Economic analysis of the NawaRo-Maus by the agricultural systems technology department at the Munich Technical University at the Weihenstephan science centre

The ROPA NawaRo-Maus. What may be accomplished with a chaff chain on this loading machine and does this pricy purchase worth it at all?

The structural change and growth of agricultural enterprises cause constant increase of silo facilities. The increasing use of renewable raw materials accelerates it further. Large facilities and corresponding silo facilities were intensely built in the recent years. High demand for biomass and low availability of land require the biomass to be transported from more distant fields and meadows to the facilities. The efficiency of logistics sets before contractors as well as farmers and facility operators growing challenges.

Traditional harvesting methods of chaff have certain weak points. Harvest chains with many transport trailer combinations, necessary for long runs, often cause problems because of numerous vehicles. First problem arise from the necessity to provide large number of drivers, second, the costs of such chains increase enormously at long distances. The reason for it is the declining transport performance of each vehicle alongside with increasing distance. Another issue is of course the inconvenience of local residents who feel disturbed by harvesting chains.


For these reasons, in 2009 developers of ROPA cooperated with several contractors to apply well-recommended methods of sugar beet loading to the harvesting of chaff. Together the loading methods used in sugar beet harvesting were applied to the harvesting of chaff. The result was the ROPA NawaRo-Maus. Used sugar beet harvesters were fitted with two transverse intake augers. A blower was installed centrally between the augers in the pickup to move the chaff to the infeed conveyor. The conveyor and conveyor arm were enclosed to prevent the chaff from blowing out. The conversion gave the machine an easy second career as a chaff harvester after the hard work of harvesting sugar beets. Chaff is much lighter to load than sugar beets and operation in poor weather conditions is not usual.

In order to analyse the efficiency of this new and initially slightly strange logistics system, the Agricultural System Technology Department of the Technical University of Munich under the direction of Prof. Dr. Bernhardt in cooperation with ROPA Fahrzeug- und Maschinenbau GmbH published a bachelor thesis. In the course of this work some of the harvest chains were accompanied throughout the day and some vehicles were equipped with GPS receivers. The collected data were evaluated with analysis program at the Department. Thus, it could be determined how long the chaff cutter really worked during the day or stood without work on the field because, e.g. there was no free vehicle at place. In addition to GPS analysis, extensive interviews were conducted with operators and customers of chaff chains performed by ROPA NawaRo-Maus and the chains were calculated taking into account different harvesting capacity.

The NawaRo-Maus system is more economical at transport distances below 8 km.

The loaders are based actually on used euro-Maus3 vehicles and have 6-cylinder Mercedes-Benz engines of 220 kW/299 hp and 7.2l working capacity. They offer a torque of 1200 Nm at 1300 to 1600 rpm. The powerful engine enables the harvester to load 12 to 15 m³ a minute with its 8.0 m wide pickup. It fills a truck completely on 4 or 5 minutes. Power is transferred from the engine to all moving parts and the traction drive exclusively hydrostatically. One of the great advantages compared to other truck loading systems is the movable truck conveyor arm. It can load the chaff up to 13 metres away (from the centre of the pile) and up to 6 metres high. This capacity bridges field edges, hedges or ditches without difficulty.

The longer the pile at the field edge, the greater losses are caused by the residual sublayer. This layer is left to prevent the crop from dirt and stones insertions. However, a pile should not be infinitely long. Practice has shown that large chains easily get along with piles of 75m long and 7.5 m wide. For smaller fields shorter piles are sufficient.

If the loader has already worked over a good part of the pile, the field cart can load behind the loader on the same area. Thereby, the chaff loss can be minimized on the field surface. About 3.7 t of chaff can be lost per pile of 75 m long. It sounds enormous for smaller fields. However, the chaff can be brought from the several fields to the central overloading place. This minimises losses. However, if the losses are subjected to a business analysis, it can be quickly concluded that cleanliness and thoroughness do not always pay.

The increase in output of the complete chain from an average of 90 t with conventional harvesting chains to an average of 120 t makes this very clear. The anticipated contamination of the chaff by the soil layer is not observed in practice. On one hand, the position of the pile is checked briefly for stones before tipping the first load. On the other hand, the pickup is not lowered to just above the ground until the last pass over the pile. This reduces the danger of including stones or earth with the chaff to a minimum with the simplest methods.

A major difference between the systems is also evident in the average waiting time of the chaff cutter. The chaff cutter in the traditional system waits an average of 21.3% of his fieldwork time. It includes only time when the chaff cutter really stood on the field and there was no tractor-trailer around. The waiting period in overloading system with NawaRo-Maus comprises only 4.9% of the fieldwork.

This significant difference is expressed also by two means. On the one hand, the truck loading chain at 120 t can load significantly more per hour compared to the traditional chain of 90 t, although both chains use chaff cutters with the same power range. On the other hand, the work in field and in silo facilities becomes more quiet. This fact has already been praised by many contractors and their customers.

One of the main issues for every professional farmer and contractor is of course cost. The largest differences in the chains consist in the acquisition costs of the vehicles and interaction of the vehicles in the chain. A professional tractor-trailer with a 50 m³ chaff cart and a driver costs 92.69 euros per working hour. A semitrailer costs 69.43 euros, but comes with a 65 m³ trailer. The truck trailer is cheaper, has higher load capacity and at the same time more power. A tractor has a power output of 250 hp, and a truck - 430 hp.

Considering the total transport costs of harvesting chain from the field to the silo facilities, the following things become apparent. The traditional chain with relatively short field-silo facilities distances is more favourable in transport/chaff ton price. The overloading system initially costs more than the traditional one. The reason is simple, in order to get the chain running, you need a chaff cutter, NawaRo-Maus and two tractor-trails on the field. Add also trucks on the road. However, the traditional system costs grow rapidly with increased distance, comparing to overloading system. it happens mostly due to the lower transport capacity of the tractor-trailer. It can drive max. 50 km/h and also has lower load volume. Using chaff carts you are limited with 50 or 55 m³ of load volume, trucks with dump trailers provide 60 m³ of load volume and even up to 90 m³ with sliding floor trailer!

The mentioned difference in speed between the tractor and the truck was also investigated. It showed that the trucks achieve a transport speed of 49.0 km/h in the chaff chain. On the contrary, the tractor-trailers managed an average of only 29.7 km/h.

In addition, the tractor-trailer is more expensive. The unit with a 250 hp tractor and 50 m³ chaff cart costs about 243,000 euros. A truck-trailer with 430 hp and 65 m³ trailer has a purchase price of only around 165,000 €. This fact is also reflected in the costs difference. Higher initial costs result in higher depreciation, which is also important to mind counting the operating costs per working hour!

Another advantage of the truck-trailers is that they can offer a completely different advantages compared to tractor-trailers. They can be used during the whole year for efficient and cost-effective transportation of agricultural goods. In addition, it is much faster and easier to rent the highway giants during the current harvest season. It is possible for a producer without drivers or a shipper with its own drivers. The Nawaro-Bunkermaus loads the chaff directly into a bunker. This eliminates impurities.

Everything, that can not be valued in euros and cents in the calculations, is the external benefits. Using of trucks doesn't arise complaints about noise pollution. According to contractors' statements, residents of areas with larger biogas plants only noticed that the harvesting had begun after a few days. The trucks are much more quiet and anonymous than tractors, because of their tires, especially in inhabited areas. It is difficult to see what load a passing truck is carrying and what its destination is. The situation is similar with the road contamination. The large-volume trailer does not need to be filled right to the top to transport a greater load than a chaff trailer.

The covering devices of the trucks reliably prevent the chaff from blowing off and trickling and avoid from contamination of roads and localities. Not to mention that in wet weather conditions tractors make the roads dirty by the adhering on tires soil.

In summary, we can not dismiss economic efficiency and impact of the chaff logistics. The organisation of the chain remains the most important thing! A truck driver can not be treated simply as a tractor driver. The driving and break time should be strictly adhered to and it must be ensured that all truck drivers do not make break simultaneously. If these conditions are not considered, at some periods no trucks will come to the loader and then suddenly four trucks will be waiting to load. It increases the waiting time and, thus decreases efficiency. Moreover, it may be natural that the pile is needless prolonged, which further increases the losses. It has been proven in practice, that the load driver should in addition to his load work coordinate the trucks and sent them according to the requirement to break. He can best estimate how much crop has to be loaded and if he gets to the chaff cutter behind.

Some professionals may not dare to rely on this technology, despite the immense potential of this logistic process, still it remains impressive that only by changing the logistic means, the same chaff cutter can harvest in average 33% more corn as with the traditional system!

If you want to avoid the losses of chaff laid on the filed and change to cost-effective and efficient truck transportation, we can advice you a very similar machine from Palandt Agrartechnik GmbH. The so-called Nawaro-Bunkermaus has instead of the feed augers, a receiving hopper with about 15 m³ volume. The tractor-trailers on the field gather crop without soil contact, directly into the bunker, from where it is overloaded by conveyor belts to the waiting trucks. Thus, losing the great advantage of dissociation of the field and road logistics, you win on strong flexibility and operational reliability of the self-drive system with the loader.

Johannes Wutz

Bachelor of Agricultural Sciences

Prof. Bernhardt
Agricultural System Technology Department of the
Technical University of Munich