Spreading 2 types of fertilizer at once: these are the options
Spreading 2 types of fertilizer simultaneously is possible, either as a mixture or by using 2 spreaders at the same time. Here is an overview of the pros and cons.
Nitrogen, phosphate, and potassium are 3 key nutrients and make up the majority of applied fertilizers. From a labour perspective, it is efficient to spread them all at once with a single spreader. For decades, this has been achieved using compound fertilizers where different nutrients are combined into a single granule or through blends of various fertilizer types.
A well-known example is potassium chloride (kali 60), which has an angular shape and separates quickly when mixed with other granules. The industry has addressed this issue by producing fertilizers in granule forms and sizes that match those of CAN (calcium ammonium nitrate), solving the separation problem. However, the additional processing required to create such blends increases costs. Straight fertilizers are therefore cheaper than blends, as every extra step adds time and expense.
Another limitation of blends is that the ratio of components is fixed, whereas precision farming might require varying quantities of each fertilizer. Spreading each fertilizer separately is an option but demands extra time and passes. Fortunately, there’s a solution for this as well.
Using 2 fertilizer spreaders simultaneously
Back in 2017, Amazone introduced the possibility of using 2 fertilizer spreaders simultaneously — 1 mounted on the front hitch and 1 on the rear hitch. The manufacturer developed software to manage spreading functions in a mirrored setup, including boundary, edge, and ditch spreading. The optimal switch points for section control (SwitchPoint) are also adjusted for the mirrored configuration. Kverneland offers a dual-spreading system as well.
The main difference compared to using a single spreader is the need for dual Isobus control. The terminal works with 2 GPS lines at headlands because the front and rear spreaders are switched on and off at different times. With manual control, this has always been challenging for single spreaders, and it becomes even harder with 2.
Additionally, for the front spreader, left and right are reversed, requiring adjustments in the control system
Defining 2 implements in GPS
At present, Amazone and Kverneland are the only 2 manufacturers offering a plug-and-play solution for combining a front and rear-mounted spreader. In principle, any fertilizer spreader can be used on the front hitch. The spreading pattern remains consistent whether driving forward or backward. In the GPS system, 2 implements need to be defined, as is done for row applicators on seed drills. It is also important to set up separate headland boundaries for each spreader.
One practical challenge is that mechanically driven spreaders are often designed for a 540-rpm PTO. However, front hitches typically run at 1,000 rpm. Furthermore, the rotation direction of the front PTO is often reversed. These issues can be solved by installing an intermediate gearbox or a hydraulic drive. Another consideration is boundary spreading or task map-based spreading. With a front spreader, left and right are reversed because the spreader is mounted backward, requiring adjustments in the control system. While these challenges can be addressed, Amazone and Kverneland offer complete factory solutions to handle them.
Front and rear combinations more common abroad
Discussions with suppliers, including those who do not offer specific packages for front and rear combinations, reveal that while there is market interest, few investments are made. The advantages are clear, including improved weight distribution, but the required investment is more than double. 2 spreaders and the necessary modifications significantly increase costs.
A practical issue is that a large front-mounted spreader severely limits the driver’s visibility. A company seriously considering this investment opted instead for mounting two spreaders on a single chassis. This solution allows a relatively light tractor to manage the load. Although the tractor must pass over the field twice, this approach saves time when working far from the farmyard.
In countries like France, using front and rear-mounted spreaders simultaneously is more common. If working with a single fertilizer type, the system increases hopper capacity. It serves as an alternative to a larger spreader. Improved weight distribution is an added benefit.
