Irrigation
Nader Karimi; Sayyed-Hassan Tabatabaei; Mohammad Hassan Rahimian; Seyyed Alireza Esmaeilzadeh Hosseini
Abstract
Introduction In arid and semi-arid regions, agricultural sustainability needs to improve the consumption of water and soil resources. Low rainfall, high evaporation, low water quality and less leaching of solutes in the soil due to limited water resources are the main problems in these areas. The ...
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Introduction In arid and semi-arid regions, agricultural sustainability needs to improve the consumption of water and soil resources. Low rainfall, high evaporation, low water quality and less leaching of solutes in the soil due to limited water resources are the main problems in these areas. The quality of water and soil resources in the provinces of Fars, Khuzestan, Yazd, Golestan and Khorasan also shows that most of the wheat farming lands in these provinces are always facing salinity issues. According to the conducted studies, saline water can be successfully used in irrigation, but application of unconventional water by surface irrigation systems with low efficiency due to evaporation and high water salts leads to soil salinity. Micro-irrigation methods increase water use efficiency by reducing water consumption and increasing yield, so that drip irrigation efficiency of 91-80% and irrigation levels of 50-73% have been reported. In recent years, the use of drip irrigation system (such as tape on wheat fields) has been recommended to farmers as a water management solution. Micro-irrigation systems by reducing water consumption and increasing yields, improve water use efficiency. Drip tape irrigation system compared to other surface and sprinkler irrigation methods, due to short irrigation periods and reduction of evaporation losses and deep infiltration even for crops can be proposed as an alternative. Drip tape irrigation in wheat cultivation can increase water use efficiency up to 2 times. Also, in irrigation with salt water, while maintaining humidity in the environment, it reduces salinity stress and by consuming less water and reducing the amount of wetting, it introduces less solutes into the soil. This method has limitations in wheat fields due to costs and also the possibility of soil salinity problems, some of which can be overcome by increasing the distance between the laterals and reducing the consumption of drip irrigation (Tape) per unit area.Materials and Methods In this study, during the 2020-2021 at the Salinity Research Center of Yazd Province (Iran), the effect of lateral distances on the surface and depth distribution of soil salinity was investigated. For this purpose, two irrigation water salinity treatments, including 3 and 8 dS / m and two flood (T1) and drip irrigation systems (Tape) with lateral distances of 60 (T2), 100 (T3) and 140 (T4) cm were considered. Irrigation management treatments included the use of the flooding method (as the dominant method in wheat fields) and the use of the Tape drip irrigation method (as the proposed method with very low water consumption). A distance of 60 cm was considered as the optimal distance with complete water overlap, a distance of 100 cm was considered as an economic distance with the possibility of deep moisture distribution and a distance of 140 cm was considered as a large lateral distance. To investigate the salinity distribution and the accumulation of salts in the soil, regular soil sampling of different treatments was the end of the season.Results and Discussion In all irrigation treatments (saline and non-saline), despite the constant volume of water consumption per unit area of all treatments, in T3 and T4 treatments, irrigation depth increased compared to T2 treatment and reduced soil salinity in the wetting area (irrigated area). By increasing the horizontal distance of each point of the field from the lateral, the irrigation depth and leaching fraction decrease and consequently, the soil salinity of these points can also increase. Under non-saline irrigation conditions (salinity of 3 dS/m), soil salinity at intervals of zero (below the lateral), 15 and 30 cm, between 5.5 and 6.1 dS/m has been observed. Values below the threshold of tolerance to salinity of wheat plant and, in this regard, does not pose a risk to the plant. At a distance of 45, 60 and 70 cm from the water pipe, the salinity of the soil is higher than the threshold and if there is a plant in this area of the field, it will face serious damage.Conclusion The results showed that although the Tape method in saline conditions (8 dS/m) compared to non-saline conditions (3 dS/m) leads to higher accumulation of solutes in the soil and increases the possibility of plant damage, but according to the final results of this study, by increasing the distances of irrigation laterals and proportionally increasing the depth of irrigation and keeping the salts away from the planting bed, a more suitable environment for plant growth can be prepared and higher economic benefits of this measure can be obtained. Also, in terms of controlling soil salinity, the conditions have been such that treatment with lateral distance of 140 cm compared to treatments of 60 and 100 cm has led to lower amounts of soil salinity in the subsurface and has provided better conditions for the plant. Thus, by increasing the distances of laterals from 60 to 140 cm and, consequently, increasing the depth of irrigation, it was possible to transfer solutes to lower depths of the soil.
Aida Mehrazar; Jaber Soltani; omid Rahmati
Abstract
Introduction: Limited water resources and its salinity uptrend has caused reducing water and soil quality and consequently reducing the crop production. Thus, use of saline water is the management strategies to decrease drought and water crisis. Furthermore, simulation models are valuable tools for improving ...
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Introduction: Limited water resources and its salinity uptrend has caused reducing water and soil quality and consequently reducing the crop production. Thus, use of saline water is the management strategies to decrease drought and water crisis. Furthermore, simulation models are valuable tools for improving on-farm water management and study about the effects of water quality and quantity on crop yield.. The AquaCrop model has recently been developed by the FAO which has the ability to check the production process under different propositions. The initial version of the model was introduced for simulation of crop yield and soil water movement in 2007, that the effect of salinity on crop yield was not considered. Version 4 of the model was released in 2012 in which also considered the effects of salinity on crop yield and simulation of solute Transmission in soil profile.
Material and methods: In this project, evaluation of the AquaCrop model and its accuracy was studied in the simulating yield of maize under salt stress. This experiment was conducted in Karaj, on maize hybrid (Zea ma ys L) in a sandy soil for investigation of salinity stress on maize yield in 2011-2012. This experiment was conducted in form of randomized complete block design in four replications and five levels of salinity treatments including 0, 4.53, 9.06, 13.59 and 18.13 dS/m at the two times sampling. To evaluate the effect of different levels of salinity on the yield of maize was used Version 4 AquaCrop model and SAS ver 9.1 software .The model calibration was performed by comparing the results of the field studies and the results of simulations in the model. In calculating the yield under different scenarios of salt stress by using AquaCrop, the model needs climate data, soil data, vegetation data and information related to farm management. The effects of salinity on yield and some agronomic and physiological traits of hybrid maize (Shoot length, root length, dry weight and crop yield) under different levels of NaCl solution osmotic potential were also investigated by SAS ver 9.1 software. Data's mean comparisons were performed by Duncan's multiple range test. To assess the accuracy of AquaCrop Model for Simulation of the Maize Performance under Salt Stress used from Indicators RMSE, MAE, CRM, NSE, d and Er.
Results Discussion: The results of RMSE and MAE indices showed that AquaCrop model can simulate maize yield under the salinity stress. Accuracy decreased and crop yield prediction underestimated with increasing salinity from treatment 0 to 18.13 ds/m in the first and second harvest. The highest yield related to salinity treatment of 0 dS/m and the lowest yield related to salinity treatment 18.13 dS/m. yeild simulation error increased by increasing salinity, the highest and lowest error of yield simulation in model respectively related to salinity treatments 18.13 and 0 dS/m. The highest and lowest error was in the first harvest respectively 0.56 and 13.1 percent and in the second harvest respectively 0.42 and 21.79 percent, that in the comparison with the results of studies conducted by Steduto and colleagues on maize is not much different. The results comparison in the first and second harvest showed that soil salinity was increased by increasing irrigation number in second harvest, so the error in second harvest is greater than first harvest and the maximum error is related to treatment 18.13 ds/m in the second harvest 21.79 percent.The coefficient of determination R2 for the first and second harvest is respectively 0.850 and 0.834, that indicates a high correlation between yeild values of measured and predicted by the AquaCrop model. CRM index was negative and near zero in both harvest under Salinity different scenarios. According to CRM value, AquaCrop model was overestimated and the model was simulated maize yield under the salinity stress a little more than measured yield. The d statistic index value is close to unity, indicates that yield values in model is compatible with actual values. NSE index was calculated for the first and second harvest respectively 0.81 and 0.84, that is close to one and showed that the model has suitable performance in the yield simulation. Comparison of means by Duncan's multiple range test and analysis of variance in the software SAS ver 9.1 indicated Salinity has a very significant effect on all traits including shoot length, root length, dry weight and crop yield that all traits were decreased significantly by increasing salinity.
Conclusion: Comparison of the results of AquaCrop model and statistical analysis in software SAS ver 9.1 showed that maize yield was reduced with increasing salinity. According to index CRM, AquaCrop model was simulated maize yield under the salinity stress more than measured yield in farm. The results showed that the AquaCrop model simulated well maize yield in moderate and low stress, but accurately simulation slightly decreased in high stress. The results of this study was compared with other research and indicated that the error values of AquaCrop model in Karaj is not much different with the error values of other research.
A. Kiani; A. Hezarjaribi; T. Dehghan; M. Khoshravesh
Abstract
Introduction: Water scarcity is one of the major problems for crop production. Using drip irrigation as an effective method in the efficient use of water is expanding in arid and semi-arid regions. One of the problems in under pressure irrigation during use of saline, unconventional and waste is emitters ...
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Introduction: Water scarcity is one of the major problems for crop production. Using drip irrigation as an effective method in the efficient use of water is expanding in arid and semi-arid regions. One of the problems in under pressure irrigation during use of saline, unconventional and waste is emitters clogging. There are several ways to prevent particle deposits in pipes and clogging of emitters. Generally, conventional methods are divided into two categories: physical and chemical methods. In physical method, suspended solids and inorganic materials are removed using particles sediment sand and disc filters. In the chemical method the pH drops by adding acid to water resulting in the dissolution of carbonate sediments. With chlorine handling, organisms (i.e. algae, fungi and bacteria) that are the main causes of biological clogging are destroyed. However, the application of these methods is not successful in all cases. It has been observed that the emitters have gradually become obstructed. Magnetic water is obtained by passing water through permanent magnets or through the electromagnets installed in or on a feed pipeline. When a fluid passes through the magnetized field, its structure and some physical characteristic such as density, salt solution capacity, and deposition ratio of solid particles will be changed. An experimental study showed that a relatively weak magnetic influence increases the viscosity of water and consequently causes stronger hydrogen bonds under the magnetic field.There exist very few documented research projects related to the magnetization of water technology and its application to agricultural issues in general and emitter clogging in drip irrigation method, in particular. This technology is already used in some countries, especially in the Persian Gulf states. This research was designed and implemented aimed at increasing knowledge about the application of magnetic technology and its effects on emitters clogging in the drip irrigation system.
Materials and Methods: A field experiment was carried out in 2011 in Gorgan Agricultural Research Station to study emitter clogging in drip irrigation using magnetic, non-magnetic and acidic water under salinity condition. The geographical location of the farm was 36° 55′ N, 54° 25′ E and 13.3 m above mean sea level with annual rainfall 400-450 mm. The experiment was laid out with a split plot in a complete randomized block design with three replications. The treatments included three treatments of the management of emitters clogging including, magnetized water (M), non-magnetized water (N) and acidic water (A) plus using three water quality levels namely, well water (S1), saline waters 7 (S2) and 14 (S3) dS m-1. Two methods were simultaneously used to magnetize water. In the first method, an electromagnet was installed around the sub-main pipe before the flow of water to the laterals. The amount of power required to magnetize the irrigation water was 0.03 kW-h of electricity per m3 of water. In the second method, the permanent magnets (ceramic magnets) were installed around the sub-main pipe before the laterals. In the second method the power requirement was 0.3 Tesla. To assess the emitter clogging, discharge and its variations as a function of time, emission uniformity, uniformity coefficient, and coefficient of variation were estimated and analyzed.
Results and Discussion: The results of variance analysis showed that the effect of different irrigation management in irrigation system (N, M and A treatments) and different levels of water quality on all parameters were significant. Statistical comparison showed that in all cases there were no significant differences between magnetized water and non-magnetized water treatments. However, acidic water was statistically different from the two types of water mentioned. Both magnetic and conventional indices were examined in this study. However, no significant difference was observed. But in all cases, using magnetic water is advantageous compared with using non-magnetized water. The overall results have shown that the use of magnetized water in this study, in the non-saline water condition, does not offer a relatively higher advantage compared to the use of non-magnetized water.
Conclusion: For saline water, insignificant differences were observed between magnetic and non-magnetic water treatments, however magnetic water was slightly preferable. Most of the indicators that were assessed showed that acid water treatment was significantly different from magnetic and non-magnetic water treatments. Thus, acid water treatment is not preferable. Emitter clogging with increase of time and the salinity level of irrigation water increased; the greatest difference between the treatments occurred in S3 and the last irrigation treatments. Magnetic water up to salinity level of 7 dS m-1, had no effect on the flow rate and thus on the emitter clogging. However, when using saline irrigation water and also with the increase of time, emitter clogging in magnetic water treatment was lower compared with non-magnetic treatment.
Keywords: Emitters clogging, Magnetized water, Saline water
