Tag: speed

Increase Sprayer Productivity Without Driving Faster

Timing trumps most things in crop protection. A great spray applied at the wrong time isn’t nearly as valuable as a mediocre spray at the right time. So how do we improve our ability to get things done at the right time?

Often, we try to win races by driving faster. In our last article, we looked at driving speed and concluded that faster speeds can lead to more drift and less uniform deposition. Driving slower can be viewed as a sort of insurance policy: You may not notice the benefits right away, but on days when that extra bit of performance is required, you’re covered.

So how do you get the job done quickly if you can’t drive faster? To answer, we have to look to other opportunities for boosting productivity.

Recently, we used our and tried to capture all the elements of a normal spray operation that affect timeliness. These were:

travel speed
boom width
tank size
water volume
field length
number of headlands
turning speed
fill time

First, we identified a reasonable base condition. For the sprayer, that was a travel speed of 14 mph, a 90’ boom, an 800 gal tank, a 10 gpa water volume, and a 20 minute fill time. Then, we set up a typical field situation, which was spraying a half-mile run on a quarter with two sprayed headlands and a turning speed of 8 mph. Finally, we changed one factor at a time to determine its relative importance.

Before we discuss the results, let’s make it clear that just because changing some of these factors improves productivity doesn’t mean we’re recommending them! For example, adequate water volume remains an important input that improves coverage and permits the use of low-drift sprays. Larger tanks increase compaction and take more power, and so forth.

Here’s what we found:

All productivity values were expressed as acres per engine hour. For this reason, our numbers will be lower than what a typical sprayer monitor reports, most of which calculate acres per spraying hour.

For the base condition, the sprayer spent 15% of its driving time turning, and 37% of its on-field time stationary (i.e. filling or cleaning). For every hour spent on the field, less than half the time (48%) was spent spraying. This resulted in an average productivity of 82 acres/h.

Increasing the spray speed to 18 mph increased average productivity to 93 acres/h, but it also increased the proportion of time spent turning and loading, resulting in just 40% of the field time spent spraying.

Decreasing the loading time from 20 to 10 minutes reduced the proportion of field time spent stationary to 23%, covering 100 acres/h at 14 mph. Surprisingly, this was the productivity-winner, resuling in 62% of on-field time spraying.

We discovered other powerful productivity factors, and chief among them was boom width. A 33% increase in boom width from 90’ to 120’ gave a productivity boost to 94 acres/h, close to the same result as increasing the travel speed to 18 mph earlier. Similar side effects occurred: more time turning, and a greater proportion of time filling, as we saw with faster travel speeds.

Boom width seems to have some room for growth. Many smaller European counties use wider booms than we do in North America, for example. With gps guidance and large fields, we have excellent conditions for their implementation.

Two other factors that had similar effects to fill time were water volume and tank size. Less water and larger tanks increased productivity by decreasing the fill frequency, with effects similar in magnitude to speeding up the fill time. Decreasing the water volume from 10 to 5 gpa increased productivity to 100 acres/h by decreasing the proportion of time the sprayer was stopped from 37% to 23%. Increasing from an 800 to a 1,200 gallon tank increased productivity to 94 acres/h, again by decreasing the proportion of time spent filling to 28%.

Taken together, a sprayer with a 120’ boom, a 1,200 gal tank, applying 10 gpa and filling in 10 min had an average productivity of 132 acres/h. And this was achieved without driving faster than 14 mph. If you can string two quarters together and drive a whole mile before turning, that number rises to 145 acres/h, a surprisingly large 13 acres/h gain.

The perspective of minimizing downtime extends to other tasks, too:

Be more prepared for the job by reviewing the product label in advance, noting the correct mixing order.
Keep extra nozzles, clamps, and nozzle bodies in the cab.
Don’t clean plugged nozzles, replace them.
Use low-drift nozzles so a small increase in wind doesn’t shut you down.
Ensure all the products needed are on the tender truck (e.g. pesticide, adjuvant, tank cleaner, anti-foamer, etc.).
Consider switching to 3” plumbing (pump rates of 300 – 400 gpm are possible).
Make sure your inductor won’t be the limiting factor. For example, product pumps can be awfully slow when the product is cold. It might be worthwhile to explore a venturi system.

Speeding up the fill process is a good idea, but be careful with certain products. Dry materials such as the sulfonyl ureas (e.g. Refine, Express SG, etc.) and some fungicides (e.g. Astound, etc.) require time to hydrate in water so they mix properly. Some operators pre-hydrate these in a smaller tank, while others get an extra tank to pre-mix whole loads and simply transfer them over.

Also think about the time spent cleaning the sprayer. Thoroughness is important, but perhaps there are efficiencies to be gained there as well, like never letting a sprayer sit after spraying. We’ve written about continuous rinsing, for example, to improve cleaning speed and effectiveness.

So, the quicker we can spray, while ensuring a quality job, the more effective our crop protection practices will be. We encourage you to use our to determine your best configuration.

Got a productivity tips to share? Let us know! And remember: In spraying, the race is won in the pits.

Factor	Base	Drive Faster	Fill Faster	Spray Wider	Less Water	Bigger Tank	New Sprayer
Travel Speed	14 mph	18 mph	14 mph	14 mph	14 mph	14 mph	14 mph
Fill time	20 min	20 min	10 min	20 min	20 min	20 min	10 min
Boom Width	90 ft	90 ft	90 ft	120 ft	90 ft	90 ft	120 ft
Water Volume	10 gpa	10 gpa	10 gpa	10 gpa	5 gpa	10 gpa	10 gpa
Tank Size	800 gal	800 gal	800 gal	800 gal	800 gal	1200 gal	1200 gal
Field Length	0.5 mile	0.5 mile	0.5 mile	0.5 mile	0.5 mile	0.5 mile	0.5 mile

Time Turning	15%	19%	15%	20%	15%	15%	20%
Time Loading	37%	42%	23%	42%	23%	28%	19%
Time Spraying	48%	39%	62%	38%	62%	57%	61%
Acres/h	82	93	100	94	100	94	132

To work with the productivity calculator, click here.

August 20, 2026

How Higher Speeds Affect Drone Swath Width

Speed Study

Swath width is a fundamental parameter in spray drone mission planning. It facilitates the uniform application of broadacre pesticides at the target rate. Pilots adjust the swath width via operational settings such as droplet size, flight speed and altitude to produce the most effective and efficient application.

Rapid advances in drone design, however, may warrant a re-evaluation of how operational settings affect swath width. For example, the most recent generation of drones are now capable of speeds up to 20 m/s (72 km/h), which is twice that of the previous generation.

In late 2025 we conducted a series of comparative herbicide applications using the DJI Agras T50 and T100. For both drones, swath width increased with speed up to ~10 m/s, as expected. However, between ~10 m/s and 18.5 m/s, swath width from the T100 did not seem to increase further. Similar observations have been reported by researchers at AgroEfetiva (São Paulo, Brazil; personal communication).

These results suggest that the relationship between speed and swath width is positive and direct at lower speeds, but reaches a saturation point beyond which any further increase in speed no longer affects swath width. This is an asymptotic relationship. To test this hypothesis, we conducted a deposition study where swath width was measured at flight speeds that increased incrementally from 8 m/s to 20 m/s.

Configuration Study

The standard T100 configuration uses two rotary atomizers (“sprinkler” nozzles; LX07550SX) with a reported maximum combined flow rate of 30 L/min. The alternate orchard configuration incorporates a boom that supports two additional “mister” nozzles (LX09550SX), increasing the reported maximum flow rate to 40 L/min.

To improve productivity in broadacre applications, some operators have adopted a hybrid configuration. In this setup, the orchard boom is retained, but the reputedly drift-prone mister nozzles are replaced with a second set of sprinklers. This approach is intended to achieve a higher flow rate than the standard two nozzle configuration while maintaining a larger mean droplet size.

A secondary objective of this study was to compare the Hybrid configuration with the Orchard configuration (Figure 1).

Figure 1 – Left: DJI Sprinkler Nozzle (LX07550SX). Four such nozzles comprised the “Hybrid” configuration. Right: DJI Mister nozzle (LX09550SX). Four such nozzles comprised the “Orchard” configuration.

Materials and Methods

Location and Layout

The study was conducted at Ontario’s Simcoe Research Station on May 12, 2026. The site (42.857414, -80.271759) was a flat, recently tilled sand/loam field with no vegetation present. A DJI Agris T100 drone was used to perform the spray applications, supported by the D-RTK 3 relay station and flown on full auto.

The spray mix was 0.2% v/v Super Signal Blue (Precision Laboratories) and 0.125% v/v Activate Plus NIS (Winfield United) in municipal water, pre-mixed to ensure consistency. A volume of 40 L – 60 L was maintained throughout the trial to minimize the effect of a changing payload.

The sampler was a flat, horizontal, continuous bond paper strip measuring 7.5 cm wide and 30 m long (secured in Speed Tracks™, Application Insight LLC). The sampler was oriented perpendicular to the prevailing wind, with the intention of flying the drone with a headwind across the 15 m mark (the centre) (Figure 2). Test passes determined that the T100 required 210 m to reach 20 m/s while half-full.

Figure 2 – T100 spraying indicator dye across the 30 m continuous sampler.

Before the swathing runs began, the prevailing wind shifted direction slightly. It was decided to fly the drone 5 m upwind (at the 20 m mark along the 30 m sampler) to ensure any downwind displacement was captured on the sampler (Figure 3).

Figure 3 – Trial layout and prevailing wind conditions.

Drone Settings and Swathing Order

The primary objective of the study was to explore the effect of flight speed on swath width. Speed was increased from 8 m/s to the maximum 20 m/s by 2 m/s increments. Trial and error with the controller indicated that we could achieve these speeds by balancing an application volume of 30 L/ha and a programmed swath width of 7 m.

Altitude was set to 4 m which is lower than the 5 m minimum recommended by DJI for high-speed flight. This was a compromise above the preferred 3.5 m altitude we have historically used with the T50. It was felt that higher altitudes would create unacceptable potential for swath displacement.

Rotary atomizer design is not standardized, and as a result, the droplet size selected on the controller did not necessarily produce the desired results. The Hybrid configuration was programmed to emit 350 µm droplets, selected as a compromise between drift mitigation and coverage potential. To offset the Mister nozzles’ reputation for producing a finer spray, the Orchard configuration was set to the maximum 500 µm. Operations settings are noted in Table 1.

Configuration	Nozzle	Droplet size (µm)	Speed (m/s)	Altitude (m)	Programmed Swath Width (m)	Application Volume (L/ha)
Hybrid	4 Sprinklers	350	8, 10, 12, 14, 16, 18, 20	4	7	30
Orchard	2 Misters, 2 Sprinklers	500	8, 10, 12, 14, 16, 18, 20	4	7	30

Table 1 – Operational settings for trials.

Three repetitions of seven speeds were flown for each configuration. Anticipating an increase in temperature and wind speed throughout the day, it was decided move through all seven speeds (a single repetition) before resetting and doing so two more times. The intent was to preclude confounding weather effects. Ideally, we should have alternated between configurations as well, but this proved impractical. As a result, we flew the Hybrid configuration first and the Orchard configuration last.

Weather

Weather data was collected using a Kestrel 3550AG weather meter (Kestrel Instruments) in a vane mount positioned 2.5 m above ground. Temperature and relative humidity were comparable throughout the ~3 hours of data collection, but as anticipated, wind speed was higher for the later Orchard configuration passes.

As previously indicated, wind direction shifted from an ideal headwind situation just before trials began, and was somewhat changeable, but the average wind direction for the two configurations was comparable (Figure 4 and Table 2).

Figure 4 – Weather conditions recorded at roughly 10-minute intervals, corresponding to the drone passing over the sampler.

Time	Configuration Flown	Average Temperature (°C)	Average Relative Humidity (%)	Average Wind Speed (km/h ± SD)	Average Direction (° ± SD)
11:55 am – 1:16 pm	Hybrid	11.7	59.9	8.4 ± 3.5	323 ± 46
1:43 pm – 2:52 pm	Orchard	12.9	51.6	11.9 ± 2.5	316 ± 48

Table 2 – Average weather conditions for the Hybrid configuration passes and for the Orchard configuration passes.

Collector analysis

Bond paper digitization

Bond papers were scanned using a Swath Gobbler™ (Application Insight LLC). The software measured deposition as both percent area covered (% area) and deposit density (deposits/cm²) every 100 mm, with a thresholded Hue of 23-280, a Saturation of 5-120 and a Value of 156-255.

Effective swath width calculation

The large data set produced by each pass was reduced in size by averaging the deposition for every 50 cm. This data was entered into our Excel-based swath width calculator, which assumes a racetrack pattern and sums deposits from adjacent swaths. The resulting swath width for each pass was the maximum width that minimized over- and under-dosing as well as the coefficient of variation (CV).

Analysis

The average swath width derived from deposit density data was wider than that derived from percent area covered (Table 3).

Table 3 – Group means and standard deviation for average swath widths derived from deposit density data and percent coverage data. The average CV was between 29 and 32%.

A two-way ANOVA (Analysis of Variance; α = 0.05) was performed to determine any significant effect of speed or configuration on swath width (Table 4). Flight speed had no significant effect on swath width, no matter how it was derived (% area covered or deposit density), for either configuration (Hybrid or Orchard). However, the average swath width derived from deposit density was significantly wider for the Orchard configuration compared to the Hybrid and presented higher variability.

Table 4 – Results of two-way ANOVA, exploring interactions between speed, swath width and configuration (95% confidence interval).

Orchard configuration was prone to displacement in a side wind. Shifting the flight path 5 m upwind improved the downwind capture, but for some flights it did trim a small portion of the upwind deposition. Deposit density gives greater resolution and exposes more variability than percent area covered. Figure 5 shows the average deposition by speed based on deposit density. Figure 6 shows the average deposition by speed based on percent area covered.

Figure 5 – Average deposition by speed based on deposit density. Arrow indicates flight path.

Figure 6 – Average deposition by speed based on percent area covered. Arrow indicates flight path.

Figure 7 shows the average deposition by configuration based on deposit density. Figure 8 shows the average deposition by configuration, based on percent area covered. Based on deposit density, there were 55% more deposits on the downwind side of the sampler for Orchard configuration set to set to 500 microns compared to the Modified configuration set to 350 microns.

Figure 6 – Average deposition by configuration based on deposit density. Arrow indicates flight path.

Figure 8 – Average deposition by configuration based on percent area covered. Arrow indicates flight path.

The average swath widths calculated from deposit density (Figure 9) and percent area covered (Figure 10) are shown with standard deviation. While it appears the swath width is less around 14 m/s, it is statistically insignificant and the response to speed is essentially flat. As with prior studies, swath widths calculated from deposit density are larger than those calculated from percent area covered.

Figure 9 – Average swath widths for each speed, derived from deposit density data. SD shown. n=3 for each speed, while n=2 for Hybrid configuration at 12 m/s and 14 m/s.

Figure 10 – Average swath widths for each speed, derived from percent coverage data. SD shown. n=3 for each speed, while n=2 for Hybrid configuration at 12 m/s and 14 m/s.

Observations

Previous studies demonstrated a direct and positive relationship between drone speed and swath width up to 8-10 m/s. Here, we see no further response after ~8 m/s. This supports the hypothesis that rotary-wing drone speed and swath width share an asymptotic relationship that inflects at ~8-10 m/s. Variability makes it difficult to determine an exact value.

Despite increasing the programmed droplet size to the maximum 500 microns for the Orchard condition, there was 55% more downwind deposition compared to the Hybrid condition, which was set to 350 microns. This supports the claim that the Mister nozzle produces a span of droplet sizes that include far more fines than the Sprinkler nozzle, and underpins the need for a better understanding of the spray quality produced by rotary atomizers.

Spraying at high speeds is not an advisable practice. While swath width is no longer affected after ~8 m/s, there are other considerations. Note that it required 200 m for the drone to reach the highest speed, and in a related study we have seen swath width taper during initial acceleration and final deceleration, leaving gaps in coverage.

Further, the minimum 5 m altitude advised by DJI ensures a safe margin for the drone to respond to obstacles and topography during high speed flight, but is not conducive to spraying. The author is aware of a situation where flying the T100 at 4 m altitude and 18 m/s over a canola field with rolling hills caused it to perform an emergency landing.

An ideal speed is one that maintains the most consistent swath width at a reasonable altitude.

Thanks to Drone Spray Canada and Bayer Canada for in kind and financial support, and thanks to Cesar Cappa, OMAFA horticulture weed specialist for his participation in the study.

June 13, 2026

Gear up – Throttle down
In 1977, David Shelton and Kenneth Von Bargen (University of Nebraska) published an article called “10-1977 CC279 Gear Up – Throttle Down”. It described the merits of reducing tractor rpm’s for trailed implements that didn’t need 540 rpm to operate. In 2001 (republished in 2009), Robert Grisso (Extension Engineer with Virginia Cooperative Extension) described the same fuel-saving practice. Again, it was noted that many PTO-driven farm implements don’t need full tractor power, so why waste the fuel? He tested shifting to a higher tractor gear and slowing engine speed to maintain the desired ground speed. 700 diesel tractors were tested, and as long as the equipment could operate at a lower PTO speed and the tractor itself didn’t lug (i.e. overload), as much as 40% of the diesel was saved.
How this applies to Airblast
For airblast operators with PTO-driven sprayers and positive-displacement pumps, this has potential for reducing air energy. Gearing up and throttling down (GUTD) sees the operator reducing the PTO speed from 540 rpm to somewhere between 350-375 rpms, which not only saves fuel but more importantly slows the fan speed. This may be an option when air energy from the sprayer, even at higher travel speeds and a low fan gear, still overblows the target canopy.
Some airblast sprayers, like this one, feature fan blades with manually-adjustable pitch to increase or lower air volume and speed. It’s often a pain to try to adjust them, and most operators only try it once.
A good time to try this out is early in the spraying season when (most) canopies are dormant and at their most sparse. For example, when applying dormant sprays in apple orchards, look to see if the wood on the sprayer-side gets wet, but does not creep around the sides. This suggests that the air, and much of it’s droplet payload, are being deflected. When the air speed is slowed, it will become more diffuse and turbulent on target surfaces, and this turbulence helps more droplets deposit in a panoramic fashion within (not past) the target canopy. Look to see if the wood is wet >50% around the circumference of the branches. You’ll get the rest when you spray form the other side.
Limitations
GUTD is not always appropriate. It requires airblast sprayers with PTO-driven positive displacement pumps (e.g. diaphragm). Airblast sprayers with centrifugal pumps would experience a drop in operating pressure and would have to be re-nozzled. Further, the pump must have sufficient surplus capacity to maintain pressure at low rpms.
GUTD is not intended for air-shear sprayers that employ twin-fluid nozzles because dropping air speed below a certain threshold may compromise spray quality; the air needs to be fast enough to create and direct spray droplets
The tractor must have sufficient horsepower (more than 25% in excess of minimally-required capacity) to permit the reduction in engine torque. This is especially important if the operator is on hilly terrain. If the tractor begins to lug (e.g. black smoke, sluggish response, strange sounds) you’ll be in trouble.
Observations
We first experimented with GUTD in 2013. We noticed how much quieter the sprayer was, and the fuel consumption was certainly reduced. One grower-cooperator switched to a GUTD spray strategy mid-way through their dormant oil application in pears. We saw the trees immediately began to drip. Panoramic coverage was improved significantly; once the operator passed down the other side of the target, capillary action and surface tension helped to give near-complete coverage.
However, in one instance, the operator was already applying a low spray volume per hectare using air induction nozzles and their lowest fan gear. By further slowing fan speed using GUTD, coverage at the top of his cherry trees was compromised.
In short, GUTD can work under the right circumstances. If you want to try it, use water-sensitive paper to establish a base-line with your current practice, and then evaluate coverage after you change your sprayer settings.
May 18, 2022
How to Size a Nozzle for Pulse Width Modulation (PWM)
PWM is gaining popularity, and there is an ever-increasing number of first-time users that need to make nozzle selections for their system. We’ve written about it here, here, and here.
Recall the PWM replaces spray pressure with Duty Cycle (DC) of a pulsing solenoid as the primary means of controlling nozzle flow. The solenoid shuts off the flow to the nozzle intermittently, between 10 and 100 times per second depending on the system. The Duty Cycle is defined as the proportion of time that the solenoid is open, and for low-frequency systems, DC is more or less linearly related to flow rate.
The first rule of PWM nozzle selection is to understand that under average travel speeds, we’d like to see the duty cycle of the system at between 60 and 80%. This means that the nozzle solenoid is open about 2/3 of the time. This value also describes the flow rate as a proportion of the full capacity that nozzle.
The reason for this 2/3 duty cycle rule is to enable four key features of PWM:
1. It’s ideal for turn compensation, allowing the outer nozzles to increase their flow 20 to 40%, and the inner nozzles to decrease flow about three-fold, in accordance with boom speed.
2. It allows speed flexibility, providing some additional speed, but more importantly, reduced speeds should conditions require it, without a change in spray pressure.
3. It compensates for pressure changes so that spray quality can be adjusted without requiring a speed change. Less pressure reduces nozzle flow, and increasing DC recoups accordingly.
4. It allows for customized higher flows of certain nozzles, perhaps behind wheels, to address reduced deposition in their aerodynamic wake (available on some PWM systems).
The best tool for selecting the right nozzle size is Wilger’s Tip Wizard. This site asks for your desired average speed ( although it calls this “Max Sprayer Speed”), and reports the expected DC for a host of nozzle size solutions and pressures. It also reports maximum and minimum travel speeds and other useful information such as spray quality.
Fig 1: The Tip Wizard is a useful tool for sizing nozzles on any PWM system. Sizing information applies to any nozzle. Spray quality information is for Wilger ComboJet nozzles only.
Although intended for Wilger nozzles, the site’s sizing feature works for any nozzle brand. It asks the user which PWM system they have for the purpose of calculating the documented pressure drop across the solenoid.
Fig 2: Tip Wizard results for the Wilger SR11006 tip at 10 gpa and 15 mph. Look for a solution that provides 60 to 80% Duty Cycle (DC).
If you don’t have access to the site, a basic calibration chart can still work with a simple trick. Recall that we use the top row to identify the desired water volume, and the table’s interior values are speeds, as described here.
Below are two solutions for someone wanting to apply 10 gpa at 15 mph without PWM. The correct choice depends on the required pressure to produce the needed spray quality.
Fig 3: A conventional calibration chart, solving a 10 gpa application for 15 mph.
If you want to apply the same 10 US gpa using PWM, simply solve for a larger volume that offers the right DC. For example, choosing 13 gpa will over-apply by 3 gpa, or 30%. The PWM system adjusts by running at 100-30=70% DC. If the chart doesn’t offer 13 gpa, go nearby, to 14 gpa, as we did below:
Fig 4: By pretending to require 14 gpa instead of the actual 10 gpa, the conventional calibration chart is tricked into solving for a nozzle size that will work with PWM at 60% Duty Cycle.
Now solve for the same target speed, 15 mph. The solution will run at 60% DC. Again, there is more than one choice, and that will depend on the spray pressure needed.
Fig 5: Two possible solutions for achieving 10 gpa at 10 mph. An 06 nozzle at intermediate pressure or an 08 nozzle at low pressure.
We’ve developed a template, in US or metric units, that can be customized for any water volume. Here is the same chart with 13 gpa added:
Fig 6: A conventional calibration chart with the 13 mph speed added.
The best solution for 10 gpa at 15 mph is the 06 size nozzle at 50 psi. This is not engraved in stone. One of the nice things about PWM is that it has inherent flexibility. Make the nozzle pressure a priority to get the correct spray quality. It really doesn’t matter whether the resulting DC is 65 or 80%, the system will still work well. Simply avoid extremes that take you below 50% or above 90%, they will limit the system’s capabilities.
The worksheet can be downloaded below:
Application-Chart-Template-2-PWM Download
It can handle any water volume or nozzle spacing by filling in the blue cells. Two additional worksheets in the file automate the process, simply enter the desired application volume, travel speed, and nozzle spacing (yellow cells), and the solution that offers the optimal duty cycle range will be highlighted in light green.
February 21, 2022
Exploding Sprayer Myths (ep.4): Speed Spraying
All set for Star Wars VII
With due respect to Mickey and Mr. Lucas, and the massive hype surrounding Star Wars Episode VII, we felt we should jump on the bandwagon. Here’s episode IV in our series of short, educational and irreverent videos made with Real Agriculture.
If there’s a single take-home message in this episode it’s this:
…may the force be with you – always.
December 20, 2019