New Horsedrawn Minimum Till Seed Drill
Report from Schaff mat Päerd
Multi-purpose Seeder SmP Kombi-Séi 1.2 for Horse Traction
by Paul Schmit of Tuntange, Luxembourg & Albano Moscardo of Verona, Italy
By multiple field tests, the possible range of use of the new multi-purpose seeder SmP Kombi-Séi 1.2 for seeding by horse traction was analyzed.
Tests and measurements in spring and summer 2016 showed that this implement requires a moderate draft power of a single hitched draught horse, this with various coulter options on different soils and terrain slopes.
By the possibility to fit either shoe or disc coulters in combination with different covering harrows or press rollers, it comes up with good working results. By the coupling to the SmP Mono-Rad 1.2 single-wheel forecart, which lowers the draft, support and steering efforts, a good working comfort for the horse is guaranteed.
In order to improve the working precision, the retrofitting of a steering device should be envisaged. Furthermore, adaptations on the coulter lifting mechanism could improve the terrain suitability and extend the range of possible coulter pressures.
Further information about a horse’s acceptable draft power can be found at www.schaffmatpaerd.org.
The physico-chemical degradation of the soils world-wide by so-called “conventional” farming methods is considered as one of the major problems for the world’s food supply in the coming decades. Organic farming systems, refraining from the use of genetic engineering and chemically-synthesized sprays and fertilizers, can help resolve this situation. However, a better protection of the soil is also closely linked to agricultural engineering.
By that, minimum tillage or no-till seeding is gaining popularity among tractor farmers around the world. Not just the prevention of soil erosion or the preservation of the rich and valuable biodiversity in the soil are the main arguments in favor of this farming methods, but also reduced fossil energy and time consumption.
However, minimum and especially no-till seeding requires adapted equipment in order to assure enough penetration of the seeding units, equivalent to correct seed placement depth and ground contact. In many no-till seeding conditions, just heavy shank loads, up to 300 kg per shank, assure these performances. In general, conventional seeders, designed to operate on fine seedbeds of plowed and tilled ground, do not offer these characteristics.
For the horse farmers, with a limited living draft power in front of their equipment, no-till seeding in heavy or compacted soil is only possible with very small units, often reduced to one or two shanks with a limited work output. A promising approach, for the time being, can be the development of suitable animal drawn equipment for minimum-tillage seeding, where the soil is cultivated before the seeding operation but not entirely turned over.
As a renewable and environmentally friendly energy source, horse traction is currently undergoing a renaissance in small-scale agricultural holdings, winegrowing, market gardening and forestry. In order to keep up with modern farm machinery technology, one of the goals of the non-profit association Schaff mat Päerd is to develop new equipment and publish related studies.
The test report in hand analyzes the use of a new seeder prototype fitted with various coulters and seed covering devices, capable of working in minimum tillage conditions or mulch. Further information about this implement can be found at www.schaffmatpaerd.org.
Because the topographic, economic and social situations in much of the world do not favor big hitches, this report focuses on a single animal hitch.
Technical characteristics of the implement:
|Model:||Kombi-Séi Concept 1.2|
|Working width:||1200 mm|
|Total width:||1685 mm|
|Total length:||1980 … 2120 mm *|
|Total height:||1150 mm|
|Tare weight:||223 … 239 kg *|
|Support load / SmP Mono-Rad forecart:||8,5 kg|
|Frame:||Tubular steel DN32|
|Seed hopper capacity:||150 l|
|Size of seed outlets:||7 or 13 x ø 30 mm *|
|Seeding rate:||4,8 kg/ha (red clover) … 350 kg (peas)|
|Row distance:||60 / 100 / 200 mm *|
|Transmission:||Single chain drive 1,43:1 / 20-stage gearbox / double gear drive 9,93:1|
|Clutch:||4 finger claw coupling on gearbox input shaft|
|Disc coulters:||ø 320 mm / angle of attack 7° / max. coulter pressure 25 kg|
|Press rollers:||320 mm / max. contact pressure 25 kg|
|Covering harrow:||ø 9 x 350 mm / max. contact pressure 5 kg|
|Shoe coulters:||cross section 43 x 13 mm /max. coulter pressure 5 kg|
|Covering harrow:||ø 6,5 x 270 mm / max. contact pressure 10 kg|
|Wheels:||14 spokes DN15|
|* depending on coulter type|
Horse in the test:
|Breed:||French Ardennes (ID-Nr IR0267)|
|Date of birth:||13.05.96|
|Height:||1,52 m (5 ft) 15 hand|
|Weight:||726 kg (1600 lbs)|
|Collar size:||Coblentz 26″ half sweeny / Svenljunga #02 – 26”|
Materials and Methods
Preliminary tests were executed in July 2015 at the SCHMIT-LAROCHE farm in TUNTANGE (LUXEMBOURG), on September 2015 at the MOSCARDO farm in VERONA (ITALY) and on May 2016 at the EMMETORP farm in HÄLLESTAD (SWEDEN). This was used for seeding cover crops or grass with extra wide shoe coulters followed by a light covering harrow in conventionally prepared seedbeds. For the first two preliminary tests, the hitch consisted of two different types of swiveling shafts and singletree assemblies in combination with leather traces.
The measuring tests took place on the SCHMIT-LAROCHE farm in TUNTANGE (LUXEMBOURG) during spring and summer 2016. For testing the performances in minimum-tillage conditions, the setup was replaced for all trials by the 1.2 version consisting of disc coulters followed by press rollers. Furthermore, in order to evaluate the benefits of the Scandinavian way of hitching draught horses, the third preliminary test as well as all measuring tests were carried out with articulated traction shafts instead of the leather traces and a singletree. Two types of collars, the American and the Swedish style, were used in turn on the horse.
The connection of the steel traction shafts to the harness was assured by scissor flat bars, which were attached to the central tug rings on each side of the harness and secured by a safety quick release pin. As the side straps were also attached to these tug rings, the steel shafts did not only transmit the traction forces, but also the braking and backing forces. The leather front tug straps were adjusted for each tested collar in a 90° angle to the hames and the side straps in a horizontal and direct line to the breeching. This assured a steady contact of the collar pad(s) on the horse’s shoulders and a quick and smooth response of the breeching.
Two draft force sensors, for measuring the left/right side forces in the tugs, were also integrated in the central tug rings. The data logger was saddled on the back pad. By inserting all these components into the harness, it was possible to do the needed adjustments during the harnessing of the horse in the stable and just plug in the speed sensor, mounted on the forecart, as soon as the horse was hitched to the implement.
In order to evaluate the required tractive effort, the draft forces and working speeds were measured during different work as well as on different soil types and terrain slopes. These were:
- Seeding of a biodiversity seed mixture on parcel A – center field with a surface of 0,25 ha and medium heavy flat soil after ploughless minimum tillage (24.04.16)
- Seeding of a biodiversity seed mixture on parcel B with a surface of 0,22 ha and medium heavy soil with a slope of 8,5% after ploughless minimum tillage (05.05.16)
- Seeding of a biodiversity seed mixture on parcel C with a surface of 0,33 ha and light flat soil after ploughless minimum tillage (07.05.16)
- Seeding of forest perennial rye on parcel A – left field with a surface of 0,42 ha and medium heavy flat soil after ploughless minimum tillage (08.08.16)
- Seeding of forest perennial rye on parcel A – right field with a surface of 0,42 ha and medium heavy flat soil after ploughless minimum tillage (11.08.16)
- Seeding of forest perennial rye on parcel D with a surface of 0,36 ha and light soil with a slope of 5% after ploughless minimum tillage (10.09.16)
The parcels B and C were free of stones, whereas on the parcels A and D lighter stones could be found on the surface. All measurements were taken between 09.30 a.m. and 12.00 p.m.
The measuring device consisted of the following components:
- two Lorenz K-100 force sensors mounted between the leather front tug straps and the central tug rings on both sides of the harness
- an AHLBORN FUA9192 speed sensor mounted on the SmP Mono-Rad forecart with optical scanning of an additional disc with reflective marking
- an AHLBORN Almemo 2690-8 data logger with memory connector and micro SD card mounted on the pack pad of the harness
As well as the tractive effort generated by the single hitched horse, the working principle and results for the different works and the operating of the machine were examined. The same horse named Irmi, belonging to the SCHMIT-LAROCHE farm, was hitched for each measurement. The angle of draft was set identically for all measuring on 15° with a shaft carrier height of 350 mm.
From 2011 to 2015 all the parcels A to D were used to grow field forage and were cultivated a week before the seeding by three passes of a tractor driven BOMFORD DynaDrive cultivator. The seeding rate for the biodiversity mixture was set identically for all measuring on 10 kg/ha, corresponding to the 2nd gear in the gearbox and gate latch position 2 of the adjustable outlets. For the forest perennial rye, the seeding rate was set identically for all measuring on 120 kg/ha, corresponding to the 16th gear in the gearbox and gate latch position 3 of the adjustable outlets. For all seeding, the agitator shaft in the seed hopper was engaged.
In order to guarantee the statistical significance of the measurements, the measuring was repeated at least four times, depending on the field size, this with measurement times for the partial measurements between 04 min 27 s and 12 min 00 s. The measured values were recorded with a summary measuring rate of 100 Hz resulting in a frequency of 25 Hz for each of the four dimensions (time, 2 forces and speed). In order to not exceed the scope of the current report, the graphs below represent just a selection of the results, providing an overview of the characteristics of the implement.
On graphs 1.3, showing the 3rd outward and return runs on the center field of parcel A, it comes out that the work with this seeder requires just a moderate draft effort of the horse, this with an average total draft force for both runs of 0,597 kN. This despite the coarse structured soil, resulting from the rainy weather conditions in spring 2016 in large parts of Western Europe.
Contrary to all expectations, this graph shows also a considerable difference between the left and right side forces on the harness, this with a maximum of 35% for the return run. The maximum difference of the left / right side forces for all runs made on this parcel was 40% and the average 35%. For all other following tests B to E, this difference decreased to 0,5 – 10%.
By that, the new harness and hitch setup cannot be considered as the main reason. More likely, the reason for this disparity should be sought within the mental and physical state of the horse. As it was one of the first farm works of the year, besides harrowing grassland, the horse needed more conditioning before making physical efforts again. As the field is located half an hour from the farm, it can be assumed that the muscles of the horse were warmed up sufficiently.
Due to the hard wind, which was blowing during this test, the horse showed some discomfort. This was also reflected in the average working speed of 4,902 km/h, which is faster than the normal step speed of this horse.
The highest imbalance of both forces acting on the horse’s shoulders can be noticed at the headland, where the left force is more pronounced than the right force. This can be explained by the fact that the turn at the headland was executed to the right, resulting in a higher load on the left shoulder. A changing of the turning direction during the work can help prevent an overuse of one shoulder side, especially in hilly working conditions and would also permit to condition both body sides of the horse for a better balance.
This relation between the turning direction and the force distribution on both shoulders is also confirmed by the measurements on parcel B, C and D represented in graphs 2.2, 3.1 and 6.3. Graph 3.1 shows also the variation of the working speed at parcel C, this with no seeder shutting off between the 1st outward and return runs. On all other graphs, the two interruptions of the oscillating draft forces between the turning maneuver at the headland and both seeding runs reflect the rest of the horse during the time needed for lifting the coulters out of the ground and disengaging the transmission for the reverse action.
The half-hour ride between the farm and parcel A is represented in graph 4.0 with the following segmentation:
- A = waiting at the farmyard until village road was free to go
- B = flat run on village road
- C = downhill run on village road with slightly activated brakes
- D = uphill followed by downhill run and waiting at a crossroad at village centre
- E = uphill run at the end of the village road
- F = short downhill followed by longer uphill run on farm track
- G = flat run on farm track
- H = entering the field
The whole run was made on asphalt. The highest tractive effort was required in section E, with a slope of 9,5%, this with an average total draft force of 0,307 kN. For the run on flat asphalt, the seeder / forecart assembly requires just 0,067 kN. All these beneficial test results can directly be assigned to the low weight tubular frame design of the implement in combination with the 36” rear wheels supporting large parts of the implement weight. The pneumatic wheels gave both a very low rolling resistance and a nearly noiseless ride.
The highest draft force peak during the transport of the seeder has been registered during entering the field. As shown in the summary graph 7, the idle run of the seeder / forecart assembly without seeding on arable land, a measurement made on parcel A – left field, requires 0,432 kN. By that, about two thirds of the energy needed during the seeding is spent on the locomotion of the implement itself and one third is spent on the transmission and seeding mechanism.
From the summary graph 7 comes also the measured data of all other parcels. As indicated in the above-noted listing, the parcels B and D feature a slope in working direction of 8,5 respectively 5%. Working uphill increases the draft effort of 40 to 120% compared to the downhill work. The average effort for both runs corresponds to the work on parcel A.
Parcel C, even if being nearly flat, requires 0,718 kN, a notable draft force. This can be assigned to the dry and soft sandy soil, which increases the rolling resistance by a greater sinking in of the wheels.
Despite the small number of 7 disc coulters, used on parcel A – left and right fields, the seeding with this setup requires more draft effort of the horse than the 13 shoe coulters used on parcel A – center field, on average + 17%. This difference can be attributed to the greater penetration of the disc coulters and the functional friction. This not just in the bearings, but also on the discs themselves. Every steel disc coulter is in constant contact with an angled and flexible plastic disc. The combined plastic discs serve for cleaning and depth limiting, this with a tool-less adjustment of the sowing depth. By the greater row distance of the disc coulters, compared to the shoe coulters, a clog-free operation is guaranteed, even with the presence of crop residues on the field surface.
For the work on parcel D, the contact pressure of the disc coulters was increased, by a higher preload of the springs in the coulter suspension. This setting did not affect the draft effort considerably, compared to the seeding on the other parcels, as the plastic discs limit the working depth. However, the higher coulter load assured a more uniform placement of the seed. After a few weeks, with constant dry weather following the seeding, the emergence of the seed on all parcels was controlled and the working results on parcel D could be classified as the best, this with a fine and very even emergence of the seed over the whole field area.
The summary graph 8 shows the average values of the left and right side forces measured on all parcels. From this, it follows that the work with the Swedish style collar, on parcels A – left and right field as well as on parcel D, offers no significant difference compared to the work with the American style collar on parcels A – center field, B and C. By its three-pad design, both shoulder pads of the Swedish collar can follow independently the movement of the shoulders, whereas the solid American collar swings as an entire piece. However, it must be clearly stated that this subject needs further investigation with exactly reproducible measuring conditions. Fieldwork with a lot of influencing factors on the measured data cannot be seen as an accurate analysis.
The machine made very little noise during work, and that resulting mainly from the transmission and the seeding mechanism. The verbal communication between human and animal was not affected negatively. Walking on the left side of the implement affords the carter a good view of the functioning of the machine and at the same time a good nonverbal communication with the horse. In this way, with sufficiently short lines, a sensitive contact with the bitless horse is assured and it is possible for the horse to see the carter (teamster), which refines the communication between the two.
A mechanical lever at the rear, in good reach when standing behind the implement, allows, by a 180° turn, to raise the coulters (in headland) to transport position. By the same movement, the clutch between the chain drive on the right wheel and the gearbox mounted at the front frame, is also disengaged which shuts off the seeding mechanism.
The activation of this lever needs just a small to medium actuating force, this depending on the adjusted contact pressure of the coulters, as the lifting mechanism acts against the springs in the suspension of the coulter arms. Besides the total weight of the implement, this actuating force limits the possible ground pressure of the coulters. For higher coulter loads, a spring assistance of the lifting mechanism would be needed. Turning on and off is preferably done at standstill in order to prevent a premature wear out of the coupling claws. However, turning off is also possible during motion of the implement.
The stability of the machine in difficult terrain is guaranteed, this thanks to the small dimensions and by a sufficiently low center of gravity. An excellent maneuverability is given by the three-wheel design of the seeder / forecart assembly, which allows very sharp turns. The inner shaft width of 1000 mm assures an adequate free space for the horse during the maneuvers at the headlands. The shafts width as well as the height of the shafts carrier is adaptable to the horse’s size. By the double spring suspension of the shaft carrier, the load on the horse’s back is nearly eliminated.
As shown in summary graph 9, the previously mentioned very low draft effort on flat asphalt road increases considerably when going uphill with 9,5% slope on other tracks. Pulling the implement on the flat sand farm track to parcel C nearly triples the required draft effort compared to the flat asphalt road. The relatively high draft force on the flat dirt farm track to parcel D can be explained by the fact that the rear wheels run in deep tracks left by heavy tractor driven farm equipment. By that, the disc coulters touched the grass-covered soil in the center, requiring additional effort. A greater clearance height of the coulters in transport position would eliminate this problem.
For all executed work during this comparison test, the tractive effort for the horse can be classified as moderate, this even on fields with a terrain slope up to 8,5%. For road transport the implement requires a very low draft effort, which saves the horse’s energy for the work itself on the field. However, within this context, the considerably higher draft effort of the implement itself on worked arable land must be emphasized.
As already determined during other tests (see SmP test reports 2013 and 2014), the oscillations of the draft force increases with the effort of the horse. Related to this issue, as well as on animal welfare in general, it should be clearly pointed out the importance of further research work about the influence of different hitch, harness, and especially collar types, on the draft characteristics of draught horses.
For improving the working precision, the retrofitting of a steering device should be envisaged. This mechanism should work independently to the draft line of the horse. A modified lifting mechanism with higher ground clearance should improve the terrain suitability. Furthermore, a spring assistance of the lifting mechanism would allow the coulter’s increased contact pressure in heavier work conditions, this by maintaining at the same time a low lifting effort for the carter.
Additional tests must be conducted to determine the operational capability of this seeder concept under other ground conditions and crop residues.