الفهرس 
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Abstract
The aim of this work was studding the possibility of using surface and subsurface drip irrigation systems in sandy soil with some soil conditioners for improving onion yield, irrigation efficiency, choice the better irrigation interval to improving onion growth and overcome salt problems.
This work was conducted on sandy soil at a privet farm (Badr El Hedaya Society Center in El Bohera Governorate) during 2004 and 2005 seasons. The experiment consists of eight treatments and treatment two control in three replicates (thirty experimental units), the water irrigation level (100 % and 80 % of irrigation water applied according to Omary et al. (1995) and soil conditioners (gravel and sponge)
The treatments under study were:
T1 (control)- Surface drip irrigation system (SDIS) with 100 % of crop water requirement and irrigation interval daily.
T2 Subsurface drip irrigation system (SSDIS) with 80 % of crop water requirement and irrigation interval daily using sponge as a conditioners around drippers.
T3 SSDIS with 80 % of crop water requirement and irrigation interval daily using stone as a conditioners around drippers.
T4 SSDIS with 80 % of crop water requirement and irrigation daily using stone and sponge as a conditioners around drippers .
T5 SSDIS with 80 % of crop water requirement and irrigation interval daily without any conditioners around drippers.
T6 (control)- SDIS with 100 % of crop water requirement and irrigation interval every three days.
T7 SSDIS with 80 % of crop water requirement and irrigation interval every three days using sponge as a conditioners around drippers.
T8 SSDIS with 80 % of crop water requirement and irrigation interval every three days using stone as a conditioners around drippers.
T9 SSDIS with 80 % of crop water requirement and irrigation interval every three days using stone and sponge as a conditioners around drippers.
T10 SSDIS with 80 % of crop water requirement and irrigation interval every three days without any conditioners around drippers.
Onion was planted at the first of January (2004) for the first season and replanted at the same time for the second season. The plantation was on two rows ridge (60- cm width) the distance between rows 20-cm and 8-cm distance between plants on two side. In this work different measurements had been done such as; Amount of irrigation water, Water Use Efficiency (WUE), Soil moisture distribution, Salt content distribution and Plant measurements (Different plant samples were collected during growth season to determine the soluble solids (TSS), diameters of bulb, weight of bulb At harvest crop yield was calculated.
Output of this study was
1- The highest yield was T(5) [SSDIS with 80 % of onion irrigation requirement with irrigation interval one day (daily) (without stone and sponge addition) with 10.327 ton/fed. The second treatment T(2) and The third treatment T(10) with 10.173 ton/fed.
2- Water Use Efficiency (WUE) for the ten treatments ( daily and three days intervals) was the best for T(5) with (6.546 kg onion/m3 applied water)and the lower was T(1) with (2.732 )kg onion/m3 applied water
3- Soil moisture distribution after irrigation was studied around onion plant within 10 cm distance (horizontal distance) and vertical distance to 15 cm depth. T (1) shows that the soil moisture content values did not decrease 30 %AW and increased to 95 % AW. T(2) ranged from 38 to 78 % AW , T(3) ranged from 48 to 84 %AW and was better tan T(2). As for T (4) ranged from zero to 90 % AW and T(5) ranged from 30 to 56 % Aw. Using stone and sponge addition with 80% Aw is better than T (2 and 3) for stone and sponge alone, but T (1) was better than all treatments or daily irrigation T(2), T(3), T(4) and T(5).
a. Treatments of after three days irrigation the soil moisture behaved according to the following series: T(9)> T(10) > T(7) =T(6) > T(8), where the soil moisture values were 88, 85, 75=75, and 51% from available water, respectively.
b. Sponge and stone additions gave improving in residual soil moisture values or daily irrigation. As for treatments of three days irrigation, the residual soil moisture values were lower than 50% AW.
4- Salt Concentration in Root Zone was used to study the effect of irrigation intervals for the different treatments. EC of T (9) the highest one and T(8) is lowest one for three days irrigation using SSDIS and T(4) is also highest one and T(3) is the lowest one for daily irrigation using SSDIS. It is notice that EC of the five treatments irrigated each three days are higher than the other five treatments for daily irrigation.
5- 5-Total Soluble Solids (TSS): TSS is the indicator for onion quality, increasing of TSS indicates high quality and vice versa. T(1) is the highest treatment and the lowest one is T(5) under daily irrigation, whenever under three days irrigation T (7) is the highest and T(10) is the lowest, except T(9) was abnormal.
6- Generally, there is no any significant difference between the ten treatments.
7- Weight bulb: bulb weight under daily irrigation is bigger than under three days irrigation. The best treatments are T(3) , T(4) and T(5) under daily irrigation and the lowest treatments are (6) and T(7) under the three days irrigation.
8- Diameter of bulb: T(3), T(4) and T(5) represented the biggest diameters, whenever, T(1) and T(2) were the smallest diameters for the daily irrigation. As for diameters of bulb for irrigation at each three days had behavior the following series: T(10) > T(9)> T(8)> T(7)>T(6). The soil moisture stress, which resulted from the irrigation each three days, had been effect on volume of onion bulb.