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To monitor and compare the changes of salts in the soil profile around the roots of the corn plant, the plant yield, and the productivity of corn water, an Experimental was conducted in a completely randomized block of three repetitions in two crop years 2017-2018 and 2018-2019 at Ahvaz Agricultural Research Station. Experimental treatments included two subsurface drip irrigation systems with a working depth of 30 cm from the soil surface and tape irrigation and two irrigation intervals of 2 and 4 days. The results of monitoring soil solutes obtained from sampling depths (0-25, 25-50, and 75-50 cm) showed that soil salinity in the second year in both systems as a result of improving the quality of irrigation water from 3.61 dS/m to 2.01 dS/m, it was reduced by two times. The results of soil salinity monitoring showed the highest ratio of salinity reduction with a 2-day irrigation interval in both irrigation systems. The most leaching was done at the irrigation depth of 25-50 cm in the subsurface drip irrigation system and at the depth of 0-25 cm in the tape system. The highest yield of corn dry fodder was 9.13 and 7.13 tons per hectare, respectively, and the best water efficiency based on dry corn fodder at the rate of 13.74 kg/m was obtained in the strip drip irrigation system (tape) with a two-day irrigation interval and in the second crop year. Also, the results of the soil salinity measurement showed that the implementation and exploitation of the drip irrigation system can be the basis for improving the quality of the soil as the most important non-renewable resource of agriculture. [ABSTRACT FROM AUTHOR]

Shifting of surface irrigation to drip system is key tool to reduce water saving. Due to the soil moisture profile variation of the drip irrigation; water distributed of the root zone is not uniform. Moreover, moisture deficit and inefficient fertilizing in drip system due to unavailability in deeper layers of soils is one of the disadvantages of drip system in pistachio orchards with depth root systems. An experiment was carried out by adjusted subsurface drip irrigation (SSDIadj) system in pistachio of Damghan region (Semnan province) in a randomized complete block design with split plot arrangement in three replications for three years. The potassium fertilizer amounts (Fertigation) at three levels (50, 70, and 100% of requirement) were considered as the main plot and the design of conductor tubes of the SSDIadj system in seven levels as sub plots. The irrigation guide tubes were arranged for sand tube irrigation in (control), 40-40- 40-40, 40-40- 50-50, 40-40-60-60, 40-40-50-60, 40-40-50-70, and 40-40-50-80. Meteorological data from the nearest meteorological station was collected and analyzed. Yield, water consumption, irrigation water productivity index and growth conditions of ShahPasand pistachio cultivar were determined in different treatments. Data were analyzed using Genstat-12 software and based on the analysis of surplus costs and aerial data, the best treatment including combination of potassium fertilizer and arranged tubes of SSDIadj system was determined. The recommended treatments are including of full irrigation, full potassium fertilizer and guide tubes 40-40-50-70 and or 40-40-50-80. The treatments with stratified conductive tubes in the optimal distribution of water, improving productivity and reducing inefficient consumption water. In addition, there are no restrictions on subsurface irrigation such as root accumulation, root penetration into pores of drippers and as well as accumulation of salts. [ABSTRACT FROM AUTHOR]

Due to water scarcity, it is impossible to utilize all irrigated cropland in arid and semi-arid areas. Therefore, dense cultivation with a drip irrigation system that delivers water directly to the plant's root zone is an appropriate choice to enhance water productivity. The objectives of the present study were to compare wheat yield and water productivity under two different water distribution patterns in the drip-tape irrigation system and surface irrigation in full irrigation and deficit irrigation levels. The experimental treatments consist of two irrigation systems (drip-tape (DT), and surface irrigation (SU)), and three different irrigation levels (a full irrigation level (W1), two deficit irrigation levels, the irrigation interval twice, and the same irrigation depth of W1 level (W2), applied half of the irrigation depth of W1 level at the same time (W3)). The SU was implemented in place with 100% efficiency to avoid runoff. The yield in full irrigation level in DT was 5338.4 kg/ha and in SU was 5772.8 kg/ha. Applying deficit irrigation in two irrigation systems has different effects due to various water distribution patterns. In the DT, the most yield reduction was in W2, and in SU was in W3. The highest water productivity in DT was observed in W3 with a 1.44 kg/m³ value. The highest water productivity in SU was observed in W2 with a 1.46 kg/m3 value. For each irrigation system, some type of deficit irrigation management is optimal. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

For the proper use of water resources and prevention of soil degradation, it is necessary to select the best irrigation system. The aim of this study was to map the land suitability evaluation for different irrigation methods (surface and drip) in 46000 ha of Sistan plain including Hirmand, Hamon, Nimroz, Zahak, and Zabol counties. For this purpose, 600 pedons with an approximate distance of 700 to 800 m were excavated, described, and sampled. In this study, land suitability evaluation for different irrigation methods based on soil properties and topography was done using the parametric method. Then, land suitability maps for surface and drip irrigation methods were prepared using the Inverse Distance Weighting (IDW) method. The results showed that in the studied area, the conditions for drip irrigation are better than the surface irrigation method. However, in many studied areas, there are restrictions for drip irrigation, and for proper and efficient use of this irrigation system, the restrictions must be removed. Moreover, the results confirmed that in all studied areas the most important limitations are salinity/alkalinity and limitations due to physical soil properties. The silty clay and silty loam textural were the most limitation classes. Due to the fact that changing the physical properties is not easily possible, it seems that soil remediation based on salinity and alkalinity can help to remove or reduce the limitations. [ABSTRACT FROM AUTHOR]

Increasing crop production per unit volume of water consumption requires recognizing the most dependent variable in drip irrigation to the volume of water consumption and also identifying the most important variables independent of water productivity in surface and subsurface drip irrigation for optimal use of available water resources. The present research was carried out in Behbahan Agricultural Research Station during four cropping seasons (2013-2017) on a Kabkab date variety. Experimental treatments include the amount of water in the subsurface drip irrigation method based on two levels of 75% and 100% water requirement and in surface drip irrigation based on 100% water demand. Data were analyzed using a randomized complete block design with three replications. The results of the analysis of variance of the mean of different irrigation treatments in quantitative traits showed that the effect of irrigation was significant at the level of 1% in terms of cluster weight index, fruit weight, and fruit flesh to kernel weight ratio. The results of regression analysis of variance showed that in the dependent variable of cluster weight, the consumption water volume explained 19.1% (R2 = 0.191) of the fluctuations of the dependent variable (cluster weight). Among all the studied variables, the volume of water consumption explained the most significant changes in date cluster drying. Fruit moisture with t (2.096) and equivalent beta coefficient (0.046) had a significant positive effect on water productivity at the level of 5%. The results of the Pearson correlation coefficient showed that the effect of yield on changes in water productivity was much greater than the volume of water consumed so the yield caused significant changes in water productivity. While the effect of water consumption on water productivity was not significant. [ABSTRACT FROM AUTHOR]

Due to limited access to water, it is necessary to determine the comparative advantage of crops and horticultural products in different parts of the province and identify products that lack the desired productivity. Then, find ways to improve water productivity or replace products with higher comparative advantage with low-yield products. Based on this, the crop and economic productivity index of the province's agricultural and horticultural products under surface irrigation systems was determined. Based on the results of gross economic productivity of horticultural products, pistachio with 48690 Rials per cubic meter had the highest economic productivity, and grapes with 30220 Rials per cubic meter (62% of pistachios) was in second place. In addition, water quality for pistachios can never be generalized for grapes and other crops, and this is a tremendous advantage for pistachios that low-quality water resources can also be used. The lowest gross economic productivity of water for barley, alfalfa, and wheat is equal to 3790, 3990, and 4570 Rials per cubic meter, respectively. The study of fodder corn shows that the net profit from the cultivation of this crop in the surface irrigation system is equal to 51.78 million Rials per hectare and its net profit in the strip drip irrigation system (tape) is equal to 110.87 million Rials, which it has a 2.14-fold increase compared to the conventional irrigation method. The comparative advantage of horticultural products was higher than that of crops, and the replacement and development of orchards instead of some crops is recommended as a solution. In addition, solutions that can be recommended to improve the productivity index include the use of a drip irrigation system (tape) for crops (fodder corn, tomatoes, summer crops, and potatoes) and the use of drip irrigation (normal, subsurface, and subsurface modified drip) for horticultural products. Examination of practical experiences of using tape irrigation system for wheat and barley showed that this method has not improved the agricultural and economic productivity index, which indicates the lack of comparative advantage of wheat and barley cultivation in Semnan Province even with tape irrigation system. [ABSTRACT FROM AUTHOR]

To investigate and evaluate the effects of different levels of drip irrigation on grain yield and yield components, oil yield, seed oil percentage, and seed water use efficiency, an experiment was performed at Behbahan Agricultural Research Station during two crop years 2018-19 and 2019-20. The experiment was conducted in split plots based on a randomized complete block design with 3 replications. The amount of water in tape drip irrigation was compared at four levels of 40, 60, 80, and 100% water requirement in main plots and two sesame cultivars Local of Behbahan and Shevin in subplots from the beginning of flowering. Comparison of mean interaction effects of irrigation levels and cultivars showed that the treatment of 100% water requirement in the Behbahan local cultivar with the yield of 1218.0 kg/ha was ranked first and foremost. Water consumption in the highest treatment (100% water requirement and Behbahan local cultivar) was calculated to be 5389.4 m3/ha. Treatments of 100% and 80% of water requirement in superior cultivar (local Behbahan) with water use efficiency of 0.226 and 0.210 kg/m3 had no significant difference, respectively, and were in the first place. Pearson correlation coefficient calculated for the measured traits showed that the highest correlation of water volume was calculated (r = 0.9271) with the weight of one thousand seeds. Significant correlations of water volume with grain yield and yield components indicated that sesame was susceptible to drought stress and attention to optimal water management in sesame cultivation. Therefore, decreasing the volume of water consumed and consequently drought stress in sesame reduced yield and yield components. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of the type drip of irrigation methods, subsurface irrigation and furrow irrigation on the domestication of Hedysarum criniferum Boiss., an experiment with a randomized complete block design with three replications was implemented at Isfahan University of Technology for two years (2016 to 2018) . For this purpose, clay pipes were made and the plant was cultivated on the sides of clay pipes and types. Also, furrow irrigation treatment was applied as the control. During the experiment, all treatments received the same water and finally, some growth parameters were measured. The results of the study showed improvement in height (0.43 and 0.34), canopy cover (0.66 and 0.52), stem number (0.44 and 0.85), chlorophyll index (0.45 and 0.45), seed emergence (0.75 and 0.30), plant survival (0.78 and 0.55), yield (0.23 and 0.35), and water use efficiency (0.25 and 0.25) under type drip irrigation treatment, as compared to subsurface and furrow irrigation, respectively (P<0.05). In general, the type drip treatment is recommended in the early years of planting; however, since the maximum production potential of this plant is in the third year onwards, it is necessary to examine the results in the following years to recommend the proper irrigation method, especially the use of subsurface irrigation. [ABSTRACT FROM AUTHOR]

Optimal use of water resources seem to be necessary due to climate change and the recent drought conditions. One of the most important and effective management strategies is increasing water productivity in agriculture. Irrigation method and the use of different levels of nitrogen fertilizer are the effective factors in increasing the water productivity. Therefore, this study was conducted to investigate the effect of the irrigation method and nitrogen fertilizer on the harvest index and water productivity of two wheat cultivars with 36 treatments as a split-split plot based on a completely randomized design with three replications in the research farm of Natural Resources and Agricultural Research Center of Kashmar, during the 2018-2019 time period. The treatments were two irrigation methods including end blocked border and drip irrigation (tape) as the main plots, three levels of the nitrogen fertilizer from urea source including 0, 50 and 100 kg/ha as the sub plots and two cultivars of wheat including Pishgam and Sirvan as the sub-sub plots. The results showed that by changing the border irrigation method to the drip irrigation (tape) method, the harvest index and water productivity were increasesignificantly. The results also showed that grain yield and its components, including harvest index and water productivity, had no significant difference in 50 and 100 kg/ha nitrogen levels. On the other hand, grain yield and its components, harvest index and water productivity, were significantly higher in the Sirvan cultivar rather than the Pishgam one (P<0.01). According to the results obtained from this study, the drip irrigation method, 50 kg/ha nitrogen level and Sirvan cultivar could be recommended for the study region. [ABSTRACT FROM AUTHOR]

Today, one of the biggest challenges facing the world is the lack of water, especially in the agricultural sector. In this research, we investigated the effects of irrigation method and deficit irrigation with the urban refined effluent on biomass, grain yield, yield components and water use efficiency in single grain crosses 704 maize. This research was carried out in a randomized complete block design with two irrigation systems (furrow irrigation (F) and drip irrigation (T)) and three levels of deficit irrigation treatments of 100 (D1), 75 (D2) and 55 (D3) percent of water requirements in three replications, in 2017, at the collage of Abourihan Research field, University of Tehran, in Pakdasht County. The results showed that the highest yield of biomass was 2.426 Kg m-2 for full drip irrigation treatments; also, there was no significant difference between D1 and D2 treatments. The highest grain yield was 1.240 kg m-2 for the complete drip irrigation treatment. The highest biomass water use efficiency was obtained for the treatment of 75% drip irrigation, which was equal to 5.3 kg per cubic meter of water. Therefore, a drip irrigation system with 75% water requirement is optimal and could be recommended. [ABSTRACT FROM AUTHOR]

The Plant Water Resistance Index (CWSI) is a tool that can be used for the rapid monitoring of plant water status, which is a key requirement for the accurate product irrigation management.The purpose of this study was to calculate the CWSI index for bean hares in the Khorramabad region for two methods of surface irrigation and drip tape irrigation. For this purpose, a design was implemented in the form of randomized complete block design and split plot experiment. The main factors included drip tape irrigation (T) and surface irrigation (F), and the cultivars of Chibi cultivars including COS16 (C), Sadri (S) and diluted (K) served as sub-plots. By using the field measurements, the position of the upper and lower base lines was estimated for each treatment in different months and used to calculate the CWSI index. The results showed that CWSI values calculated in the surface irrigation during plant growth period were always higher than those in the drip tape irrigation. The highest value of CWSI index was obtained for the Sadri variety, which was equal to 0.20 and 0.26, for the type and surface method, respectively. Statistical analysis showed that the effect of irrigation method on the amount of water stress index was significant at 5% level, but there was no significant difference between different cultivars. According to the results of this study, the threshold values for CWSI were considered to be 0.19 and 0.24 for surface and drip tape irrigation respectively, and relationships were presented based on the differences in vegetation and air temperature to determine the irrigation time. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Localized irrigation methods can be used to manage low water holding capacity in the sandy soils. In this research, the effects of different irrigation systems including pot, tape and drip irrigation with gravity pressures of 0.5, 1.5 and 3 meters on the sandy soil moisture distribution under watermelon cultivation were compared with the furrow irrigation as the control treatment. The moisture content of the soil at different depths and at the distance of 5 and 20 cm from the plant was measured using the TDR device. Water distribution study showed that in the pot irrigation method, the moisture content of different depths of soil was kept constant by 16% during the irrigation interval, but the highest moisture content was observed in gravitional drip irrigation treatment at the depths of 40, 50 and 60 cm; in contrast, the lowest amount of moisture was observed in the pot irrigation treatment. In tape and gravitional drip irrigation system with gravity pressure, in addition to the adjustment soil moisture up to 15 to 22% within the wetting front, soil moisture can be kept almost constant by pulsed irrigation technique. Therefore, while providing the use of drip irrigation system with minimum water pressure available in most of the agricultural land (0.5 m), using pot irrigation can ensure sandy soil moisture retention and soil for the cultivation of fruits such as watermelon plants. [ABSTRACT FROM AUTHOR]

Wetting pattern in a trickle irrigation system is one of the most important characteristics that should be taken into consideration for designing the irrigation systems. Improving the dimensions of the wetting pattern will increase the water use efficiency and irrigation systems. The objective of this study was to investigate the effect of rice husk and its biochar application on the wetting pattern in a silty clay soil under surface trickle irrigation. A box with the length of 200, the width of 50 and the height of 100 cm was used. To easily fill and empty the model, it was filled up to a height of 50 cm. The rice husk and its biochar were added to the soil at the rates of 0, 1 and 2 mass percentages based on a factorial arrangement of the treatments in a completely randomized design with three replications. Biochar was prepared in a special furnace at 500°C without oxygen. The experiments were done with a flow rate of 4 liters per hour with the irrigation time of 3 hours. The results of the analysis of variance showed that the organic treatments increased the soil water content in the range of field capacity to a permanent wilting point; the highest increase was observed for the biochar 2% treated soil. Also, the addition of rice husk and biochar in the silty clay soil reduced the horizontal advance and increased the vertical advance wetting pattern. [ABSTRACT FROM AUTHOR]

Subsurface drip irrigation systems, compared to other irrigation systems (basin and furrow), enhance the delivery of water and nutrients directly into the root zone. The purposes of this study were to determine wetting front advancement in a subsurface drip irrigation and to compare the results with the HYDRUS 2D model simulation. In this study, the irrigation using T-Tape was carried out on a sandy-loam soil by two emitters at different irrigation times. The Wet moisture meter device was used to determine the soil water content. Evaluation of the simulated and measured soil water content was performed by using the adjusted determination coefficient (R2), relative error (RE), and the normalized root mean square error (NRMSE). Based on the results, the NRMSE of soil water content prediction for the emitters at the depths of 20 and 40 cm was calculated to be in the range of 10 to 19 and 10 to 13 percent, respectively. Also, RE for the emitters at depths of 20 and 40 cm was in the range of -16 to -5 and 8 to 11 percent, respectively. The average R2 for the emitters at depths of 20 and 40 cm was calculated to be 0.87 and 0.98, respectively. Also, five scenarios (F1, F2, T1, T2 and S1) were evaluated to assess the amount of water stored in the soil profile and water mass balance. The results indicated that the model could be used to predict the soil water content subsurface drip irrigation. [ABSTRACT FROM AUTHOR]

Accurate design of drip irrigation systems requires sufficient understanding of horizontally and vertically distribution of water flow in soil and modeling the wetting pattern dimensions created under the drip source. Field and laboratory activities are not suitable for this purpose considering their time and financial constraints and it is necessary to apply accurate software for determination of several equations in different situations. This research aimed to present simple models for calculation of wetting pattern dimensions in different discharges and structures in drip irrigation system. For this purpose, HYDRUS-2D model was implemented for four discharges in the same soil texture and different soil textures in the same discharge. The values obtained from running the software such as depth and maximum diameter of wetting pattern have been fitted with time values and corresponding equations were obtained. The results of statistical indices for all obtained equations (R>0.96, RMSE<2.12 and MAD<1.38) represent suitable accuracy of corresponding equations in determination of pattern dimensions under the drip source. The results also showed that Loamy Sand and Silt textures, respectively, have maximum and minimum depth and wetting pattern diameter. [ABSTRACT FROM AUTHOR]