GB2176982A - Rotary cultivator - Google Patents

Abstract

An agricultural machine comprises a rotatable transverse assembly and a plurality of agricultural tools connected to the support assembly to lift and project soil forwardly thereby to work the soil in a continuous path parallel to the direction of movement of the machine. The machine is multi-functional in the sense that a number of different agricultural tools can be fitted to the machine. One function is to prepare a series of continuous parallel rows of seed beds and to deposit seeds without substantially disturbing the ground between the rows. Another function is to stubble mulch a field or paddock after a crop has been harvested so that the mulch is mixed with the upper layer of the soil. The rotary cultivator assembly 50 may be preceded by a disc coulter assembly 30 and may be followed by a seeder assemby 70 and a plurality of pressing wheels 91 at the rear. <IMAGE>

Description

SPECIFICATION A seeder This invention relates to an agricultural machine, and more particularly the invention relates to a multi-functional agricultural machine of a kind that is drawn across the surface of a field or paddock by a tractor and has a plurality of agricultural tools to work the soil.

According to the present invention there is provided an agricultural machine comprising, a support assembly positioned for rotation about an axis transverse to the direction of movement of the machine, and a plurality of agricultural tools secured to the support assembly, whereby in use as the machine moves overthe ground surface the agricultural tools rotate about the axis and periodically penetrate the ground surface and lift and project soil forwardly thereby to work the soil in a continuous path parallel to the direction of movement of the machine.

It is preferred that the machine further comprises a cover positioned above the support assembly to force soil lifted and projected forwardly by the rotating agricultural tools to fall back to the ground.

Preferably the agricultural tools are secured to the support assembly so that in use the soil is worked in a plurality of spaced apart continuous rows which are parallel to the direction of movement of the machine and which are separated by rows of unworked soil and whereby the agricultural tools form a groove along the length of each continuous row which is substantially filled by loose particles of soil which previously are lifted and projected forwardly by the agricultural tools. With such an arrangement it is preferred that the continuous rows of worked soil comprise less than 30% of the ground surface covered by the machine.

With such an arrangement it is preferred that the agricultural tools are grouped into sets spaced along the length of the support assembly and each set comprises a plurality of agricultural tools spaced radially around the support assembly. Typically each of said agricultural tools comprises a body member and forwardly directed face plate connected to the body member for penetrating the ground surface and lifting and projecting soil forwardly.

In an alternate arrangement it is preferred that the agricultural tools are secured to the support assembly so that in use the soil is worked in a continuous path having a width corresponding substantially with that of the support assembly.

Each of the agricultural tools may be a stubble mulcher. Typically the stubble mulching tool comprises a body member and a plate connected to the body member, the plate extending transverse to the direction of movement of the machine, the orientation of the plate being selected so that as the machine moves over the ground surface the plate rotates about the axis and periodically describes a shallow path through the ground surface with a leading edge of the plate first penetrating the ground surface.

Each of the agricultural tools may also be a cultivator. Typically, the cultivator comprises two plates connected to a central web, and the cultivator is secured to the support assembly so that the plane of the plates is substantially parallel with the direction of the movement of the machine. It is preferred that the plates are angled with respect to each other and to the direction of movement of the machine so that as the machine moves over the ground surface and the cultivator rotates to penetrate the ground surface the soil displaced by the plates is lifted and projected forwardly and outwardly away from the plates.

Embodiments of the agricultural machine will now be described by way of example only with reference to the accompanying drawings in which: Figure lisa plan view of the seeder with some parts removed for clarity; Figure 2 is a sectional view taken along the line 2-2 of Figure 1; Figure 3 is a sectional view taken along the lines 3--3 of Figure 2 illustrating the position and location of disc coulters; Figure 4 is a cross-sectional view taken along the lines 4--4 of Figure 2 illustrating the construction and positioning of one form of agricultural tool relative to elongate runners; and Figure 5 is a cross-sectional view taken along the lines 5--5 of Figure 2 illustrating pressing wheels; Figure 6 is a sectional view of the support assembly of the seeder shown in Figures 1 to 5 illustrating the positioning and construction of another form of agricultural tool for use with the seeder; Figure 7 is a detailed side view illustrating the positioning and construction of another form of agricultural tool for use with the seeder; Figure 8 is a detailed side view of the other side of the form of the agricultural tool shown in Figure 7; Figure 9 is a detailed side view of one form of an agricultural tool for use when the seeder shown in Figures 1 to 8 is converted to operate as a stubble mulcher; Figure 10 is a sectional view taken along the line 1010 in in Figure 9;; Figure 11 is a detailed side view of one form of an agricultural tool for use when the seeder shown in Figures 1 to 8 is converted to operate as a cultivator; Figure 12 is a sectional view taken along the line 12-12 in Figure 11.

The agricultural machine shown in the figures comprises a rotatable support assembly and a plurality of agricultural tools connected to the support assembly to work the soil in a field or paddock. The machine is muiti-functional in the sense that a number of different agricultural tools can be fitted to the machine. One function is to prepare a series of continuous parallel rows of seed beds and to deposit seeds without substantially disturbing the ground between the rows. Another function is to stubble mulch a field or paddock after a crop has been harvested so that the mulch is mixed with the upper layer of the soil. Another function is to cultivate a field or paddock.

The feature common to the machine in each of its operational modes is that the agricultural tools are rotated to periodically penetrate the ground surface and to lift and project soil forwardly thereby to work the soil in a continuous path parallel to the direction of movement of the machine.

The preferred embodiment of the machine will first be described as it is set up to operate in accordance with the first function, i.e. as a seeder.

The preferred embodiment of the machine will then be described in terms of the modifications required to convert the machine to carry out the other two functions, i.e. as a stubble mulcher and as a cultivator.

The seeder illustrated with reference to Figures 1 and 2, comprises a rectangular frame 10 having side bearers 11 and 12, a transversely extending end bearer 13and triangular forward bearers 14 and 15 supporting a central draw bar 16 that is arranged, in use, to be connected to the towing hitch of a suitable towing vehicle such as a tractor. A reinforcing strut 18 extends between the forward bearers as shown in Figure 1. The rectangular portion of the frame is also provided with a pair of spaced transversely extending strengthening struts 108,109 that are described later in the specification.

The frame 10 is supported towards its rear end by an axle assembly 20 that supports a pair of tyre and wheels assemblies 21, 22 to support the seeder and allow the seeder to be drawn across the ground by the towing vehicle. Although not shown in detail, the axle assembly is pivotally attached to the frame and suitable hydraulic or pneumatic rams may be provided between the axle and the frame to cause a change in their angular relationship to, in effect, alter the height at which the seeder extends above the ground surface. The means of raising and lowering agricultural implements such as this is well known to those skilled in the art and is thus not described in detail in this specification.

In essence the seeder is divided into four stations each of which extends transversely across the machine. The first station 30 at the front of the seeder comprises a plurality of flat disc coulters 31, a support assembly on which is mounted a plurality of agricultural tools is positioned behind the coulters to define the second station 50 and the third station 70 that is positioned behind the rotor assembly comprises a seed dispensing mechanism.

The final and most rearward station 90 is in the form of a plurality of pressing wheels 91.

A plurality of longitudinally extending runners 100 are positioned along the length of the seeder from the first station 30 to a position just in front of the fourth station 90. The runners 100 are equally spaced across the seeder to define a plurality of gaps therebetween.

Each runner 100 is an elongate steel section, the cross-section of which is illustrated with reference to Figures 3 and 4. The steel section defines a pair of parallel ground engaging arms 101 and 102 that merge into a closed end 103 that is defined by a pair of inwardly converging wall portions 104 and 105.

As shown in Figure 2 a pair of vertically extending support brackets 106 and 107 are welded or otherwise secured to the closed end 103 of each section, one adjacent the forward end and the other adjacent the rear end. The support brackets are then bolted in an adjustable manner to the transverse support struts 108, 109 of the main frame of the seeder. In this manner the position of each runner 100 relative to the frame is adjustable. It is understood that in the desired orientation the runner is inclined downwardly from the front to the rear of the seeder. As described earlier the runners are equally spaced to define a plurality of longitudinal extending gaps.

Each runner 100 is provided with an open channel section to ensure that the interior space defined by the parallel arms 101, 102 allows debris and projections on the surface of the ground to be accommodated. The debris and other matter collects within the open space of the runner and prevents clogging of the assembly. The comparatively narrow cross-section of the ground engaging portion of the arms 101, 102 ensures passage of the arms over the ground surface as the seeder is drawn across the ground. The comparatively narrow section also has the effect of not disrupting the ground surface unduly and thus breakup of the soil underneath the areas defined by the runners is kept to a minimum.

The first station or coulter station 30 is illustrated in Figures 1 to 3. Fourteen flat disc coulters 31 are mounted to extend one within each gap defined by the runners 100. Each disc coulter 31 is freely rotatable about a spindle 32 that is in turn mounted across down extending flanges 33 and 34 that are welded to a square box section 35 that is in turn adjustably bolted to a transversely extending angle bracket 36 that extends at a position above the main frame as shown in Figure 2. Each disc has a bevelled edge to improve its cutting facility. The means of attachment described above allows the height of each disc two be adjustable.

The second station 50 is illustrated in Figures 1,2 and 4 and comprises a support assembly positioned for rotation about a transverse axis and a plurality of agricultural tools secured to the support assembly.

The support assembly comprises a transversely extending drive shaft 51 that is mounted above the main frame on suitable supports 52 and 53. The shaft is driven via a gear box 54 that is in turn coupled to the P.T.O. of the tractor (not shown). The shaft 51 is welded centrally to a plurality of circular flanges 56 that are spaced to correspond to the spacing of the gaps defined by the runners 100. In the embodiment shown in Figures 1 to 5 there are three agricultural tools bolted to each flange 56.

Each agricultural tool comprises an arm 58 bolted at one end of the circular flange 56 and at the other end to a tine 59 that terminates in a curved pick 60. As shown in Figure 2 a pair of shear bolts 61 are used to secure each arm to the flange and each tine to the arm. The curvatures of the tine 59 and pick 60 are also illustrated with reference to Figure 2. In the embodiment described herein with reference to Figures 1 to 5 the diameter of the tine assembly is forty two inches and the assembly is arranged to rotate at speeds of up to 500 rpm but preferably between 100 to 300 rpm in an anticlockwise direction. As can be seen in Figure 4 this causes the picks 60 to form a groove 62 to a predetermined depth along the axis of each gap defined by the runners.

Although not shown in detail in the drawings the angular orientation of the three arms 58 on one flange 56 to the arms of the adjacent flange is slightly displaced to ensure that at any one time all of the picks 60 do not engage the ground. This means that throughout a single revolution of the drive shaft 51 the picks 60 engage the ground at different times whereby reducing the shock load on the machine and the ground as well as the stress that would be transmitted through the shaft by all the picks 60 engaging the ground surface at the same time.

A half cylindrical steel cover member 64 is bolted to the frame to extend across the area that is taken up by the tine assembly. As the picks 60 engage the ground they throw the displaced earth and other matter forwardly and upwardly into the domed housing causing breakdown of the cut earth into fine tilth particles that then fall down rearwardly of the position, from which the earth was removed as the machine is drawn forward.

The construction and the number of the agricultural tools mounted to each circular flange 56 can be varied as required.

In the arrangement shown in Figure 6 each flange 56 supports six agricultural tools formed in accordance with an embodiment different to that shown in Figures 1,2 and 4. Each agricultural tool comprises an arm 201 bolted at one end to the flange 56 and a pick 203 having a face plate 205 detachably secured to the other end of the arm 201.

The dimensions of the face plate 205 are selected in accordance with the requirements of the seed bed to be formed and the nature of the soil to be worked.

Another embodiment of the agricultural tool is shown in Figures 7 and 8, and it is identical with that shown in Figure 6, with the exception that the arm 201 is in two parts 201a and 201b which are connected together by a pin 207 so that when the face plate 205 contacts a hard object such as a rock the resultant shock causes a lug 209 to be displaced laterally about a pivot pin 211 mounted to the part 201 a thereby to release the part 201 b to pivot rearwardly in a "stump-jump" response to the hard object.

The seed station 70 comprises a three compartment seed hopper 71 that is mounted above and across the seeder as shown in Figure 2. Each sub-hopper terminates in a plurality of downwardly extending seeder tubes 72,73 and 74 that ensure communication from each sub-hopper to each gap defined by the runners 100. As can be noted in Figure 2 the hopper tubes 73 extend downwardly to a forward position just rearward of the path of the cutting tines 59. This sub-hopper would contain a suitable fertilizer. Hopper tubes 72 extend downwardly to a position rearwardly of the first hopper tubes 73. It is understood that this subhopper would hold the primary seeds. Finally hopper tubes 74 extend rearwardly of the other two pipes and it is understood that this sub-hopper may optionally include small pasture seeds.

Although not shown on the drawings, each hopper incorporates an automated seed dispensing device of any kind that would be well known to those skilled in the art. The design and operation of the seed dispensing means is not considered part of the inventive aspect of this seeder and is thus not described in detail in this specification. The seeder mechanism is driven through a sprocket and chain attached to one of the tyre and wheel assemblies 22.

It should however be stated that the seeder would incorporate means to adjust the height at which the outlet ends of the tubes 72,73,74 terminate relative to the ground on which the seeder runs.

The final station or pressing station 90 is illustrated with reference to Figures 1,2 and 5 and comprises a plurality of circular wheels 91 that are mounted just behind the termination of the runners 100 to be co-axially aligned with the gaps between the runners. Pressing wheel 91 is mounted to be freely rotatable about a spindle 92 that is in turn adjustably mounted on the vertical component of a pivotally supported elbow 94 that is secured to the rear cross member 13 to be pivotal thereto about a spring 95 that extends vertically above the elbow 94 and is secured to an upper transversely extending bracket 96. The spring has the effect of forcing the pressing wheel 91 into engagement with the ground surface to provide the desired degree of pressure to compact the soil within the groove formed by the cutting tines.It is understood that the spring force may be adjustable to vary this pressure. As illustrated in Figure 2 an arcuately shaped spring loaded skid 116 is also secured above each wheel to act as a cleaning medium to prevent the wheels clogging. The cross-section of the steel pressing wheels is arranged to be sufficiently wide to satisfactorily suppress the soil within each groove.

As described earlier, each gap defined between adjacent runners, is co-axial with the plane of a disc coulter 31, the plane of rotation of the agricultural tools and the exit aperture of one or more seed dispensing tubes 72,73,74 as well as the plane of a pressing wheel 91. In this manner along each gap defined by the spacing of the runners, there is an opportunity forthe seeder to: (a) cut a slot in the ground surface with the disc coulter, (b) form a seed bed by working the soil in a groove with the counter rotating agricultural tools, (c) place seeds or fertilizer within the seed bed, and (d) press down the seed bed with the pressing wheel.

In use, the seeder is attached to the towbar of a tractor and the P.T.O. of the tractor is coupled to the input of the gearbox that drives the rotor assembly.

On the assumption that the correct adjustment for the various components has been made the seeder is then pulled across the field or paddock to complete the seeding operation. The disc coulters cut a plurality of spaced slots in the surface of the ground. The runners protect the soil adjacent the cut slots, level off debris and cause slight gouging of the surface adjacent the slots as shown in Figure 4. The counter-rotating agricultural tools then gouge out a groove in the ground surface along the line of the slot produced by the coulters. The earth and other matter is thrown upwardly to hit the interior surface of the cover member 64. The earth then falls down in particulate form, contacts the inclined walls of the closed end 103 of the runners 100 that act in the manner of a funnel to cause the earth to fall into the grooves that have been produced by the rotating tines.Thus the grooves are partially filled. At the same time the forward tube from the hopper 71 sprinkles a small portion of fertilizer into the base of the slot. This is then covered by earth from the dome housing, the primary seed tube then deposits seeds at the required interval along the slot, the dispensing of the seeds being synchronised to the speed that the vehicle is moving through the mechanism of the seder. More earth then falls over the seeds substantially filling the groove and at the same time the secondary seed is positioned via the trailing tube from the hopper 71. Finally the pressure wheel runs over the loose earth seeds and fertilizer to compress and form the desired bed for germination of the seeds.

The seeder described above has a number of advantages. Firstly the use of the runners and agricultural tools has the effect of only working on 30% of the soil and thus the seeder makes a perfect seed bed for most root systems with minimum disturbance to the remaining soil. Many agricultural implements can make a desirable seed bed but disturb all the adjacent soil, the result of which leaves the seeds prone to being washed away by rain, swept away by the wind and making the field or paddock very prone to soil erosion. The seed bed described above is produced by leaving 70% of the area untouched and thus there is no break up of the unformed portion of the area and the soil is only worked in the spaced narrow grooves that define the seed bed.

For similar reasons the power requirements of this seeder are low because work is only done on 30% of the soil area.

The design of the counter-rotating agricultural tools within the housing that causes the soil to fall back into the grooves formed by the agricultural tools allows fertiliser to be placed below the seed and the seed to be placed on a bed of finely distributed soil with a small covering of soil compacted by the pressure wheels to leave the desired firmness to maximise germination.

The location of the compacted grooves between untouched portions of the soil also has the effect of allowing rain to penetrate exactly where the seed has been placed whilst at the same time the adjoining soil acts as a wind buff preventing soil erosion. For this reason the seed growth is promoted at a much faster rate that the remainder of the paddock and thus the seeds can be planted amongst weeds and stubble in a field in which stock grazing takes places right up till the shoot penetrates the ground surface. During germination the stock cannot harm the seeds because they are protected within the shallow groove by the untouched 80% of the soil surface.

The use of a relatively large support'agricultural tool assembly that is within a diameter of greater than forty inches provides several advantages namely: a) high rotational velocity at the tips producing a cleaner cut, b) the angle of penetration is quite shallow ensuring minimal soil break-up and a swooping action, and c) the counter-rotation and large diameter means any particular point in the soil is only touched once i.e. there are no multiple passes of the agricultural tools as would happen with clockwise rotation and smaller diameter. The polishing or hardening of the bottom of the groove is avoided thus ensuring good root penetration.

The design of the seeder using the coulters and then counter-rotating agricultural tools allows the machine to be used both in very dry and very wet conditions which obviously improves the flexibility of the machine.

The use of the machine can also be increased because of its ability to sow and cause germination of seeds even into stubble. The machine also has the capacity of allowing the addition of suitable fertilisers or, in extreme situations, moisture at the time that the seed is placed within the groove. The precise location of the grooves and the nondisturbance of the adjacent soil ensures that the ground never crusts on the seed. If the ground is too moist before the seed is germinated the soil tends to shrink in contrast to the adjacent undisturbed surface and allows the shoot to grow healthily between the surface of the unworked ground and the surface of the seed bed.

The seeder described in relation to Figures 1 to 8 can conveniently be converted into a stubble muicher by removing or raising the forward disc coulter and the rearward pressing station, removing the runners, and replacing the agricultural tools with substitute agricultural tools of the type described by example with reference to Figures 9 and 10.

With reference to the figures each agricultural tool for stubble mulching comprises an arm 221 bolted at one end of the circular flange 56 and a transverse lower plate 223 welded to the other end of the arm 221. An upper plate 225 is secured by bolts 227 to the lower plate 223. The leading edge 229 of both plates 223, 225 are formed into sharp edges which are self-sharpening in use due to the orientation of the plates 223, 225 with respect to the ground surface.

The provision of the upper plate 225 minimises the wear on the lower plate 223. It can readily be appreciated that the upper plate 225 can conveniently be replaced when it becomes worn.

The width of the plates 223,225 is selected so that there is only a small gap between adjacent sets of plates 223, 225. As a consequence, in use, substantially the whole of the ground surface over which the stubble mulcher moves is worked.

In use, the cutting height of the plates 223, 225 is adjusted (by operating the hydraulic rams between the wheel assemblies and the frame) so that the plates 223, 225 have a maximum penetration of 2 to 3 centimetres. As a consequence the root systems are substantially undisturbed.

The counter rotation of the blades lifts and projects the soil forwardly into the cover member and breaks up the soil/straw mixture. The soil falls back onto the oncoming straw to place the straw in stress so that the straw shatters thereby allowing far more efficient break up of the straw and soil. As the stubble mulcher moves forward the stubble which is between one and two foot high is bent down forward and present virtually its full length tangential to the circumference of the rotating hoe blades. Apart from the cutting action of the blades themselves the relatively brittle stubble is mulched by the few centimeters of soil and debris being thrown at considerable velocity against it. A large portion of the mulched stubble and soil is thrown-up against the cover member and falls back to the surface leaving a relatively flat layer of stubble and small amount of soil.Seed may also be sown to plant feed for grazing or for other purposes.

The seeder described in relation to Figures 1 to 8 can also conveniently be modified to operate as a cultivator by removing or raising the forward disc coulter and the rearward pressing station, removing the runners, and replacing the agricultural tools with substitute agricultural tools of the type described by example with reference to Figures 11 and 12.

With reference to the figures each agricultural tool for cultivating comprises an arm 251 bolted at one end to the circular flange 56 and a cultivator head 253 connected to the other end of the arm 251. The cultivator head 253 comprises a central web 255 and two plates 257 welded to the central web to extend angled toward each other so that, when viewed from in front of the agricultural tool, the plates 257 diverge rearwardly. The cultivator tools are positioned in sets along the length of the support assembly so that in use substantially all of the ground over which the cultivator is worked. Each set comprises a plurality of the cultivator tools radially spaced around the circular flange 56 of the support assembly. The spacing D of the plates 257 of successive cultivator tools is different.

In use the cutting height of the cultivator tool is adjusted (by operating the hydraulic rams between the wheel assemblies and the frame) so that the plates 257 penetrate the soil up to 10 centimetres or more.

The counter rotation of the cultivator tools causes the plates 257 to periodically penetrate the ground surface and the angle of the plates with respect to each other and the direction of movement of the cultivator lifts and projects the soil forwardly and outwardly into the cover member and breaks the soil into particles. The outward component of movement of the soil also results in collisions between soil projected from adjacent cultivator tools which also helps to break up the soil.

The invention is also not restricted to a machine of the width and size described.

Claims (20)

1.An agricultural machine comprising, a support assembly positioned for rotation about an axis transverse to the direction of movement of the machine, and a plurality of agricultural tools secured to the support assembly, whereby in use as the machine moves the ground surface the agricultural tools rotate about the axis and periodically penetrate the ground surface and lift and project soil forwardly thereby to work the soil in a continuous path parallel to the direction of movement of the machine.

2. A machine as claimed in Claim 1 wherein the agricultural tools are secured detachably to the support assembly.

3. A machine as claimed in Claim 1 or Claim 2 further comprises a cover positioned above the support assembly to force soil lifted and projected forwardly by the rotating agricultural tools to fall back to the ground.

4. A machine as claimed in any one of the preceding claims wherein the agricultural tools are secured to the support assembly so that in use the soil is worked in a plurality of spaced apart continuous rows which are parallel to the direction of movement of the machine and which are separated by rows of unworked soil and whereby the agricultural tools from a groove along the length of each continuous row which is substantially filled by loose particles of soil which previously are lifted and projected forwardly by the agricultural tools.

5. A machine as claimed in Claim 4 wherein the continuous rows of worked soil comprise less than 30% of the ground surface covered by the machine.

6. A machine as claimed in Claim 4 or Claim 5 wherein the agricultural tools are grouped into sets spaced along the length of the support assembly and each set comprises a plurality of agricultural tools spaced radially around the support assembly.

7. A machine as claimed in Claim 4 or Claim 5 wherein each of said agricultural tools comprises a body member and a forwardly directed face plate connected to the body member for penetrating the ground surface and lifting and projecting soil forwardly.

8. A machine as claimed in Claim 7 wherein the face plate is secured detachably to the body member.

9. A machine as claimed in any one of Claims 1 to 3, wherein the agricultural tools are secured to the support assembly so that in use the soil is worked in a continuous path having a width corresponding substantially with that of the support assembly.

10. A machine as claimed in Claim 9, wherein each of said agricultural tools is a stubble mulching tool.

11. A machine as claimed in Claim 10 wherein the stubble mulching tool comprises a body member and a plate connected to the body member, the plate extending transverse to the direction of movement of the machine, the orientation of the plate being selected so that as the machine moves over the ground surface the plate rotates about the axis and periodically describes a shallow path through the ground surface with a leading edge of the plate first penetrating the ground surface.

12. A machine as claimed in any one of Claims 1 to 3 wherein each of the agricultural tools comprise in combination the agricultural tool defined in Claims 7 or 8 and the stubble mulching tool defined in Claims 10Or11.

13. A machine as claimed in Claim 9, wherein each of the agricultural tools comprises a cultivator.

14. A machine as claimed in Claim 13, where the cultivator comprises two plates connected to a central web, and the cultivator is secured to the support assembly so that the plane of the plates is substantially parallel with the direction of the movement of the machine.

15. A machine as claimed in Claim 14, wherein the plates are angled with respect to each other and to the direction of movement of the machine so that as the machine moves over the ground surface and the cultivator rotates to penetrate the ground surface and soil displaced by the plates is lifted and projected forwardly and outwardly away from the plate.

16. A machine as claimed in any one of Claims 4to 8 and 12, further comprising an array of spaced runners extending parallel to the direction of movement of the machine, said runners engaging the ground surface in the spaces separating the said continuous paths, and a seed dispensing mechanism positioned behind the support assembly in the direction of movement of the machine for dispensing seed into the grooves formed by the agricultural tools.

17. A machine as claimed in Claim 16, wherein each runner comprises an elongate steel section of open cross-section defining a pair of ground engaging arms that merge at their upper ends into inclined exterior walls that converge to a closed end.

18. A machine as claimed in Claim 16 or 17, wherein the seed dispensing mechanism is split into a plurality of compartments each of which deposits seeds into the gaps between adjacent runners, the depositing of seeds from each compartment being displaced in the direction of movement of the machine.

19. A machine as claimed in any one of Claims 16 to 18, further comprises a plurality of spaced apart disc coulters positioned in front of the seed assembly in the direction of movement of the machine and arranged to extend between the gaps between adjacent runners to cut slots into the soil as the machine is moved over the ground surface.

20. A machine as claimed in any one of Claims 16 to 19, further comprises a plurality of presser wheels positioned behind the seed dispensing means in the direction of movement of the machine co-axially aligned with the gaps between the runners, and adjustable biasing means to vary the downward pressure that the pressure wheels exert on the worked soil between adjacent runners.