Every farming operation is different, so the things that can increase efficiency the most may also differ for each enterprise. This section will discuss some of the areas where efficiency can be improved. Later sections of this module will look at practical examples of how to achieve this, along with examples of how some growers have put many of the ideas discussed into practice.

Increase the hectares per tank load to reduce number of fills required

Tank size and application volume are the main drivers of hectares per tank load.

Application volume

Reducing application volumes (litres per hectare) will increase the number of hectares per tank, but may also reduce efficacy. For every application, the application volume (L/ha) must be adequate to produce enough coverage of the target for the products being used. Before adjusting the application volume, the operator must take into account the spray quality (droplet size) required and how the product translocates within the target (particularly with herbicides). Often product labels state the minimum spray quality and/or water rates that are permissible to be used to ensure satisfactory results. For many products it may be useful to assess the spray deposits and efficacy achieved in small strips or trials before changing application volumes.

Find out more

For more information on assessing deposition refer to Module 21: Assessing spray deposits

Tank size

Increasing the tank size can enhance productivity by reducing the number of fills required to complete a job. As a simplified example we will compare a 3000-litre tank to a 6000L tank for a spray job to cover 300 hectares with a pre-emergent herbicide at an application volume of 100L/ha.

If we assume a spraying rate of 60ha/hour while in the paddock, this job requires five hours of actual spraying time.

If we assume the turnaround time for mixing and filling for both tank sizes is around 30 minutes, then:

• the 3000L tank at 100L/ha will spray 30ha before refilling and will require nine refills to complete the job = 5 hours spraying time + 4.5 hours of filling (efficiency = 5/9.5 x 100 = 52.6%); and

• the 6000L tank at 100L/ha will spray 60ha before refilling and will require five refills to complete the job = five hours of spraying time + 2.5 hours of filling (efficiency = 5/7.5 x 100 = 66.7%).

Before increasing the tank size, either by purchasing a new sprayer or modifying an existing one, carefully consider factors such as the sprayer pump size and agitation requirements for the tank. Also consider the weight, balance and tyre constraints of the sprayer, achievable and safe transport speeds, stability and possible compaction issues.

Find out more

For more information see Module 15: Weight, balance and tyres

Reduce time travelling to and from mixing sites and fill points

Once the tank size and boom width have been optimised for the enterprise, the greatest increase in overall spraying efficiency will come from having the mixing and filling facilities as close as practical to the area to be sprayed.

Having a portable mixing and transfer set-up, along with a suitable size water cart that can be moved to wherever the sprayer is located, will save transfer time out of the paddock and engine hours on the sprayer.

Taking water and product to the paddock can be done in many different ways.

Large operations may consider a road-train set-up, with something like a drop-deck torque-liner rear trailer with all the product, mixing, batching and safety equipment and spare parts required for the spray job, along with a lead trailer fitted with the water tanker or tanks. The torque liner keeps the products and equipment out of the weather and everything is covered during transport.

Having the water on the lead trailer means that the rear mixing set-up can be disconnected easily so the water can be refilled easily. This type of set-up can also work as a B-double set-up.

If conditions are not suitable for a prime mover, have a ‘bogie dolly’ so the trailer(s) can be moved to the paddock using a tractor.

For medium-sized operations a similar set-up may be fitted onto a single trailer or body truck.

There is no ‘one-size-fits-all’ solution to creating a portable mixing-and-transfer set-up; the idea is to develop something that works for your operation. This could be done in several steps provided that things are carefully planned before you start; to avoid duplication or reduced efficiency.

Where to start?

A useful place to start is with a water cart and portable batching set-up to help improve the mixing and measurement process, particularly for granules and solids.

Ideally, the water cart would hold enough water for the entire day of spraying, but even having enough for two loads will halve the number of trips to the fill point.

Over time, batching plants can be incorporated into an integrated portable set-up, such as a mixing trailer, which can be moved to the spraying site ahead of time.

Some operators also include a rack or hoist for a motorbike, or a hitch for a quad bike, to avoid having to move the mixing and transfer set-up for minor tasks or returning to base. This is particularly useful when one person is operating the system.

Increase the number of fill points around the farm

Even if your average travel speed to and from the fill point is 20 kilometres per hour, a round trip of just 4km would take about 12 minutes per load. Doing this four to five times in a day of spraying, would add up to 45 to 60 minutes out of the paddock. This is the equivalent to spraying one less tankful per day.

Using the sprayer to transport water is an expensive exercise when you consider the impact on engine hours and wear and tear, particularly on tyres and wheel motors for hydrostatically driven self-propelled sprayers.

Where it is not possible or practical to use a large tanker for transporting all the water you require for a job, increasing the number of fill points around the farm will reduce the time taken to access water and return to the paddock to be sprayed. This can

be achieved by either plumbing permanent water outlets or installing several storage tanks and fill points that can be regularly topped up. Tanks have the advantage that they can be pre-treated with water conditioners before spraying activities.

When considering the location of storage tanks and fill points, carefully consider access to each of them in all weather conditions. Also consider the quality of internal roads or tracks and achievable travel speeds, both full and empty – especially the full weight of the sprayer and the tyre capacity, as well as any vehicles that may be used to fill storage tanks when you are not spraying.

When establishing fill points, it also helps to think about the pump requirements to fill each load in a reasonable timeframe. Using the sprayer’s own pump to fill the sprayer may be too slow for large volumes and will unnecessarily increase the engine hours of the sprayer.

For large spray tanks it is a good idea to have an external fill and transfer system to increase the speed and accuracy of the filling operation.

Eliminate folding and unfolding

The ability to mix and fill the sprayer close to the paddock, preferably at the end of a paddock, eliminates the need to fold and unfold the boom until you have finished spraying that paddock.

On average it takes about six minutes to fold and unfold most large booms, by the time you ensure it is level and the height is correct. If this is done four to five times in a day of spraying, it would result in 25 to 30 minutes of lost spraying time per day, which, over several days of spraying, would add up to several loads that could have otherwise been completed.

Eliminating folding and unfolding in the paddock can only be achieved by having portable mixing equipment and a water cart, or alternatively ‘batching’ an entire load in an equivalent-sized tank close to each sprayed paddock. It will be important to consider where the fill point is located on the sprayer: having them mounted at the front of the sprayer can make it simple to approach and exit the mixing and filling equipment.

Examples of productivity gains through changes to equipment or practices

By increasing tank size, eliminating folding, and reducing turnaround times, the hectares sprayed can be substantially increased.

Potential lost productivity will occur as a result of tank size and fill rate, folding and unfolding of the boom, complexity of the mixing operation and travel to and from mixing points relative to mixing at the application site. Each operation will have different numbers, so it is important to do your own calculations to understand what changes can be made to improve efficiency.

Table 1 shows that there is a large increase in efficiency when moving from a 3000L to a 6000L tank, and a further, but smaller, increase in productivity in going from 6000L to 9000L tank size.

This example also highlights that it is realistic to expect somewhere between 10 and >25% increase in operational efficiency by moving the mixing operation to the paddock edge. Total savings will depend on the tank size, travel distance to refill and spray application parameters. (These projected saving are without any changes to sprayer width or application speed).

Improve the efficiency of mixing and transfer operations

Use mixing vats for solid products

The results of poor mixing, particularly of solid products, can be seen by the operator as blocked filter screens, residues in the bottom of the batching or main spray tank or at the end of boom lines. It is important to fill the spray tank as quickly as possible, but not so quickly that the mixing process and products could be compromised.

Using a mixing vat with a cone-shaped bottom to pre-dissolve solid products and to ensure they are fully dispersed in the water before they are transferred to the main spray tank can eliminate many problems. Having water already in the main tank and the agitation running, will help to disperse the product as it is transferred from the vat.

Tip

Have a tank fitting in the side of the mixing vat and an anti-vortex fitting in the vat outlet. Arrange the plumbing so liquid can be sucked from the side of the vat and returned to the vat from the bottom. This can greatly assist with dissolving solid products quickly.

Pre-treat poor quality water where required.

It takes time to fully dissolve products such as crystalline ammonium sulfate (CAMS), especially if the water temperature is low e.g. during winter. Spray operators should allow at least 10 minutes to fully dissolve the CAMS before adding other products.

Waiting for products such as CAMS to fully dissolve while you are mixing a load in the middle of a spray job can seem to waste valuable time, but if it is not done properly the tank mix may be compromised.

There are two general approaches to reducing mixing times when using CAMS, one is to pre-treat the entire water volume required for a load or the day by batch mixing, the other is to pre-dissolve a known quantity per litre, and to use the pre-dissolved liquid in place of the crystalline solid.

Where large volumes of water are required for a particular spray job, consider treating enough water for several loads in a batching tank before you start the spraying operation.

If pre-dissolving the CAMS, carefully identify the solubility of the product; this information can be found on the Safety Data Sheet (SDS). Different CAMS products may specify different solubility rates (grams per litre that can be dissolved). Many crystalline products can be dissolved at 500 grams per litre (g/L), which would allow the operator to use 2 litres of the pre-dissolved product in place of 1 kilogram of the crystalline form.

Always check the solubility of any solid product you intend to use.

Improve transfer systems

Reducing the fill time will not increase productivity if it results in a poorly mixed load that affects the overall efficacy of the job. While the rate at which we can transfer water to fill the main tank reduces time out of the paddock, using the same system to ‘suck’ chemicals from ‘shuttles’ or ‘envirodrums’ may not be appropriate for measuring or transferring smaller volumes.

Transfer pump alternatives

There are many approaches to the mixing and transfer pump set-up, but generally there are two common set-ups growers have used to improve efficiency.

The first option is to have a single 3-inch / 75mm poly pump for transferring water only, and a 2-inch / 50mm pump for transferring products and the contents of the vat. While the 3-inch pump can fill the sprayer quickly, it is generally too fast for sucking product directly from shuttles or envirodrums.

For many operations it is useful to match the pumps so that parts and fittings are identical, such as having two separate 2-inch poly pumps. One of the 2-inch pumps for water only, and the other 2-inch pump for operating the mixing vat, water flushes, sucking product from the shuttle and/or envirodrum directly to the mixing vat, batching tank or the main spray tank.

Where the pump set-ups are identical (e.g. both 2-inch), it is useful to spray-paint the clean water fittings all one colour (e.g. blue) and to have different coloured hoses for the clean water system and the product transfer system.

Closed measurement and transfer systems for liquids

The best way to reduce risk to the operator and increase efficiency is to use a closed transfer system to measure how much product to add to a vat or tank, which avoids the need to pour or decant from drums or shuttles.

Chemical flow meters and chemical transfer pumps can increase the accuracy of the measurement, but some are also quite slow. Direct measurement from shuttles needs careful consideration.

Tips

• It is important to maintain hygiene at all times: install dust caps or plugs as soon as the camlock is disconnected from fittings (e.g. mount plug on the side of the chemical transfer system). As soon as the hose is disconnected from the sprayer it can be connected to the dust cap.

• When using camlocks, it is ideal to install the male then female camlock in the direction of flow e.g. CFS plumbing.

• Before installing or using male camlocks, level the face of the camlock until all of the dull or higher points have been removed. You may choose to use wet and dry sandpaper to improve surface.

• You can purchase shims to place under the gasket in the female camlock to help improve sealing.

• Face mounted camlocks downwards at 45° or 90°, not horizontal, this will reduce the pressure/weight of the hose on the seal.

• Triple-rinse shuttles by installing a tank-rinse fitting in a spare lid. When required, the operator can swap lids and connect to fresh water to triple-rinse the shuttle.

• Having shuttles and/or an envirodrum connected to a common suction hose can potentially create product cross-mixing and decontamination issues. A good option is to have a shuttle camlock manifold with one- way valve and manual ball valve manifold so air can enter suction hose and remove most of the product from the line. Close the air manual ball valve and open the manual ball valve on the manifold with one- way valve from water source and flush all the residual product out of the suction line. Obviously, if using products that could affect the next crop, a more through clean would be required.

Measurements of product

How accurately you measure products for each load may impact on the outcome of the spray job. The more highly loaded the product is – and the lower the rate of product per hectare is – the greater the need for accuracy.

For products such as water conditioners, the accuracy may only need to be in kilograms per tank load or in bags per tank if the bag weight has been checked.

For some liquid products, or powders where the rate is in millilitres or grams per hectare, accuracy becomes much more critical. Using accurate scales or chemical transfer meters that have been calibrated for the specific product density can improve accuracy.

Where a chemical transfer meter is not suitable for the container type, and larger volumes need to be transferred, you must check the accuracy of anything you use to measure the product with.

Transferring from shuttles and vessels using hoses

Measurements should allow for the volume of product that will be held in the hose itself, particularly when transferring product directly into the spray tank from a shuttle. This is particularly important if the product is not immediately being flushed from the line by clean water. However, these hoses should still be flushed with clean water into the spray tank for last load for the day / spray job, with adjustments made for the chemical calculations.

It is also important to consider the volume held within the hose when transferring small amounts of mixed products from vats and mixing vessels.

Liquid height in the shuttle

It is recommended that spray operators do not rely on the accuracy of the graduations on a shuttle for measurement of product. However, it may be useful to double-check volumes transferred against the shuttle levels using an accurate ruler.

In theory, for a 1000L shuttle, you could measure the height of the liquid when full, then work out what volume is delivered per centimetre drop in this level. Once this has been established, the reduction in liquid height may be used as a guide to the volume of product that has been transferred from the shuttle.

Using a ruler can assist with estimating how much product has been used or still remains in the shuttle.

If the shuttle shape changes over its height, or wall thickness varies, this method will lose accuracy.

Measuring output against changes in the height of volume in the shuttle should only be used when more than 50L of product needs to be transferred to a vat or tank. For smaller volumes, the accuracy must be checked in an accurate measuring vessel.

Suspension concentrate (SC) formulations

SC formulations are typically a dry formulation which has been ground to a small particle size and suspended in water by use of a combination of suspension agents. 

Making the formulation 'viscous' will reduce the degree of settling of the active ingredient over time, but this can make the formulation difficult to pump (especially when cold). Conversely, reducing the viscosity to make the formulation easier to pump substantially increases the risk of the active ingredient settling to the bottom of the container when in storage.

If drums have been stored for some time then they require shaking or rolling to redistribute the active ingredient throughout the formulation. Obviously this is not practical with shuttles. Without some form of vigorous shaking there is the risk that the concentration of active ingredient is lower at the top and higher at the bottom of the container.

It is best to always use SC formulations in the season of purchase.

Where possible, source SC formulations in a pack size that will result in the whole contents of a single pack going into the sprayer at once. This will avoid the need for shaking.

For example: a 6000L spray tank applying at 75L/ha will treat 80ha. If the product use rate is 2L/ha then 2 x 20L drums will be an idea pack size.

Direct injection (advantages and limitations)

Direct-injection systems eliminate the need for measuring and mixing for most liquid products and have the capacity to more accurately deliver the required rate than a conventionally mixed tank, where variation in concentration throughout the load can occur due to the tank shape or the capacity of the agitation system.

Direct injection allows the operator to use a fully closed system, which means that the time and potential risks normally associated with mixing operations are eliminated for products that are available in containers such as ‘envirodrums’ where ‘micromatic’ fittings are used.

Direct injection also allows the spray operator to stop at any time without having to worry about potential interactions in the tank, as it usually holds clean water, or water and an adjuvant or water conditioner. When spraying has to stop, the spray lines can easily be flushed with clean water, and only the parts of the system where product has actually contacted need to be decontaminated.

Direct injection also opens up the opportunity for variable-rate application, without changing the total application volume.

However, direct injection does present a challenge for dry products and suspension concentrates. Generally, dry products need to be mixed in the tank, as with a conventional sprayer set-up. There are options to pre-dilute and inject suspension concentrates and flowable formulations, although they will add additional expense and require additional room on the sprayer to mount.

Direct injection may not be immediately compatible with some recirculating booms, unless the recirculation system can be turned off when direct injection is used.