree-Hargreaves model, the used tree models were used as input to the Hargreaves model. The combined model has been used for the first time in this research and the use of this model can predict daily evapotranspiration as well as possible.Findings: The results of the model are performed using 5 evaluation criteria of Coefficient of determination, Root mean square error, Nash-Sutcliffe coefficient, and Wilmot’s index of agreement. In all the used models, the best scenario was the model whose input included parameters of minimum temperature, maximum temperature, relative humidity, wind speed, and sunshine hours. Comparison and evaluation of standalone tree models showed that in the Urmia station two models RF-5 and M5P-5 had less error (0.4 and 0.38-mm day-1, respectively) than other standalone models. Similarly, in the Yazd station, RF-5 and M5P-5 models have higher accuracy (0.36 and 0.35 mm day-1(, respectively) than other standalone models. For combined models, the obtained results showed that the fifth scenario of the M5P-Hs model provided the best performance in Urmia and Yazd stations with the lowest error (0.33 and 0.24 mm day-1) respectively. It was also concluded that the fifth scenario of the RF-Hs model in Urmia and Yazd stations had a lower error (0.36 and 0.26 mm day-1) than other models, respectively. Finally, tree models have increased the accuracy of the Hargreaves model in this research.Conclusion: Finally, the RF, M5P, RF-Hs and M5P-Hs models were able to predict daily evapotranspiration values in the shortest time and with the highest accuracy. However, the results showed that the lower the model inputs, the weaker the model prediction. The results of this research showed that the combination of tree models with Hargreaves model is able to predict daily evapotranspiration values with high accuracy compared to individual models. The results of this research showed that the wind speed parameter is one of the most important meteorological parameters needed in estimating daily evapotranspiration, so adding this parameter results in the highest accuracy in all models. Also, due to the important role of wind speed in predicting daily evapotranspiration values and the unavailability of the maximum wind speed parameter in this research, it is recommended to use the maximum wind speed parameter as one of the model inputs for further studies.

Extended abstractBackground and ObjectivesGroundwater quality assessment and related hydrochemical characters are critical for water resources management in the arid and semi-arid regions. Water quality is a function of physico-chemical parameters and strongly influenced by geological formations and human activities. The hydrochemical evolution of groundwater mostly depends on the chemistry of the aquifer materials, water and rock interaction and water residence time. Water quality assessment requires knowledge of mineralogy of the surrounding rocks and identification of relevant chemical reactions. Ions in groundwater may be of natural source, human origin or a combination of both factors. The Lanjanat is the largest Plain in Isfahan Province and is located in the Gavkhouni Basin where the Zayandehroud River is passing. According to the geological classification of the country, Lanjanat Region is located in the Sanandaj-Sirjan structural zone. The hard rocks exposed in the heights surrounding area include Permian rocks, Jurassic sediments (including dark gray shales with interlayers of sandstone, quartzite, limestone, and volcanic), shale, marl, and Cretaceous limestone, conglomerates, and Paleogene sandstones. The Quaternary sediments exposed in the plain have formed an alluvial aquifer over the impermeable Jurassic shales. The main recharge source of the Lanjanat Aquifer is meteoric water, which decreases from west to east and from south to north of the basin. Lanjanat plain is one of the most fertile agricultural centers in Isfahan Province, which in recent years has faced a quantitative and qualitative crisis of water resources due to the increasing population, development of industries and agriculture and also excessive extraction of groundwater. In this research, an attempt has been made to update the information related to the quality of surface and groundwater and to determine the origin and hydrochemical evolution of the groundwater in the plain.MethodologyIn this research, 13 locations of surface and underground water sources, including rivers, springs, Ghanats, agricultural wells, and fields were selected for sampling. The pH, temperature and electrical conductivity of water were measured in fields. Also, total dissolved solids and major ions concentration were determined in the laboratory. After determining the physicochemical characteristics and concentrations of the main ions of the samples, to understand the relationship between the main hydrochemical variables, a Pearson correlation matrix was provided. Besides, the ion ratio diagrams (including sodium vs. chlorine ratio, bicarbonate vs. sodium, calcium vs. sulfate, calcium and magnesium vs. bicarbonate and sulfate, calcium vs. bicarbonate, and bicarbonate vs. magnesium) together with the combination charts, and Piper's diagram were used to determine the origin of ions in water sources.Finding conclusionThe results showed that the minimum and maximum concentrations were respectively observed in the river samples and the deep wells located in the central sector of the plain. The range of water electrical conductivity was between 264 5755 µ/cm in the rice field and 5755 µ/cm in the agricultural well. The total dissolved solids was between 271 mg/liter in the river sample and 3889 mg/liter in the agricultural well. The amount of dissolved solids was increased by moving from the sides towards the central sector of the plain, as well as by increasing the depth of the wells. The water type of the samples varies from calcium bicarbonate near the carbonate formations to calcium sulfate or sodium chloride in the central sector of the plain. The Pearson correlation matrix showed a very strong positive correlation between the total dissolved solids and electrical conductivity of water and a strong inverse correlation between pH and total dissolved solids and electrical conductivity. The concentration of the main anions and cations in the surface and underground waters of the region was mostly affected by natural factors, especially the dissolution of carbonate and evaporative minerals. According to the results of the ion ratio diagrams, the origin of the main ions in the water resources of the region was mostly from the dissolution of geological formations, although human activities were effective in some places. Agricultural activity has caused an increase in concentration of some ions by using fertilizers (such as sodium and sulfate). The present research is only based on the results of a sampling period of 13 surface and underground water sources. In order to better understand the hydrochemistry of the plain, it is suggested to carry out monthly sampling during a water year, and at more points. Also, in addition to the main anions and cations, the concentration of nitrate, phosphate and heavy metals should also be measured and analyzed.

Background and Objectives: Soil and groundwater contamination by petroleum hydrocarbons might cause negative environmental impacts. It may adversely affect soil physical conditions and quality such as hydraulic properties via raising soil water repellency. Soil structure is an important physical characteristic depending on pore size distribution and continuity, and it can affect several soil physical and chemical processes. Soil structure might be affected by physical weathering processes such as wetting/drying and freezing/thawing cycles. It is possible to reproduce the natural soil structure in the laboratory by imposing wetting/drying and freezing/thawing cycles on the repacked soil samples. This would minimize the possible changes in soil structure during core sampling from the field. Few studies have been conducted about the interactive effect of oil contamination, soil texture and structure on soil water repellency and hydraulic properties. The present study aims to investigate the interaction effects of crude oil application, soil texture and weathering-induced structure on soil water repellency and hydraulic properties.Methodology: In this study, the effect of crude oil application and physical weathering on water repellency and hydraulic properties of two soils (sandy loam and clay loam) was studied in a factorial experiment of completely randomized design with three replicates. Soil samples were collected from 025 cm layer of agricultural lands in Chaharmahal-va-Bakhtiari province, central Iran (sandy loam and clay loam soils were located in 32° 43' N 51° 59' E and 32° 29' N 50° 42' E, respectively). The soil was ground and sieved through a 4-mm mesh to exclude the gravel particles and plant residues. Crude oil was solved in the n-hexane and added to soil with the concentrations of 0.5 and 1 %w/w of total petroleum hydrocarbons (TPHs). Besides, a control without crude oil addition was included in the experiment. The treated soils were then poured into stainless cylinders (height and diameter of 5 cm) and packed to natural bulk density of 1.45 and 1.43 g cm-3 for sandy loam and clay loam soils, respectively. Half of the prepared soil samples were tested immediately and named “repacked” treatment and the rest wetted and dried for five months under normal conditions in the greenhouse and was named “physical weathering” treatment. Thus, a total of 36 soil samples were prepared (2 soil types × 3 levels of water repellency × 2 weathering treatments × 3 replicates). Then, water repellency was determined by water drop pentetration time (WDPT) on the treated soil cores. Soil water characteristic curve and saturated hydraulic conductivity (Ks) were measured on the soil cores and modeled by van Genuchten equation. Soil physical quality indicators including field capacity (FC), permanent wilting point (PWP), available water colntent (AWC), macroporosity (Macro-P), mesoporosity (Meso-P), microporosity (Micro-P), and Dexter’s index for soil physical quality (SDexter) were calculated as well.Findings: The results showed that soil hydraulic properties were significantly affected by the experimental treatments. Water retention was greater in the clay loam soil compared to the sandy loam soil. Oil contamination reduced soil water retention at all matric suctions (0 to 15000 cm) due to oil-induced water repellency and soil resistance against wetting (as observed by an increment in WDPT). The effect of oil contamination on water retention was greated in the sandy loam soil than in the clay loam soil due to lower specific surface area of coarse-textured soils. The Ks, saturated water content (s) and residual water content (r) decreased, and scaling () and shape (n) parameters increased significantly due to oil-induced water repellency. The Ks of 1% TPHs-treated samples (i.e., 5.64 cm h-1) was significantly lower than that of control (i.e., 7.98 cm h-1). The s and r significantly decreased by 1% oil contamination (i.e., 0.457 and 0.112 cm3 cm-3) compared to the control (i.e., 0.547 and 0.122 cm3 cm-3), respectively. However, the parameters  and n were significantly greater in the 1% TPHs-treated samples (i.e., 0.240 cm-1 and 1.56) compared to the control (i.e., 0.130 cm-1 and 1.36), respectively. Physical weathering significantly increased s. The The Ks and Macro-P were significantly greater in the sandy loam soil whereas the Meso-P and Micro-P were significantly greater in the clay loam soil. The FC, PWP and AWC were significantly greater in the clay loam soil than in the sandy loam soil. The FC, PWP, Meso-P and Micro-P decreased but the Macro-P and SDexter increased in the oil-contaminated soil samples. The AWC significantly decreased from 0.084 (control) to 0.049 cm3 cm-3 due to 1% oil contamination. Physical weathering intensified the oil-induced water repellency (i.e., an incement in WDPT from 23.9 in repacked soil to 30.2 s in weathered soil), and reduced water retention in the sandy loam soil more than in the clay loam soil. The Ks, Macro-P and Micro-P were significantly greater in the weathered soil samples than in the repacked ones.Conclusion: As coarse-textured soils with low specific surface area are more prone to water repellency compared to fine-textured soils, they became water-repellent quicker upon physical weathering. It seems that physical weathering stimulated soil structure formation and intensified the oil-induced water repellency. The findings of this study are important for the management of oil contamination in different soil (texture and structure) conditions.

Background and Objectives: Indiscriminate use of water resources and the occurrence of drought in recent years have caused many problems in the country's water resources. The increasing shortage of water resources and high irrigation costs require developing new irrigation methods for optimal water consumption, which can minimize the amount of water used to produce yields. Evapotranspiration is one of the most important parameters needed to estimate the water balance in any ecosystem. Evapotranspiration is an essential parameter in the hydrological cycle process in natural ecosystems, which links the water and energy balance of the earth's surface with the atmosphere. Reference evapotranspiration (ET0) plays an important role in the availability of water resources and stimulating the hydrological effect of climate change. Accurate estimation of ET0 is necessary for forecasting climate changes, predicting and monitoring droughts, assessing the lack of availability of water resources, assessing crop water needs, and planning irrigation. FAO's Penman-Monteith method is known as a standard reference method for estimating ET0. However, this model and, in general, water balance-based assessment methods require accurate and long-term meteorological data, which are not always and everywhere available. Therefore, alternative methods for predicting ET0 at different temporal and spatial scales should be developed, which are easily applied and require fewer input data without compromising the estimation accuracy. Also, due to the high rate of evapotranspiration in the coastal and central stations of the country, so far, few studies have predicted the ET0 parameter. Therefore, this study was carried out to predict daily reference evapotranspiration in Isfahan and Astara stations.Methodology: The current study is forecasting daily reference evapotranspiration in two stations of Astara and Isfahan using Gaussian Process Regression (GPR), Support Vector Regression (SVR), M5P tree model, and M5Rules linear regression. For this purpose, the daily meteorological data of the stations including average temperature, minimum temperature, maximum temperature, average relative humidity, minimum relative humidity, maximum relative humidity, wind speed, and sunshine hours during the period of 1990-2021 as inputs to the models was used. Also, to evaluate the effectiveness of the models, the evaluation criteria of determination coefficient (R2), root mean square error (RMSE), Nash-Sutcliffe coefficient (NS), and Wilmott's index of agreement (WI) were used.Findings: The evaluation of the results of different scenarios of the GPR model in Astara station showed that the fifth scenario was recognized as the best scenario of this model due to having a lower error value (RMSE=1.52 mm day-1). For the M5Rules model, the fifth scenario has performed better than the other scenarios of the M5Rules model due to having fewer inputs and similar errors compared to the sixth to eighth scenarios (RMSE=1.42 mm day-1). In the M5P model, the fifth scenario has a higher accuracy than the other scenarios due to having a lower error value (RMSE=1.42 mm day-1). For the SVR model, the sixth scenario with the least error (RMSE=1.58 mm day-1) was selected as the best scenario compared to other scenarios of the SVR model. For the Isfahan station, for the GPR model, the fifth scenario has performed better than the other scenarios due to having fewer inputs. The comparison of M5Rules model scenarios also showed that the eighth scenario with RMSE=1.85 (mm day-1), had higher accuracy than other scenarios. The seventh scenario of the M5P model has performed better than other scenarios due to its RMSE=1.86 (mm day-1). Finally, the evaluation of SVR model scenarios showed that the eighth scenario with RMSE=1.88 (mm day-1) had a better performance than other scenarios. Conclusion: The comparison of the models used to predict daily reference evapotranspiration in Astara station showed that the fifth scenario of M5P and M5Rules models having evaluation criteria of R2=0.76, RMSE=1.42 (mm day-1), NS=0.7 and WI=0.89 had the highest accuracy compared to other models and showed the best performance. Also, the evaluation of the results of the models in Isfahan station showed that the eighth scenario of the M5Rules model, having the evaluation criteria of R2=0.8, RMSE=1.85 (mm day-1), NS=0.8 and WI=0.94 had the best performance compared to other models and the M5Rules model was selected as the best model. Also, the seventh scenario of the M5P model had almost the same performance as the eighth scenario of the M5Rules model and showed a good performance. Therefore, M5P and M5Rules models successfully predicted reference evapotranspiration. One of the limitations of the present study is the lack of access to dew point temperature and solar radiation data. Therefore, the use of these parameters is suggested for further studies.

Background an ObjectivesThe utilization of traditional micronutrients faces certain constraints, such as the significant retention of micronutrients in the soil. This can occur due to robust adsorption reactions to clays and organic matter, or the formation of insoluble compounds in the soil. These factors greatly diminish the effectiveness of micronutrient fertilizers. The environmental concerns and limited effectiveness linked to conventional fertilizers motivate the pursuit of innovative fertilizers with delayed release and enhanced performance. A possible solution that has been explored for these issues is the utilization of slow-release fertilizers (SRFs) or controlled-release fertilizers (CRFs). These fertilizers deliver vital nutrients to plants at a slower pace compared to conventional fertilizers. The release mechanisms of these CRFs are dependent on either diffusion through their coating or gradual hydrolysis. Yet, soil characteristics like moisture level, pH, ion concentration, and temperature also play a role in influencing nutrient release through hydrolysis or diffusion. Hence, there exists a potential disparity between the speed at which micronutrients are released into the soil and the necessary pace of nutrient absorption by crops. Graphene oxide (GO) stands out as a common material for crafting slow-release fertilizers (SRFs). Given GO's strong affinity for metal ions and its role in ferrying therapeutic compounds, it's logical to envision GO being effectively employed as a transporter for plant micronutrients. In this study, we introduce an innovative approach to tackle these constraints, showcasing the utility of GO sheets as novel carriers for efficiently loading plant micronutrients. This technique finds application in creating advanced fertilizers that enable gradual and sustained release.MethodologyIn this document, we present the creation of a novel carrier system using sheets of graphene oxide (GO). These sheets are capable of efficiently carrying plant micronutrients, allowing for a controlled and gradual release. To demonstrate this idea, we utilized zinc (Zn) and copper (Cu) as examples of micronutrients, loading them onto the GO sheets to formulate a fertilizer based on GO. We verified the chemical composition and successful loading of both nutrients onto the GO sheets using techniques such as X-ray photoelectron spectroscopy and thermogravimetric analysis. FindingsThe prepared Zn-graphene oxide (Zn−GO) and Cu-graphene oxide (Cu−GO) fertilizers showed a biphasic dissolution behavior compared to that of commercial zinc sulfate and copper sulfate fertilizer granules, displaying desirable fast and slow micronutrient release. A visualization method and chemical analysis were used to assess the release and diffusion of Cu and Zn in soil from GO-based fertilizers compared with commercial soluble fertilizers to demonstrate the advantages of GO carriers and show their capability to be used as a generic platform for macro- and micronutrients delivery. The results of kinetic rate of adsorption show a significant increase in adsorption of both ions at the beginning of the process (first 10 min), with slow increase after 10−20 min and reaching the maximum after 120 min. In the case of ZnSO4 and Zn−GO granules, similar amounts of Zn were recovered at >9 mm from the granules, 28 and 25%, respectively. In soil with CuSO4 granules, 29 % of the fertilizer Cu was recovered at >9 mm, whereas in soil with Cu−GO granules, 18 % of the fertilizer Cu was recovered in this zone. A pot trial demonstrated that Zn and Cu uptake by lettuce was higher when using GO-based fertilizers compared to that when using standard zinc or copper salts. ConclusionThe findings revealed that solid pellet forms of micronutrient fertilizers (Zn−GO and Cu−GO) exhibited a notable capacity for nutrient retention (over 10%). This capacity is attributed to GO's substantial surface area and numerous oxygen binding sites on its surface and edges, facilitating the binding of micronutrient ions. The carrier based on GO exhibited a two-phase nutrient release profile, enabling the supply of micronutrients through both rapid release (approximately 40% within 5 hours) and gradual sustained release. This release pattern is highly advantageous for crops, as it meets the high nutrient demands during seedling establishment and provides a slower, continuous release during later growth stages. The impressive nutrient retention and favorable release properties of GO-based carriers make them an attractive choice for loading various nutrients (both macro and micro) and their combinations. Consequently, they have the potential to serve as versatile carriers, ushering in a new era of advanced Slow-Release Fertilizers (SRFs).

Background and Objectives Soil resources are being depleted of nutrients and soil potential for food production is reducing. Among the primary nutrients, potassium is an essential nutrient for productivity, and food quality and has numerous functions in the plant system. Grapes need potassium to build vine strength and sustain adequate vigor. The Jowzan Vally a rural district in Malayer county, Hamadan province, Iran was formally recognized as a Globally Important Agricultural Heritage System (GIAHS) because of its traditional grape cultivation system. Therefore the fractions of soil’s potassium and fertilizer potassium availability index (AI) in some vineyards soil of Malayer county, which is one of the important regions of grape production in the country, were carried out. This study was done to investigate the potassium fertility of the vineyard soil of Malayer county.Methodology Twenty topsoil (0-30 cm) samples were collected from different vineyards in Malayer county. Soils were analyzed for some physical and chemical properties. Different fractions of potassium (solution, exchangeable, non-exchangeable, and structural potassium) were determined and the mineral components of clay were assessed by X-ray Diffraction (XRD) on oriented samples. Potassium fixation and fertilizer potassium availability index (AI) were determined after the soil samples had been treated with increasing rates of potassium. Soil samples were equilibrated at field capacity condition for 21 days at 25 ± 2°C after the addition of 0, 25, 75, 225, and 675 mg potassium kg–1. To determine the fertilizer potassium availability index (AI), the linear relation between the amount of potassium added to soil and the amount of potassium extracted with ammonium acetate was determined. All experiments were run in three replicates. The correlations between soil properties and fertilizer potassium availability index (AI) with potassium fractions were determined. Findings The types of minerals in the studied soils were similar and mainly included illite, chlorite, palygorskite, smectite, and low amounts of vermiculite and kaolinite, but their relative amounts were different. The average solution, exchangeable, non-exchangeable, and structural potassium concentrations in soils were 52, 314, 704, and 12381 mg kg-1, respectively. There was no deficiency of potassium in the studied soils and the concentration of potassium was at the optimal level, except for soil numbers 18 and 19. A negative and significant correlation was obtained between solution potassium concentration and the percentage of calcium carbonate equivalent in soils (r= -0.53, p≤0.05). The exchangeable potassium concentration shows a significant correlation with cation exchange capacity (r=0.48, p≤0.05), and pH (r= 0.48, p≤0.05). There was a negative and significant correlation between structural potassium and calcium carbonate equivalent percentage in soils (r= -0.48, p≤0.05). After 21 days of incubation, all three fractions of potassium (solution, exchangeable, and non-exchangeable) have increased in the studied soils. The percentage increase of solution, exchangeable, and non-exchangeable potassium was between 6 to 23%, 60 to 89%, and less than 1 to 34%, respectively. A significant part of the potassium added to the soils entered the exchangeable fraction. Values of fertilizer potassium availability index (AI) ranged from 0.87 to 1.38. In 35% of soils including the Jowzan area (one of the Globally Important Agricultural Heritage Systems), potassium fixation (AI less than one) and evidence of potassium depletion were observed. The highest increase in the percentage of non-exchangeable potassium was observed in soils with fertilizer potassium availability index of less than 1. The range of increase of non-exchangeable potassium in these soils was between 7.6 and 34%. There wasn’t any correlation between the fertilizer potassium availability index and soil properties. Mineralogical results showed that in soils where potassium fixation has occurred, illite is the most abundant mineral.Conclusion Soil mineralogy and total potassium values showed that most of the studied soils are fertile in terms of potassium, and the weathering of potassium minerals provides the potassium needed by plants. Nevertheless, it is recommended to manage the consumption of potassium fertilizers in the vineyards where potassium fixation was observed. Also, due to the presence of potassium-fixing clay minerals in the soil, the possibility of potassium fixation in other vineyards is predicted in case of improper management. Continued potassium export without potassium supply will lead to its eventual depletion in the soil. It is also recommended to study the potassium fixation capacity in the sand and silt components of the vineyards.

Introduction Erosion and deposition cause irreparable damage to water construction projects. Among these damages, we can mention the accumulation of sediment behind the dams and the reduction of their useful volume, the destruction of structures, the reduction of capacity and the increase in the maintenance cost of irrigation canals. On the other hand, sediment transport has an effect on water quality indicators in terms of drinking and agriculture. Accurate estimation of river suspended sediment load from various aspects of water resources engineering, environmental issues and water quality is of particular importance. In this regard, the hydrological models of the basin have not shown proper efficiency in estimating the amount of suspended sediment, due to the many influencing factors. Most of the simulation studies of suspended sediment estimation are based only on the flow rate of the basin outlet, and the obtained results are proof of their inefficiency. In the meantime, the development and use of new sediment estimation methods that are easy to use in addition to sufficient accuracy will play an important role. Nowadays, the fuzzy and neural intelligent conductor system has found many applications in various water engineering problems, including sedimentation, due to its ability to solve complex and nonlinear phenomena. Due to the great importance of sediment transport in the optimal use of water resources and the design of dams, it is very necessary to obtain an accurate method for estimating the amount of suspended sediment load in rivers.Materials and Methods The purpose of this research is to evaluate and compare the two methods of support vector machine models (SVM) and group data control method (GMDH) in estimating the suspended sediment load of the Pol Doab station of Qarachai River in Markazi Province and comparing it with the results of the measuring curve. is for this purpose, the daily data of discharge, sediment, temperature and rainfall parameters of Shazand Pol Doab station were used. For this work, 13 scenarios and different combinations of parameters were defined. Then the results of the two methods were compared with each other and with the results of the measuring curve. Finally, the best method was suggested. For this purpose, library and field studies and review of related sources, statistics and information were collected. The statistics of temperature, rainfall, daily average discharge of stream and sediment measured daily during a long-term statistical period of 40 years at Pol Doab Hydrometry Station were received from the Meteorology and Regional Water Department of Markazi Province. The received data were categorized and converted into the input format of the models. According to the discharge and corresponding sediment, the curve of the sediment gauge was drawn and its equation was obtained. Appropriate patterns of input variables were selected based on trial and error. Considering that the mentioned parameters have a historical course, therefore, the design of the input patterns of soft computing models should be done based on time delays (like what is discussed in the analysis and forecasting of time series). Then the model was taken for each input and output pattern. In the next step, the most appropriate time delay of the input parameters in the modeling, which had a higher R2 determination coefficient and a lower root mean square error (RMSE) was selected. In this research, 70% of research data was used as training and 30% for validation and testing. Finally, two data-mining methods were compared with each other and also with gauge curve and observational data.Results and Discussion The results obtained from this research indicated the acceptable performance of the methods used in predicting suspended sediment amounts. Comparing the results of GMDH, SVR and SRC models shows the superiority of GMDH and SVR models in predicting suspended sediment values compared to Verdi model number 6. The results showed the acceptable performance of the GMDH model with the highest R2 determination coefficient of 0.99 and the lowest root mean square error of 83 tons per day. According to the obtained results, it can be said that the GMDH model as a powerful and high-speed model can be used to model suspended sediment. The results of the research showed that both data-mining methods have far better efficiency and accuracy in estimating the suspended load of river sediment than the sediment gauge curve. Data mining-based methods can be used as an alternative to estimate the river's suspended load. It should be noted that due to climate change and droughts, industrial development, colonization of land use and changes in the morphology of watersheds, the obtained results cannot be used forever at any time, but should be used whenever the models need to be updated. Another weakness of the models is that with the increase in the number of developed layers, the accuracy of the produced answers increases, but the produced relationships between the input and output variables become very complicated. Conclusions The results of modeling with (SVM) showed that scenario number 6, which includes discharge at the current time and discharge and sediment with a time delay step, with the highest determination coefficient R2 with a value of 0.98 and the lowest root mean square error RMSE equal to 185 kg per day. It performs better in other scenarios. In the next step, the best model selection model (SVM) was used as the input of the GMDH model. The results were compared with the model (SVM) and sediment gauge curve. The results show the acceptable performance of the GMDH model with the highest R2 determination coefficient of 0.99 and the lowest root mean square error of 83 kg per day compared to the other two methods. The obtained results showed that both investigated data mining methods provide much better results than the sediment gauge curve. The coefficients and functions used to calibrate the intelligent models used in this research can be very useful for estimating the suspended sediments of nearby stations without statistics having the same geological and hydrological conditions at the regional level.

IntroductionAvailable water holding capacity (AWHC) is a key property for quantifying the amount of water available to plants. This c property determines the amount of water required for the crop and the irrigation time interval and is related to the inherent productivity of the soil. Determining the homogeneous zones of available water-holding capacity management is a possible way to evaluate the contribution of the soil in the optimal input of irrigation water in paddy fields. Because with its help, it is possible to manage the appropriate time of drying and wetting of paddy fields in intermittent irrigation. The rice fields of Guilan province, located in the north of Iran, with an area of about 238,000 hectares, are one of the most important rice cultivation areas because more than 30% of the country's rice is produced in this area. Irrigation in this area is done in the form of uniform flooding for easier transfer of rice seedlings, better water retention and weed control. In recent years, due to drought, population growth and increasing urban and industrial demand for water and inefficient management of flood irrigation, an attempt has been made to manage irrigation in the form of intermittent irrigation. Therefore, determining the homogeneous zones of water storage capacity management is a possible way to evaluate the contribution of soil in the optimal input of irrigation water in paddy fields. Because with its help, it is possible to manage the appropriate time of drying and wetting of paddy fields in intermittent irrigation. Water resource management is a priority to reduce productivity instability and negative socio-economic effects. For this purpose, homogeneous water storage capacity management zones were determined in Kouchesfahan region to investigate the physical-hydraulic conditions of paddy soils, dividing the entire region into zones with the same potential for water storage capacity and investigating its relationship with rice yield. MethodologyA total of 131 undisturbed and undisturbed soil samples with uniform geographic distribution were prepared from the rice root growth area and some chemical, fertility and physical-hydraulic properties were measured. Rice yield was also measured in most of the soil sampling points. Then, among 14 characteristics, seven characteristics (clay, organic carbon, linear expansion coefficient, saturated hydraulic conductivity, average particle diameter, accessible water and integral energy) that can affect the water holding capacity in the soil were selected. The number of homogeneous zones of water storage capacity was determined using two statistics, fuzzy efficiency index and modified classification entropy index. Then, by using the concepts related to algebraic maps, the integration of information layers was done in the GIS environment and the relevant maps were prepared.Result and discussionThe results of the fuzzy efficiency index and the entropy index showed that the investigated area can be divided into four water storage capacity areas. The lowest and highest value of the average yield was seen in the first and fourth zones, respectively. A significant difference was seen between available water, organic carbon, COLE, integral energy and Saturated Hydraulic Conductivity (Ks) in four management zones, but no significant difference was seen in the amount of clay and the mean diameter of the pores. In the first zone, organic carbon, Coefficient of linear extensibility (COLE), Mean of Soil Pore Size Distribution (dmean) and Ks showed the lowest values, but in the fourth zone, all these properties have the opposite behavior. These results were showed that the available water-holding capacity ty increases from zone one to zone four. Therefore, zones one and two will be particularly sensitive during drought and lack of moisture during the growing season, and the management of these zones needs special attention. In these zones, the irrigation cycle (irrigation time interval) should be shorter than the other two areas, in order to avoid the occurrence of drought stress. The soils of the studied area were uneven in terms of water retention. These results showed that the uniform (fixed) management of water consumption, in addition to increasing costs, can also lead to the waste of a large amount of water. In this situation, location-specific irrigation management can be more efficient in sustainable economic production.The comparison of the estimation map of homogeneous zones shows the water storage capacity and yield, in some zones, although the soil conditions are suitable in terms of moisture conditions, the yield is not in optimal conditions. It seems that until the state of fertility is not favorable, physical conditions cannot show their effects in performance well. In other words, until the lack of fertility is not resolved, restrictions or suitable physical conditions will not have clear effects on performance.

AbstractBackground and ObjectivesSoil compaction is a crucial factor that limits plant growth and reduces yield. To assess the level of compaction, the compaction curve is used, which shows the relationship between compressive stress and void ratio. This curve comprises three main components: pre-compression stress, compression index, and swelling index. The soil behaves elastically along the swelling line but becomes plastic and irreversible at the end of the virgin compaction line. The point where these two lines intersect is known as pre-compaction stress. The soil swelling index indicates its resilience and elasticity, while the compaction index reflects its ability to resist or undergo compaction. Some researchers have used the ratio of swelling index to compaction index to express soil's ability to recover after being subjected to stress. As long as applied stress does not exceed pre-compaction stress, soil exhibits elastic properties. To date, no comprehensive study has been conducted on how tillage type and cover crop type affect confined compression curve parameters. Therefore, this research aims to investigate how changing tillage systems and cover crop types impact soil compaction characteristics at different suctions.MethodologyThis study was conducted at Bu-Ali Sina University, Hamedan, Iran, to investigate the effect of tillage type and cover crop type on the components of the confined compression curve. The cover crop factor was tested in three levels: Vicia ash, Lathyrus sativus, and no cover crop. The tillage factor was tested in three levels: conventional tillage, minimum tillage, and no tillage. The experiment was designed as a randomized complete block factorial with three replications over two consecutive crop years. The Experiments were conducted at three suctions of 6, 30, and 1500 kPa. The confined compression curve was measured using a uniaxial device under a loading rate of 1 mm/min. The test consisted of two stages: loading and unloading. During the loading stage, 100 readings were taken at 0.01 mm intervals with an additional force of 10 kPa applied to the sample at each interval. During the unloading stage, 33 readings were taken at 0.03 mm intervals. Finally, the components of the confined compaction curve including pre-compaction stress, compaction index, and swelling index were determined.FindingsThe results indicated that the highest compaction index values for suction levels of 30 and 1500 kPa were observed in the tillage treatment without cover crops, with values of 0.63 and 0.75, respectively. The effectiveness of tillage and cover crop types was found to be dependent on soil suction levels, with significant changes in soil compaction occurring at lower suctions. Conservation tillage was observed to improve soil compaction compared to conventional tillage. At the suction level of 6 kPa, the cover crop had a significant effect (p < 0.05) on the swelling index, while the effect of tillage on this parameter was not significant. The reduction in compaction index due to cover crop application may be attributed to increased binding properties of soil particles, reduced deformation against external forces, and increased soil resilience. At the suction level of 6 kPa, higher moisture content resulted in differences in mechanical characteristics of the soil due to different cultivation systems and plant types. Overall, the results indicated that an increase in soil suction leads to an increase in pre-compression stress. However, no significant changes were observed in the three parameters investigated at suctions of 1500 kPa and 30 kPa. It is possible that the interaction between tillage type, cover crop type, and moisture content at this suction level contributed to the increase in pre-compaction stress observed in the conservation tillage-cover crop treatment. This may be due to improvements in soil structure, which have a significant impact on soil compaction properties. At the matric suction of 1500 kPa, the highest compaction index value was observed in the tillage treatment without cover crops (0.754). At lower suctions, cover crops were found to reduce compressibility by increasing soil elasticity, while treatments without cover crops were more susceptible to compaction.ConclusionIn conclusion, the study investigated the impact of tillage practices, cover crop types, and soil suction levels on soil compaction properties. The findings revealed that the compaction index values were highest in the tillage treatment without cover crops at suction levels of 30 and 1500 kPa, indicating greater susceptibility to compaction in the absence of cover crops. The effectiveness of tillage and cover crops varied depending on soil suction levels, with notable changes in compaction occurring at lower suctions. It was observed that treatments that increase organic matter in the soil, decrease soil compressibility. Overall, the results have shown that using cover crops and conservation tillage systems in semi-arid areas plays an important role in reducing soil compaction.