Irrigation
S. JafarNodeh; A. Soltani; E. Soltani; A. Dadrasi; S. Rahban
Abstract
IntroductionAccurate knowledge of water balance components is necessary to optimize water consumption in agriculture. On the other hand, measuring water balance components is expensive and difficult. Therefore, the use of models that can simulate water balance values is important for water management ...
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IntroductionAccurate knowledge of water balance components is necessary to optimize water consumption in agriculture. On the other hand, measuring water balance components is expensive and difficult. Therefore, the use of models that can simulate water balance values is important for water management in agriculture and water used by plants. Crop simulation models have been turned into essential tools for studying plant production systems. In the SSM-iCrop2 models, it is presumed that diseases and weeds are optimally managed and will not affect growth and yield. Additionally, except in cases where the model accounts for specific nutrients such as nitrogen, it is generally assumed that nutrient deficiencies are eliminated through fertilization. Therefore, parameterized and evaluated models are designed to fit these conditions. These factors are present in the field and affect crop growth and yield as well as water use. However, in several cases it is required to estimate yield and water balance components and irrigation water volume under grower conditions. Naturally, models parameterized using experiments are unable to simulate these conditions. Therefore, a model must be prepared so that it can simulate the real conditions of farmers. In this study, the SSM-iCrop2 model has been calibrated for the real conditions of farmers, and the purpose of this study is to use the SSM-iCrop2 model in simulating water performance and water balance for farmers. Materials and MethodsIn this study, the SSM-iCrop2 model was calibrated for farmers conditions using variables such as yield and harvest index, which are available for farmers’fields or are cheap to measure. The effect of factors such as pests and diseases, weeds and unsuitable nutrients, density and sowing date entered the model along with the calibration of three parameters of radiation use efficiency, maximum leaf area and maximum harvest index for farmers’ fields. Calibration was done by comparing the performance of farmers against the performance simulated by the model and by changing the parameters of radiation use efficiency (IRUE), maximum leaf area (LAIMX) and maximum harvest index (HIMAX). This calibration was done at Hashem Abad station in Gorgan for irrigated rice (paddy) and wheat. The simulated actual yield was calibrated with the actual yield. Due to the acceptable simulation of actual yields after calibration, it was presumed that other estimates made by the model are also reliable. Results and DiscussionMeasurement of water balance and other estimates of the model from growth and yield formation in the grower fields is expensive, but a calibrated model can estimate them at a low cost. In this study, it was shown that with the model calibrated for farmers' conditions, not other easily measured information (such as the irrigation water volume) can be obtained, with the assumption that the model accurately captures this information as well as performance. To evaluate the simulated real performance model, it was compared with the actual performance of farmers (Agricultural Jihad Report) after calibration. In addition to phenology, the SSM model simulates traits related to growth and yield, evapotranspiration values, irrigation water volume, runoff, available soil water during planting and harvesting, cumulative drainage, etc. The output of the model shows the amount of irrigation water is needed for a certain amount of performance in a given place (with specified rainfall and transpiration). The irrigation water volume calculated by the model was compared with the results of field tests from previous studies conducted by researchers at agricultural research centers. It was found that the model's output and the observed values were in good agreement. The root mean square error for rice and wheat was 216.6 and 157.6 kg per hectare, respectively, and the coefficient of variation and correlation coefficient were 4 and 85% for rice and 3 and 94% for wheat, respectively. Then, the irrigation water volume estimated by the model was evaluated and validated with the measured irrigation water volume in different crops (in Golestan province for different years). Based on the results of the evaluation, the coefficient of variation and the correlation coefficient for the simulated irrigation water volume were 8.9 and 98%, respectively, compared with the observed value. This calibration was done for rice (paddy) and irrigated wheat in the fields of Gorgan town, and the simulation and running were done using the meteorological statistics recorded in Hashem Abad weather station, Gorgan. Noting the fact that the actual yield has been simulated with good accuracy after the calibration, it was assumed that the other estimates of the model are also reliable. Thus, the calibrated model estimates them with low cost and appropriate accuracy and can complement field experiments. ConclusionThis study discovered that the SSM_iCrop2 model, when calibrated for the conditions of farmers' fields, can accurately simulate both growth and yield traits as well as water balance characteristics. Notably, the model provides reliable estimates of irrigation water volume in farming scenarios, a crucial factor for agricultural planning and drought adaptation.
Irrigation
A.H. Jalali; H. Salemi
Abstract
IntroductionCumin (Cuminum cyminum L.) is an annual and herbaceous plant, with a vertical, round, narrow and branched stem, with a height of approximately 30-60 cm. This plant belongs to the Apiaceae family. This family is known for having plants with aromatic taste. Iran and some countries along the ...
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IntroductionCumin (Cuminum cyminum L.) is an annual and herbaceous plant, with a vertical, round, narrow and branched stem, with a height of approximately 30-60 cm. This plant belongs to the Apiaceae family. This family is known for having plants with aromatic taste. Iran and some countries along the Mediterranean Sea are known as the primary origin for the cumin plant. In addition to Iran, cumin is cultivated in many countries such as Uzbekistan, Tajikistan, Turkey, Morocco, India, Syria, Mexico and Chile. About 300,000 tons of cumin seeds are produced in the world annually, of which China and Asian countries produce 70% and consume 90%. Short growing season (100 to 120 days), low water requirement and the possibility of rained cultivation, non-interference between cultivation and harvesting with other crops and no price fluctuation and proper economic justification are among the factors that interest farmers in cultivating this plant. In different regions, yields of 350 to more than 1000 kg of seeds are obtained from this plant, and 3350 cubic meters of pure water are needed for production. Materials and MethodsThis research was conducted in 2015 to 2017. The first year of the study included the collection and analysis of long-term climatic data of the region, and the second year included the implementation phase of the research. Analyzing meteorological data on the scale of decades and the cases of temperature, precipitation, wind speed, sunshine hours, relative humidity and evaporation from the pan were considered as criteria and by preparing the gradient equations, the rate of reference evaporation and transpiration was calculated. The required statistical information was obtained from 28 synoptic meteorological and climatology stations in Isfahan and some neighboring provinces. In the studies related to soil, apparent specific gravity and volumetric moisture content (field capacity and wilting point), soil salinity, soil texture and agricultural ability class of land in cultivation areas were considered. Soil-related information was used to calculate the soil evaporation coefficient (Ke), which describes the evaporation component in the trait (ETc). In fact, Ke is the basis for calculating the coefficient of reduction of evaporation from the surface layer (Kr) and the fraction of soil wet and exposed to air (few), and for its calculation, the presence of information related to soil characteristics is necessary. To calculate the soil characteristics, in addition to sampling from the fields in the research, the database of 1600 soil profiles in the soil and water research department of Isfahan province was also used. Results and DiscussionThe results showed that 18 cities in Isfahan province had cumin cultivation potential, which had a significant difference in terms of pure water requirement per hectare (5% level) and water consumption at different phenological stages (1% statistical level). In terms of water requirement per hectare, the cities of Isfahan province can be divided into three groups. Average water requirement per hectare in the first group (the cities of Golpayegan, Lenjan, Tiran and Karvan, Shahin and Shahr and Mime), the second group (the cities of Isfahan, Khomeini Shahr, Falavarjan, Shahreza, Kashan, Najaf Abad, Natanz), Mobarake, Dehaghan and Borkhar), and the third group (Aran and Bidgol, Ardestan, Khoor and Biabanak and Nain) were equal to 3000, 3240 and 3770 m-3 ha-1, respectively. The water requirement of the growth development stage in the cities of the third group was equal to 2029 m-3 ha-1, which was significantly different from the cities of the first and second groups (p < 1% level). According to the results, cumin might be a suitable plant for crop rotations in Isfahan province due to its low water requirement and tolerance to moisture stress. ConclusionThe water requirement for cultivating cumin in various regions of the province is notably lower compared to many common crops, such as wheat, barley, and safflower. In 10 out of the 18 cities included in the study, significant water savings of up to 3,240 cubic meters per hectare can be achieved by optimizing water transfer efficiency. For cumin cultivation, this water conservation can even reach 3,000 cubic meters in cities with cooler climates. Surprisingly, in the hot areas of Isfahan province, including Ardestan, Nain, Khoor, Biabanak, Aran, and Bidgol, it is feasible to grow cumin with a water consumption of just 3,770 cubic meters per hectare.
Irrigation
M.R. Emdad; A. Tafteh; N.A. Ebrahimipak
Abstract
Introduction
Quinoa (Chenopodium quinoa) is native plant in Bolivia, Chile and Peru, which is widely adapted to different climatic conditions and can grow in all soils. This plant has shown adequate adaptation to arid and semi-arid areas conditions and is planted from areas with low elevation ...
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Introduction
Quinoa (Chenopodium quinoa) is native plant in Bolivia, Chile and Peru, which is widely adapted to different climatic conditions and can grow in all soils. This plant has shown adequate adaptation to arid and semi-arid areas conditions and is planted from areas with low elevation (sea level) to areas with an altitude of 4000 meters above sea level. Quinoa is often cultivated in areas with limited water resources, and it is rare to find quinoa cultivation under full irrigation conditions. Some studies have shown that quinoa yields slightly better under full irrigation (without water restriction) than quinoa under deficit irrigation. Crop growth models are very important tools in the study of agricultural systems and they can be used to simulate the yield of crop in different conditions. Given that the study of performance limiting factors requires numerous and costly research and experiments in different areas, so finding a way to reduce the number, time and cost of these experiments is worthwhile. Aquacrop model is one of the applied models that are used to simulate yield variations in different water and soil management.
Materials and Methods
This investigation was carried out in two growing seasons of 2019 and 2020 to determine the efficiency of Aquacrop model for simulating Quinoa grain yield and biomass under imposing three stress treatments of 30, 50 and 70% of water consumption in development and mid-growth stages. Plant spacing was 40 cm between rows and 7 cm between plants within rows. Seeds of quinoa (Titicaca cultivar) were cultivated in the first decade of August 2019 and in the third decade of July 2020. The experiment was a randomized complete block design with three replications. Three deficit irrigation treatments including 30, 50 and 70% of available water were considered in two growth stages (development and mid-growth) in 18 experimental plots (3 × 4 m). Soil moisture in rooting depth (about 40 cm) was measured by TDR and after the soil moisture of the treatments reached the desired values, plots were irrigated until the soil moisture reached the field capacity. The results of grain and biomass yield in the first year were used to calibrate the Aquacrop model and the results of the second year were used to validate the model. Root mean square error (RMSE), normalized root mean square error (NRMSE), Willmott index (D), model efficiency (EF) and mean error deviation (MBE) were used to compare the simulated and observed values.
Results and Discussion
The results of the first and second year were used to calibrate and validate the model, respectively. The results of the first year showed that irrigation with 50 and 70% of available water in the development stage reduced quinoa grain yield by 17 and 33%, respectively, compared to the control treatment. The application of these two deficit irrigation treatments in the middle stage reduced the yield by about 12 and 28%, respectively. The results of comparing the statistical indices of grain yield, biomass and water use efficiency showed that the NRMSE for grain, biomass and water use efficiency were 9, 8 and 14% in the first year and 9, 6 and 9% in the second years. Furthermore, the EF for these traits were 0.81, 0.77 and 0.64 in the first year and 0.68, 0.71 and 0.62, in the second year, respectively.
Conclusion
The results of calibration and validation of the model showed the accuracy and efficiency of the Aquacrop model in simulating grain yield, biomass and water use efficiency of quinoa. This model can be used to provide the most appropriate scenario and irrigation management for different levels of deficit irrigation managements.
Irrigation
N. Salamati; A. Danaie; V. Yaaghoobi
Abstract
Introduction Drought stress is the most important environmental factor limiting growth and development of plants worldwide. Growth reduction due to drought stress has been reported more than other environmental stresses. So far, many studies have been conducted on the relationship and correlation ...
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Introduction Drought stress is the most important environmental factor limiting growth and development of plants worldwide. Growth reduction due to drought stress has been reported more than other environmental stresses. So far, many studies have been conducted on the relationship and correlation between important agronomic traits in rapeseed, which have introduced 1000-grain weight, number of seeds per pod and number of pods per plant as the most important traits with high correlation in yield. The results showed that the application of drought stress had an effect on the yield components of sesame and the cultivars that were more sensitive to drought stress had a greater decrease in their yield. The aims of this study were to investigate (1) the effect of consumed water volume as the independent variable on other variables of the study, and (2) the effect of total independent variables (yield components and other independent factors) on yield and water productivity (dependent variables). Finally, the most important independent variables affecting water productivity and the most sensitive variables to the amount of consumed water were determined.Materials and MethodsIn order to achieve aforementioned objectives of this study, an experiment was conducted during two growing season of 2011-2011 and 2010-2011 in Behbahan Agricultural Research Station. The experiment was conducted as randomized complete block design with 4 replications. The applied amount of water in drip irrigation was composed of four levels of 50, 75, 100 and 125% water requirement in main plots and two canola varieties Hyola 401 and RGS003 in sub plots were placed.Results and Discussion The results of the analysis of variance of the regression model showed that the higher absolute value of beta coefficients and t-statistic of each independent variable caused that variable to be introduced as the most sensitive independent variable affecting the dependent variable. Therefore, the independent variable of water volume, with beta coefficient of 0.860 and t-statistic of 13.246 had the greatest effect on plant height variable. In terms of yield, the studied variables (the number of pods per plant, the number of seeds per pod, and 1000-seed weight, consumed water volume, flowering period, growth period and plant height) showed 74.1% of variation (R2 = 0.741) of dependent variable (Yield of canola). The consumed water volume with the highest absolute value of beta coefficient of 0.563 and t-statistic with 2.967 had the most significant effect on yield at the level of 1%. Among the dependent variables, the consumed water volume with the highest absolute value of beta -1.013 and t-statistic at -12.415 had the most significant effect on water productivity at the level of 1%. consumed of water volume with the highest absolute value of beta coefficient of 0.563 and t-statistic with 2.967 had the most significant effect on performance at the level of 1%. The results of Pearson correlation coefficient showed that the highest correlation between the number of pods per plant and seed per pod with both plant height were calculated to be 0.763 and 0.849, respectively, indicating that increasing plant height was effective in increasing the number of pods per plant and seed per pod.ConclusionThe results of analysis of variance of regression model showed the effect on volume of consumed water as an dependent variable through other variables (number of pods per plant, number of seeds per pod, yield, water productivity, 1000-seed weight, flowering period, growth period and plant height). Results showed a significant effect of all variables at the level of 1%, except for the variable of flowering period which had a significant effect but just at 5%. The volume of consumed water by r= 66.2% on grain yield variation in the pods, had the most significant effect on yield components. Therefore, seed number in the pods received the most negative effect from reducing water consumption due to drought stress. With increasing the growth period of canola, water productivity showed a significant decrease at 1%. The results of Pearson correlation coefficient showed that grain water productivity had a negative and significant correlation at the level of 1% with all variables. The highest correlation between water productivity (r = -0.939) was calculated with volume of consumed water, which indicates the importance of reducing water consumption in increasing canola water productivity.
Irrigation
E. Asadi Oskouei; S. Kouzegaran; M.R. Yazdani; A. Rahmani
Abstract
Introduction: Correct assessment of evapotranspiration fluctuations in different meteorological scenarios plays an important role in the optimal management of water resources. Probability analyzes with different probabilities of occurrence can increase flexibility in decision making and increase the ...
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Introduction: Correct assessment of evapotranspiration fluctuations in different meteorological scenarios plays an important role in the optimal management of water resources. Probability analyzes with different probabilities of occurrence can increase flexibility in decision making and increase the reliability of decisions. Rice (Oryza sativa L.) is one of the most important agricultural products in the world. Although rice is cultivated in a wide range of climatic and geographical conditions, it is vulnerable to changes in environmental conditions. Planting management, design of irrigation systems, and suitable irrigation cycle for optimal production are important issues for sustainable production.
Materials and Methods: The study area includes the northern region of Iran, i.e. the provinces of Gilan, Mazandaran and Golestan, which is the main rice-growing area in Iran. Changes in rice evapotranspiration in three different cultivation dates with four different occurrence probabilities of 75, 50, 25 and 10%, was calculated using the FAO Penman-Monteith equation and meteorological data with a statistical period of 30 years (2020- 1990). Also, the average rice crop coefficient at different stages of growth in 10-day periods was estimated based on the Weibull model. These probabilities represent the probable limits of the expected values of evapotranspiration in different scenarios of low, normal, high, and very high evapotranspiration years.
Results and Discussion: The results showed a relatively constant difference of 1 to 2 mm between different rice cultivation histories in the major rice cultivation areas of Gilan and Mazandaran in normal to very high evapotranspiration years. In the years of low evapotranspiration, the water requirement was significantly different from the normal, high and very high evapotranspiration years, which decreased from east to west. This difference was approximately 30% higher in Golestan province as compared with other areas. In the early planting situation relative to the late planting situation in the major western and central coastal areas, there was a 10% decrease in water consumption. At the scale of the whole growing season in Gorgan, evapotranspiration in different conditions of planting date was on average 20% (1300 cubic meters) more than the main regions of Gilan and Mazandaran. In case of timely planting, the net irrigation requirement in very high evapotranspiration years was about 2000 cubic meters per hectare more than the normal years. In years with high evapotranspiration, late planting increased the net irrigation requirement by more than 210 mm compared to different planting dates in Gorgan. According to the obtained results, the largest difference between evapotranspiration values during normal and very high evapotranspiration years was in the late planting situation. Therefore, it seems that late planting causes a significant increase in water consumption in the high evapotranspiration years. Consequently, it is better to avoid rice cultivation when the rice growing season is anticipated to be warm.
Conclusion: Evapotranspiration, as one of the main components of the hydrological cycle, had a significant role in proper irrigation planning and water resources management. The results underline the importance of estimating the rice evapotranspiration to avoid appreciable yield loss under extreme conditions.
R. Saeidi; H. Ramezani Etedali; A. Sotoodehnia; .B Nazari; A. Kaviani
Abstract
Introduction: Supplying human and animal nutritional needs requires suitable use of water resources. Due to the decrease of fresh water resources for agriculture, saline water resources cannot be ignored. Increasing water salinity reduces the water absorption by plant, due to decreasing the water potential. ...
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Introduction: Supplying human and animal nutritional needs requires suitable use of water resources. Due to the decrease of fresh water resources for agriculture, saline water resources cannot be ignored. Increasing water salinity reduces the water absorption by plant, due to decreasing the water potential. On the other hand, soil infertility (such as nitrogen deficiency) decreases the evapotranspiration and crop yield. The present study was to increase the water and nitrogen fertilizer use efficiency of maize, under salinity stress condition. This was done by managing the consumption of saline water and nitrogen fertilizer. In this research, irrigation requirement was determined proportional to the plant evapotranspiration to avoid excessive saline water use. Materials and Methods: In this research, two treatments of water salinity and nitrogen deficiency in four levels and three replications were implemented as a factorial experiment in a randomized complete block design. The studied plant was maize (S. C. 704 cultivar) sown in plots with dimensions of 3 × 3 meters and 1.5 meters distance. In this research, fertility stress was in the form of nitrogen fertilizer consumption and at four levels. Treatments of ، ، and consisted of consumption of 100, 75, 50 and 25% of nitrogen fertilizer, respectively. Salinity stress has been applied by irrigation of the plant with saline water. Water salinity treatments were selected based on the yield potential of maize, at four levels of 100, 90, 75 and 50%. According to the above four performance levels, treatments of ، ، and included irrigation water with electric conductivity of 0.5, 1.2, 3.5 and 7.5 (dS/m), respectively. The soil moisture content was measured at the depth of root development during the interval between two irrigations. Daily maize evapotranspiration was measured by the volumetric balance of water at the depth of root development. The stomata resistance of maize leaf was measured by the AP4 porometer device between two irrigations interval. Variance analysis and mean comparison of data were done by SPSS software and Duncan's multiple range test, respectively. Results and Discussion: Water use efficiency In this research, the evapotranspiration and dry matter yield of maize decreased under salinity stress and nitrogen deficiency treatments. This seems to be caused by the water potential decrease (due to salinity stress) and the nitrogen deficit in the soil. Under these conditions, optimum use of water and fertilizer increased water use efficiency. At first without water and fertilizer management, water use efficiency in different treatments ( to ), ranged from 2.74 to 4.4 kg/ (in 2017) and from 2.57 to 4.35 kg/ (in 2018). With suitable management of irrigation, water use efficiency, however, increased in stress treatments and approached to optimum treatment. The range of water use efficiency was from 4.2 to 4.4 kg/ (in 2017) and from 4.15 to 4.32 kg/ (in 2018). The reason for this was the management of irrigation volume based on actual evapotranspiration in stress treatments. On the other hand, increasing soil nitrogen was an appropriate strategy to increase water use efficiency. But in high salinity stress, despite the optimum use of water and fertilizer, it was not possible to achieve optimal water use efficiency. This is explainable by the harmful effect of salinity on the reduction of nutrient uptake (especially nitrogen) by the plant. Nitrogen use efficiency Soil nitrogen deficiency and increasing water salinity reduced nitrogen use efficiency. In different stress treatments, nitrogen use efficiency ranged from 3.34 to 5.11 kg/kg (in 2017) and from 3.06 to 5 kg/kg (in 2018). The results showed the destructive effect of salinity on nitrogen uptake by the plant. Under these conditions, the ions in the soil (especially the sodium and calcium) caused the plant to be unable to absorb nitrogen from the soil. Therefore, the production of plant matter was reduced. The results showed that proper management of nitrogen can increase nitrogen use efficiency under salinity stress. At high salinity levels, the nitrogen fertilizer was not, however, absorbed by the plant and accumulated in the soil. Conclusion: The results showed that water use management could increase the water use efficiency under stress treatments, by controlling evapotranspiration. On the other hand, soil fertility increased nitrogen fertilizer use efficiency under salinity stress. Among all treatments, had optimum water and nitrogen use efficiency. Overall, the volume of water used in the field should be adjusted to the actual requirement of the plant to prevent excessive consumption under salinity stress. In addition, increasing soil nitrogen, rather than more irrigation water, appears to be a suitable strategy to increase crop yield.
S. Tofigh; D. Rahimi; H. Yazadnpanah
Abstract
Introduction Statistical models and numerical simulations have been widely used to detect relationships between the climate and crops. However, the influence of non-climatic factors (such as cultivar and fertilizer changes on yield crop needs to be eliminated. For this reason, dynamic crop models ...
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Introduction Statistical models and numerical simulations have been widely used to detect relationships between the climate and crops. However, the influence of non-climatic factors (such as cultivar and fertilizer changes on yield crop needs to be eliminated. For this reason, dynamic crop models include the SUCROS, Erosion Productivity Impact Calculator(EPIC), WOrld FOod STudies (WOFOST), Agricultural Production Systems sIMulator (APSIM), and Decision Support System for Agrotechnology Transfer (DSSAT) have been used in water, nitrogen and weather responses. Among these models DSSAT contains separate models for different crops and can quantitatively predict the growth and production of the annual field crops.
Materials and Methods: In this study, the data of Shahrekord Agricultural Meteorological Station and the data of Lysimeter Station were used to evaluate the correlation between the research results and Lysimeter data from Pearson correlation coefficient, and the RMSE, MAD and MSE are applied in order to calculate the error.
Results and Discussion: Lysimeter: The wheat evapotranspiration amount from the planting (20 of Octobers) to the harvest time (14 of July) is recorded as 611.24 mm. Precipitation during the winter is low but continuous and it is 127 mm that equivalent to the evapotranspiration at this time of growth. In the warm season, a quarter of the evapotranspiration is provided by rainfall. The average of winter evapotranspiration is 0.87 mm per day and in the growth season is 4 mm per day. Also from planting to harvest is 2.42 mm per day that is recorded its maximum 7.8 mm and its minimum 2.32 mm per day. The total amount of drained water during the growth is 76.04 mm that 8.8% of the total rainfall. It indicates that drainage water from the soil is low and irrigation has a high efficiency.
CERES-WHEAT: Wheat evapotranspiration amount during the growth period is 413.51 mm by FAO Penman-Monteith and 489.53 mm by Priestley-Taylor. Precipitation during the winter is low but continuous and it is 127 mm that equivalent to the evapotranspiration at this time of growth. In the warm season, a quarter of the evapotranspiration volume is provided through rainfall. The average of winter evapotranspiration based on the F.P.M and P.T methods are 0.86 and 1.23 mm/day and in the growing season 2.98 and 3.11 mm/day, respectively. During the experiment, the evapotranspiration average is 1.59 mm/day for the FPM method that the maximum is 6.61, and the minimum is 0.379 mm/day. This amount is 1.88 mm/day for P.T method which the maximum is 5.64 and the minimum is 0.45 mm per day. The total amount of drained water during the growing period is 106.3 mm, based on the F.P.M method and 90.2 mm based on the P.T method.
The correlation between farm data and the data obtained through the F.P.M method of CERES-Wheat model is 0.97, which for the P.T method is 0.92. The MAD, MSE and RMSE values obtained between the F.P.M method and farm data are 0.95, 0.95 and 1.57, respectively, and for the P.T method, 0.97, 1.47 and 1.21, respectively. With respect to correlation and MAD, MSE and RMSE value, it is found that the model is highly capable in simulating evapotranspiration and crop performance. Among the methods applied in determining evapotranspiration, the F.P.M method with high correlation and lower error value is more accurate than the P.T method.
Water Factor: From the day 177 to 216 is considered the most sensitive stage of plant growth. Based on DSSAT output over a 25-day period (196 to 216 days) the water available is severely depleted and the plant may experience drought stress. At this stage of the growth, water deficiency should be offset by increasing the time and the amount of irrigation.
Day 210 is the beginning time of the increase in evapotranspiration of the plant. During this period, the amount of water which is uptake from the soil was less than 1 time the plant demand. This period of stress was based on the FAO Penman- Monteith method between the 203rd and 210th days. During this period, the plant goes through its clustering and flowering stages, and water stress at this stage causes the growth of wrinkled and lean grain, resulting in reduced grain weight and reduced crop yield. Water scarcity must be compensate by increased irrigation.
Conclusion: Comparison of model calibration results and farm data indicates that there is a high correlation between farm data and model output. The error between the model results and the Lysimeter station data is low. Among the methods used to calculate the evapotranspiration in the model, FAO Penman- Monteith method is the highest correlation and the lowest error value with the farm experiments and results. In general, the results indicated that the CERES-Wheat model has a high ability to simulate evapotranspiration and wheat yield. Regarding observed data for crop irrigation program indicates that farmers' performance in managing the amount of water needed for the crop at various stages of the growth was not optimal. Consequently, drought stress was observed for developmental and mid-growth stages. The DSSAT simulation indicated that the optimal irrigation management adjusts the time and value of irrigation water according the actual evapotranspiration and water requirement would significantly improve irrigation water use.
R. Najafipour; H. Ramezani Etedali; B. Nazari
Abstract
Introduction: Greenhouses have a key role in agriculture productions. Given the ability of controlling production factors, there is the possibility of out-of-season cultivation in greenhouses, which is important in terms of food security, economics, and agricultural marketing. Estimation of water requirement ...
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Introduction: Greenhouses have a key role in agriculture productions. Given the ability of controlling production factors, there is the possibility of out-of-season cultivation in greenhouses, which is important in terms of food security, economics, and agricultural marketing. Estimation of water requirement for planning the development of greenhouses and their operation is very important. Awareness of the exact amount of water requirement is important both in terms of production and growth. Many studies have shown the usefulness of greenhouses in improving yield, physical and economical productivity. So far, comprehensive studies have not been carried out on the productivity of greenhouse cucumber cultivation and its effects on water resources in Qazvin province. Therefore, the goal of this study was to determine the greenhouse cucumber water requirement and provide a model for estimating evapotranspiration of cucumber under greenhouse condition. Also, determining greenhouse cucumber productivity in Qazvin province and evaluating the effect of this improvement on water resources were other objectives.
Materials and Methods: This research was carried out in a greenhouse near Qazvin city. The height of the greenhouse from the ground was 4 meters, and its plastic cover was made of polyethylene. Experiments were carried out in greenhouse with greenhouse seedling on 20-3-2015 in two rows of pot. The greenhouse was equipped with the necessary tools to measure temperature, maximum and minimum temperature, relative humidity, and solar radiation. Soil texture in this research was clay loam with 30, 32 and 38 percent of sand, silt and clay, respectively. The water content was, , 31% and 16 percent at field capacity (FC) and permanent wiling point (PWP) respectively. An irrigation interval of two days (a favorable condition) was considered. In this experiment, the seeds of the Royal cucumber were used to coincide with the planting time and harvesting length. The plastic pots with a diameter of 18 cm and a height of 23 cm were utilized. The pots were filled with equal quantities of fine and fine gravel (for drainage) and then with the agricultural soil prepared for cucumber cultivation. In order to provide conditions similar to the actual cucumber planting in the flower bed, the pots were placed close to the greenhouse. The irrigation of the plants was carried out manually for 83 days. The relative humidity, temperature and radiation were measured hourly. Further, the effects of irrigation on different characteristics of the test plants were observed and recorded. The moisture content was measured by weight and soil moisture reduction in full irrigation was compensated for the FC moisture content in each irrigation interval. Until 30 days after planting (Stages 4-6), the pots were irrigated with equal amounts. In order to evaluate the effects of deficit irrigation, four treatments were considered. These treatment were as follows: first treatment (FI): irrigation depth equal to 100% of the plant evapotranspiration with five replications, treatment (DI20): irrigation depth equal to 80% of the plant evapotranspiration with five replicates, treatment 3: (DI40) irrigation depth equal to 60% of the plant evapotranspiration with five replicates and the fourth treatment (DI60): irrigation depth equal to 40% of the plant evapotranspiration with five replications.
Results and Discussion: The maximum and minimum evapotranspiration was 8.7 and 1.06 mm/day in 61 and 13 days after transplanting, respectively. By investigation different mathematical models, the best models for estimation of cucumber evapotranspiration in greenhouse was the power model based temperature, humidity and height of crop with R2 of 0.86. The FAO-Penman-Monteith and Blaney-Criddle models exhibited the best and worst performance with R2 of 0.42 and 0.24, respectively. The cucumber water productivities in greenhouses ranged from 9.23 to 22.44 Kilograms per cubic meter. This wide water productivity range shows the importance of management and operation in water productivity improvement in greenhouses.
Conclusion: Estimation of greenhouses cucumber water requirement and water productivity are very important. The best model for estimating cucumber evapotranspiration in greenhouse was the power model based on temperature, humidity and height of crop with R2 of 0.86. In this study, cucumber water productivity was estimated in Qazvin greenhouses. The results showed that cucumber water productivities ranged from 9.23 to 22.44 Kilograms per cubic meter. Consequently, 117 ha greenhouse is required for producing the present value of cucumber in the province. This option would save 15 millions of cubic meter water in this area. Development of greenhouses with regarding to various economic and social aspects can help decision-makers in solving water shortage problems.
Saeid ghavam seeidi noghabi; Abbas Khashei-siuki; Hossein Hammami
Abstract
Introduction: Water is one of the most important factors limiting agricultural developments in arid and semi-arid regions in the world. One of the important issues of water management is assessment and determination of water requirement of plants. One of the main water management strategies in agriculture ...
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Introduction: Water is one of the most important factors limiting agricultural developments in arid and semi-arid regions in the world. One of the important issues of water management is assessment and determination of water requirement of plants. One of the main water management strategies in agriculture is to assess and determine the plants water requirement. Due to dry and semi-arid weather conditions in Iran the optimal use of water resources is crucial. Plants water requirements are the important parts of the hydrological cycle, and its precise estimation is essential for water budget studies, facilities, management, design of new irrigation systems and water resources management. The determination of behavior and characteristics non-reference vegetation compared to reference vegetation (grass) is the first step in estimating the evapotranspiration of crops. It is important to determine the crop factor in order to measure the water requirement of the crop at different stages of growth. The crop coefficient expresses the effects of crop and soil moisture on a non-reference plant species relative to the reference plant. Among the medicinal herbs, Hibiscus sabdariffa L. is an annual tropical and sub-tropical herbaceous plant belongs to Malvaceae family. Red calyces of Roselle are a source of anthocyanins (about 1.5 g/100 g dry weight), vitamin C and other antioxidants, such as flavonoids (gossypetin, hibiscetine, and sadderetine). Roselle is a medicinal plant that cultivated in Iran especially in Sistan and Baluchestan province. Regarding the long history of cultivation, and high consumption in Iran and the world so far, there has not been a scientific report about Roselle water requirement at different stages of growth. Therefore, this research was carried out with the aim of obtaining Roselle water coefficients and studying the pattern of its changes during the growing season in dry and semi-arid climates of Birjand using the lysimetric method.
Materials and Methods: To determine the Roselle crop coefficient, as a valuable medicinal herb, a lysimetric experiment was conducted in faculty of agriculture, Birjand University during the growing season in 2017. The lysimeters used for this experiment have 20 cm diameter and 16 cm in height. Three lysimeters used for sowing Roselle and three lysimeters used for reference plant. There are six orifices as a water drain in the bottom of each lysimeter. Floor of lysimeter covered by 5 cm granule layer, then filled with soil and cow decayed fertilizer mixture. In each lysimeter, 25 seeds of Roselle were sown. To determine potential evapotranspiration, 12 centimeters height grass was used as the reference plant. Water requirement of Roselle was determined by water balance method. The Roselle growth period was divided into four stages included initial (10% plant growth after emergence), development (between 10% plant growth and before flowering), middle (between early flowering and end flowering), and end (between end flowering and seed ripening). Weed control was achieved by hand hoeing during the growth season. Drainage water was measured by weighting and soil moisture hold at field capacity during the growth season.
Results and Discussion: Results of this study showed that Roselle plant in the initial stage due to slow growth and low transpiration have low Kc compared to middle and development stage. The average coefficient of Roselle was 1.26, 1.55, 1.81, and 0.96 in the initial, development, middle, and end stages respectively. Duration of growth stages for Roselle in Birjand region is 35, 75, 100, and 30 days after emergence. This results revealed an increasing trend from initial to development and middle stages. However, in the end stage of Roselle, Kc decreased. The result of this study showed that evapotranspiration of Roselle was 3819.57 mm whereas the reference plant evapotranspiration was 2420.3 mm. Due to water shortage in the arid and semi-arid region, this plant is not proper for sowing in this area.
Conclusions: According to the results of this study, the annual average evapotranspiration rate of the Roselle was 3819.57 mm whereas the reference plant evapotranspiration was 2420.3 mm. Therefore, the water requirement of Roselle is very high during growth period. Finally, according to the high water requirement and water deficient in Birjand, Iran; it seems that Roselle is not a proper plant for sowing in this area.
reza saeidi; abbas Sotoodehnia; Hadi Ramezani Etedali; Bizhan Nazari; Abbas Kaviani
Abstract
Introduction: Estimating the actual evapotranspiration of the crops, is so important for determining the irrigation needs. Typically, the climatic, vegetative and management parameters are effective on actual evapotranspiration. If the crops are exposed to salinity, fertility and other stresses, reduce ...
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Introduction: Estimating the actual evapotranspiration of the crops, is so important for determining the irrigation needs. Typically, the climatic, vegetative and management parameters are effective on actual evapotranspiration. If the crops are exposed to salinity, fertility and other stresses, reduce actual evapotranspiration and yield. The correct estimation of the actual evapotranspiration of crop will allow agricultural planners to the better agricultural water management. Previous researches show water stress and soil nitrogen deficiency (as management stresses), effect on increasing of stomatal resistance and reducing of crops evapotranspiration. Thus, goal of this study was to investigate the effect of salinity and soil nitrogen deficiency on the amount of Ks coefficient and readily available water of maize.
Materials and Methods: This study was conducted in research farm at University of Imam Khomeini International, Qazvin, Iran during June to November 2017. In this research, the effects of saline water and soil nitrogen deficiency on Maize (SC 704) evapotranspiration, were investigated. The applied treatments included irrigation with saline water (in four levels: 0.5 (S_0), 1.2 (S_1), 3.5 (S_2) and 5.7 (S_3) dS/m) and soil fertility (in four levels: nitrogen fertilizer consumption at 100 (N_0), 75 (N_1), 50 (N_2) and 25% (N_3)). The experimental design used in this research was a completely randomized block design with three replications. In this experiment, maize seeds were cultivated in the plots with Length and width of 3×3 meters. The prometer device (Model: AP4) was also used to measure stomatal resistance of maize leaf. Determining the irrigation schedule, was based on the soil moisture reached to the limit of RAW (Readily Available Water). At the same time, with increasing stomatal resistance, RAW was calculated and irrigation was done. Evapotranspiration of the under stress plants were ET_(c-adj) and evapotranspiration of S_0 N_0 treatment was ET_c. The stress factor (K_s ) is calculated by ET_(c-adj)/ET_c. The values of RAW and K_s were analyzed by SPSS software. K_s coefficient was modeled with amounts of salinity stresses and soil nitrogen deficiency.
Results and Discussion: The results of this study showed that the interaction between two factors of salinity stress and nitrogen deficiency on the K_s and RAW parameters (in level: 1%) are significant. K_s coefficient at the levels of S_1, S_2 and S_3, were 0.95, 088 and 0.77, respectively. In saline water of 0.5 (dS/m), the K_s coefficient of N_1, N_2 and N_3 were 0.98, 0.96 and 0.95, respectively. With increasing the 1(dS/m) salinity of water and 25% reduction in nitrogen consumption, decreased the K_s amount about 4.5% and 1.7%, respectively. The reason of results is that with increasing of water salinity, decreases the osmotic potential of water in the soil and the crop needs to consume more energy to obtain water. Thus, amount of crop transpiration is reduced and soil water content is remained. The linear, exponential, logarithmic, polynomial and power functions were fitted between N_i/N_0 and S_i/S_0 data. The ability of the above functions to estimate the K_s coefficient value was evaluated. The polynomial function has a good function for estimating the K_s coefficient. In the S_0، S_1، S_2 and S_3 treatments, by changing the fertility value from N_0 to N_3, amounts of RAW were 63.7, 58.7, 55.4 and 42% , respectively. Also in N_0، N_1، N_2 and N_3 treatments, with changing the salinity of water from S_0 to S_3, RAW values were 51.7, 46.3, 42.7 and 42%, respectively. Therefore, stresses that reduce crop evapotranspiration are effective on reducing the amount of RAW. In this situation, the actual water requirement of the crop is less than the potential evapotranspiration of the area.
Conclusions: Increasing water salinity and nitrogen deficiency decrease evapotranspiration of maize and increase soil water content. By calculating the stress coefficient (K_s ), it is possible to estimate the actual evapotranspiration of maize, in Qazvin. Thus, the amount of irrigation water is adjusted according to the actual water requirement of maize. Under salt stress conditions with increasing the soil nitrogen, Can be increased the K_s coefficient and evapotranspiration of maize. Therefore, calculating the crop's water requirement based on the existence of strtesse, it will help to saving water.
M. J.Fereidooni; H. Farajee
Abstract
Introduction: In Iran, due to reduction of water resources and increasing of water losses in the various methods of the surface irrigation pressurized irrigation methods, especially drip irrigation have got many attentions. Application of the plastic mulch method is used in cultivation of early sweet ...
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Introduction: In Iran, due to reduction of water resources and increasing of water losses in the various methods of the surface irrigation pressurized irrigation methods, especially drip irrigation have got many attentions. Application of the plastic mulch method is used in cultivation of early sweet corn. Application of this technique due to its temperature provides both plant growth and early maturity and then causes the on-time delivery of product to the target market. Additionally, to reduce water consumption, the use of germinated seedlings in the greenhouse and move it under plastic on the farm, productivity will increase. The aim of this study was to evaluate irrigation levels on yield of sweet corn by using plastic mulch, and the feasibility of seedling cultivation to early crop.
Materials and Methods: In order to evaluate the effect of different irrigation levels and cultivation techniques on water use efficiency and quality and quantity yield of sweet corn, an experimental program was carried out as split plot in randomize complete blocks design with three replication in Faculty of Agriculture, Research Field Station of Yasouj University in 2015. The main factor consisted of three levels of irrigation: 100 (I1), 75 (I2) and 50 percentage of water requirement (I3) and the sub-factor was including cultivation techniques of sweet corn in six levels: seed cultivation of sweet corn under plastic mulch on 4 April (CT1), seedling cultivation under plastic mulch on 4 April (CT2), seed cultivation to conventional method of sweet corn on 5 May (CT3), seed cultivation of sweet corn under plastic mulch on 5 May (CT4), seedling cultivation of sweet corn under plastic mulch on 5 May (CT5) and seedling cultivation to conventional method of sweet corn on 5 May (CT6).
In order to establish plastic mulch, after seed and seedling cultivation of sweet corn with installation of irrigation tape tubes, steel bars which were made in a semi-circular shape, were placed on rows and plastics were laid on it. After the establishment of the seedling on the farm, the irrigation levels were applied by volumetric counters. When the plant height was equal to the height of plastic tunnels, it was tried to pierce the plastic to grow suitability. During the time of maturity product, a 2 m2 plot in the middle of farm was selected and the ears were separated and weighed, and the forage yield was weighted. The grains of sweet corn were separated and canned yield was measured. The content of grain sugar, sucrose and fructose were measured by means of HPLC method, and the content of grain nitrogen with using of micro Kjeldahl’s method achieved. Statistical analysis was performed using SAS software. The mean values were compared by using LSD multiple range tests at 5% level. Figures were depicted by using of Excel software.
Results and Discussion: The results indicated that irrigation interaction and cultivation techniques were significant on ear yield, the canned yield, water use efficiency, and forage yield. The maximum ear yield obtained in treatments of I2CT1, I1CT1, I2CT2 and I1CT2 were equal to 14420, 14414.4, 13691.7 and 13513.5 kg ha-1, respectively and the maximum water consumption content for mentioned treatments were equal to 2521, 3362, 2385 and 3180 m3 ha-1, respectively. The minimum ear yield obtained in treatment of I3CT3 was equal to 706 gm-2. Water stress delayed the physiological processes including silk rating and tassel emergence, so that, it reduced growth and plant height and finally leaded to the reduction of grain yield. The maximum canned yield were obtained in treatment of I1CT1, I2CT1, I1CT2 and I2CT2 equal to 558.7, 551.1, 536.2 and 527.4 gm-2, respectively. Higher grain yield of sweet corn under plastic mulch in comparison with non plastic mulch, was due to increasing of dry matter accumulation before the silk production. It seems that increasing temperature and water content under plastic mulch resulted in an increase in grain dry matter accumulation. The maximum water use efficiencyfresh grain was obtained in treatment of I2CT2, I2CT1, I3CT2 and I3CT1 equal to 2.21, 2.18, 2.16 and 2.14 kgm-3, respectively. With increasing of water consumption water use efficiencyfresh grain decreased. Maximum forage yield was obtained in I1CT1 equal 2008 gm-2 and minimum forage yield was obtained in I3CT6 equal 1237 gm-2. Available water under plastic mulch, increased plant growth by increasing of leaf area index and shoot biomass due to stomata opening.
The effect of irrigation were significant on grain sucrose percentage, and content of protein. Moreover cultivation techniques effect was also significant on content of grain sugar, sucrose percentage and subsequently the content of grain protein. The maximum grain sucrose percentage was for treatment of 100% water requirement of sweet corn which was equal to 4.92%. Treatment of 75 percentage water requirement, also, the minimum grain sucrose percentage equal to 4.11% was obtained in treatment of 50 percentage water requirement. Retaining of moisture increased the amount of sugar and grain sucrose content. The maximum content of grain protein was equal to 11.41% in treatment of 100 percentage water requirements; also the minimum content of grain protein equal 8.58% was obtained in treatment of 50 percentage water requirement.
By reducing soil moisture, the content of protein and sugar grain increased, so the maximum content of grain protein and sugar were obtained in treatment of 50 percentage water requirement, although the maximum levels of irrigation reduced the content of protein and sugar. Under stress conditions, the plant material requirement is not enough, so by reducing nutrient transport, the leaf and stem cell development delayed, resulting in reduced plant height, leaf area, the content of grain protein, sugar. Finally, dry matter accumulation in the grain decreases with the transfer of nutrients from the leaves, and then it caused early death the leaf.
Conclusions: Application of seedling and plastic mulch accelerated plant growth, its development and then it was out of season production. If there are not water restrictions, application of treatment of 100 percentage water requirement of sweet corn with plastic mulch is desirable to maximum yield produce. Average of water consumption was in treatments of plastic mulch and non-plastic mulch equal to 2735 and 3411 m3 respectively. Maximum content of grain protein and sucrose percentage were obtained in treatments contains plastic mulch. Seedling cultivation in comparison with seed cultivation showed minimum content of grain sugar and grain sucrose percentage. In order to achieve the maximum quality and quantity yield in areas that are faced to water restriction, it is possible to use treatment of 75 percentage of water requirement and seeding cultivation under plastic mulch.
leila jalali; J. Bazrafshan; A.R. Tavakoli
Abstract
Introduction: There have been several indices for agricultural drought monitoring such as Palmer Drought Severity Index (PDSI), Crop Moisture Index (CMI) and Reconnaissance Drought Index (RDI). These indices model the general conditions of soil moisture as a function of climatic parameters such as temperature ...
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Introduction: There have been several indices for agricultural drought monitoring such as Palmer Drought Severity Index (PDSI), Crop Moisture Index (CMI) and Reconnaissance Drought Index (RDI). These indices model the general conditions of soil moisture as a function of climatic parameters such as temperature and rainfall and they are not appropriate to any specific crop. Crop- Specific Drought Index (CSDI) is among few indices which directly take into account evapotranspiration for drought monitoring. This index is defined based on the ratio of actual evapotranspiration (ETa) to potential evapotranspiration (ETp). Literature review of agricultural drought monitoring in Iran reveals that was mainly used Reconnaissance Drought Index (RDI) and in some cases Drought Severity Index Palmer (PDSI) which have less associated with the growth or performance of the specific crop or not. In this paper, a Crop Specific Drought Index (CSDI) model was evaluated for rain-fed wheat in a cold-temperate climate. Then, it’s correlation with RDI was assessed.
Materials and Methods: In this study, using 9 years of data of meteorology, soil, and crop yield and phenology, a CSDI model has been calibrated and validated for rain-fed wheat. A two-layer model of daily soil water balance was used to CSDI calculation. The first layer is the current root growth zone which its depth increases with time. The second layer is between the first layer and maximum depth of root growth which its depth decreases by root growth and the thickness of this layer becomes zero when the root growth is Maximum. Actual daily Evapotranspiration (ETa) was calculated based on two-layer model of daily soil water balance. For this, we used the moisture content of the first layer (active), potential evapotranspiration and daily rainfall values. The statistical indices of error analysis like RMSE, MAE and Index of Agreement was used for assessment of CSDI model. Then, to investigate the correlation possibility of crop specific drought severity, Reconnaissance Drought Index (RDI) was used which is based on two variables of potential evapotranspiration and precipitation. In fact, RDI considers the precipitation as a factor of moisture input and the potential evapotranspiration as a factor of moisture exhaust.
Results Discussion: At Kermanshah station high coefficient of determination (0.95), relatively high index of agreement (0.747), and low error values (RMSE =0. 098 and MAE =0. 068) was obtained. Sensitivity coefficients during vegetative and productivity stages were obtained 1.31 and -0.0542, respectively. As a result, crop yield at vegetative stage severely affected by aridity stress while at productivity stage there was no sensitivity. In fact, water demand supply is vital at vegetative stage .Range of RDI at Kermanshah station was between 1.13 to -2.59. This threshold is the condition between "moderately wet" and "extreme drought". Correlation between the two index was started from March (R2 =0. 467) and persisted to September (R2 =0. 717). But the highest coefficients of determination were related to July to august (0. 738). Although CSDI didn’t affect by drought stress during October to February, it affected by moisture of March onward. RDI incorporating precipitation and potential evapotranspiration is one of the most recent developments for the assessment of drought severity through drought indices. That is why this index is chosen to investigate the relationship with CSDI. Actually, both indices get evapotranspiration factor in the agricultural drought monitoring. Based on the results, there is a good correlation between two indices. Since the CSDI is relay on ETa to ETp ratio and RDI is based on the P/ ETp ratio, it can be concluded that there is a possible to replacement of ETa with rainfall (R) in the CSDI equation.
Conclusion: Many indices and indicators are available to assist in the quantitative assessment of drought severity, and these should be evaluated carefully for their application to each region or location and sector. This paper presents a CSDI model which compared with RDI. Based on the results of this analysis, CSDI model was performed well in high values of coefficients of determination and Index of Agreement, and low values of errors. Therefore, the CSDI seems to be a reliable index to assess agricultural drought. Furthermore, it is observed a reliable relation between CSDI and RDI during crop growth period. Due to good correlation of CSDI and RDI, it can be proposed to replacement of rainfall (R) instead of ETp in the CSDI equation.
Farzin Parchami-Araghi; seyed majid mirlatifi; Shoja Ghorbani Dashtaki; Majid Vazifehdoust; Adnan Sadeghi-Lari
Abstract
Introduction: In order to provide more realistic representation of processes governing the water and energy balances as well as water quality and plant physiological processes, weather data are needed at finer timescales than currently are available at most regions. In this study, a physically based ...
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Introduction: In order to provide more realistic representation of processes governing the water and energy balances as well as water quality and plant physiological processes, weather data are needed at finer timescales than currently are available at most regions. In this study, a physically based framework was developed to disaggregate daily weather data needed for estimation of subdaily reference evapotranspiration, including air temperature, wind speed, dew point, actual vapour pressure, relative humidity, and solar radiation. In this paper, the results of performance comparison of the utilized disaggregation approaches are presented.
Materials and Methods: In developed framework, missing daily weather data are filled by implementation of a search-optimization algorithm. Meanwhile, disaggregation models can be calibrated using Unified Particle Swarm Optimization (UPSO) algorithm. Daily and subdaily solar radiation is estimated, using a general physically based model proposed by Yang et al. (YNG model). Long-term daily and three-hourly weather data obtained from Abadan (59 years) and Ahvaz (50 years) synoptic weather stations were used to evaluate the performance of the developed framework. In order to evaluate the accuracy of the different disaggregation models, the mean error (ME), mean absolute error (MAE), root mean square error (RMSE), and Pearson correlation coefficient (r), and model efficiency coefficient (EF) statistics were calculated. Different contributions to the overall mean square error was decomposed, using a regression-based method.
Results and Discussion: The results indicated that compared to the WAVE I, WAVE II, WCALC, ERBS, and ESRA models, the calibrated TM model had the best performance to disaggregate daily air temperature with a EF of 0.9775 to 0.9924. Compared to air temperature disaggregation models with an arbitrary value for the time of maximum and minimum air temperature, the models in which the above mentioned times are described as a function of sunrise and/or sunset had better performance in describing the diurnal variations of the air temperature. HUM III model (based on cosinusoidal disaggregation of daily actual vapour pressure) had the best performance to disaggregate daily dew point, actual vapour pressure, and relative humidity with an EF of 0.7266 to 0.8896. In addition, subdaily wind speeds were predicted with an EF of 0.3357 to 0.6300. The results showed high agreement between daily and sum-of-subdaily solar radiation (with an EF of 0.9801 to 0.9729). The use of the WAVE II and HUM II (based on linear disaggregation of relative humidity) models can be recommended for the regions with no subdaily weather data needed for calibration of the weather data disaggregation models. The results indicate the need for calibration of Green and Kozek model for disaggregation of the daily wind speed at different regions.
N. Reyhani; Abbas Khashei siuki
Abstract
Introduction: Water is one of the most important factors limiting agricultural developments in arid and semiarid regions in the world. To avoid and exit from water crisis, a proper agricultural and water resource management is required. One of the important parameters in this regard, is determination ...
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Introduction: Water is one of the most important factors limiting agricultural developments in arid and semiarid regions in the world. To avoid and exit from water crisis, a proper agricultural and water resource management is required. One of the important parameters in this regard, is determination of crops’ evapotranspiration. Evapotranspiration, water evaporation from the soil surface and transpiration of vegetation cover have a major trend and a key element in hydrological cycle for management of water resources, particularly in arid and semi-arid. Evapotranspiration is function of the soil, climate, land use, aerodynamic resistance levels and topography of the area. To provide a suitable irrigation schedule and apply an optimal water use management, determination of water requirement and crop coefficients in various growth stages seems necessary. Crop coefficient can be found through dividing the actual evapotranspiration by the potential evapotranspiration. Since the cuminum is commonly used in Birjand and has cultivated in farm and crop coefficients has not been determined , this study aimed to determine the crop coefficients of cuminum using lysimeter water balance in arid and semi-arid climatic conditions.
Materials and Methods: In this research, in order to determine cuminum crop coefficients, that is one of the important herbs, a lysimetric experiment was conducted during growth season in faculty of agriculture, Birjand university. This project, was done in lysimeter. For this purpose and due to the size and plant height in three lysimeter (as replications) with a diameter of 20 and a height of 16 cm was used order to the cultivation of Cuminum. In order to drainage at the bottom of each lysimeter was built orifice. For easily of lysimeters drainage, lysimeter floor was poured by small and large sand and lysimeter was filled by soil and animal Fertilizers for better plant growth. Three lysimeters were used; and water requirement of cuminum was calculated using water balance method. To calculate potential evapotranspiration, grass with 12 centimeters height was used as the reference plant. Crop coefficient can be achieved by dividing the actual evapotranspiration to reference evapotranspiration and is not fixed growth period. The cumin plant growth period was divided four stages (initial, development, middle and end). The initial phase of up to 10% on seed germination and plant growth, from 10 percent to flowering development stage, middle stage and final stage of the start of flowering to product reaches to harvest is the end of the middle stage. In each lysimeter average number of 20-15 of seed to increasing germination, were planted on the February 9, 2012. To control weeds, weed was done handing during the growing season. Drainage water is controlled over a period of time measured with weighting method and deep and volume of water was measured. Soil moisture at field capacity using pressure plates was measured. Measuring soil water content and determine irrigation time.
Results and Discussion According to the results obtained for the crop coefficient can be concluded that in the initial stages of plant growth that plant size is small, transpiration is low and therefore Kc have low value. In the middle and development stage increases canopy and increased transpiration rate and increases Kc. At the end stage to reducing activity of the leaves (old leaves) reduced transpiration. The average crop coefficient of cumin in the initial phase of growth during the study to 0.65, then with increasing plant growth, leaf area index were increased and crop coefficient increased to 0.92 in development stage. In the middle of this amount is 1.21 and in the end the 0.85 reached. Average crop coefficients for a four-stage is 0.9. Duration of growth stages for cuminum crops in Birjand region is 24 days for initial stage, 40 days for middle stage and 31 days for development and 19 days for end stage of growth stages.
Conclusions In this study according to important of drug and economic for cuminum plant and that there isn’t report for crop coefficient cuminum and Birjand region, we cultivate cuminum in arid area of Birjand in 2011 year. The results of lysimeters showed that Duration of plant growth stages and value of crop coefficients in the initial , development, middle and end stages, respectively (24, 40, 31 and 19 days) and (0.65, 0.921.21 and 0.85) respectiely.
Farzin Parchami-Araghi; seyed majid mirlatifi; Shoja Ghorbani Dashtaki; Adnan Sadeghi-Lari
Abstract
Introduction: Subdaily estimates of reference evapotranspiration (ETo) are needed in many applications such as dynamic agro-hydrological modeling. The ASCE and FAO56 Penman–Monteith models (ASCE-PM and FAO56-PM, respectively) has received favorable acceptance and application over much of the world, ...
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Introduction: Subdaily estimates of reference evapotranspiration (ETo) are needed in many applications such as dynamic agro-hydrological modeling. The ASCE and FAO56 Penman–Monteith models (ASCE-PM and FAO56-PM, respectively) has received favorable acceptance and application over much of the world, including the United States, for establishing a reference evapotranspiration (ETo) index as a function of weather parameters. In the past several years various studies have evaluated ASCE-PM and FAO56-PM models for calculating the commonest hourly or 15-min ETo either by comparing them with lysimetric measurements or by comparison with one another (2, 3, 5, 9, 10, 11, 16, 17, 19). In this study, sub-daily ET o estimates made by the ASCE-PM and FAO56-PM models at different timescales (1-360 min) were compared through conduction of a computational experiment, using a daily to sub-daily disaggregation framework developed by Parchami-Araghi et al. (14).
Materials and Methods: Daily and sub-daily weather data at different timescales (1-360 min) were generated via a daily-to-sub-daily weather data disaggregation framework developed by Parchami-Araghi et al. (14), using long-term (59 years) daily weather data obtained from Abadan synoptic weather station. Daily/sub-daily net long wave radiation (Rnl) was estimated through 6 different approaches, including using two different criteria for identifying the daytime/nighttime periods : 1) the standard criteria implemented in both ASCE-PM and FAO56-PM models and 2) criterion of actual time of sunset and sunrise in combination with 1) estimation of clear-sky radiation (Rso) based on the standard approach implemented in both ASCE-PM and FAO56-PM models (1st and 2nd Rnl estimation approaches, respectively), 2) integral of the Rso estimates derived via a physically based solar radiation model developed by Yang et al. (25), YNG model, for one-second time-steps (3rd and 4th Rnl estimation approaches, respectively), and 3) integral of the calculated Rnl based on Rso estimates derived via YNG model for one-second time-steps (5th and 6th Rnl estimation approaches, respectively). The capability of the two models for retrieving the daily ETo was evaluated, using root mean square error RMSE (mm), the mean error ME (mm), the mean absolute error ME (mm), Pearson correlation coefficient r (-), and Nash–Sutcliffe model efficiency coefficient EF (-). Different contributions to the overall error were decomposed using a regression-based method (7).
Results and Discussion: Results showed that during the summer days, 24h sum of sub-daily radiation and aerodynamic components of ETo and the estimated ETo derived from both models were in a better agreement with the respective daily values. The reason for this result can be attributed to the nighttime value of cloudiness function (f) and the longer nighttime during the cold seasons. Because the nighttime values for f are equal the f value at the end of the previous daylight period until the next daylight period. The difference between sub-daily ETo derived from the ASCE-PM and FAO56-PM models during the day and night was highly dependent on the wind speed. In case of both models, daily aerodynamic component of ETo (ETod,aero) were reproduced more efficiently, compared to radiation component (ETod,rad). Except in the case of 6th Rnl estimation approach, FAO56-PM model (with a mean model efficiency (MEF) of 0.9934 to 0.9972) had better performance in reproducing the daily values of ETo (ETod), compared to ASCE-PM model (with a MEF of 0.9910 to 0.9970). The agreement between 24h sum and daily values of aerodynamic component had a lower sensitivity to the adopted time-scale, compared to the radiation component. Compared to the FAO56-PM model the performance of the ASCE-PM model in reproducing the ETod,rad, ETod,aero and ETod had higher sensitivity to the approach utilized for calculation of Rnl and hence, to the uncertainty of net radiation. Results showed that a smaller time step does not necessarily leads to an improvement in agreement between 24h sum of subdaily and daily values of ETo. Deficiency of the standard daytime/nighttime identification criteria resulted in a higher daily averaged daytime (1.3831 to 1.6753 h) used in cloudiness function calculations, compared to the respective value used in calculations of the radiation and aerodynamic components. In order to estimate the sub-daily ETo under climatic condition of the studied region, the use of ASCE-PM model based on the 6th Rnl estimation approach, (ASCE-PM)6, with a MEF of 0.9970 is preferred, compared to other studied alternatives. Another advantage of the (ASCE-PM)6 and (FAO56-PM)6 models is their computational efficiency in case of their implementation in hydrological models.
H. Emami Heidari; H. Jafari; Gh. Karami
Abstract
Management of agricultural practices plays a vital role in reducing the use of limited water resources in arid and semi-arid regions which could result in their sustainability. In this research, the role of managing agriculture in sustaining flow of Zayandeh-rud was studied by calculation of rice water ...
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Management of agricultural practices plays a vital role in reducing the use of limited water resources in arid and semi-arid regions which could result in their sustainability. In this research, the role of managing agriculture in sustaining flow of Zayandeh-rud was studied by calculation of rice water requirement (actual evapotranspiration) in paddy fields of Zarrin-shahr by using method of FAO-56 and comparing the results assuming a shift in cropping pattern from rice to other crops. Rice water requirement was estimated at 1485 mm and the volume of water required for irrigation of paddy fields with area of about 6630 Hectare was estimated at 77 MCM. Volume of irrigated waterwas also evaluated by water balance method, confirmed the reliability of FAO-56 method. The results show that, replacing rice or wheat-rice cropping pattern with some possible crops such as bean, maize, walnut, apple and grape decreases irrigation requirements about 27, 15, 24, 29 and 40 MCM, respectively. Generalizing results for the total paddy fields in Isfahan Province with estimated area of about 20000 Hectare will result in an increase of about 3.4 to 9.1 m3/s in Zayandeh-rud discharge during critical months of June to October, when the river flow highly decreases, causing sustainable flow of the river through the year.
vahid Rezaverdinejad; M. Hemmati; H. Ahmadi; A. Shahidi; B. Ababaei
Abstract
In this study, the FAO agro-hydrological model was investigated and evaluated to predict of yield production, soil water and solute balance by winter wheat field data under water and salt stresses. For this purpose, a field experimental was conducted with three salinity levels of irrigation water include: ...
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In this study, the FAO agro-hydrological model was investigated and evaluated to predict of yield production, soil water and solute balance by winter wheat field data under water and salt stresses. For this purpose, a field experimental was conducted with three salinity levels of irrigation water include: S1, S2 and S3 corresponding to 1.4, 4.5 and 9.6 dS/m, respectively, and four irrigation depth levels include: I1, I2, I3 and I4 corresponding to 50, 75, 100 and 125% of crop water requirement, respectively, for two varieties of winter wheat: Roshan and Ghods, with three replications in an experimental farm of Birjand University for 1384-85 period. Based on results, the mean relative error of the model in yield prediction for Roshan and Ghods were obtained 9.2 and 26.1%, respectively. The maximum error of yield prediction in both of the Roshan and Ghods varieties, were obtained for S1I1, S2I1 and S3I1 treatments. The relative error of Roshan yield prediction for S1I1, S2I1 and S3I1 were calculated 20.0, 28.1 and 26.6%, respectively and for Ghods variety were calculated 61, 94.5 and 99.9%, respectively, that indicated a significant over estimate error under higher water stress. The mean relative error of model for all treatments, in prediction of soil water depletion and electrical conductivity of soil saturation extract, were calculated 7.1 and 5.8%, respectively, that indicated proper accuracy of model in prediction of soil water content and soil salinity.
Hamid Mirhashemi
Abstract
In this study, in order to analyze the changes trend of the crop water requirement as the aspect of climate change in East Azerbaijan, we have adopted FAO Penman- Monteith reference crop evapotranspiration and 15 variables associated with it. By using nonparametric methods of Spearman, Man- Kendall ...
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In this study, in order to analyze the changes trend of the crop water requirement as the aspect of climate change in East Azerbaijan, we have adopted FAO Penman- Monteith reference crop evapotranspiration and 15 variables associated with it. By using nonparametric methods of Spearman, Man- Kendall and Sen’s Estimator in twelve monthly and annual series for each station, the trends have been explored. The results of these two test statistics indicate that the significance of the respective phenomenon is being studied in two separate clusters. The first cluster consists of Tabriz and Maragheh stations the entire time series, the time series exceptions of April in Tabriz, the rest of the series with the significant increase in confidence levels are 95% and 99%. The second cluster consists of Ahar, Sarab, Mianeh and Julfa stations that mentioned phenomenon of jointly in the time series in March with a significant increase in the same levels of trust. Also the test results from other variables show that despite a series of meteorological variables, no significant trends were, but due to the influence of the reference crop evapotranspiration and the significant impact it has on the superposition. Finally, we should acknowledge that the study of climate change in the region, is not just dependent on the climate variables and could be caused by other variables too.
abolfazl Mosaedi
Abstract
Prediction of precise forage production and proper management strategies requires identifying key climatic factors in different regions. The objective of this research is to compare forage production in different region based on climatic factors and drought indices. The study sites include Arak, Roudshore, ...
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Prediction of precise forage production and proper management strategies requires identifying key climatic factors in different regions. The objective of this research is to compare forage production in different region based on climatic factors and drought indices. The study sites include Arak, Roudshore, Baghic, and Gharahso in Central and Qom provinces. Climatic factors and drought indices include precipitation, temperature, evapotranspiration, standardized precipitation index (SPI), and Reconnaissance Drought Index (RDI). For each climatic variable/or indices, 33 time periods of 1, 2, 3, 4, 6, and 9-month were specified. We have used Principle Component Analysis to decline the number of variables and then, the appropriate time periods were selected. By using stepwise and best subset, the relationship between forage production and each of the climate factors and indices was modeled. To select model, assessment statistics of R, MBE, RMSE, MARE, and IPE were used. Finally, to predict forage production in Roudshore, Baghic, and Gharahso sites, models based on evapotranspiration (RMSE=7.7, r=0.99), RDI (RMSE=3.1, r=0.99) and precipitation (RMSE=4.0, r=0.99) were selected respectively. The best model was based on the combinations of climatic factors and drought indices (RMSE=0.2, r=0.99) for Arak. In general, the relation between forage production and drought condition based on RDI is stronger than its relationship with precipitation and temperature. As we have used precipitation and evapotranspiration simultaneously in RDI, so this index is more precise than SPI.
H. Ghamarnia; F. Mousabeygi
Abstract
For optimal use of water resources determination of crop coefficients and water requirement for each region is necessary.The present study was conducted to determine the values of water requirement and crop coefficients of Peppermint (Mentha piperita L.) in a semi arid climate. For this purpose, eight ...
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For optimal use of water resources determination of crop coefficients and water requirement for each region is necessary.The present study was conducted to determine the values of water requirement and crop coefficients of Peppermint (Mentha piperita L.) in a semi arid climate. For this purpose, eight water balance drainable lysimeters were used. For those reasons two lysimeters was used for grass and bare soil evapotranspiration estimation. Also in six other lysimeters, peppermint in two groups A (Plant growth was continued until the end of flowering.) and B (plant harvested three times, after reaching a height of 10-12 cm) was planted. Finally the average water requirement of Peppermint in two lysimeters groups A and B were determined as 664.4 and 566.4 mm respectively. Single and base crop coefficients for lysimeters in group A, for the initial, development and middle stages of peppermint growth were determined as, 0.69 ، 1.03 ، 1.27 and 0.29، 0.86، 1.17 respectively . Also the average of single crop coefficients on first, second and third harvests for lysimeters in group B was determined as 0.84 ، 0.92 ، 0.96 respectively.
B. Hassanpour; F. Mirzaei; S. Arshad; H. Kossari
Abstract
In the present study, two methods of predicting evapotranspiration by the use of satellite images were compared. Field data in a corn site was measured at agricultural engineering research institute private farm in 6 days. Consequently MODIS images were used for predicting evapotranspiration by SEBAL ...
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In the present study, two methods of predicting evapotranspiration by the use of satellite images were compared. Field data in a corn site was measured at agricultural engineering research institute private farm in 6 days. Consequently MODIS images were used for predicting evapotranspiration by SEBAL and S-SEBI algorithms. These algorithms are different in predicting sensible heat flux. The results show that RSME value for the net radiation and soil heat flux was respectively 46 and 43 (w/m2). SEBAL algorithm is capable to estimate sensible heat flux more accurate than S-SEBI so it is able to estimate latent heat flux more accurate. The RSME amount in sensible heat flux and latent heat flux for SEBAL algorithm are 58 and 31 (w/m2) respectively. These amounts in S-SEBI algorithm are 111 and 74 (w/m2). The differences between two algorithms could be because of the use of meteorological data in predicting sensible heat flux and aerodynamic resistance in SEBAL algorithm. Also the results show that SEBAL algorithm estimates hourly evapotranspiration by the difference of 0.05 mm/hour which is about 1% of hourly evapotranspiration Whereas S-SEBI predicted it by the difference of 0.11 and 11%. The difference between measured daily evapotranspiration and SEBAL -based daily evapotranspiration was 0.4 mm that is about 1% less than measured. Whereas these differences by S_SEBI are 1mm and 12%.
M. Ghaemi Baygi; mahmood raeini; M. Mousavi Baygi
Abstract
Evapotranspiration is one of the important elements of the hydrologic cycle in agricultural projects. Energy balance (the bowen ratio) is a method for estimating evapotranspiration of plant which is based on measurements of temperature and humidity gradients in two different heights of a plant. An experiment ...
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Evapotranspiration is one of the important elements of the hydrologic cycle in agricultural projects. Energy balance (the bowen ratio) is a method for estimating evapotranspiration of plant which is based on measurements of temperature and humidity gradients in two different heights of a plant. An experiment was conducted in agriculture faculty of Ferdowsi university of Mashhad by using three Lysimeter to estimate evapotranspiration of Gascogne wheat and the resulting were compared with direct method. Required data for measuring the amount of evapotranspiration using energy balance method was obtained throughout plant phenology with one hour intervals using energy balance (model 5200 – DIK) estimation device of evapotranspiration was daily calculated. The rate of daily evapotranspiration that obtained by using energy balance method amounted to 2.4 mm which is in a high correlation (0.98) with the Laysimeter result that was 2.4 mm. The range of Bowen ratio changes was between -1.5 to 1.9 during the day which the negative values occurs after sunset that is the sensible heat flux begins to decrease. The value of Boven ratio gradually increase so that it's maximum value between 8 AM to 9 AM, and then followed a decreasing trend until the afternoon.
