جستجوی مقالات مرتبط با کلیدواژه « قطره چکان » در نشریات گروه « آب و خاک »

Clogging of emitters is one of the main challenges for farmers using drip irrigation systems. Therefore, in the present study, solutions to reduce chemical clogging of emitters based on acid-washing methods and ultrasonic systems have been presented. The ultrasonic system, considered a type of green technology, has been proposed to mitigate emitter clogging in drip irrigation systems. In this regard, first, samples of emitters were selected from the chosen fields, and then they were grouped by measuring their discharge. Based on the measured discharge compared to the nominal discharge, the emitters were classified into five categories in terms of clogging: category 1 with 100% clogging, category 2 with 75-100% clogging, category 3 with 50-75% clogging, category 4 with 25-50% clogging, and category 5 with 0-25% clogging. Four treatments were applied for each category: (1) acid washing at pH = 3, (2) acid washing at pH = 5, (3) ultrasonic bath cleaning, and (4) ultrasonic-acid washing. A reduction in clogging of zero-grade emitters, when placed in an ultrasonic bath for 15 minutes, was approximately 45%. Based on the analysis of variance, it can be observed that, with a P-value of 0.1 and an F-value of 2.81, the use of the ultrasonic method significantly affects emitter clogging at a 90% confidence level. A comparison of clogging reduction after washing shows the significant superiority of the ultrasonic method over acid washing. The results revealed that the ultrasonic washing method only reduced physical clogging, while the acid washing method reduced chemical clogging. The ultrasonic system is an environmentally friendly and green technology proposed to reduce emitter clogging in drip irrigation systems.

Water shortage and the need for its optimal use in arid and semi-arid regions, including Iran, has led water officials and farmers to use modern irrigation systems, such as drip irrigation with the aim of making optimal use of water resources. Drip irrigation has been welcomed in most parts of the world due to its high efficiency and the possibility of irrigation in different environmental conditions. The most important reason for the superiority of drip irrigation over other irrigation methods is the controllable amount of water for each plant. Drip irrigation is a method in which water is poured out of the net at low pressure through an orifice or device called an emitter and dripped into the bottom of the plant. This irrigation system, like other methods, requires accurate knowledge of the parameters affecting it to achieve the desired efficiency. One of the most important parameters for the irrigation system is the distribution of moisture in the soil and in fact the shape of the moist bulb. Therefore, knowledge of how to distribute water in the soil is essential for the proper design and management of subsurface drip irrigation systems. Since testing is very difficult and time consuming to detect the shape of moisture distribution in the soil, the use of numerical and analytical simulation can be an effective and efficient way to design these systems.

In order to determine the progress of the moisture front in drip irrigation, first the soil texture type and physical properties of the soil were determined. It should be noted that the emitter flow rate was measured and adjusted in volume at the beginning of the test to minimize the difference between the emitter flows along the three side tubes. Evaluation experiments were performed with three outflows of 2, 4 and 6 liters per hour. With the start of the system, the progress of the moisture front at different times was measured by digging a trench using a scale. Numerical simulation of moisture front progress was performed using HYDRUS model based on Richard equation and analytical simulation was performed using Moment Analysis. HYDRUS software was used to numerically simulate the progress of the moisture front. The simulation range was considered to be 100 cm by 100 cm on the two-dimensional plane. In these simulations, 3956 nodes are used to represent the entire simulation range and also, relevant equations were used to calculate the two-dimensional spatial Moment of the wetting pattern.

The simulations show that the initial volumetric moisture content is 0.11 and the saturation volumetric moisture content is 0.380 and the water dispersion rate increases over time on the x and z axes. With increasing flow, the maximum dispersion is in the x-axis, which occurs in flow of 6 liters per hour. The result for flow of 6 liters per hour based on the data used is slightly higher than the desired value. The reason why the value of M00 in the flow rate of 6 liters per hour is higher than expected, is that in the simulation flow rate of 6 liters per hour change in the size of the inlet diameter and the amount of flux changes the amount of water entering the soil and moistens a large volume of soil. Due to the different amount of moisture applied to the area at different times, the value of z_c,σ_x^2,σ_z^2 is different and has caused a change in the size of the oval in different flows. The increase in the size of the ovals indicates the high dispersion of water in that area. The results showed that the Moment analysis was able to express the position of the center of mass of water distributed in the soil with correlation coefficient of 0.986 in linear mode and 0.982 in logarithmic mode. By comparing the values of diameter and depth obtained from the HYDRUS and the drawn ovals, it can be concluded that both methods provide close results. The accuracy of the Moment analysis method in simulating different types of moisture patterns resulting from drip irrigation under different flows with the use of different volumes of water is similar to the HYDRUS model and therefore it is possible to use this feature to predict the pattern of moisture from a certain flow using a specific volume of water.

In this study, the accuracy of Moment analysis in simulating various moisture patterns resulting from drip irrigation under different flows with the use of different volumes of water was investigated and the possibility of using this feature to predict the pattern of moisture from a given flow using a specific volume of water checked. In order to investigate the Moment of the amount of water distributed in the soil by subsurface drip irrigation, simulation was performed by two-dimensional HYDRUS software for three discharges of 2, 4 and 6 liters per hour with an inlet water volume of 12 liters. Then, using the results of simulation of moisture distribution range by a programming language including MATLAB software, and by calculating the Moments, it was determined that the Moments are able to express the position of the center of mass of water distributed in the soil and how it is distributed relative to x and z axes. The increase in the size of the ovals indicates that more water is distributed in that area. Comparing the diameters and depths of the moisture front between the simulated HYDRUS model and the Moment analysis model, it was found that the Moment analysis is an efficient way to study the distribution of water moisture by drip irrigation and this method can be used as an alternative input to estimate parameters.

Performance-importance analysis examines the gap between the importance (ideal status) of the emitter's role on the efficiency of drip irrigation systems and the performance (status) of the factors affecting it. For this purpose, the stakeholder's perspective was investigated by means of a questionnaire. The validity of the questionnaires was checked using Content Validity Index (CVI) and their reliability was confirmed by Cronbach's alpha in the two dimensions with the values of 0.83 (importance) and 0.86 (performance), respectively. The weighting method based on Shannon entropy was used to determine the importance of items, and in the case of performance, the significant effect of each items (current status) on the efficiency of systems was surveyed statistically. Moreover, the difference between the importance and performance of each item is also was performed through t- test. According to the results, the most statistically significant difference between the mean of importance and performance of items was observed in items 4, 6, and 12, with negative values of 3.27, 3.19, and 2.85, respectively. This result indicates that there is a significant gap between the desirable stakeholder's perspective (importance) and current status (performance) of these items. Emitters clogging (item 12) was the most important factor in the efficiency of the drip irrigation system. Furthermore, training, advice and guidance of stakeholder before and after the implementation of drip irrigation systems (items 6 and 7) are important and affect the efficiency of the systems, whereas, there was no such thing in practice. Therefore, they need focus and attention.

Water distribution and soil moisture changes are necessary to design the irrigation system that are costly and time consumer. This study aimed to estimate the performance of HYDRUS-1D model to estimate the distribution of soil moisture in the surface and subsurface drip irrigated in wheat cultivation using ET-HS model to estimate water demand in the arid region. A field experiment was conducted with three depth of emitter installation (0-15 and 30 cm) and moisture measurement at six soil depths (10 to 60 cm) with four repetitions for two consecutive years in arid and semi-arid areas of Isfahan. For this reason, Soil moisture was measured using soil moisture detector device (Diviner 2000) every day. Simulated and field data were compared on the basis of statistical indicators. The results showed that except in 0-10 cm with coefficient of determination (R2 = 0.74), other layers have high R2 value and best fit was at a depth of 10-20 (R2=0.93). The root mean square error (RMSE) index values were low except in the surface layer (0-10) with 0 and 30 cm depth of emitter. Highest and lowest values of coefficient of residual mass (CRM) was 0.008 and -0.0046, respectively. Based on aforementioned results of the evaluation, the model can be used for optimal management of irrigation in arid and semi-arid.

In this study, a practical procedure was proposed for hydraulic analysis of flow in drip line lateral in the drip irrigation system to determine the major and minor losses of the driplines. In this method, the friction losses between the drippers and local head losses of the drippers were calculated step-by-step and the total pressure losses of the lateral were determined by summation of the head losses. To determine the minor losses of the emitters, the power relationship between the pipe discharge and the measured head losses related to simple and drip line pipes was determined by the nonlinear regression method. Then, the difference of the obtained head losses of these relationships in different discharges was calculated. Then, the power relationship between these results and discharge was determined by using nonlinear regression again. Also, Hazen–Williams equation and Darcy-Weisbach relationship used to determine the friction head losses. The friction coefficient (f) determined using Altshul, Blasius, and Moody diagram. Thus, four different methods of combining minor and friction head losses equations were obtained and evaluated using RE, MAE and RMAE indices. Experiments were conducted on three 60-meter samples of drip lines with emitter spacing of 0.20, 0.40 and 0.50 m and a simple sample with 16 mm diameter at 50, 100, 150, and 200 kPa pressures. The results indicated that the Darcy-Weisbach relationship based on the Blasius relationship was more accurate than the other methods. Also, the performance of the proposed experimental relationships were acceptable to estimate the local head losses. Therefore, the proposed method is recommended to calculate the head losses in the dripline laterals.

Sugarcane fields of the southwest of Iran have heavy soil texture, high temperatures, hot and dry wind flow at spring and summer seasons. The electrical conductivity of irrigation water was considered about 1.1 dS.m-1, in basic designs of this irrigation method. In addition to sugarcane production, sugar is a fundamental good in the economic section of Iran. It has multiple use in food, medical and chemical industry, production of by-products such as feedstuffs, yeast and alcohol, wood and paper. Sugarcane requires lots of water during the growing period and sensitive to water stress and is not compatible with long duration of flooding. If groundwater rises and covers the root zone, crop yield decreases due to root rot. Significant benefits are identified in terms of increased yield, improved crop quality, reduction in applied water, and reduced agronomic costs for weed control, fertilization, and tillage. Improved water management is crucial for a sustainable future, and SDI will be one tool that is available to improve water productivity. The main advantages of SDI are related to water savings because water is applied directly to the crop’s root zone, which prevents losses due to direct evaporation from the soil and deep drainage, and, if properly managed, SDI allows for the maintenance of appropriate levels of soil moisture. Due to the water crisis in Iran, this study aimed to reduce the volume of consumed water and water productivity for sugarcane and sugar yield by managing water consumption using drip irrigation for the first time in the cultivation of sugarcane.

According to recent droughts and severe water crises in Iran, subsurface drip irrigation was implemented in sugarcane for the first time. It seems that water consumed in subsurface drip irrigation is less than other methods. Therefore, its effect was investigated by 15, 20, and 30 cm depths and 75 cm space of subsurface emitters and comparison with control, on water productivity and sugarcane yield. An experiment based on randomized complete block design was carried out at the Sugarcane Research and Training Institute of Khuzestan in the South-West of Iran. After harvesting the plant field (start Ratoon), soil samples were collected at 0-30, 30-60, and 60-90 cm depths. In order to measure the bulk density of soil, samples were collected from the undistributed samples with sampler cylinders, and the texture was determined by the hydrometer method. To assess soil moisture percentage, pressure plate was used for determining content in field capacity (FC) and permanent wilting point (PWP) (the results were 25.1% and 12.9%, respectively). Emitters were pressure controlled emitter type, anti-siphon and the pressure at the pump station was 4.3 bar, and emitters with a flow 2.2 liter-1 and the depth of emitters pipes were 15, 20, and 30 cm from the surface soil. Depending on irrigation frequencies and irrigation water acidity, acid was injected into the irrigation water to prevent clogging of the emitters. After a specified time, it was discharged from the network. Regarding the presence of algae in irrigation water, chlorine gas was used in acid filtration before irrigation in field capacity. Finally, the average quantity and quality functions and Water Productivity in subsurface drip irrigation were compared with compression irrigation. For data fitting and curves, EXCEL software was used, and SAS statistical software was used for statistical analysis. Also, to investigate the salinity distribution in drip irrigation, the mean soil samples were used during the sampling period. The figures were drawn using 8 Surfer software in two dimensions. In drawing the shapes, Craig’s introspection was used.

High evaporation, air temperature, and relatively low quality of irrigation water are the most important limiting factors for sugarcane irrigation in Khuzestan. It seems that according to the research records, the irrigation of subsurface drops with proper management is successful. Therefore, for this purpose, the effect of planting depth of 15, 20, and 30 and a distance of 75 cm drops and to compare with the regular irrigation of sugarcane lands as control (control), on water productivity and sugarcane yield complete random blocks was applied. The results of the analysis of variance of quantitative traits showed significant effects of the planting depth of droplets, in terms of yield at the level of one percent and in terms of stem height traits, number of stems per hectare, and water efficiency per sugarcane and produced sugar, at the level of five percent. According to the results of qualitative traits, the effect of treatment of droplet implant depth in all traits was non-significant. At a depth of 20 cm, the highest efficiency of water production for sugarcane and sugar production were 1.6 and 0.73 kg / m3, respectively. The lowest water productivity for sugarcane and sugar produced in the control treatment was 4.2 and 0.51 kg / m3, respectively. As a result, water productivity in the treatment of selected index (planting depth of 20 cm) per sugarcane and produced sugar has resulted in an increase of more than 30% in water productivity compared to the usual irrigation of fields (control). The results of salinity distribution around the droplets also showed that under the conditions of irrigation of subsurface droplets with salt water, the lowest salinity values ​​were always seen as a range around the droplets. With increasing distance from the droplets, the salinity increased. More salts The drops are concentrated in the streams on both sides of the drops, The highest salinity occurred at the bottom of the furrow, and the lowest salinity was found on the ridge, where the drip pipe was planted and on either side of which there were two rows of reeds.

Subsurface drip irrigation is one of the most optimal irrigation methods that are almost unknown to sugarcane in the executive, research, and academic sectors, and has been implemented for the first time in sugarcane cultivation in Iran. Given the recent droughts and the crisis and water scarcity, and the importance of environmental issues, it will be invaluable to investigate further and apply them. In general, in this study, using a flow rate of 2.2 lit/hr and a space of 75 cm and an installation depth of 20 cm droplets, the highest quantitative and qualitative functions and the highest water productivity per sugar cane. And the sugar produced. Also, regardless of any deepening treatment, the drip irrigation system, compared to the conventional irrigation system, reduced water consumption by about 20% and water yield by 26% per sugarcane and sugar produced. According to the results and considering the uniformity of moisture distribution, soil surface salinity, lack of runoff, protection of the discharge pipe, removal of surface evaporation and sugarcane root development, depth of 20 cm, application of the discharge pipe with a distance of 75 cm drops on the hose with a flow rate of 2.2 lit/hr are recommended. Also, although the distribution of moisture onions is provided up to a distance of 80 cm, a shorter distance between the droplets, such as 60 cm with the above flow, needs further investigation.

Due to the increasing number of small crops, the system of irrigation without a pump can be an economical way. Therefore, in this research, the effects of the type of droplet and the height of water supply system utilization on the characteristics of water distribution (discharge, dispersion uniformity coefficient (CU) and coefficients of variation of discharge) were investigated. In this research, the pressure functions of 1, 2, 3 and 4 meters and three irrigation repeats were investigated; also, the discharge characteristics of jet pots of 2 and 8 nozzles, easy dripper and netafim were addressed. The results indicated that at 1 m pressure, drippers of pots of 2 and 8 nozzles with the uniformity coefficients of distribution were equal to 89.39 and 99.30%, and the discharge rate was 3.60 and 3.62 liters per hour at a pressure of 2 m. An easy-drain drip with a discharge rate of 3.85 L / h and a uniform distribution of 99.44%, at a height of 3 and 4 m, the droplets of the netafim with an outlet discharge were 3.87 and 3.97 liters per hour and the uniformity coefficients of 99.32 and 99.47 percent had the best broadcast conditions. According to these significant differences (P <0.05), it can be concluded that at pressures less than 2 m of jar droplets and at more than 3 m, netafim and Easy Dipper types could  have better leakage due to pressure regulators. In general, each of the four types of emitters produced a uniform dispersion and the optimum discharge at different pressures.

This study was conducted to measure water flow and root uptake under the soil in a 2 m × 2 m plot around an apple tree 15 years old under subsurface drip irrigation in Miandoab region and simulated by different scenarios in HYDRUS-2D software. The emitters were installed at a depth of 30 cm and a distance of 1 m from the trunk of tree. The soil water content was measured daily using a TDR device for 4 months. In order to calibrate of root water uptake equations, samples from root and soil were collected from different parts of root development zone. The results showed that the highest and lowest amount of root water uptake were 0.129 and 0.024 cm3.cm-3, respectively, that occurred in the coordinates (radial, deep), (60 cm, 50 cm) and (150 cm, 75 cm) from the tree trunk, respectively. Approximately 81% of root water uptake was at a depth of 0-50 cm. The amounts of RMSE (0.0141- 0.0193), showed that, the HYDRUS-2D software can have an appropriate estimate from soil water content in subsurface drip irrigation. Comparison of different scenarios simulated in HYDRUS-2D with the results of field measurements showed that by reducing the emitter discharge by 2 lit/h and increasing the irrigation duration (in the constant amount of water used), the root water uptake increased by 5.08% and deep penetration decreased by 2.18% compared to actual condition.

High temperature and evaporation and low quality irrigation water are the most limiting factors for irrigation of sugarcane in Khuzestan. Subsurface drip irrigation can be successful with proper management. Therefore, this study was conducted to examine the effect of subsurface drip irrigation on Water Productivity and sugarcane yield. Two factors consist of installation depth (15, 20, 30 cm) and emitters spaces (50, 60, 75 cm) were applied in a factorial experiment with randomized complete block design. The results of variance analysis of quantity characteristic indicated that there were significant differences between treatments in terms of installation depths, emitter space and their interactions at 1% probability level. Also the results of quality characteristics showed a significant differences among the emitter's spaces at 1% probability level. Investigation of water productivity index showed that there were significant differences among the emitters space for sugarcane and sugar production at 1% probability level. But there was no significant differences among emitter depths and depth-space interactions. The maximum quantity yield occurred in drip laterals with 50 cm emitter space and 20 cm installation depth. The highest quality yield was seen in laterals with 50 and 60 cm emitter spaces and 15 and 20 cm installation depths. The highest water productivity for sugarcane and sugar production was obtained 7.18 and 0.87 kg /m3 in laterals with emitter space of 60 cm and installation depth of 20 cm. Also the least water productivity for sugarcane and sugar production was 5.17 and 0.61 kg/m3 in laterals with emitter space of 75 cm and installation depth of 20 cm. Finally, according to the obtained results and considering other conditions, laterals with 50 cm emitter space and 20 cm installation depth are suggested for irrigation of sugarcane fields.

The emitter is a device used to dissipate pressure and to discharge water at a constant rate when pressurized water flows through its narrow and long path channels, hence emitter is the key component of the drip irrigation system. On the other hand, production of a suitable emitter is expensive and time–consuming. The use of computational fluid dynamics (CFD) can be a useful tool for reducing the time and cost of manufacturing of drip emitters. For this purpose, in present study three different types of drip emitters (with different channel geometry) were chosen and their structural parameters are determined using SEM. Rate of discharge of emitters were simulated by 4 turbulence models (standard k- ε ¡ RNG K-ε¡ K-ε Realizable¡ standard k-ω) and Laminar model compared with experimental discharge. Results showed that on the whole there was generally good agreement between the experimental results and those obtained by different turbulent and laminar models. But among the studied models, results of standard k- ω and standard k- ε had the best and the worst agreement with experimental results, respectively. So that, the mean NRMSE of three emitters for standard k-ε and standard k-ω models was determined 7.57 and 3.56 percent, respectively. As well as with regards to low Reynolds number, the laminar model also presented good results.

Clogging of emitters is one of the main problems in subsurface drip irrigation. The objective of this study was investigation of effect of Geocomposite on wetting pattern in subsurface irrigation system. This research was conducted in lysimeters located at Shahrekord University research field. The study was conducted as a factorial experiment based on a completely randomized design with 10 treatments and three replications of three factors. The first factor of experiment was geocomposite shape with the same area on two levels (shape square with dimensions (4 × 4) square centimeters and rectangular with dimensions (2 × 8) square centimeters), the second factor was combination of geocomposite material on two levels (two layers of geotextile on both sides of Geonet and The second level, a layer of geomembrane and a layer of geotextile on both sides of geonet), the third factor of placement in the soil at on two position (horizontal and vertical) and emitter with envelopment (in two position horizontal and vertical) were used as control. The ground wet and wet the maximum of soil depth profiles were measured. The results was showed that geocomposite of shape square with dimensions (4 × 4) square centimeters for a layer of geomembrane and a layer of geotextile on both sides and how to align horizontally in the soil wet ground level by lowering the 21.55 percent and increased 17.1 percent wet the soil deep profile compared to control (emitter with envelopment horizontally in the soil) is the most effective and best conditions on wetting profiles.

Due to limited water resources, there is too much emphasis on the efficient use of present water resources and the use of waste water and saline and brackish water for irrigation. Therefore, for having a successful agriculture, it is necessary to the process come under the control of salinity. Magnetized water can be used for reclamation of water and soil. In this study the soil moisture and soil salinity around the emitter at different stage of irrigation have been investigated. The treatments including two treatments of irrigation water (magnetized water and non-magnetized water) as main treatments and three level of salinity including well water, saline waters 5 and 10 dS/m were a minor factor. Field experiment was performed as split split plot in randomized complete block with three replications. The results showed that irrigation with magnetized water as compared to normal irrigation, soil moisture increased in different distances from the emitter. Also, irrigation with magnetized water caused reduction of 31 percent of soil electrical conductivity than normal irrigation. The magnetized irrigation saving water use and solved the soil salinity problem, recommended for use in agriculture.

One of the potential advantages of drip irrigation is allowing the use of fertilizer and poison with irrigation water. In this study, the effect of fertilizers on clogging dripper and drip irrigation system performance has been investigated. This study in a randomized block design framework was done that its factors were three treatments of fertilizer (ammonium phosphate) includes treatment F0 (control), and a F1 with concentrations of 5 g/l, respectively, and three dropper treatment (the in line long path and two outline long path). Dropper with codes A, B and C were named. In order to investigating dropper clogging, reduce discharge rate, efficiency of uniform distribution, Kristiansen uniformity coefficient and coefficient of discharge variation was calculated. After test period the percentage of reduce discharge for droppers was obtained 19.9, 20.78, and 11 percent for treatment F0 (control) respectively, and 26.48, 26.49 and 16.65 percent for treatment F1, respectively. The results were shown increasing concentration of irrigation fertilizer caused increasing dropper clogging and have a significant effect on Changes in discharge.

An appropriate water resources management and planning is necessary due to the scarcity of water resources and rapidly growing world population. In this regard, selecting appropriate methods for irrigation is one of the most important issues. Drip irrigation is a recent advanced irrigation method in which fertilizers can be efficiently applied along with irrigation water. Drip fertigation, however, can potentially cause clogging of emitters. Various factors such as clogging increase manufactures’ coefficient of variation and water temperature and pressure changes could alter emitter discharge and water distribution uniformity. The aim of this study is to evaluate the effect of fertigation on clogging of emitters and the performance of drip irrigation systems. This study was performed as a laboratory experiment at the University of Zabol. The experiment was done in the form of factorial in a completely randomized design with three replications in the hydraulics laboratory, the University of Zabol. The first factor was fertilizer type including: F0 (control), F1 (ammonium nitrate) and F2 (urea) and the second factor was the emitter types including one-nozzle on line (A), six-nozzles in line (B) and eight-nozzles on line (C). The tap water was used for irrigation. The system included 9 laterals, 3 m each with 18 emitters on each lateral. Fertilizer solution with known concentrations of 0.08 grams per liter was entered into the system from a plastic tank. Fertilizer tank was covered to avoid water evaporation even in a small amount. The experiment lasted for 60 days with 12 operating hours per day. The emitter discharge was measured every three days at the end of day. In order to evaluate the degree of emitter clogging, the percentages of discharge reduction (Qt), Christiansen’s coefficient of uniformity (CU), distribution uniformity (DU) and discharge coefficient of variations (Vm) were calculated as follows: where qa, qm and qt are the average, primary and secondary emitter discharges (L/hrs), respectively, qi is the individual emitter discharge (L/hrs), Sm is the standard deviation of discharge (L/hrs) and n is the number of measurements. The results indicated that both fertilizer and emitter type have significant effect on reduction of emitter discharge and distribution uniformity as well as on increase of emitter coefficient of variation. The Duncan test for comparing means showed that the A type emitters had the highest clogging while the B type emitters had the lowest clogging. The percentages of discharge reduction for emitters A, B and C were about 18, 24 and 22, respectively, for treatment F0 (control); 24, 39 and 30 for treatment F1; and 34, 44 and 32 for treatment F2. The results indicated that the emitter clogging increases with altering fertilizer from F0 to F2. F2 (urea fertilizer) had the worse effect on emitter clogging than F1 (ammonium nitrate fertilizer) which could be due to more nitrate produced by urea fertilizer. Also, the results showed that the emitter clogging and discharge coefficient of variation are increased by increasing the elapsed time. Urea and ammonium nitrate fertilizers are hydrolyzed in water and partly converted to nitrate, which is consumed by algae and other microorganisms causing slime accumulation. Bacterial slimes can be a direct cause of clogging for emitters. According to the results, both fertilizer and emitter types may significantly change the hydraulic properties of emitters. The smallest clogging belonged to emitter of type A when fertilizer F0 was applied as it results in discharge reduction of 18.44%. The largest clogging belonged to emitter of type B when fertilizer F2 was applied (discharge reduction was about 44%). In general, it could be said that fertigation may influence emitter discharge depending on fertilizer treatments (e.g. fertilizer type and concentration), water properties and emitter type. The clogging problems must be attended more specifically as it may reduce farmers’ willingness for drip irrigation implementation and makes them do surface irrigation which may result in more water losses. This study showed that the quality of water used in drip fertigation increases the clogging made by fertilizer application. So, the quality of irrigation water should be investigated every few days. The use of nitrogen fertilizer may cause biological clogging of emitters, so when such fertilizer are used, the type of emitter should be considered.

Proper management of saline soils needs adequate information about the amount and salt distribution in the root zone. Irrigation of the factors that control the distribution of salt. This paper investigates salt distribution under two sources of dripper and bubbler. This study based on the evaporation of soil surface of a land without plant located at shahid chamran university، Ahwaz، Iran. Samples were taken from three distances 0، 20 and 40cm from the soil surface and 0-20، 20-40، 40-60 and 60-80 depths. The results showed that، the average salinity of bubbler were 12. 75 dS/m that less than drippers with 13. 64 salinity respectively. Among measured depth، the depth of 20 – 40 cm was known as the best working depths، the depth of 60-80 cm had the most salt with salinity of 15. 76 dS/m. depth of 0-20 cm (with the average salinity of 12. 53 dS/m includes more salinity than the depth of 20-40 with the average salinity of 11. 48 dS/m. Soil salinity decreased by time pass and irrigation until the last irrigation، soil salinity under the dripper reached) with salinity of 3. 62 dS/ m) to 1/15 and under the bubblersalinity of 3. 99 dS/ m) to 1/14 of the initial amount.

Designing and scheduling of drip irrigation systems are often done without enough information about water distribution in the soil. Due to tillage operations and crop production practices, agricultural soils can be considered as two layered soils with different bulk densities. The top soil layer has a lighter texture than the sub soil layer. In this research, the development of the wetting front and moisture distribution in a two-layered soil were investigated. The filed experiments were performed in the Tabriz University’s Research Farms, in order to determine the characteristics of the wetting patterns of drip irrigation under linear sources in a two layered soil. To study the effects of application duration and volume of water applied on the horizontal and vertical dimensions of wetting pattern, the experiments were conducted with four durations of 1, 3, 5, and 7 hours. The results showed that increasing the application duration increased the horizontal and vertical dimensions of the wetting patterns. But, after 5 hours, the application duration had no significant effect on the wetting pattern dimensions. In the subsoil layer, due to its heavy texture, vertical movement of the pattern was very slow and increase in the application duration more than 5 hours only caused increase in the volumetric moisture of the wetted soil. Using HYDRUS-2D model, the field experiments were simulated under the same conditions, too. The comparisons between model simulations and experimental results showed satisfactory agreement. According to the results, it can be demonstrated that the accuracy of HYDRUS- 2D in a two layered soil decreased when the wetting pattern reached the 2nd layer.

Many numerical and analytical models have been developed for estimation of soil water distribution in order to increase water use efficiency in drip irrigation. Accurate solution of well-known soil water equation، Richard’s equation، in these models cause more accurate estimation of soil wetting front. The purpose of this study was to evaluate finite difference and finite element methods to numerical solution of Richard’s equation for simulating soil water flow around dripper via comparing HYDRUS-2D and SEEP/W numerical models. Experiments were carried out to collect required data to investigate the advance of moisture front inside a Plexiglas box filled with a silt loam soil in central laboratory of water researches in University of Tehran. Wetting front advance at different time intervals were plotted on the transparent Plexiglas box walls. The wetting front around the emitters، for pressures 1. 5 and 2. 2 meters (equivalent to 4. 5 and 6. 3 liters per hour، respectively)، were measured. Comparison of two simulation models، HYDRUS-2DandSEEP/W، showed that HYDRUS-2D model (finite difference solution method) with higher determination coefficient and lower root mean square error coefficient had better performance to simulate wetted area dimensions for both surface and subsurface drip irrigation.

Drip irrigation is a new method of irrigation that is rapidly growing in different countries. The emitters are the most important parts of a drip irrigation system. Many factors such as physical، chemical and biological clogging، pressure، water temperature affect the emitter´s uniformity of water emission. In this study، to investigate pressure effect on the hydraulic performance of emitters، 7 kinds of compensating emitters in the market were selected and studied in laboratory conditions. For this purpose، a drip irrigation system was designed in irrigation laboratory in faculty of water sciences engineering، Shahid Charm University، Ahwaz. Average flow of emitters، Manufacturer´s coefficient of variation of emitter (CV)، emission uniformity (EU)، Christiansen coefficient of uniformity (CU) and Flow Variations for all types of emitters at pressures of 5، 10، 15 and 20 meters were calculated and compared. Also، in order to compare the pressure compensating capacity، for every emitter the equation of Flow- pressure was extracted. Results showed that the D-type emitter has the best hydraulic performance from among the emitters tested. Therefore، to achieve higher efficiency and also to use it on slopes and uneven lands this emitter is recommended as the best. However، performances of other emitters are also acceptable.

One of the potential advantages of drip irrigation is allowing the use of fertilizer and poison with irrigation water. In this study, the effect of fertilizers on clogging dripper and drip irrigation system performance has been investigated. This study in a randomized block design framework was done that its factors were three treatment of fertilizer (ammonium phosphate) includes treatment F0 (control), and two F1 and F2 treatments with concentrations of 5 g/l and 8 g/l, respectively, and three dropper treatment (the in line long path and two outline long path). Dropper with codes A, B and C were named. In order to investigating dropper clogging, reduce discharge rate, efficiency of uniform distribution, Kristiansen uniformity coefficient and coefficient of discharge variation was calculated. After test period the percentage of reduce discharge for droppers was obtained 19.9, 20.78, and 11 percent for treatment F0 (control) respectively, and 26.48, 26.49 and 16.65 percent for treatment F1, and 33.67, 33.06 and 18.59 percent for treatment F2, respectively. The results were shown increasing concentration of irrigation fertilizer caused increasing dropper clogging and have a significant effect on discharge variation.