الفهرس 
Irrigation managementOnly 14 pages are availabe for public view
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Abstract
Ahmed El Sayed Fahmy Mohamed: Optimizing of Nitrogen Fertilization
under Drip Irrigation System in Sandy Soil Using Nuclear Techniques.
Unpublished Ph.D. Dissertation, Department of Agricultural
Engineering, Faculty of Agriculture, Ain Shams University, 2016.
Sand soil is characterized as poor fertile and no structured one therefore
irrigation water may lose rapidly from the soil profile. Cultivation of such
soils needs more attention to be paid for water and nutrient, especially
nitrogen, management. In this regard, nitrogen management should provide
an adequate supply for a crop throughout the growing season. If the amount
of nitrogen is limiting at any time, there is a potential for loss in production.
This work aimed to improve nitrogen efficiency as affected by irrigation
water regime, N forms and rates (splitted doses). Therefore, a field
experiment on sandy soil was conducted to trace the beneficial effects of urea
and ammonium sulfate fertilizers added at different rates on pea growth and
nutritional values as interacted with different water regimes. 15Nisotope
dilution technique was followed to distinguish between the different N
proportions derived to pea plants and in the same time estimating the efficient
use of both two nitrogen forms (%NUE). Water regime and fertilization
treatments were applied under surface drip irrigation system. Two water
regimes represented 100% and 75% of water requirement in combination
with three N fertilizer rates, i.e. N0, N100 and N75 were applied.
The overall means of seed yield as affected by nitrogen fertilization
treatments represent relative increase accounted for 45.8%, 38.7%, 41.7%
and 36.2% over the unfertilized control for Urea100, Urea75, Ammonium
Sulfate100 and Ammonium Sulfate75, respectively. It seems that 100% water
regime (W1) made nitrogen fertilizer, especially with high rate, more
available for plant uptake comparing to the low water quantity regime. Pea
crop had accumulated more nitrogen from urea comparing to ammonium
sulfate fertilizer. Nitrogen uptake, in general, significantly correlated to
application rate.W1water regime in combination with ammonium sulfate
fertilizer resulted in the best percentage or absolute values of N derived from
fertilizer by pea seeds. It was clear that efficient use of ammonium sulfate, to
some extent, doesn’t affected by different water regimes. This holds true
either at 100% or 75% application rates. On the other hand, urea added at rate
of 75% was more efficiently used by seeds than those added at rate of 100%
of the recommended rate.
Application of 75% of Etc (W2) treatment gave a remarkable yield and
pronounced water saving therefore it is technically and economically
recommended. For instant, the overall mean of water regime indicated that
seed yield (2184.4 kg ha-1) achieved by W1 (100%) was nearly closed to
those obtained with W2 (75%) (2167.4 kg ha-1).
Key words:
15
N, Irrigation Regimes, Nitrogen Fertilizer Form, Pea and
Water use efficiency.
ACKNOWLED.