The John Deere ExactApply system has a pulsing feature, more commonly known as “Pulse Width Modulation” (PWM). From the operator’s perspective, it’s important to know the Duty Cycle that the system is operating at. The Duty Cycle (DC) is the percentage of time that the pulsing solenoids are “on”, or flowing. At the average travel speed, the pulsing system should operate at 60 to 80% DC for optimum performance. For in-depth explanation of ExactApply, read here.
Unlike its PWM counterparts (Raven Hawkeye, Capstan Pinpoint), the new John Deere 4600 monitor does not display the DC by default. Fortunately, it offers a module for insertion to its run pages.
The module isn’t perfect, and inserting it into an active run page is torture.
Here is how to bring this module onto a 4600 screen:
1. On 4600 Monitor, click on “menu” (bottom right).
2. Select “Applications” tab.
3. Choose “Layout Manager”.
4. Edit Run Page Set.
5. It’s easiest to copy an existing Run Page, rename it, and then customize its modules.
6. Make room on new Run page for new module. On my copy of the “Spraying” run page, I’ve deleted a module on the bottom left that I have elsewhere. Now “Add Module”.
7. Select “Machine Settings” tab, then “Boom & Nozzles”.
8. Scroll down to “Section Flow %” (four windows) and “Add Module”.
9. Module is placed in available open area. There is a warning if not enough screen space is available.
10. Save new Run page. Make sure it’s part of the “Active Run Page Set” in Layout Manager so it’s available to scroll to while spraying.
The module is a bar graph that gives you relative DCs along boom. In the first example, we’re driving straight and everything is fine. After a couple of shoulder checks, we pull out the smartphone and take a picture.
The bar graph format is useful during turn (left in this example, forcing higher DC to outside of boom, the right).
If it plateaus on outside (as in tight right turn, below), you are under-applying on the outside since the DC can’t go higher than 100%. Slow down and that improves it because it lowers the duty cycle of the entire machine.
Slowing down may cause too low a DC, resulting in over-application on inside of boom because the DC can’t be reduced below 15%.
Remember, for Turn Compensation to work, make sure the box is checked (Menu|Boom & Nozzles|ExactApply Config/Spray Mode|Manual Setup|i|<down four screens>|Turn Compensation Check box). While you’re there, make sure the “Limit Minimum Flow %” is unchecked. This lets DC go down to 15%, from 25%.
Capstan Ag brought Pulse Width Modulation (PWM) to spraying in the mid 1990s. Over the past 20 years, it has become commonplace on Case sprayers as AIM Command and AIM Command Pro, and as an aftermarket product, called Sharpshooter or PinPoint, on any brand sprayer. If you’re new to the concept, read about it here and here.
A sprayer turn, without turn compensation. Note the darker dye on the innermost nozzles and lighter deposits on the outer wing.
The latest versions (AIM Command Pro and PinPoint) offer turn compensation and individual nozzle sectional control. But there remains a large base of older AIM Command units that lack turn compensation. And of course, sprayers that lack PWM alltogether, possibly because of cost.
The Capstan EVO addresses both issues. Introduced in January of 2019, it gives older AIM Command units affordable turn compensation. As a bonus, a complete new EVO install on non-PWM sprayers is available at a significant discount compared to most other PWM products.
EVO features many of the same basic PWM capabilities as its bigger cousins, but with a shortcut, explain Capstan representatives.
As always, a change in travel speed changes the duty cycle of the pulsing solenoid, adjusting flow rate of the nozzle without a change in pressure. This provides the consistency in performance that we love about PWM. Drift or coverage are controlled by the operator who makes changes to spray pressure from the cab, with a commensurate background adjustment in duty cycle so that travel speed is unaffected.
With the EVO, the shortcut is that sectional control is by plumbed section. Technically it’s possible to add sections, but the rate controller and the sprayer wiring would have to allow it.
Spray dosage for sectional turn compensation for six sections of equal size, with the centre of each section applying the target dose. As always, some lateral movement of spray from adjacent nozzles will occur.
Turn compensation is part of EVO, and this is an important benefit that was previously only available in more expensive versions of a PWM product. Each section will have a fixed turn compensation based on the speed of the centre of the section. Its performance will depend on the size of the sections.
For a 100′ boom with six 10-nozzle sections turning around an object with a 60′ diameter, our modelling shows that the deviation from perfect turn compensation is least on the outer wings (where it’s most important) and grows towards the inside of the turn. In this example, the outer section’s end nozzle under-applies by 6% relative to the ideal, and the innermost nozzle on this section over-applies by 7%.
On the next section, these deviations are 7% under and 8% over, then 8% under and 9% over.
Moving from the centre of the sprayer to the inner wing, deviations are 9% under and 12% over, then 12% under and 16% over, and finally 16% under and 24% over.
Spray deposition on an un-compensated turn.
On an uncompensated boom with the same dimensions, the outermost nozzle would be under-dosing 38% and the innermost nozzle would be over-dosing by 267%.
Recall that it’s more important to be accurate on the outer wing than on the inner, for the purpose of delivering the full spray dose in a turn.
Repeated year-after-year under-dosing at the periphery of a turn such as field corners, or around permanent features such as sloughs, trees, or stone piles results in weed problems.
EVO is intended for users with an original SharpShooter or AIM Command who would like turn compensation but don’t want to a whole new PWM system. EVO provides new modules and a new screen, but users save money because they can keep their existing solenoids, says Capstan.
Capstan says that EVO is for every brand of sprayer ordered without pwm control from new to 15 years old. It’s an easy upgrade for owners of AIM Command & SharpShooter systems because these already have most of the components, and install times are therefore lower for these machines. Existing solenoids and wiring harnesses can be retained.
Owners of high clearance pull type sprayers will also see the advantage of turn compensation and pressure control at an attractive price point.
EVO modules and tools needed for installation
I was present during an installation of these new modules on an existing Case 3330 sprayer with AIM Command. It took one person, with occasional assistance from a second, less than 1 h to do the conversion.
Removal of AIM Command modulesInstallation of EVO board containing all modules and replacement plugins
A new installation would require an additional several hours to install wiring harnesses and solenoids. Times will vary with sprayer model and technical experience of the installers.
The EVO electronics run in parallel to the existing sprayer monitor. It allows the existing monitor to control sections and determine the flow requirements. It does not control pump speed, it simply reads the flow, pressure, and gps signal from the sprayer’s systems and uses them to determine the duty cycle (DC) that ensures the spray pressure remains constant. On AIM Command units, the pressure control module remains installed and pressure adjustment remains possible through AIM Command in cab controls.
Entering system settings into new EVO monitor
It’s possible to set the pulsing frequency between 3 and 30 Hz in EVO, an industry first. The lower the frequency, the wider the dynamic flow rate. Capstan advises to maintain a frequency above 10 Hz for spray operations. Lower frequencies may be used for fertilizer applications, where prescription maps require a higher rate range and where uniformity requirements are more relaxed.
EVO Monitor contains an option in which to select pulsing frequency
Testing of completed EVO Installation
The monitor has an intuitive readout of average DC and a bar graph showing the DC across sections in a turn. If this bar maxes out on the outer sections during a turn, simply slow down to lower average DC and provide extra capacity to those sections.
EVO monitor during operation. Readout includes current spray pressure, duty cycle, and turn compensation status.
Lowering the cost of PWM makes it attractive to a new group of users. It also offers a more affordable upgrade path for owners of AIM Command or SharpShooter systems that currently do not have turn compensation.
Spray application by drone is here. It’s common practice in South East Asia, with a very significant proportion of ag areas now treated that way. Estimates from South Korea, for example, suggest about 30% of their ag area being sprayed by drone. It’s in the US, too. The Yamaha RMax and Fazer helicopters, which pioneered drone spraying in Japan dating back to the mid 1990s, have been approved for use in California since 2015. DJI, the world’s largest drone manufacturer, introduced their ag model, the Agras MG-1, to North America in 2016. Many other spray drones are available or in development.
As William Gibson, the author of Johnny Mnemonic, once said,
“The future’s here, it’s just not widely distributed yet.”
DJI Agras MG-1 spray drone (Source: DJI.com)
Proponents of drone spraying cite a drone’s ability to access areas where topography is a problem, such as steep slopes, where productivity of manual application is much lower, or low areas where soil moisture prevents ground vehicles. Operator exposure is reduced compared to handheld application.
Opponents talk about productivity and cost factors compared
to manned aerial application, spray drift, and rogue use.
Before drone spraying becomes commonplace, two important
things need to happen.
Federal laws need to be updated to accommodate the unique features of remotely piloted aircraft systems (RPAS), as they’re now called. Current laws make many assumptions unique to manned ships, and the process to correct that will require some patience. A thorough review for US laws, and their shortcomings, can be found here.
Federal pesticide labels need to permit the use of drones for application. As of August, 2021, Canadian labels have no such registered use.
There is no doubt that we need to prepare for a future that includes spraying by drones. Features such as topography adjustment for height consistency and autonomous swath control are already essentially standard, and the capabilities that improve control and safety will continue to develop.
And yet I’ve been nervous about the prospect of pesticide application with drones. My primary concern is around – you guessed it – spray drift. Because a drone payload is relatively small (about 5 to 25 L, depending on the model), application volumes will need to be low to have any sort of productivity. How low? For manned aircraft with a 200 to 600 gallon hopper, 2 to 4 US gpa (18 to 36 L/ha) are the lowest commonplace volumes. The lower volumes require a Medium spray quality (among the finer sprays in modern boom spray practice) to achieve the required coverage.
It’s a simple concept: the less water is used, the smaller the droplets need to be to provide the necessary droplet density on the target. Drift control with coarser sprays requires higher volumes, and true droplet-size-based low-drift spraying can’t really happen at volumes less then, say 5 to 7 US gpa.
At 2 to 4 US gpa, a drone would be able to do perhaps 1 acre per load. While OK for spot spraying, it represents a serious productivity constraint for anything larger. There will be a push toward lower volumes, perhaps 0.5 to 1 gpa (5 to 10 L/ha). The only way these will provide sufficient coverage is with finer sprays, ASABE Fine to Very Fine, with expected problematic effects on off-target movement and evaporation. These fine droplets are also more prone to the aerodynamic eccentricities of aircraft.
Vortices from the rotor can create unpredictable droplet movement (Source: kasetforward.com)
The current regulatory models for aerial drift assessment in North America, AgDISP and AgDRIFT, are not yet able to simulate drone application. But by entering finer sprays into these models for their conventional manned rotary wing aircraft, we can see that buffer zones will be higher. Much higher. And that outcome will give pause to regulators. Failure to control the movement of a spray is, and should be, a problem.
Estimated Buffer Zones (calculated by AgDISP) for a reference rotary wing spray aircraft, using three pesticide toxicologies and two spray qualities.
Furthermore, ultra-low volume (ULV) sprays can change the efficacy of some products, and these will require new performance studies. At this time, regulators are seeking information not just on spray drift, but on product efficacy, operator and bystander exposure, and crop residues.
Regulators are currently collecting spray drift and efficacy data from drones. Since the drones available in today’s market do not conform to a common design standard like fixed or rotary winged manned aircraft, each model may have its own characteristics and need its own study. Some will have rotary atomizers, others will use hollow cone hydraulic sprays. Some will have electrostatic charging, others may propose special adjuvants.
Once data are assessed, there will likely be restrictions in flight height, flight speed, wind speed, spray quality, water volume, perhaps air temperature and relative humidity (or Delta T). This is not new to spraying, as current labels already constrain use for both ground and aerial spray application, more so for aerial.
The obvious question is how these proper application practices can possibly be assured. Operators will need more than just regulatory approval to use a drone, they will require proper training, similar to what a commercial aerial applicator now receives prior to operating a business.
Recall that our aerial applicators are governed by national organizations, the NAAA in the US and the CAAA in Canada. These organizations are in regular contact with federal regulators to assure compliance. They also help fund research into application efficacy and safety. They organize conferences in the off-season and calibration clinics in the growing season. At these, flow rates are confirmed and deposited droplet size is measured. Spray pattern uniformity is assessed and corrected as necessary.
Should drone applications be exempt from these controls? I don’t think that would be wise. Are we ready to implement them? Absolutely not.
These requirements would change the drones’ economic model. And despite these precautions, a drone may still leave the control of a pilot due to unforeseen technical or human events.
In the US, Yamaha does not sell their drone helicopters. Instead, they deploy their own teams to make the applications. This way, they have assurance that only trained and experienced pilots use the technology.
As the industry gears up for the first registrations, we see drone service companies take a leading role in testing. Much is being learned via legal applications of liquid micronutrients, for example, or limited use of pesticides under approved research permits. And I’m pleased to see the recognition of drift management in these efforts through the use of low-drift nozzles. We are off to a promising start.
Requests for drone use are in progress at our regulatory agencies. The outcomes of their risk assessments will provide important initial guidance, and food for thought and discussion. In the meantime, the drone development continues at a rapid pace, with new features and greater capacity at each iteration.
This week I spoke with Gerry Bell, a producer from near Gravelbourg in southern Saskatchewan (a beautiful town with a historic downtown, church and school, also, home of the Gravelbourger at the local diner). He told me about a project he recently completed, converting his older pull-type sprayer to a granular spreader. It’s a great project, worth sharing.
The concept was first popularized by Manitoba farmer Kyle Holman in 2012, who uses the #SprayMar hashtag on Twitter to promote it.
I will say that i do have the original #SprayMar since I did coin that, but I did not build the original pull type device. We saw 1 online after we built it but dad had been thinking of it for yrs. #WhatCouldHaveBeen
Gerry wrote his project up for us and I’ve posted his description below.
Bourgault 1460 Field Sprayer
The sprayer sat in a machine shed from 2011 when we purchased a Patriot 4420 sprayer. For many years we wondered if we couldn’t find a use for the sprayer as Bourgault had build a very rugged unit. So, in 2017 we decided to mount a Valmar tank (now owned by Salford) on the sprayer frame to be used for granular herbicides and granular fertilizer applications.
Bourgault 1460 (Source: Bourgault.com)
The liquid tank and plumbing were removed as well as the
secondary boom with the wet boom. A few modifications to frame were made but
for the most part the frame was left as is. The unit was painted with the Salford
colours. (Case IH red)
The Valmar/Salford unit is a ST8 which is used lots in
Eastern Canada and the States for strip tilling for applying granular products.
We purchased the tank, hoses, splitters and deflectors from Salford.
The unit as purchased had the following features:
8 imperial tons (16,000 lbs)
Stainless steel tank and duct systems
Mueller Hydraulic metering system with two sets
of rollers – one pair for granular herbicides and one pair for granular
fertilizers
Two hydraulic driven air fans – usually just one
fan but we chose two fans – one for each boom
Weight scales for tank
ISOBus system with mapping, auto on off,
sectional control (one for each boom)
18 outlets – 9 outlets on each side of tank
We designed unit in consultation with Salford engineers:
Each of the 18 outlets has a 2” flexible hose from the tank going to 2” stainless steel tubing stacked on the boom frame
Just prior to the deflectors each 2’ tubing is split into two 1-1/4 streams with special splitters supplied by Salford (according to Salford these are commonly used and have an accuracy of less than 2-3 % variation if mounted properly). Need to be horizontal.
The deflectors are mounted every 30” along the length of the boom (36 deflectors)
The sprayer boom was cut down from 110’ to 90’ to give the correct spacing
Comments on use of
the unit
Functionality seems to work very well as designed
Weigh scales, GPS, mapping, auto on/off, sectional control a real plus compared to original field sprayer with none of these features
Accuracy of product metering seems very good
Distribution across length of unit seems very good
Travel speeds of 10 mph
Product takes 2.5 seconds from time meter starts turning until product reaches far end of boom
There is a difference of about thirty feet in travel distance with start and stop of product on the ground between inner side of boom and outer end of boom. Therefore, we have set look ahead time at 3.3 seconds and shut of time at 0.3 seconds.
Load products with a belt conveyor in yard
Apply 100 lbs of elemental sulphur (0-0-90) on
25% of the crop land each year
(Tank does 160 acres)
Applied Avadex at 12.5 lbs per acre last fall on
some acres prior to snow.
Apply Edge at 20 lbs per acre each fall just
prior to snowfall (for pulses)
Tanks holds 10 minibulk bags – 12,000 lbs, and does 600 acres. On a long day have put out 1200 acres of Edge.
We did extend the axles and also put on new hubs and new tires which were a bigger size. A Bourgault 1850 with 1600 gallons would have worked better but it is hard to find them. Plus they would probably have needed new tires anyways.
It took a lot more time than we had imagined to build but that is true of most building projects. But I would say that we are very happy with the results. It is a pleasure to operate and appears to serve our needs very well.
In almost all agronomic practices, timing is key. There are certain, and often small, windows of opportunity for getting a task done without losing yield potential or product quality. Weed specialists talk about early weed removal, pathologists talk about symptom monitoring, and entomologists remind us of economic thresholds. Acting at the right time is fundamental.
Sometimes I’m asked about comparing two different methods of
spray application. I usually dodge these questions by advising to choose the
one that gets the job done on time. “An average application at the right time
is much better than an excellent application at the wrong time” is how I put
it. Sure, I’m dodging, but I really believe that. It’s mostly in the timing.
Everything we do carries with it some time inefficiencies.
Some are rooted in technology, others in habits. It’s the habits that are
easier and cheaper to address. That’s why, when evaluating how to improve a
spraying operation, I advise to start with a stopwatch and notepad, not a
sprayer brochure.
A stopwatch and notepad provides your path to greater productivity.
Remember, if you want to improve a system, you first need to understand it. And to understand it, you need to measure it.
So, do a time accounting. You need to know how your time is used on a spray day. Note the time spent preparing for the job (loading supplies, double checking label instructions, transporting, etc.). The big users of time are sprayer transporting, filling and cleaning, but there are very many small time users and those can add up. This time is doubly important because these tasks occur during the spray day, when the weather is good and you should be maximizing spray time.
Make your own time accounting sheet, including every detail or possibility.
Even within any one operation, time can be subdivided. How
much time is spent on a turn? Since a 120’ sprayer will make about 22 of these
per half mile, that can add up. Even a spray monitor can play a productivity role
if it quickly and consistently locks onto its swath. Needing to stop and back
up while it searches for a signal can be costly.
On our farm, we sometimes used custom operators to get the cereals off. I recall how aggravating it was to watch the 8820 inch ahead of my N6. Surely it must be throwing a lot over, I thought (it was). But I usually caught it at the truck, where my unloading speed was over 1 minute faster. Redemption, briefly.
That same principle applies to these small efficiencies. A well-designed tender truck can speed loading and more than make up for lower spray productivity of a smaller sprayer. A lighter sprayer load and flotation tires can save a ton of time if it means the difference between getting stuck or cruising through that spot. A set of extra-coarse nozzles that can be rotated into place in just two minutes can help finish a field if the weather changes, or allow a margin to be sprayed, saving a return trip.
Extra nozzles to allow spraying in higher wind speeds without increasing drift are a productivity tool.
A custom operator shared some very useful tips with me a few
years back. He optimized the small things, such as re-locating the switch to
deflate his suspension airbags after driving onto the trailer, to the platform
beside the cab. He’d deflate while descending the steps, and by the time the tie-down
straps were thrown across, the unit was ready to be cinched down. No waiting.
He also opted for a slightly wider aftermarket boom so he had an even number of
spray passes per quarter, saving another 2 minutes or so per field.
The same operator made me aware of the importance of knowing
exactly how much spray is in the tank at any one time. The majority of spray
monitors are simply not accurate enough. A factory sprayer can count down from
a full tank using its flow meter, but that requires two things to be accurate,
the filled amount (entered by the operator, usually from a sight gauge) and the
flow meter itself. Point is, when we fill the last load of a field, we don’t
want too much left over, but we’d still rather not run out. By using the
AccuVolume from Simon Innovations, he was able to fill accurately and he was
also able to exactly monitor his liquid usage. If he had two passes left, and
knew he needed exactly 150 gallons (also considering when his pump drew air),
he could monitor that and make small adjustments to the application rate, if
necessary, to get there. It’s a big deal because contending with a larger
remainder is wasteful and takes time to deal with. The AccuVolume also helps
make multiple small volume batch cleaning more accurate, and therefore easier.
The AccuVolume measures your tank contents, to the nearest gallon, regardless of slope position. It’s a time saver.
A small addition to the tender truck such as an electric
hose reel or a swing arm that carries, say 20’ of hose, helps deal with the
weight of a full 3” line. Or an air-line at the pump end can be used to blow
the remaining water into the tank. Time, and mess, are saved. Still pumping
product? Induction using a venturi is much faster.
An electric hose reel makes handling 3″ plumbing manageable.
Preventing problems is probably a better use of time than
dealing with them. Take tank mixes, for example. With more products in the
tank, and adjuvants such as conditioners, fertilizers, or low-drift products
making their way in, anticipating mixing problems may require a jar test. Get
the tools, and learn how to do them. It’s important to use the actual tended
water in these tests, at the temperature it will be, because that, and water
quality such as hardness and bicarbonates, can affect mixing. And don’t
over-agitate, as that can create its own problems, especially as the tank runs
down.
Consider a hot tank. If extra labour is available, it removes a lot of time pressure for mixing dry, or multiple products. At filling time, simply pump it over and go.
A hot tank gives you more time to mix properly, and makes transfers faster. (Some additional labour required).
Consider improvements in the plumbing to save time. The new Hypro Express End Cap features a ball valve for flushing (existing Express End Caps can be retrofitted), and this valve can soon be fitted with the ProStop E (electric) valve. Flushing can then be done from the cab, saving time and mess. It’s a small change, but it brings joy.
A new valve addition is available for the Express End Cap. Manual (shown) or electric available.
The importance of time on a spray day can also be viewed economically. Let’s say a large area needs to be sprayed today, and the weather forecast calls for rain overnight. The rain will stop spraying for 5 days. What is the yield potential lost in those five days if weed or disease pressure is high? If 100 acres don’t get treated, what is the lost revenue? (for example, if 3 bpa is lost, at $6/b, that’s $18/acre or $1,800.) That’s what that hour is worth. Tell your boss.
Getting more done means getting more done on time. Evaluate your habits and technologies on that basis.
