To establish what the ideal size of the sprayer should be, and the capabilities it must have, the operator should determine what the total area to be sprayed is and the timeframes that are typically available to complete each spraying operation. This should provide an indication of how many hectares per hour the sprayer needs to be able to cover to complete spray jobs in a timely manner.

Spraying is changing on the farm. Often farm size is getting larger and labour to mix, fill and operate the sprayer is getting scarcer. This is leading operators to choose machines that can treat more hectares per hour. There is also more attention being placed on application under correct environmental conditions, which in many cases may reduce the spraying hours per week. Weed resistance is becoming more common, resulting in more spray passes being required and often double or triple knock programs being needed, targeted at very small weeds.

To understand your spraying capacity needs, consider the following

1. How long should it take to complete the whole herbicide spraying program? Ideally this would be approximately 7-10 days from commencement of the program, before weeds get too large or start to go into environmental stress

2. Do the weeds require a ‘double knock’ for effective weed control? If yes, then realistically the complete sprayed area needs to be able to be treated twice in approximately 14 days.

3. Taking into account local environmental conditions (prevailing wind speed, risk of surface temperature inversions), labour resources and other farm and non-farm activities, how many hours per week is realistically available to be spraying?

For example, if a particular location has around 30 hours per week of suitable spraying conditions (on average over summer) and  the weeds are regularly requiring  the applicator to implement double knock programs, then  the spray equipment needs to have enough capacity to be able to treat the whole spray program/area within that 30 hour window, and then be able to back that up again the following week to apply the double knock. Without this spray capacity being available, either the spray program gets delayed, and weeds get larger and more stressed leading to poor results, or applications are applied under sub-optimal conditions.

The greatest increases in the productivity of the sprayer will come from having a larger tank and operating with a wider boom. While increasing spraying speed can also increase productivity this should be considered carefully as higher spraying speeds will increase the risk of off-target movement of products, result in more interception from stubble which will often reduce the volume of product deposited on the target and potentially reduce efficacy.

Improving the mixing and transfer process can also provide a major increase in productivity, which may help to extend the life of your current sprayer by reducing the overall engine hours.

Find out more

For more information:

• Module 4: drift-management strategies

• Module 9: mixing, filling and transfer systems

• Module 11: pumps, plumbing and components

Integration of the sprayer with other equipment

Tyre centres and machinery widths will only increase efficiency to the level that the accuracy of the GPS and auto-steer functions will permit. The accuracy and repeatability of the GPS is critical to provide the opportunity for additional spraying techniques to be used, such as banded applications and inter-row shielded spraying.

Where the GPS accuracy is 3 to 4 centimetres (or less), matching the tyre centres of all farm equipment will allow for improved row configurations, and may provide the ability to match the nozzle spacing to the crop row width for many enterprises.

It is also important to consider whether several of the sprayer’s functions can be integrated into one central screen for ease of access to various functions, as well as what can physically be displayed while the machine is being operated.

Find out more

For more information:

• Module 12: GPS systems

• Module 15: weight, balance and tyres

• Module 22: integration of the sprayer with other farm equipment