Tag: productivity

Putting a Number on Pesticide Waste
Waste (noun): an act or instance of using or expending something to no purpose.
In agriculture, environment and economy are intertwined. Producers strive to obtain the maximum return on their inputs. They study incremental returns and avoid applying more inputs than necessary, especially if conditions don’t warrant it. The financial incentive is powerful, and waste is a four-letter word. This applies to seed, fertilizer, and pesticide. Pesticide labels identify the rate needed to obtain the desired result, and there is no incentive to over-apply. In fact, it’s illegal.
But there are plenty of other places where applications incur waste. As with time efficiency, it’s a good idea to identify where this waste occurs, and the only tool needed is a sharp pencil.
When might we incur waste in the spray application process?
- Mixing more than we need because we don’t trust the flow meter or the tank gauge entirely, or don’t know the exact field size.
- Priming the boom before the first swath.
- Overlapping due to curvy terrain and coarse sectional control.
- Spray drift away from the intended swath.
How big are the losses?
Let’s say we have a clean sprayer and need to spray 160 acres before moving to a new crop and product. We plan to apply 10 gallons per acre and have a 1,200 gallon tank with a 120 foot boom. That means we need 1,600 gallons of spray mix in total.
Once we’re at the field we prime the boom. Each sprayer is different, but depending on operator experience, 30 to 50 gallons are usually needed to push product from the tank to the last nozzle. Only part of that is lost to the ground, as boom sections can be shut off as soon as product has reached every nozzle of that section. We’re assuming 0.2 gallons per foot of boom is lost.
Spraying itself is relatively straightforward. Swath and sectional control handle the overlaps, but in less ideal terrain, double application is known to account for 4 to 5% of the area to reach non-square parts of the field. This is even more likely when the outer section is 10’ or more. Early turn-on of the boom prior to leaving the headland, to allow boom to reach operating pressure, adds to this.
Air-activated shutoff for individual nozzles reduces section size at a reasonable cost.
With an average nozzle, we can expect about 2% of the product to airborne drift. Most airborne won’t return to the ground within the field borders, so it’s a complete loss.
Most of the spray that travels more than 5 m after leaving boom stays airborne and should be considered a total loss from the field.
As we finish, the pump will draw air before the tank is empty due to sloshing or foaming, and a 50 to 60 gallon remainder may not be unusual. This simulation has assumed 5% of tank volume remains.
We also need to purge spray from the boom at cleanout, consuming approximately 0.4 gallons per foot of boom. This occurs after the field is completely sprayed and is therefore considered waste.
So how does this add up? The following table shows the approximate losses associated with five setups.
Table 1: Spray mix losses during a sprayer operation. Setup 1 = baseline, Setup 2 = low application volume, Setup 3 = baseline with recirculating boom, tank level monitor, and low-drift nozzles, Setup 4 = large area between cleaning, Setup 5 = large area with recirculating boom, tank level monitor, and low-drift nozzles.
In the first scenario, we spray just 160 acres at 10 gallons per acre. Priming the boom with 0.4 gallons per foot (allowing for all associated feed lines) consumes 48 gallons, but only wastes half of that, or 1.5% of the total volume needed for the field.
Four percent overlap consumes another 64 gallons.
If we have 5% of the tank volume left over, that’s 60 gallons. That amount is so small it doesn’t even register on the sight gauge but nonetheless it represents another 4% of the total sprayed amount.
Upon cleaning the boom, we need to push the spray mix out of all the plumbing after the pump, as it has nowhere else to go. At an assumed 0.4 gallons per foot, that’s another 48 gallons or 3%.
If we add to that a conservative 2% drift loss, it sums to a surprising 14% of the total spray volume. For those that use lower water volumes (the second scenario), the volumetric losses are slightly less, but their proportion is higher, now accounting for 23% (!) of the total spray mix.
In the third scenario, let’s assume we use a recirculating boom that returns the initial prime volume to the tank, eliminating any waste. We’ll also upgrade to individual nozzle sectional control, reducing overlap to 1%. And, since we want to know exactly what’s left in the tank, let’s invest in an AccuVolume system to precisely monitor tank volume. This allows us to make small rate adjustments up or down to be sure as much of the mixed product goes onto the sprayed swath as possible.
Recirculating booms allows the spray mix to pass through entire length of boom without being sprayed, saving waste during priming and allowing waste-free boom rinses.
When the sump begins to empty, we can introduce some water from the clean water tank to push the last of the mix to the boom (a continuous rinse system makes this easy).
An AccuVolume sensor shows the exact volume left in the tank at any slope position and with 1 gallon resolution, allowing greater accuracy when filling and emptying.
We’ll assume our sump waste is now reduced to 12 gallons. We still need to dispose of the content of the boom somehow, so the recirculating boom offers no saving there. But let’s also add better low-drift nozzles to reduce drift by 50% (now 1% total volume). Total loss is now just 6%.
Low-drift nozzles such as this AirMix (Agrotop) SoftDrop reduce airborne drift by 50 to 90%.
The last two rows in the table repeat the first and third scenarios for a larger sprayed area (1000 acres) before a tank cleaning is needed. This doesn’t change the magnitude of the volumetric loss, but reduces its proportion. Percent loss is down by a factor of two from the 160 acre interval, to 3 to 7%.
Experienced operators might cheat the system a bit by mixing the required pesticide with some extra water to make up for the plumbing waste. Doing so prevents extra pesticide from being consumed, but it doesn’t reduce the inherent inefficiency.
Lessons
This exercise suggests that waste from spraying is probably higher than we assumed. If we average the scenarios, there is 10 to 15% waste. At, say, $200,000 spent on pesticide for a single spraying season, that’s $20 – $30,000 worth of product and water hauled that ends up where it doesn’t belong. Beyond the time and money, there can also be environmental consequences depending on how that waste is treated.
There are some things that can be done.
- Know the exact area of the field to be sprayed.
- Study your sprayer plumbing and consider improvements such as recirculating booms and continuous cleanout.
- Improve monitoring of tank content to allow lower remainders.
- Consider individual nozzle shutoff to improve sectional control. These are part of Pulse Width Modulation (PWM) systems, but can also be achieved with less expensive valves.
- Plan spray operations to minimize the amount of product changeovers.
- Consider direct injection.
The return on investment for plumbing improvements can be high and result in considerable future savings over the life of the sprayer. It’s worth thinking about.
Spray Waste Worksheet Download
January 18, 2021
Don’t try this tempting shortcut
There’s a call that I’ve been getting for 20 years now. It came again this week. Someone has a twincap with two small air-induced tips, and they’re applying herbicides and fungicides with low water volumes, often 5 gpa, sometimes less. They call because they want to know how much wind they can spray in. Is 30 km/h OK? They want my blessing.
I don’t need to hear much more. Some nozzles are sold entirely on the premise that they provide superior coverage – more droplets per square inch – and that this improved coverage permits the reduction of water volumes. Furthermore, the claim goes, when water is reduced, the spray concentration increases and the whole darn package just works a lot faster and better.
This line of thinking is as old as spraying itself. Applicators seek pesticide performance as well as productivity, and this approach gives them both. The proponents are well aware of their customers’ desires, and sell into it. “Use these tips and cut back on water. Any more than this just runs off anyways. You’ll get better coverage and better performance, get more spraying done.” It’s a convincing argument. Get an edge on your neighbour, the person who’s not in on the secret and is wasting time and water.
Why don’t I embrace it? There are a few reasons.
First, it doesn’t tell the whole story. Invariably it involves a twin nozzle setup. Use two nozzles, get more droplets, right? If that were true, believe me, I’d be advocating for quintuples.
Fact is that the only factors that change droplet numbers are droplet size (spray quality) and water volume. Want more droplets at the same water volume? Make the spray finer. Want to keep spray quality and add droplets? Add water (not nozzles).
The easiest way to improve coverage at the same volume is to use a finer nozzle, or to increase spray pressure. Depending on how far you go, you could make the spray finer and cut water, and still have more droplets per square inch.
The hardest way to improve coverage is to purchase a twincap and buy two nozzles, each of them half the size. True, within any given nozzle type, smaller sized tips usually generate finer sprays. But why bother with two tips? They’re more expensive and plug more.
If someone asks me how to improve coverage without changing water volume, I usually tell them to speed up a few mph. The rate controller will increase pressure and the spray gets finer. If speeding up is not possible, get one size smaller nozzle and run at higher pressure, same speed. Or keep nozzle and speed, and add some gpa, pressure will go up. It’s that easy. No twins necessary.
Second, the twin nozzle/low volume approach exaggerates the value of the twin nozzle for herbicides. With small plants and relatively open canopies in the early season, plus our high booms and travel speeds, the twin tips are not adding a lot, if anything at all, to coverage. It remains a sum of droplet size and water volume, the angle is not important at this stage. Deposit is by turbulence and wind, most of the time.
Third, low volume believers ignore a few potential problems. Drift is a big one. Low volume, fine spray operators are surrounded by nervous neighbours. They have fewer hours per day during which drift is acceptably low. And they definitely should not be on the field when wind is at 30 km/h. Basically, they’re a bit uncomfortable (at least they should be) and get less done per day.
Another potential problem is evaporation. Most sprays, even when applied at lower volumes, are still 90% or more water. The same volume of water evaporates much quicker when atomized into smaller droplets. This has two main downsides: On their way to the canopy, small droplets evaporate and become even more drift prone, and may not impact at all. Those that impact evaporate shortly thereafter. Research has shown that pesticide uptake is better from wet than dry deposits.
When Delta T (dry bulb minus wet bulb temperature) is high, evaporation can be so strong that it reduces pesticide performance or causes solvent burn. Fine sprays make it worse.
I also hear about the use of oily adjuvants to control evaporation from small droplets. This could be even more dangerous. Small droplets drift, and evaporation to dryness is actually helpful in reducing the impact of that drift. How? It makes the small droplets disappear, with their remnants dispersing into the turbulent atmosphere. With oily adjuvants, the small droplets stick around and stay potent and their drift damage is much worse.
Lastly, the practice is possibly off label. Water volume and spray quality label statements are designed to offer good performance and acceptable drift risk. While that part of the label is often a bit dated, it does provide better support from the manufacturer should something go wrong.
If you’re spraying under hot, dry and windy conditions, the low volume, fine spray approach is irresponsible. Use sufficient water (7 to 12 gpa) to allow low-drift sprays, at least Coarse to Very Coarse, in some case, even coarser.
Agronomists provide the best possible information for their clients, based on scientific evidence and experience and in accordance with their professional code of ethics. Sometimes the news we deliver aren’t what the customer wants to hear. But we have to represent the interests of all of us, collectively. I find that pretty important.
June 12, 2020
Productivity Calculator
Want to figure out how your sprayer configuration affects your productivity? Try out that tells you acres per hour, the amount of productivity lost to turning, cleaning, filling, and transporting. You can test the benefit of faster tendering, bigger tanks, wider booms, /or changing the application volume.
You might be surprised how productive you can be without driving faster.

productivity_calculator v4 Download
Download the app to your phone or laptop where it will run natively. On a phone, use the “Save to Homescreen” feature to create an icon there.
October 16, 2019
Recirculating Booms – Introduction to the Concept
Listen to the audio version of this article here
A lot of people are intimidated by sprayer plumbing. One look at the spaghetti bowl of spray mix and hydraulic hoses and valves, and they walk away. It hasn’t helped that much of it is concealed under the frame and all of it is in the same black colour, so figuring it out on your own is almost impossible.
Belly of a typical sprayer, showing black hydraulic and spray hoses.

Let’s quickly review the basics. In all sprayers, the liquid in the tank is drawn out from the bottom and pressurized by a pump. The pressurized liquid is split into two main paths. One goes to the spray boom to hydraulic atomizers (nozzles). The other goes back to the tank to agitate the liquid and act as a pressure bypass when the booms are off. Bypass throttling changes pressure. That’s it.
Sprayer plumbing diagram (Source: TeeJet).

By the way, has anyone ever thought of some colour-coding or labelling the hoses and valves on a sprayer? We’d definitely appreciate that.
Conventional boom sections
Most North-American sprayers feed the pressurized liquid to the boom, where the flow is subdivided into physical sections that define the various portions of the boom that can spray at any one time. Older sprayers might only have two sections, the left and the right boom. Wide booms now have anywhere from 5 to 13 sections, each about two to four metres wide. Each section has a pressure feed to its middle, and each section terminates at two dead ends, at which we place caps or valves for flushing.
A conventional plumbed boom with two sections. Each section has two terminal ends that require cleaning. Boom can only be flushed or primed by spraying or by opening boom end caps.

Sprayer with nine sections, each controlled by its own valve and each running a dedicated feed hose.

Two partial boom sections, each showing a central feed line and a capped boom end.

Sectional boom end showing 10 cm of capped pipe beyond last nozzle body.

Boom end with valve to facilitate draining and flushing.

Any liquid that enters this type of boom must exit at the nozzle or the boom end. It must be sprayed out or drained. This poses three distinct problems.
- If the boom contains water or a previous spray mix, the boom needs to be primed with the new product before spraying. We need to spray or drain the existing product out.
- If we want to clean the boom or flush it with water, again we need to push the existing liquid out.
- If we have dead spots in the boom section, such as a boom end, we need to take special care to flush those out as well.
These characteristics complicate cleaning, create waste or contamination, and take time.
Recirculating booms
In a recirculating boom, the spray mixture enters the boom at one end and exits at the other, returning to the spray tank. In most cases, the left and right wing each has its own feed and return. Sectional control is achieved via individual valves (air or electric) placed on the nozzle bodies.
There are two main types of recirculating booms on the market.
The first system routes the pressurized mixture into the boom and shuts off the return line during spraying. When the nozzles are shut off for a turn, the return line opens automatically and the boom flow is pushed past the nozzles back to the tank. When the nozzles spray again, the return line closes to pressurize the boom.
Recirculating boom system offered by Pommier. One end of boom is pressurized, the other end is return. Return flows when boom spraying is shut off. Boom can be primed or flushed without spraying.

This is the system used by Pommier, the French aluminum boom manufacturer who first introduced recirculating booms to North America.
Pommier recirculating boom.

Pommier boom showing stainless steel supply and return lines, as well as air-activated shutoff valve on nozzle body.

The second type of system contains a 3-way valve, connected to the return line and the pressure side of the pump. This valve provides the option of either allowing the return line to go back to the tank, as above, or to also allow pumped flow to the return side so that the boom is pressurized at both ends.
Recirculating boom that allows return line to be either pressurized by pump, or return to tank.

Top view of D.O.T. Connect sprayer recirculating boom setup. Lower line is pressurized by pump. Upper line is return. Three-way valve allows return line to either go back to tank, or be pressurized by pump.

Tidy setup of pressure and return lines on D.O.T. Connect system.

This feature may be useful with long booms along which pressure drop is more likely to occur, or when very high flows are required, and was introduced to North America by the Dutch manufacturer Agrifac, about which we wrote here and reprinted Mick Robert’s article from Pro Operator here. A similar system is available from Rogator (starting in 2018) via their C-Series featuring LiquidLogic. It has also been used on the Connect sprayer, developed by Pattison Liquid Systems, for the D.O.T. autonomous platform.
The main advantages of this design are that it provides the option of additional pressure to the spray boom to avoid pressure drop, and to allow any spray mix in the return line to be pushed and sprayed out to the boom for rinsing in the field. This lowers the remaining volume that needs to be diluted.
Agrifac recirculating boom showing return loop at boom end.

Boom end on Rogator Liquid Logic system. Note Hypro Pro-Stop E shutoff valve.

Features
Recirculating booms offer advantages in terms of preventing soil and water contamination and also in terms of simplifying the boom cleaning process. The design provides an opportunity to graduate to a better resolved sectional control as well due to the requirement for individual nozzle shutoff valves.
Due to shorter and less complex lengths of plumbing needed, stainless steel can be used for the return lines which decreases the potential for pesticide residue being adsorbed.
To rinse a boom with product mix still in the tank, simply draw water from the on-board clean water tank and push it to the boom without activating any nozzle bodies. The mix in the boom is returned to the tank and replaced with water, nothing is sprayed or drained. The tank contents may become slightly diluted depending on the duration of the rinse.
To rinse the tank as part of the sprayer cleanout, first spray the tank empty. Then introduce clean water into the product tank via the wash-down nozzles and spray that out. As always, either use several batches of small clean water volumes, or a continuous rinse system, to dilute the remainder most effectively. There may be additional volume to dilute from the return lines compared to a conventional system, depending on the type of recirculating system is used. However, boom ends no longer exist and this saves effort and ensures a more thorough rinsing.
To prime a boom that contains water, simply open the return lines back to the tank and allow the new mix to flow through the boom. Again, some dilution of the tank will occur due to the water in the boom.
The value of spray-free rinsing and priming adds up. Each prime, for example, consumes about 30 US gallons before the spray reaches the last nozzle of the longest section. Much of that product ends up on the ground, probably while the sprayer is stationary, and probably in a similar place on the field year after year.
Since a recirculating boom requires a powered individual nozzle shutoff, this adds some cost. However, the opportunity of improved sectional control via virtual sections is significant (most monitors offer 16 virtual sections that can be configured). Well-configured virtual sections can save several percent from overlaps.
Recirculating booms remove many of the contamination problems associated with conventional plumbed sections. They save time, money, and reduce environmental impact. We think they should be offered on sprayers.
Here’s a link to a nice article on recirculating booms written by Spencer Myers for the Manitoba Co-operator. A video that goes with the article can be found here.
January 22, 2019
Techniques to Improve Spray Productivity
Click here for an audio version of this article
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.
Evaluate your spray productivity with our
January 19, 2019