Agriculture Reference
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plants with shallow root system even using brackish irrigation water if the crop salin-
ity tolerance is considered.
Water balance calculations revealed that minimum drainage occurred during the
20 cm IPED scenarios. Using short IPED with or without brackish irrigation water
in APRI thus can reduce groundwater contamination risk. It was noted also that the
defi cit in applied irrigation water was compensated by soil water contribution. The an-
tecedent water content value plays a major role in controlling root water uptake rates.
9.5 SUMMARY
Modern irrigation techniques are becoming increasingly important in water-scarce
countries. In this study, a two-dimensional water and solute transport model, HY-
DRUS-2D, was used to assess the impact of interplant emitter distance (IPED) and
irrigation water salinity on soil moisture and salinity distribution as well as on water
balance components under alternate partial root-zone surface drip irrigation (APRDI)
of tomato growing in loamy sand soil. Three IPED (20, 30, and 40 cm) and three ir-
rigation water salinity levels (0, 1, and 2 dS/m) were used to execute different simu-
lation scenarios. Simulation results indicated that the fluctuations in water content
within the root zone were more pronounced in case of 20 cm IPED. The root water
uptake increased as the IPED decreased. Using brackish irrigation water in APRDI
caused significant augmentation in soil salinity in the top soil layer especially at the
location of plant. The impact of irrigation water salinity on root water uptake increased
as the IPED increased. As irrigation water salinity increased the root water uptake de-
creased. At plant location, soil salinity reached its highest values at the top soil layer in
case of 30 and 40 cm IPED with brackish irrigation water. However, high soil salinity
values were observed between the 40 and 65 cm depths in case of 20 cm IPED. Based
on the results, it appears that APRDI with nonsaline irrigation water is more effective
with short IPED considering that approximately half of the root system was exposed
to drying cycle. In addition, short IPED is recommended in APRDI when using brack-
ish irrigation water especially for plants with shallow root system taking into account
crop salinity tolerance.
KEYWORDS
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abscisic acid
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Alternate partial root-zone surface drip irrigation
•
Alternate partial root-zone irrigation
•
Brackish irrigation water
•
Brackish water
•
Conventional deficit irrigation
•
Egypt
•
El-Salam Canal, Egypt
•
Hydraulic conductivity
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