Field of the invention

The present invention relates generally to sowing technology in the field of agriculture. More specifically, the present invention relates in a first aspect to a sowing apparatus and in a second aspect to use of such a sowing apparatus for sowing seeds.

Background of the invention

Within the field of agriculture, when culturing crops it is common practice to grow crops in vast areas of land for the purpose of harvesting desired parts of the crop or the whole crop itself. Due to the extremely large areas of land involved, it is preferred to use a sowing apparatus when sowing the crop seeds making the sowing process as efficient and as little time consuming as possible.

A prior art sowing apparatus is configured to be towed behind a tractor or the like, and it comprises a frame suspending on a couple of wheels. On the frame is pivotally suspended one or more shear carriers. The opposite end of each shear carrier is located near the ground and comprises a shear that during use at least is partially suspended into the soil. When towing the sowing apparatus the shears will each create a furrow in the soil, extending a relatively small distance into the soil. A seed conveyor is arranged in respect of each shear on the frame in such a way that the shear carrier allows dispensing seeds into the furrows created by the shears. By slightly angling the shears in relation to the direction of movement of the sowing apparatus, it is possible to make the shears create a furrow on the one hand, and on the other hand, immediately subsequent to dispensing and sowing a seed, to make the shears cover that furrow with soil. The covering of the furrow is made by either a second tine/share pushing soil into the furrow and/or compacting the furrow sides with a small wheel to compress soil into the furrow and make a light soil compaction around the seed to improve germination and water availability.

By burying the seeds it may be possible to establish optimum growth conditions for the seeds during the seeding stage due to the better accessibility of nutrients and water at a certain depth in the soil. Furthermore, losses of seeds to small foraging animals may be minimized and also losses due to blowing winds removing the seeds from the sowing site are avoided in this way as are detrimental effects of UV radiation originating from the sun.

Each species of crop has its own optimum conditions in relation to the initial seeding growth stage and thus also in relation to the sowing depth. Generally, the smaller the seed, the less depth of seeding desired. Furthermore, as a general rule, the smaller the seed, the more sensitive the seed will be in relation to deviations to the optimum seeding depth. Accordingly, optimum growth depth for wheat seeds is 2 - 6 cm; optimum growth depth for maize/corn seeds is 7 - 8 cm; and optimum growth depth for rape seeds is 1.5 - 2.5 cm.

When sowing a crop seed, in case a relatively large part of the seeds is seeded in a non- optimum seeding depth, a non-optimum germination of the crop will result. Due to a lower germination rate, the result will be a weaker competition against weeds and poor utilization of nutrient per area unit.

Accordingly, it is of paramount importance for the farmer's economy that the seeds will be seeded at a seeding depth which is optimum for the specific plant species. To this end, the prior art sowing apparatus is provided with a depth controlling device for attempting to secure that the seeds being seeded will be seeded at a depth which corresponds to the optimum seeing depth of the crop species in question. Such a depth controlling device comprises a spring load for spring loading the pivotally suspended shear carrier. In this way the shear carrier will not be freely movable in the pivotally suspension and it will not be rigidly suspended onto the frame of the sowing apparatus. Rather the pivotally suspended shear carriers will be pivotally suspended and forced into the soil be the force posed by the spring loading. The depth controlling device additionally comprises adjustment means for adjusting the tension of the spring, thus allowing the pivotally suspended shear carriers to be forced into the soil by a predetermined force as determined by the tension of the spring. However, although this type of prior art sowing technology provides a somewhat improved technique for sowing the crop seeds in the soil at an approximate sowing depth compared to a non-suspension system, there exist a number of disadvantages associated with this

technology.

One major disadvantage becomes apparent when using the prior art sowing apparatus in soil having a varying soil texture. Accordingly, when applying the prior art sowing apparatus in areas comprising parts of sandy soil and other parts of clayed soil, possible with areas of presence of rocks or gravel, the spring loaded shear carrier with its pre-adjusted spring tension will not be able to cope with these varying nature of soil constituents in the sense that the spring loaded shear carrier having a constant and predetermined spring tension when operating in sand, which is relatively soft, will imply that the shear will be pressed a relative deep distance into the soil, whereas when operating in clayed or rocky soil, which is relatively hard, the shear (having the same spring loading) will be pressed only a relative shallow distance into the soil.

The consequence is that the seeds are not being sown at constant depths irrespective of the nature of the soil. Hence, a non-optimum growth of crops will result.

Furthermore, as the spring load is also calibrated to a specific speed and resulting soil resistance, if the speed is varying then also the seeding depth will vary, as the soil resistance will increase commensurate with increasing speed. Especially in the case of going up and down hill, the speed can easily vary 20-40 %. Another type of depth controlling sowing machine relies on measuring the distance over ground by use of a sensor sensing the distance to the surface of the ground. The sensor may be a sonic or an optical sensor, such as an ultrasonic sensor or an IR sensor which is arranged on the sowing machine itself. In these machines the sowing depth is controlled by a control unit which regulates the sowing depth of the seeds to be sown by changing the depth of a shear submerged into the soil in response to the distance sensed by the senor.

Although these machines in theory could provide for a precise sowing depths of seeds, these machines in practice suffers from some drawbacks.

These drawbacks relate to the fact that optical and sonic sensing in general will be inaccurate and provide false reading due to temperature variation, presence of moist in the air, presence of crop residues or weed at the soil surface. Also presence of small areas of water surfaces at the upper layer of the soil may pose false readings by the sensor. Accordingly, complicated computing and noise filtering will be needed in the processing of the data originating from optical and sonic sensing. Moreover, irregular surfaces of the field may present challenges in relation to providing the correct feedback, viz. the depth of a shear submerged into the soil in response to the distance sensed by the senor.

Furthermore, dust and dirt depositing on the sensing surface of the sensor will require frequent cleaning of the sensors. Additionally, dust in the field of view might generate poor detection, impacting the sensing accuracy of optical sensing.

Finally, optical and sonic sensors are delicate equipment that needs careful maintenance in order to function properly.

Accordingly, a need persists for an improved sowing apparatus which will alleviate or even eliminate the above mentioned disadvantages.

Brief description of the invention

The object of the present invention is to alleviate or even eliminate the above mentioned disadvantages of the prior art sowing apparatus. The object of the present invention is achieved by a sowing apparatus according to claim land by the use of such a sowing apparatus according to claim 20.

Preferred embodiments of the invention are defined in the dependent claims 2 - 19.

Accordingly, the present invention relates in a first aspect to a sowing apparatus, said sowing apparatus comprises: a frame comprising a front end and a rear end, as seen in relation of the intended direction of movement; said intended direction of movement defining a longitudinal direction X of the apparatus; wherein said frame is having an extension in a transverse direction Y, said transverse direction being perpendicular to the longitudinal direction X. wherein said frame comprising one or more shear carriers, said shear carriers each having a first end and a second end; wherein said one or more shear carriers at its first end being pivotally suspended onto said frame in a suspension; wherein said shear carrier at its second end comprising one or more shears adapted to be at least partially submerged into the soil; wherein in respect of one or more of said one or more shear carriers, said frame comprising seed conveying means for conveying seeds into the soil at a position corresponding to one or more of said one or more shears; wherein in respect of one or more of said one or more shear carriers, said apparatus comprises a sensor for detecting the position of said shear carrier in relation to the frame; said sensor being configured to provide an output signal representing a sensed position of said shear carrier; wherein in respect of one or more of said one or more shear carriers said apparatus comprises an actuator for altering the position of the shear carrier in relation to the frame; wherein said apparatus comprises a control unit configured to receive said output signal from said sensor; wherein said control unit is configured to provide an output signal for controlling said actuator; wherein said control unit is connected to an input device, said input device being configured to allow an operator to provide said control unit with instruction relating to the desired response of the actuator, based the input signal of said sensor.

The present invention relates in a second aspect to use of a sowing apparatus according to the first aspect for sowing seeds.

The present invention in its first and second aspect provides for sowing crop seeds at a preferred optimum sowing depth, irrespective of the nature of the soil. Hence, more optimum growth of crops will result. The optimum sowing depth has the consequence that the crop will be more competitive against weeds and resistant towards attack from fungi in early stage and thus imply improved yield of crops. Furthermore, when sowed at an optimum depth, the crop will be more robust towards variations in weather condition.

Brief description of the figures Fig. 1 illustrates schematically the principles of a prior art sowing apparatus.

Fig. 2 illustrates schematically the principles of a sowing apparatus according to the present invention.

Fig. 3 illustrates schematically the trigonometry involved in one embodiment of the present invention.

Detailed description of the invention

The first aspect of the present invention

The present invention relates in a first aspect to a sowing apparatus 100, said sowing apparatus comprises: a frame 2 comprising a front end 4 and a rear end 6, as seen in relation of the intended direction of movement; said intended direction of movement defining a longitudinal direction X of the apparatus; wherein said frame is having an extension in a transverse direction Y, said transverse direction being perpendicular to the longitudinal direction X; wherein said frame comprising one or more shear carriers 8, said shear carriers each having a first end 10 and a second end 12; wherein said one or more shear carriers 8 at its first end being pivotally suspended onto said frame in a suspension 14; wherein said shear carrier at its second end 12 comprising one or more shears 16 adapted to be at least partially submerged into the soil 18; wherein in respect of one or more of said one or more shear carriers 8, said frame comprising seed conveying means 20 for conveying seeds into the soil at a position corresponding to one or more of said one or more shears; wherein in respect of one or more of said one or more shear carriers 8, said apparatus comprises a sensor 22 for detecting the position of said shear carrier in relation to the frame; said sensor 22 being configured to provide an output signal representing a sensed position of said shear carrier 8; wherein in respect of one or more of said one or more shear carriers said apparatus comprises an actuator 24 for altering the position of the shear carrier in relation to the frame; wherein said apparatus comprises a control unit 26 configured to receive said output signal from said sensor; wherein said control unit is configured to provide an output signal for controlling said actuator; wherein said control unit is connected to an input device 28, said input device being configured to allow an operator to provide said control unit with instruction relating to the desired response of the actuator, based the input signal of said sensor. In the present description and in the appended claims, the term "intended direction of movement" shall be construed to mean "the direction of movement of the sowing apparatus when used for sowing", wherein the shears are usually positioned at a relatively rear position.

In the present description and in the appended claims, the term "the position of the shear carrier in relation to the frame" shall be construed to mean "the position of the shear carrier, in a vertical direction, in relation to the frame".

In one embodiment of the first aspect of the present invention, in respect of one or more of said one or more shear carriers 8, said seed conveying means 20 for conveying seeds into the soil at a position corresponding to one or more of said one or more shears comprises a tube or pipe 21 having an extension in a vertical direction from an inlet opening 28 thereof to an outlet opening 30 thereof, said outlet opening 30 being arranged below said inlet opening 28.

In one embodiment of the first aspect of the present invention, in respect of one or more of said one or more shear carriers 8, said seed conveying means 20 for conveying seeds into the soil at a position corresponding to one or more of said one or more shears are configured to conveying seeds into the soil at a position corresponding to a rear part 32 of one or more of said one or more shears

Such arrangements provide for a cost efficient and simple way of conveying seeds into the soil.

In one embodiment of the first aspect of the present invention in respect of one or more of said one or more shear carriers 8 said seed conveying means 20 for conveying seeds into the soil at a position corresponding to one or more of said one or more shears is connected to a seed dispensing device 34 for dispensing seeds at a predetermined intervals.

This ensures an automated dispensing of seeds into the soil and thus may provide an accurate and constant mutual distance of sown seeds. In one embodiment of the first aspect of the present invention said frame 2 comprises one or more wheels or carrier rollers 36 for providing support for said frame when towing the apparatus.

Providing the sowing apparatus with wheels or carrier rollers ensures less resistance when towing the apparatus behind a tractor. Furthermore, this may provide more accurately seeding seeds at a predetermined sowing depth.

In one embodiment of the first aspect of the present invention said sensor 22 and said actuator 24 is an integrated unit 38.

Such an arrangement provides a more simple design of the sowing apparatus.

In one embodiment of the first aspect of the present invention said control unit 26 is configured to receive instructions relating to a desired basis-depth of sowing, thus

corresponding to a desired basis-position of the actuator relative to the frame.

Hereby is ensured that when sowing seeds, the seeds will as far as possible be sown at this predetermined basis-depth of sowing.

In the present description and in the appended claims, the term "basis-depth" shall be construed to mean a desired and optimum sowing depth associated with the specific crop species to be grown. The actual sowing depth may undesirably deviate from this basis-depth due to various types of errors or difficult soil conditions. However, the basis-depth is the depth at which it is desired that the seeds are to be sown.

In one embodiment of the first aspect of the present invention said sensor 22 being a sensor configured to sense a translational displacement; or wherein said sensor 22 being a sensor configured to sense an angular displacement.

These two types of sensors both will provide accurate sensing of the movement of the shear carriers in relation to the frame. In one embodiment of the first aspect of the present invention the number of shear carriers is 5 - 180 or more, such as 10 - 175, e.g. 15 - 170, such as 20 - 165, e.g. 25 - 160, such as 30 - 155, e.g. 35 - 150, such as 40 - 145, such as 45 - 140, for example 50 - 135 or 55 - 130, such as 60 - 125, e.g. 65 - 120, such as 70 - 115, e.g. 75 - 110, for example 80 - 105, such as 85 - 100, such as 90 - 95.

Such numbers of shear carriers will provide for a fast and efficient sowing of crop seeds.

In one embodiment of the first aspect of the present invention, in respect of one or more of said one or more shear carriers said shear carrier may independently comprise one, two or three or more shears. It may in certain cases not be necessary for each shear to have its own associated shear carrier. Providing one or more shear carriers with more shears provides for construction savings and a simpler design.

Likewise it may in certain cases not be necessary for each shear carrier to have its own associated actuator and/or have its own associated sensor. Accordingly, groups of two, three, four or more shear carriers, preferably shear carriers located in an immediate vicinity of each other, may be configured to forced synchronous movement, e.g. by being welded together, in a configuration where these groups of two, three, four or more shear carriers are sharing the same common actuator and/or the same common sensor.

Similarly, it is understood that within the meaning of the present description and the appended claims, the sowing apparatus of the first aspect of the present invention may one or more control units. Accordingly, one control unit may be configured to provide output signals for controlling all the actuators comprised in the sowing apparatus.

In one embodiment of the first aspect of the present invention the sowing apparatus being configured to be towed behind a tractor or the like. In another embodiment of the first aspect of the present invention, the sowing apparatus being a self-propelled sowing apparatus.

In one embodiment of the first aspect of the present invention it is a requirement that in respect of one or more of said one or more shear carriers said apparatus comprises a spring, such as a pressure spring; said spring being suspended in serial configuration in relation to said actuator. Hereby is achieved that shear carried being suspended in such a way that the actuator adjusts the tension of the spring load of the shear carrier.

In one embodiment of the first aspect of the present invention it is a requirement that in respect of one or more of said one or more shear carriers, said one or more shears being a drill shear or a disc shear.

Such types of shears are traditionally and conventionally used as shears in sowing

apparatuses.

In one embodiment of the first aspect of the present invention, said sowing apparatus does not comprise a sonic or an optical sensor for remote sensing a distance. In the present description and in the appended claims the term "remote sensing a distance" shall be interpreted as a situation in which a sensor senses a distance through the air. Hence, the term "remote sensing a distance" implies that the distance is sensed by the sensor without "touching". In one embodiment of the first aspect of the present invention said sowing apparatus does not comprise an optical or sonic sensor. In one embodiment of the first aspect of the present invention said sowing apparatus does not comprise an optical or sonic sensor for sensing a distance from said sensor to the surface of the ground.

In one embodiment of the first aspect of the present invention said sowing apparatus does not comprise an optical or sonic sensor, such as an ultrasound sensor or an infrared sensor. In one embodiment of the first aspect of the present invention it is a requirement that in respect of one or more of said one or more shear carriers, preferably all said shear carriers, said control unit is configured to dynamically regulating said output signal for controlling said actuator, solely in response to the output signal originating from said sensor.

In one embodiment of this embodiment of the first aspect of the present invention it is a requirement that in respect of one or more of said one or more shear carriers, preferably all said shear carriers, said control unit is configured to dynamically regulating said output signal for controlling said actuator; without receiving input from any other type of sensor as defined above. These embodiments avoids the disadvantages associated with using optical or sonic sensors for sensing a distance of a frame of a sowing apparatus over the ground as set out in the introduction of the present application.

In the present description and the appended claims the term "dynamically regulating" shall be interpreted as a repeatedly adjustment of the position of the shear carrier in relation to the frame based on the position of the shear carrier as detected by the sensor.

Accordingly the term "dynamically regulating" is different from an initial setting of the control unit relating to a desired "basis depth" which in turn in most situations will be a single adjustment of the control unit and relating to a specific species of crop.

The second aspect of the present invention

The present invention relates in a second aspect to the use of a sowing apparatus according to the first aspect for sowing seeds.

Referring now in details to the drawings for the purpose of illustrating preferred embodiments of the present invention, fig. 1 illustrates schematically the principle of a prior art sowing apparatus. Fig. 1 shows the prior art sowing apparatus 200 comprising a frame 2 to be towed along a longitudinal direction X at a towing part (not shown in fig. 1). The frame is suspended on wheels or carrier rollers 36 which allow the frame to follow the surface of the soil 18 when being towed. On the frame 2 is pivotally suspended a shear carrier 8 having a first end 10 and a second end 12. The shear carrier is suspended onto the frame 2 at its first end 10 in a suspension 14. At the second end 12 of the shear carrier 8 is ratably mounted a shear 16. The shear carrier 8 is in relation to the frame 2 subjected to the action of a spring 202 which will force the shear carrier 8 downward in relation to the frame 2 by pivoting in the suspension 14. A spring tensioner 204 allows for adjusting the tension of the spring 202, thus resulting in varying the force with which the shear carrier 8 is forced downward, and thus varying the force with which the shear 16 is forced into the soil. This feature in turn results in allowing adjustment of the depth of the shear furrow, and thus ultimately the depth at which the seeds will be sowed. The seeds to be sown originates from a seed hopper (not shown in fig. 1) and passed a seed dispensing device 34 (also not shown in fig. 1) before it is allowed to be guided into the soil via seed conveying means 20 in the form of a pipe 21 having an inlet opening 28 at an upper part and an outlet opening 30 at a lower part.

As it can easily be contemplated from the schematically outline of the principle of the prior art sowing apparatus of fig. 1, the apparatus when towed in use and upon being set with a predetermined spring tension by adjusting spring tensioner 204, will allow the shear carrier 8 to pivot around the suspension 14 at a varying angle, thus resulting in a varying shear depths D and thus varying sowing depth of the seeds.

Accordingly, the prior art apparatus as outlined in fig. 1 does not provide for optimum sowing depths of seeds, and consequently ultimately results in a non-optimum quantity and quality of harvested crops.

Parameters especially affecting the sowing depths of seeds with the prior art apparatus of fig. 1 are the texture or nature of the ground or soil, such as type of soil (e.g. soil constituents like clay, sand, gravel), moisture content of soil, presence of plant residues in the soil, presence of rocks in the soil.

The disadvantages of the prior art sowing apparatus of fig. 1 has been overcome with a sowing apparatus according to the present invention. Such an apparatus is shown in fig. 2.

Fig. 2 illustrates a sowing apparatus 100 according to a first aspect of the present invention. The sowing apparatus 100 comprising a frame 2 to be towed along a longitudinal direction X at a towing part (not shown in fig. 2). The frame is suspended on wheels or carrier rollers 36 which allow the frame to follow the surface of the soil 18 when being towed. On the frame 2 is pivotally suspended a shear carrier 8 having a first end 10 and a second end 12. The shear carrier is suspended onto the frame 2 at its first end 10 in a suspension 14. At the second end 12 of the shear carrier 8 is ratably mounted a shear 16.

The seeds to be sown originates from a seed hopper (not shown in fig. 2) and passed a seed dispensing device 34 (also not shown in fig. 2) before it is allowed to be guided into the soil via seed conveying means 20 in the form of a pipe 21 having an inlet opening 28 at an upper part and an outlet opening 30 at a lower part.

Seed hoppers and seed dispensers suitable for use in the present invention are readily available on the marked and are thoroughly disclosed in the prior art. Examples of such devises may be found by reference to the producers Kvernland Accord, Pottinger, Kongskilde, Kuhn and Lemken.

Between the shear carrier 8 and the frame 2 is arranged a sensor 22, sensing the angle a between the shear carrier 8 and the frame 2. Alternatively, the sensor 22 may be configured for sensing not an angular displacement but rather a translational displacement between the shear carrier 8 and the frame 2. Also arranged between shear carrier 8 and the frame 2 is an actuator 24 for actuating or asserting a force between the shear carrier 8 and the frame 2. Such actuation will result in moving the pivotally suspended shear carrier 8 in relation to the frame 2 by rotational movement in the suspension 14. Accordingly, by means of the actuator 24, the shear carrier 8 may be lifted upward in a direction away from the ground or soil; or may be forced downward in a direction towards the ground or soil, thereby altering the angle a between the shear carrier 8 and the frame 2. The actuator 24 may e.g. be a hydraulic actuator, an electrical actuator or a mechanical actuator.

In this way the depth D of the shear furrow created by the shear 16 may be adjusted.

Accordingly, ultimately this allows for adjustment of the depth at which the seeds will be sown.

The sowing apparatus according to the first aspect also comprises a control unit 26 (not shown in fig. 2). The control unit 26 is configured to receive input signal originating from the sensor 22. Furthermore, the control unit is configured to send instruction signals to the actuator.

Preferably, the control unit 26 comprises means, such as a data storage medium, comprising a computer program which provides instructions as to how the actuator 24 must react on the basis of input signals received form the sensor 22.

Preferably, the control unit 26 comprises input means for allowing an operator to input data relating to the desired behavior of the actuator 24 in response to signals received form the sensor 22. Such input means may be in the form of a keyboard. Additionally, the control unit 26 may include a monitor or the like for allowing an operator to monitor the settings of the control unit and/or the operation of the seeding apparatus.

In this way, the control unit 26 may be configured to receive instructions relating to a desired basis-depth of sowing, thus corresponding to a desired basis-position of the actuator relative to the frame. The term "basis depth" shall in the present description and in the appended claims be construed to mean a predetermined sowing depth of a specific crop species which has shown to be optimum in respect of that crop species.

The sensor 22 and the actuator 24 may be in the form of an integrated unit 38. Such integrated units are commercially available. Accordingly, the producer Biiter manufactures hydraulic cylinders with build in electronic sensors.

Whether being separate units or an integrated unit it is desired that the actuator 24 is being suspended between the 2 frame and the shear carrier 8 in series with a spring, such as a pressure spring for providing a spring loaded shear carried in such a way that actuator 24 adjusts the tension of the spring load of the shear carrier.

In fig. 2 only principles of the sowing apparatus according to the first aspect of the invention have been depicted. It should be noted, however, that while fig. 2 only illustrates a sowing apparatus having one shear carrier 8 and one shear 16 and one seed conveying means 20, it will easily be contemplated that the inventive apparatus may comprise a number of such shear carriers, shears and seed conveying means. Such shear carriers, shears and seed conveying means will typically be arranged "in-line" in a transverse direction Y, perpendicular to the intended direction of movement of the sowing apparatus. For example, the inventive sowing apparatus may comprise 5 - 180 or more, such as 10 - 175, e.g. 15 - 170, such as 20 - 165, e.g. 25 - 160, such as 30 - 155, e.g. 35 - 150, such as 40 - 145, such as 45 - 140, for example 50 - 135 or 55 - 130, such as 60 - 125, e.g. 65 - 120, such as 70 - 115, e.g. 75 -

110, for example 80 - 105, such as 85 - 100, such as 90 - 95 shear carriers. Each shear carrier may comprise one, two or three or even more shears. The number of seed conveying means may typically be identical to the number of shears.

Accordingly, the inventive sowing apparatus as outlined in fig. 2 allows for providing optimum sowing depths of seeds, because the sensor 22 and the actuator 24 constantly will be sensing the depth of the shear and subsequently and immediately thereafter dynamically adjust the depth of the shear if that depth is deviating from a predetermined and desired depth of sowing, such as a "basis depth".

Consequently, the inventive sowing apparatus provides for optimum quantity and quality of harvested crops. This is not at least the case when using the inventive sowing apparatus in soil having a varying texture or nature as to content, such as sand, clay, rocks, plant residues etc. Fig. 3 illustrates the trigonometry involved in converting the angle a between the frame 2 and the shear carrier 8 as outlined in fig. 2, to a sowing depth D.

Fig. 3 illustrates in a simplified way the frame part 2 of the sowing apparatus according to the first aspect of the present invention. The frame part 2 is oriented in a horizontal direction parallel to the longitudinal direction of the intended movement of the apparatus during use.

On the frame part 2 is in suspension 14 pivotally suspended the shear carrier 8 having the length L (between the pivot point 14 and the mounting point of the shear). The frame part 2 and its pivot point 14 is arranged at a height H above the surface of the ground.

The radius of the shear is R, and the shear is at the angle a between the frame 2 and the shear carrier 8 submerged the distance D into the soil.

One easily deduces that: h = L x sin(a); and h + R = H + D; which gives the correlation: D = L x sin(a) + R - H; h being the vertical distance from the pivot point of the shear carrier to the mounting point of the shear.

Accordingly, knowing the radius R of the shear 16; the effective length L of the shear carrier 8; the height H above ground of the frame part 2 (or its pivot point 14); and the measured or sensed angle a, allow one to calculate the sowing depth D.

These parameters may accordingly be useful in programming or setting the control unit 26 in order to obtain an optimum sowing depth.

In fig. 1, 2 and 3, the shear is depicted as a disc -type shear. However, any other type of conventional and/or traditional shear may be used with the sowing apparatus according to the first aspect of the present invention. Above only a few embodiments of the invention have been described, however, it can easily be envisaged that several other embodiments are possible within the scope of the invention as defined in the claims.

List of reference numerals

2 Frame of sowing apparatus

4 Front end of frame

6 Rear end of frame

8 Shear carrier

10 First end of shear carrier

12 Second end of shear carrier

14 Suspension of shear carrier

16 Shear

18 Soil

20 Seed conveying means

21 Tube or pipe

22 Sensor

24 Actuator

26 Control unit

28 Inlet opening of tube or pipe

30 Outlet opening of tube or pipe

32 Rear part of shear

34 Seed dispensing device

36 Wheel or carrier roller of sowing apparatus

38 Integrated sensor/actuator

40 Input device h Vertical distance from pivot point of shear carrier to the mounting point of shear.

H Height above ground of pivotally suspension of shear carrier

R Radius of shear

L Effective length L of shear carrier

D Depth of shear furrow

a Sensed angle between shear carrier and frame part

100 Sowing apparatus according to the present invention

200 Prior art sowing apparatus

202 Spring

204 Spring tensioner