Glossary
Pan Test (Pattern Test)
A field calibration where collection pans laid across a drone’s spread are weighed after a pass to map the deposition pattern and set the effective swath so the application comes up even, not striped.
Definition
A pan test (or pattern test) is the method that turns a spreader’s spec-sheet swath into a real, even application. A line of collection pans (or trays) is laid out across the full throw width of the drone’s spread. The drone flies a single pass over the line at the planned rate and release height. Each pan is then weighed to map how much product landed where — the deposition curve, which is always heaviest in the centre and tapers at the edges. From that curve you find where the pattern tapers off and set the effective swath: the narrower width you advance between passes so the tapering edges of neighbouring passes overlap and sum to an even total rate. The evenness is often expressed as a coefficient of variation (CV) — a lower CV means a more uniform spread. Because granule size, density, humidity, rate, and release height all change the pattern, the pan test is re-run whenever any of those change rather than assumed from another product.
In an Alberta Context
On Alberta’s open, windy fields the real deposition pattern drifts away from the brochure swath figure, so a pan test (or a known calibration for the specific granular product) is what keeps a drone spread even across a quarter. Striping from an over-wide swath shows up clearly at green-up and is expensive to explain to a grower after the fact. The pan test is a calibration for granular spreading — fertilizer and cover-crop or forage seed — which is the legal drone service in Canada today; it is not a pesticide-application method. Drone pesticide application (liquid spray or granular bait) is a separate matter, now under a narrow interim pathway following PMRA’s June 2026 Letter of No Objection.
Why It Matters
The pan test is the discipline that separates a credible custom operator from someone who just bought a drone. It is the single calibration that most determines whether a spread looks professional or shows tramline striping, and it produces a documented coefficient of variation you can show a grower. Skipping it means trusting a spec-sheet number that does not account for the actual product, rate, height, or wind — which is how even fields turn striped.
Frequently Asked Questions
+How is a pan test done?
Lay a line of collection pans across the full width of the drone’s spread, fly a single pass over them at the planned rate and release height, then weigh the catch in each pan. That gives the deposition curve — heaviest in the centre, tapering at the edges — which you use to set the effective swath so adjacent passes overlap into an even total.
+What is a good CV for a drone spread?
CV (coefficient of variation) measures how uniform the deposition is across the pattern — lower is more even. A pan test produces the CV for the specific product, rate, and height being flown, so it is a measured result rather than a fixed target lifted from another blend. The point of the test is to set a swath that keeps CV low enough to avoid visible striping.
+How often does the pan test need to be redone?
Whenever the product, rate, or release height changes. Granule size, density, and humidity all change how far and how evenly a product throws, so a pan test done for one fertilizer blend does not carry over to a different blend or to seed without re-testing.
+Why not just use the spreader’s spec-sheet swath?
The spec swath is a starting point measured under ideal conditions. Real granule type, rate, release height, and especially Alberta wind shift the actual pattern, so using the full spec width usually leaves under-applied stripes between passes. The pan test sets the swath to the real pattern.