Irrigation
F. Borzoo; H. Ramezani Etedali; A. Kaviani
Abstract
IntroductionClimate change is one of the most important issues in the world in the 21st century which affects various sectors of agriculture, forestry, water and financial markets, and has serious economic consequences (Reidsma et al., 2009). In recent years, the management of agricultural water consumption ...
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IntroductionClimate change is one of the most important issues in the world in the 21st century which affects various sectors of agriculture, forestry, water and financial markets, and has serious economic consequences (Reidsma et al., 2009). In recent years, the management of agricultural water consumption has always been considered as one of the important issues in water resources management. Koochaki and colleagues (Koochaki and Kamali, 2006) by evaluating the climatic indicators of Iran's agriculture showed that during the next 20 years, the average monthly temperature will increase in almost all regions of the country, and the increase in evaporation and transpiration is one of the most important consequences of this warming. Simulated climate parameters can be obtained through different general GCM atmospheric models. Due to the low spatial resolution of these models, its output should be downscaled using dynamic or statistical methods. Materials and MethodsThe LARS-WG model predicts meteorological variables for a period of time in the future by using a series of basic and fine-scale meteorological data, output of one of the GCM models. Research has shown that the LARS-WG model has the necessary accuracy for this task. Calculating the amount of evapotranspiration and yield of very complex plants are time-consuming and dependent on spending a lot of money and limited to the tests performed, the shortness of the test time and also the limitation in the number of scenarios that are checked by the test. Therefore, plant models are considered and evaluated by researchers. The AquaCrop model has demonstrated commendable accuracy in various regions of Iran and globally for forecasting plant growth, water consumption efficiency, and evapotranspiration requirements. These predictions hold significant potential for optimizing irrigation strategies across different agricultural settings. AquaCrop is one of the applied agricultural models that was obtained from the modification and revision of FAO publication No. 33 by prominent experts from all over the world. In this study, the values of green water footprint of winter wheat plant (Pishgam) were estimated in climatic conditions obtained from LARS-WG model and DKRZ database under scenarios 4.5 and 8.5 and at different planting dates (15 October, 1 November, 15 November, 30 November and 15 December), in the next 4 periods (2021-2040, 2041-2060, 2061-2080 and 2081-2100) and by Aquacrop model. Results and DiscussionThe results showed that if planting date is on October 15, in the climatic conditions obtained from the LARS-WG model and under scenarios 4.5 and 8.5, in all future periods, the footprint of green water will increase compared to its value in the base period, and if planting is the rest of the dates, in each of the next 4 periods, the average green water footprint will decrease compared to its value in the base period. The results obtained for the DKRZ database show that the green water footprint attained for the dates of cultivation and periods investigated in scenarios 4.5 and 8.5 does not have a particular trend. On the planting dates of October 15 and November 1 for the periods of 2061-2080 and 2081-2100, the green water footprint will decrease and on the other three dates (15 November, 30 November, and 1 November) for these periods, there will be an increasing trend. On 15 December, for the DKRZ database, in both scenarios defined for all periods, an increase in green water footprint compared to the base period is reported. However, in the period of 2081-2100 in scenario 8.5, a decrease compared to the base period will be observed. The highest amount of green water footprint in all these periods and models for the period 2041-2060 under the climatic conditions of the DKRZ database in scenario 4.5, if the planting date is 15 October, it is estimated that the amount of water consumed is equal to 4272 cubic meters per ton with a standard deviation of 5018 cubic meters per ton is predicted. The lowest footprint of green water for the period 2081-2100 under the climatic conditions obtained from the LARS-WG model in scenario 8.5, if the planting date is on 15 December, is reported to be 232 tons per hectare with a standard deviation of 52.3 tons per hectare.
Irrigation
H. Ramezani Etedali; F. Safari
Abstract
IntroductionEvaluation of plant models in agriculture has been done by many researchers. The purpose of this work is to determine the appropriate plant model for planning and predicting the response of crops in different regions. This action is made it possible to study the effect of various factors ...
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IntroductionEvaluation of plant models in agriculture has been done by many researchers. The purpose of this work is to determine the appropriate plant model for planning and predicting the response of crops in different regions. This action is made it possible to study the effect of various factors on the performance and efficiency of plant water consumption by spending less time and money. Since the most important agricultural product in Iran is wheat, so proper management of wheat fields has an important role in food security and sustainable agriculture in the country. The main source of food for the people in Iran is wheat and its products, and any action to increase the yield of wheat is necessary due to limited water and soil resources. Evapotranspiration is a complex and non-linear process and depends on various climatic factors such as temperature, humidity, wind speed, radiation, type and stage of plant growth. Therefore, in the present study, by using daily meteorological data of Urmia, Rasht, Qazvin, Mashhad and Yazd stations, the average daily evapotranspiration values based on the results of the FAO-Penman-Monteith method are modeled and the accuracy of the two methods temperature method (Hargreaves-Samani and Blaney-Criddle) and three radiation methods (Priestley-Taylor, Turc and Makkink) were compared with FAO-56 for wheat.Materials and MethodsThe present study was conducted to evaluate the accuracy and efficiency of the AquaCrop model in simulation of evapotranspiration and biomass, using different methods for estimation reference evapotranspiration in five stations (Urmia, Qazvin, Rasht, Yazd and Mashhad). Four different climates (arid, semi-arid, humid and semi-humid) were considered in Iran for wheat production. The equations used to estimate the reference evapotranspiration in this study are: Hargreaves-Samani (H.S), Blaney-Criddle (B.C), Priestley-Taylor (P.T), Turc (T) and Makkink (Mak). Then, the results were compared with the data of the mentioned stations for wheat by error statistical criteria including: explanation coefficient (R2), normal root mean square error (NRMSE) and Nash-Sutcliffe index (N.S).Results and DiscussionThe value of the explanation coefficient (R2) of simulation ET and biomass in the Blaney-Criddle method is close to one, which shows a good correlation between the data. The NRMSE and Nash-Sutcliffe values for both parameters and the five stations are in the range of 0-20 and close to one, respectively, which indicates the AquaCrop model's ability to simulate ET and biomass. On the other hand, the value of R2 in the Hargreaves-Samani method for biomass close to one, NRMSE in the range of 0-10 and Nash-Sutcliffe index is more than 0.5, which indicates a good simulation. The NRMSE index in the evaluation of ET and biomass wheat is excellent for the Blaney-Criddle method and about Hargreaves-Samani for ET is poor and for the biomass is excellent.The Turc method with NRMSE in the range of 0-30, explanation coefficient close to or equal to one and a Nash-Sutcliffe index of one or close to one can be used to simulate ET and biomass at all five stations. Also, for biomass simulation, Priestley-Taylor and Makkink methods have acceptable statistical values in all five stations.Based on the value of explanation coefficient (R2) of estimation ET and biomass wheat for radiation methods, the correlation between the data in all three radiation methods is high. Percentage of NRMSE index of Makkink method for wheat in ET evaluation in Qazvin station is poor category and in Urmia and Rasht is good and in Mashhad and Yazd is moderate and about biomass in all five stations (Qazvin, Rasht, Mashhad, Urmia and Yazd) is excellent category, the error percentage of Priestley-Taylor method for wheat in ET evaluation in Yazd station is good and the rest of the stations is poor, about biomass is excellent in all five stations (Qazvin, Rasht, Mashhad, Urmia and Yazd). The error rate of Turc method for wheat in ET evaluation in Urmia, Rasht and Mashhad stations is good and in Qazvin and Yazd is poor and about biomass is excellent in all five stations (Qazvin, Rasht, Mashhad, Urmia and Yazd).ConclusionAccording to the results obtained using Blaney-Criddle method with R2 value close to one, NRMSE in the range of 0-20% (excellent to good) and Nash-Sutcliffe index close to one and Turc method with R2 value close to one, NRMSE in the range of 0-10% (excellent) and Nash-Sutcliffe index close to one was showed a good accuracy of AquaCrop model in simulation of evapotranspiration and biomass with these methods of estimation of evapotranspiration compared to other methods.
Irrigation
F. Zargar Yaghoubi; M. Sarai Tabrizi; A. Mohammadi Torkashavnd; M. Esfandiari; H. Ramezani Etedali
Abstract
IntroductionThe rise in water demand and reduction of water quality and soil in irrigating areas, especially in dry and semi-arid areas of the world, have turned into one of the most crucial challenges for water and soil engineering in recent years. This issue leads us toward optimal quantitative and ...
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IntroductionThe rise in water demand and reduction of water quality and soil in irrigating areas, especially in dry and semi-arid areas of the world, have turned into one of the most crucial challenges for water and soil engineering in recent years. This issue leads us toward optimal quantitative and qualitative management of these valuable resources aimed at achieving economic performance and water productivity. The periodic evaporation and transpiration of the plant in the conditions of simultaneous water and salinity stress are known as one of the most important factors in the qualitative and quantitative growth of the plant yield. Applying mathematical models that simulate the relationship between field variables and yield can be seen as a useful tool in water and soil management issues in such a situation, which has the potential to ensure optimal use of the water and soil resources of any country by providing the plant's water needs and preventing its further loss.Materials and MethodsA factorial experiment was performed in 2019 based on completely randomized blocks design with three replications in plots with an area of 9 square meters at the agricultural and animal husbandry farm of Aliabad Fashafuyeh, located in Qom province to examine the simultaneous effect of different levels of water stress and salinity on the periodic evaporation-transpiration and fresh yield of the single cross 704 forage corn cultivar. The applied treatments included the irrigation water salinity at three electrical conductivity levels of 1.8 (S0), 5.2 (S1), and 8.6 (S2) deci Siemens/meter (dS/m), which were prepared by mixing saline well water of the region with fresh (drinking) water and three water stress levels of 100% (W0), 75% (W1), and 50% (W2) of the plant's water requirement. The depth of soil moisture in the corn plant root zone was measured by the TDR device at five depths of 7.5, 12, 20, 40, and 60 cm during different growth stages of the plant using pairs of 7.5, 12, and 20 cm stainless steel electrodes.Results and DiscussionThe simultaneous water and salinity stresses, which led to the reduced amount of periodic evaporation-transpiration of the yield compared to ideal conditions (without stress), were simulated by additive and multiplicative models. The results suggested a decrease in the evaporation and transpiration with the increased simultaneous water and salinity stresses so that the amount of total evaporation-transpiration in different treatments was measured to be between 692.7 and 344.9 mm and the fresh yield was estimated between 50.4 and 3.2 tons per hectare. Also, the highest amount of periodic evaporation and transpiration in all treatments was found to occur in the development and intermediate stages, and the relative fresh yield in the W0S0 to W2S2 treatments was calculated between 66% and 100%. The results of modeling the relative yield of the crop based on the amounts of relative evaporation and transpiration of corn in different growth stages and under the different treatments of water stress and salinity, indicated that Singh's additive model and Rao's multiplicative model were appropriate, while the Minhas model was recognized to be inappropriate in this estimation.ConclusionThe research results suggested the significant impact of water stress and salinity at least at the 95% level on evaporation and transpiration and the corn yield. Moreover, the effect of the sensitivity of different growth stages of the plant on the reduction of evaporation and transpiration of corn varies so that in the three treatment groups W0, W1, and W2, the highest average decrease in slope was related to the final stage (13.6%) followed by the middle stage with an average decrease of 8.4% compared to the control treatment. Therefore, the highest decrease rate in evaporation-transpiration slope has been observed in these two growth stages due to the beginning of flowering, fruit formation, and physiological ripening of seeds. These results come from the lack of sufficient water storage and increased salinity of irrigation water in the soil. Water stresses and salinity will reduce water absorption and evaporation-transpiration, and ultimately, reduce crop production due to the decreased amount and potential of water in the soil. Another finding to be mentioned is the priority of water stress compared to salinity stress in reducing evaporation and transpiration and production yield. Also, by managing water and salinity stresses in the critical stages of plant growth (especially the middle stage), which is the time of flowering and the beginning and completion of the maize production process, a significant reduction in the crop can be somewhat prevented.
Irrigation
T. Khalili; M. Sarai Tabrizi; H. Babazadeh; H. Ramezani Etedali
Abstract
Introduction: Water resources management in arid and semi-arid regions is very important specially, in agricultural sector. The major share of water use is daily consumption by humans for drinking, washing and cooking. Furthermore, population growth increases agricultural production demand, and ...
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Introduction: Water resources management in arid and semi-arid regions is very important specially, in agricultural sector. The major share of water use is daily consumption by humans for drinking, washing and cooking. Furthermore, population growth increases agricultural production demand, and this highlights the role of water resources management in the agricultural sector. The 1950’s studies showed 12 countries with a population of 20 million experienced water shortage. Virtual water is the volume of water which is consumed for a production from the beginning stage to the end. Scientists have shown that 96% of water footprints are related to crops, livestock and horticultural productions and only 4% it consumed as domestic water. Water balance data in Qom province shows that 90% of water resources are using in the agricultural sector. Investigation of water footprints in the agricultural sector is highly beneficial to improve water resources management in arid and semi-arid regions such as Qom. Materials and Methods: The research was conducted to find out the production and cultivation water needs in the agricultural sector for 10 years, via calculating the gray, blue and green water footprints using Mekonnen and Hoekstra models. In the livestock sector, water footprint’s information such as the number of livestock and poultry, production of red meat, chicken meat, egg and milk were also determined using the Mekonnen and Hoekstra. The water footprint in fertilizer was calculated using a questionnaire survey. Excel and SAS apps were used to analyze the collected data for all three study sections. Results and Discussion: The results showed that the water footprint in wheat, barley, cotton, onion, tomato, melon, watermelon, alfalfa, and corn were 3018, 2882, 10960, 1463, 1525, 960, 2504, 1683 and 416 m3/ton, respectively. The low irrigation efficiency led to a very high amount of white water footprint in the productions. Green water footprint was very low due to the lack of rainfall. In the livestock sector, the water footprint in red meat and milk were 39 m3/kg and 2.42 m3/lit, respectively which were much more than the global average. In the poultry sector, the water footprint in chicken meat and egg were 7.4 and 4.34 m3/kg, respectively, that were very high compared to the global average. The water footprint in fertilizer for wheat, barley, cotton and alfalfa productions were 2.62, 1.19, 1.07 and 2.54 m3/kg and this amount was higher under nitrogen fertilizer. The average virtual water footprint for chicken meat production in Qom province was 7.4 m3/kg. This amount in the world, USA, India, Russia, Mexico and the Netherlands is equal to 3.92, 2.39, 7.74, 5.76, 5.01 and 2.22 m3/kg respectively. In Netherlands, less water is in use in the agricultural sector than the other countries. In this country, the virtual water footprint in chicken meat is in the best position. India has the highest water consumption in poultry breeding with a consumption of 7.74 m3/kg. The average virtual water footprint in Iran for egg production is 4.34 m3/kg , while the average virtual water footprint for egg production in the world, USA, India, Russia, Mexico and the Netherlands is 3.34, 1.51, 7.53, 4.92, 4.28, and 1.4 m3/kg, respectively. India consumes the most water in the production of eggs such as chicken with a quantity of 7.53 m3/kg and the Netherlands has the least consumption with a value of 1.4 m3/kg . Conclusion: The concept of virtual water footprint in each region reduces the pressure on water resources. For better management in agricultural regions, it is possible to prevent the cultivation of high water demand crops. The most common cause of high water footprint in livestock and poultry is nutrition, so, internationally food import can be a good solution. Industrialization of poultry can also reduce water footprint. The implementation of this research can be a useful clue to the sustainable control and management of water resources and achieving an optimal cultivation pattern in our country and all provinces facing limited water resources.
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.
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.
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.
H. Ramezani Etedali; Maryam Pashazadeh; B. Nazari; abbas sotoodehnia; A. Kaviani
Abstract
Introduction: Regarding population growth rate and drought challenges, one of the effective strategies for sustainable development in agricultural sector is irrigation. In this regard, in recent years, the use of tape irrigation method has been considered in crop plants, but the use of this system will ...
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Introduction: Regarding population growth rate and drought challenges, one of the effective strategies for sustainable development in agricultural sector is irrigation. In this regard, in recent years, the use of tape irrigation method has been considered in crop plants, but the use of this system will be successful if it is to evaluate the system performance in terms of soil sustainability before it is implemented and its problems are solved. Problems in the field of sustainable agriculture are saltinification of soil resources that the tape irrigation over time and due to the continuity of its use in cultivated land, especially in warm and dry areas due to global warming, climate change and decline of the atmospheric precipitation leads to salinity accumulation in the soil.
Materials and Methods: In order to investigate the distribution and changes of salinity of soil profile in the root development zone of wheat, maize, barley and tomatoes grown in Qazvin Plain with initial salinity of 1/5 dS/m and salinity of irrigation water 1 dS/m In hot and dry climate, a type of irrigation was used (strip drip) and during the 20 years of cultivation, the AquaCrop version 5 was used. The results of simulation output were analyzed by Minitab 17 and Excel 2007 softwares.
Results and Discussion: The results showed that in all previous stuides, the amount of salinity accumulated through the tape irrigation in the soil surface is greater, but in this study, due to the time effect on salt accumulation in the soil profile in the root development area, The maximum salt accumulation below the soil surface and at depths (0/5, 1/5, 0/5 and 0/16) meter of the total root development depth of each plant, respectively, for tomato, maize, barley and Wheat has occurred. It can be said that over time, accumulated salt on the surface of the soil evaporated, re-moved with irrigation and redistributed under the soil profile. Simulation results were obtained after statistical analysis with Minitab 17 and Excel 2007 software showed that in tomato and corn products, tape irrigation with irrigation water salinity of 1 dS/m resulted in significant increase in average salinity of The root development zone from 1/5 is 4 and 4/4 dS/m over the course of 20 years (correlation significance at 5% level) and sustainable utilization of soil resources is questioned, While the increase in average salinity of root development zone in wheat and barley products due to tape irrigation over the course of 20 years has risen from 1.5 to 2/03 and 2/02 dS/m, which is not noticeable and at the level of 5% is not significance. This can be attributed to rainfall during the growing season of wheat and barley, which led to salt salting from the root zone. The correctness of this theory was tested by the significance of the correlation between rainfall and salinity in the 5% level and proved to be. Therefore, it is recommended to wheat and barley with the ability to tolerate high soil salinity are placed in the top priority for local irrigation in hot and dry areas with limited atmospheric rainfall and limited water resources.
Conclusions: From the above results, it was observed that, in products such as maize and tomatoes, tape irrigation resulted in a significant increase in the mean salinity of the root development zone over time. However, the increase in average salinity of root development in wheat and barley products due to the tape irrigation is negligible and canceled over time. In other words, the cultivation of crops such as barley and wheat in areas with scarcity of water resources and soil salinity ensures sustainable land management. These results, while using water with salinity of about 1 dS/m, and soil cultivation with an average salinity of 1/5 dS/m, have been taken. Since comprehensive and practical research has not been done on long-term salinity changes and the use of tape irrigation, after the cultivation of important crops such as wheat, barley, corn, tomato, the results of this research can be used in conducting managerial guidelines, The selection and prioritization of the appropriate cropping pattern in the warm and dry areas will be beneficial with few atmospheric precipitations.
Farshid Ramezani; Abbass Kaviani; Hadi Ramezani Etedali
Abstract
Introduction: AquaCrop model was developed to simulate crop response to water consumption and irrigation management. The model is easy to use, works with limited input, and has acceptable accuracy. In this study, the data of an alfalfa field (as a perennial fodder plant) in the Iranian city of Ardestan ...
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Introduction: AquaCrop model was developed to simulate crop response to water consumption and irrigation management. The model is easy to use, works with limited input, and has acceptable accuracy. In this study, the data of an alfalfa field (as a perennial fodder plant) in the Iranian city of Ardestan was used to calibarate and validate the performance of AquaCrop model to simulate the crop productivity in relation to water supply and irrigation management.
Materials and Methods: The data of Fajr-e Esfahan Company farms of Ardestan County were used for calibration and validation of the AquaCrop model, simulating the alfalfa performance in different harvests and over different years. The farms are 1004 m above sea level and located in 33°2' to 33°30' North and 55°20' to 55°22' East. The farm under investigation included ten plots of alfalfa field, with an area of 280 hectares. The data of two plots were used for calibration and, two others used for validation.
Considering that alfalfa is a perennial plant, the data regarding the first harvest was defined as sowing, and transplanting was used to refer to the next harvests. Considering the physiological changes of plants over a year and during different harvests, the numerical value of different parameters, including primary vegetation, maximum vegetation, the depth of primary root development, the maximum depth of primary root development, crop coefficient, germination date, flowering, vegetation senescence, and physiological maturity, were defined for the model. The CRM, NRMSE, R2, and EF indices were used for verification of the calibration results. The CRM index determines the overestimation or underestimation of the model. The EF index is variable between 1 and 0, where 1 indicates optimal performance of the model. If all estimated and measured values were equal, the value of CRM and NRMSE would be zero, and EF would be one.
Results and Discussion:After calibration, validation was performed to examine the performance of the model. Hence, the actual performance rate for different harvests and the results of simulations were compared. Lower NRMSE value is indicative of high accuracy of the model in estimation of the performance. The value of CRM was mostly positive, showing the underestimation of the model in most of the simulations. The maximum performance happened during the first harvest year. The annual harvest decreased with an average rate of 1.2, compared to former years. The evaporation and transpiration rate was calculated by the model and the results were compared with potential evapotranspiration (FAO Penman-Monteith) and National Document of Irrigation (NET WAT). The reference crop evapotranspiration (ET0) had the highest value, and was calculated through FAO Penman-Monteith equation. The numerical value of potential crop evapotranspiration (ETc), which is the result of multiplication of crop coefficient by reference crop evapotranspiration (ET0), was greater than the results of the model, i.e. the estimated actual evapotranspiration. The discrepancy between them is the result of stress coefficient (ET0×Kc×Ks), which the model takes into account in estimation of actual plant water requirement. Evapotranspiration refers to two factors, namely the water lost by transpiration from plants and by evaporation from the soil. The plant transpiration and green cover are considered to be the generating part; AquaCrop is able to examine and improve transpiration efficiency through managerial statements. The values of transpiration from plants and evaporation from the soil for alfalfa were differentiated from the values estimated by the model. The productivity of evaporation, transpiration, and evapotranspiration were calculated by the model. The difference in the productivity values of the plots during different years was the result of difference in chemical composition, harvest index, and transpiration rate.
Conclusion:The AquaCrop model performed well in simulation of crop performance compared to actual annual, and even monthly, performance, and its results were very close to the actual performance. The model is sensitive to temperature changes, and it is suggested to use the Growing Degree Days (GDD) instead of Calendar Days section. . The Version 5 of AquaCrop model can, in addition to moisture stress, include salinity stress in calculations; this is evident in the variation of actual evaporation and transpiration values estimated by the model. In this study, the annual evaporation and transpiration rate was predicted by the model. The higher rate of evaporation can lead to a 27 to 44 percent decrease in the efficiency of evapotranspiration (Y ET-1), compared to transpiration efficiency (Y T-1).
reza saeidi; Hadi Ramezani Etedali; Amir Samadi; Ali Reza Tavakoli
Abstract
Introduction: Rainfed agriculture plays an important role in food production. In Iran, 6 million hectares of cultivated landsare rainfed. Moreover, about10% of raw agricultural products are being produced by rainfed agriculture. Yields of rainfed fields are decreased due to drought in recent years in ...
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Introduction: Rainfed agriculture plays an important role in food production. In Iran, 6 million hectares of cultivated landsare rainfed. Moreover, about10% of raw agricultural products are being produced by rainfed agriculture. Yields of rainfed fields are decreased due to drought in recent years in Iran. Supplementary irrigation is a suitable management to improve and enhance the yield of rainfed agriculture. Determination of appropriate time of supplementary irrigation is necessary in each region. But water allocation for this practice is the main challenge, because water resources are restricted. Therefore, water allocation management between irrigated and rainfedfields could be a viable strategy. Water resources for supplementary irrigation in rainfed fields are saved through deficit irrigation in irrigated lands or from rivers. The purpose of this study is optimum water allocation for supplementary irrigation in wheat and barley farms from rivers to around rainfed fields in Kamyaran region. In this study, supplementary irrigation is considered in three management methods of autumn irrigation, spring irrigation and both of them.
Materials and Methods:Kamyaran is located in Kurdistan province in west of Iran. The area of rainfed field is very vast in this region. Usually, rainfed fields are located in high slop lands and far from water resources in Kamyaran region. Supplementary irrigation is possible in rainfed fields around to water resources and with slope of less than 8%. The area of sub-basins with appropriate situations in Kamyaran region was calculated by geographic information system (GIS). Ratio of wheat to barley in rainfed fields is 3 to 1. Rivers in each sub-basin is the only water resources for supplementary irrigation in Kamyarn region. In this study, the objective function is maximizing net benefit. Also, constraints are total available water volumes in rivers at supplementary irrigations times and rainfed fields with appropriate situation for supplementary irrigation. Decision variable is rainfed area with different irrigation managements (autumn supplementary irrigation, spring supplementary irrigation, autumn+spring supplementary irrigations and rainfed managements). The total costs and income of agricultural production are found in statistical books of agriculture jihad in 2008-2009 growing season.
Results and Discussion: The lands around of rivers with suitable slope are about 30% of rainfed land of Kamyaran. The appropriate rainfed fields in sub-basins of A, B, C, D, E, F and INT were 125.39, 15.52, 18.11, 1111.26, 96.51, 48.13 and 49.55 Km2, respectively. The results of Optimization model showed the supplementary irrigation managements are different in each sub-basin because of different discharge of river in each sub-basin in different months. The optimal supplementary irrigation management for barley rainfed fields is autumnsupplementary irrigation. The yields of barley rainfed fields increase about 90% by autumn supplementary irrigation. The optimal supplementary irrigation managements for wheat are different in each sub-basin, but autumn+spring supplementary irrigations is best managed if water resources will be enough in each sub-basin. Due to restriction of water in rivers at supplementary irrigation time, some of wheat and barley fields remain rainfed in A+B+C and D sub-basin. The results showed minimum and maximum increase of wheat production in D and INT sub-basins are 29 and 134%, respectively. Also production increasing are 87, 112 and 126% in A+B+C, E and F, respectively. Increasing of barley production in the sub-basins of E, F and INT, are 61, 96 and 96%, respectively. Other sub-basins of A+B+C and D remained in rainfed farming. Net benefit increase about 65 and 275% for wheat and barley fields respectively, in 2014. Water productivity in all sub-basins for both wheat and barley is 74.8 and 44.5%, respectively.
Conclusions:This study showed supplementary irrigation management increased the yield and net benefit in rainfed fields of Kamyaran sub-basins. Resultsshowed about 30% of rainfed land of Kamyaran, are suitable for supplementary irrigation. The results of optimization models showed total increase of wheat production in A+B+C,E, F, D and INT sub-basins are 87, 112, 126, 29, 134%, respectively. Also increase of barley production in the sub-basins of E, F and INT, are 61, 96 and 96%, respectively. The result showed production increase about double in Kamayaran region. Also, net benefit increase about 65 and 275% in wheat and barley fields respectively.It has been suggested in A, B, C sub-basin, autumn supplementary irrigation of wheat, in E, F and INT sub-basins, autumn and spring supplementary irrigation for wheat and autumn supplementary irrigation for barley and in D sub-basin, autumn and spring supplementary irrigation for wheat.
Hadi Ramezani Etedali; Alireza Shokoohi; S. Amin Mojtabavi
Abstract
Introduction: Qazvin plain is one of the most important agricultural regions in the central part of Iran. Because of recent continuous droughts and the increases in the demands of different sectors such as agriculture, industry, environment and domestic, the plain is faced witha severe shortage of water ...
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Introduction: Qazvin plain is one of the most important agricultural regions in the central part of Iran. Because of recent continuous droughts and the increases in the demands of different sectors such as agriculture, industry, environment and domestic, the plain is faced witha severe shortage of water resources. Due to the declining share of surface waters, farmers increased the using of groundwater. And the overusing of groundwater for irrigation has caused the severe drop in water level of the aquifer. The critical situations in the Qazvin plain have made the agricultural water management and crop pattern modification vital and necessary.Due to the population increase, concepts and theories such as food security, environmental protection and sustainable management of groundwater and surface water resources, virtual water footprint and virtual water trading are a dynamic concept for water resource management in all sectors that has considered more in recent years.
Materials and Methods: The green (effective precipitation), blue (net irrigation requirement), gray (for diluting chemical fertilizers) and white (irrigation water losses) water footprints (WF) of main crop production were estimated for Qazvin plain. The average yield and fertilizer application in irrigated and rainfed lands, for main crops wasobtained from Agricultural-Jihad Bureau of Qazvin Province in for 2003-2014. Pe values were calculated by USDA method and ETc was calculated by FAO-Penman-Montieth method using the model CROPWAT. Values of α under irrigation and rain-fed were considered 5 and 10%, respectively. In this study, WFGray has been calculated just for nitrogen fertilizers. The maximum nitrogen concentration in the receiving waters based on the US-EPA Standard is 10 mg/lit. Due to the differences in crop yield under rainfed and irrigation conditions, the WF components were calculated using crop yield for different conditions, separately.
Results and Discussion: Canola and maize with 4066 and 185 m3/ton have maximum and minimum WF in the irrigated lands, due to the yield of two crops. Canola and maize have maximum and minimum yield between the irrigated crops, respectively. The total wheat WF of was estimated 2673 m3/ton in the area. The total WF in the rainfed lands is much more than the total WF in irrigated lands that is due to the significant yield differences in the irrigated and rainfed lands, especially for wheat and barley. In recent years, because of the decrease in precipitation, the rainfed crop yields have decreased considerably. Between the irrigated crops, wheat, barley, tomato, and canola are the four crops which have similar white WF (about 50%) and gray WF (about 10%). Also there are the same shares between white and gray WFs of corn and maize. The shares of white and gray WF in corn and maize are 28 and 18, respectively. These results show that agricultural practices and managements are similar. In other words, the irrigation system efficiency and fertilizer application are similar in farms and for crops. Also there aren’t significant differences in the green and blue WFs of corn and maize. These similarities in WF components are the result of approximate equalities in the evapotranspiration, effective rainfall, fertilizer application, and depth of irrigation. In irrigated lands, white WF contains about 46% of the total water footprint in the production of main crops. In irrigated and rainfed lands, about 42% of the WF is related to white water. Thus, irrigation losses are about 864 MCM/year in the region, which is really considerable for a region that faced with water shortage crisis. In rainfed lands, the gray WF component is about 13. In total. If this gray WF which is the environmental need for protecting water quality doesn’t meet, contamination of surface and groundwater resources will be occurred. Wheat has the most consumed and exported virtual water volume with 652 and 343 MCM/year, respectively. The export of wheat includes 28.4% of the total exported virtual water volume and 20.2% of the exported water resources volume. Total consumed and exported virtual water volume from the region are 1031 and 1022 MCM/year. The exported volume of blue, gray and white WFs consists about 783 MCM/year. Therefore, considerable volumes of groundwater and surface water resources exported from the region by exporting main crops. The exported weight of maize, corn, alfalfa and tomato from the region is greater than the weight of consumption in the region. The total of blue, gray and white WFs is much higher than the green WF of these crops. The export of these crops imports the most pressure on groundwater and surface water resources of the region.
Conclusions: Qazvin Plain as one of the most important plains in the central part of Iran faces to water shortage crisis. The concept of virtual water and WF of agricultural production help to better agricultural water management in the region. The total share of gray and white WFs in the region is about 907.5 MCM/year and 44% of the total WF in the agricultural main crop production. Low efficiency of irrigation systems and excessive use of nitrogen fertilizers in farms are the most important causes of high shares of these two WF components. The planting and export of summer crops hasa considerable share of VW trade in the region. Due to the high water requirements, the total share of blue, gray and white WFs is high in these crops. These WF components are supplied from the limited surface and groundwater resources of the region. Also, WF in rainfed crops is much greater than the irrigated crops. Droughts and rain reduction are the main reasons of severe decreasing in the yield of rainfed lands. Supplementary irrigation is a management for reducing WF and improving yield in rainfed land. VW trade volume is about 1,022 MCM/year.
B. Ababaei; H. Ramezani Etedali
Abstract
Introduction: Water use and pollution have raised to a critical level in many compartments of the world. If humankind is to meet the challenges over the coming fifty years, the agricultural share of water use has to be substantially reduced. In this study, a modern yet simple approach has been proposed ...
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Introduction: Water use and pollution have raised to a critical level in many compartments of the world. If humankind is to meet the challenges over the coming fifty years, the agricultural share of water use has to be substantially reduced. In this study, a modern yet simple approach has been proposed through the introduction concept ‘Water Footprint’ (WF). This concept can be used to study the connection between each product and the water allocation to produce that product. This research estimates the green, blue and gray WF of wheat in Iran. Also a new WF compartment (white) is used that is related about irrigation water loss.
Materials and Methods: The national green (Effective precipitation), blue (Net irrigation requirement), gray (For diluting chemical fertilizers) and white (Irrigation water losses) water footprints (WF) of wheat production were estimated for fifteen major wheat producing provinces of Iran. Evapotranspiration, irrigation requirement, gross irrigation requirement and effective rainfall were got using the AGWAT model. Yields of irrigated and rain-fed lands of each province were got from Iran Agricultural-Jihad Ministry. Another compartment of the wheat production WF is related about the volume of water required to assimilate the fertilizers leached in runoff (gray WF). Moreover, a new concept of white water footprint was proposed here and represents irrigation water losses, which was neglected in the original calculation framework. Finally, the national WF compartments of wheat production were estimated by taking the average of each compartment over all the provinces weighted by the share of each province in total wheat production of the selected provinces.
Results and Discussion: In 2006-2012, more than 67% of the national wheat production was irrigated and 32.3% were rain-fed, on average, while 37.9% of the total wheat-cultivated lands were irrigated and 62.1% was rain-fed from more than 6,568 -ha. The total national WF of wheat production for this period was estimated as 42,143 MCM/year, on average. Different compartments of wheat WF were estimated for 236 plains in fifteen selected provinces. For irrigated areas, the green WFs ranged from 499 to 1,023 m3/ton, the blue WFs from 521 to 1,402 m3/ton, the gray WFs from 337 to 822 m3/ton, and the white WFs from 701 to 2,301 m3/ton. The average total WF for irrigated areas among all the selected provinces is about 3,188 m3/ton, with almost equal shares of blue and green water. For rain-fed areas, the green WFs ranged from 1,282 to 4,166 m3/ton and the gray WFs from 100 to 740 m3/ton. The average total WF for rainfed areas is about 3,071 m3/ton with the share of green WF being nine times the gray WF. In irrigated areas, the percentages of green, blue, gray and white WFs are 23, 25, 17 and 35% of total WF, respectively in each province. The average total WF for irrigated areas is about 3,188 m3/ton with comparable shares of blue and green water. In irrigated areas, Fars, Khorasan and Khuzestan provinces have the largest of the total WF with 5,575, 5,028 and 4,123 MCM/year, respectively. In addition to large cultivated areas and high rates of potential evapotranspiration, high values of gray and white water is another reason for the high volume of total WF in these provinces.
Conclusions: The results showed that the green WF related about wheat production in our country is about 2.3 times the blue WF. It confirmed the importance of green water in wheat production. Also the gray water footprint was assessed which is related about nitrogen application. Besides, the white water footprint was proposed here, which represents irrigation water losses. Results showed that the total water footprint in wheat production for the whole country is about 42,143 MCM/year on average over the period of 2006-2012. The ratios of green, blue, gray and white water were 41, 18, 16 and 25%, respectively. Different compartments of wheat WF were estimated for 236 plains over fifteen selected provinces. Total shares of gray and white water footprint were 41% of total wheat production water footprint. The average total WF for irrigated areas among all selected provinces is about 3,188 m3/ton, with almost equal shares of blue and green water. The authors admit that the accuracy of these results is subject to the quality of the input data.
H. Ramezani; B. Nazari; A.R. Tavakoli; M. Parsinejad
Abstract
Abstract:
Deficit irrigation technique can be used for produce more yield for every unit of irrigation water, and cause to increase crop economical benefit. Main purpose of deficit irrigation is high water use efficiency with decreasing in irrigation sufficiency. In this research potential of CROPWAT ...
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Abstract:
Deficit irrigation technique can be used for produce more yield for every unit of irrigation water, and cause to increase crop economical benefit. Main purpose of deficit irrigation is high water use efficiency with decreasing in irrigation sufficiency. In this research potential of CROPWAT model in deficit irrigation management for two crops, wheat and barley in Karaj climate was studied. The results of reliability index such as RMSE and CRM with about are 9.8-17.2 percent and 0.32-0.51 value respectively, showed that the model in both crops underestimated the yield reduction compared with actual data. Negative values of EF index achieved for both crops with 14 days irrigation interval show inefficiency of model in yield reduction predicting in this irrigation interval. This difference was more obvious in deficit irrigation treatments. Considering only drought stress and neglecting other stresses -such as salinity- is the most important limitation of CROPWAT model. Model crop coefficients could also caused differences between actual data and model results. This study shows that application of CROPWAT model without calibration of crop coefficients and soil characteristics would be result in significant errors and this is should be considered. In this study water use efficiency for studied crops were achieved in the range of 1.3-2.3 Kg/m3 and maximum values of that was in 20% deficit irrigation. Applying optimum deficit irrigation management could have considerable role in increasing water use efficiency.
Keywords: Water use efficiency, Yield reduction, Production function, CROPWAT
H. Ramezani; A. Liaghat; A.A. Naseri
Abstract
Abstract
Drainage water created from irrigation and drainage projects in south of Khuzestan province are saline and its disposal to rivers such as Karoon river is faced with certain constraints. One of drainage water disposal strategies is using evaporation ponds, in which the most important outlet ...
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Abstract
Drainage water created from irrigation and drainage projects in south of Khuzestan province are saline and its disposal to rivers such as Karoon river is faced with certain constraints. One of drainage water disposal strategies is using evaporation ponds, in which the most important outlet is evaporation. Evaporation rate of saline water of these ponds is lower than fresh water. In this study the evaporation rate of implicit ponds for drainage water control in Mirza Kuchak Khan Project was estimated by adjusting the saturation vapor pressure equation of saline water with regard to pure water and by using of Penman equation. Finally, using the evaporation and the annual drain water volume, the required area of evaporation ponds was determined. By evaporation of water from ponds the salinity of water increases. This increase of salinity continues until the salt saturation threshold is reached, and then salts precipitate. The most common salt in drainage water of Khuzestan province is NaCl which has a saturation threshold of 300 g/lit. The results showed that the average annual evaporation of water with 300 g/lit salt is 1903 mm. The drainage water volume produced from Mirza Kuchak Khan Project (12,000 ha area), requires evaporation ponds as big as 7740 ha. This study showed that disposal of the drainage water of sugarcane projects is impossible if only evaporation ponds are used, and therefore, other management options should be considered for reducing the volume and salinity of drainage water.
Key words: Evaporation ponds, Drainage water, Khuzestan, Salinity