Broadcast spreader enters 21st century

New disc design | Kuhn machine called a precision broadcast fertilizer spreader

It seems odd that sales of broadcast fertilizer spreaders increased at the same time that precision farming became popular in North America.

Spreaders seem contrary to what was assumed to be the mainstream trend, but interest in the equipment is so strong that Kuhn has introduced a new model it has dubbed a precision broadcast fertilizer spreader.

The Kuhn AXIS 50.1 H-EMC is hydraulically driven, with enough force to sprinkle an accurate, uniform swath of granular fertilizer up to 164 feet. The electronic mass control takes a reading once every second, allowing the distribution disc on each side to adjust independently for fertilizer density, slope, prescription map instructions and GPS location signals.

Ryan Pearcy, product manager for Kuhn, said there are many logical reasons for the renewed interest in broadcast spreaders.

“We see a definite trend back to granular fertilizer. Timing of application is one of the first things farmers tell us about,” Pearcy said.

“Another reason is the ability to do multiple passes to match the needs of the crop. The risky economics of anhydrous ammonia is another huge factor. Farmers hate losing their N when weather doesn’t co-operate with their anhydrous application.”

He said most producers with Kuhn spreaders treat rain as a friend of their nutrient program rather than an enemy. If wet weather is in the forecast, they load up the spreader with Agrotain or ESN coated granules, knowing the coating will prevent them from losing nitrogen. The slow release lets the crop make optimal use of the nitrogen and moisture.

“And there are a lot of farmers who simply don’t like working with anhydrous for safety reasons or playing with liquid because it’s messy. These guys are going back to granular,” he said.

“Efficiency in the field plays into the equation. Previously, a granular spreader might cover 80 or 90 feet in a pass. Urea covered only 50 or 60 feet. Our hydraulic drive technology lets you spread urea in a uniform pattern 120 feet wide at 15 m.p.h. using your existing tractor.”

The machine can spread up to 1,100 pounds of granular per minute at 15 m.p.h. As well, metering accuracy ranges from 2.7 to 446 lb. per acre.

Pearcy said granular fertilizer is probably the lowest risk method for fertilizer application but admitted that the words “spinner” and “precision” is a difficult concept to convey.

“No, a typical spinner broadcast spreader from any manufacturer cannot be called a precision applicator, but the AXIS 50.1 H-EMC-W is not just any spinner,” he said.

“It is a precision ag machine because the discs function differently than in any other spreader. We take a reading on the discs once a second. If you set it for 200 lb. per acre, you get exactly 200 lb. per acre whether you slow down or speed up, go up and down hills or run on side slopes.

“If a guy is already using something like a JD2630 or Trimble FmX1000, or some other more advanced precision farming system, he can use his section control function on our spreader.”

Pearcy said a farmer with a new Kuhn spreader should have little trouble setting up the machine and getting it smack on target the first time, regardless of his fertilizer source.

Kuhn has conducted 40,000 calibration and uniformity tests on virtually every granular fertilizer on the market, so it knows how each distinct product will react in the disc and what adjustments are needed for the best performance.

The information is presented in chart form, which allows farmers to match their spreader to their fertilizer and make the adjustments. Kuhn also supplies test kits with catch-pans so farmers can do their own in-field checks across the entire width of the spread.

“To make sure we have good even coverage on the overlaps, our spread pattern is shaped somewhat like a triangle,” he said.

“We have 80 percent of the product fall in the main target area while the other 20 percent falls out toward the far tips of the triangle. Then when we come back, that tip of the triangle gets filled in with the remaining 80 percent. The result is close to perfect uniformity in any situation because there’s no sharp edge at the extremity of the spread. It’s a gradual overlap.”

Pearcy said a farmer who dials in 100 lb. per acre will achieve a rate of 99 to 100 lb. across the entire application width.

He said the electronic mass control system makes the high degree of accuracy possible. The two discs are hydraulically driven, and as the hydraulic drive goes under load, it creates backpressure in the lines, which can be measured by a sensor on each disc.

The sensor instantly measures the resistance when a fertilizer prill lands on the disc and knows it’s weight. The machine knows all the values and characteristic of that prill because the fertilizer product has already been entered into its memory bank.

If the hydraulic sensor for the left disc tells the computer it’s moving five lb. per minute of this particular fertilizer, the computer immediately knows the operation is putting down 60 lb. per acre of product.

“The system takes that reading once every second. It’s continually compensating for ground speed, slope, density and the prescription map,” he said.

“The moment you move from one management zone to the next, the controller follows the instructions on the prescription map and makes the necessary adjustment.”

Kuhn engineers determined that disc speed and the prill drop point in the spinner chamber determines how far the granules will be thrown. As a result, the operator can adjust the drop point to determine the spread.

It is a manual adjustment on the smaller 30.1 and 40.1 machines and an in-cab adjustment on the 50.1 H-EMC models.

The optional Kuhn Quantron A/E-2 virtual terminal allows the metering outlets to be automatically adjusted to maintain the correct rate. The ISOBUS terminal is compatible with all other ISOBUS devices found in tractors and home computers, as well as N-Sensor systems. It features a work controller that handles up to 200 fields.

The system can also be programmed to provide a uniform spread without overlap in the headlands. Two weigh cells are built into the mounts where the spreader attaches to the tractor. Weight data from two sources allows the controller to make adjustments for side slopes.

The drop point and disc speed can be manipulated to such a high degree that the spreader is capable of section control with four distinct sections on each side of the machine. Because the spreader is hydraulically powered and regulated, it is independent of the tractor revolutions per minute.

The agitator feeds the fertilizer to the correct drop point in the spinner chamber. It’s electrically driven so it can stop immediately every time there are enough granules positioned over the drop point. This prevents extra grinding and handling of the granules.

It rotates gently at 17 r.p.m. to prevent granule damage and powdering. The granules are guided to the chamber with a brush to ensure there are no empty spots or large clumps going into the spinner paddles.

The 141 cubic foot hopper is esquipped with ladders for safe access. It has clear viewing windows for manual checking of the level.

All components of the spreading mechanism are stainless steel and the paddles are coated with tungsten carbide for longer life.

For more information, contact Pearcy at or visit

About the author



Stories from our other publications