Abstract:
A compression system for a dual material delivery assembly for mounting on a frame alongside a plurality of similar assemblies is described. The assembly includes a furrowing knife for producing a furrow in the ground as it is towed across the ground. A fertilizer tube is mounted behind the furrowing knife. A seed dispensing tube provided is for depositing seed in the furrow behind the fertilizer knife offset to one side and above the fertilizer. A packer wheel is attached to the seed tube assembly. The fertilizer knife and the seed tube assembly are separately mounted on a bracket attached to the implement frame for pivotal movement about a common pivot Two separate cylinders are provided to apply a separate force on the furrowing element and the packer wheel. The cylinders of each of the assemblies are commonly connected for common adjustment on the frame or on the go on a tractor towing the frame.

Description:
This invention relates to a dual material agricultural delivery system for use on a seeder and more particularly to a assembly for mounting and for application of ground biasing forces to the components of the system. It will be appreciated that the term “dual” used herein is intended to include the possibility of more than two materials are delivered either through an equal number of delivery openers or in an arrangement in which one of the openers is used to deliver more than one material. 
   BACKGROUND 
   The use of a single assembly for mounting on a seeder and dispensing both fertilizer and seed in a single pass is known from prior U.S. Pat. No. 4,762,075 of one of the present inventors (Halford) and from subsequent U.S. Pat. Nos. 5,331,907 and 5,398,851 of Beaujot. Also reference is made to U.S. Pat. No. 6,142,085 of Halford et al which discloses another assembly of the same general type using a hydraulic cylinder to provide the necessary forces and U.S. Pat. No. 5,947,209 of Halford et al which shows a construction of shank for use in a machine of this type. 
   These assemblies generally include a furrowing element or knife for producing a furrow in the ground as the assembly is pulled across the ground and a fertilizer feed tube for depositing fertilizer directly behind the furrowing element. A second delivery member including a dispensing tube is provided spaced rearwardly of and usually but not necessarily laterally offset from the furrowing element, for depositing the seed in ground spaced at a position preferably offset to one side from the fertilizer and preferably offset above. A packer wheel then follows for providing depth control and packing soil above the seed. 
   Generally a single biasing element, but in some cases more than one such element, is provided in the above arrangements for urging both the furrowing element and the packer wheel downward to engage the ground. In some known assemblies however the forces are more directed to one element rather than the other. When the forces are not properly distributed, taking into account the ground conditions which may vary widely, the resulting seeding operation becomes less effective. The above patent U.S. Pat. No. 4,762,075 of Halford provides an arrangement using a spring for applying force to the knife and a separate spring for applying forces to the packer and second delivery member. In practice both are adjustable to provide independent adjustment of the separate forces for best control. The above patents of Beaujot provide instead an arrangement using a hydraulic cylinder to apply the force. However these do not allow the distribution of force between the packer wheel and the second distribution member on one assembly and the furrowing element or knife on a second assembly to be adjusted independently and thus the seeder is less suited to varying conditions of the ground to be seeded. 
   A research machine which was used in the 1960s in Sweden was developed by researchers Heinonen and Huhtapalo provided an arrangement generally of the above type which included a first furrowing element for engaging the ground and for applying fertilizer and the second furrowing element behind and offset to one side from the first for applying seed with the second attached to a packer wheel for guiding the depth of the seed. This machine known as the “Viktoria” machine was used for research but did not lead to any commercial machines of that type with the commercial development arising from the research being directed to alternative types of machines known as “mid row banding”. The Viktoria machine mounted the fertilizer element and the seeding/packer element as separate components on a frame with a hydraulically biased rocker shaft applying forces onto the fertilizer component and a spring connected between the packer arm and the frame providing biasing forces on the packer wheel. Drawings of this device are shown in a paper entitled FERTILIZER PLACEMENT FOR SMALL GRAINS by HEINONEN et al dated 15 th  Apr. 1978. 
   Machines of the above type shown in the Halford and Beaujot patents are generally used for single pass, minimum-tillage seeding and fertilizing. Machines of this type have become widely used and are manufactured under the arrangements as shown in the above patents by the companies Conserva Pak and Seed Hawk. While machines of this general type and as disclosed herein are primarily proposed for minimum tillage applications, it is not essential that they be so used and in many cases the same machine can be used in tillage systems where the conditions of crop residue and soil impaction are less rigorous. 
   A number of further devices, one example of which is shown in U.S. Pat. No. 5,562,054 of Ryan issued Oct. 8, 1996, include a furrowing element which is engaged into the ground by force from the hydraulic cylinder. The second material delivery system is pivotally mounted on the rear of the shank and floats on a parallel linkage system with a relatively small spring force applied by a mechanical spring. An arrangement of this type has some application in relatively light soils but is unsuitable for wide application and for zero till applications. 
   SUMMARY 
   It is one object of the present invention to provide an improved dual (two or more) material delivery assembly for placing agricultural materials in or on the ground. 
   According to one aspect of the present invention there is provided an apparatus for delivering agricultural materials to the ground comprising: 
   a frame which is supported for movement in a forward direction over the ground; 
   a plurality of delivery assemblies mounted on the frame at spaced positions across the frame for delivering the agricultural materials to the ground at spaced positions across the ground as the frame moves over the ground; 
   each delivery assembly comprising: 
   a mounting bracket attached to the frame; 
   a furrow forming element extending generally downward from the bracket to a ground penetrating end arranged to penetrate the ground for producing a furrow as the frame is moved across the ground in the forward direction; 
   the furrow forming element being pivotally mounted on the mounting bracket for pivotal movement relative thereto about a furrow forming element axis which is horizontal and transverse to the forward direction; 
   the furrow forming element including a first material delivery conduit located behind the ground penetrating end of the furrow forming element for depositing a first material in the ground rearward of the ground penetrating end of the furrowing element; 
   a second material delivery member including a second delivery conduit spaced rearward from the furrow forming element and the first material delivery conduit, the second material delivery member having a ground engaging end for depositing a second material in the ground at a position spaced from the first material; 
   the second material delivery member being pivotally mounted on the mounting bracket for pivotal movement relative thereto independently of the pivotal movement of the furrow forming element about a second material delivery member axis which is horizontal and transverse to the forward direction; 
   a first force application member connected between the bracket and the furrow forming element for providing a force on the furrow forming element for urging the furrow forming element about the furrow forming element axis to engage the ground; and 
   a second force application member connected between the bracket and the second material delivery member for providing a force on the second material delivery member for urging the second material delivery member about the second material delivery member axis to engage the ground. 
   Preferably the mounting bracket is fixed to the frame, but it may be free to float or move relative to the frame for example on parallel links. 
   As set forth above, the above apparatus may include the delivery of more than two materials either using more than two delivery systems or by delivering two materials in one of the delivery systems. 
   For example, the second material delivery system could include two elements one on each side of a furrow formed by the first delivery system. 
   Where it is stated above that the bracket is fixedly mounted on the frame, this is intended to include the possibility that it can be readily removed and replaced for example by way of clamping bolts or that it is permanently attached to the frame. The term is intended to be restricted to the fact that the bracket remains fixed in place on the frame during use of the system. 
   The furrow forming element and the second material delivery member may be similar in construction or may be of different constructions and the use of different terms for these elements is not intended to imply any specific construction. 
   Preferably there is provided a packer wheel which is mounted on either the furrow forming element or the second material delivery member for engaging the ground. In this way the depth of operation of that element is controlled by the packer wheel. The depth of the other element may be controlled by the height of the frame, but other methods of control may be used. Where the furrow forming element forms the primary furrow and the second element merely runs primarily in the formed furrow, the major forces from the ground are communicated through the furrow forming element so that preferably the packer wheel is attached to the second element rather than the furrow forming element. 
   Preferably there is provided two stop members each of which is mounted on a respective one of the furrow forming element and the second material delivery member for halting downward movement thereof relative to the bracket. In this way the elements can be prevented from over extending the force application members and can be lifted from the ground by lifting the elements themselves or the frame for transport. 
   Preferably the first and second force application members each comprise a fluid actuated cylinder which preferably uses hydraulic fluid for higher pressures, but may use air or other fluid. 
   In one particularly preferred arrangement, the second material delivery member is arranged to be offset laterally and upward from the ground penetrating end of the furrow forming element, which is preferably a knife or narrow hoe opener, for engaging a side of the furrow while running primarily within the furrow and depositing the second material in the ground spaced upward and laterally offset from the first material. Thus the second material delivery member is also preferably narrow so as to deposit the second material substantially in the furrow substantially without increasing the width of the furrow. This construction is particularly applicable for zero till applications. However other arrangements and other furrow forming elements may be used including sweeps, disks, and shovels. 
   Preferably the first and second force application members are arranged in substantially a common plane at right angles to the frame with one in front of the other. 
   Preferably the first and second force application members are located and arranged relative to the respective pivot axis so as to provide a greater mechanical advantage for the furrow forming element than for the second material delivery member. 
   Preferably the furrow forming element axis and the second material delivery member axis are coaxial about a common axis. 
   Preferably the first force application member is located at a greater distance from the common pivot axis than the second force application member so as to provide a greater mechanical advantage for the furrow forming element than for the second material delivery member. 
   Preferably the first and second force application members each comprise a fluid actuated or hydraulic cylinder of the same dimensions. This arrangement is convenient mechanically and can be used to provide the different forces required due to the different spacing providing different mechanical advantage but is not essential to the construction since different cylinders can be used. 
   Preferably the bracket comprises a pair of substantially parallel side plates with the first and second force application members located between the plates. The term “plates” used herein can include a cast structure forming a hollow area between two side portions and is not intended to be limited to fabricated elements. 
   Preferably the first force application members of the assemblies are interconnected to a first common adjustment system for common adjustment of the force applied thereby and wherein the second force application members of the assemblies are interconnected to a second common adjustment system for common adjustment of the force applied thereby. 
   Preferably the frame is arranged for connection to a tractor and wherein one or both of the first and second common adjustment systems are located on the tractor for adjustment on the go. 
   In the alternative, one or both of the first and second common adjustment systems are located on the frame. 
   Preferably one or both of the first and second common adjustment systems comprises a fluid accumulator located on the frame. 
   The mounting bracket preferably has the following features or options: 
   1. Single point of attachment to a frame. 
   2. Contains a single pivot point about which the two (or more) soil engaging components can rotate. 
   3. Contains mounting for at least two force generating mechanisms which are centrally adjustable for the complete machine. 
   The First Opener preferably has the following features or options: 
   1. Can pivot from the single pivot point attached to the mounting bracket. 
   2. Can be any type which provides a first opening in the soil to enable placement of one or more products onto or in the soil. 
   3. The depth and location of the first opener in the soil can be determined by the frame and/or any other depth locating or influencing means. 
   4. Has its own centrally adjustable force mechanism. 
   5. Can have one or more delivery means to transport product(s) as required on or into the soil as required. 
   6. The first opener can have any approach angle to the soil as required for the task. 
   The Second material delivery member can preferably have the following features or options: 
   1. At least some parts pivot from the single pivot point on the mounting bracket. 
   2. Can be of any type which provides a second engaging of the soil as required to place product(s) on or into the soil. 
   3. Depth and position can be determined by the frame, packer wheel, shoe and/or any combination or other device as required. 
   4. Has its own centrally adjustable force mechanism. 
   5. Can have one or more delivery means to transport product(s) as required on or into the soil as required. 
   6. Position of placement of products by the second opener can be:
         a) With the product(s) delivered by the first opener delivery means.   b) Above the location of the first opener delivery position   c) To one side of the first opener delivery position   d) To one side and above the first opener delivery position   e) To each side of the first opener delivery position   f) To each side and above or below the first opener delivery position.       

   7. The second opener can be any of the following:
         a) Fixed vertically &amp; horizontally   b) Fixed horizontally—vertical is variable   c) Fixed vertically—variable horizontally   d) Variable vertically and horizontally.       

   8. The second opener could be both a depth controlling and product delivery means. 
   9. The second opener can operate within the furrow created by the first opener or outside of the furrow created by the first opener. 
   10. The second opener can have any approach angle to the soil as required for the task. 
   The packer wheel if used preferably has the following features or options: 
   1. Can be rigidly attached to the second delivery member. 
   2. Can pivot relative to the first opener but from the same pivot point. 
   3. In the alternative the packer wheel could be rigidly attached to the first opener and pivot relative to the second opener. 
   4. In a further alternative the packer wheel could pivot relative to both the first and second opener. 
   5. There may be no packer wheel or other gauging and/or packing device. 
   6. The dimensions and/or shape of the packer wheel or other gauging and/or packing devices can be as required to optimize crop planting results with a minimum soil disturbance planting system in conjunction with selected opener devices. 
   7. The packer wheel or other soil engaging component such as a skid member or the like can be longitudinally fixed relative to the first and/or second opener or be able to move from side to side as required. 
   The force application members preferably have the following features or options: 
   1. The force for any of the components can be provided by a single system with similar system forces (PSI) and with a single adjustment. 
   2. The force for each component can be provided by separate force generating systems which provides completely independent adjustment and setting. 
   3. The adjustment of forces can be provided by a single system which can adjust the forces on the first opener in the first instance and then adjust the forces on the, further soil engaging components in a separate step or steps. 
   4. The force control system can be provided by a system independent of the tractor. 
   5. The force control system can be fully provided by the tractor. 
   6. The force control system can be partially independent of and partially dependent on the tractor. 
   7. The pressure system can be operated with either a continuously generated pressure supply (i.e. live hydraulics, air etc.) or with a non-continuous pressure supply (accumulator, pressure tank, and/or other intermediate pressure storage system.) 
   8. The pressure system could be hydraulic, air or other fluid systems. 
   9. The pressure system for the complete opener assembly could be a combination of hydraulic, air or other systems. 
   The pivot arrangement preferably has the following features or options: 
   1. Furrow forming element can pivot:
         Relative to the frame   With the second and other soil engaging components.       

   2. Second material delivery member can pivot
         Relative to the frame   Relative to the furrow opener       

   3. Different components can pivot relative to each other but not be tied to each other. 
   4. Different components can pivot independent of each other. 
   The arrangement as described in detail hereinafter may provide one or more of the following features: 
   1. Independent Force Mechanisms for two or more soil opener systems which is centrally adjustable. 
   2. Central adjustment can be either while stopped and adjusting settings or while the unit is in motion (i.e. on the go adjustability) 
   3. The force system can be relatively fixed on one opener system and remotely adjustable on the other opener system(s) during operation. 
   4. The centrally adjustable force system can accommodate a wide range of different soil opener combinations with widely differing force requirements i.e. low, medium and high draft requirements. 
   5. The opener systems can accommodate a range of cropping requirements which require different locational placement of one product relative to one or more other products. 
   6. The same force and linkage means can accommodate a wide range of soil openers and/or soil opener combinations. 
   7. The forces on a first opener system can be centrally adjusted in the same direction as the forces on other openers or soil engaging components. Alternatively the forces on other openers can be adjusted opposite to the forces on the first opener. 
   8. Pivotal movement is allowed between the first opener and any other soil engaging components and where the forces on each part of the first opener and other soil engaging components is centrally adjustable as required. 
   9. The first opener and any other soil engaging components all pivot from a common pivot point but with separate and independently adjustable force systems. 
   The arrangement as described in detail hereinafter may provide one or more of the following advantages: 
   1. With independent force mechanisms each opener system can have its force adjusted independent of the other opener at a central point. 
   2. Adjustment can be a simple independent and self contained force system or from an existing power unit such as a tractor. 
   3. An operator can adjust each opener system for the soil, moisture and crop requirements as well as any ground obstacles as required. One or more systems can be adjusted “on the go”. 
   4. A simplified force system on a soil opener enables the operator to utilize the complete implement in a wide range of soil conditions. 
   5. The simple opener and force systems can accommodate a wide range of cropping situations. 
   6. A single opener linkage and force system could be used by an operator with differing actual, soil opener(s) or with a specific fixed set of opener styles. 
   7. An operator can achieve the required force levels on each part of the total opener system as required for soil engaging components in a given field and cropping situation. 
   8. The pivotal movement of the first opener system relative to any other soil engaging components allows each part of the total system to operate with optimum depth and force as required. 
   9. The common pivot point simplifies the design and apparatus while still permitting independent pivoting of different adjustable forces. 
   In further embodiments the hydraulic piston cylinders may be replaced with pneumatic cylinders or springs. The pneumatic cylinders and springs can also provide a constant force on the knife and wheel support members while allowing the members to deflect upward in response to ground contours or obstacles in the ground as the assembly is pulled across the ground. 
   While the second material delivery member is shown hereinafter in effect as only a tube with its lower end engaging the ground, the member may include more structural elements including reinforcing elements on the tube or a second knife which carries a flexible tube thereon. 
   While the arrangements described hereinafter include only a single second delivery member for depositing seed to one side of the fertilizer, alternative arrangements can include a third seed delivery tube arranged symmetrically relative to the second tube on the opposite side for dual seed delivery. Such arrangements are previously known and where this application refers to a second delivery member, it will be understood that two such second delivery members may be included in the construction described. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings, which illustrate exemplary embodiments of the present invention; 
       FIG. 1  is a side elevational view of one embodiment of the dual material delivery assembly according to the present invention, showing the elements in operating position on the frame. 
       FIG. 2  is a top plan view of the embodiment of  FIG. 1 . 
       FIG. 3  is a side elevational view of a part only of the embodiment of  FIG. 1  showing only the furrow forming element. 
       FIG. 3A  is a top plan view of the components of  FIG. 3 . 
       FIG. 4  is a side elevational view of a part only of the embodiment of  FIG. 1  showing only the second delivery member. 
       FIG. 4A  is a top plan view of the components of  FIG. 4 . 
       FIG. 5  is an isometric view of the embodiment of  FIG. 1 . 
       FIG. 6  is a side elevational view of the embodiment of  FIG. 1  in a raised tripped position by engagement of the knife with an obstacle. 
       FIG. 7  is a schematic illustration of a first control circuit showing the frame, a tractor to which the frame is attached and the control system for varying the force applied to the elements on the go. 
       FIG. 8  is a schematic illustration of a second control circuit showing the frame, a tractor to which the frame is attached and the control system for varying the force applied to the elements by manual operation on the frame at a central location. 
   

   DETAILED DESCRIPTION 
   The complete machine including the frame arranged for attachment to a tractor is shown in  FIGS. 7 and 8  and in the remaining figures only one portion of the tool bar of the frame is shown. The frame can be of a conventional nature providing one or more toolbars arranged at right angles to the direction of movement with the toolbar or tool bars including appropriate arrangements to allow suitable spacing of the ground engaging elements as is well known to one skilled in the art. The frame may be of a type which is arranged so that its height can be adjusted or changed for varying the depth of operation of the ground engaging element or for lifting the ground engaging element from the ground. However frames with a fixed height can also be used. 
   One toolbar is indicated at  10  in  FIG. 1  and to which is mounted a bracket  11  using conventional U-shaped clamping bolts  12 . On the bracket  11  is mounted firstly a furrow forming element  13  which is mounted for pivotal movement about a pivot member  14 . Also mounted for pivotal movement about the pivot member  14  is provided a second ground engaging element  15  including a second delivery member  16  and a packer wheel  17 . The furrow forming element  13  includes a material delivery tube  18 . The second material delivery member  16  includes a tube  19  and a mounting system  20 . 
   The tubes  18  and  19  may be of the same construction or may be of different construction as required. The tube  18  may be of a flexible hose type nature since it is supported directly on the rear of the furrow forming element  13 . The tube  19  as shown comprises a rigid tube structure which is unsupported by additional elements. However it may also be formed as a flexible hose with a supporting front member which may be similar to the furrow forming element  13  or may be of a reduced structural nature depending upon requirements. 
   The furrow forming element  13  is biased into engagement with the ground by a first force application member  21  and the second ground engaging element  15  is biased downwardly toward the ground by a second force application member  22 . In the embodiment shown, both of the force application members are formed from cylinders with a suitable fluid, in most cases a hydraulic fluid, applying pressure to the system within the cylinder to bias the respective element toward the ground. 
   The arrangement as shown is of the type shown in the above mentioned Hatford U.S. Pat. No. 4,762,075 so that it includes a furrow forming element including a first material delivery conduit, a second ground engaging member including a second conduit and a packer wheel which are arranged in a row one generally behind the other and mounted from a common mounting on the frame. The construction as shown herein therefore may take many of the features and components described in the above mentioned Halford patent, the disclosure of which can be referred to for further details of the structure disclosed herein. 
   However the arrangement as shown can also be modified in many different ways to incorporate different components and different spacings. 
   In  FIGS. 3 and 4 , it will be noted that for convenience of illustration each of the furrow forming element  13  and the second engaging element  15  are shown separately so that the respective components can be seen more easily in the side elevational view. 
   Thus turning firstly to  FIGS. 3 and 3A  the shape and arrangement of the brackets can be seen in most detail. Thus the bracket comprises a flat plate  23  which lies against the rear surface of the frame toolbar  10  and is clamped onto that rear surface by two U-shaped bolts  12  which extend through holes in the plate and are held in place by nuts  24 . The bracket further comprises a pair of upstanding main support plates  25  which extend upwardly above the plate  23  to a top edge  26 . The plates  25  are at right angles to the plate  23  and extend rearwardly from the plate  23  that is to a position behind the toolbar  10 . The plates  25  also extend downwardly below the plate  23  and rearwardly from the plate  23  to a bottom apex  27 . The bottom apex is thus spaced below the tool bar  10  by a distance sufficient to receive the pivot mounting member  14  which spans across between the plates. From the apex  27 , the plates  25  extend upwardly and forwardly along a bottom edge  28  to a front edge  29  underneath the toolbar  10 . 
   The bracket  11  further includes a tongue  30  which extends from the plate  23  underneath the toolbar  10 . The bracket  11  further includes a pair of side members  31  which are bolted to the front portion of the side plates  25  underneath the toolbar  10  at a coupling  32  and extend therefrom downwardly and rearwardly to the pivot  14 . Each of the members  31  is cranked so that it extends outwardly away from the plate  25  to accommodate the full length of the pivot member  14  which projects through the plates  25  outwardly beyond the plates  25  to provide support for the second ground engaging member  15  as described in more detail hereinafter. 
   The pivot member  14  is thus mounted on the members  31  and on the plates  25  and extends horizontally there across at a position just underneath and rearwardly of the tool bar  10  and provides pivotal support for both the furrow forming element as shown in  FIGS. 3 and 3A  and for the second ground engaging member as shown in  FIGS. 4 and 4A  and described in more detail hereinafter. 
   In  FIGS. 3 and 3A , the furrow forming element comprises a pair of mounting plates  33  which clamp between them the main shank  34  of the furrow forming element. The plates  33  extend to a portion  35  mounted on the pivot member  14 . The plates  33  also extend rearwardly beyond the pivot member  14  to an abutting portion  36  which is arranged to engage the tongue  30  in the downward position of the ground engaging member that is the position which is the furthest position which the ground engaging member can reach in the clockwise direction of turning around the pivot  14 . The plates  33  are also bent outwardly at the top to form a device  36  for receiving a lower end  37  of the piston of the cylinder  21 . A pin  38  extends across the two sides of the device  36  and connects the piston rod  37  to the plates  33 . An upper end of the cylinder  21  is attached by a transverse pin  39  to the plates  25  at an upper rearward apex  40  thereof. 
   The cylinder  21  is a single acting cylinder acting to push downwardly on the device  36  of the plates  33  so as to bias the shank  34  in the clockwise direction around the pivot  14  for engagement of the furrow forming member into the ground. 
   The shank  34  carries a knife  41  and carries the tube or conduit  18  both in conventional manner. The shank and knife construction are generally of the type shown in the prior U.S. Pat. No. 5,947,029 of Halford so that both the knife and the shank are formed from a plate which is cut to shape and provides sufficient rigidity to prevent side to side bending of the shank and the knife during action but allows same flexibility. However conventional knife constructions can be provided which bolt onto the shank in a conventional manner. 
   Counterclockwise or lifting movement of the ground engaging member is halted at a predetermined position also by a suitable stop arrangement. The stop can be provided at any suitable location on the structure but in the example shown is provided by a first abutting member  43  on the shank  34  which butts against a projection  44  mounted on the plate  23 . 
   The angle of the cylinder  21  relative to the device  36  and the mounting pin  40  is such that it tends to move along an arc around an axis defined by the pivot member  14  and to push generally along a tangent to that arc. 
   Turning now to second ground engaging element as shown in  FIGS. 4 and 4A , this generally comprises a pair of arms  50  which are located outwardly of the plates  33  of the furrow forming element and outwardly of the plates  25  of the bracket so as to be mounted on the pivot member  14  at the outer ends thereof for pivotal movement about the same axis as the pivotal movement of the furrow forming element as defined by the pivot member  14 . The arms  50  extend from the pivot member  14  downwardly and rearwardly in a straight line to a bottom end  51  at which is located at a bearing  52  for the packer wheel  17 . Thus the arms  50  can generally pivot upwardly and downwardly and their height is controlled by the engagement of the packer wheel  17  on the ground. 
   Between the arms  50  is mounted the tube  19  on the mounting assembly  20 . The tube  19  is mounted for adjustment movement in a horizontal side to side direction relative to the arms  50  and also in a vertical up and down direction relative to the arms  50 . This mounting includes a mounting block  53  on which the tube  19  is carried for side to side movement by adjustment of suitable mounting bolts  54 . The block  53  is carried on a pair of side arms  55  which lie along the inside surface of the arms  50  up to a mounting pin  56  adjacent to but spaced downwardly from the pivot pin  14 . Thus upward and downward movement of the block  53  relative to the arm  50  is controlled by pivotal movement of the arms  55  which are then attached to the arms  50  at a suitable location by application through selected ones of mounting holes of a pin. 
   The arms  55  could be omitted and the block  53  mounted directly on the arms  50 . However the presence of the arms  55  allows the adjustment to be effected more quickly and more simply since the block  53  is not loose between the arms  55  when the pin  57  is removed but is held in place on pivots in a controlled manner upwardly and downwardly until the pin  57  is replaced at the required location. 
   The arms  50  also carry actuating arms  60  which extend therefrom upwardly to co-operate with the cylinder  22  and with the plates  25  of the bracket  11 . Thus the arms  60  include a first portion  61  which carry a pin  62  connected across the lower end of the piston rod  63  of the cylinder  62  for application of force from the cylinder  22  in a clockwise direction onto the second ground engaging member around the pivot member  14 . Also the actuating arms  60  include a second portion  65  extending upwardly and rearwardly from the portion  61  with the portion  65  carrying a locating pin  66  which connects between each of the arms  60  and the respective plate  25 . A slot  67  in the plate  25  acts to control the length of movement of the actuating arm  60  and therefore the extent of pivotal movement of the arms  50  around the pivot member  14 . 
   The tube  19  can comprise a simple rigid tube or can comprise a flexible tube supported by a structural member. Also the tube can be of a construction shown in the early Halford U.S. Pat. No. 4,762,075. A further design of shank which can be used is shown in the above U.S. Pat. No. 5,947,209 of Halford et al. Further details of this construction can be obtained from one or other of the above patents. Other designs can also be used as will be well known to one skilled in the art. 
   The cylinder  22  thus provides a biasing force on the arms  60  thus tending to press the packer wheel onto the ground to a predetermined pressure as controlled by adjustment of the pressure on the cylinder  22 . It will be noted that the cylinder  22  is located at a shorter radial distance from the pivot  14  relative to the cylinder  21  so that the mechanical advantage obtained by the cylinder  21  is greater than that obtained by the cylinder  22  thus applying a greater force at the same pressure. The pressure can of course be adjusted independently but the greater mechanical advantage is provided so that the primary force applied to the system is through the furrow forming element. The two cylinders are mounted on a common plane at right angles to the tool bar  10  and located between the plates  25  of the bracket. The cylinder  22  is inclined downwardly and rearwardly to a greater angle than the cylinder  21  in order that the force applied to the arms  60  is primarily tangential to the arc of movement thereof around the pivot  14 . 
   Turning now to  FIG. 7 , there is shown schematically the construction of the implement including a part of the frame and the tractor. Each of the ground engaging elements (not shown for convenience of illustration) is of course of the construction as previously described and is mounted on the tool bar of the frame at the required location to provide the spacing desired for the seeding system. The frame portion shown is the hitch portion for connection to a conventional tool bar which includes components for supplying the first and second materials to the tubes  18  and  19  which is not shown for convenience of illustration. 
   What is shown is the adjustment system for the pressure applied to the cylinders  21  and  22 . In  FIG. 7  this is shown as an arrangement including adjustable valves  121  and  122  mounted on the tractor for on the go adjustment. The fluid from the tractor mounted valve  121 ,  122  is supplied to an accumulator  124 ,  127  the pressure of which is monitored by a gauge  123 ,  128 . The adjustment can be provided for only one of the sets of cylinders. Thus for example the pressure applied to the cylinders  21  for the furrow forming element can be adjusted on the go by the valve  121  and the pressure applied to the cylinders  22  for the packer wheels can remain at a fixed condition. The system can also be set up for the opposite adjustment. 
   In  FIG. 8  is shown an arrangement in which adjustment is effected centrally but periodically. Thus each of the sets of cylinders  21  and  22  has an accumulator  124 ,  127  as previously described. However the accumulators are connected to a hand pump  125  and a hydraulic control block  126  which controls the pressure from the tractor hydraulics or the hand pump to provide a fixed but adjustable pressure to each of the accumulators  124  and  127  for the cylinders  21  and  22 . Thus the operator can adjust the amount of pressure by adding or releasing gas from the accumulators  124 ,  127  independently. In the embodiment shown in  FIG. 8  the cylinders  21  are connected to a common accumulator  124  and the cylinders  22  are connected to a common accumulator  127 . These accumulators can be independently adjusted for independent adjustment of the cylinders  21  and  22  respectively. Alternatively one of the sets of cylinders can be adjusted by an accumulator on the frame and the other adjusted on the go by connection to a valve  121 ,  122  on the tractor as previously described. 
   While some embodiments of the present invention have been described in the foregoing, it is to be understood that other embodiments are possible within the scope of the invention. The invention is to be considered limited solely by the scope of the appended claims.