Research Article
majid arabfard; ali shahnazari; Mirkhaleg Ziatabar Ahmadi
Abstract
Introduction: The use of commonly known irrigation methods (especially surface irrigation or even irrigation under pressure) is limited due to the specific physical characteristics of keeping moisture and lowering the water holding capacity. In sandy beaches or desert plains (called sandstones) with ...
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Introduction: The use of commonly known irrigation methods (especially surface irrigation or even irrigation under pressure) is limited due to the specific physical characteristics of keeping moisture and lowering the water holding capacity. In sandy beaches or desert plains (called sandstones) with mentioned physical characteristics. lack of nutrients necessary for plant growth restrict the commonly known irrigation application. Gravity Drip Irrigation (GDI) is a new method that avoids the use of extra energy (pumping station). The total amount of pressure head required by the GDI for fields with a maximum area of 100 hectares is between 1 and 3 meters height. The main purpose of GDI is to reduce the required pressure by the drippers. The utilization of drip tape irrigation as one of the GDI methods has been considered in Iran in recent years. Several studies have been carried out in this regard, each of which pursues specific goals. The GDI benefits includes: reducing water consumption per unit area while increasing the moisture content of the plant root zone, increasing water use productivity, the possibility of irrigation in uneven terrain, reducing weed, pests and diseases damage, ease of distribution of fertilizer, requires lower pressure which consequences to lower cost and energy in the production process. Pot irrigation method is one of the most effective methods for irrigating in these conditions with rough terrain, coarse texture and light soils with high water penetration and saline water which surface irrigation methods normally cannot be used. The application of methods that can provide optimal irrigation conditions for such soils with their specific characteristics, such as delay in water infiltration and low outflow, can lead to improved physical conditions and optimal management of these soils.
Materials and Methods: This research was carried out in the first four months of 2016 in a sandy field located in a part of the agricultural land of Jihad-e-Tavan Co. in Kashan city. In this research, according to the custom of the region, the local watermelon of Sunbek district in Aran and Bidgol city, were chosen as a study plant. A factorial design in a completely randomized block including three main treatments of localized irrigation and three irrigation treatments (total of nine treatments) with three replications, as well as furrow irrigation treatment as control were applied. In each row, 12 plants were planted with a distance of one meter on a row and three meters between rows, on an area of 1080 (36×30) square meters.
Results and Discussion: The role of pulsed irrigation cycle in providing favorable growth conditions and consequently increasing yield can be achieved by comparing the performance of localized treatments and control treatment. The Duncan's test results for number of fruits and yield comparison using selected irrigation methods showed that there was no significant difference in the number of watermelons and their weight at the probability level of 1% and 5%. For different irrigation methods, there was a significant difference between yield and number of watermelons at same probability level. By the end of the 110 days after planting, the yield in furrow irrigation, pot irrigation, drip tape and GDI were 11426, 1224, 7527 and 11457 kg/ha, respectively. The improvement percentage of yield in comparison with the control treatment, were 85%, 1034% and 1626% in pot irrigation, drip tape and GDI, respectively. This research results revealed that the ratio of water used to yield in furrow treatments, pot, drip tape and GDI were 1.18, 5.55, 0.9 and 0.09 m3/kg. Also, considering the amount of water used for each treatment, 49.7 and 23.4 percent decrement in applied water in drip tape and GDI and 371.2 percent increment in applied water in pot irrigation observed per kilograms of watermelon produced compared to the conventional irrigation method (furrow irrigation). Highest water productivity index achieved in GDI among the four methods studied, as much as 1.7 kg of watermelon produced per cubic meter of water.
Conclusion: In this study, the efficiency of more than 80% achieved in furrow irrigation in sandy soil. Improvement in irrigation efficiency in these soils can be achieved by managing parameters involved like furrow length, time and irrigation discharge. The results showed that with the amount of water consumed equal to 6790 cm3/ha in each of the gravity localized irrigation methods and 13452 cm3/ha in the control treatment, the watermelon yield in pot irrigation, gravity drip, drip tape and furrow irrigation methods were 1224, 11457, 7527 and 11426 kg/ha, respectively, and the water productivity index was equal to 0.2, 1.7, 1.1 and 0.8 kg/ha.m3, respectively. In comparison with the one-day irrigation interval, using pulses irrigation in localized irrigation, irrigation efficiency increased from 87% to 98%. In general, by using localized irrigation in comparison with furrow irrigation in sandy soils, in addition to increasing water productivity, high yield could be achieved in plants like watermelon.
Research Article
Naser Arya Azar; Abolfazl Majnooni Heris; Reza delearhasannia
Abstract
Introduction: Water as the most limiting factor in agricultural production plays an important role in providing food for population of the country. Therefore, it is necessary to use optimal water resources of the country and increased its productivity. So to improve irrigation efficiency, as ...
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Introduction: Water as the most limiting factor in agricultural production plays an important role in providing food for population of the country. Therefore, it is necessary to use optimal water resources of the country and increased its productivity. So to improve irrigation efficiency, as well as the proper use of land and available water resources the best irrigation system should be used to supply plant water requirement. This selection is influenced by various factors such as cultivar type, available water content, water quality, soil characteristics, climatic conditions, selective cultivar pattern, labor force skill, and etc. The mentioned effective parameters depending on the region may change. Therefore, it is necessary to identify the homogenies areas for application of irrigation system.
Materials and Methods: The study area is the Ajichay River Basin in East Azarbaijan Province. This basin is located between 37° 30' to 38 ° '30 northern and 45° 24 ' 47° 53' eastern. In this study AHP method and GIS were used for identifying homogeneous zones of irrigated and rainfed areas. Analysis Hierarchical Process method is one of the most comprehensive systems designed for decision making with multiple criteria. This method was first proposed by Thomas El Saaty in 1980, which is based on paired comparisons. This gives managers the opportunity to study different scenarios. In the AHP model, we construct a matrix for comparing two factors. It has two important features, 1- Considering multiple quantitative and qualitative factors in problem solving and 2- The ability to analysis complex issues through hierarchical factors. In this study, to determine the homogeneous irrigation regions, first, the criteria was determined. In AHP method questionnaires were prepared, to score, these questionnaires were provided to the experts of this field. Then using the AHP method the criteria was compared with together. Finally, for each of the criteria, the interpolation maps in the GIS using geostatistical methods were obtained. These maps were divided into different zones using available tables and resources. The maps were combined in their scores in GIS and homogeneous irrigation areas (sprinkler, drip and surface irrigation systems) were selected.
Results and Discussion: In this study, the agricultural lands, including under irrigation lands, dry farming and gardens, were distinguished from non-cultivated lands. In agricultural land of Tabriz plain, applying sprinkler irrigation system has moderate restrictions and some areas face severe restrictions. In the southern parts of Bostanabad plain, the implementation of the sprinkler irrigation system is suitable. The possibility of sprinkler irrigation in dry farming lands was also investigated. Lands that located in the Bostanabad, Heris and Sarab plains will be relatively suitable for sprinkler irrigation. But for the Tabriz plain, the underground water and soil quality are low, applying sprinkler irrigation system has moderate restrictions. However, in Sarab plain, the appropriate area is visible. Implementation of drip irrigation system in the study area, in a large part of the Sarab plain and the southern parts of the plain of Bostanabad were appropriately determined. But in Tabriz plain and lands near the Urmia Lake, the implementation of this system has severe restriction. Like sprinkler irrigation, agricultural land of Tabriz plain has a moderate restrictions. Most areas of Heris, Bostanabad and Sarab plains, for applying this system will be relatively suitable. According to expert, water SAR and land gradients have more effect on the implementation of surface irrigation systems. If we can correct these two parameters with management and planning tasks, the implementation of this system will be appropriate in many areas of the basin. Most agricultural land has a moderate restriction on the implementation of this system.
Conclusion: The AjiChay Basin with an equivalent area of 12600 km2 is one of the largest sub basins in Lake Urmia basin. Since agriculture is important in this basin and also the quality of irrigation water in some parts of this basin is low, therefore, it is essential to pay attention to the type of irrigation method. Considering the parameters of water, climate and soil, suitable and unsuitable areas for surface irrigation, sprinkler and drip irrigation systems were determined. Thus, implementing irrigation system in agricultural lands in the margins of Lake Urmia and in some areas, will be severe restrictions. Getting away from Lake Urmia the groundwater quality, which is mainly used for agriculture, using irrigation systems is relatively appropriate.
Research Article
Malihe Ebrahimi; Hossein Asadi; Arezoo Sharifi; Eisa Ebrahimi
Abstract
Introduction: The study of physical properties of suspended sediments is one of the main topics in river studies. Sediment size distribution is one of the sediment physical properties which indicate the relation between the sediment source and its sedimentation process in watersheds. It is also important ...
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Introduction: The study of physical properties of suspended sediments is one of the main topics in river studies. Sediment size distribution is one of the sediment physical properties which indicate the relation between the sediment source and its sedimentation process in watersheds. It is also important for prediction of the load of non-point source pollution, and for planning sediment trap structures. The Anzali Wetland, located on the southern coast of the Caspian Sea in northern Iran, is a large complex of freshwater lagoons with extensive reed-beds, shallow impoundments and seasonal flooded meadows. Environmental conditions in the Anzali Wetland have been degraded due to the increased inflow of sewerage, wastewater and solid waste from the industry, agriculture and urban area, and sediment from the upper stream mountainous area. The lagoon has decreased in size since the 1930s to less than a quarter of its former extent. The aim of the present study was to assess the changes in size distribution of suspended sediment in Pasikhan River as the most important river interring to Anzali Wetland.
Material and Methods: Pasikhan River originates from the South Mountains, has two branches namely Siahmezgi and Imamzadeh Ebrahim. The sampling carried out during a seven month time period (October 2013 to April 2014) at two hydrometric stations; Mobarakabad (upstream) and Nokhaleh (downstream). The samples were collected in 15 days intervals by depth-integration technique at normal condition. Particle size distribution was measured by Pipette method based on Stocks law. The mean weight diameter (MWD) of sediment particles was calculated, the sediment size distribution curve was drawn and the median grain size (d50) was calculated. According to the European classification, the particles size distribution was divided into four groups of fine sand (0.2 mm), coarse silts (0.06 mm), medium silt (0.02 mm), and fine silt and clay (equal to and less than 0.006 mm). The data were compared for each sampling time for both Stations. Flow discharge and suspended sediment load were also determined at each sampling date.
Results and Discussion: At the Nokhaleh station, the maximum observed flow discharge and sediment concentration were 51.4 m3/s and 4.162 g/L, occurred in February 4, 2014 and November 3, 2013, respectively. The highest flow discharge and sediment concentration of the Mobarakabad were 9.8 m3/s and 2.633 g/L which were observed on February 19, 2014 and April 4, 2014, respectively. These changes and differences were partly due to topography and land use differences between upland and lowland and partly due to rainfall pattern. Results showed that the MWD and d50 were 0.062 and 0.052 mm on average, respectively at Mobarakabad station, and 0.055 and 0.051 mm, respectively at Nowkhaleh station. The maximum values of MWD and d50 were observed to be 0.07 and 0.061 mm, respectively at normal condition at Mobarakabad station. The study of sediment size distribution indicated that the particles smaller than 2 mm comprised 83-94 percent of the suspended sediment at Mobarakabad station, and 87-99 percent at Nokhaleh station. The percentage of particles smaller than 0.02 mm were observed to be 12-33 and 10-64 at Mobarakabad and Noukhaleh stations, respectively. Also the amount of fine silt and clay in suspended sediment were 3-16 and 5-24 percent at these stations. There was not any correlation between flow discharge and sediment concentration or sediment size distribution characteristics.
Conclusion: In most of the samples, there was not any relationship between the flow discharge and particle size distribution of suspended sediment which emphasize on the non-hydraulic nature of sediment transport and the effects of different factors including sediment sources, the season, transport energy, rainfall erosivity, soil erodibility and deposition process. Generally, the size of sediment particles at Mobarakabad station was coarser than Nokhaleh station. This could be due to the type of soil erosion which is different at upstream and downstream. In upstream regions, mainly because of severity of topography and vegetation cover including forest and rangeland, the occurrence of gully erosion and landslide is higher in comparison with surface soil erosion. But in downstream especially in paddy fields, the soil erosion type is mainly splash and sheet erosion. Also the cultivation practices including plowing and paddling of the field usually provides fine particles entering to the river. In addition, the river profile is very gentle at the plain before the Nokhaleh station which resulted in deposition of coarser particles.
Research Article
Habib Abedi Babaheydari; Rohallah Fatahi Nafchi; Davood Namdar
Abstract
Introduction: The existence of 35 to 45 million hectares of desert areas in Iran and many restrictions such as lack of precipitation, have caused many challenges for the development of these areas. On the other hand, improper utilization of existing resources has resulted in desertification as a natural ...
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Introduction: The existence of 35 to 45 million hectares of desert areas in Iran and many restrictions such as lack of precipitation, have caused many challenges for the development of these areas. On the other hand, improper utilization of existing resources has resulted in desertification as a natural phenomenon, which is increasing annually. The activities that have been tracked down desertification decades ago have only managed to control a very small corner (about 9.1 million hectares) of these areas. Desertification is the consequence of two challenges of climate change and freshwater scarcity. In Iran, 43.7 million hectares are desert ecosystems in the wilderness of the country, of which about 20 million hectares of desert ecosystems are affected by wind erosion. Meanwhile, 4.6 million hectares in 183 districts in 82 counties and 18 provinces of the country are considered critical wind erosion centers. In general, natural and human factors are among the main origins of desertification. In arid and semi-arid areas due to lack of precipitation, water is the most important limiting factor for plant deployment. Due to the quantitative and qualitative limitations of water resources, the survival of plants in desert areas, mainly depends on the choosing appropriate irrigation method. The purpose of this study was to compare Water Box method, which is a particular form of irrigation, with surface and drip irrigations for planting hawthorn plant, which is often used for desertification projects in semi-arid areas such as Iran.
Materials and Methods: Experiments were carried out in the research field at Shahrekord University in the coordinate 32.3526° N, 50.8261° E and 2105 meters above sea level. The study area is 7 km far from the Shahrekord synoptic meteorological station. Shahrekord climate is categorized as Dcas climate by Copenhagen division method, which is characterized by moderate cold weather conditions with warm summers. In surface and drip irrigation methods, five irrigation regimes with zero, 25, 50, 75 and 90 percent of water requirements each with three replications were applied. In the Water box method, due to the self-regulation of the system and the no possibility of deficit irrigation, experiments with 15 similar replications were performed. Plant parameters such as stem diameter, height, seedling survival percentage and water content in each treatment were measured by one-month interval and compared to each other at the end of the study.
Results: The results of this study showed that the Water Box system, while significantly reducing the amount of consumed water (92% than drip irrigation) and high survival rate of seedlings (in this research 100%), is a useful method for establishing some hawthorn seedlings for combat and control of the desertification phenomenon. The highest growth was observed in irrigation treatments with 25 percent low irrigation with 60 cm height growth. Also, the lowest growth is due to irrigation with 90 percent low irrigation. In order to compare the mean annual growth rate of treatments, data were analyzed in SPSS software using the Duncan test at a significant level of 5 percent. The highest water use efficiency was related to water Box irrigation with 2.5 cc/l, which was obtained with a relatively large distance from other treatments, while, as mentioned in the previous sections, the water consumption of this treatment 92 percent low irrigation than full drip irrigation. The lowest water use efficiency was related to irrigation with 75% irrigation, which was 0.15 m3 l-1. In total drip irrigation treatment, water use efficiency was estimated to be 0.16 cm/liter, which shows that although the growth of this treatment was in good condition, it has poor results regarding water use efficiency.
Discussion: Due to the resistance of hawthorn to drought, only three of the cultivated seedlings were dried. The percentage of viability in the Water Box method was 100 percent. However, the difference in the percentage of vitality according to Duncan's method was not significant at 5 percent level. The results of seedling survival percentage were consistent with Naseri et al.(2005). They did not observe the significant difference between irrigation treatments in terms of viability. Due to the lack of research on irrigation with the Water box system, it is recommended that other researches be carried out on the use of this system for irrigation of other (productive) species. The location of the installation and tiling of wicks is one of the things that need to be addressed in the future research.
Research Article
A. Rastegarnia; mehdi karami; M. Ghafoori
Abstract
Introduction: Water resources quality assessment of the dam sites is one of the primary studies in the designing of these structures. The main challenges in Iran are the reduction of water resources and the limitation of groundwater exploitation. Much of these resources are formed in karst water resources ...
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Introduction: Water resources quality assessment of the dam sites is one of the primary studies in the designing of these structures. The main challenges in Iran are the reduction of water resources and the limitation of groundwater exploitation. Much of these resources are formed in karst water resources in the karstic susceptible formations such as the Asmari carbonate formation in Zagros Mountain, Iran. In this study using laboratory and field studies, various parameters and indices were assessed to investigate the water resources quality of Bazoft dam site for different purposes. Bazoft dam is a double-curvature arch dam with a height of 211 meters which is located in Chaharmahal and Bakhtiari Province of Iran. The bedrock of the dam site consists of limestone and dolomite rocks of the Asmari and the Jahrom formations. The Jahrum formation formed the right abutment, the riverbed and the lower parts of the left abutment. The Asmari formation formed the rocks in the middle and upper part of the left abutment.
Materials and Methods: After field studies, chemical analyses have been performed on the collected water samples from the water resources such as springs, river and the exploratory boreholes in the dam site. PH and electrical conductivity (EC) were measured by pH meter and electrical conductivity apparatus was measured at 25 ° C. Concentration of ions such as calcium, magnesium, bicarbonate was measured by titration method. The concentration of ions such as sodium and potassium, sulfate and nitrate were measured using the Flame-Photometry, and Spectrophotometry methods, respectively.. The test error in all cases was low and the results were confirmed. The indices such as Langelier saturation index and Ryznar stability index, sodium adsorption ratio (SAR), soluble sodium percentage, residual sodium carbonate, permeability index, Kelly ratio, were calculated based on related equations. Principal factor analysis (PCA) is used to determine the most influential variables when the number of variables is investigated and the relationship between them is unknown. In this method the variables are set on the elements so that the first factor is reduced to the next factor of the variance, hence the variables that are based on the first factors are the most influential. PCA reduces the dimensions of the initial data by turning the main components around the vertical and horizontal axes of coordinates. This rotation actually increases the variance between the main components and therefore it is called Variance Maximize Varimax or orthogonal rotation. The Varimax command is one of the most common methods of orthogonal rotation that preserves the independence between the extracted agents. This method reduces the number of the larger factor loadings to the lowest number. In this method, the scree plot chart determined the number of factors extracted. Parameters of R2 and RMSE in order to investigate the performance of relations have been used. As R2 is closer to the one and the RMSE is closer to the zero, the proposed relationship will yield better performance.
Results and Discussion: Anions such as HCO3, Cl, SO4, CO3 and NO3 and cations such as Ca, Na, Mg, and K are the most, respectively. From the viewpoint of hardness, all waters are placed in the hard category. According to the percentage of Na, the spring’s water is excellent, the water of the borehole is good and the river is acceptable. The results of factor analysis showed that 87.13 percent of the water quality variations are controlled by four factors. The most important factors affecting the water quality of the dam site include EC, TDS, Na %, SAR, Cl, SO4, alkalinity, Na, and CO3 with 50.91 %. The second factor include calcium, magnesium, potassium ions with 15.82 %, the third factor include nitrate, bicarbonate, and hardness with 11.61 % and pH and carbonate with 7.17 % are fall into the fourth factor. The correlation matrix of the parameters was investigated and the accuracy of some relationships was examined on the basis of different statistical criteria. The relationships of LSI with RSI and EC with TDS in the dam site and their comparison with previously suggested equations indicated that there is a high correlation and each relationship is applicable for a particular area. Also, the trend of points obtained from each equation has the appropriate consistency but the RMSE of the assessed equations is high. EC plot against TDS to determine the relationship between the two parameters in the Bazoft dam site is TDS=0.70Ec-31.24.
Conclusion: The concentration of all assessed cations and anions is lower than the WHO permissible limit. The water resources are corrosive and all indices indicated the appropriate quality of water resources for farming and drinking.
Research Article
Arsalan Sadeghian; gholamabbas sayyad; Ahmad Farrokhian Firouzi; Mojtaba Norouzi Masir
Abstract
Introduction: Soil is one of the renewable natural resources that take a long time to get renewed; its destruction or conservation depends on how land is used and managed. Soil quality refers to soil capacity in maintaining biological fertility, sustainability in plant production and yield. Maintaining ...
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Introduction: Soil is one of the renewable natural resources that take a long time to get renewed; its destruction or conservation depends on how land is used and managed. Soil quality refers to soil capacity in maintaining biological fertility, sustainability in plant production and yield. Maintaining soil quality is essential for sustainable food production and decomposition of organic wastes. Different agronomic managements have various effects on soil quality indicators. There are few published researches about the effect of various agronomic managements on soil quality indices in arid and semi-arid regions (such as Iran). Therefore, this study was conducted to investigate and compare the effects of three different agronomic management including crop rotation-crop residue removal, monoculture-crop residue removal and monoculture-crop residue retention systems on some physical indicators of soil quality.
Materials and Methods: In this research, three farms with three crop management systems including crop rotation-crop residue removal, monoculture-crop residue removal and monoculture-crop residue retention (10 ton per hectare) systems were investigated. In the monoculture-crop residue removal treatment, wheat was continuously cultivated for 8 years. In the rotation-crop residue removal system, wheat - mung bean were cultivated in rotation for 2 years. For the monoculture-crop residue retention system, wheat was planted for 10 years, after which the post-harvest residues were mixed with topsoil (0-15 cm). One hundred twenty soil samples (40 samples from each field) were prepared by systematic sampling from 0 to 15 cm depth. In order to investigate the effect of different agronomic management on soil physical quality, some indicators including soil organic matter, total porosity, bulk density, mean weight diameter of aggregates, aggregate stability, available water capacity, penetration resistance, saturated hydraulic conductivity, and slope of retention curve at inflection point (S-index) were measured. The experiment was conducted in a randomized complete block design with four replications. Also, the mean comparison was performed using Duncan's multiple range test.
Results and Discussion: The results of analysis of variance showed that the type of crop management had a significant effect (p<0.01) on organic matter, total porosity, bulk density, mean weight diameter of aggregates, aggregate stability, available water capacity, penetration resistance, saturated hydraulic conductivity and S-index. The results of mean comparison indicated that the monoculture-crop residue removal system resulted in a significant increase in bulk density (1.31 g cm-3) and soil penetration resistance (0.4 MPa) than other systems, while the highest organic matter content (1.038 %), porosity (55.7%), mean weight diameter (1.04 mm), aggregate stability index (28%), available water capacity (0.15%), saturated hydraulic conductivity (46.17 cm h-1) and S-index (0.053) was observed in the monoculture-crop residue retention system. The most measured values for soil quality indicators were more in monoculture-crop residual retention system compared with the other treatments. The amount of S-index of soils under monoculture-crop residual retention, crop rotation-crop residues removal, and monoculture-crop residual removal systems were 0.053, 0.032 and 0.019, respectively. The high S-index value of soil under monoculture-crop residual retention system can be attributed to its suitable amount of soil organic carbon and better soil structural quality. By contrast, in monoculture-crop residue removal system, elimination of organic matter had undesirable effect on soil porosity, and aggregate stability. Furthermore, the S-index values of the soils under crop rotation-crop residues removal, and monoculture-crop residual removal systems are below the Dexter’s soil quality index threshold (0.035); therefore, the results indicated that the soils are degraded.
Conclusion: The results of this study showed that crop management plays an important role in changing soil physical quality indicators. Among the studied crop managements, monoculture-crop residue retention management system showed more positive effects on soil physical parameters than the others. Retention of crop residues on soil surface increases the soil organic matter which in turn has positive effects on soil properties such as aggregate stability, saturated hydraulic conductivity, available water content and slope of retention curve at the inflection point. On the other hand, the monoculture-crop reside removal treatment, with less soil organic matter, had more undesirable effects on agronomic soils than other treatments. Based on the results, the effect of different agronomic management systems on improving soil physical quality indexes was in the following order: monoculture-crop residue retention >crop rotation-crop residue removal > monoculture-crop residue removal. According to the results, it can be concluded that soil organic matter is the central index of soil quality, which is intensely influenced by crop management system. Therefore, in arid and semiarid areas such as Iran, monitoring of the long-time effect of agronomic management on status of soil organic matter and soil physical indices is urgent.
Research Article
Saeed Saadat; leila esmaeelnejad; hamed rezaei; Rasoul mirkhani; javad seyedmohammadi
Abstract
Introduction: Soil aggregates refers to groups of soil particles which attach to each other stronger than neighbour particles. Aggregate stability shows the capability and strength of soil aggregates to tolerate breakup when disruptive stresses and destructive forces via mechanical agricultural operation ...
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Introduction: Soil aggregates refers to groups of soil particles which attach to each other stronger than neighbour particles. Aggregate stability shows the capability and strength of soil aggregates to tolerate breakup when disruptive stresses and destructive forces via mechanical agricultural operation such as tillage and water or wind erosion are applied. Wet aggregate stability shows how well a soil can withstand raindrop impact and water erosion, while size distribution of dry aggregates can be used to predict resistance to abrasion and wind erosion. Aggregate stability changes can act as the first indicators of recovery or degradation of soils. Aggregate stability is an indicator of organic matter content, biological activity, and nutrient cycling in soil. Generally, in small aggregates (< 0.25 mm), the particles are bound by older and more stable forms of organic matter. Microbial decomposition of fresh organic matter releases products (that are less stable) that bind small aggregates into large aggregates (> 2-5 mm). Although, there is not a unique acceptable methodology that serves and applies the entire world up to now, aggregate stability has been introduced as a soil physical quality indicator. Difficulties remain when comparison of aggregate stability from different methodologies are done. The objective of the present study was to assess appropriate and satisfactory aggregate stability tests that enable to distinguish the soil physical quality condition of both arid and moist medium textured soils.
Materials and Methods: A total of 120 soil samples which contained 60 wetland samples from Guilan province with a very humid climate, average annual rainfall of 1285 mm, and average annual temperature of 16°C, and 60 samples from Fars province with dry climate, average rainfall of 225 mm, and the average annual temperature of 27°C were provided. Soil sampling was performed from surface layer (0-20 cm). Each 10 soil samples with similar texture were mixed and one soil sample for each texture was finally obtained. After air drying and sieving, soil texture and organic carbon were determined by pipette and oxidation methods, respectively. Also, undisturbed samples were taken using metal cylinders from surface layer of 5-15 cm for determination of soil saturation coefficient, soil moisture curve, and soil bulk density. Also, in order to determine the aggregate stability, Kemper and Rosenau, de Leenheer and de Boodt, as well as Le Bissonnais were used.
Results and Discussion: Among different tested methods, wet sieving using the well known fast wetting methods of Kemper & Rosenau and of Le Bissonnais presented similar results in both climates. The mean weight diameter value of both methods for assessing aggregate stability can be considered as a dependable indicator of soil structure status for comparing soils. These aggregate stability tests were in correspondence with only one out of the eight soil physical quality indicators when the entire soils were used. It was concluded that the aggregate stability should be used judiciously and in accordance with other indicators for an overall assessing of the soil physical quality condition. The great differences in the estimation of aggregate stability between KRSW and LB2 with other methods confirm that aggregate stability increases with increasing soil moisture content. This involves reducing the amount of air condensed, which results in the reduction of compressive forces on the aggregates during rapid wetting. But the lack of similarity between the KRSW and LB2 methods in terms of MWD suggests that the results of these two methods are not comparable to dry and wet soils. The difference in aggregate size distribution from all three treatments of LB method was higher in dry areas than wet areas. Only dry soils based on LB (LB1 and LB3 treatments based on MWD) (P <0.05) are comparable. In dry soils, the LB3 method is very efficient. This method involves the use of ethanol that protects the aggregate structure against dryness stresses. The lack of similarity between the MWD and other soil quality indicators describes the complexity of the soil structure, which is dependent on the location. It seems that SOC can be considered as an indicator with high correlation with the aggregate sustainability index of LB and KRFW methods, at least in the studied medium-textured soils.
Conclusion: Since only a soil quality index (SOC) had a similar trend to the sustainability index derived from these two methods (LB1 and KRFW), it can be concluded that aggregate stability should be judged and recognized correctly, along with other used soil physical indicators for a general assessment of the conditions. In case of arid land soils, efficiency of pre-wetted methods of Kemper and Rosenau and of Le Bissonnais as well as pre-wetted Le Bissonnais with mechanical slaking and shaking were similar. If a simple and rapid analysis of the structure status is needed, single tests such as fast wetted Kemper and Rosenau and Le Bissonnais can be used.
Research Article
Saman Hajinamaki; Hojat Emami; Amir Fotovat
Abstract
Introduction: Water scarcity is one of the important issues in agriculture, especially in arid and semi-arid regions of Iran. Therefore, the challenge for the agriculture in these areas is to find new sources of water for irrigation. One of the ways that has become more common in recent years is the ...
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Introduction: Water scarcity is one of the important issues in agriculture, especially in arid and semi-arid regions of Iran. Therefore, the challenge for the agriculture in these areas is to find new sources of water for irrigation. One of the ways that has become more common in recent years is the reuse of wastewater as a secondary source and replaces drinking water. The effects of irrigation with wastewater on physical, chemical and biological properties of soil have been studied by many researchers, which most of them are based on the direct use of untreated wastewater in agricultural land irrigation. In fact, a large amount of wastewater used in the agriculture is indirectly entered into the rivers, and used in the agriculture lands. Irrigation with wastewater may have effects on soil properties such as pH, EC, nutrient content, sodicity, pollutants and etc.
Materials and Methods: In order to determine the effect of irrigation by wastewater on soil properties in May 2015, several points of the Kashafrood River in the north of Mashhad were selected. The studied points were located between 59˚36ʹ- 59˚41ʹ E and 36˚19ʹ- 36˚22ʹ N geographical position. The wastewater is refined in Parkandabad station, and used for irrigation. The samples were taken from a depth of 0-30 cm in each point and three replications were regarded for them. Sampling distance was one kilometer from each other. In general, 15 points were irrigated with wastewater were selected. 12 physical, chemical and biological properties including pH, soil texture, bulk density (BD), dispersible clay (DC), mean weight diameter of aggregates (MWD), sodium adsorption ratio (SAR), organic carbon (OC), available phosphorous (P), available potassium (k), total nitrogen (TN), microbial biomass and base respiration (BR) were measured as a total data set (TDS). According to Liu and Chen the main component with an Eigen value greater than one using the PCA method were chosen as minimum data set (MDS). Within each PC, highly weighted properties were defined as those with absolute values within 10% of the highest weighted loading. When more than one variable was retained in a PC, each was considered important and was retained in the MDS if they were not correlated (r < 0.60). Among well-correlated variables within a PC, the variable having the highest correlation sum was selected for the MDS. Data analysis were performed using SPSS Statistics22 software.
Results and Discussion: The results showed that irrigation with wastewater increased biomass and BR, OC, SAR, K and stability index of soil structure. The parameters of K, TN, pH and MWD have been increased compared to the control, but were not statistically significant. Using PCA, five PCs were obtained, which PC1 and PC2 with Eigen value of 50.6 % were the most important components. The parameters of OC, SAR, TN, pH, BD, MWD, BR and K were chosen as MDS due to be changed as a result of irrigation with wastewater. Then, the correlations between these parameters in two groups of irrigated soils with wastewater and control were investigated. Organic carbon in both soil groups had the highest correlation with the SI. The SAR in both soil groups was negatively correlated with nitrogen and phosphorus. Nitrogen in irrigated soils with control was positively correlated with the SI and OC. The MWD was not correlated with any parameter. PH had shown positive correlation with microbial biomass and OC was positively correlated with BR, TN and SAR in soil controls. Potassium in the irrigated soils with wastewater had the negative and significant correlation with OC, SI, BD and MWD. Microbial respiration had a high positive correlation with SI, OC and TN in irrigated soils, which is due to carbon and nitrogen in the wastewater and causes an increase in its amount compared with the control.
Conclusion: The results showed that irrigation with wastewater caused a significant increase in parameters SI, SAR, P, BR, MBC and organic carbon in irrigated soil with wastewater and pH, MWD, TN and K had no a significant difference. On the other hand, the principal component analysis of the two groups of irrigated soils with wastewater and control had two distinct groups indicating that the irrigation with wastewater had a significant impact on the soil properties. According to the principal components analysis, eight parameters including OC, SAR, TN, MWD, BD, pH, BR and K were selected as the most important parameters to study the effects of irrigation by wastewater.
Research Article
Elahe Zorati pour; amir soltani; naser alemzadeh ansari
Abstract
Introduction: when the loss of water from the leaves by transpiration process exceeds the water in the root zone, water stress occurs. If water uptake reduction functions can predict the flow of water to the roots properly, with no need to field measurements, it is possible to determine the time of irrigation ...
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Introduction: when the loss of water from the leaves by transpiration process exceeds the water in the root zone, water stress occurs. If water uptake reduction functions can predict the flow of water to the roots properly, with no need to field measurements, it is possible to determine the time of irrigation for maximum yield with the help of chemical and physical properties of water and soil and specific plant parameters. From a conceptual point of view, two main approaches of water uptake modeling exist, which differ in the way they predict the volumetric rate of root water uptake. The microscopic models describe the water flow towards the single root. Macroscopic models are based on the principles of energy and mass transfer and described water uptake by the entire root area, regardless of the impact of individual roots. In general, macroscopic models have been considered in plant growth and soil-plant-atmosphere models. The most important models of macroscopic water uptake can be referred to the model of Feddes et al. (1978), the Van-Genuchten model (1987), the Dirksen et al. (1993) and Homaee (1999). Saraei Tabrizi et al. (2015) with an evaluation of the water uptake reduction functions under water stress conditions on basil plant showed that the Homaee (1999) model was more suitable than other models. The purpose of the present study is to evaluate the four macroscopic water uptake reduction functions of Feddes et al., (1978), Van Genuchten (1987), Dirksen et al., (1993) and Homaee (1999) in order to predict water uptake by lettuce root and determining the most suitable model to predict the reduction of water uptake of lettuce under water stress conditions.
Materials and Methods: The experiment was conducted in a completely randomized design with three replications in 2017 in the research greenhouse of Agriculture Faculty, Shahid Chamran University of Ahvaz. The experiment consisted of irrigation water at three levels (I1:100%, I2:80% and I3:60% of crop water requirement). The soil texture was medium. The cultivation was indirect (seedling) in pots of diameter 22 and height 30 cm. For this purpose, 9 pots were used. The plant's growth period was about 70 days. The irrigation was done by the manual method and by the graduated bushel. During the growing season, treatments were irrigated fifteen times. The volume of water used for treatments I3, I2 and I1 were respectively 792, 1055 and 1320 )m3.ha-1(. The weighted method was used to determine the time of irrigation and the soil moisture characteristic curve was used to measure the matric potential. 12 pots were considered as destructive ones for measuring plant weight as it was not possible to measure the weight of plants per day. In order to evaluate the water uptake reduction functions, relative transpiration was plotted against the absolute value of matric potential and the best model was determined by fitting them, to the measured data. For this purpose, the statistical indicators of the Maximum Error (ME), coefficient of determination (R2), Root Mean Square Error (RMSE), modeling efficiency (EF) and Coefficient of Residual Mass (CRM) were used.
Results and Discussion: Based on the results, the model of Homaee (1999) and the model of Van Gennuchten (1987) had the best fit on the whole range of measured data, respectively. Then, the model of Dirksen et al. (1993) and, the model of Feddes et al. (1978) were ranked. In addition, in models that |h| was smaller than 8000 cm, like Feddes et al. (1978), Van Gennuchten (1987), Dirksen et al. (1993) showed good fit and proximity to each other. Babaazadeh et al. (2017) in studying the effect of salinity and drought stress on the uptake of root water of basil, concluded that the Homaee (1999) model had the best agreement with experimental data and increasing drought stress reduced the potential of water uptake by roots. Also Saraei Tabrizi et al. (2015) concluded that the Homaee (1999) model had the best fit with the measured data and the results were in accordance with the results of this study. Based on the results of this study, for simulation of water uptake, the models of Feddes et al. (1978) and Dirksen et al. (1993) are slightly overestimated and Van Gennuchten (1987) and Homaee (1999) models have slightly underestimated. Homaee (1999) in his research was conducted that in treatment of 70% water requirement supply for alfalfa, Feddes et al. (1978) model was overestimated and other models were underestimated which are close to the results. Homaee (1999) model was more consistent compared to other water uptake models because of considering two thresholds for the model.
Conclusion: According to the results, Homaee (1999) model was better than other models (RMSE=9.14 and ). The results of the models of Feddes et al. (1978) with R2 =0.43 and RMSE = 16.46, Van Gennuchten (1987) with R2 = 0.51 and RMSE = 8.62 and Dirksen et al. (1993) with R2 = 0.48 and RMSE = 12.5 were closely related to each other.
Research Article
Moghbeli Z.; S. Sanjari; E. Adhami
Abstract
Introduction: In sustainable agriculture, it is essential to know soil various characteristics for increasing the soil productivity. The relationship between soil and geomorphology in arid and semi-arid regions has been considered by many researchers. Faryab plain is located in arid region of Kerman ...
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Introduction: In sustainable agriculture, it is essential to know soil various characteristics for increasing the soil productivity. The relationship between soil and geomorphology in arid and semi-arid regions has been considered by many researchers. Faryab plain is located in arid region of Kerman Province and has diversity in geomorphic positions and parent materials. No previous study has been conducted in this region. Therefore, the objectives of the present research were 1) to study the genesis and development of soils related to different geomorphic surfaces in Faryab region, 2) to study the physicochemical properties, clay mineralogy and micromorphology of soils, and 3) to classify the soils according to Soil Taxonomy (ST) (2014) and World Reference Base (WRB) (2015) systems and compare them.
Materials and Methods: Faryab region with a mean elevation of 630 m above sea level is located in Kerman province, south-eastern of Iran. Mean annual rainfall and temperature of the area are 160 mm and 23.8 oC, respectively. Soil temperature and moisture regimes of the area are thermic and aridic, respectively. From geological point of view, the studied area is a part of west and south west zones and Flysch zone of east of Iran. Ten representative pedons on different geomorphic units including hill, alluvil-colluvial fan, alluvial plain, and lowland were selected, sampled, and described. Routine physicochemical analyses, clay mineralogy, and micromorphological observations performed on soil samples. Soil pH, texture, electrical conductivity, calcium carbonate, Na, Ca, Mg, cation exchangeable capacity and gypsum were identified. Eight samples were selected for clay mineralogy investigations. Four slides including Mg saturated, Mg saturated treated with ethylene glycol, K saturated, and K saturated heated up to 550 oC were analyzed. A Brucker X-Ray diffractometer at 40 kV and 30 mA was used for XRD analyses. Undisturbed soil samples from some representative pedons were selected for micromorphological observations. A vestapol resin with stearic acid and cobalt as hardener was used for soil impregnation. A Lite petrographic microscope was used for micromorphology investigations.
Results and Discussion: The results of the present study indicated that the soils with more evolution were located on the geomorphic surfaces of the lowland and alluvial plain and the soils with lower development on the hill and alluvil-colluvial fan. The most important pedogenic processes of the soils were the eluviation of salt, gypsum, calcium carbonate as well as clay, and the formation of calcic, gypsic, petrogypsic and natric horizons. The soils of the region were classified using ST as Aridisols with three suborders of Argids, Calcids and Gypsids and classified according to the WRB as three soil reference groups of Solonetz, Gypsisols and Calcisolos. A new subgroup of Calcic Natrigypsids is suggested for inclusion to ST for the soils with aridic soil moisture regime and three horizons of gypsic, calcic and natric. The WRB system, due to its flexibility in the use of principle and supplementary qualifiers, prepare a better qualification than ST for the soils of the region. According to mineralogical results, the observed minerals consisted of illite, palygorskite, chlorite, smectite, kaolinite, vermiculite and quartz. The highest amount of palygorskite was observed in the gypsic horizons of hill and alluvil-colluvial fan. By moving to the central part of the plain (lowland), the amount of palygorskite was greatly reduced and the amount of smectite was increased. Two origins of inheritance and transformation (illite and palygorskite) are suggested for the occurrence of smectite in the soils. Due to the lack of the conditions for the formation of kaolinite, illite and chlorite, these minerals are inherited from parent materials. SEM observations suggested a pedogenic pathway for the occurrence of large amounts of palygorskite in the soils of the region. Calcareous and gypsiferous media seems to prepare a favorite environment for the pedogenic formation and stabilizing of this mineral in the studied soils. Coating and infilling of gypsum and calcite crystals in voids and channels, clay coating along chanels as well as Fe and Mn oxide nodules were among the common pedofeatures observed in the thin sections of the studied soils. Occurrence of variable habits of gypsum crystals in different geomorphic surfaces suggested a dynamic soil environment. Larger lenticular gypsum crystals were found in the soils with lighter texture located on more stable geomorphic surfaces.
Conclusion: Different geomorphic situations in the region affected the development and evolution, physicochemical properties, clay mineralogy, micromorphology and soil classification and caused the differences in these characteristics in the Faryab region.
Research Article
Saleh Sanjari; M.H. Farpoor
Abstract
Introduction: Soil studies have been used as complementary data in archaeological investigations. Review and acceptance of papers focusing on the use of micromorphology in archaeology were discussed and agreed in the 12th International Micromorphology Meeting in Turkey (8). Morphology, physicochemical, ...
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Introduction: Soil studies have been used as complementary data in archaeological investigations. Review and acceptance of papers focusing on the use of micromorphology in archaeology were discussed and agreed in the 12th International Micromorphology Meeting in Turkey (8). Morphology, physicochemical, clay mineralogy, and micromorphology investigations may provide invaluable data about the way ancient people used to live, the source of soil that was used for pottery and architecture, the reason of degradation or existence of monuments, and the suitable soil for the restoration of monuments. On the other hand, the restoration of our ancestor's monuments could be better performed if soil data and micromorphology techniques are used.
Materials and Methods: The present research was conducted to study the ancient and restored sections of Konar Sandal historical (5000 YBP) citadel, South Jiroft, Iran. The area under study located 30 km south of Jiroft in the Halilrud cultural area. Samples were collected from both ancient (3 samples) and restores (1 sample) sections of the citadel. Representative samples (3 from the ancient and the other from the restored sections) were also collected for clay mineralogy and micromorphology (undisturbed samples) investigations after physicochemical analysis performed on all samples. Routine physicochemical analysis performed on the air-dried samples that were passed through a 2 mm sieve.
Results and Discussion: Results of the study showed that the clay percentage of the ancient section was rough twice the restored section. On the other hand, soluble salts were about 3 times higher in the restored section than the ancient section. High salinity and solubility of salts caused restored sections to have lower resistance to environmental variations of the recent years. It seems that saline and gypsiferous soils close to the citadel were used for the restoration of Konar Sandal citadel. However, no gypsum was found in the thin section of the ancient section. Besides, Na monovalent cation plays an important role in the dispersion of soil particles compared to divalent Ca cation. Results of this study showed that soil with low clay content and high salinity was used for restoration recently. On the other hand, soils for construction of ancient sections with higher clay and lower salinity (compared to restored sections) were probably transferred from another area by our ancestors. Besides, pottery pieces to provide more stickiness and charcoal for more resistance to environmental variations were also used to construct the raw bricks in the old (5000 YBP) monument.
Illite, chlorite, smectite, and kaolinite clay minerals were found in the samples from the ancient section (Fig. 3). Palygorskite, quartz and trace amounts of sepiolite were only found in the restored sections together with the previously mentioned clay minerals (Fig. 4). The absence of palygorskite in the ancient samples may prove the presence of paleoclimate with more available humidity in the area because palygorskite is unstable in humid environments and transforms to smectite. It seems that palygorskite has a pedogenic origin in the area.
Micromorphological observations showed that the organic matter in the groundmass of the ancient samples (Fig. 6 a, b) is the reason for stability in this section. The same conclusion was also reported for samples of Bam citadel by Farpoor (4). Lenticular and interlocked plates of gypsum were found in the restored section (Figs. 6 c, and 7 a, b). Gypsum crystals were not observed in the thin sections of ancient samples. Calcium carbonate nodules were also observed in the ancient section (Fig. 7c). It seems that additives such as pottery pieces together with calcium carbonate have probably increased the stability of raw bricks through time.
Conclusion: Physicochemical properties showed more salinity in the restored compared to ancient sections and micromorphology showed gypsum crystals only in the restored samples. Besides, clay content and organic matter in the ancient section are about twice the restored section. Meanwhile, pottery pieces and charcoal were also found in the ancient section. These seem to be a reason for higher stability of ancient sections against environmental variations compared to restores sections with low clay content and high gypsum and more soluble salts that were degraded in 5 years. Illite, chlorite, kaolinite, and smectite clay minerals were investigated in both sections, but palygorskite and quarts were only found in the restored section. Results of the study clearly showed that soil data might be used as a helpful technique in archaeology studies and projects.
Research Article
mahboobeh farzandi; Seyed Hossein Sanaeinejad; Bijan Ghahraman; Majid Sarmad
Abstract
Introduction: Temperature and precipitation are two of the main variables in meteorology and climatology. These are basic inputs in water resource management. The length of the statistical period plays a pivotal role in the accurate analysis of these variables. Observation data at Iran's first ...
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Introduction: Temperature and precipitation are two of the main variables in meteorology and climatology. These are basic inputs in water resource management. The length of the statistical period plays a pivotal role in the accurate analysis of these variables. Observation data at Iran's first synoptic station from 1330 (1951) is available at the Iranian Meteorological Organization website The historical monthly precipitation and temperature of five stations in Iran is available since 1880 with missing data. These data measured by the Embassy of the United States and Britain from the Qajar period and recorded in World Weather records books. These synoptic stations include Mashhad, Isfahan, Tehran, Bushehr, and Jask. The monthly missing data were predominantly recorded during World War II (1941-1949). Unfortunately, these data have missing. Therefore, the accuracy of simulating these variables is very important. The current research aimed to predict the missing values of monthly temperature and precipitation in Mashhad station. The stations in the neighboring countries were selected due to the distance to Mashhad, relationship, and completeness of data since 1880, as the predictive variables. Monthly precipitation of Ashgabat from Tajikistan and Sarakhs, Kooshkah, Bayram Ali, Kerki and Repetek from Turkmenistan were selected as an independent variable in the making of Missing Rainfall in Mashhad. Also, the temperature of Ashgabat, Bayram Ali, Gudan, Sarakhs, and Tajan were selected to restore the monthly temperature of the Mashhad station. This research has fitted ten multiple regression models to monthly rainfall of Mashhad station and has fitted 6 multiple regression to the monthly temperature of Mashhad. then the parameters of these patterns are optimized by genetic and Ant Colony algorithm. Also, the Artificial Neural Network (MLP) model and Support vector regression have been selected and implemented in order to simulate monthly precipitation and temperature data of Mashhad.
Materials and Methods: In statistical modeling, regression analysis is a set of statistical processes for estimating the relationships among variables. It includes many techniques for modeling and analyzing several variables when the focus is on the relationship between a dependent variable and one or more independent variables (or 'predictors'). Genetic algorithm (GA) is a metaheuristic inspired by the process of natural selection that belongs to the larger class of evolutionary algorithms (EA). Genetic algorithms are commonly used to generate high-quality solutions to optimization and search problems by relying on bio-inspired operators such as mutation, crossover, and selection. Ant colony optimization algorithm (ACO) is a probabilistic technique for solving computational problems which can be reduced to finding good paths through graphs. This algorithm is a member of the ant colony algorithms family, in swarm intelligence methods, and it constitutes some metaheuristic optimizations. Artificial neural networks are one of the main tools used in machine learning. As the “neural” part of their name suggests, they are brain-inspired systems which are intended to replicate the way that we humans learn. Neural networks consist of input and output layers, as well as (in most cases) a hidden layer consisting of units that transform the input into something that the output layer can use. They are excellent tools for finding patterns which are far too complex or numerous for a human programmer to extract and teach the machine to recognize. In machine learning, support vector machines (SVMs, also support vector networks) are supervised learning models with associated learning algorithms that analyze data used for classification and regression analysis. Given a set of training examples, each marked as belonging to one or the other of two categories, an SVM training algorithm builds a model that assigns new examples to one category or the other, making it a non-probabilistic binary linear classifier (although methods such as Platt scaling exist to use SVM in a probabilistic classification setting).
Results and Discussion: At the first stage, several multiple regressions were fitted to monthly precipitation (with coefficients ranging from 0.63 to 0.81) and six patterns for monthly temperature (0.986-0.993). Afterward, GA and ACO were applied to improve the accuracy of the selected regression models by optimizing their parameters. At the next stage, ANN and SVR were used to estimate the monthly missing values separately. Finally, the results of the previous stages were compared using the root mean square error (RMSE), and the optimal models were applied to determine the missing values of monthly temperature and precipitation of Mashhad. The results showed that the Genetic Algorithm and Ant Colony increase the accuracy of the estimation of missing rainfall data significantly more than the previous methods. The lowest error criterion (RMSE) between regression patterns is 9.8 millimeters. By genetic algorithm, this criterion is reduced to 2.56 mm, and by ant colony algorithm to 2.559.
Conclusion: Comparison of the above methods in restoration temperature and precipitation shows that evolutionary methods (GA and ACO) are the best for estimating the missing monthly precipitation and machine learning methods (ANN and SVR) are the best to imputation missing data of monthly temperature.
