A computer model EUSS (Emission Uniformity on Sloping Surfaces) has been developed to design and evaluate the system capacity under operating conditions for drip irrigation system. And achieve the desired value of emission uniformity that is not significantly different according to the recommended values by applying it in field experiment located at Al- -Slahia city, Egypt. The model has the ability to design the system by all of the common design techniques and have ability to customize any of them.
EUSS model includes two main parts: crop water requirements, and hydraulic calculations of the system using metric unit system. It developed in graphical user interface of the programming language C-sharp (C#) by using Microsoft Visual Studio. The model database is containing the equations, tables and reference values to get more rapid and accurate results, and gives the opportunity for selecting some parameters such as: soil properties, characteristics of the corresponding crop, and climatic data. EUSS model allows the user to assume or set definite values, for example plot layout, land slopes and topography, the emitter characteristics and operating conditions.
CropSyst (Cropping Systems Simulation) is used as an analytic tool for studying irrigation water management to increase wheat productivity. Therefore, two field experiments were conducted to 1) calibrate CropSyst model for wheat grown under sprinkler and drip irrigation systems, 2) to use the simulation results to analyse the relationship between applied irrigation amount and the resulted yield and 3) to simulate the effect of saving irrigation water on wheat yield. Drip irrigation system in three treatments (100%, 75% and 50% of crop evapotranspiration – ETc) and under sprinkler irrigation system in five treatments (100%, 80%, 60%, 40%, and 20% of ETc) were imposed on these experiments. Results using CropSyst calibration revealed-that results of using CropSyst calibration revealed that the model was able to predict wheat grain and biological yield, with high degree of accuracy. Using 100% ETc under drip system resulted in very low water stress index (WSI = 0.008), whereas using 100% ETc sprinkler system resulted in WSI = 0.1, which proved that application of 100% ETc enough to ensure high yield. The rest of deficit irrigation treatments resulted in high yield losses. Simulation of application of 90% ETc not only reduced yield losses to either irrigation system, but also increased land and water productivity. Thus, it can be recommended to apply irrigation water to wheat equal to 90% ETc to save on the applied water and increase water productivity.
Improving water productivity (WP) through deficit irrigation is crucial in water-scarce areas. To practice deficit irriga-tion, the optimum level of water deficit that maximizes WP must be investigated. In this study, a field experiment was con-ducted to examine WP of the three treatments at available soil water depletion percentage (����) of 25% (reference), 45% and 65% using a drip irrigation system. Treatments were arranged in a randomized complete block design. The water deficit was allowed throughout the growth stages after transplanting except for the first 15 days of equal amounts of irrigations during the initial growth stage and 20 days enough spring season rainfall during bulb enlargement periods. Physical WP in terms of water use efficiency (WUEf) for treatments T1, T2, and T3 was 9.44 kg∙m–3, 11 kg∙m–3and 10.6 kg∙m–3 for mar-ketable yields. The WUEf and economic water productivity were significantly improved by T2 and T3. The WUEf differ-ence between T2 and T3 was insignificant. However, T2 can be selected as an optimal irrigation level. Hence, deficit irriga-tion scheduling is an important approach for maximizing WP in areas where water is the main constraint for crop produc-tion. The planting dates should be scheduled such that the peak water requirement periods coincide with the rainy system.
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