Research Paper
Alireza Tavakoli; Abdolmajid Liaghat; Amin Alizadeh
Abstract
Crops growth and production in rainfed systems is a function of changes in climatic parameters. Identification of the effective parameters and planning for their management and/or adapting agronomic practices to those changes will result in improving production baseline and yield prediction. In order ...
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Crops growth and production in rainfed systems is a function of changes in climatic parameters. Identification of the effective parameters and planning for their management and/or adapting agronomic practices to those changes will result in improving production baseline and yield prediction. In order to estimate climate-yield production functions, we analyzed eight crop seasons data (1998-2006) of 25 climate parameters and rainfed wheat grain yields of four cold and semi-cold regions of Lorestan province including Aleshtar, Khoram-Abad, Aligodarz, and Boroujerd. Correlation coefficients of linear and non-linear regressions were established between each weather parameter, as the independent variable, and wheat grain yield. By path analysis method, correlation coefficients were separated into direct and indirect effects. Results showed that, in local models of production functions, the role of vapor pressure deficit during crop growth was very important. Rain water productivity of all regions determined for eight crop seasons, and the amounts of maximum, minimum, and average rain water productivity were 0.341, 0.132, and 0.234 kg per cubic meter precipitation, with the average being 20 percent lower than the national average (0.292 kg.m-3). The maximum temperature of Oct-Nov, sunshine hours,, autumn precipitation, and maximum seasonal temperature were the most sensitive parameters with respect to grain yield prediction. Determination of the effective climatic factors and the degree of their effects will help farmers in adopting improved agronomic practices (such as proper planting dates, suitable cultivars, and improving soil water holding capacity), thereby controlling the negative factors affecting criop growth and yield and improving the effectiveness of the positive factors.
Research Paper
Mohammad Feizi
Abstract
Quality degradation of some water resources in arid- and semi- arid regions of Iran is a major factor limiting plant growth and agricultural production. One imperative response to this challenge is proper use of saline water for agricultural activities. The present experiment was carried out on sugar ...
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Quality degradation of some water resources in arid- and semi- arid regions of Iran is a major factor limiting plant growth and agricultural production. One imperative response to this challenge is proper use of saline water for agricultural activities. The present experiment was carried out on sugar beet in southeast of Isfahan city, Iran, and comprised a completely randomized block design, with split-split plots and four replications. In this study, three irrigation water quality treatments of 1.6, 8.1 and 12.3 dS m-1(S1, S2 and S3, respectively) were assigned to the main plots. The sub-plots contained two different water management practices:(1)irrigating with the aforementioned three water qualities during the whole irrigation period and (2)similar the first treatment but irrigation with fresh water (1.6 dSm-1) during germination and establishment stages. In the sub-sub-plots, two leaching treatments were applied consisting of no leaching (LR0) and leaching amounts of 2.6%, 14.1%, and 19.6%, for S1, S2 and S3, respectively (LR1). The results showed that salinity of irrigation water significantly reduced white sugar yield (WSY) such that S2 and S3 treatments reduced WSY, respectively, 6.7 and 10 percent compared to S1 treatment. Root yield (RY) also decreased with increasing irrigation water salinity. Application of leaching significantly increased RY, WSY, and sugar yield. Statistical analysis indicated that, with higher levels of water salinity, the amounts of Na+, K+, and α-amino-N were significantly increased. Also, the molasses sugar increased with increasing salinity. Application of fresh water during initial period of growing season reduced the effect of saline water slightly in most of the yield component traits, whereas the effect of leaching application was significant on sugar beet yield components.
Abdolamir Rahnama; Abdolhamid Mohebi; Majid Alihoori
Abstract
Due to intact and vigorous root system, tissue culture-derived date palm could establish well in the soil which, in turn, results in satisfactory vegetative growth. Low percentage fruit set and, consequently, poor yield is, however, one of the drawbacks of such plants in the early years of fruiting ...
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Due to intact and vigorous root system, tissue culture-derived date palm could establish well in the soil which, in turn, results in satisfactory vegetative growth. Low percentage fruit set and, consequently, poor yield is, however, one of the drawbacks of such plants in the early years of fruiting phase. This study aimed at increasing fruit set and yield of date palm cv. Barhi through impproving irrigation and application of fertilizers during 3 successive seasons from 2008-2010 in Ahvaz, Iran. The experiment was set up as a split-plot arranged in a randomized complete block design with irrigation intervals as the main plots and fertilizer treatments as the sub-plots, with 3 replications. Three irrigation intervals included 7, 14, and 21 days and regimes of fertilization included the control (based on soil test), 30% below the control level, and 30% above the control rate. Results showed that irrigation had significant effects on cholorophyl content and all vegetative parameters, expect leaf. No significant differences in fruiting characteristics were observed between irrigation intervals. Shorter irrigation intervals increased trunk length and diameter, chlorophyll content, number of leaf and leaflets and leaf width. Fertilizer had significant effects on chlorophyll content, leaf width, fruit set and yield. Increased rates of fertlization raised chlorophyll content and increased leaf width but decreased fruit set and yield. Interaction of fertlizer and irrigation had significant effects on all vegetative and reproductive parameters. The highest yield was obtained under 7 days irrigation interval combined with fertilization at 30% below the control (47.4 kg/tree), showing that irrigation is more influential on date yield than fertilizer application
Research Paper
Ezatollah Abbasi; Hossein Dehghanisanich
Abstract
Accurate determination of crop evapotranspiration (ETc) is an important factor in precision irrigation, irrigation planning, and water productivity. The present research aimed to study the impact of the meteorological data based (daily and long period) for calculation of ETc on apricot (Aybatan variety), ...
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Accurate determination of crop evapotranspiration (ETc) is an important factor in precision irrigation, irrigation planning, and water productivity. The present research aimed to study the impact of the meteorological data based (daily and long period) for calculation of ETc on apricot (Aybatan variety), irrigation planning and consumptive water. The study was conducted in Karaj region for two years based on randomized blocks design where three irrigation treatments (I1, I2, I3) were applied and each treatment consisted of three blocks with four replications. In I1, daily evapotranspiration was calculated based on daily weather data collected by using a µMETOS weather station system. In I2, calculation was based on long-term climatic data, and in I3, irrigation was based on farmers’ practices and was used as the control. According to the results, water use efficiency (WUE) was 3.33 kg/m3 in I1 and 1.99 and 1.29 kg/m3 in I2 and I3, respectively. Variance analysis results indicated that there was significant difference (at one percent level) in yield and WUE between the treatments and different blocks. Accordingly, comparison of the average yield and WUE by Duncan´s test indicated significant difference (at one percent level) between yield and water use efficiency of I1 and the other treatments. Indeed, in drip irrigation method, the maximum yield of apricot occurred where crop water requirement was based on daily weather data and resulted in 13% and 67% increase in, respectively, yield and WUE compared to long period weather data. It was concluded that applying real time weather data for planning irrigation management and scheduling was recommendable.
Research Paper
Horieh Bozorgan; Mohmmadhossin Mohammadi; Afshin Tavakoli
Abstract
Water uptake by plants in arid and semi-arid regions has been the subject of many investigations. Some concepts such as;" Water Use Efficiency, WUE,", "Available Water ,AW," and "Least Limiting Water Range, LLWR," have been developed to quantify knowledge of water use at field scales. Many ...
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Water uptake by plants in arid and semi-arid regions has been the subject of many investigations. Some concepts such as;" Water Use Efficiency, WUE,", "Available Water ,AW," and "Least Limiting Water Range, LLWR," have been developed to quantify knowledge of water use at field scales. Many studies have been conducted to properly delineate these concepts. In this study, we refine one of the upper limits of LLWR through studying the water uptake pattern by corn (Zea Maize) in nearly saturated soil condition. We used two soils with different textures, namely, sandy loam and clay loam, for growing corn in a greenhouse experiment. Six different matric suctions including -20, -40,-60, -80, -100, and -120 cm, were continually imposed on corn using handmade tensiometers. Daily evapotranspiration, total water consumption, dry matter of shoot, and WUE were measured during 2009-2011. The maximum WUE was obtained at matric suction of -60 cm and -80 cm for sandy loam and clay loam soils, respectively. Further analysis showed that these suction heads corresponded to aeration porosity of 0.04 and 0.06. We suggested that the maximum soil moisture content supplying the max yield, can be considered as the critical aeration porosity. Consequently, we conclude that the suction heads of -60cm and -80 cm for sandy loam and clay loam soils are one of the upper limits of LLWR for corn. These limits may be applied for more appropriate modeling of irrigation schedules at large field scales.
Masoud Mohammadi; Hossin Molavi; Abdolmajid Liaghat; Masoud Parsinejad
Abstract
Salinity and water stress are the main problems of agricultural production in many parts of the world, especially in arid and semi-arid areas. Therefore, this study was conducted to investigate the effects of Zeolite application under salinity and ...
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Salinity and water stress are the main problems of agricultural production in many parts of the world, especially in arid and semi-arid areas. Therefore, this study was conducted to investigate the effects of Zeolite application under salinity and water stress conditions on yield and yield components of Corn in Karaj, Iran. A factorial design with randomized complete block arrangement was used with three replications including three factors: salinity, irrigation water, and Zeolite application. Irrigation water, salinity and Zeolite application factors consisted of two levels each:W1=100% and W2=50% of crop water requirement; S1=0.7, S2=5 dS/m, and Z1=0 and Z2=10 t/ha, respectively. The soil texture was clay loam. Results showed that salinity and water stresses reduced yield and yield components, while Zeolite application increased them. Simultaneous impact of salinity, deficit irrigation, and Zeolite application had significant effect on corn yield, the 1000 kernels weight, number of grains per ear, and plant height. The maximum corn yield, 1000 seeds weight, number of grains per ear, and plant height were, respectively, 7233.3 kg/ha, 309 g, 504, and 220.7 cm and corresponded to W1S1Z2 treatment, while the minimum corn yield, 1000 seeds weight, number of grains per ear and plant height were 2296 kg/ha, 101.7 g, 159, and 146.3 cm, respectively, and belonged to W2S2Z1 treatment. The maximum water use efficiency (1.41 kg/m3) and its minimum (0.68 kg/m3) were observed in W2S1Z2 and W1S2Z1 treatments, respectively.
Mehdi Akbari
Abstract
Cropped area, cropping pattern, and cropping intensity are among the most important information needed for determining the water requirements in a basin or at an irrigation scheme scale, and they are difficult to measure. Conventional methods are very local, ranging from region- to field-scale. Estimates ...
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Cropped area, cropping pattern, and cropping intensity are among the most important information needed for determining the water requirements in a basin or at an irrigation scheme scale, and they are difficult to measure. Conventional methods are very local, ranging from region- to field-scale. Estimates of such information over an entire area, especially for irrigated areas, are essential, as these can differ substantially depending on the cropping pattern and the management applied. Today, actual cropped area, cropping pattern and intensity under different conditions can be estimated by using satellites and remote sensing (RS) techniques. In order to obtain the required data, it was attempted to upscale the accuracy of NOAA satellite images by using Landsat 7 images. From a time series of NOAA images during one growing season, NDVI and SAVI indicators were established. Based on these indicators the actual cropped area and cropping intensities were evaluated for each irrigation network in the Zayandeh Rud basin. Results indicated that the actual cropped area using RS data was more than the designed command area in most irrigation districts of Zayandeh Rud. The designed command areas for Nekouabad-Right and Abshar-Right are 13,500 and 15,000 ha, while the actual cropped areas are 16,700 and 16,250 ha, respectively. Cropped area of Nekouabad and Abshar irrigation networks are between 72% and 81%, but cropping intensities can be much higher as an extensive area is used to grow two crops per season. Main winter crops are wheat and barley, summer crops are rice and vegetables. The main advantage of RS approach applied here is that it is nonspecific and can be easily adapted to other conditions in terms of soil, weather, and crop. Besides the benefits of this non-specific approach, the methodology applied here gives a wealth of information in comparison to field surveys, in terms of spatial and temporal resolution, and it overcomes the difficulties of field work.
Parisa Shahinrokhsar; Mohammadsmaeil Asadi
Abstract
Among the main causes of low water use efficiency are use of an improper irrigation method and applying excessive irrigation. To evaluate tape and furrow irrigation methods for soybean cultivation under different irrigation regimes, a field experiment was conducted in two years (2006-2007) at Gorgan ...
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Among the main causes of low water use efficiency are use of an improper irrigation method and applying excessive irrigation. To evaluate tape and furrow irrigation methods for soybean cultivation under different irrigation regimes, a field experiment was conducted in two years (2006-2007) at Gorgan Agricultural Research Station located in Golestan province in north of Iran. The experiment was laid out in a split plot design in the form of completely randomized blocks where each treatment was replicated three times. Irrigation systems of tape and furrow were set up as the main plots, and three irrigation regimes of 100%, 75% and 50% of total crop water requirement were allocated to the subplots. Comparison of water consumption (m3/ha) between the two systems showed that tape irrigation had 33 percent less water use than furrow irrigation. Results indicated that the soybean yield was not affected by irrigation systems. But, the different irrigation regimens had some impact on crop yield. Water use efficiency in the full irrigation (100 %) regime under drip tape irrigation was 1.6 times that of furrow irrigation system. In tape irrigation, mean water distribution uniformity (Ed) in full irrigation was 96% and in furrow irrigation it was 95%. Application efficiency (Ea) under tape irrigation was 84%, which was much higher than furrow irrigation. Also, based on the results, most of water losses in furrow irrigation systems were due to surface run off, while these losses were not observed in the tape irrigation. Overall, in drip tape irrigation, less water was consumed and water use efficiency increased compared to furrow irrigation
Jafar Mamizadeh; Zia Azizbeygi
Abstract
Backfill and backfill material supply in irrigation and drainage projects is very important in terms of technical feasibility and economics. In Eynekhosh-Fakeh pipelines project, with 230 km of GRP pipes, provision of the volume of soil for backfill around the tube is a challenge. GRP pipes are made ...
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Backfill and backfill material supply in irrigation and drainage projects is very important in terms of technical feasibility and economics. In Eynekhosh-Fakeh pipelines project, with 230 km of GRP pipes, provision of the volume of soil for backfill around the tube is a challenge. GRP pipes are made of fiberglass and are fragile and, therefore, selection of proper backfill, particularly for the lower layers, is very important. In this study, given the abundance of native sand material in the area, these materials were used around the pipes and compacted in separate experiments such as standard proctor compaction and flooding method. Results showed that materials with less than 12 percent fine grains of sand can be compacted up to 85 percent with flooding method, spending less time and achieving high work efficiency. In another part of this research, mixing of clay materials with sand, in order to provide the depth of the trenches for backfill, was studied. Analysis showed that adding sand materials to clay materials increased the density and reduced the percentage of various compounds such as gypsum, chlorine, and sulfate. Also, according to the soil plasticity index (PI) and density, quality of this mixture is suitable for backfill.
Iraj Arsalani; Mohammadreza Afshariazad; Atoosa Bigdeli
Abstract
The atmospheric precipitation through and evaporation of water from surface waters of oceans, seas, lakes, and other water bodies are in balance through... Can be, Hhydrological cycle is a balance mode. Regional Oobservations indicate of that rainfall in the regional says that rainfall changes ...
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The atmospheric precipitation through and evaporation of water from surface waters of oceans, seas, lakes, and other water bodies are in balance through... Can be, Hhydrological cycle is a balance mode. Regional Oobservations indicate of that rainfall in the regional says that rainfall changes in various years, Furthermoreconsequently, the rainfall becomes runoff, which can also be variable.
The aim of this research, was to study and analyzesis of the Anzali Wetland basin water balance in the height highlands of the mountains, where there being a lack of hydrometric stations are lacknig in some watersheds. Therefore, using empirical models (S.C.S) were used to evaluate water resources has been throughand gather the necessary knowledge concerning surplus water resources of the area and find out whether there is surplus or shortage of wateror maybe it should be the shortage.
In this study, using digital topographical maps (for purvey digital elevation model), soil maps, and data from the meteorological station within the basin and some neighboring ofstations on that neighbor confine within the layer of precipitation, evaporation, and infiltration of rainwater into the soil, for the region with the raster data layers were obtained. And theBy overlaying of this information in the GIS software, Wwater balance in the distribution of wetland elevations basin highlandsover a period of 25 years, were reviewed and analyzed over a period of 25 years.
For determining the water balance, wWater balance status of the individual parameters effluence affecting balance equation in this study are based on and included precipitation, evapotranspiration, and surface water runoff and will bewere studied within. After investigation and determination of these parameters, the information was used in the GIS environment, as GIS data layers. becomes , In this form, tThe structure of this region consisted ofas well as similar cells and haswith little value todependence on information is the information layer. Then, using the SCS method, runoff is was measured in the study area. Curve Number (or CN, where the) maps, of obtained from land combining land maps with hydrologic soil groups, and were used can be for Mmapping the water retention coefficient. (S) In addition, was side other hand with using data of the local meteorological stations, the trend in rainfall and evapotranspiration was analyzed over a period of 25 years was prepared.
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The results of this study indicated that the average annual total volume of the inputinflow in over the 1789.8 km2 area of the basin, during the 25-year period were was 25 times 2319.2 million cubic meters, while the annual output outflow stream (Total i.e. evapotranspiration and plus runoff,) was equal to 3397.5 million cubic meters, indicating a negative trend is that in some areas of the southern highlands of the basin, a trend has been negative.