Friday, 3 June 2011

Spraying 101

It is almost that time of the year, when the farmers are out in the fields spraying their crops to help protect against weeds and insects. I have complied a few tips regarding nozzle selections and spraying techniques that you may find useful.

Nozzle Selection
Standard flat fan nozzles are measured at 280 kPa. Lower pressures will decrease the fan angle and can affect distribution across the boom.
Generally, 110° is used, so that there is a double overlap of spray patterns at lower boom heights.

Nozzle Size
The total volume of spray mixture to be applied. (Ha)
The operating speed of the boom sprayer. (km/h)
The nozzle spacing of the boom (cm)
Individual nozzle output (L/min)=
Boom output(L/ha) x Speed of the sprayer(km/h)xNozzlespacing (cm)

Types of Nozzles
Standard Flat Fan Nozzle (200-300 kPa)
Low Pressure (LP) Flat Fan Nozzle (70-100 kPa)
Extended Range (XR) Flat Fan Nozzle- applies constant spray over  varying pressures.
Boom Stability
Both vertical and horizontal movement of the boom will affect sprayer distribution.
Before selecting a boom sprayer, test it under the conditions it will be performing in.
Nozzle Alignment
To avoid clashing of nozzles leading to uneven distribution of product, offset nozzles 10-15° to the spray boom. 
Self aligning nozzles are available. They have a self locking mechanism that is preset to work with the boom. 
Ground Speed  
All depends on individual needs. 
Top speed 15-20 km/h

Marking Systems
  Can vary from:
Disc or mechanical markers,
Foam, paint or dye markers,
Seeding equipment marks, sight marks, or tramlines.
Paint will not harm crops. 
  Essential to ensure there is proper distribution.
Filling the tank: 80-100 mesh filter
In-line filter-suction line to pump: 80-100 mesh filter.
In-line filter-outlet side pump: 100-120 mesh filter
Nozzle filter: usually 80-100 (depending on nozzle size)  

Boom Height (Height fo the nozzle above the target)

The fan angle of the nozzle and nozzle spacing at the boom will determine boom height.
Nozzle spacing of 50 cm:
80° nozzle fan, 60 cm above target, for double coverage.
80° nozzle fan, 45 cm above target for 1.5 times coverage.
110° nozzle fan,  35 cm above target for double coverage.
110° nozzle fan, 26 cm above target for 1.5 times coverage. 
 I hope you all have found these tips useful, and happy spraying :)

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