الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Several field trials were conducted in different locations along Nekla canal.Elbehara Gov. Three representative mesqas, (Arfa Mousa at the head, Elafeer2 at the middle and Elbanna at the tail) were selected to evaluate the impact of the implementation of the activities and processes of field irrigation system development on soil and irrigation water characteristics. crop yield, water saving, water productivity, water and salt balance and in consequently on rationalizing the use of water resources were also taken in evaluation.
The activities and processes of the development of the on-farm system include the conversion of the unlined canals to buried pipes operating under water pressure or to lined canals. The transition from multiple lift points to a single lifting point at the mouth at the head of the mesqa and the replacement of the hand control gates to the mechanical control gates for each canal feeder. In addition to the replacement of combined water lifting machines with diesel or electric lifting machines. The development of field irrigation system extended to the formation of water users’ associations at the branch canal level and the water council at the main canal level.
Effects of irrigation system development on water and soil properties
Results revealed slight decreases in pH and EC of water samples taken from the three tested mesqas as affected by field irrigation system development, where the mean values decreased from 8.18 to 7.99 for pH and from 0.57 to 0.54 dS/m for EC. The lowest pH value was observed in water samples taken from Eafeer2 mesqa after field irrigation system development. Similar trend was also observed for soluble Ca2+, Mg2+. This may be due to a reduction in canal water contamination after development. No specific trend was observed for changes in Na+, K+. Cl- and SO4= values after development compared with pre-development values.
Data indicated that the soil irrigated from Nekla canal is not saline or alkaline were soil salinity levels (ECe) less than 4 dS/m and the pH values were below 8.5 in. The values of soil pH, ECe, Ca2+, Mg2+, Na+, K+. HCO3-, Cl-, and SO4= slightly decreased as affected by field irrigation system development. These decreases were more pronounced in the lower layers of the tested soil profiles. Therefore, the heighest values of the most soil chemical analyses were found in the surface soil layers either before or after field irrigation system development.
The values of pH and ECe ranged from 8.03 to 8.23 and from 2.51 to 1.77 dS/m before development and from 8.14 to 7.78 and from 1.91 to 1.37 dS/m after field irrigation system development respectively.
The expected increases in soil salinity particulerely in the soil surface (0-15 cm) as a response to field irrigation system development were not yet observed. However, the soil chemical properties needs more time to change or affects by field irrigation system development.
Effects of irrigation system development on crop water consumptive use (WU) and applied irrigation water (AIW).
Data revealed that the number of irrigations were equal for each crop during growth season either irrigated from Arafa Mouse, Elafeer2, or Elbanna mesqas. It could be also observed the differences in the irrigation water applied (AIW) by the farmer for all crops before and after field irrigation system development. These differences increased with increasing crop water consumptive use (WU) during growth season. The applied irrigation water (AIW) clearly decreased for all crops after field irrigation system development. The heighest diference between applied irrigation water (AIW) before and after field irrigation system development was observed foe rice while the lowest diference was observed for wheat crop.
The applied irrigation water during growth season for wheat, rice, Egyptian clover, cantaloupe and watermelon pulp were ranged between 2169-2029, 6417-5592, 3408-2960, 2329-2072 and 1295-1161 for crops irrigated from Arfa Mousa at the head, 2224-2058, 6406-5589, 3407-2961, 2355-2089 and 1218-1077 for crops irrigated from Elafeer2 at the middle and 2184-2006, 6500-5652, 3504-2989, 2291-2291 and 1222-1128 m3/Fad for crops irrigated from Elbanna mesqa at the tail of Nekla canal before - after field irrigation system development respectively.
As expected, all the estimated values of water consumption of different crops are less than that of the values of applied irrigation water by the farmer himself during the growing season. In fact, irrigation efficiency is usually reach to the highest whenever the difference between the estimated values of water consumption and applied irrigation water during different stages of growth is in minimal.
Seasonal crop water consumptive use for wheat, rice, Egyptian clover, cantaloupe and watermelon pulp irrigated from the head (Arfa Mousa mesqa) were 1422-1465, 2976-2925, 2075-2036 1356-1376 and 822-795. While the WU by the same crops irrigated from the middle (Elafeer2 mesqa) were 1404-1438, 2944-2936, 2069-1977, -1373-1396 and 840-837 and 1438-1425, 2964-2943, 2041-2074, 1343-1325 and 789-845 m3/Fad for crops irrigated from the tail (Elbanna mesqa) of Nekla canal before - after field irrigation system development respectively.
The observed irregular differences between the estimated water consumption values (WU) of the tested crops and the regular differences between the applied irrigation water values (AIW) for the same crops before and after field irrigation system development may ascribed to the possitive effects of the development. One of the most important positive effects of irrigation system development is farmers’ conviction at the head, middle and tail of irrigation canals of equitable water distribution.
Effects of field irrigation system development on water saving
Data indicated that the increments in water saving were associated with the increases in the quantity of applied irrigation water for each irrigation during growth season. The heighest values of water saving were observed at the sowing irrigations for each crops.
A substantial increases in water saving for all the tested crops irrigated from Arafa mousa at the head, Elafeer2 at the middle and Elbanna meaqa’s at the tail of Nekla canal as affected by field irrigation system development. The average increases in water saving were about 10.8, 11.2 and 10.6 % for crops irrigated from the three tested meqas respectively.
The average increases in water saving for wheat, rice, Egyptian clover, cantaloupe and watermelon pulp as affected by field irrigation system development were about 7.36, 12.9, 13.7, 10.6 and 9.88% respectively.
Effects of field irrigation system development on crop yield and water productivity
Concerning crop yield as affected by field irrigation system development, results indicated a slight increases in yield of the tested crops either irrigated from head - Arfa Mouse, middle - Elafeer2 or tail, Elbanna mesqas. The average increases were about 6.98, 5.99 and 7.19% respectively.
The average relative increases in crop yield of wheat, rice, Egyptian clover, cantaloupe and watermelon pulp as affected by field irrigation system development were about 6.84, 5.83, 6.11, 6.01 and 6.68% respectively.
Data showed that the expected improvment in water distribution equity after field irrigation system development was more effective in increasing crop yield irrigated from the tail of Nekla canal (Elbanna mesqa). This increase in crop yield was more pronounced for wheat, Egyptian clover and watermelon pulp.
Data revealed a substaintial increases in crop water productivity for all the tested crops irrigated from Arafa Mousa at the head, Elafeer2 at the middle and Elbanna meaqa’s at the tail of Nekla canal as affected by field irrigation system development. The average increases in crop water productivity were about 19.9, 19.5 and 20.0 % for crops irrigated from the three Meqas respectively.
The average increases in crop water productivity for wheat, rice, Egyptian clover, cantaloupe and watermelon pulp as affected by field irrigation system development were about 15.3, 21.5, 22.9, 18.5 and 20.6% respectively.
The increases in crop yield and crop water productivity may be due to the positive effects of field irrigation system development on regular availability of water in the irrigation canals and the ease of the application by the farmers with more accuracy and with less effort, which ultimately lead to improve rationalize the use of water resources.
Effects of irrigation system development.on water balance
Results revealed that the net water balance (NWB) values decreased to about 87.6, 76.7 and 85.5% as affected by field irrigation system development relatve to values before development equal to 100 for wheat, rice and Egyptian clover respectively under irrigation from Arfa Mousa mesqa at the head of Nekla canal. Similar results were also observed for wheat, rice and Egyptian clover irrigated from Elafeer2 at middle, and Elbanna mesqa at tail of Nekla canal.
The average total inflow values for crops irrigated from Nekla canal before field irrigation system development were 2691, 6591, 3901, 2465 and 1365 m3/Fad for wheat, rice, Egyptian clover, cantaloupe and watermelon pulp respectively. While the average total inflow values for crops irrigated from Nekla canal after development were 2405, 5741, 3363, 2219 and 1242 m3/Fad for wheat, rice, Egyptian clover, cantaloupe and watermelon pulp respectively.
The average total outflow values for crops irrigated from Nekla canal before field irrigation system development were 2192, 6441, 3440, 2325 and 1245 m3/Fad for wheat, rice, Egyptian clover, cantaloupe and watermelon pulp respectively. While the average total inflow values for crops irrigated from Nekla canal after development were 2031, 5611, 2969, 2079 and 1122 m3/Fad for wheat, rice, Egyptian clover, cantaloupe and watermelon pulp respectively.
Effects of irrigation system development on salt balance
As expected, the results showed that the amount of salts added (SA) to rice-cultivated soil irrigated from Arafa Mousa at the head, Elafeer2 at the middle or Elbanna mesqas at the tail of Nekla canal were higher before development than after field irrigation system development.
While the amount of salts removed from rice-cultivated soil irrigated from Arafa Mousa at the head, Elafeer2 at the middle or Elbanna mesqas at the tail of Nekla canal tail was lower before than after field irrigation system development.
The amount of salts removed (SR) from the cultivated land with wheat, Egyptian clover, cantaloupe and watermelon crops was higher before than after field irrigation system development.
It could be observed that the average amount of salts added into soil cultivated with wheat, rice, Egyptian clover, cantaloupe and watermelon pulp were 800, 2350, 1255, 848 and 454 kg/Fad respectively before and 702, 1939, 1026, 719 and 388 kg/Fad after field irrigation system development.
The average amount of salts removed from soil cultivated with wheat, rice, Egyptian clover, cantaloupe and watermelon pulp were 722, 2456, 1337, 802 and 454 kg/Fad respectively under irrigation from Nekla canal before development and 567, 2887, 591, 598 and 309 kg/Fad after field irrigation system development.
However, the relative net salts outflow or removed from the growth medium of the tested crops were in the descending order: Rice > Egyptian clover > Wheat > Cantaloupe > Watermelon pulp as affected by field irrigation system development.
It could be concluded that field irrigation system development has a positive effect on water saving, crop yield, water productivity and reducing salt accumulation in crop growth medium because field irrigation system development prevent seepage and weed growth increases in the developed mesqas and made water available all the time in the mesqa.