A seed drill or seed planter.

Abstract

A seed drill 1 comprises a frame 2 to be towed behind, or mounted on, a tractor, and having at least one first tool bar 3a with, mounted thereon, a plurality of equally spaced apart first seed dispens

Description

Large modern seed drills or seed planters are normally arranged to be towed by a tractor and normally comprise a frame on which a plurality of dispensers for the seed are arranged. Each dispenser is appropriately placed such that as the seed drill or planter is towed by a tractor, seed is dispensed in equally spaced rows. Each dispenser may for example comprise a coulter, which may have a single disk offset from the direction of travel to open a furrow, or a pair of disks forming a V-shape and arranged to open a furrow, into which seed is placed before a closing wheel subsequently closes the furrow. However, many other types of dispenser exist and a dispenser may simply comprise a tine opening a furrow into which seed is dispensed, or the seed may be dispensed directly onto the ground from a dispensing tube, for example. When sowing certain types of crops, such as wheat or barley the seed is normally continuously blown into the open furrow as the seed drill moves forward, but with other crops, such as sugar beet, the seed needs to be regularly spaced and seed singulation meters may be employed which cause a seed to be planted in a line at predetermined distances from each other. Irrespective of the type of dispensers used on a seed drill, or seed planter, seed to be dispensed is normally blown or delivered to each dispenser via an associated connecting tube. Each dispenser is then normally manually mounted to a frame of the seed drill or planter, in a fixed position, to provide an appropriate spacing between adjacent dispensers in the transverse direction relative to the direction of travel of the seed drill, to provide a corresponding spacing between the rows of seed planted. In its simplest form, a seed drill may comprise a single linear toolbar extending in the transverse direction, with every dispenser mounted on the toolbar at a desired location and with the spacing between each adjacent pair of dispensers matching the desired spacing between adjacent rows of the crop to be planted. However, this is often impracticable due to the relatively close spacing that may be required between rows of a crop and the size of the dispensers, particularly where the dispensers are coulters. Thus, it is common for seed drills or planters to employ a frame having multiple transverse toolbars, typically two or four, with adjacent dispensers in the transverse direction being placed on different toolbars. As an example of the above, a frame may comprise four parallel toolbars each extending transversely to the direction of travel and placed one behind the other in the direction of travel. Dispensers will then typically be mounted transversely across the frame, with the first dispenser (if for example working from left to right) mounted to the first (front) toolbar, the second dispenser mounted on the second toolbar spaced in a transverse direction (transverse to the direction of travel of the seed drill) by a predetermined spacing equal to the desired spacing between the rows of crops being planted, with the third dispenser mounted on the third toolbar separated in the transverse direction from the second dispenser by the same predetermined spacing, with a fourth dispenser mounted on the fourth (rear) toolbar, again separated in the transverse direction by the same predetermined spacing from the third dispenser. The fifth dispenser will then again be mounted on the first (front) toolbar, separated in the transverse direction from the fourth dispenser by the same predetermined distance, with this pattern of dispensers being repeated across the frame. The mounting of dispensers on two or more toolbars permits dispensers to be positioned more closely together in the transverse direction, so that rows of seed may be closely spaced together. Such an arrangement also greatly eases the flow of any residual crop and soil through the seed drill or planter, particularly where coulters or tines are employed to cut furrows for the seed to be dispensed into. Irrespective of the layout of the dispensers on the frame of a seed drill, or planter, each dispenser is normally arranged to be manually fixed by being clamped or bolted to the frame in a desired position, so that the dispenser can initially be set up for the type of crop that is to be sown, so that a crop sown by the planter will have an appropriate spacing between the rows of the crop. However, if it is desired to use the same seed drill or seed planter to plant crops with a different spacing, then it is normally necessary to manually reposition each dispenser on the frame, which is considerably time consuming. It is the object of the present invention to provide an improved seed drill or planter. According to the present invention, there is provided a seed drill or seed planter for drilling or planting seed, the seed drill or seed planter being arranged, in use, to be moved in a direction of intended travel across an area to be seeded, the seed drill or seed planter comprising: a frame arranged to be towed behind, or mounted behind, a tractor; at least one first tool bar; and a plurality of first dispensers mounted on the at least one first tool bar, equally spaced apart on the at least one first tool bar in a transverse direction, transverse to the direction of intended travel, wherein the seed drill or seed planter comprises at least one actuator arranged to move the at least one first tool bar in the transverse direction relative to the frame and to collectively displace each of the first dispensers in the transverse direction relative to the frame and wherein each of the first dispensers is arranged to dispense an agricultural product in a line which follows the path of the respective first dispenser across the area to be seeded. A seed drill in accordance with the present invention provides a plurality of first dispensers mounted on the at least one first toolbar such that the plurality of first dispensers may be collectively moved in the transverse direction relative to the frame of the seed drill. One significant advantage of this is that it may permit the seed drill or seed planter to be used to initially sow a first crop and then, after that first crop has begun to grow, to under sow a second crop between the rows of the first crop. This may be achieved by sowing the first crop and then, before sowing the second crop, collectively offsetting the dispensers relative to the frame, so that when a tractor towing the seed drill, on the subsequent pass, follows the previous tramlines (straight parallel tracks left in the ground by an agricultural machine), the same dispensers will then dispense seed between the previously planted rows. This can be used to establish cover crops or to seed a legume or other beneficial plant to improve the soil and aid the crop currently growing. Alternatively, those same dispensers could be used to dispense a fertiliser between the rows of previously planted crop. For the avoidance any doubt, as used in the present specification, a reference to being spaced apart, “in the transverse direction” means that the spacing in the transverse direction only is to be taken into consideration. For example, the seed drill may comprise a set of first toolbars placed one behind the other in the direction of travel, with a dispenser placed on each one of these toolbars. In such an arrangement, the transverse spacing (or spacing in the transverse direction) is the separation of two dispensers in the transverse direction only, irrespective of any longitudinal separation in the direction of intended travel of the seed drill or seed planter. Preferably, the seed drill or seed planter further comprises at least one second tool bar and a plurality of second dispensers mounted on the at least one second tool bar, equally spaced apart on the at least one second tool bar in the transverse direction, wherein each of the second dispensers is arranged to dispense an agricultural product in a line which follows the path of the respective second dispenser across the area to be seeded, wherein the second dispensers may be interleaved in the transverse direction with the first dispensers, wherein the plurality of first dispensers are collectively moveable in the transverse direction relative to the plurality of second dispensers such that the spacing, in the transverse direction, between each adjacent pair of first and second dispensers may be varied, and wherein at least one of the pluralities of dispensers is arranged to dispense seed. An arrangement as described above permits the second dispensers to be interleaved in the transverse direction with the first dispensers and permits the spacing between transversely adjacent pairs of first and second dispensers to be collectively varied. Thus, for example, if the plurality of first dispensers are all transversely spaced 50 centimetres apart from each other and the plurality of second dispensers are each transversely spaced 50 centimetres apart from each other, with the second dispensers offset from the first dispensers by 25 centimetres, then this would permit the seed drill to be used to plant wheat, for example, with a 25 centimetre spacing, by using all of the first and second dispensers to sow the wheat. However, if for example organic wheat is to be grown, then the spacing between adjacent pairs of first and second dispensers could be adjusted collectively for the whole seed drill, so that adjacent pairs of first and second dispensers are only 15 centimetres apart. This would result in a crop being sown where the spacing between adjacent rows alternates between 15 and 35 centimetres. This may be desirable when sowing organic wheat, for this retains the overall density of crop while the 15 centimetre spacing between a pair of rows acts to crowd out weeds, with the 35 centimetre spacing between an adjacent pair of rows permits inter-row hoeing to be performed, to provide weed control for the crop. As another example, when planting rape, a 50 centimetre spacing between rows may be desirable. This may be attained by using only the first dispensers of the above arrangement, with the second dispensers, which may be in the form of coulters, raised out of work. However, with the present invention the second dispensers could alternatively be placed back into work with the transverse spacing between adjacent pairs of the first and second dispensers collectively adjusted, so that the second dispensers are each closely adjacent a respective first dispenser, with the second dispensers then being used to dispenser fertiliser in close proximity, but separated from the rape, planted by the first dispensers. As yet a further example, if maize is to be grown, then maize normally dictates a 75 centimetre spacing between rows. The seed drill could thus be set up to have the first dispensers transversely spaced apart from each other by 37.5 centimetres and fed seed via singulation meters (necessary to provide a uniform spacing between the maize seeds) with every other one of the first dispensers placed out of work. This would provide the desired 75 centimetre spacing between rows of seed. The second dispensers could then also be spaced apart from each other also by 18.75 centimetres, but these could be supplied with fertiliser, with every other second dispenser placed out of work and with the second dispensers offset from the first dispensers by 5 centimetres. This would result in a seed drill or planter which would plant rows of maize with a 75 centimetre spacing, but with fertiliser placed 5 centimetres from each row of seed. The same seed drill, configured as above, could then be used to plant wheat, by placing every dispenser into work, switching out the singulation meters, collectively moving the first dispensers relative to the second dispensers so that they are offset from each other by 18.75 centimetres and supplying wheat seed to all of the dispensers. This would then result in rows of wheat being sown 18.75 centimetres apart. This enables a single seed drill to be used for sowing both types of crop, without having to manually reposition each of the dispensers on the frame. Preferably, the separation in the transverse direction between each adjacent pair of first dispensers is substantially equal to the separation in the transverse direction between each adjacent pair of second dispensers. This enables the first and second dispensers to be interleaved and the advantages explained above to be achieved. Preferably, the at least one second tool bar is arranged to be moved in the transverse direction relative to the frame and to collectively displace each of the second dispensers in the transverse direction relative to the frame. This enables a greater range of displacement between any one first dispenser and any one second dispenser for a limited range of transverse travel of the at least one first toolbar and the at least one second toolbar. More preferably, the seed drill or seed planter comprises one or more actuators arranged to transversely displace both of the at least one first toolbar and the at least one second toolbar in opposite transverse directions relative to the frame. This permits the distribution of the combined first and second dispensers to remain centred in the transverse direction, relative to a point on the frame and thus permits the dispensers to remain centred behind a tractor, avoiding any tendency for the seed drill to crab behind the tractor, which crabbing would result in an incorrect spacing between the rows of crop. It is preferably if the seed drill comprises an equal number of first and second dispensers, wherein, with the exception of an outermost first dispenser, the first dispensers are interleaved in the transverse direction between adjacent ones of the second dispensers, and wherein the at least one first toolbar is arranged to be displaced in the transverse direction, relative to the at least one second toolbar, by a distance substantially equal to the spacing between adjacent, in the transverse direction, pairs of first dispensers. The advantage of the immediately above arrangement is that if the first and second dispensers are dispensing different agricultural products, for example the first dispensers are dispensing seed and the second dispensers are dispensing fertilizer, then on turning on a headland the first dispensers may collectively be moved transversely relative to the second dispensers so that the endmost dispenser on each side of the frame will switch from a first dispenser to a second dispenser and from a second dispenser to a first dispenser, so that the products will continue to be placed in alternate rows across the area to being seeded. Preferably, the seed drill comprises a first hopper for containing a first agricultural product; a second hopper for containing a second agricultural product; a plurality of first connecting tubes each connected at one end to, or forming, a first dispenser; and a plurality of second connecting tubes each connected at one end to, or forming, a second dispenser, wherein each of the first connecting tubes is connected to, or is arranged to be connected to, the first hopper, and each of the second connecting tubes is connected to, or is arranged to be connected to the second hopper. The above arrangement permits two type of agricultural product, for example seed and fertiliser, to be dispensed to the first and second dispensers respectively and preferably the plurality of first connecting tubes, or the plurality of second connecting tubes are arranged to be collectively connected to either of the first or second hoppers, permitting the seed drill or seed planter to be more quickly reconfigured. The seed drill or seed planter may comprise a global positioning system (GPS) receiver arranged to be able to determine, directly or indirectly, the position of one of the first dispensers, wherein the transverse position of that dispenser is controlled in dependence on the output of the GPS receiver. This may be used to cause at least one dispenser to follow a GPS line and this may thus be used to keep all of the dispensers correctly positioned relative to that GPS line. This will not only ensure “fine tuning” of the position of the sown or planted seed, but this will also detect crabbing of the seed drill or seed planter behind the tractor, for example when it traverses across a slope, where the seed drill or seed planter may tend to drift down the slope. The detection of this drift may then be used to adjust the position of the dispensers on the frame so that they remain aligned relative to the tractor and centred on the tramlines. The detection of sideways drift, or crabbing, may also be used to adjust the spacing between the first and second dispensers, where this is necessary to maintain the spacing between adjacent rows of agricultural product dispensed by transversely adjacent first and second dispensers. This may become necessary where a first dispenser is longitudinally displaced on the frame from an adjacent second dispenser, where for example they may be located on respective first and second toolbars, with one toolbar possibly positioned two metres behind the other. Here, any crabbing or skewing of the seed planter behind the tractor will cause the spacing between adjacent rows of seed dispensed by the dispensers to vary and thus detection of the crabbing may be used to correct this. The seed drill or seed planter may further comprise a camera arranged to permit the position of a row of growing crop to be determined relative to the transverse position of a first dispenser, wherein the transverse position of the first dispensers is controlled in dependence on a signal from the camera. This enables at least the position of the first dispensers to be controlled such that they may dispense seed between rows of the growing crop. Alternatively, or additionally, the seed drill or seed planter may further comprise a plurality of hoes arranged to be attached to respective ones of the plurality of first dispensers, whereby if a camera is also employed this may be used to control the position of the plurality of first dispensers and thus the plurality of hoes, such that the seed drill may be used to not only plant seed but also to subsequently hoe between the rows of seed planted by that seed drill. Where the seed drill or seed planter comprises a GPS receiver or camera, used to control the transverse position of at least one dispenser, it is advantageous if the seed drill or seed planter further comprises a sensor arranged to detect the transverse position of that dispenser relative to the frame. This may be used to provide feedback indicating the remaining travel range available of the dispenser relative to the frame, which in turn could, if necessary, be used to signal to the tractor to transversely reposition itself, to maintain an appropriate range of transverse travel of that dispenser relative to the frame. The sensor could take any appropriate form, for example a linear encoder detecting the transverse position of the at least one toolbar, on which that dispenser is mounted, relative to the frame, or a rotary encoder for detecting the rotation of a motor or leadscrew of an actuator controlling the transverse position of that at least one toolbar relative to the frame. Depending on the application, the at least one actuator may comprise at least one hydraulic ram or a leadscrew. In either case this may use active control, using feedback from a position sensor or GPS receiver, to control the position of either the at least one first tool bar and / or the at least one second toolbar. Alternatively, the actuator may use passive control where the actuators expand and contract to preset positions determined by at least one of the limit of the range of the actuator, one or more stops or, in the case of hydraulic rams, the use of selective valves. Advantageously, each of the dispensers is arranged to be manually fixed at one of a plurality of positions on a respective at least one toolbar, to permit the spacing in the transverse direction between adjacent ones of the dispensers to be manually set. This permits the spacing of the dispensers to be initially set either at a factory, a distributor or on the farm, to a spacing suitable for the expected requirements of the farm. Although this is a very time consuming process and it would not be desirable to perform this on a regular basis, it may permit a standard seed drill or planter to be manufactured and then subsequently tailored to the requirements of a specific farm, or permit the seed drill or planter to be reconfigured, for example, in response to the type of crops grown on a farm being changed or as a result of the seed drill or planter being sold. Advantageously, each dispenser can be individually placed in or out of work. This is a common design feature of seed drills and permits dispensers in line with the tramlines to be deactivated to avoid damage from running through compacted ground and to avoid sowing unnecessary rows of seed. However, with a seed drill or seed planter in accordance with the present invention, this also enables greater flexibility when configuring the seed drill or seed planter, as described above. The present invention will now be described, by way of example only, with reference to the following drawings, in which like numerals are used throughout to indicate like parts and of which: Figure 1 is a schematic diagram of a tractor and a seed drill or seed planter in accordance with the present invention; Figures 2a and 2b are schematic diagrams of a mechanism for shifting toolbars of the seed drill or seed planter of Figure 1; Figures 3a to 3d are schematic diagrams of the seed drill or seed planter of Figure 1, illustrating how the spacing between lines of dispensed product can be varied; and Figures 4a to 4c are schematic diagrams of the seed drill or seed drill of Figure 1, illustrating how the rows can be moved to correct for the effects of crabbing on the spacing between the lines of dispensed product. References to a seed drill below are to be interpreted to also encompass a seed planter. Figure 1 shows a seed drill, illustrated generally as 1, being pulled by a tractor 9 in a direction of intended travel 11, across an area to be seeded, the tractor following or creating tramlines 8. As discussed below, in the described embodiment the seed drill 1 cuts a series of furrows into the soil and dispenses seed into those furrows. However, the seed could be placed directly on the surface of the soil and the seed drill may be used to dispense additional agricultural products, such as fertiliser. The seed drill 11 comprises a frame 2, a drawbar 10, a first hopper 6a and a second hopper 6b mounted on the frame 2, both of which may hold seed or fertiliser. The seed drill 1 also comprises a first toolbar 3a, to which are mounted a plurality of first dispensers 5a, and a second toolbar 3b, to which are mounted a plurality of second dispensers 5b. In the illustrated embodiment all the dispensers 5a, 5b are configured to dispense the seed or fertiliser stored in the hoppers 6a, 6b. Each first dispenser 5a is connected to the first hopper 6a via a first connecting tube 7a, through which it receives the seed or fertiliser stored in the first hopper 6a. Similarly, each second dispenser 5b is connected to the second hopper 6b via a respective second connecting tube 7b. In an alternative arrangement, each connecting tube 7a, 7b may form a dispenser, rather than connecting to a separate dispenser 5a, 5b. Also, in an alternative arrangement, there may only be one hopper to which both the first dispensers 5a and second dispensers 5b are connected. In a further alternative arrangement either the first connecting tubes 7a, the second collecting tubes 7b, or both, may be arranged to be collectively connected to one of at least two hoppers. Each dispenser 5a, 5b may include a coulter 12 which precedes the rest of the dispenser as the seed drill 5a, 5b moves in the direction of intended travel. The coulter may for example be in the form of a single angled disc or a V - shaped pair of discs. The coulter may be in an active state, where it cuts a furrow, or an inactive state where it is raised clear of the ground. As the seed drill 1 moves in the direction of intended travel, it produces a series of furrows, equal in number to the number of dispensers 5a, 5b with active coulters 12, each furrow following the path of the dispenser 5a, 5b and associated coulter by which it was cut. The furrows 15 are depicted in the simplified schematic diagrams of Figures 3a to 5c, discussed in more detail below. Each dispenser 5a, 5b may dispense either seed or fertiliser. Those dispensers 5 dispensing seed will typically have active coulters 12 as seeds are normally dispensed into a furrow, whereas those dispensing fertiliser will only have active coulters 12 where the fertiliser is to be placed below the soil surface, instead of on top of the soil surface. Each dispenser 5a, 5b may be in an active or inactive state, where seed or fertiliser are only dispensed in the active state. This is discussed in more detail below, with respect to Figures 3a and 3b. Each dispenser 5a, 5b may be fed seed by an associated singulation meter which can be activated or deactivated. When activated, the singulation meters dispenses seeds one at a time at regular intervals. When the singulation meter is deactivated, the dispenser blows out the seed (or fertiliser) as an almost continuous stream. Wheat and barley, for example, are normally dispensed without a singulation meter, the singulation meter being used for seeds such as maize, sugar beet, sunflower and soya, which need a more regular spacing in order to maximise yield. In the illustrated and schematic embodiment of Figure 1, a number of first dispensers 5a are fixed to a first toolbar 3a with a uniform first spacing between them, with an equal number of second dispensers 5b fixed to a second toolbar 3b with a uniform second spacing between them, equal to the first spacing. Although in the schematic diagram of Figure 1, for simplicity, a single first toolbar 3a and a single second toolbar 3b are illustrated, in order to permit the first dispensers 5a and / or the second dispensers 5b to be positioned sufficiently closely together in the transverse direction, the seed drill may comprise multiple transverse first toolbars 3a with adjacent, in the transverse direction, first dispensers 5a being positioned on different first toolbars, and multiple transverse second toolbars 3b with adjacent, in the transverse direction, second dispensers 5b being positioned on different second toolbars, in the manner described in the introductory portion of this specification. The dispensers 5a, 5b will typically be individually and manually fixed to their respective toolbars 3a, 3b, on an initial set up of the seed drill 1, by bolting or clamping them to the toolbars 3a, 3b. The positions will be selected such that the spacings between the first dispensers 5a and between the second dispensers 5b, are appropriate for the crops expected to be sown using the seed drill 1. The first toolbars and second toolbars 3a and 3b are both supported by portions of the frame 2 and are arranged to be displaced transversely relative to the frame 2 by a mechanical control mechanism employing an actuator and indicated schematically as 4 in Figure 1. Where, in practice, the first dispensers 5a may be mounted on multiple first toolbars 3a (only one shown) and the second dispensers 5b may be mounted on a plurality of second toolbars 3b (only one shown), each of the plurality of first toolbars 3a will be arranged to move transversely together as a first unit and each of the plurality of second toolbars 3b will be arranged to move transversely together as a second unit, separate to the first unit. The toolbars 3a and 3b will normally be positioned so that the dispensers 5a, 5b, that are in work, are collectively centred on the drawbar 10, to avoid any tendency for the seed drill to crab (slew) to one side behind the tractor 9. The position of the first and second toolbars 3a and 3b may be controlled passively, with one or more actuators of the control mechanism 4 being arranged to expand and / or contract to preset positions determined by the limit of the range of the actuator, by one or more stops which may be selectively inserted or, in the case of hydraulic rams, by the selective operation of associated valves. As an alternative to the above, the one or more actuators of the control mechanism 4 may be actively controlled to actively control the first and second toolbars 3a and 3b, using feedback from any appropriate means, such as, for example, GPS receivers 17a and 17b which give the true position of the respective toolbars 3a, 3b, permitting one dispenser 5a, 5b on each toolbar 3a, 3b to follow a respective GPS line and thus keep all of the dispensers 5a, 5b on the toolbars 3a, 3b correctly positioned relative to the respective GPS lines. This will not only ensure “fine tuning” of the position of the sown or planted seed under normal conditions, but this may also correct for any transverse offset that may otherwise occur due to crabbing of the seed drill or seed planter 1 behind the tractor 9. As another example, active control may use the output of cameras 18a, 18b to keep the position of a respective toolbars 3a or 3b appropriately aligned relative to rows of an already established crop. As a third example, active control may use sensors 19a, 19b to provide the position of the respective toolbars 3a, 3b relative to the frame 2, in order to keep the dispensers at the correct transverse positions relative to the frame 2. Typically, the actuator or actuators may comprise hydraulic rams or motors driving associated leadscrews, but other types of actuators may also be used Referring now to Figures 2a and 2b these illustrate one possible implementation of the mechanical mechanism 4 of Figure 1. However, in practice, the frame 2 and toolbars 3a and 3b would be a lot wider in the transverse direction than the portions shown in Figures 2a and 2b and may typically be up to 12 metres in width, with the frame 2 and toolbars 3a and 3b being formed as hinged sections, to permit folding for transportation, as is common practice in the field of seed drills. As shown in Figure 2a, each toolbar 3a, 3b is connected to a central portion 16 of the frame by respective swing arms 13a or 13b and a respective actuator 14a or 14b. Each swing arm 13a, 13b is pivotably connected to a toolbar 3a or 3b at one end and to the central portion 16 of the frame 2 at the other end. The actuators 13a, 13b may be hydraulic rams or electric actuators. As can be seen from a comparison of Figures 2a and 2b, each of the actuators 14a and 14b are configured to move a respective toolbars 13a or 13b between different positions, such that the positions of the first dispensers 5a and second dispensers 5b can be adjusted in the transverse direction relative to each other, by the actuators 14a and 14b moving the toolbars 3a and 3b in opposed transverse directions. This will thus adjust the positions of the furrows and the lines of dispensed seed or fertiliser relative to each other and to the tramlines 8, followed, or left by, the tractor 9 of Figure 1. Although an arrangement has been shown in Figures 2a and 2b which uses swing arms 13a and 13b, an arrangement could be employed where the toolbars 3a and 3b are arranged to slide transversely on transverse guide bars attached to or forming part of the frame 2, with one or more linear actuator again controlling the position of the toolbars 3a and 3b relative to the frame. Turning now to Figures 3a to 4c, these are provided to illustrate how the seed drill of Figures 1 to 2b may be used to sow different crops with different row spacings and how the seed drill may be used to maintain a desired spacing during crabbing. For simplicity, each figure shows only representations of the tractor 9, the direction of intended travel 11, the first and second toolbars 13a and 13b, the relative positions of illustrative first dispensers 5a and illustrative second dispensers 5b and the positions of lines 15a, 15b of dispensed product (seed or fertiliser). Referring first to Figure 3a, here the first dispensers 5a on the first toolbar 3a are interleaved with and equally spaced from, in the transverse direction, the second dispensers 5b on the second toolbar 3b, such that the lines 15a of product dispensed by the first dispensers 5a are uniformly spaced with a spacing do from the lines 15b of second product dispensed by the second dispensers 5b. If, for example, the first dispensers 5a are spaced 50 centimetres apart from each other on the first toolbar 3a and the second dispensers are spaced 50 centimetres apart from each other on the second toolbar 3b then the seed drill could be configured to sow wheat through both the first and second dispensers 5a, 5b, with a spacing of 25 centimetres (do) between the rows of sown crop. In a first alternative configuration to the above, the first dispensers 5a could use singulation meters to dispense lines 15a of uniformly spaced maise seeds, with fertiliser dispensed through the second dispensers 15b, resulting with a maise crop with a 50 centimetre spacing between adjacent rows of crop and with fertiliser dispensed between the rows. A crop such as maise though would ideally have a spacing between the rows of 75 centimetres (3do). Figure 3b illustrates how this may be achieved by dispensing maise seeds, using singulation meters, to both the first and second dispensers 5a and 5b, with selected ones of those dispensers placed out of use, as represented by those marked with an “X”. The same seed drill 1, with the same initial set up could also be used to sow organic wheat, with the toolbars 3a and 3b positioned as shown in Figure 3c, such that the first dispensers 5a and the second dispensers 5b are collectively moved to the positions shown in Figure 3b, where the dispensers 5a and 5b remain collectively centred on the drawbar 10, but with each second dispensers 5b positioned 15 centimetres from one adjacent first dispenser 5b and 35 centimetres from the other. Here all of the first dispensers 5a and all of the second dispensers 5b are set to dispense lines of seed 15a, 15b resulting in a crop being sown where the spacing between adjacent rows alternates between 15 and 35 centimetres. With the above arrangement, the overall density of crop would be the same as for a crop sown with a normal 25 centimetre spacing between the rows, but here the 15 centimetre spacing between a pair of rows acts to crowd out weeds, with the 35 centimetre spacing between an adjacent pair of rows permitting inter-row hoeing to be performed, to provide weed control for the crop. As another example, when planting rape, a 50 centimetre spacing between rows may be desirable. This may be attained by positioning the first and second toolbars to the positions shown in Figure 3d and using only the first dispensers 5a to dispense lines of seed 15a, while dispensing fertiliser through the second dispensers 5b in lines 15b closely adjacent to respective lines 15a of seed. This configuration is particularly advantageous where fertiliser needs to be dispensed close to a furrow, to stimulate growth of the seed, but where it cannot be placed directly on the seed as it would burn the seed. Depending on the crops to be grown on a farm where the seed drill 1 is to be used, instead of a 25 centimetre spacing between adjacent first dispensers 5a and a 25 centimetre spacing between adjacent second dispensers 5b, these could both be manually set for each dispenser individually, during an initial set up, to some other spacing, for example 37.5 centimetres. Then, with reference again to Figures 3a to 3b, but assuming this new 37.5 centimetre spacing, if maize is to be grown, which ideally dictates a 75 centimetre spacing between rows, the toolbars 3a and 3b could be moved to the positions shown in Figure 3b. Those dispensers indicated by a “X” could then be placed out of work and maise seeds dispensed via seed meters through the remaining dispensers 5a and 5b. As will be appreciated from Figure 3b, with only every third dispenser of the combiner dispensers 5a and 5b in work, the lines of seed 15a, 15b dispensed would then have a spacing of 75 centimetres (3do). The same seed drill, configured as above, could then be used to plant wheat, by placing every dispenser into work, switching out the singulation meters, positioning the toolbars 3a and 3b to the positions shown in Figure 3a and thus collectively moving the first dispensers 5a relative to the second dispensers 5b so that they are offset from each other by 18.75 centimetres and supplying wheat seed to all of the dispensers 5a and 5b. This would then result in rows of wheat being sown 18.75 centimetres apart. This enables one seed drill 1 to be used for sowing both types of crop without having to manually reposition each of the dispensers 5a, 5b on a frame. A further significant advantage of the seed drill 1, described above, is that where a first agricultural product, such as seed, is being dispensed by the first dispensers 5a and a different agricultural product, such as fertilizer, is being dispensed by the second dispensers 5b, then on turning on a headland the first dispensers 5a may collectively be moved transversely relative to the second dispensers 5b so that the endmost dispenser on each side of the frame will switch, so that the products will continue to be placed in alternate rows across the area to being seeded. Another advantage of having the moveable toolbars 3a, 3b is illustrated with reference to Figures 4a to 4c. Figure 4a shows the two toolbars 3a, 3b in the same configuration as shown in Figure 1. However, here the entire seed drill 1 is skewed at an angle (crabbing) behind the tractor 9 and relative to the direction of intended travel 11. This skewing has been greatly exaggerated in the figures, but from Figure 4a it will be realised that because of the front to back spacing between the toolbars 3a and 3b, which may typically be 2.2 metres, the crabbing results in non-uniform spacings dci and dC2 between the furrows / lines of dispensed seed. Additionally, the dispensers are no longer symmetrically centred on the tramlines, so that any out of work dispensers, normally aligned with the tramlines will be leaving unseeded strips, while in work dispensers will now be in work in the tramlines, both wasting seed by sowing in the tramlines and risking a mechanical failure due to working in the compacted soil. Figure 4b shows how the toolbar 3b can be moved to the right, as shown, so that uniform spacing dcocan be recovered between the lines of dispensed seed, although dco will be less than do of Figure 1, but this difference will be minimal. Here also, the dispensers will still not be correctly aligned with the tramlines 8 left by the tractor 9. This can also be corrected for, as shown in Figure 4c where the toolbars 3a and 3b are both offset to the same side (in this example, to the right on the frame 2), to maintain the dispensers 5a, 5b aligned relative to the tramlines 8 even during crabbing of the seed drill 1. Any crabbing may be detected visually by the tractor operator and the position of the toolbars 3a and 3b manually adjusted, but more preferably this will be performed automatically by GPS receivers 17a and 17b mounted on the seed drill 1. These are shown in Figures 4a to 4c mounted on the toolbars 3a and 3b and are used to maintain the receivers on respective GPS lines, thus maintaining the dispensers 5a, 5b in the correct transverse positions even during crabbing, maintaining a correct positioning and thus uniform spacing between the lines of dispensed seed, or seed and fertiliser, 15a, 15b. The invention has been described above with reference to a seed drill 1 with two toolbars 3a and 3b, both of which may be moved. However, the invention is not limited to arrangement having two movable toolbars 3a and 3b and it will be appreciated that many of the same advantages may be obtained if, for example, the first dispensers 5a are mounted on a movable toolbar 3a with the dispensers 5b fixed relative to the frame, although with such an arrangement it would not be possible to maintain the combined dispensers centred behind a tractor, but on a wide seed drill 1 with a relatively small spacing between adjacent dispensers it may be acceptable to just to have one moving toolbar. In addition to the above, the seed drill 1 may comprise only a plurality of first dispensers 5a all fixed to a first toolbar 3a which first toolbar 3a is arranged to move relative to the frame 2, for even a single movable toolbar 3a with a single array of dispensers 5a provides advantages. For example, a tractor 9 following or 5 making a set of tramlines 8 may plant a seed on a first pass and then, once the crop is established, make a second pass with the same dispensers, but with the toolbar 3a offset, such that on the second pass the same dispensers 5a undersow seed between the already established crop. Alternatively, hoes (not shown) may be fitted to the front of the dispensers 5a and the seed drill 1 may then be used to 10 hoe between the rows of crop sown by the same drill. Here a camera 18a, as shown in Figure 1, may be mounted on the toolbar 3a to permit automated adjustment of the position of the toolbar 3a to keep the hoes aligned with the gaps between the rows of the previously sown crop. 15 Although the invention has been described above, by way of example only, with reference to the accompanying drawings, it will be appreciated that many variations and modifications may be possible which fall within the scope of the following claims.

Claims

1. A seed drill or seed planter for drilling or planting seeds, the seed drill or seed planter being arranged, in use, to be moved in a direction of intended travel across an area to be seeded, the seed drill or seed planter comprising: a frame arranged to be towed behind, or mounted behind, a tractor; at least one first tool bar; and a plurality of first dispensers mounted on the at least one first tool bar, equally spaced apart on the at least one first tool bar in a transverse direction, transverse to the direction of intended travel, wherein the seed drill or seed planter comprises at least one actuator arranged to move the at least one first tool bar in the transverse direction relative to the frame and to collectively displace each of the first dispensers in the transverse direction relative to the frame and wherein each of the first dispensers is arranged to dispense an agricultural product in a line which follows the path of the respective first dispenser across the area to be seeded.

2. A seed drill or seed planter as claimed in Claim 1, further comprising at least one second tool bar and a plurality of second dispensers mounted on the at least one second tool bar, equally spaced apart on the at least one second tool bar in the transverse direction, wherein each of the second dispensers is arranged to dispense an agricultural product in a line which follows the path of the respective second dispenser across the area to be seeded, wherein the second dispensers may be interleaved in the transverse direction with the first dispensers, wherein the plurality of first dispensers are collectively moveable in the transverse direction relative to the plurality of second dispensers, such that the spacing, in the transverse direction, between each adjacent pair of first and second dispensers, may be varied and wherein at least one of the pluralities of dispensers is arranged to dispense seed.

3. A seed drill or seed planter as claimed in Claim 2, wherein the separation in the transverse direction between each adjacent pair of first dispensers is substantially equal to the separation in the transverse direction between each adjacent pair of second dispensers.

4. A seed drill or seed planter as claimed in Claim 2 or 3 wherein the at least one second tool bar is arranged to be moved in the transverse direction relative to the frame and to collectively displace each of the second dispensers in the transverse direction relative to the frame.

5. A seed drill or seed planter as claimed in Claim 2, 3 or 4 comprising one or more actuators arranged to transversely displace both of the at least one first toolbar and the at least one second toolbar in opposite transverse directions relative to the frame, such that the distribution of the combined first and second dispensers may remain centred, in the transverse direction, relative to a point on the frame.

6. A seed drill or seed planter as claimed in any one of Claims 2 to 5 comprising an equal number of first and second dispensers, wherein, with the exception of an outermost first dispenser, the first dispensers are interleaved in the transverse direction between adjacent ones of the second dispensers, and wherein the at least one first toolbar is arranged to be displaced in the transverse direction, relative to the at least one second toolbar, by a distance substantially equal to the spacing between adjacent, in the transverse direction, pairs of first dispensers.

7. A seed drill or seed planter as claimed in any one of Claims 2 to 6 wherein the plurality of first dispensers and / or the plurality of second dispensers are moveable collectively, to positions where the first and second dispensers are positioned such that in use agricultural product or products dispensed by both the first and second dispensers is dispensed in equally spaced lines.

8. A seed drill or seed planter as claimed in any one of Claims 2 to 7 wherein each second dispenser is positioned in the transverse direction between an adjacent pair of first dispensers and wherein the plurality of first dispensers and / or the plurality of second dispensers, are collectively moveable to positions where the second dispensers are each positioned such that, in use, agricultural product fromeach second dispenser is dispensed more closely to an agricultural product dispensed by a respective first dispenser of each respective adjacent pair of first dispensers than it is to an agricultural product dispensed by the other of the first dispensers of each adjacent pair of first dispensers.

9. A seed drill or seed planter as claimed in any one of Claims 2 to 8 comprising: a first hopper for containing a first agricultural product; a second hopper for containing a second agricultural product; a plurality of first connecting tubes each connected at one end to, or forming, a first dispenser; and a plurality of second connecting tubes each connected at one end to, or forming, a second dispenser, wherein each of the first connecting tubes is connected to, or is arranged to be connected to, the first hopper, and each of the second connecting tubes is connected to, or is arranged to be connected to the second hopper.

10. A seed drill or seed planter as claimed in Claim 9, wherein the plurality of first connecting tubes, or the plurality of second connecting tubes are arranged to be collectively connected to either of the first or second hoppers.

11. A seed drill or seed planter as claimed in Claim 9 or 10 wherein the plurality of first dispensers are arranged to dispense seed and the plurality of second dispensers are arranged to dispense fertiliser.

12. A seed drill or seed planter as claimed in any one of Claims 9 or 10 wherein the plurality of first dispensers are arranged to continuously drill seed and the plurality of second dispensers comprise singulation meters and are arranged to individually plant seeds.

13. A seed drill or seed planter as claimed in any preceding claim wherein the first dispensers are configured to continuously seed.

14. A seed drill or seed planter as claimed in any one of Claim 1 to 11 wherein the first dispensers each comprise a singulation meter configured to permit precision planting of seed.

15. A seed drill or seed planter as claimed in any preceding claim further comprising a global positioning system (GPS) receiver arranged to be able to determine, directly or indirectly, the position of one of first dispensers wherein the transverse position of that dispenser is controlled in dependence on the output of the GPS receiver.

16. A seed drill or seed planter as claimed in any preceding claim further comprising a camera arranged to permit the position of a row of growing crop to be determined relative to the transverse position of a dispenser, wherein the transverse position of the first dispensers is controlled in dependence on a signal from the camera.

17. A seed drill or seed planter as claimed in Claim 15 or 16 further comprising a sensor arranged to detect the transverse position of a dispenser relative to the frame.

18. A seed drill as claimed in any preceding claim further comprising a plurality of hoes arranged to be attached to respective ones of the plurality of first dispensers.

19. A seed drill or a seed planter as claimed in any preceding claim wherein the at least one actuator comprises at least one hydraulic ram or a leadscrew.

20. A seed drill or seed planter as claimed in any preceding claim wherein each of the dispensers is arranged to be manually fixed at one of a plurality of positions on a respective at least one toolbar, to permit the spacing in the transverse direction between adjacent ones of the dispensers to be manually set.

21. A seed drill or seed planter as claimed in any preceding claim wherein each dispenser can be individually placed in or out of work.

22. A seed drill or seed planter as claimed in any preceding claim, wherein each 5 of the first dispensers, is a disc coulter.

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