Where does the fertiliser come from?
The first part of the “Solid & liquid fertilisers” series dealt with the question of when maize needs nutrients. This part takes a look at the technical aspects of nutrient supply, answers the question of how and where fertiliser can be applied with the Maestros and gives an outlook on future objectives.
Underground fertilisation
At the end of the 20th century, the fertiliser device increasingly became standard for single grain seed drills. Today, it is impossible to imagine maize seeding without the conventional underground fertiliser coulter - almost every machine in this sector is equipped with it.
For the Maestros, two different types of coulters are used: a single disc fertiliser coulter and a double disc fertiliser coulter. The single disc coulter is the most common version. Regardless of the machine type, it always has its own suspension which is parallel-guided or rubber-cord mounted. As a result, there is no interaction between the seed row and the lower working fertiliser coulter. Stones or vibrations, for example, can cause disturbances at the fertiliser coulter, but they do not have a negative effect on the seeding result.
The horsepower requirement of the single disc fertiliser coulter is very low, and it penetrates the soil reliably even in heavy and hard soil conditions. The coulter pressure can be adjusted hydraulically or mechanically according to the conditions of the site. Due to its stable design and the carbide-coated skid, it is ideal for high operational speeds. Moreover, the lateral depth control roll reduces earth movements to the side and prevents soil from breaking apart in wet conditions. The working depth can be adjusted flexibly between 5 and 9 cm. When working without fertiliser, the fertiliser coulter can also be lifted and deactivated without tools.
As an alternative to the single disc coulter, a conventional double disc fertiliser coulter can also be mounted on the Maestros for underground fertilisation. It is attached directly to the seed body and, thus, its depth can be controlled precisely. This coulter is partly still used on very, very light soils.
Solid fertiliser
For conventional solid fertiliser application, the fertiliser is supplied either via the Partner FT front tank or an integrated central fertiliser hopper for all machines in the Maestro series. The central hoppers are mainly pressurised hoppers. The advantages are a reliable metering process and the avoidance of fertiliser dust while metering. All in all, the pressurised hopper system provides more flexibility and greater reliability when metering even with high fertiliser application rates. For some machines, double fertiliser hoppers are available as an option, for example to carry different single component fertilisers along which can then, depending on the requirements, be mixed individually via a manual control system or application maps while metering.
The time windows for seeding are tight. To work as efficiently as possible during this time, HORSCH offers different systems with regard to the hopper partition. Thus, the ratio of fertiliser and seed can be ideally adapted to the crop and the fertiliser strategy. This means that a higher quantity of seed with a lower fertiliser application can increase the range to cover more land in a shorter time as the hopper partition and the seed quantity reduce the filling stops.
An optional agitator shaft is available for the fertiliser tank for poorer fertiliser qualities or for fertilisers that have been stored for too long. It is not driven permanently to avoid an additional constant oil consumer. The agitator shaft only works occasionally to prevent a bridging effect but at the same time to not damage or grind the fertiliser. The agitator shaft therefore ensures that the fertiliser is applied safely, regardless of the quality.
As an alternative to underground fertilisation, almost all models can be equipped with a contact fertiliser system as an option. A small amount of solid fertiliser is applied directly into the seed furrow at the grains via an adapted fertiliser system. In this case, there is no need for fertiliser coulters on the machine. This system is ideal if, for example, nutrients have already been applied on the field in advance by mineral or organic fertilisation or will be applied later (e.g. in liquid form). Contact fertilisation is ideal to optimally supply plants at an early stage and promote rapid juvenile development. If, for example, climatic conditions require early seeding in still wet, sticky soil, contact fertilisation can be a great advantage. It prevents that too much soil is disturbed by a fertiliser coulter and that a wedge is cut out between the fertiliser and the seed furrow. Nevertheless, a targeted starter nutrient supply for the plants can take place.
As already mentioned in the first article (When does maize need nutrients?) contact fertilisation is about the starter nutrient input and the supply of nutrients to the plants from the time of emergence until the time when the fertiliser that was applied in advance has been developed, the soil has warmed up and mineralisation has begun.
Microgranular unit
Each HORSCH Maestro can always be equipped with at least one microgranular unit for the application of fertiliser granules, plant protection agents (depending on the region), slug pellets (observe individual approval situation) and undersown crops. The standard solution is the central hopper with pneumatic distribution via a separate microgranular distribution tower and the application in or on the row. The specifically adapted metering technology ensures that the usually very abrasive granules are applied safely and without material wear. Double granule solutions are already available for some of the machines (e.g. MiniDrill and/or front tank) which allow for various combinations. Nutrients and crop care agents are applied in the row while slug pellets, for example, are spread on the row via the rear application spot by means of a baffle which is particularly effective in preventing slug damage in rapeseed, for example, and can save an additional pass.
With the introduction of the new electronic system (I-Manager) for the Maestros, it is possible to set up a microgranular system on each individual row that is independent of the rest of the machine - i.e. independent of the fertiliser hopper and the rest of the machine equipment. The background is as follows: large machines of the Maestro series are primarily equipped with a central hopper for easier filling, higher capacities and therefore a wider range. In the smaller segments where the machines are equipped with normal 70-litre seed hoppers, all models can be equipped with a microgranular unit on the row in the future to apply smaller quantities of microgranular compound mechanically. This microgranular unit on the row is located behind the seed row tank and can be switched off individually by SectionControl to save granules resp. to meter each row individually.
Microgranulate unit directly at the row. 
Central microgranular tank with a capacity of 300 litres.
Liquid fertiliser
The Maestro SV L/SX L series is equipped with liquid fertiliser equipment as standard. There is a central hopper for seed and a tank for liquid fertiliser which contains a pump control as well as an individual row monitoring of the liquid fertiliser application. The sectional switching is carried out via a system that will also be fully integrated into the HORSCH electronics in the future. The sectional valve control allows for switching off the liquid fertiliser application. In the 3-point segment, liquid fertiliser equipment is available as an option, e.g. via the Leeb CT (liquid front tank).
Maestro 24 SX L with liquid fertiliser equipment. 
Liquid fertiliser monitoring system
There are three different application points to react to moisture and soil conditions. As a starter nutrient, the fertiliser can be applied directly in front of the drop/shoot tube. As an option, the liquid fertiliser can also be applied behind the catching roller in the seed furrow. This may be necessary in wet or sticky conditions to ensure a good embedding of the grain by the catching roller and to prevent unnecessary smearing of the side walls of the seed furrow.
A special liquid fertiliser single disc coulter was developed for the underground application of liquid fertiliser, based on the normal solid fertiliser single disc coulter. By reducing the angle, it has been adapted to the application of liquid fertiliser to cause less soil movement. Moreover, it contains a corresponding hose system for liquid fertiliser.
In the future, HORSCH aims to offer a liquid fertiliser option that is individually adapted to the different Maestro models for every machine: integrated, with a saddle tank or in combination with the Leeb CT front tank a pre-series version of which will be tested with various combinations in 2025. The hose system for liquid fertiliser application is already available for some machines, but functions such as flow monitoring and sectional shut-off are not yet fully integrated and are only available in combination with the I-Manager. Currently, the R & D department is working on making the liquid fertiliser option standard in addition to solid fertiliser, which already is available as standard for all machines. A big step in this direction is to create variance and combinations.
In the next terraHORSCH, we will report on the agronomic findings of our test series with regard to fertiliser application and the combination of different fertiliser methods.