الفهرس 
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Abstract
This study was carried out to evaluate the technical and
economical characteristics of four types of chemical applicators
(Knapsack hand operator sprayer,knapsack air-carrier
sprayer, stationary field sprayer, and mounted-boom field
sprayer) .
All sprayers under study were tested and evaluated by
making comparison between them to study the following points:
1- Field efficiency.
2- Actual productivity.
3- Covering efficiencies.
4- Operation costs.
5- Economical advantages criterion.
The important results obtained from this study can be
summarized as follows
1- Field efficiency :
It was found that the stationary field sprayer {S3} gave
the highest field efficiency {60%}, comparing with the three
systems of sprayers {knapsack hand sprayer, knapsack aircarrier,
and mounted-boom field sprayer} {42, 41 and 16%} .
The differences between them are due to the time losses of
spraying.
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2- Actual productivity :
from the results, the mounted-boom field sprayer gave
(5.92 ha/h) actual productivity comparing with the others
systems (knapsack hand sprayer, knapsack air-carrier, -and
stationary field sprayer) (0.49, 0.68 and 1.31 ha/h) , this is
due to the differences between them in forward speeds, and
width of sprayers.
3- Covering efficiency
The systems under study differed in covering efficiency
due to the differences between their natures of the method of
spray application. It was found that the knapsack air-carrier .
sprayer gave the best covering efficiency (78%) comparing
with the others systems (knapsack hand sprayer, stationary
field sprayer, and mounted-boom field sprayer) which gave
18%, 53% and 21% resp.
4- Operation costs :
The highest cost/h per one operating hour (17.L.•E/h) was
recorded by mounted-boom field sprayer, mean while the same
system gave the lowest operation cost/ha (2.93 L.E/ha), comparing
with the knapsack hand-sprayer, knapsack air-carrier,
and stationary field sprayer, which gave (2.065, 6.285 and
8.33 L.E/h and 4.21, 9.25 and 6.30 L.E/ha resp. These results
are due to the increasing in actual productivity for system
mounted-boom field-sprayer decreasing operation cost per ha.
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5- Spray modeling program :
from this study computer program can be made for spraying
machine to select the optimum spraying machine under different
operation condition via input required data in the
program.
6- Economical advantage criterion :
The knapsack air-carrier gave the highest economical
advantage criterion (1357.72 L.E/ha) comparing with systems
of knapsack hand sprayer, stationary field sprayer, and
mounted-boom field sprayer, which gave (302.85, 922.18 and
357.98 L.E/ha) resp. The knapsack air-carrier recorded the
highest economical advantage criterion L.E/ha, although it
gave the highest seasonal cost (46.25 L.E/ha), but with the
best covering efficiency (78%), which caused an increase in
the final yield of cotton.
New contribution in this research
A computer program was devised to compare between different
spraying machinery in different situations. The’program
has 3 main subroutines: (1) productivity factors, (2) operatiGn
cost factors, and (3) an economical-advantage criterion which
combines the effects of cost and yield variations due to
spraying, to guide selection of optimum spraying machinery
for different situations.
RECOMMENDAT:IONS
from this research the following can be recommended
- The use of the knapsack air-carrier sprayer in cotton pest
control. This is due tQ high covering efficiency resu+ting
from its application.
- Development of this sprayer for greater swath width, and
for local manufacturing.
- Availing this type of sprayer for use in mechanization
centers.
- Carrying on with more research on nozzle boom for mounted
sprayers, and investigating the possibility of using air
jets to aid in spray coverage. Care also should be given to
perform other field operations in a way to allow proper
pest control mechanization (starting from soil preparation
and ending with harvesting) .