drip irrigation

Identifying genotypes tolerant to deficit irrigation and introducing them to farmers and breeder is a suitable solution to improve the productivity of irrigation water. This study aims to evaluate 50 cucumber genotypes from the cucumber germplasm bank of University of Guilan in the greenhouse of the Faculty of Agricultural Sciences at University of Guilan under two irrigation levels: full irrigation and deficit irrigation (50% of full irrigation). The goal is to identify the best genotypes based on yield, irrigation water productivity, and economic productivity of irrigation water. These genotypes were selected for seed production and use in breeding programs. A drip irrigation system was used, and irrigation management was based on the water requirement of cucumbers inside the greenhouse. The cucumbers were harvested at commercial maturity, and yield, some yield component, irrigation water productivity, and economic productivity of irrigation water were determined. The results showed that irrigation significantly affected the number of fruits, irrigation water productivity, and economic productivity of irrigation water. The effects of genotype and the interaction between irrigation and genotype on fruit fresh weight, irrigation water productivity, and economic productivity of irrigation water were also significant. Based on the number of fruits per plant, fruit fresh weight yield, irrigation water productivity, and economic productivity of irrigation water, genotypes 42, 43, and 45 were identified as the best choices, while genotypes 13, 15, 16, and 18 were deemed inappropriate under the conditions of this study. Using the selected genotypes for cucumber seed production can simultaneously improve yield and irrigation water productivity, thereby enhancing the economic productivity of irrigation water.

Wheat is one of the most important strategic agricultural products. One of the most important policies of the country is to achieve self-sufficiency in wheat production. The relatively large area under cultivation of this crop has caused a large volume of water resources to be consumed for wheat production. One of the solutions to further increase water productivity in wheat production is to use the drip irrigation method (Tape). This study aimed to investigate the effect of planting arrangement and lateral spacing on wheat water productivity at the Jolghe-Rukh Agricultural and Natural Resources Research Station in Khorasan Razavi Province during the years 2016 to 2018. This study was conducted using a T-test design and the samples were compared in pairs. Six treatments including a combination of planting arrangement (15, 20 and 30 cm) and lateral spacing (60 and 75 cm) and a furrow method were compared. The results of statistical analysis showed that the drip-Tape irrigation method with a spacing of 60 cm along with a regular planting arrangement of wheat rows with a spacing of 15 cm was superior to the other treatments implemented, and the difference in the studied traits was clearly evident compared to the furrow irrigation treatment. The highest yield and water productivity were obtained from this treatment (8500 kg/ha and 1.63 kg/m3), while the irrigation water consumption in this treatment was 21% less than the furrow irrigation method in the first year and 35% less in the second year.

Reliable estimates of the seasonal applied water and irrigation performance indicators under the current orchard conditions are prerequisites for improving water resources management in agriculture. In this study, seasonal applied water, irrigation methods, and assessment indicators of sweet cherries were studied by monitoring 22 orchards under actual conditions, in Ardabil Province (Parsabad and Meshginshahr counties), Iran, during the 2020-21 growing season. The seasonal estimates of the net crop water requirement, In, during the study season ranged from 460 mm (drip irrigation with no active ground cover) to 729 mm (surface irrigation with active ground cover). The adjusted In estimates for the drip irrigation method were 19-29% lower than those for the surface irrigation, and the presence of active ground cover increased In by 31-35%. The total sum of seasonal applied water and effective precipitation (I + Pe) and the fruit yield ranged from 436-1457 mm and 1.60-16.67 ton.ha-1 (with a weighted average of 583 mm and 9.03 ton ha-1), respectively. Over-irrigation was more common in the initial and developmental growth stages compared to the middle and late stages. Most of the orchards experienced different degrees of deficit irrigation during pre- and post-harvest periods (13 and 21 orchards, respectively). On average, 60% of the seasonal applied water was allocated to the post-harvest period. There was a significant (P < 0.05) difference between the values of the relative irrigation supply index (RIS= I / In) during pre- and post-harvest periods. Water productivity indicators were significantly (P < 0.05) affected by the managers' education and skill level, orchard size, age of the trees, irrigation method, and frost damage. Frost damage accounted for a 61% and 72% reduction in fruit yield and water productivity (WPI+Pe), respectively, compared to the orchards without severe frost damage. The results indicated severely poor irrigation management in the study orchards. Controlling frost damage, and implementing regulated deficit irrigation during the post-harvest period seem to be the most significant and effective strategies to improve irrigation performance indicators in the study area.

Water shortage is the main challenge for agriculture in arid and semi-arid regions. Therefore, improving water productivity using different methods such as implementing pressurized irrigation systems is necessary. In these systems the both efficiency and distribution coefficients are vital. The purpose of this study is to investigate the performance of flow control valves in regulating the volume of water delivered in the field and saving water consumption. A flow control valve is recommanded to deliver an almost constant flow for different pressure ranges.

In this study, the performance of automatic flow control valves to adjust the water delivered in the field was investigated. For this purpose, two valves with flow rates of 5 and 10 Ls-1 were installed on a farm equipped with a drip irrigation system to evaluate the effect of the valves in a field condition. The farm is located in Mahdiabad of Takestan. The area of this field is about 12 ha. Also, EPANET software is used to model the irrigation system in different scenarios. This software can simulate the behavior of water flows in pressurized networks. To model the irrigation system, the specifications of the reservoir, water transmission lines, manifold pipes, and laterals including the length, diameter of the pipes, and elevation, were applied as the input characteristics of the program. Numerical models need to be calibrated to check the correspondence between the measured and simulated parameters. To compare the values measured and simulated by the EPANET model, statistical indices of root mean square error (RMSE), mean absolute error (MBE), and error percentage (NRMSE) were used.

Firstly, the current condition of the farm was evaluated. The results showed the water discharges were 6.4 and 12.35 L s-1 for plots B and F on-farm, respectively. These discharges were 28% and 25.3% higher than the designed discharges for parts B and F, respectively. As a result, water consumption was increased and its surplus was wasted as deep percolation or surface runoff. Then the flow control valves were installed in the suitable places. After installing the flow control valves, the water delivery condition was re-evaluated. Discharges of B and F plots were 4.86 and 9.96 L s-1, respectively. EPANET software was applied to simulate the flow in the irrigation system. The results showed that the flow control valves could be used successfully to deliver an accurate volume of water to the plots and they could compensate the effect of changes in pool water height or ruptures of irrigation tapes. By investigating the effect of changing the height of the pool water, it was found that increasing the height of the water in the pool would result in increasing the irrigation system discharge. However, by installing the flow control valve, water delivery remained almost constant by changing the water height in the pool. Additionally, by examining the performance of the valve during rupture or dislocation of the irrigation tapes, the flow through the tested irrigation fields increased. However, with the use of flow control valves, due to the structural mechanism of them, the flow rate did not exceed from the designed values. Also, the results showed that a dislocation or leakage in the irrigation tapes reduced the pressure and increased the amount of flow consumed by the irrigation system. However, the numerical modeling results showed that with the installation of the automatic control valve, the flow rate of the irrigation tapes remained in a suitable range.

Conclusion                                                              

Flow control valves regulate discharge irrespective of the pressure fluctuations. Experiments were performed to identify the ability of a discharge control valve to improve water distribution uniformity in an actual field condition. Field measurements revealed the successful application of the control valves on a farm scale. Also, numerical results indicated that the flow control valves could be used effectively to increase the flow uniformity inthe cases of the water height fluctuations in the reservoir pools or  ruptures of the irrigation tapes. In general, it was found that the flow control valve was a good choice to increase the water efficiency and uniformity in the field conditions. Numerical simulations could determine the suitable locations of the valves and their discharge characteristics.

Razavi Khorasan province is one of Khorasan provinces in northeastern of Iran, the center of this province is Mashhad. The area of this province is 118854 square kilometers. Due to having high evaporation potential and low rainfall, mostly associated with inappropriate distribution, this region is among the dry and semi-arid regions of our country, so that water is considered the most important factor limiting the development of agriculture. Nowadays, limitations in water resources has made it necessary to create ways to increase water productivity. This is a proof of the importance of careful planning and finding the use of different irrigation methods to increase water productivity in agricultural activities. Reviewing the sources indicated that the volume of water used in the cherry orchards varied in different regions and with different irrigation systems. This research aims to measure the volume of applied water, the yield, and the productivity of cherry under the management of farmers in three plains: Mashhad - Chenaran, Torghabe - Shandiz, and Nyshabor, and to compare the volume of applied water with the volume of water requirement of cherry mentioned in the national document and calculated by Penman- Monteith method using meteorological data.

This project was carried out in the field in order to determine the optimum water requirement of cherry in the orchards under the management of farmers during one cropping season (2021). Three plains: Mashhad - Chenaran, Torghabe – Shandiz, and Nyshabor were selected in Razavi Khorasan province, these plains have the largest area under cherry cultivation in the province. Based on the data required to implement the project, a questionnaire containing necessary information and logical conclusion was prepared. The required data of the selected farms in each plain were either measured or gained through interviews with the farmer or were calculated and completed according to the data obtained. The measurements were carried out in type of water source, irrigation network, irrigation method, and water source discharge. The field and area under cultivation of cherry, variety, planting arrangement, planting date, soil texture, electrical conductivity of irrigation water and soil saturation extract, date of first irrigation, irrigation cycle, different irrigation methods, etc. The volume of applied water were compared with the net irrigation water requirement estimated by the Penman- Monteith method using the last 10 years meteorological data (2011 to 2021) and also with the national water document values. Crop yield was recorded at the end of the growing season and water productivity was calculated as the ratio of yield to total water (irrigation applied water and effective rainfall).

In Razavi Khorasan province, underground water sources are facing with deficit. Therefore, efforts towards better use water and reducing exploitation of underground water resources are inevitable. In this project, the water given by the farmers for cherry production during one cropping season was measured in three plains of Mashhad - Chenaran, Torghabe – Shandiz, and Nyshabor, without interfering farmer’s irrigation schedule; these plains had the largest area under cherry cultivation in Razavi Khorasan province. The method of irrigation of the fields was surface and drip irrigation.  The results showed that the volume of applied water in Mashhad - Chenaran, Torghabe - Shandiz and Nyshabor plains were 7760, 7590 and 7740 m3/ha, respectively. The average amount of applied water, the amount of cherry yield and the water productivity in those plains were 7799 m3/ha, 7049 kg/ha and 0.907 kg/m3, respectively. Also, the average volume of irrigation water, yield, and productivity of water in the surface irrigation method were 8029 m3/ha, 6489 kg/ha, and 0.8013 kg/m3 respectively; for drip irrigation method the figures were 7638 m3/ha, 8439 kg/ha, and 0.972 kg/m3 respectively. 

The results showed that the average volume of water, yield and water productivity in three plains were 7799 m3/ha, 7049 kg/ha, and 0.907 kg/m3 of water, respectively. The difference between the volume of applied water, performance and water efficiency in two methods of surface and drip irrigation was significant. Under the drip irrigation system, comparing to surface irrigation method, the volume of applied water was 5% less (7638 cubic meters per hectare versus 8029 cubic meters per hectare), the yield was 14% higher (7439 kg/ha versus 6489 kg/ha) and the water productivity was about 20% higher (0.972 kg/cubic meter of water versus 0.813 kg/cubic meter of water).

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.

Transplanting reduces the risk of frost and shortens the plant's growing timein the field, and it is possible to do two turns of cultivation. Research on determining water productivity especially in transplantation crops, which are introduced as a strategy to increase productivity in arid regions,, is of particular importance. For this purpose, an experiments was conducted in a split-plot design within the framework of a randomized complete block design with four replications in two turns of spring and summer cultivation on transplantation and direct-seeded (seed) corn. In this experiment, the main plots included three levels of irrigation water supply (75%, 100%, and 125% of the full water requirement) and the subplots consisted of transplanted and direct-seeded corn. The results showed that in spring cultivation, yield and water productivity were higher in the transplanted treatment than in the direct-seededtreatment, but in summer cultivation, no significant difference was observed in yield and water productivity between transplanted and direct-seeded crops. In both  spring and summer cultivation, the yield difference between the 100% and 125% water requirement treatments was not significant,, but it was significant compared to the 75% treatment. Therefore, the best corn yield under the irrigation treatment was achieved by supplying 100% of the water requirement.. Overall, it can be recommended that if the main goal of transplanted corn planting is to increase yield and water consumption efficiency, this goal can be achieved by spring corn cultivation, but in summer cultivation, yield and water productivity do not increase.

The increasing population of the world and the shortage of water resources, is a serious threat to sustainable development of agriculture. Therefore, methods such as pressurized irrigation are proposed to save water consumption. For this purpose, a meta-analysis study from the beginning until September 2020, was performed to investigate grain yield, irrigation water amount and water productivity in pressurized irrigation methods on maize plants. After searching databases, 17424 studies were collected and 93 paired data were obtained by final screening. Overall, grain yield and irrigation water amount showed a significant increase of 7.65% and a significant decrease of 29.89%, respectively, in pressure methods compared to surface methods. Also, when using pressurized irrigation methods, water productivity increased significantly by 62.98% compared to the surface irrigations. In this study, sprinkler irrigation showed the highest increase in grain yield (10.42%), and drip tape irrigation showed the highest decrease in irrigation water amount (24.61%) and the highest increase in water productivity (70.22%), compared to surface irrigation. The results of this study showed the importance of using pressurized irrigation methods along with determining the appropriate method of pressurized irrigation that increases grain yield, water productivity and decreases the amount of irrigation water for maize plants

Most regions in Iran are classified as arid and semi-arid areas. The management of water resources in the agricultural sector holds great significance as it is the largest consumer of water in the country. To effectively plan and manage these resources, it is imperative to possess adequate information regarding the water consumption across different agricultural products. Given the country's reliance on sweet lime products, and the limited research conducted in this area, determining the water usage in sweet lime orchards could prove valuable for national planning and decision-making. A thorough review of existing literature indicates a wealth of information on water requirements and the impact of various irrigation methods on citrus fruit yield worldwide. However, there is a dearth of research specifically focused on irrigating sweet lime trees under the guidance of gardeners. In Iran, the management of sweet lime irrigation has also received limited attention. Therefore, this study aims to quantify and evaluate the volume of water applied and the water productivity of sweet lime trees in the country.

In this particular field study, the direct measurement of irrigation water volume and sweet lime yield was carried out in a total of 67 selected orchards located in the provinces of Fars and Hormozgan. The fruit yield was acquired over a span of three consecutive years, and the average yield was subsequently utilized in the subsequent analysis. The investigation into potential discrepancies in yield, irrigation water volume, and water productivity in the production of sweet limes was conducted through the utilization of analysis of variance. By closely monitoring the irrigation program of the gardens and assessing the cultivated area, the inflow of water to the garden was determined, subsequently allowing for the measurement of the volume of irrigation water employed by the sweet lime trees in each individual garden. The multiplication of the flow rate throughout the entire irrigation period in the season yielded the precise amount of irrigation water volume. Additionally, various factors such as the soil texture of the gardens, the electrical conductivity of both the soil and irrigation water, among others, were measured in each respective garden. The evapotranspiration of the sweet lime trees in each region was calculated by employing the meteorological data from the station closest to the project implementation area over the course of the last ten years, as well as the year of the research, using the Penman-Montieth methodology. The obtained results were subsequently compared to the calculated net required irrigation water and the values outlined in the National Water Document (NETWAT).

The outcomes revealed that there were significant disparities in the output, quantity of water applied, and indicators pertaining to water efficiency within the aforementioned regions. The average yield of sweet lime per unit area was determined to be 22.3 metric tons per hectare. The mean volume of irrigation water used and the total amount of water applied were found to be 14,192 cubic meters and 15,144 cubic meters per hectare, respectively. The mean water productivity in terms of irrigation water was estimated to be 1.70 kilograms per cubic meter. The weighted average water productivity considering both irrigation water and long-term effective rainfall amounted to 1.47 kilograms per cubic meter. Similarly, the weighted average water productivity considering both irrigation water and current year effective rainfall was calculated to be 1.60 kilograms per cubic meter. The proportion of irrigation water volume used in sweet lime orchards with respect to the overall water requirement in the selected provinces was found to be similar. In general, the average difference between the depth of irrigation water and the annual and long-term gross water requirement in the country was found to be -1 percent and +17 percent, respectively. Factors such as water and soil salinity, tree age, gardener literacy level, and soil texture were identified as some of the variables that influenced the yield, water productivity, and volume of irrigation water.

Accurate determination of the required water for plants and the volumetric delivery of water can yield highly effective results in terms of reducing irrigation water usage and increasing water productivity. Furthermore, the adherence to irrigation scheduling in sweet lime orchards has the potential to optimize the yield per unit of water allocated. When establishing or renovating sweet lime orchards, it is advisable to select cultivars that are resilient to cold and salinity, possess export capabilities, and expand the cultivation area in proportion to the available water resources.

Since water is one of the most important factors affecting the production and performance of agricultural products, the efficient management of this scarce resource is considered one of the important fields of agricultural development. The purpose of this research is to analyze and compare the cultivation pattern and the gross profit of farmers in two cases due to the implementation of price and non-price water policies and the implementation of pressure irrigation system in the fields of Erzuye city, one of Kerman province. Irrigation water price policy (increase in water extraction cost) was considered under scenarios of 25, 50, 75 and 100 percent. To achieve these goals, the positive mathematical programming model was used. In order to achieve practical results, production function with constant elasticity of substitution and non-linear cost function were added to this model. The required data were collected using simple random sampling method and completing 100 questionnaires in the crop year of 1401-1400. The obtained results showed that with the adoption of the water price policy, the cultivated area of the crops with the least water consumption increased and other selected products faced a decrease in the cultivated area. Under the last scenario, the gross profit of the model decreased by 26% and at the same time the water consumption decreased by 10.5%. Comparing showed that the implementation of this irrigation system compared to the observed level, increases the net profit of the model by 30.75% and reduces the water consumption of selected crops by 210%

Limited water resources indicate the need for optimal use of water in the agricultural sector. One of the best ways to use water is to apply deficit irrigation in modern irrigation methods, such as drip irrigation.

In this study, in order to technically and economically analyze the drip irrigation system (surface and subsurface) in the cultivation of grain maize under different levels of irrigation, an experiment in the form of split-plot and randomized complete block design with three replications was conducted in Orzooieh region of Kerman province in 2019. The treatments included three potential levels (I1= 35, I2 =50, I3=65   cm to start irrigation) as the main factor and two drip irrigation systems (surface = S1 and subsurface = S2) as the secondary factor.

The results showed that the highest volume of water use, crop yield, number of grain rows per maize, and number of grains per row were 9430 m3 per hectare, 11.32 tons per hectare, 23.45, and 48.85, respectively, in 35 centibar treatment applied in the subsurface drip irrigation system.Discussion and

While the water used efficiency in the 50 centibar treatment applied in the subsurface drip irrigation system was about 4% higher than the above-mentioned treatment, but the economic analysis showed that this treatment is in the C position. Therefore, according to the economic analysis, it is suggested that the potential point of 35 centibar applied in the subsurface drip irrigation system be used in grain maize cultivation.

Alfalfa is irrigated by drip, strip, Furrow and rain irrigation methods. Surface irrigation methods are unjustifiable and not economical due to the low potential of irrigation efficiency in dry areas. Rain irrigation methods cannot be justified in hot and dry areas due to high evaporation and high water requirement of alfalfa. Alfalfa is a plant whose leaves are sensitive to burns caused by poor quality water as a result of water spraying in the rain irrigation method (Hengeller, 1995). Micro irrigation methods (surface and subsurface drip) are among the alternative methods of rain methods. The subsurface drip irrigation method has not been developed in Iran due to the existence of ambiguities and some dark and unclear points regarding its efficiency for crops (clogged outlets, salt accumulation, risk of blockage of pipes by roots). These concerns require that before any development of subsurface drip irrigation method for different crops, necessary researches should be done in this field. Therefore, conducting any research on the efficiency of this method for alfalfa, which is a valuable fodder plant but requires a lot of water, seems necessary. This research was conducted with the aim of investigating the effect of subsurface drip irrigation method on alfalfa yield, the amount of water consumed and determining the appropriate distances and depths for sub-pipes.

In order to investigate the effect of installation depth and distance of irrigation strips (laterals) in subsurface drip irrigation method on yield and water use efficiency in alfalfa cultivation, a study was conducted for two years on the farm of Damghan Agricultural Research Station. The design was implemented in the form of split strips based on randomized complete blocks with two factors and three replications. Factors included: 1- Distance of irrigation strips from each other in three levels (80, 100 and 120 cm) 2- Depth of installation of irrigation strips in two levels (30 and 45 cm below the soil surface). Depth of strips installation was considered as the main factor and distances as the sub-factor. The length of each experimental plot was 60 m and the width of the plots for the distances of 80, 100 and 120 cm were selected as 4, 5 and 6 m, respectively. Strips irrigation with a with a diameter of 20 mm with a discharge of 1.6 (lit/hr) and a distance of 60 cm for each dropper were selected. After preparing the ground and sowing the seeds, the subsurface irrigation pipes were placed (according to the treatments) with using the machine. Irrigation water was calculated by Penman-Monteith method and was given to the plant with an irrigation cycle of 4 days.

The results showed that the effect of pipe spacing on product yield (dry matter) and water use efficiency was significant, but the effect of pipe installation depth on yield and water use efficiency was not significant. The interaction effect of distance and depth of tapes irrigation on crop yield and water use efficiency was significant. There was no significant difference between crop yield in treatments with lateral distance of 80 and 100 cm. With increasing lateral distance from 80 to 120 cm, crop yield decreased sharply. Due to the yield of treatments and the cost of subsurface drip irrigation, the treatment of lateral distance of 100 and depth of 45 cm was suggested as the superior treatment.

The subsurface drip irrigation method for perennial crops is one of the efficient and appropriate methods. This method has a much higher efficiency than other irrigation methods due to the reduction of evaporation losses and the increase of irrigation efficiency especially in arid and semi-arid areas. The non-interference of irrigation in this method with the traffic of agricultural machines (especially during harvest) increases the ability and functionality of this method. But one of the problems of this method is the damage of rodents to the sub-pipes under the soil surface, which makes it difficult to determine the places of damage and repair them. Based on the results of this research, to prevent the damage of rodents, it is recommended to fight against these rodents and also to increase the installation depth of secondary pipes up to 50 cm. Clogging of droppers caused by poor filtration performance and penetration into and around the pipes are other problems of this method. To avoid these problems, it is recommended to inject acid and herbicide regularly into the irrigation system.

It is necessary to evaluate irrigation systems in order to determine their optimal performance, modify and manage them. In this research, five drip irrigation systems in Salas Babajani city located in Kermanshah province were selected and evaluated based on the instructions of the American Soil Conservation Service (SCS) and Merriam and Keller methods. The results of investigations showed that the wetted area ranged between 14.89 and 33.49 percent of the total area. The minimum and maximum values of water distribution uniformity in the investigated systems (EUs) were determined as 29.49 and 62.56 percent, respectively. The values of lower quartile application potential efficiency (PELQs) and lower quartile application efficiency (AELQs) of the systems fluctuated between 26.83 to 53.3 and 29.48 to 62.56 percent, respectively, which indicate the poor performance of the systems in all fields. According to Langiller Saturation Index (LSI) values obtained from water sources in the fields under study, in two fields, there was a tendency for calcium carbonate precipitation, but in other fields, there was no risk of precipitation. In general, the poor performance of the systems were due to various reasons, such as: not installing a central control station or a suitable filtration system, insufficient wetted area, inappropriate type and number of droppers, clogging of the droppers, pressure difference in the systems, inappropriate pressure and its uneven distribution, inappropriate distance and duration of irrigation and finally the poor management of exploitation.

Irrigation performance assessments under actual operation conditions are required as a first step toward improving agricultural water management. In this study, the seasonal irrigation performance of peaches and nectarines was evaluated under actual operation conditions by monitoring 24 orchards, in Ardabil Province (Parsabad and Meshginshahr counties), Iran, during the growing season 2018-2019. The total sum of seasonal applied water and effective precipitation (I + Pe) and the fruit yield ranged from 280-1675 mm and 1.00-32.43 ton ha-1 (with a weighted average of 582 mm and 14.61 ton ha-1), respectively. The mean Relative Irrigation Supply index (RIS) for the drip irrigation method (1.25) was significantly (P < 0.05) lower than the surface irrigation method (1.66). The water productivity indicators were significantly (P < 0.05) affected by the orchardist's skill level, interplantion of trees, tree spacing, irrigation method, and disease/frost (DF) damage. Post-harvest period accounted for a mean proportion of 75, 25, and 15% of the seasonal applied water in orchards with early-season, late-season, and mixed early- and late-season cultivars, respectively. DF damage accounted for an 87 and 85% reduction in fruit yield and water productivity (WPI+Pe), respectively, compared to the orchards without severe DF damage. Under the current technological and economic constraints, most of the study orchards experienced a rational (but yet with low productivity) irrigation water management. Improving irrigation efficiency and fruit yield, controlling DF damage, and implementing regulated deficit irrigation during pre- and post-harvest stages are the most effective approaches to improve water productivity indicators in the study area.

Rice is one of the important food products that is generally transplanted. The rice “dry seeding method (DSM)” is a new approach that has provided an opportunity to increase water productivity. In this research, changing the cultivation method from transplanting to DSM and using pressurized irrigation instead of flooding method was studied in 5 rice fields in Golestan Province. The field with flood irrigation method was considered as the control treatment. Other fields were cultivated in dry soil and irrigated by drip and sprinkler methods. The results showed that, in all parameters related to grain yield and yield components, the field with flood irrigation method had higher values. Economic study at the different growth stages with different irrigation methods showed that by changing the planting method and removing the puddling in rice field, 4000 to 7000 cubic meters of water can be saved. Comparison between different irrigation methods showed that the sprinkler irrigation had a higher average yield (4998 kg/ha) than drip irrigation) 4426 kg/ha(. With 30% yield reduction, this method saved 61% in water use, which is a significant amount. The highest and lowest physical (0.53 and 0.3 kg/m3) and economical productivity rates (141,791 and 82,704 Rials/m3) were related to sprinkler irrigation and flood irrigation, respectively, which show very low water productivity in the rice fields of the province. This shows the need to increase water productivity under the current climatic conditions of the country.

Population growth and limited water and soil resources make it necessary to pay attention to the factors affecting food production, including the suitability of irrigation methods with agricultural lands. The objective of this study was to assess land suitability for surface, drip, and sprinkler irrigation methods based on a parametric evaluation system in an area of 250 hectares in the Shahid Rajaei plain of Khuzestan. Soil properties were analyzed, then suitability maps for different irrigation methods were prepared using a geographic information system (GIS). The results showed that for surface irrigation, 704 ha (31.3%) was marginally suitable (S3), 866 ha (38.5%) was currently not suitable (N1), and 680 ha (30.2%) was permanently not suitable (N2). For drip irrigation, 8 hectares (0.4%) are highly suitable (S1), 644 hectares (28.6%) are moderately suitable (S2), 52 hectares (2.3%) are marginally suitable (S3), 866 hectares (38.5%) were currently not suitable (N1), and 680 hectares (30.2%) were permanently not suitable (N2). For sprinkler irrigation, 652 hectares (29%) are moderately suitable (S2), 52 hectares (2.3%) are marginally suitable (S3), 866 hectares (38.5%) are currently not suitable (N1), and 680 hectares (30.2%) were permanently not suitable (N2). According to the results, sprinkler irrigation with an irrigation capability index of 29.9 to 60.7 in 2242 hectares (99.6%) is preferable to other irrigation methods. Drip irrigation in 8 hectares (0.4%) was found to be the most suitable method. The main limiting factors in using all three irrigation methods included salinity, alkalinity, and drainage. Also, soil calcium carbonate was added to the limiting factors in drip irrigation.

Fars province is one of the prominent provinces in the country in the production of oranges and tangerines. Having sufficient information on the volume of irrigation water and water productivity in orange and tangerine orchards can lead to better management of water resources and increase water productivity. In this research, water productivity and irrigation water volume were measured in 60 orange and tangerine orchards in three regions of Fars province during the crop year 2019. Among the selected orchards, due to differences in irrigation management, the state of water resources and soil conditions, the volume of irrigation water varied from about 8800 to 24700 m3/ha/yr. The average total volume of irrigation water in orange and tangerine orchards was 15388 and 15093 m3/ha, respectively. The average volume of applied water, which is the sum of effective irrigation and rainfall, was 18289 and 17867 m3/ha, respectively. The average fruit yield for orange and tangerine orchards was estimated as 18.4 and 20.8 t/ha, respectively. The productivity of irrigation water in selected orchards was between 0.45 and 3.03 kg/m3 and on average for orange and tangerine it was 1.30 and 1.44 kg/m3 respectively. Comparing the volume of irrigation water with the gross water requirement showed that in the year of conducting the research, the volume of irrigation water was on average 4400 m3/ha or in other words 41% more than the required water. The average difference in the volume of irrigation water with the long-term gross water requirement was about 4000 m3/ha. Considering the area of orange and tangerine orchards in the three regions of Darab, Jahrom and Kazeroon, the amount of water saved will be 46, 8 and 14 Mm3/yr, respectively.

Due to decreasing water resources and increasing irrigation interval in gardens, implementation of modern irrigation systems such as under-pressure irrigation is necessary. But the main concern is the effects of changing traditional irrigation systems to under-pressure irrigation systems from the point of view of supplying water needs of old trees and temporal variations of soil characteristics. In this study, two methods of subsurface-flood irrigation and surface-drip irrigation were implemented in Yazd Agricultural and Natural Resources Research and Education Center. The soil water content was monitored during the experimental period (18 May 2019 to 10 January 2020) by installing TDR probes in three soil depths of 15, 30 and 60 cm for each irrigation method with three replications. The results showed that soil water content at the soil depths of 15 cm and 30 cm were higher for surface-drip irrigation as compared to the subsurface-flood irrigation at the end of the irrigation interval. Two days after irrigation, the effects of subsurface-flood irrigation on soil moisture distribution became apparent at the deep layers of the soil, such a way that soil water content at the soil depth of 60 cm was higher for subsurface-flood than surface-drip irrigation. The measuring of the soil water content at the soil depth of 60 cm in subsurface-flood irrigation showed that the irrigation interval could be increased about 9 days as compared to the surface- drip irrigation. However, because of applying water below the soil surface for the subsurface- flood irrigation, the salinity increment occurred at surface soil.

This study determines the amount of irrigation water saved as a result of the subsidy policy to adapt from flood to drip irrigation. We developed a positive mathematical programming model (PMP) to evaluate the effect of economic incentives on farmers’ decisions to choose the type of irrigation technology, cropping pattern, and "water use" and "water consumption" in rural Garkan Shomali district, which is part of the Najafabad aquifer. We collected data through farm surveys, desk research, and expert interviews. The results showed that a reduction in the financial costs of converting flood irrigation into drip irrigation can lead to farmers investing in this technology. In the current water allocation scenario, the subsidy policy increases the water consumption of drip-irrigated crops by 28%, of which 19% is non-consumed water before subsidy payment and the rest is related to the reduction of furrow-irrigated lands. Also, under non-volumetric water delivery conditions, the operating costs reduce and the net income of the farms increases because of the increase in efficiency and the development of the area under cultivation, which increases water consumption while the water use is constant. In the volumetric water delivery scenario, with the increase in subsidies, the net income of the farms will increase without developing the area under cultivation and only because of the increased yield. Therefore, subsidy policy increases irrigation efficiency at both the farm and regional levels and is an effective tool for dealing with drought conditions.

This study aimed to evaluate the efficiency of wick irrigation system in greenhouse cultivation of tomato plant and compare it with drip irrigation. The experiment was performed as factorial with a completely randomized design (CRD) in the research greenhouse of Tarbiat Modares University in 2021. Irrigation treatments included five levels (drip irrigation and wick irrigation with diameters of 1, 3, 4, and 5 cm) and two soil combination ("cocopeat, soil, fertilizer, perlite" and "soil, sand, fertilizer"), in 3 replications. The lowest and highest water consumption during the growing season was observed in wick irrigation with a diameter of 1 cm (29.25 L/plant) and in drip irrigation and wicks with a diameter of 5 cm (36 and 37.5 L/plant), respectively. The results showed differences of 19% and 4% in water consumption between, respectively, wick irrigation with a diameter of 1 and 5 cm compared to drip irrigation. Also, the difference in water consumption between wick irrigation (minimum and maximum water consumption) of 1 and 5 cm diameters was 28%. The yield in "soil, sand, fertilizer" cultivation bed was increased by 59% compared to the "cocopeat, soil, fertilizer, perlite" cultivation bed and the maximum tomato yield (700gr/plant) was observed in the wick irrigation with a diameter of 3 cm. Water consumption index in "soil, sand, fertilizer" cultivation bed was decreased 21%, rather than "cocopeat, soil, fertilizer, perlite" cultivation bed and increased water productivity by 100%. In wick irrigation, since water is always available, the plant does not face water stress and these results indicate that the wick irrigation system improves plant growth and increases production of wet and dry matter and water productivity in tomato plant. Although economic analysis has not been done in this research, but more crop yield along with less water consumption in the wick irrigation system would have more income for the user and can be an acceptable reason for using this irrigation method.