Ultra-accurate systems raise bar for fertiliser spreaders
Go for the full complement of electronic technologies available and a fertiliser spreader will be one of the most technologically advanced machines on the farm, providing the highest level of accuracy and ease of operation.
The “humble” fertiliser spreader has come a long way since the days of single discs and waggling spouts. Today, thanks to intensive studies of material spreading characteristics and electronics software development, the fertiliser spreader can be one of the most sophisticated items of equipment on the farm.
Enter a few fertiliser product details on the touchscreen controller, shift the tractor or spreading truck into gear and move off.
With a growing number of applicators, that is all that’s necessary to get fertiliser spreading under way with the highest levels of accuracy. What about calibration? The machine will take care of that.
How about making adjustments for variability in the bulk or changing ambient conditions? It will take care of that too. Boundary spreading? No problem. And what about the challenge of cutting off at the right time and starting spreading again on headlands and for short work?
The most sophisticated models will handle that more effectively than the most experienced operator! It all adds up to easier operation, detailed documentation, improved distribution accuracy and making the most of fertiliser as a critical crop input.
Starting point of fertiliser spreaders
The fertiliser spreader tech fest began with control boxes incorporating calculators that simplified the process of determining appropriate settings for different materials and working widths.
It progressed with in-cab adjustments using hydraulic cylinders and electric actuators, and then to auto calibration – not just at start-up but throughout the spreading programme – thanks to the installation of weigh cells.
These enable the control electronics to calculate the flow rate of material on gravity-feed spreaders, check whether that delivers the required application rate and, if not, automatically make fine adjustments accordingly.
With the field treated, the amount of fertiliser allocated to the job should be the amount applied – no shortages and no leftovers.
And, with GNSS tracking data collected in the process, a record of precisely where and how much fertiliser has been applied is created that should satisfy any farm assurance and environmental stewardship requirements.
More recently, on board job computers to work with dedicated controllers or Isobus universal terminals – and also tablet computers as well – have brought control familiarity and additional functions.
Variable rate fertiliser spreaders
In contrast to blanket treatments, variable-rate application from maps and crop sensors makes optimum use of fertilisers, especially across fields with significant soil nutrient variability, by ensuring appropriate nutrient dose levels where they are needed.
Significant savings in the total quantity of material applied can also result from this technology, but optimum usage is arguably the more important benefit when reflected in crop yield and economic performance – and environmental impact.
Much the same goes for automated on-off and spreading width control for headland approaches and departures, and where treated areas converge in irregularly shaped fields.
These are the most recent challenges mastered by mechatronics engineers at the fertiliser spreader manufacturers – systems that mimic the “section control” functions developed for crop sprayers.
With air boom fertiliser spreaders, section control is relatively easy to adopt – it’s a bit of a simplification but all it takes is a shut-off mechanism for the metering roller for each outlet and incorporating appropriate position offsetting into the control software.
Spinning disc broadcasters
It’s rather more complex on spinning disc broadcasters, given their fan-shaped output and the way the dosage is built up in multiple layers. But the engineers have cracked that one, too, investing in performance testing resources and software development to create different solutions.
These modify where the fertiliser lands on the ground without upsetting distribution evenness across the narrower spread, while trimming delivery to the discs to maintain the correct application rate.
This is achieved by altering disc speed on hydraulic-drive spreaders or the feed-on point of pto-drive machines – or a combination of the two – in response to signals from the section control feature of a control terminal with GNSS input.
Basic systems bring the spread pattern in from one side or the other, while more advanced versions can manipulate the spreading width on both sides simultaneously to minimise over-treatment.
And the level of definition has increased enormously – from just four sections across the whole width to as many as 128 sections or steplessly variable.
The potential savings achieved by this sophisticated electronics and spreading adjustments technology are clearly dependent upon the size of fields and their shape.
But 5-15% in “typical” European arable fields is a common claim borne out by a comparative study commissioned by manufacturer Sulky Burel.
Researchers at the French national institute of science and technology for environment and agriculture (IRSTEA) compared manual control of a Sulky tractor-mounted fertiliser broadcaster with automatic operation using the manufacturer’s Econov spreading width regulating system.
Under both protocols, ammonium nitrate fertiliser was applied from the spreader set up for a 24m (78ft) working width. In manual control, the operator opened and closed the hopper shutters at headlands based on his own judgement.
With auto control, the Econov system used GNSS position data, forward speed and so on to determine shutter opening and closing points, and to close down and open up the working width as appropriate.
Sampling determined that while manual control achieved 45% evenness of application within +/-15% of the target dose rate, that figure increased to 68% with the Econov system, and with under- and over-dosing virtually eliminated.
Moreover, there was a 9% reduction in the total quantity applied – 1.38t versus 1.52t.
Sulky Burel not only welcomes confirmation of the potential for input cost savings, but also highlights the beneficial effects on the crop of optimising fertiliser dosage, and on the operator of automating the more challenging aspects of broadcaster operation.
So, do the highest-spec machines detailed in the following product listing represent the peak of fertiliser spreading accuracy?
Probably, because it is difficult to imagine what else can be monitored and controlled: as ever, commercial uptake will be determined by the cost of fertiliser and, therefore, the value to be gained from any material savings, as well as by farmers’ hunger for precision.
Novel technology at a glance: Radar and a twin-belt system
Amazone: Argus Twin
Constant monitoring of fertiliser distribution using radar technology is an option on Amazone ZA-TS spreaders equipped with Isobus electronics.
Argus Twin, comprising an array of radar sensors above the spreading discs, checks whether the trajectory of fertiliser granules is correct for the required spread width.
This can be affected by inconsistencies in the fertiliser, worn discs and vanes, and by working on slopes.
Deviations are automatically corrected by individually altering the feed-on point to the two discs, and the system remains active when border spreading or when the pattern is narrowed under GPS switch control.
Rauch/Kuhn: Electronic Mass Control
The Electronic Mass Control (EMC) system developed by Rauch for its range of spreaders marketed worldwide by Kuhn monitors the application rate delivered by each of the two broadcasting discs.
It does so by measuring minute changes in torque at the drive shaft for each disc, which is proportional to the volume of material being propelled by the distribution vanes.
While weigh cell installations enable control systems to calculate whether the spreader is delivering the required rate, Rauch points out that although the rate may be correct overall, such methods do not detect differences between the discs.
Bredal: Twin Belt
Like others in the Bredal spreader range, the F Series mounted and trailed models deliver fertiliser by volume from hydraulically driven rubber belts.
But instead of a single belt for both discs, these machines have individual feed belts, so that the feed rate can be adjusted when the section control facility adjusts the spreading width on one side to reduce over-application in wedge-shaped areas of the field.
Spreading width can be brought in on one side only or both sides simultaneously in up to 12 steps. This is achieved by using an electric actuator to change the position of stainless steel chutes and so alter the fertiliser feed-on point, which reduces the velocity of material thrown from the disc vanes.
Highway Equipment Company: Swath width control
Swath width control to eliminate excessive double application of fertilisers and other dry nutrients is a new feature of the truck-mounted spreader produced by the New Leader division of US manufacturer Highway Equipment Company.
Adjustments in spreading orientation are made by altering the feed-on point for material dropping on to the spinning discs.
But, unusually, this is not achieved by adjusting the feed chute or baffles as on some spreaders but by shifting the entire disc assembly to left or right, forward and back.
The G5 swath control technology was developed in partnership with precision farming specialist Ag Leader and provides 16-section swath width control to minimise double application where swaths converge and half-width spreading to headlands if required.