Back to the future - How innovations from the past meet the requirements of today
At the Agritechnica 2023, HORSCH presented the Leeb Xeric, reviving a development project from 30 years ago. In this interview, Theo Leeb explains how it came about, what characterises the pneumatic fertiliser spreader and what experience has been gained.
terraHORSCH: Why is the Xeric more of a re-entry than an entry into fertiliser technology for HORSCH LEEB?
Theo Leeb: The Xeric is not the first pneumatic fertiliser spreader we developed. There already was such a device in 1994 made by Leeb. It was the first development project I did for Michael Horsch. In the 90s, two prototypes with a working width of 24 m were built. The objective was to spread fertiliser with high precision. This means with an application map based on soil samples. At that time, we were already able to implement VariableRate and VariableRate per Section as well as SectionControl. The main field of application was basic fertilisation, especially potash.
However, the market was limited at that time. In addition, the focus of farmers on GPS technology and precision farming was far from being as intensive as it is today. You could say that the market wasn't quite ready back then which is why this development was not followed up.
What tipped the scales for you to revive the pneumatic fertiliser spreader project?
The first machines were developed 30 years ago - a lot has changed in fertiliser technology since then. The demand for precision in particular has risen significantly and is increasingly approaching the level of plant protection. At the same time, the focus more and more is on aspects such as efficiency and the increasing shortage of labour. Centrifugal spreaders often reach their limits with regard to working width. 36 m often is the maximum. In some regions, this already is a considerable compromise.
Today, precision is required for two reasons: on the one hand, legal provisions such as the distance to water bodies. On the other hand, to utilise operating resources efficiently. Moreover, there are shorter time windows for application because of the climate. External influences such as crosswinds can cause significant irregularities in lateral distribution.
In addition, in the past years, customers repeatedly asked us if we would be interested to get back into this sector again. So there apparently was a demand. This made us take up the project again in 2022.
What did you learn from the prototypes of the 90s - and how have these experiences been included into today's concept?
Basically, we learnt two things. Firstly: if we want to achieve high application rates at high operational speeds, it only works with a pressurised hopper solution where the entire metering system has the same pressure level - similar to the large seed drills. This means that the pressure for the main hopper is the same as for the metering units. Thus, there is no need for an injector which would result in a major performance loss.
There are two options for transporting fertiliser or seed by air flow. In the first option, an injector is used to generate a vacuum, the material to be transported is sucked in and transported further in the air flow. This principle requires a lot of power to generate high quantities of air. The second method is the pressurised hopper method as it is used for large seed drills - with excellent results. In this case, the air pressure in the entire system is the same. This allows the material that has to be transported to fall freely into the transport air flow. We were already working with a pressurised tank in 1994.
The second thing we learnt from the past is that pneumatically transported fertiliser is as abrasive as a sandblasting system. Routing around corners and hoses are therefore subject to heavy wear – if possible, bends had to be avoided. We made this mistake in 1994 and learnt from it the hard way. At that time, the metering units were located under the tank, as, in our opinion, this was the easiest solution as the fertiliser could fall directly from the tank into the metering unit.
However, this makes the air flow and therefore the transport distance rather long. The fertiliser has to be transported under the entire chassis to the rear and into the boom, passing through many hose lines and bends along the way. At that time, this led to chafed lines in a relatively short time. We got this under control, but we also knew that it could be done better. The concept for the Xeric was then developed from these considerations.
What is this concept based on?
We wanted to keep the transport path for the fertiliser as short as possible. The key to this is the metering tank in the middle section of the boom. This means that the fertiliser has to be transported through the boom to the nozzle in only one direction. The metering tank is placed on loading cells and contains the complete metering system. It is continuously filled from the large hopper via auger conveyors. This layout allows for realising high application rates with a relatively low air output.
What are the excelling features of the Xeric?
In a nutshell: precision and efficiency. Currently, we can realise working widths of up to 48 m and, in combination with plant protection technology, we see 48 m as the new future working width for larger farms.
The Xeric comes with twelve boom sections - depending on the boom width, 3 or 4 m sections can be realised. With the same precision as the crop care sprayer, with SectionControl, CurveControl and VariableRate per section. It is mounted on a chassis similar to that of the Leeb 12 TD with active steering - for high manoeuvrability - and tyres with a diameter of up to 2.15 m.
A major advantage is that you can work largely independently of the wind and at a high speed. In addition, fertiliser quality plays a subordinate role. I would even say that it plays no role at all which provides economic advantages.
The Xeric has a PTO shaft-driven hydraulic supply which means that the hydraulic power of standard tractors is sufficient. As far as the tractive power requirement is concerned, we are talking about the 300 hp class for the Xeric.
The fertiliser spreader was presented at the Agritechnica 2023. What are the practical experiences?
Our objective right from the start was to automate the calibration of the fertiliser. Weighing elements on the metering tank will take over calibration resp. recalibration This component is currently optimised. This season's experience shows that this is necessary, especially for customers who switch between fertiliser types quite frequently during the day. The refined version of manual calibration will also be ready for next season.
Initially, there was a great deal of scepticism regarding the transport of fertiliser to the metering box via augers. We were worried that the augers would grind up the fertiliser too much. In our opinion, this concern proved to be unjustified. The fertiliser can be applied in the same way as it is filled in. If granulated fertiliser is poured in, granules come out; if dust is poured in, dust comes out.
The fertiliser spreader has a tank capacity of 14 m3. What does this mean for farm logistics?
With regard to fertilising, logistics is the key to overall performance. The large tank capacity means that in times of labour shortages, one person can cover almost the same area as a spreader driver and a feeder driver used to.
The crop care sprayers are characterised by the boom control system BoomControl. What role does it play in fertiliser technology?
In crop care technology, the boom control system is a decisive key to reduce drift by means of a low boom. In fertiliser technology, the issue of drift only plays a very minor role. However, precise boom control is crucial for lateral distribution and higher operational speeds. We therefore offer the same precision for fertiliser, too.
Are there any limitations compared to conventional technology?
The boom means that the Xeric is not as agile in regions with small fields. For example, the driver has to drive round poles or the like or fold the boom. This is why we currently see this technology more in larger farms.
Another point, of course, are the comparatively higher purchase costs which result from the fact that the Xeric is equipped with significantly more technology than a disc spreader. Nevertheless, the advantages of the system outweigh the disadvantages in many conditions.
What are the next steps?
The Xeric is currently available in working widths of 36 and 48 m. In the future, we would like to widen our range of boom widths, e.g. offering 39 m in the next step. We are also thinking about a model on one axle - there are arguments for and against. We will see.