GB1588532A

GB1588532A - Seed drills

Info

Publication number: GB1588532A
Application number: GB1204977A
Authority: GB
Original assignee: National Research Development Corp UK; National Research Development Corp of India
Current assignee: National Research Development Corp UK; National Research Development Corp of India
Priority date: 1977-03-22
Filing date: 1977-03-22
Publication date: 1981-04-23
Also published as: AU3429778A; NZ186753A; FR2384436A1

Description

(54) IMPROVEMENTS IN AND RELATING TO SEED DRILLS (71) We, NATIONAL RESEARCH DE VELOPMENT CORPORATION, a British Corporation established by Statute, of Kingsgate House, 66-74 Victoria Street, London, S.W.1, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to improvements in and relating to seed drills.

In recent years a method of drilling seeds has come into use in which seeds are drilled directly into the soil after a suitable-slit- like furrow has been opened for the seeds without any prior preparation of the land by ploughing, harrowing or the like. Such a method has become known as direct drilling, and the drill most commonly used for direct drilling has been a drill known as the triple disc drill. In this apparatus a frame drawn behind a tractor is mounted on two side land wheels and comprises a transverse array of drill units, for example fifteen drill units. Each drill unit comprises a leading single rotatable disc which cuts a slit in the soil, followed by a pair of flat discs, facing each other in register with the flat sides facing each other, which open out the previously cut slit. Between the pair of discs a seed boot feeds seed into the opened slit, and the slit is commonly covered by a trailing harrow following the seed drill.

In order to arnange for the leading disc to cut the required slit, and for the following pair of discs to open the slit, the drill units are urged downwardly by compression springs operating between the drill units and the main frame of the drill. In order to allow for undulations in the soil between the two land wheels, each drill unit is mounted by individual mounting means to allow substantially vertical movement of the drill unit relative to the frame.

According to the present invention, there is provided a seed drill comprising a frame for movement over the soil, a rotatable disc for cutting a slit-like furrow in the soil, seed conduit for delivering seed to that part of the furrow adjacent the cutting disc at the time of seed delivery, elongate mounting means pivoted at its leading end to the frame and with the cutting disc mounted at its trailing end thereby to allow substantially vertical movement of the disc relative to the frame, means for urging the disc downwardly relative to the frame, and a skid fixed rel;ative to the rotation axis of the disc and having a contact portion substantially confined to the vicinity of the cutting disc and adapted to rest on and slide over the soil thereby to limit the depth and pentration of the disc into the soil.

By substantially vertical movement of the disc relative to the frame is meant a movement of the disc relative to the frame having a substantial vertical component of motion when the frame is in normal operating position on horizontal ground. Preferably the mounting means is adapted to lallow pivotal movement of the disc relative to the frame about a pivot point spaced from the disc by a distance substantially greater than the distance of substantially vertical movement allowed by the mounting means.

Preferably the seed conduit is coupled to a seed outlet means mounted on the said mounting means adjacent the said disc. Also preferably the depth limiting element is fixed in normal operation relative to the axis of rotation of the cutting disc !and is coupled to the mounting means to move relative to the frame with movement of the cutting disc. It is preferred that the depth limiting element is positioned alongside the cutting disc at a height above the bottom of the cutting disc by an amount equal to the desired depth of cutting of the cutting disc.

In a preferred arrangement according to the invention, the depth skid comprises a lead-in portion comprising an elongated guide member of greater length than said contact portion of the skid, the elongated guide member leading from the contact portion forwardly and upwardly relative to the direction of movement of the frame.

Where the mounting means comprises an elongated mounting member as set out above, preferably the depth skid has its contact portion at the rear of the elongated mounting member and is fastened to the elongated mounting member at the forward upper end of the lead-in portion of the depth skid. Conveniently, the junction of the forward portion of the depth skid with the mounting member is in the region of the pivot of the elongated member on the frame, the contact portion of the depth skid being at the trailing end of the elongated mounting member and therebelow.

According to a preferred feature of the invention, the depth limiting element may be provided with a delfector plate inclined to the horizontal and positioned closely adjacent the cutting disc, the deflector plate being arranged in a position such that in operation seed delivered by the seed conduit strikes the deflector plate and is deflected sideways into the furrow cut by the disc. Preferably the said inclined deflector plate is inclined at an angle lying in the range 450 to 800 to the horizontal, most preferably in the range 600 to 700.

Where the depth limiting element is a depth skid as set out above the said deflector plate conveniently comprises an upstanding plate mounted on the said contact portion of the depth skid.

Preferably the cutting disc comprises a dish shaped disc, and most preferably, the depth limiting element is positioned on the convex side of the said dished disc. The axis of rotation of the cutting disc may be inclined to the horizontal with the concave side of the disc facing downwardly, and the angle of inclination of the axis to the horizontal is preferably in the range 0-10 degrees, most preferably substantially 40.

Also preferably the axis of rotation of the cutting disc is inclined at an angle to a transverse axis of the frame. By a transverse axis of the frame is meant a direction perpendicular to the direction of intended forward travel of the machine. Preferably the angle of inclination of the axis of rotation of the cutting disc to the transverse axis of the frame is in the range 3 to 100, preferably substantially 60.

Conveniently the means for urging the disc downwardly may comprise a compression spring individual to the cutting disc.

Where the mounting means comprises an elongated mounting member, the compression spring may conveniently act between the trailing end of the mounting member and the frame.

Conveniently the frame comprises a tractor drawn frame mounted on two side wheels. Preferably the frame carries a plurality of rotatable cutting discs arranged in a transverse array across the line of travel of the frame, each disc having a mounting means individual thereto and a seed conduit individual thereto.

Conveniently the seed conduit of each cutting disc may comprise a flexible conduit leading from a common seed hopper to a seed outlet means individual to the cutting disc and mounted for movement relative to the frame with the cutting disc.

Preferably the depth skid is as wide as possible having regard to the positioning of adjacent cutting discs, and preferably is no less than two inches wide taken in a direction generally transverse to the direction of forward travel of the frame.

Conveniently there may be provided a second conduit leading to the slit cut by the cutting disc from a separate hopper adapted to deliver fertiliser to the soil together with the seeds.

Embodiments of the present invention can be arranged to provide advantages relative to known direct drills, and in particular relative to the triple disc drill described above.

A major requirement of any seed drill used for direct drilling is that the drill shall plant the seed at a uniform depth below the surface of the soil. Typically this depth is required to be in the range of -2't to 2 Typically the required depth may be 12" and should vary on either side of this required depth by no more than half an inch.

Because the seeds are drilled directly into an unprepared soil surface, this soil surface will commonly vary throughout the field to be drilled. If in a known triple disc drill the downward force urging the discs into the soil is set to be correct for normal fairly compacted soil, i.e. the force is set so that the discs penetrate the required depth in normal soil, variation of the depth cut will occur in different parts of the field where the surface varies. For example where the soil is looser the discs will tend to dig in too deeply, and where the land has a surface mat of grass or other material the discs will tend to ride over the top without penetrating the soil at all.

A further cause of variations in penetratration in a known triple disc drill arises where undulations occur between the land wheels of the seed drill. As the drill unit rides up over the undulation the compression spring operating on the unit is compressed so that the downward force increases. Thus as a drill unit rides over a raised portion of ground the discs will be forced to dig deeper into the raised portion.

Conversely where a unit rides down into a dip, lesser penetration will occur.

Another disadvantage which occurs with the particular example of direct drill described above and referred to as the triple disc drill is that the trailing pair of discs tend to smear the sides of the slit cut by the leading disc which can make it difficult for newly germinated seeds to penetrate the walls of the slit by their roots. Another disadvantage is that the front disc has a tendency to bury in the slot any loose straw or other organic material lying on the soil surface. This material buried in the slit tends to rot and decay and release toxic materials which can kill or inhibit growth of the germinating seeds. Fflrthermore smearing can produce water logging of the soil as water tends to collect in the slits exacerbating the problem of rotting straw which has been forced into the slit with the seed.

In contrast sertain embdim nts of the present invention can be arranged to eliminate or reduce the effects of the disadvantages set out above. In particular the use of a depth limiting element in accordance with the present invention allows the dept of furrow cut by the cutting disc to be main- tained substantially constant. In operation the downward force on the cutting disc is adjusted to be sufficient to cut the required furrow in the most adverse conditions, and the depth limiting element act to prevent too deep a furrow being cut when the device operates over soil conditions less difficult to penetrate. The use of a single disc has the advantages that there is less smearing of the furrow cut, and also there is less tendency for straw to be buried in the furrow.

In one modification of the arrangement of the depth limiting means, there is provided a depth skid having two ground-contact portions positioned one on either side of the cutting disc. Preferably the ground contact portions contact the ground in a position slightly ahead of the penetration of the ground by the cutting disc. The purpose of this arrangement is to hold straw and like matter material taut in the path of the cutting disc so that the cutting disc cuts through the straw rather than pushing the straw down into the slit-like furrow cut by the disc.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective view of la seed drill embodying the invention looking slightly to the rear relative to the intended direction of forward travel of the implement; Figure 2 is a perspective view, looking to the rear, of two drill units embodying the invention and forming part of an array of drill units provided in the seed drill shown in Figure 1, the drill units shown in Figure 2 forming part of the right hand half of the array of drill units as seen in Figure 1; Figure 3 is a side view of a drill unit embodying the invention and forming part of the left hand half of the array of drill units as seen in Figure 1; Figures 3(a) and 3(b) show a modilt cation of a height adjustment means shown in Figure 3; and Figure 4 is a plan view of the drill unit shown in Figure 3; and Figure 5 is a rear view of the drill unit shown in Figure 4.

In Figure 1 there is shown seed drill embodying the present invention and suitable for direct drilling, that is to say drilling into soil which need not have been prepiously prepared by ploughing. The seed drill comprises a main frame 11 drawn by a tractor (the rear wheels of which are indicated at 12) by a convenient draw bar 13.

The frame 11 is mourited on a pair of land wheels 14.

The frame 11 carries sixteen drill units each of which is indicated generally by the reference numeral 15. Each drill unit 15 comprises a cutting disc 16, a seed outlet means 17 and mounting means comprising an elongated mounting member 18 pivoted to the main frame 11 at a pivot 19. The details of each seed unit 15 will be described in more detail hereinafter with reference t6 Figures 3, 4 and 5.

Each drill unit 15 is provided with means for urging the drill unit downwardly relative to the frame 11, the urging means comprising a compression spring 20 individual to the drill unit. Each spring 20 is coupled between a strut 21 upstanding from the elongated member 18, and the frame 11 by way of a common cross-member 22 which is pivotally coupled to the main frame 11 at pivots 23. The position of the cross-member 22 relative to the frame 11 is controlled by a hydraulic ram 24 acting between the base of the main frame 11 and a fixture 25 fixed relative to the cross-member 22. The springs 20 are counterbalanced by tension springs 26 coupled between arms 27 fixed relative to the cross-member 22, and the main frame 11.

The arrangement of the spring system described is arranged to be such that during transportation before normal operation, the hydraulic ram 24 is relaxed allowing the tension springs 26 to lift the cross-member 22 so as to raise the drill units 15 about their pivots 19 clear of the ground. When it is desired to operate the drill, the ram 24 is expanded against the tension springs 26 and the cross-member 22 is forced downwardly so that the springs 20 compress and apply a downward pressure on the drill units 15.

The downward pressure on the drill units 15 can be selected by variation of the pressure on the ram 24, the mounting points of the ram 24 on the member 25, and the rating of the springs 20.

Mounted on the upper part of the frame 11 is a hopper 28 of conventional design which is partitioned into two compartments for seed and fertiliser, the seed and fertiliser being fed to each drill unit 15 along a pair of conduits 29 and 30-individual to the seed unit 15. The seed conduit is indicated at 30 and the fertiliser conduit at 29.

Referring now in particular to Figures 3, 4 and 5 there will be described a single drill unit, the other drill units being similar except that the attitude of the discs is reversed between the two sides of the drill frame 11.

The cutting disc 16 comprises a single dish shaped, concave disc 16 mounted for free rotation on a bearing 31 which in turn is secured to the elongated member 18 by a bolt 32. The axis 46 of rotation of the disc 16 is arranged to be inclined both to the horizontal, and to the general transverse axis of the main frame 11. Thus the axis 46 of the disc 16 is inclined to the axis of rotation of the side land wheels 14. This angle of inclination is indicated at ,oe in Figure 3 and may conveniently be equal to 60. Preferably the angle of inclination los of the axis 46 lies in the range 5 to 100. The axis 46 of rotation of the disc 16 is also inclined to the horizontal in !a sense such that the concave face of the disc is inclined slightly downwardly. The angle of inclination of the axis 46 to the horizontal is preferably in the range 0 to 100 and conveniently may be equal to 40.

The elongated mernber 18 also supports a seed outlet means 17. There may also be provided one or more scrapers for the disc 16 but these are omitted from the drawings for simplicity.

As shown particularly in Figure 3, there extends downwardly from the forward end of the elongated member 18 a depth skid 36 comprising a ground-contact portion 37 which contacts the ground in the vicinity of the bottom of the disc 16, and a lead-in portion 38 which rises forwardly and upwardly from the ground contact portion 37 to a pair of bolts 39 and 40 which secure the skid 36 to the elongated member 18. Coupled between the depth skid 36 (in the region of the ground contact portion 37) and the elongated member 18 is a jack 41 providing an adjustment of the height of the ground contact portion 37 of the skid 36 relative to the bottom of the wheel 16. The bottle jack comprises an inner strut 42 which may be moved relative to an outer sleeve 43 by adjustment of a nut 44 and a lock nut 45.

Adjustment of the height of the depth skid 36 is achieved by slight bending of the long lead-in portion 38 which conveniently is formed of spring steel.

A modification which may be made to the arrangement shown in Figure 3 is the replacement of the bottle jack 41 by an adjustable strut shown at 51 in Figures 3(a) and 3(b). The strut 51 is coupled to the skid 36 by a ball and socket coupling 52, and is coupled to the member 18 by passing through a transverse rod 53 which is pivotally mounted in two parallel side flanges of which one is shown at 54. The upper part of the strut 51 is threaded, as is the aperture in the transverse rod 53 through which the strut 51 is passed. The top of the strut 51 carries a square end 55 to enable the strut 51 to be rotated by a spanner. Rotation of the strut 51 drives the strut through the threaded aperture in the transverse rod 53 which varies the effective length of the strut 51 between the skid 36 and the member 18.

In accordance with a preferred feature of the invention there is provided, as shown in Figures 3, 4 and 5, a deflector plate 60 mounted on the contact portion 37 of the depth skid 36. The deflector plate 60 is inclined to the horizontal and is positioned closely adjacent the cutting disc 16 in a position such that seed delivered by the seed conduit 30 and passing through the seed outlet means 17 strikes the deflector plate 60 and is deflected sideways into the furrow cut by the disc 16. As shown, the deflector plate 60 is positioned on the convex side of the disc 16. The object of the deflector plate 60 is to prevent seed from spilling sideways on to the soil surface and missing the slit-like furrow. Preferably the deflector plate 60 is inclined to the horizontal at an angle in the range 450 to 800, most preferably in the range 60 to 70".

In operation as the main frame 11 is drawn forwardly by the tractor and the drill units 15 are urged downwardly by the springs 20, the discs 16 cut in the soil narrow slit-like furrows into which are dropper seed and fertiliser from the seed boot 17. The seed and fertiliser is metered into the conduits 30 and 29 by a metering roller of conventional design in the base of the hopper and not shown in the drawings.

A first advantage of the embodiment described is that the depth of penetration of the discs 16 can be controlled by the depth skids 36. The pressure applied by the springs 20 is arranged to be at least equal to the force required to penetrate the soil in most disadvantageous soil conditions, for example when there is a surface mat of grass or straw. In these conditions most of the force is carried on the disc 16 which penetrates the soil, and little of the downward force is carried on the depth skid 36. When the discs 16 meet looser soil the disc penetrates the soil easily, but does not penetrate to a great depth because the excess force of the springs 20 is carried on the ground contact portion 37 of the depth skid 38.

Another feature of the embodiment of the invention described is that when the frame 11 passes over ground with undulations between the wheels 14, and one or more of the drill units 15 rises up over a bump in the ground, the increased force applied to the disc 16 by virtue of the compressed spring 20 does not result in further peneration of the soil, because the skid depth 36 takes the additional force rather than the additional force passing to the disc 16.

By way of example of dimensions of the structural elements in the embodiment described, the following dimensions may be used: Dise diameter ... ... ... ... 18 inches Length of elongated member 18 ... ... 37 inches Distance between axis of pivot 19 and axis 46 of rotation disc 16 Length of lead-in portion 38 of depth skid 36 ... .., .., ... ... 22 inches (approx.) Length of ground contact portion 37 of depth skid 36 ... ... ... ... 6 inches (approx.) Width of depth skid 36 in horizontal plane ... ... ... ... ... 2 inches (approx. or greater) Suitable land speed of implement during drilling .. ... ... 2 to 8 m.p.h.

The downward pressure exerted by the springs 20 on the drill units 15 for normal ground may be selected in the range 10 to 300 lbs, although for difficult ground positions this may be increased.

One feature of the seed drill described in accordance with the present invention is that the skewed concave disc cuts the required slit-like furrow, but also produces some flurry of soil by virtue of its skew angle of rotation, and produces some disturbance of the soil pan. Previously it had been supposed to be advantageous to main- tain the disturbance of the soil surface to a minimum and this was one object of the triple disc direct drill. The reason for this was that it has been thought that minimum disturbance would reduce weed growth.

However it has now been found that some disturbance of the soil surface gives better yields, so that the slight disturbance produced by the single disc of the present invention is advantageous. Typically a triple disc leaves intact a surface cap from which water runs into the slit-like furrow and tends to rot the seed. With embodiments of the present invention the flurry of soil disturbance produced reduces the likelihood of localised water-logging and the chances of seed rot.

This feature is assisted by the fact that the single disc of the present invention reduces smearing in that only one side of the groove can be smeared by the disc. Reduced smearing allows easier penetration of the walls of the slit by the roots of newly germinated seeds.

A further advantage of the present invention is that the mechanism is simpler since only a single disc need be used for each drill unit. This also gives less likelihood of blocking by surface trash.

A feature of some embodiments of the present invention is the provision of a relatively long lead-in portion of the depth skid 36 in order to reduce the possibility of blocking of the depth skid by surface trash The long gentle inclination of the lead-in portion 38 enables the depth skid to deal more easily with surface trash. Furthermore because of the greater force which can be applied to each disc without fear of over penetration, the discs are more easily able to cut through surface trash such as straw rather than burying the straw in the slits.

Finally there may be provided a modification (not shown) of the depth skid shown in Figure 4 in which the skid is formed with two ground contact portions positioned one on each side of the disc 16. Preferably in such a case the ground-contact portions of the depth skid are positioned slightly forwardly of the lowest portion of the disc 16, so that any surface trash such as straw is held taut on the ground just before the disc meets the straw, with the result that the disc more easily cuts the straw rather than burying it in the slit.

WHAT WE CLAIM IS:- 1. A seed drill comprising a frame for movement over the soil, a rotatable disc for cutting a slit-like furrow in the soil, seed conduit for delivering seed to that part of the furrow adjacent the cutting disc at the time of seed delivery, elongate mounting means pivoted at its leading end to the frame and with the cutting disc mounted at its trailing end thereby to allow substantially vertical movement of the disc relative

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Another feature of the embodiment of the invention described is that when the frame 11 passes over ground with undulations between the wheels 14, and one or more of the drill units 15 rises up over a bump in the ground, the increased force applied to the disc 16 by virtue of the compressed spring 20 does not result in further peneration of the soil, because the skid depth 36 takes the additional force rather than the additional force passing to the disc 16. By way of example of dimensions of the structural elements in the embodiment described, the following dimensions may be used: Dise diameter ... ... ... ... 18 inches Length of elongated member 18 ... ... 37 inches Distance between axis of pivot 19 and axis 46 of rotation disc 16 Length of lead-in portion 38 of depth skid 36 ... .., .., ... ... 22 inches (approx.) Length of ground contact portion 37 of depth skid 36 ... ... ... ... 6 inches (approx.) Width of depth skid 36 in horizontal plane ... ... ... ... ... 2 inches (approx. or greater) Suitable land speed of implement during drilling .. ... ... 2 to 8 m.p.h. The downward pressure exerted by the springs 20 on the drill units 15 for normal ground may be selected in the range 10 to 300 lbs, although for difficult ground positions this may be increased. One feature of the seed drill described in accordance with the present invention is that the skewed concave disc cuts the required slit-like furrow, but also produces some flurry of soil by virtue of its skew angle of rotation, and produces some disturbance of the soil pan. Previously it had been supposed to be advantageous to main- tain the disturbance of the soil surface to a minimum and this was one object of the triple disc direct drill. The reason for this was that it has been thought that minimum disturbance would reduce weed growth. However it has now been found that some disturbance of the soil surface gives better yields, so that the slight disturbance produced by the single disc of the present invention is advantageous. Typically a triple disc leaves intact a surface cap from which water runs into the slit-like furrow and tends to rot the seed. With embodiments of the present invention the flurry of soil disturbance produced reduces the likelihood of localised water-logging and the chances of seed rot. This feature is assisted by the fact that the single disc of the present invention reduces smearing in that only one side of the groove can be smeared by the disc. Reduced smearing allows easier penetration of the walls of the slit by the roots of newly germinated seeds. A further advantage of the present invention is that the mechanism is simpler since only a single disc need be used for each drill unit. This also gives less likelihood of blocking by surface trash. A feature of some embodiments of the present invention is the provision of a relatively long lead-in portion of the depth skid 36 in order to reduce the possibility of blocking of the depth skid by surface trash The long gentle inclination of the lead-in portion 38 enables the depth skid to deal more easily with surface trash. Furthermore because of the greater force which can be applied to each disc without fear of over penetration, the discs are more easily able to cut through surface trash such as straw rather than burying the straw in the slits. Finally there may be provided a modification (not shown) of the depth skid shown in Figure 4 in which the skid is formed with two ground contact portions positioned one on each side of the disc 16. Preferably in such a case the ground-contact portions of the depth skid are positioned slightly forwardly of the lowest portion of the disc 16, so that any surface trash such as straw is held taut on the ground just before the disc meets the straw, with the result that the disc more easily cuts the straw rather than burying it in the slit. WHAT WE CLAIM IS:-

1. A seed drill comprising a frame for movement over the soil, a rotatable disc for cutting a slit-like furrow in the soil, seed conduit for delivering seed to that part of the furrow adjacent the cutting disc at the time of seed delivery, elongate mounting means pivoted at its leading end to the frame and with the cutting disc mounted at its trailing end thereby to allow substantially vertical movement of the disc relative

to the frame, means for urging the disc downwardly relative to the frame, and a skid fixed relative to the rotation axis of the disc and having a contact portion substantially confined to the vicinity of the cutting disc and adapted to rest on and slide over the soil thereby to limit the depth and pentration of the disc into the soil.

2. A seed drill according to Claim 1 in which the mounting means is adapted to allow pivotal movement of the disc relative to the frame about a pivot point spaced from the disc by a distance substantially greater than the distance of substantially vertical movement allowed by the mounting means.

3. A seed drill according to Claim 1 or Claim 2 in which the seed conduit is coupled to a seed outlet means mounted on the said mounting means adjacent the said disc.

4. A seed drill according to any preceding claim in which the depth limiting element is fixed in normal operation relative to the axis of rotation of the cutting disc and is coupled to the mounting means to move relative to the frame with movement of the cutting disc.

5. A seed drill according to any preceding claim in which the depth limiting element is positioned alongside the cutting disc at a height above the bottom of the cutting disc by an amount equal to the desired depth of cutting of the cutting disc.

6. A. seed drill according to any preceding Claim in which the depth skid comprises a lead-in portion comprising an elongated guide member of greater length than said contact portion of the skid, the elongated guide member leading from the contact portion forwardly and upwardly relative to the direction of movement of the frame.

.

7. A seed drill according to Claim 6 in which the depth skid has its contact portion at the rear of the elongated mounting member and is fastened to the elongated mounting member at the forward upper end of the lead-in portion of the depth skid.

8. A seed drill according to Claim 7 in which the junction of the forward portion of the depth skid with the mounting means is in the region of the pivot of the elongated member on the frame, the contact portion of the depth skid being at the trailing end of the elongated mounting member and therebelow.

9. A seed drill according to any preceding claim in which the depth limiting element is provided with a deflector plate inclined to the horizontal and positioned closely adjacent the cutting disc, the deflector plate being arranged in a position such that in operation seed delivered by the seed con duit strikes the deflector plate and is deflected sideways into the furrow cut by the disc.

10. A seed drill according to Claim 9 in which the said inclined deflector plate is inclined at an angle lying in the range 450 to 800.

11. A seed drill according to Claim 10 in which the deflector plate is inclined to the horizontal at an angle lying in the range 600 to 700.

12. A seed drill according to any of Claims 9 to 11 in which the said deflector plate comprises an upstanding plate mounted on the said contact portion of the depth skid.

13. A seed drill according to any preceding claim in which the cutting disc comprises a dish shaped disc.

14. A seed drill according to Claim 13 in which the depth limiting element is positioned on the convex side of the said dished disc.

15. A seed drill according to Claim 13 or 14 in which the axis of rotation of the cutting disc is inclined to the horizontal with the concave side of the disc facing downwardly.

16. A seed drill according to Claim 15 in which the angle of inclination of the axis to the horizontal is in the range O10 degrees.

17. A seed drill according to Claim 16 in which the angle of inclination of the axis to the horizontal is substantially 40.

18. A seed drill according to any preceding claim in which the axis of rotation of the cutting disc is inclined at an angle to a transverse axis of the frame (as hereinbefore defined).

19. A seed drill according to Claim 18 in which the angle of inclination of the axis of rotation of the cutting disc to the transverse axis of the frame is in the range 3 to 100.

20. A seed drill according to Claim 19 in which the angle of inclination of the axis of rotation of the cutting disc to the transverse axis of the frame is substantially 60.

21. A seed drill according to any preceding claim in which the means for urging the disc downwardly comprises a compression spring.

22. A seed drill according to Claim 21 in which the compression spring acts between the trailing end of the mounting member and the frame.

23. A seed drill according to any preceding claim in which said seed conduit comprises a first conduit, the drill further including a second conduit leading to the slit cut by the cutting disc from a separate hopper adapted to deliver fertiliser to the soil together with the seeds.

24. A seed drill according to any preceding claim in which the frame carries a plurality of said rotatable cutting discs arranged in a transverse array across the line of travel of the frame, each disc having a said mounting means individual thereto and a said seed conduit individual thereto.

25. A seed drill according to any preceding claim in which the frame comprises a flexible conduit leading from a common seed hopper to a seed outlet means individual to the cutting disc and mounted for movement relative to the frame with the cutting disc.

26. A seed drill according to Claim 24 or Claim 25 in which the depth skid is as wide as possible having regard to the positioning of adjacent cutting discs

27. A seed drill according to Claim 26 in which the depth skid is no less than 2" wide taken in a direction generally transverse to the direction of forward travel of the frame.

28. A seed drill substantially as hereinbefore described with reference to the accompanying drawings.