مجله پژوهش آب در کشاورزی
سال سی و یکم شماره 4 (زمستان 1396)

In this research, after calibrating and validating the DSSAT-CERES Maize model, the integrated effects of modifying planting date and irrigation water depth on maize water use efficiency was investigated for four stations of Gharakheil, Babolsar, Ramsar and Noshahr in Mazandaran Province. In this regard, the model was first calibrated and validated based on data collected in a two-year maize cropping system in Sari county under three irrigation treatments i.e. full irrigation and deficit irrigation at two levels of 55% and 75%, during 2010 and 2011 growing seasons. Then, the water-yield functions were determined for the selected cropping calendars over the period 10 April till 29 June, and for the four selected stations. Thereafter, the optimal irrigation depth, aimed at preventing significant reduction in crop yield, was determined. Based on the selected criteria and indices, the model was accurate enough for simulating leaf area index, the important morphological calendars, total dried biomass, maize grain yield and total crop N uptake. Except for Gharakheil station and regardless of the irrigation treatment, delaying planting date may reduce the optimal irrigation water depth by 14-75% due to the decreased length of the cropping cycle. Based on the 30-year average weather data, the lowest optimal irrigation water depth in Babolsar, Noshahr, and Ramsar was 366, 200 and 122 mm, respectively, which will be obtained under the cropping calendars of June 9, June 29 and June 29, respectively. Nevertheless, the difference in the optimal irrigation water depth between the full irrigation treatment and the deficit irrigation treatment will be higher under early planting date. Based on the results, irrigation water depth management and modifying the cropping calendars may result in a 1.6-22.8% water saving under maize cropping systems in Mazandaran Province. Nevertheless, validating the given results of this research requires carrying out the other field investigations in the selected sites and under the proposed cropping calendars.

The objective of this study was to evaluate the design and the management of the solidest sprinkler irrigation systems in Asadabad plain of Hamedan province. For this purpose, 10 solid-set sprinkler irrigation systems of Asadabad plain were selected and some performance indicators such as Christiansen’s coefficient of uniformity (CU), distribution uniformity (DU), potential application efficiency of low-quarter (PELQ), actual application efficiency of low-quarter (AELQ), wind drift and evaporation losses (WDEL), deep percolation losses (DP) and adequacy of irrigation (ADirr) were used for evaluation. The mean values of these parameters were obtained as 75.26%, 56.76%, 45.4%, 34.65%, 28.92%, 31%, and 90.46 %, respectively. All of the systems had low PELQ values and also their water distribution uniformity was lower than the values recommended by Merriam and Keller. On the other hand, due to deficit irrigation, in all but seven systems, the AELQ values were equal to PELQ. Unsuitable design and implementation of the systems were recognized as the most important reason of low PELQ. One of these most important factors was unsuitable pressure. Simaltaneous use of many sprinklers was also an important reason for low DU. The results of the study showed that, in many cases, operation of the system was very weak. Generally, the results showed that the proper design and implementation of the solid set sprinkler irrigation systems will be useful when the management of those systems were convenient and efficient.

Poor performance of irrigation networks due to improper management and operation of irrigation canal structures has attracted the attention of managers to improve operational management of these structures. Regulating in-line reservoirs can have significant impacts on performance improvements of operational management of irrigation systems. To this end, good coordination between inlet and outlet structures as well as downstream demands should be provided. Under the condition that control and management of the reservoir is done with good coordination with other sectors, the flow in the canal would be more stable. This leads to decrease in the water level fluctuations and better services to water users. Reservoir operation and management investigation requires applying hydrodynamic models. In this study, hydrodynamic model of ICSS was adopted for modelling the flow in the regulating reservoir of Moghan Irrigation Network. Eight operational scenarios for entrance hydrograph to the canal system were considered, which consisted of gradual and sudden decreasing of inflow for two status of (i) non operation and (ii) with reservoir operation. Similar scenarios were assessed for the increasing mode as well. The results indicate that response time of the system and stability of water delivery improve by applying reservoir operation. In the decreasing scenarios, the adequacy indicator improves, while in the increasing ones, the efficiency indicator of water delivery increases when the reservoir is operated. According to the results, the latter improvement for the main off-take was obtained as 0.45% and 6.75% for, respectively, adequacy and stability.

In order to investigate the effect of different amounts of municipal compost and super absorbent polymer on yield of tomato (Solanum lycopersicum) and water use efficiency in greenhouse a factorial experiment was conducted with two factors in randomized complete block design in four replications in Khorasan Razavi Agriculture and Natural Resource Research and Education Center (torough station). First factor was four levels of compost including (C0=0, C15=15%, C30=30% and C50=50% weight of soil) and second factor was super absorbent polymer at four levels including (G0=0, G5=5, G10=10, G15=15 gram per pot). All fertilizers according to soil test as well compost and super absorbent polymers were used before planting. Pots were irrigated at 50% allowable moisture depletion. Results showed that interaction effect of Hydro gel and compost on yield of tomato was significant and the highest yield was 3520 (gr/pot) obtained from C30G0 treatment. The lowest yield was 1588 (gr/pot) and obtained from C50G15 treatment. Results showed that interaction effect of Hydro gel and compost on water use efficiency was significant too, and the highest WUE was 57.97kg/m3 obtain from C30G0 treatment and the lowest WUE was 15.64 kg/m3 Obtained from C0G15.The best of interval irrigation obtained from C50 treatments equal 8 days. According to the results and beneficial effects of compost on growth and yield of tomato use of compost I preparing of bedding of greenhouse tomato is recommended.

Trend of population growth and restricted resources highlights the necessity and importance of enhancing productivity of these resources. Increasing the quantity of agricultural products will be possible by increasing the area or yield of crops. In increasing the area of land, there would be limitations in water and other resources. The only way to increase the quantity of agricultural products is increasing the yield in the existing area, which is possible by promoting the inputs impacts. The aim of this study was to measure and compare the productivity of production factors in potato fields under sprinkler and furrow irrigationsystems in Kabodarahang plane. This project was performed using the stratified sampling with a questionnaire and interviewing 95 farmers. The collected data were analyzed in Cobb-Douglas production function. The results showed that in sprinkler irrigation system, the average productivity of seed and phosphate fertilizer were 10.9, 169 kg yield/kg input, respectively, and for water 6.5 kg/m3. These parameters for surface irrigation system were 9.8, 158.6 kg yield/kg input and 3 kg/m3. According to the results, in this area, the productivity of all production factors, specially water, are higher in sprinkler irrigation system. To enhance the productivity of production factors and optimal use of resources, especially water resources, it is recommended to use sprinkler irrigation in potato production.

Proper and efficient use of water and fertilizers, in addition to increasing productivity, increase crop yield. In order to study the effects of drip irrigation management and nitrogen fertilizer levels on yield of peanut, an experimen was conducted in Astaneh Ashrafiyeh, Guilan province, in 2012 and 2013 using split plot in a randomized complete block design with three replications. The main plot included water treatments consisting of no irrigation and application of 60%, 80%, and 100 percent water requirement. Sub plots included nitrogen fertilizer levels i.e. 0, 30, 60 and 90 kg.ha-1. The results showed that pod yield were similar in treatments of %80 and 100 percent crop water requirement corresponding to 2385 and 2452 kg.ha-1 in 2012. In 2013, the yields were, respectively, 2383 and 2448 kg.ha-1. The highest pod yield was obtained in 60 kg.N.ha-1 treatment in 2012 and 2013, amounting to, respectively, 2351 and 2667 kg.ha-1. Seed yields in 2012 and 2013 were obtained in 100 percent crop water requirement, with 1885 and 1877 kg.ha-1, respectively, which were significantly higher compared to the treatment without irrigation. In the fertilizer treatments, the average yield of 60 kg N.ha-1 in 2012 and 2013 was, respectively, 1829 and 2012 kg.ha-1. In water treatments, water productivity based on biomass yield varied between 1.03 and 1.68 kg.m-3 and, based on pod yield, it was observed between 0.37 and 0.63 kg.m-3, in 2012 and 2013. The water productivity values of seed yield in the 100% water requirement in the crop years 2012 and 2013 were 0.28 and 0.40 kg.m-3, respectively. Therefore, considering the results of yield and water productivity, management practice of 100% water requirement and 60 kg.N.ha-1 is the most appropriate method for peanut cultivation in the study area.

Implementation of pressurized irrigationsystems in Yazd province has faced problems in respect to farmers’ participation.This study aimed at identifying effective factors on pistachio farmers’ reluctance to adoption of pressurized irrigation. The research method usedwasdescriptiveand survey toolwas a questionnaire that was completed by interview. The target group included the pistachio farmers’ who had not reluctance in pressurized irrigation in Yazd province, and among them, 130 were selected by random sampling method. According to surveys taken from literature, effective factorson reluctance toadoption of pressurized irrigationwere divided in to technical factors, economic, social, educational,and environmental. As shown by the results,design and implementation of pressurized irrigation system, high interest rates, short duration of their repayment, pressing and obliging the farmers to the system,lake of training courses on the pressurized irrigation,and not wetting soil to the desired depth were the main reasons for the lack of interest by pistachio farmers’ to adopt pressurized irrigation. The results of the factor analysis of variables affecting this reluctance showedthat most of the special- effect was due to educational factors followed by economic factors and the technical, social and environmental were effective factors on pistachio farmers’ reluctance to adoptpressurized irrigation. The sum of these factors could explain 74.74 percent of the variance of resistance to reluctance topressurized irrigationsystems in Yazd province.

There is threat of salinizing for irrigated area in arid and semi-arid areas. Agriculture sustainability under this condition is dependent on removal of excess salt from the root zone. Although conventional drainage systems could provide suitable condition for root zone growth by removing excess water and salt, these systems face some challenges such as high initial capital, environmental problems, high volume and low quality of drained water at outlet. Alternative systems or their combination with conventional ones may be good solution for these problems. In this study, dry drainage (DD) was conducted as environmental and economical alternative technique. This research was carried out to evaluate DD and calibrate HYDRUS-2D model, in July, 2015, at Aburaihan Faculty, University of Tehran. Necessary data was collected from lysimeters in research field of irrigation and drainage Eng. Department to calibrate the model and investigate DD. Treatments were carried out in four lysimeters with dimension of 1×1×1 m and included two ratios of cultivated to uncultivated width strip (1(cultivated):1(uncultivated); and 2:1) and two levels of irrigation water salinity (1.5 and 3 dS m-1). Shallow water table was at 90 cm and study was continued for 70 days. Results showed that salt moving direction was from the irrigated to the bare evaporation strips at all treatments, and final soil salinity of uncultivated was much more than the cultivated area. Also, increasing cultivated to uncultivated width (from 1:1 to 2:1) could transport soil salinity from the irrigated to evaporation strip, but it couldn’t stabilize salinity of the root zone. Final salinity of root zone in treatments with ratio of 1:1 was not more than 6 dS m-1 (1.7 to 2.7 times of initial soil salinity).Thus, for the other two treatments, the final salinity was more than 14 dS/m (4.9 to 7.7 times the initial soil salinity). Results of modeling and statistical indexes showed that HYDRUS­_2D could simulate water flow and salinity transport well in lysimetric DD. SE and NRMSE for simulated soil moisture were between 7% to 11 percent and 0.021 to 0.057 cm3 cm-3,respectively, and these values for simulated soil salinity were between 24% to 29 percent and 2.01 to 2.73 dS m-1, respectively. Based on statistical indicators, HYDRUS_2D simulated soil moisture better than soil salinity.

Unsustainable withdrawal of agricultural water resources in the province of Kerman has caused an annual average of one-meter drop in ground watertable. Drop in groundwater levels, in addition to decreasing water resources, has caused their gradual salinization. Thus, it is necessary to carry out research to find the ways for increasing water use productivity (WUP) and new guidelines to use saline water. This research was conducted in randomized complete block design, consisting of two types of irrigation water (normal and magnetic saline water with a salinity of about 19 dS/m) and two amounts of irrigation water (85% and 100% of the water requirements of pistachio trees). Treatments were compared with a mixture of non-saline and saline water treatment as a control (with a salinity of 6.5 dS/m). Irrigation was done every 30 days, based on the irrigation frequency of the experimental plots before the project. The results showed that, in most cases, there was no significant difference (p

It is necessary to optimize productivity and usage of available water resources due to shortage of these resources and low irrigation efficiency in rice fields. In order to study the effect of different irrigation managements and planting densities on rice, cv. Hashemi, an experiment was conducted in a randomized complete block design (RCBD) with three replications at Koshal-Lahijan, in north of Iran, during cropping seasons of 2014 and 2015. There were 5 levels of irrigation treatments in this research including: I1 = Submerged irrigation, I2 = Saturation, I3 = Irrigation with 8 days interval before anthesis, I4 = Irrigation with 8 days interval after anthesis, I5= Irrigation with 8 days interval throughout the growing season). Also, there were 3 levels of planting density including, D1=15×15, D2=20×20, and D3=25×25 cm. Combined variance analysis showed that the effect of water stress and plant density on measured traits were significantly different (p

Increasing water use efficiency (WUE) is one of the most important strategies for mitigating water deficiency crisis. The aim of this study was to investigate the effect of plant competition on water use efficiency of intercropping under different moisture regimes. The experiment was a split–split-plot design with three replications. The main plot consisted of three levels of soil moisture including W1: full irrigation, W2: mild stress (irrigation on the basis of 75% W1), W3: severe stress (irrigation on the basis of 75 % W1). The subplot contained five planting patterns: fenugreek sole crop, nigella sole crop and three mixed ratios (2:1, 1:1, 1:2 of fenugreek and nigella). Results showed that the greatest WUE for seed production (WUEs) was obtained in fenugreek: nigella (1:2) treatment under drought stress conditions. Under mild stress conditions, the WUEs in fenugreek: nigella (1:2) treatment was even higher than nigella sole crop under no stress conditions, under which the highest WUE for biomass was observed in fenugreek: nigella (1:2) and (2:1) treatments and the lowest level was in nigella sole crop. The water equivalent ratio (WER) of intercropping treatments was superior to each of the sole crops of fenugreek and nigella. Under mild stress conditions, the maximum level of WER in fenugreek: nigella (1:2) and (2:1) treatments was 1.44 and 1.47, respectively. It can be concluded that interspecies competition is one of important strategies to increase the WUE and production under drought stress conditions.

Accurate identification of the potential hazards within the main Agricultural Water Conveyance and Delivery Systems (AWCDS) and their influences on the system failure could provide practical solutions for improving the operational performance of the systems. Therefore, risk analysis in AWCDS is inevitable to the system recognition and reliability endurance against the imminent hazards. Satisfactory operational of the AWCDS in irrigation networks is associated with delivery of adequate and equitable water to the entire off-takes located within the main irrigation canals. Accordingly, this study was conducted, for the first time, to present a unique framework to assess the adequacy, equity, and efficiency of water delivery risk analysis within AWCDS. To this end, the "fault tree" technique was employed for risk analysis of the disaster (hazardous event) which is called the "undesirability of supply and delivery". Consequently, factors leading to the occurrence of the failure, including natural hazards, human and operational threats as well, are recognized and formed the basic and middle events in the “fault tree" structure. The designed "fault three" was tested on the West Dez main irrigation canal, as the case study of the research. By interviewing the manager, local authorities, ditch-riders, and personnel of the Dez irrigation district, a set of questionnaires were filled up. According to the obtained information, failure probabilities of the basic events were gathered in the form of linguistic terms. Later, the assembled fault tree was analyzed and, as a result, the failure probability of the secondary events and the top event was determined. Failure likelihood of the top event was calculated at about 30%. Consequently, due to this high failure likelihood, basic events were ranked based on their share in the occurrence of the relevant secondary events as well as the top event. The five most important events were "failure to fund maintenance process", "lack of operation flexibility", "non-homogeneous operation system", "inactivity of cultural and training centers of the province" and "inaccurate operation of the intakes". The Birnbaum index of these events varied from 0.055 to 0.097. Ranking of the events affecting the adequacy, equity, and efficiency was performed, with similar results.

In order to evaluate the effect of irrigation amounts on soybean yield and quality, an expriment was conducted as randomized complete block design with three replications in Kermanshah, during summer of 2015. Irrigation treatments were in eight levels including T1=100%, T2=120%, T3= 80%, and T4=60% of crop water requirement in all growth periods, and T5= 80% and T6=60% in vegetative stage, and for T7= 80% and T8=60% water requirement was applied at flowering stage. During other stages of plant growth in T5, T6, T7, and T8, plants received 100% of water requirement. In this study, some geometric and gravity properties of seeds including length, width, area, perimeter, length to width ratio, circulatory coifficent, distance from the center of gravity to the junction of length and width, and leaf area index by using SmartGrain model and yield components, the number of pods, seed weight, dry weight, and plant height were measured and evaluated. The results showed that irrigation significantly affected all traits, except for the distance between the center of the intersection of width and length grain and circulatory coifficent. So, the most sensetive stage to water stress wass flowering, followed by the 60% water requirement treatment in the whole growth period. The highest water use efficiency for grain and oil yield was obtained in 120% treatment, followed by the 80% treatments in vegetative growth stage. In general, the results showed that, if deficit irrigation is to be carried out on soybean, it is better to have 20% irrigation deficit (80% water requirement) at the vegetative stage.

Improving water productivity and irrigation efficiency is important in Iran due to limitations in water quality and quantity. This study was conducted to investigate and analyze application efficiency and water productivity at field scale in Nazloo-Chay plain, located in Urmia province, during 2015-2016. For this purpose, five wheat fields, as fall planting, and five fields for spring crops i.e. maize and pumpkin (two fields of each) and sunflower (one farm), were studied. Irrigation system in wheat fields was border, while spring crops were furrow irrigated with closed end condition. To evaluate and measure the water productivity and irrigation efficiency in each irrigation event, some parameters were measured including irrigation depth, system geometry, soil water depletion in the root zone before irrigation (SMD) and the plant parameters. In the five wheat fields, a total of 21 irrigation events were performed and all of which were monitored and evaluated. The average of irrigation efficiency and standard deviation in the 21 irrigation events at these five wheat fields was about 30.9% and 19.5 percent, respectively. For the three spring crops, 27 irrigation events were evaluated and the overall average irrigating efficiencies for sunflower, pumpkin (cucurbita) and maize were about 69.3%, 51.5% and 52.5%, respectively. The average of standard deviation in spring plantings was calculated at about 13.9 percent, which indicates that the scattering of application efficiency was less in spring plantings than fall planting. Based on the results, the average of physical water productivity in wheat fields was 1.1 kg/m3. This index for sunflower, pumpkin (Cucurbita) seed and maize was calculated at about 0.27, 0.17 and 7.02 kg/m3, respectively. Average economic water productivity in wheat was 14512.4 Rial/ m3 and for sunflower, maize and cucurbita seed were 20252.6, 13463.9, and 23305.3 Rial/ m3, respectively, which indicated high economic water productivity for sunflower and Cucurbita seed. Generally, the crop management practices in all fall and spring plantings including fertilizer and pesticides applications were based on scientific recommendations, but irrigation management was poor in all farms. One of the main reasons for low application efficiency in these farms (in particular the fall plantings) was the poor field leveling that required high water depths for irrigation of the fields.