الفهرس | Only 14 pages are availabe for public view |
Abstract Due to the limited and the stability of Egypt’s water resources, and climate change, population growth, which requires the provision amounts of irrigation water, so you must adjust the amount of water and the quantities of fertilizers used in agriculture, through the use of irrigation automated systems and identify water and fertilizer amounts by scheduling mechanism for the provision of quantities of water horizontal expansion, as well as reduce deep percolation. It is known that in a drip irrigation system is a direct correlation or positive relationship between the operating pressure and the emitter flow rate. This relationship may be affected by some changes in the physical properties of water, one of these changes is to increase the proportion of salt, which are usually found in low-quality water where salt degrees vary with water depending on the purpose, which was used the water by, or that the source is the sea salt. This study aimed to: 1) Laboratory experiment studied the influence of different water salinity on the performance of five emitter types. 2) Study the influence of various operation pressures on the performance of selected emitters. 3) Recommend the three better of the emitter types to be applied in the field. 4) Study the influence of water salinity on the hydraulic characteristics of emitters. 5) Evaluate the effect of water salinity and emitter type on the growth and yield of turnip crop. Laboratory hydraulic experiment was carried out at water Relations and Field Irrigation Dept., (NRC) to evaluate hydraulic performance for five emitter types and selected the best to applied in the field experiment, whichapplied in Research and Research and Production Station, NRC, Nubaria, ElBeheara Governorate, Egypt, 2015/2016 season to study the effect of the selected emitters types under different irrigation water salinity on the hydraulic properties of the drip irrigation system, plant growth characters and yield of turnip crop. Lab experiments were conducted to evaluate hydraulic parameters for five emitter types [On-line emitter NEIN-ETF (NPC1), Built in GR (NPC2), pressure compensating emitters NEIN-PC (PC), Pressure compensating and Self-flushing emitter EDEN-PC (PCS)and On-line Commercial Katif emitter KATIF-R-P-201 (NPC3)] under water salinity (345, 2000, 4000, 6000; 8000 ppm) and different operation pressure heads (0.8, 1.0, 1.2, 1.4,1.6, 1.8; 2 bar). While in field experiment which was carried out to study the effect of some selected emitters (NPC1, NPC2, and, NPC3) under different water salinity, (2000 and 4000 ppm in addition to the canal water, 345 ppm) on the plant growth characters and yield of turnip (Brassica rapa L). The obtained results as follows: There is a positive relationship between the operating pressure and the emitter flow rate. Regarding the effect of operation pressure on the flow rate of the different studied emitters (NPC1, NPC2, PC, PCS, and NPC3), one can notice that increasing operation pressure associated with the increasing emitters flow rate. It is worth to mention that the rate of increase flow rate as affected by operation pressure were 4- 9- 14, 3- 5- 8 and 3, 5, 9 % in same sequences, if we compare the emitter flow rate at 1, 1.2; 1.4 bar comparing with 0.8 bar. The effect of emitter type on the coefficient of variation (CV) under (1.0 bar) as a nominal pressure head, one can notice that for, the ranked of emitter type were NPC1>NPC3>NPC2>PC>PCS. Emitters PCS and PC were the worthy ones that dramatically decreases their flow rate with increasing water salinity. from the other side, NPC1and NPC3 were the most suitable and moderately affected by water salinity followed by NPC2.It was observed that NPC1 followed by NPC2 and lastly NPC3 were not affected strongly by increasing water salinity. Water movement and distribution pattern differ regarding the irrigation method, especially under drip irrigation compared with other surface irrigation method. Under drip irrigation, in addition to its high application frequency, water is applied at separated points on the surface of the soil rather than over the total area, so the soil is wetted in a cone shape like axially symmetric pattern rather than in one-dimensional fashion. With low flow rate, water moves in a vertical direction that results in higher moisture adjacent to the emitter location. The wetting patterns under the emitters are characterized by the depth of wetting front under emitter and the radial wetting front at the surface. Under irrigation with saline water (2000 and 4000 ppm) resulted in relatively low salinity levels in the area extending downward from the emitter and larger salt accumulation in the areas among emitter and close to the front of the bed for the investigated soil.The low salinity water extended further horizontally in the soil profile, while it is flat and moderately flat relative to the moisture content in different soil layers before irrigation. According to AE% values, there were no significant differences among the tested emitters. Regarding AE% for NPC1 emitter, it recorded the highest value (91.74 %), while NPC3 counted the lowest AE% (90.94). Water amount applied to the crop during the growth season varied from 1824 m3/fed to 1907 m3/fed at operation pressure 1 bar.Comparing WUE for examined emitters, NPC1 had a primitive effect and recorded 14.5 and 17.4 % more thanNPC2 and NPC3 respectively. The impact of the investigated two parameters (water salinity and emitter’s types) had a promise value or accepted trend. DU values were more constant under different emitters and there was no high difference within salinity treatment of each emitter. The highest and lowest values of DU at 1.0 bar were recorded at (345 ppm) and the lowest one was recorded at 2000 ppm followed by 4000 ppm.According to water use efficiency as affected by water salinity and emitter’s type of turnip crops, it’s clear that NPC1 emitter recorded the highest value which ranged from 18.12 ton/fed (4000 ppm) and 23.43ton/fed (354 ppm) and 12.8; 9.1 kg/m3for 345 and 4000 ppm, respectively at 1 bar operation pressure. While comparing WUE for examined emitters, NPC1 recorded 14.5 and 17.4 % more thanNPC2 and NPC3 respectively. |