Crop Sprayer Developments and Technology

The guest speaker at a recent technical meeting of the Northern Ireland Branch of IAgrE was Mr Kerry Day from Spraysure Ltd.  He started this company 20 years ago following his career experience with GEM Sprayers, CASE IH and Househam Sprayers. His company now provides comprehensive specialist support including calibration, parts, NSTS testing, hydrostatic drive servicing and a seven day breakdown repair service to its customers across England and Northern Ireland. It has branches at both Lincoln and Downpatrick, Co.Down.  Spraysure Ltd are also sales and service agents for FarmGEM Sprayers, TeeJet Technologies, Poclain Hydraulics and other product brands.

Effective and safe crop spraying requires well maintained equipment with the correct nozzle types and working pressures for the specific crops in local conditions.  The presentation included the following subject areas.

Advancing nozzle technology
In very calm conditions, fine droplets can provide acceptable crop spray cover but in our typical wind and weather conditions unacceptable spray drift is likely. Hence expert advice on the choice and use of the correct type of nozzle at its recommended operating pressure is vital. Most users are familiar with the traditional flat-fan or hollow-cone pattern nozzle types and chart information is available to describe their flow rates / size of droplets across the range of working pressures. Individual  nozzles are usually spaced at 50cm across the spray boom. The option of multi-turret nozzle bodies now assists rapid manual changeover for different conditions. Various systems are now also available with a different jet angle and direction. For example, in some cereal crops, better spray cover can be achieved by using both a forward downward angled jet and a following rearward jet, This can be achieved from 2 nozzles carried in a special holder or from separate jets in a single nozzle. For some crop conditions, alternate forward and rear facing angled nozzles are recommended.  

A significant recent, but already popular, development is the air stream nozzle. It produces larger droplets, containing small air bubbles. which are less prone to drift.  They stay in contact with the leaf for longer than the usual large and heavier droplets which are more likely to roll off.  Liquid from the boom enters each nozzle body via a tapered channel where  the stream speeds up creating  a vacuum (the Venturi effect) to draw air in via side vents. The air and liquid then mix in the mixing chamber before passing out through the nozzle tip as air-filled droplets.The actual performance of low drift nozzles is now officially assessed with regard to their safe use adjacent to designated vulnerable environmental areas. Those approved, after official testing, are awarded a star rated LERAP ( Local Environmental Risk Assessment) rating. Other spray nozzle quality assessments also exist such as the JKI rating from Germany.

Booms with closer nozzle spacing (such as 25cm or 33cm) are also now  available and reduce the risk of drift by being carried closer to the crop.

Rate adjustment systems
Where ground speed monitoring is available, an automatic flow rate adjustment system can maintain an even application rate if the tractor’s travel speed changes.

Electronic switching on / off, through control linked to the ISOBUS system on recent tractors, gives the option of variable rate application in response to GPS field maps.

When travelling around a curve the boom section on the outside moves faster over the ground than the inside.  Electrically controlled pulse nozzles are now available which rapidly switch on / off (at around 60 cycles / second) and their application rates depend on the proportion of “on” time. On a flow-control type sprayer the pulse width modulation  (PWM) system controls the output of individual nozzles across the boom to maintain overall even coverage. Although this system is currently used in the US and Australian markets it is still not common place in the UK and Ireland.

Liquid fertiliser
Interest in spray application of liquid fertiliser has increased. Special nozzles are now available to cope with the higher specific gravity (density) of the liquid and higher flow rates used compared to the usual water based crop protection products. They produce several liquid streams (4 to 7 depending on the manufacturer) of large droplets directing the liquid towards the soil root zone rather than the crop leaves.  For application of foliar feed products more traditional nozzle designs may be used but users should always check in advance , with their nozzle suppliers, if this is appropriate,

Handling crop protection concentrate containers
For most crop sprayer filling operations the operator opens the product container manually and pours in the appropriate amount to a low-fill induction hopper. Mr Day described a closed transfer system where the product container is inverted, with its cap still secured, onto a compact coupler device mounted on the sprayer. The Pentair Hypro Cleanload Nexus accepts a specially designed Easy Connect 63mm cap, with its own internal valves, as now available on containers of up to 20 litres.  Manual operation of the external control  can release all or part of the contents into the sealed system and carry out a final triple rinse of the container. An inbuilt accurate measuring device for smaller quantities is being developed. The system protects the operator from direct contact with the concentrate and the caps can be reused. Main crop protection product manufacturers in Europe are very supportive and it is likely that the system of using Easy Connect caps could become a standard accepted practice in the industry.

Sprayer testing
The NSTS (National Sprayer Testing Scheme) now requires most boom sprayers to be officially tested every 3 years. Spraysure Ltd is one of the officially certified centres offering this service. This includes close examination of all aspects of the machine’s physical, hydraulic, pneumatic and electrical functions as well as checks of nozzle outputs and working travel speed. Operators are advised to check nozzle condition and outputs at least annually as nozzle tips can wear resulting in an uneven or excess application rate. Ideally they should carry out a regular calibration check especially if changing to work with a different product or crop. The technical information available from a specialist supplier can be key to keeping all of this in order. Nozzle charts are provided to assist you in  choosing the best nozzle tip for the job. A modern option is using an App, such as TeeJet’s “SpraySelect”. When you enter the speed, application rate, nozzle spacing and preferred droplet size it will list its recommended nozzle tips for the job.

Discussion period
A discussion period, based around the topics which had been referred to in the presentation, then followed before Branch Chairman Ken Gardiner  concluded the meeting by thanking Mr Day for his most interesting and informative presentation. He wished him and his company every success in continuing to provide this important service for the agriculture industry.

More detail of the wide range of Spraysure Ltd services can be viewed on www.spraysure.com and www.sprayerpartspecialist.co.uk