Agrifac shunned the Agritechnica show last year, choosing instead to introduce its latest Condor Endurance II alongside a wide range of high-tech controls at the opening of its new factory at Steenwijk, in The Netherlands.
Booms up to 80m wide can be tested in the new 14,000m² factory, which Agrifac has constructed on its existing site at Steenwijk in the Netherlands.
Agrifac has seen quite remarkable growth in recent years, no doubt the result of investment from its owner – the sprayer specialist group, Exel Industries – which bought the struggling manufacturer in 2012.
Since then, sales of self-propelled sprayers have rocketed – from 20/year in 2008 to more than 200 today. The new factory is currently building a machine a day and Agrifac is now looking to boost sales further by expanding operations in Australia, North America as well as central and eastern Europe.
Sales of Agrifac self-propelled sprayers have risen from 20/year in 2008 to more than 200 today. Its new factory has the capacity to build one machine every day.
Indeed the impressive new, architect designed factory is set-up to test booms up to 80m (~262 ft) wide, which is a massive jump from its current 52m (~170 ft) maximum. Unsurprisingly it’s looking at carbon fibre to reach these widths.
While not launched officially, Agrifac made no secret of this at the open day, showing a ‘hybrid’ with carbon fibre outer sections fitted to the existing steel one. While there are few details about this prototype, it uses a lattice-work construction, with the nozzles mounted at the top of a triangle.
Targeting greater precision
Under the banner of ‘Need Farming’ Agrifac is promoting a range of systems to apply products with ultimate precision. Top of the technology tree is AiCPlus, which identifies individual plants and applies a specifically-tailored product rate – on the move.
By the way, Agrifac explains AiC is pronounced ‘I See’, with the AI an abbreviation of Artificial Intelligence.
Cameras, mounted along the boom, scan 3m (~10 ft) wide bands of crop in ‘real time’ and, use special software algorithms to interpret what they detect. This could be individual weeds, diseases or pest damage.
Ultimate spraying precision and control delivered by AiCPlus, which uses boom-mounted sensors to identify areas down to 50cm and deliver targeted treatments with single nozzle accuracy.
Applications are targeted using control to single nozzles, which are operated by Pulse Width Modulation (PWM). This enables the nozzles to be turned on/off at up to 100 times/sec, allowing the system to not only vary and apply the dose for the target, but also maintain the correct droplet size for the product.
Solenoid valves switch nozzles on/off up to 100 times/sec and maintain the application rate without changing pressure. The system also reduces flow to the inner nozzles and increases it to the outside automatically during turns.
To accomplish this degree of precision application, Agrifac has introduced a range of other new technology. Along with the sensors and single control there is another new system, DynamicDosePlus (here’s a smartphone video), which implements control down to a resolution of a single nozzle.
Pesticide rates, rather than just the total application volume, are changed on the move using SmartDosePlus. And to ensure products are applied accurately there is StrictSprayPlus, which includes turn compensation.
Precise prescription maps
For precise applications, without using AiCPlus on the move sensing, Agrifac has developed DynamicDosePlus. This, it claims, is the first system to create application plans to one nozzle precision.
As well as planning applications it also executes the operations, not only controlling applications, turning nozzles on/off, but also varying the pesticide rate between 0-100%. To do this AiCPlus requires high precision prescription maps.
Agrifac has developed a completely new high resolution system for creating prescription maps and executing the instructions on machines equipped with single nozzle control.
Mixing on the move
With AiCPlus varying pesticide rates on the move and to one-nozzle precision, Agrifac says it is difficult, or even impossible, to predict the chemical concentration required before application.
To overcome this, it has developed its SmartDosePlus direct injection system. Just clean water is held in the spray tank with the concentrated chemical stored separately. According to required pesticide rates detected by the sensors or stored on the map, the system’s software then meters the precise quantity of active required for the specific area and mixes it ahead of the boom.
The valve system and full boom circulation and priming ensures each nozzle receives the correct mix. It also doesn’t matter how many nozzles are in operation at the time.
It also enables other active ingredients to be added to treat certain areas and turned off when the patch is passed. Similarly, pesticide rates can be reduced dramatically or even stopped completely in environmentally sensitive areas.
Another big advantage of carrying just clean water in the tank, adds Agrifac, is it significantly cuts cleaning time and the amount of washings. This not only speeds up turnarounds between products, but can also help reduce the risk of cross contamination when working in sensitive crops.
The right rate and droplet size
As well as single nozzle control, StrictSprayPlus also provides application volume control that is unrelated to pressure, which maintains the droplet size regardless of changes in forward speed or pressure.
Automatic controllers normally set the application volume, according to speed by varying the pressure. In most cases as speed rises the droplet size reduces, increasing the risk of drift. As the pressure falls the droplets get larger and this may have adverse effect on efficacy.
Pulse Width Modulation overcomes this by using solenoids to turn the flow to the nozzle on/off up to 100 times/sec to maintain the correct application volume. The pressure is unaltered, so the droplet size remains the same.
StrictSprayPlus nozzle control also delivers turn compensation – to maintain the correct application volume when spraying around corners. As the sprayer turns the nozzles on tip of the outside boom move considerably faster than those on the inside of the turn.
With a fixed application volume, this results in under-dosing on the outside and overdosing on the inside. Agrifac says its system detects the speed differences and calculates the rate required for each nozzle across the boom.
But, experts warn, it’s important to note that PWM currently does not work with many of the popular Air-Inclusion (AI) nozzles in use today.
On the level
Regardless of the other technology on board, setting and maintaining the best boom height is crucial to maintaining spray efficacy and cutting drift.
For its new StrictHeightPlus auto-boom height control, which works in conjunction with the BalancePlus and variable geometry on its J Boom, Agrifac has developed new ‘wide view’ sensors.
Three sensors are fitted into four separate clusters, mounted across the boom that, it adds, scan a wider area than other systems. This is said to provide a better overview of the crop as well as help to distinguish between irregularities, misses and tramlines, which can affect performance.
A new auto-boom height control system, developed in house, uses three sensors in a cluster to scan a wider crop area. Four clusters are used on the boom.
The system is also now fully integrated into the firm’s own EcoTronic terminal, eliminating the need for another box in the cab.
More power and control for Endurance II
The Endurance II is powered by a 420hp engine and is equipped with a new, advanced control panel and joystick.
The sleek new EcoTronicPlus II joystick and touch-pad clusters commonly used controls into areas, providing finger-tip control of operations.
While the manufacturer sticks with the Claas Vista cab, inside operators will find a sleek new, modern control panel. Called EcoTronicPlus II, it is designed solely for use on a sprayer and incorporates a stylish joystick ahead of the armrest pad, which is surrounded by touch buttons.
These are accompanied by a single touch-screen, which is used for both the sprayer and the GPS-controlled equipment, such as section control, mapping and even road navigation. The screen changes automatically to display only information that is required for the current operation.
Elsewhere the Endurance II retains familiar equipment such as the existing StabiloPlus chassis, GreenFlowPlus multi-stage centrifugal pump and spray system as well as the 8,000 litre (~2,110 gal.) capacity tank and booms from 24m (~80 ft) to 55m (~180 ft).
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Turn compensation is a feature in pulse width modulation (PWM) sprayers in which nozzle output matches the boom’s speed during a turn. When turning, the inside and outside of a boom travel at different speeds, resulting in over-dosing on the inside and under-dosing on the outside. Read about PWM systems here, here, and here.
The degree of the problem depends on the inside turn diameter. Clearly, the tighter the turn, the more severe the over-and under-dosing. The ability of a PWM sprayer to compensate also depends on the turn tightness, as well as the Duty Cycle (DC) the system is operating at during the turn.
In the above example, a 120 ft boom makes a turn around an object with a 60 ft diameter. Assuming a 12 mph speed and an application volume of 10 gpa, the inside of the boom travels at 4 mph and applies 30 gpa, or 3x. On the outermost nozzle, the speed is 20 mph with an application volume of 6 gpa, or 0.6 x. A sprayer operating at 60% DC would be able to correct the application in this turn by operating at 100% DC on the outside and 20% DC on the inside.
But completing the turn at other DCs may be problematic. In this case, lower sprayer DC would require the inside DC to operate below 20%, which may not be possible, depending on the system. Conducting the turn at higher DC would prevent the outer boom from meeting the flow requirements, resulting in under-dosing.
Optimizing the benefit of turn compensation requires the operator to enter the turn at a DC that meets the objectives. Is it more important to prevent under-dosing of the outside perimeter? If so, slow down in the turn (reducing DC) and maximize the extra capacity at the outside of the boom, possibly at the cost of over-dosing the inside.
Turn compensation is a valuable feature in all agricultural operations where input distribution uniformity is important. Spraying is no exception, and PWM makes it possible.
ExactApply
is an application system capable of PWM, introduced by John Deere in August,
2017, with its first customer field season in 2018. ExactApply offers several
unique features that differentiate it from the existing systems. Here is a
brief description of its major components and capabilities:
Nozzle
Body Design:
The body contains a turret with six numbered nozzle locations, all pointed down, and two solenoids, one on either side of the body. Three nozzle locations are on short feeds (locations 1, 2, and 3), whereas the remainder are on long feeds (4, 5, and 6). The front locations and left solenoid is called “A”, whereas the right solenoid and rear location is “B”.
ExactyApply nozzle body
Nozzles are paired so that A or B or both are capable of spraying at a time, depending on the selected mode. Pairs are 1 & 4, 2 & 5, and 3 & 6. The operator manually rotates the desired nozzle pair into position.
When a short feed (1, 2, or 3) is placed at the front of the body, the system is in Separated Mode. In this mode, the left solenoid controls the front nozzle and the right solenoid control the rear nozzle. Either or both can be used, in pulsing (PWM) or conventional mode, selected through the monitor.
When a long feed (4, 5, or 6) is placed at the front, the body is in Combined Mode. Now, all flow from the right and left solenoid can only exit the front nozzle. Very high flows are achievable in Combined Mode, making it suitable for liquid fertilizer application. It may not have other practical applications in Western Canada.
View from left side of body (solenoids removed). Turret position #4 (tall feed) is in front, and #1 (short feed) is in back, placing the body in Combined Mode.
In Pulsing Mode, each solenoid pulses at 15 Hz, meaning it completes 15 open-and-close-cycles per second. The A and B solenoid timing is offset by 180 degrees, so that the B nozzle is in the middle of its on-cycle when the A nozzle is in the middle of its off cycle. In combined mode, this means that the system operates at 30 Hz.
Adjacent bodies are also 180 degrees out of sync with each other, similar to Capstan, Raven, and TeeJet bodies, so that whenever a nozzle is off, its adjacent partners are on (when operating at 50% DC and above). Another way of saying this is that all even-numbered bodies act together, and all odd-numbered bodies act together but half a cycle later. This results in a blended pulse that prevents skips.
Plunger assembly inside solenoid. Black plastic portion can be removed, exposing poppet and spring.
The proportion of each cycle that the solenoids are open is known as the duty cycle (DC). At 100% DC, the valves are always open. At 50% DC, the valves are open 50% of the time. The minimum DC allowed by the system in default is 25%. This can be lowered to a smaller value within the monitor.
Opened plunger assembly showing tip of poppet (right) and seat (left)Poppet inside plunger assembly is pulled back by magnet inside solenoid 15 times per second
DC is closely related to the flow rate of the nozzle. There are two ways of looking at this. An 08 sized tip operating at 40 psi will have a flow rate of 0.8 US gpm at 100% DC, about 0.4 US gpm at 50% DC, and close to 0.2 US gpm at 25% DC. This feature is primarily useful when sprayer speed is changed, requiring new flow rates without a change in spray pressure.
Pulsing Mode is not available for nozzles sized smaller than 02, or for air-induced tips.
Pulsing can be disabled to allow the use of air-induced or other tip technologies that may not function well when pulsed. This is called AutoSelect Mode.
AutoSelect
Mode:
AutoSelect Mode (“Auto Mode” in 4600 monitor) can be used to achieve three unique flow rates. “A” alone, “B” alone, or “A” & “B”. When properly staggered, a travel speed range similar to Pulsing Mode can be achieved, although pressure will rise within each nozzle as travel speeds increase, as in a conventional system.
In AutoSelect Mode, the user selects a tip for position A, and an incrementally larger tip for position B. The monitor requires that the user inputs minimum and maximum pressures for A, B, and A&B. Travels speeds corresponding to these tip and pressure choices are calculated, and the monitor warns the user when speeds don’t overlap. The user either changes minimum and maximum spray pressures, or selects a different sized tip to eliminate the gap.
AutoSelect Mode is useful when a certain specific tip is required which is not compatible with Pulsing Mode, for example drift protection with air-induced tips.
Pulsing
Mode Nozzle Selection
At this time, John Deere nozzles best suited to the ExactApply’s Pulsing Mode are the LDM, LD, LDX, and 3D. Of these, the LDM most closely represents the spray quality of the LDA and ULD that John Deere operators are accustomed to. The remainder are considerably finer.
ASABE spray qualities for Low-Drift Max (LDM) tips. Being Very Coarse at lower pressures, applicators are advised to use higher spray pressures (50 to 70 psi) when coverage is important.ASABE spray qualities for Guardian (LDX) tips. Note that the smaller sizes (03, 04, 05) produce finer sprays and will require pressures below 40 psi to have any reasonable drift reduction. ASABE spray qualities for 3D tips. As with LDX, the smaller sizes (03, 04, 05) produce finer sprays and will require pressures below 30 psi to have any reasonable drift reduction. Such low pressures may narrow the spray pattern. ASABE spray qualities for Low-Drift (LD) tips. As with LDX, the smaller sizes (03, 04) produce finer sprays and will require pressures below 40 psi to have any reasonable drift reduction.ASABE spray qualities for the Low-Drift Twin (LDT). Comprised of two same-sized LD tips assembled in a TwinCap.
Proper sizing for PWM requires that tips be sized for about 20 to 40% extra capacity. In other words, at expected average travel speeds, the pulsing duty cycle should be approximately 60 to 80%. The following chart has a highlighted column at 70% duty cycle for that reason. Assuming an ExactApply operator expects to apply 5 gpa and travel at 15 mph on average, possible nozzle options (highlighted in yellow) are:
03 at 60
psi
04 at 30
psi
05 at 20
psi
06 at 15
psi
Calibration chart for PWM systems. Nozzles are sized at about 70% Duty Cycle (grey column). Options for 5 gpa at 15 mph are highlighted yellow. Black highlights represent speeds >25 mph, not available.
The best
choice will likely be either of the first two options, as the third and fourth
have spray pressures which are probably too low for good nozzle performance.
The decision would depend on the spray quality obtained for each of the
remaining two options.
Of
course, spray pressure can be altered to suit the operator’s spray quality
requirements. This merely affects the available speed range as well as the DC
at which the system operates at a given target speed, possibly affecting
Pulsing Mode utility.
The row of speeds adjacent to the selected nozzle and pressure identifies the approximate travel speed range that can be expected, from 25 to 100% DC.
It’s important to know your current DC to be sure the system is operating properly, and also to take full advantage of turn compensation features. We’ve described a way to place a DC display module on your home screen here.
The application volume can be changed to suit the specific use, the chart’s speed values are updated automatically. Make sure the nozzle spacing at the top left is correct for your sprayer
Pressure
Drop across Solenoids
PWM
solenoids represent a restriction to flow, and may cause a pressure drop. John
Deere has published the pressure drop, and it is shown in the above chart
(download version only). The pressure drop is fairly low, only 2 psi for an 04
tip operating in separated mode at 40 psi. For an 06 tip, the drop is 3 psi,
and for an 08, it’s 6 psi. a #10 tip has a 10 psi drop at 40 psi. These
pressure drops must be added to the operating pressure of the sprayer. Pressure
drop is important because the LDX, LD, and 3D tips will be operated at low
pressures to obtain coarse sprays for drift protection. Operating an 08 tip at
20 psi (at which pressure it has s drop of 3 psi) will result in in a tip
pressure of 17 psi. Since we are at the low end of a nozzle’s operating range,
pattern stability may be compromised when the drop is not taken into account.
Why 70%
Duty Cycle?
An operator of any PWM system needs to know their current duty cycle. On ExactApply, a module can be installed on the home screen that provides a visual display. We show how to do this here.
There are
five main reasons a nozzle should be sized to run at approximately 70% DC. The
first is to provide speed flexibility. An operator may need to speed up somewhat,
but usually not more than 30%. On the other hand, slowing down is much more
common to accommodate challenging terrain, and a factor of two to three is
possible (from 70% DC to 25% DC).
Secondly,
drift reduction through lower spray pressure usually requires less speed due to
the associated lower flow rate. With some DC room to spare, the loss of flow
can be corrected without requiring a speed change.
Thirdly,
spot spraying at a slightly higher rate is possible, again through DC alone.
Fourth,
Nozzle Rate Boost of up to 25% for up to six nozzle locations is possible
within the monitor, but only if the system is operating at 75% DC or less.
Finally,
turn compensation, during which the outside boom travels faster than the
tractor unit and the inside boom slower, requires this additional capacity.
More on turn compensation here.
AutoSelect
Mode Nozzle Selection
AutoSelect
Mode allows for three flow rates to be used in succession: A, then B, the AB.
The key to success is to use small size increments between A and B, and to use
tips that have a wide pressure range.
In the
example below, the A location was an 02 tip and the B was an 03, for a total of
05. Pressure was not allowed to drop below 30 psi to retain good patterns.
Pressure at switch over to the next largest flow rate therefore needed to be 80
psi to make the moves possible without pressure gaps resulting in
over-application. As a result, the spray quality can be expected to fluctuate
three times as the sprayer accelerates through A, B, and AB in succession.
Nozzle
selection should seek to emphasize the middle of the pressure range of either B
or AB to avoid unnecessary fluctuations.
Spray pressure and travel speed as Auto Mode moves through A, then B, then both A&B
Download an Excel sheet that assists in nozzle selection for Auto Mode here.
A
maintenance kit comes with each ExactApply sprayer. It contains two spare
plunger assemblies, clips, and pins, as well as a brush, an O-ring picker, and
a torque driver.
Maintenance kit
The
ExactApply body is fairly easy to take apart for servicing. Hair pins at the
back of the unit secure each solenoid, and both pull out easily. The plunger
assembly can be disassembled without tools. Take care not to drop the poppet
spring!
Reassembly
of the plunger requires the use of the torque driver fitted with a 17 mm
socket, included in the kit. Do not over-tighten the plastic component.
Aside
from the manual rotation of the turret to select a different nozzle
combination, the only moving part in the ExactApply body is the poppet in the
plunger assembly. This piece is the valve that controls flow rate, and opens
and closes 15 times per second whenever pulsing mode is on, moving like a
piston in a cylinder. Debris (sand, fertilizer crystals, etc.) can interfere
with the seal of the poppet against its seat, and good filtration is important.
In the first generation, metal flakes began appearing inside some plunger assemblies . A coating de-laminates off the sleeve and can cause the plunger to stick. This has been starting at 800 h of use. The springs have also been observed to break. This problem has been addressed in newer generations.
Metal flakes interfering with plunger actionPlunger damage showing likely source of metal flakesBroken plunger spring
Certain formulations may build up a residue that interferes with poppet movement. It’s impossible to predict all possible formulation impacts, but oily formulations such as emulsifiable concentrates (EC, milky appearance) are likely to be more problematic than solutions (S, clear appearance). John Deere recommends a daily rinse of the boom through both the A and B valves with Erase, a tank cleaner product. Fortunately, the R series sprayer allow for boom flushes from the clean water tank even when the product tank has product in it.
Each nozzle body contains ten O-rings and two sets of seals. The turret assembly has two large rings, and each plunger assembly has four. Care needs to be taken to prevent damage to these rings to prevent leaks.
O-rings in nozzle body
Some
Recommendations
The
ExactApply system is very full featured and customers new to PWM can be
overwhelmed by the number of choices at their disposal. Let’s simplify the
system and make some basic recommendations.
Pulsing mode is likely to be the most useful feature of the system. Plan to use this feature for most spraying operations.
In Pulsing mode, select from John Deere’s LDM, LDX, LD, and 3D tips. The LDX, LD, and 3D offer similar Medium spray qualities and should be operated between 20 and 40 psi to produce lower-drift sprays. Check spray patterns at these pressures and ensure that 100% overlap is achieved (pattern width is twice nozzle spacing).
The LDM (Low Drift Max) is coarser than the above nozzles (comparable to ULD or LDA) and is available in 03, 04, 05, 06, 08, and 10 sizes. This will be the tip of choice for pulsing mode and can be used at higher pressures to ensure good pattern formation.
Separated mode can handle most flow rates, and offers the flexibility of choosing A (front tip) or B (rear tip) or both. This means turret 1, 2, or 3 will be in the forward (A) location.
Equip the A location with your low volume tip (say, 5 gpa). Place the high volume tip (say 10 gpa) at the B location. Use both together for late season sprays into dense canopies (in this case, A&B=15 gpa)
Twin tips for Fusarium Head Blight (FHB) can be achieved in five different ways.
3D tips in “A” or “B”, alternating their orientation along the boom (forward, backward, forward…). Pulsing Mode. (Since these tips are not very coarse, low pressures are needed to ensure that the angle of the spray persists more than a few inches).
3D tips in “A” and “B” on each body, front facing forward, rear facing backward, and operating in A&B. Pulsing Mode.
LDT (Low Drift Twin) in “A” or “B”. LDT is a TwinCap with two LD tips installed. Pulsing Mode.
LDM (Low Drift Max) in installed in a TwinCap in “A” or “B”. These are coarser sprays that will retain their direction longer and are well suited for FHB. Pulsing Mode.
GAT (GuardianAIR Twin), an air-induced tip, running in either conventional “A” mode or in Auto Mode but sized for “B” (avoid operating in A&B to prevent pattern interference).
Some recent recommendations: A customer wanted tips for 5, 10, and 15 gpa at 14 mph, and the 15 gpa was for FHB. He didn’t want to be too coarse. We recommended the LDM 03 at 60 psi (5 gpa) in “B”, the 3D 08 at 30 psi (10 gpa) in “A”, and both together, with the 3D facing forward, for FHB for 15 gpa. The sprays would be “Coarse”, a nice middle ground.
ExactApply joins Capstan PinPoint II, Raven Hawkeye, and WEEDit Quadro, Agrifact StrictSprayPlus, and TeeJet DynaJet with PWM capable systems. Auto Mode is a version of nozzle switching first introduced into the market as Arag Seletron and Hypro DuoReact. It appears to be a full-featured system that is fully integrated into the new John Deere 4600 display but is also available as a retrofit on the older R-Series 2630-equipped sprayers.
One of the more perplexing questions in tank cleanout is knowing when the cleaning process is good enough to prevent harm. This question is especially relevant to producers that grow canola and use Group 2 herbicide products, or grow soybeans and use dicamba on some of their area. In both of these examples, crops can be extremely sensitive to very small residues.
When does an applicator know that the cleaning job was good enough? In about two weeks! There is no easy way to tell, except to be precautionary.
A bit of math can help put us in the ballpark. First, we need to know the tolerance of a crop to the herbicide, preferably expressed as a proportion of the tank mix to be cleaned. Let’s use dicamba as an example. It’s been reported that non-dicamba tolerant soybeans can show leaf-cupping symptoms from dicamba at rates as low as 1/20,000 of the label rate.
Recall that sprayer cleanout is really two separate processes that we’ve written about here, here, and here. The first is dilution of the remaining volume in the system. The second is decontaminating specific sprayer components (filters, boom ends, hoses). We’ll focus on dilution in this article.
If you’re diluting, the second piece of information you need is how much liquid is left in the sprayer when you start cleaning. All sprayers have a certain amount of liquid left in the tank and associated plumbing after the tank is empty. The sump, the suction line feeding the pump, and the lines returning to the tank via agitation or sparge are most common. Even when the pump no longer draws liquid, those lines retain some volume of product. This volume can’t be pushed out to the boom, most of it goes back to the tank.
The volume of this “remaining liquid” is likely somewhere between three and thirty US gallons.
The remainder volume depends on the sprayer, and also how the tank is emptied. Some applicators simply spray until the solution pump pressure drops, others choose to drain the remaining liquid from a sump valve. When draining, product should be captured in pails rather than allowing it on the ground where it will harm the soil and possibly make its way into runoff.
It’s always preferable to spray the tank empty in a field.
As we’ll see below, a low remaining volume greatly improves the efficiency of the dilution process. It’s a sprayer feature that should be considered at purchase.
The table below has some sample calculations. Note that the paired cases (1&2, 3&4, 6&7) all use the same total water volume, but compare a single vs triple rinse of three different remaining volumes.
Comparing Case 1 to Case 3 or Case 6, (remaining volumes of 10, 20, and 50, respectively), it’s clear that minimizing the remaining volume is important.
It’s also striking that the same amount of clean water, subdivided into three smaller repeat batches (Case 2, 4 and 7), is much more powerful than using single batches with the same total clean water amounts.
Reducing the size of each batch even further and increasing the number of batches (Case 5) approaches what a properly executed continuous rinse can do.
Is it necessary to dilute to the level that’s safe for the next crop? Not always. The next product in the tank acts to dilute the remainder once again, possibly by a factor of 100, depending on the remaining volume and the tank size (Case 8). The material in the boom, however, won’t be diluted by this additional volume, and therefore may harm the crop unless it is first sprayed out elsewhere, especially when section ends are not drained and rinsed.
This is where a recirculating boom is valuable, providing an opportunity to charge the boom without spraying. The penalty is that the boom volume is then returned to the tank in the process, increasing the amount that needs to be diluted.
Let’s return to the dicamba example with a 20,000-fold dilution requirement and a 1,200 gallon tank. We’ll consider two examples. In the first, the operator wants to prime the boom in the soybean field without any harm to the dicamba-susceptible beans. A 20,000-fold dilution is needed.
We’ve looked at five options that each assume a remaining volume of 10 gallons. Note that our goal is the same – dilute by a factor of 20,000.
The formulae:
Dilution per Rinse = final dilution ^(1/# of rinses)
The maximum amount of dilution possible with a 1,200 gallon tank and a 10 gallon remainder is 120 (see Row 8, Table above).
One rinse diluting by 20,000 – impossible with a 1,200 gallon tank (max achievable is 120-fold);
Two sequential rinses each diluting by a factor of 20,000^(1/2) = 141. Also impossible with a 1,200 gallon tank;
Three sequential rinses, each diluting by a factor of 20,000^(1/3) = 27. A volume of 260 gallons can do this (27*10)-10=260 gallons. For three rinses, the total volume is 780 gallons.
Four sequential rinses, each diluting by a factor of 20,000^(1/4) = 12. A volume of 110 gallons can do this, for a total volume of 440 gallons;
Five sequential rinses, each diluting by a factor of 20,000^(1/5) = 7. A volume of 60 gallons can do this, for a total volume of 300 gallons.
The first two examples don’t work because the tank isn’t big enough. But the three remaining examples all work equally well, they just consume different amounts of clean water.
If that doesn’t seem like a lot of work, then repeat this calculation with a 30 gallon remainder volume, common on many sprayers. Short on time? We did it for you here.
Second, let’s assume the operator is prepared to prime the boom where it doesn’t harm soybeans. Now the first new product tank takes care of the last dilution, lowering the cleanout dilution requirement by 1,200/10 = a factor of 120. Now the cleanout dilution requirement is only 20,000/120 = 166.
One 1,200 gallon tank rinse can only achieve 120-fold dilution.
Two rinses, each diluting by 166^(1/2) = 13. Rinse volumes of 120 gallons are sufficient, for a total of 240 gallons.
Three sequential rinses, each diluting by a factor of 166^(1/3) = 6. A volume of 50 gallons can do this, for a total volume of 150 gallons.
The math is simple, and can be done using the formula in the first table, or this app:
The hard part is knowing what the remaining volume is. It would be very useful for a manufacturer to provide this information.
In the meantime, you can estimate on your own. Add water with surfactant to your tank, and spray it empty. While spraying, turn the agitation on and off to fill and activate the sparge, if equipped. Once the tank is empty and the spray pressure drops, stop and drain the sump into pails. Ensure that the pump suction line and the pressure line up to and including the agitation and sparge lines also drain. Disconnect these if necessary. If there is a filter housing in this circuit, remove it as well. Avoid collecting liquid from the pressure line beyond where the the agitation or sparge split off, as this will be pushed out to the boom.
An alternative is to estimate the length of hose in this circuit, using the following table as a guide:
And remember, diluting the remaining liquid is only one part of a cleaning process.
Note: This article was written by Bob Wolf of Wolf Consulting and Research, and first appeared as an NDSU Extension Service publication. Bob has agreed to reproduce the article on our website.
When applying crop protection products, a good steward is one who can identify and record the environmental factors that may negatively impact making an application; particularly, the possibility of spray drift.
New label language states: “Avoiding spray drift at the application site is the responsibility of the applicator.” A wise sprayer operator must possess the ability to assess the environmental conditions at the field location to determine how best to spray the field, or maybe decide it would be best not to spray that field, or part of that field, at that time. Instruments that assess environmental conditions are available to assist applicators in making good decisions.
Making the correct measurement is the critical first step. Record the information measured to document the application conditions. Quality records help mitigate against any misapplication allegations, such as a drift complaint. Many of the items listed below are based on past legal experiences with applications involving spray drift litigation.
The following guidelines should help you measure and accurately record environmental conditions at the application site.
1- Document any instrument used by recording the manufacturer and model number. Accurate portable weather instruments are recommended. Portable weather instruments are available that log and store data, and aid in auditing and recordkeeping. Some will have Bluetooth/wireless capabilities.
2- Environmental measurements include wind speed and direction, temperature, and relative humidity.
3- At a minimum, record data at the start and finish of the job. Consider more often as conditions change or for a job that lasts over a longer period. For example, make observations when tank refilling for larger fields. Time stamp all observations with a.m., p.m., or military time.
4- Take meteorological readings as close to the application site as possible. Be advised that the weather data received via a smart phone or local weather station may not be accurate for the location being sprayed.
Note the specific location where the measurement was made, such as GPS coordinates, field entry point, field location, etc. Check the label to see if it requires a specific observation location in relation to the treatment area.
5- Make all measurements as close as possible to the nozzle release height (boom height) and in an area not protected from the wind by the spray machine or your body. For aerial applications, six feet is suggested when using a hand held instrument.
6- Record wind speed averaged over a 1 to 2 minute time span. Note the time the observation was recorded. Most instruments give an average over a period of time. Make sure the instrument’s anemometer is facing directly into the wind.
Do not record winds as variable or with a range i.e. 4 to 8 mph – an average gives a better indication of the transport energy. Light and variable winds, where directions may change several times over a short period, can be more problematic than higher speed winds in a sustained direction. Observe any label restrictions on wind speed.
Wind direction requires a similar averaged measurement. Record direction in degrees magnetic from a compass (0-360°). The use of alphabetic characters, i.e., N, S, NW, to indicate wind direction is discouraged. The key for determining direction is to have an accurate assessment method: trees moving, dust, smoke, a ribbon on a short stake, etc. Face directly into the wind and record the direction from which the wind is coming. A ribbon on a stake with the ribbon blowing directly at your body is a simple fail safe approach. Movement of smoke, particularly from moving aircraft, or dust may help determine direction.
7- Record temperature and humidity since they can be helpful in determining temperature inversion potential. It may be advisable to record both temperature and humidity well before and after the application for this purpose. In fact, recording a morning low and an afternoon high would be useful regarding determining the potential for an inversion. Take temperature measurements with the instrument out of direct sunlight. Shade the instrument with your body or spray equipment. This is especially critical if you are trying to assess temperature differentials for determining if an inversion is in place.
8- Be alert to field level temperature inversion conditions which typically occur from late afternoon, can be sustained through the night, and into the next morning. Beware, inversions can start mid-afternoon. Observe conditions such as the presence of ground fog, smoke layers hanging parallel to the ground, dust hanging over the field/gravel road, heavy dew, frost, or intense odors (i.e., smells from manure or stagnant water from ponds are held close to the surface when inversion conditions exist). Inversions commonly occur with low (less than 3 mph) to no wind speeds. Spraying in calm air is not advised. If a mechanical smoker is used note wind direction and smoke dissipation with a time stamp.
9- Note any variances due to terrain or vegetation differences, tree lines, buildings, etc.
10- Initial or sign all recordings to indicate who made the observation(s).
