Abstract:
Transplanter which can avoid skips when planting, which skips may occur when seeds in a tray row fail to grow into seedlings. This is accomplished by picking up an entire row of seedlings from a tray, transferring the seedlings to a mechanism which eliminates gaps between seedlings, and then discharging the seedlings one at time to the ground with a desired spacing between the seedlings. A novel tray indexing mechanism is provided which can index trays of varying sizes. The planting mechanism has an air knife mounted adjacent transfer disks for straightening out the foliage as stems of seedlings before they are received by the planting disks, and the planting and transfer disks may be moved towards and away from each other for seedlings of differing heights.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit under 35 U.S.C. § 119(e) of U.S. provisional patent applications Ser. No. 60/963,645, filed Aug. 4, 2007, Ser. No. 60/998,329, filed Oct. 10, 2007, and Ser. No. 61/067,575, filed Feb. 29, 2008 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates generally to transplanters, and more particularly to one which can avoid skips when planting which may occur when seeds in a tray row fail to grow into seedlings. This is accomplished by picking up an entire row of seedlings from a tray, transferring the seedlings to a mechanism which eliminates gaps between seedlings, and then discharging the seedlings one at time to the ground with a desired spacing between the seedlings. 
       BACKGROUND OF THE INVENTION 
       [0003]    Transplanters are well known in the art. U.S. Pat. No. 6,327,986 discloses an apparatus for transplanting seedlings from nursery trays. This approach utilizes a specially designed tray with grooves evenly spaced across the tray top for a sprocket-type element to engage and incrementally advance the tray one row at a time into the extraction area. At the extraction area, a row of plunger devices engage the tray and push one row of plants at a time from the tray into an endless belt equipped with a series of chambers that are matched to the same pitch center of the tray. After extraction, the loaded root ball chambers and belt assembly are rotated 90° from the face of the tray. The plants are then discharged, one at a time, into a series of interlocks that convey the plants to the ground engaging row unit. Along the way, three separate sets of sensors look for plant skips and advance the root ball chamber belt assembly one cell to make up for skips and eject the deficient root ball at the same time. 
         [0004]    U.S. Pat. No. 6,080,951 discloses another approach to overcome the seedling tray skip problem. This concept utilizes a system, whereby two sets of plungers and extractors remove plants simultaneously from a plant tray. On a 10 cell tray, the first extractor would be positioned at the No. 1 cell and the second at the No. 6 cell. After extraction, the plants are dropped into two separate gated chambers and sensors confirm that plants are present. In normal operation, the plants would discharge sequentially from each chamber. If a skip is detected, the deficient root ball would be discarded and the other root ball would be planted in its place. 
         [0005]    These approaches rely heavily on the accuracy of detectors to sense the presence of plant foliage. Considering the chaotic nature of the foliage and the necessary speed to be efficient, there is substantial room for error in these systems. Our system, by nature of its design, has no sensors, no extra extraction points or extra mechanics. All the tray skips are overcome by the belts pushing together the root balls of the rows of plants extracted from a plant tray. 
         [0006]    Other transplanters which transplant from a plant tray are shown in U.S. Pat. Nos. 4,644,880; 5,431,116; 5,573,558; 5,676,072; 6,073,564; and 6,634,306. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0007]    It is an object of this invention to provide a method for transplanting seedlings grown in trays having a plurality of side-by side rows of seedling cells, which method plants the seedlings uniformly apart even though not all cells have seedlings. The method includes the steps of picking up an entire row of seedlings from a tray, which row may have gaps between seedlings, transferring the seedlings to a mechanism which eliminates gaps between seedlings, and then discharging the seedlings one at time to the ground with a desired spacing between the seedlings. The seedlings have a root ball, stem, and leaves or foliage. 
         [0008]    It is a further object of this invention to provide an apparatus for transplanting seedlings grown in trays having a plurality of side-by side rows of seedling cells, which apparatus plants the seedlings uniformly apart even though not all cells have seedlings, the apparatus including means for picking up an entire row of seedlings from a tray, means for eliminating gaps between seedlings, and means for discharging the seedlings one at time to the ground with a desired spacing between the seedlings. 
         [0009]    It is a further object of this invention picking up an entire row of seedlings from a tray by engaging the stems of the seedlings, which row in the tray may have gaps between seedlings; to transfer the seedlings to a mechanism which eliminates gaps between seedlings; to discharge the seedlings one at time from the gap eliminating mechanism with a desired spacing between the seedlings; and to plant the seedlings uniformly apart in the ground. 
         [0010]    It is another object of the present invention to provide a transplanter which discharges seedlings one at time to the ground with a desired spacing between the seedlings, the transplanter having an improved planter assembly having a forward pair of transfer disks; a rear pair of planter disks; and an air knife mounted adjacent the forward pair of transfer disks for extending the stem and foliage of a seedling while in the forward pair of transfer disks for proper engagement by the rear pair of planting disks. 
         [0011]    It is yet another object of the present invention to a transplanter which discharges seedlings one at time to the ground with a desired spacing between the seedlings, the transplanter having an improved plant feeder subassembly including a forward pair of transfer disks; a rear pair of planter disks; and means for moving the pairs of disks towards and away from each other to accommodate differing seedling heights. 
         [0012]    A further object of the present invention is to provide a nursery tray indexing mechanism for use in a transplanter which discharges seedlings one at time to the ground with a desired spacing between the seedlings, which transplanter picks up an entire row of seedlings from a tray, which indexing mechanism is capable of receiving nursery trays of differing depths, widths, lengths and spacings between adjacent rows of cells, the indexing mechanism having top and bottom holding rails for slidably receiving and holding nursery trays; means for indexing the tray a distance approximately the width of a nursery tray cell; and means to finally position the tray by engaging a cell. 
         [0013]    Our approach utilizes a series of rubber grippers that engage the edge of the tray and advance the tray a distance approximately the width of one cell. Then a cone-shaped or V-shaped tray locking device engages an adjacent cell and accurately locates the cells to the proper location. This concept eliminates the need for special trays and retains the precision accuracy of indexing. When changing to different cell-sized trays, the position of the tray locking device is the only adjustment necessary. 
         [0014]    To extract a row of plants, a spear device is utilized which penetrates across the top of the tray, capturing a row of plants by their stems. A bladder tube is then inflated, pinching the stems between the spears. With the tray in a vertical position, the spear extracts one row of plants and rotates down. This concept eliminates the need to engage the tray, thereby eliminating unnecessary sophistication and accuracy needed in the plunger type concept. Extracting the plants by gripping the stems and leaves of a root ball is much less invasive to the root ball, whereas the plunger concept compresses and damages the end of the root ball extensively. With the spear extraction concept, all the deficient root balls are left in the tray. 
         [0015]    For gap-up of skips, the row of inverted plants is placed on a pair of gap-up belts that run faster than the discharge rate, thereby pushing up any skips in the row of plants. No electronics and no sensors are needed in this configuration, thereby increasing the accuracy and reducing any unnecessary sophistication of the system. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES  
         [0016]    In the following views right hand and left hand reference is determined by standing behind the transplanter and facing its direction of travel. In addition, for convenience, front and rear references are applicable to a single row transplanter as shown in  FIG. 1A . 
           [0017]      FIG. 1A  is a left side elevational view of a one row transplanter of this invention mounted behind a tractor, this view showing the mechanism for picking up an entire row of seedlings from a tray, transferring the seedlings to a mechanism which eliminates gaps between seedlings, a discharge mechanism for dropping individual seedlings into a drop tube, and a planter subassembly which incorporates a plant feeder subassembly for discharging the seedlings one at time to the ground with a desired spacing between the seedlings, some parts not being illustrated. 
           [0018]      FIG. 1B  is a view similar to  FIG. 1A , but showing some of the parts not shown in  FIG. 1A   
           [0019]      FIG. 2A  is a top view of the transplanter shown in  FIG. 1A , parts being broken away to show the ground wheels. 
           [0020]      FIG. 2B  is a top view of a three row transplanter of this invention. 
           [0021]      FIG. 3A  is a view from the front of the transplanter shown in  FIG. 1A , this view showing the mechanism for reciprocating the spears up and down, and also showing a portion of the tray indexing mechanism with a portion of a tray, portions not being shown for purposes of clarity. 
           [0022]      FIG. 3B  is a detail of  FIG. 3A  further illustrating a portion of the tray indexing mechanism, two complete trays being illustrated. 
           [0023]      FIG. 3C  is a left side view along the line  3 C- 3 C in  FIG. 3B . 
           [0024]      FIG. 3D  is an enlarged side view taken generally along the line  3 D- 3 D in  FIG. 3B , the tray not being shown, the tray pressure plate being shown in its fully extended position. 
           [0025]      FIG. 3E  is a top view of the tray indexing mechanism shown in  FIG. 3B . 
           [0026]      FIG. 3F  is a sectional view taken generally along the line  3 F- 3 F in  FIG. 3B , showing a tray positioning lock engaging a tray to align the cells for proper spear alignment. 
           [0027]      FIGS. 3G and 3H  are enlarged top and side views of the tray positioning lock assembly shown in  FIGS. 3E and 3F . 
           [0028]      FIG. 3J  is a sectional view taken generally along the line  3 J- 3 J in  FIG. 3B . 
           [0029]      FIG. 4A  is a rear elevational view of the tray indexing mechanism and further showing the foliage separation spear and the foliage deflector spear in their lower positions where the tip of the foliage separation spear is positioned where it can be extended to cause separation of seedlings in adjacent trays, the spear point of the foliage deflector spear lifting seedlings that may be laying over, the tray having been engaged by the tray positioning lock shown in  FIG. 3H . 
           [0030]      FIG. 4B  is an enlarged view of a portion of  FIG. 4A . 
           [0031]      FIG. 4C  is a rear view showing the foliage spears and the pivotal seedling extraction spears partially raised. 
           [0032]      FIG. 5A  is a view similar to  FIG. 4C , but showing the foliage spears and the pivotal seedling extraction spears in a raised position, where they may be “bumped” or “jittered” to ensure all of the seedlings are in the pivotal seedling extraction spears. 
           [0033]      FIGS. 5B and 5C  are views taken generally along the line  5 B/C- 5 B/C in  FIG. 5A  showing in  FIG. 5B  the extraction bladder of the pivotal seedling extraction spears collapsed after a vacuum has been drawn on the bladder and showing in  FIG. 5C  the bladder inflated and expanded against the seedling stems. 
           [0034]      FIG. 6A  is a right side elevational view showing the pivotal seedling extraction spears in an intermediate position as they move from a raised position to a delivery position, the spear support carriage being still in the fully raised position. 
           [0035]      FIGS. 6B and 6C  are perspective views illustrating how the spring loaded side plates on the seedling extraction spears raise to cause the root-ball to assume an erect position. 
           [0036]      FIG. 6D  is a cross section through the seedling extraction spears when in their lowered position, this view being taken generally along the line  6 D- 6 D in  FIG. 6C , seedlings being omitted for purposes of clarity. 
           [0037]      FIG. 7  is a left side elevational view similar to  FIG. 6A , but showing the pivotal seedling extraction spears in their fully lowered position, and with the foliage spears moved to their lower position. 
           [0038]      FIGS. 7A and 7B  are details of a portion of  FIG. 7  showing the adjustable stops in contact with the stop abutment when the seedling extraction spears are in their lower position in  FIG. 7A  and in their upper position in  FIG. 7B . 
           [0039]      FIG. 8  shows the seedling loader group moving to the seedlings carried by the seedling extraction spears, parts being omitted. 
           [0040]      FIG. 9  shows the seedling loader group positioned over the seedlings carried by the seedling extraction spears. 
           [0041]      FIG. 9   a  is a view similar to  FIG. 9 , but showing seedlings delivered to the gap-up mechanism, a gap in the seedlings being shown. 
           [0042]      FIG. 10  is a view similar to  FIG. 9   a  but showing no gap in the seedlings after a number of seedlings have been discharged. 
           [0043]      FIG. 11  is a view of a portion of the structure shown in  FIG. 9   a , this view being taken from the left end of  FIG. 9   a , or from the front of the apparatus. 
           [0044]      FIG. 12  is a right side view of a portion of the seedling loader group. 
           [0045]      FIG. 13  is a bottom view of a portion of the structure shown in  FIG. 12 , parts being omitted for purposes of clarity. 
           [0046]      FIGS. 13A and 13B  are front elevational views showing the root-ball loaders in their open and closed positions, respectively. 
           [0047]      FIGS. 13C and 13D  are enlarged sectional views showing how a cam is operated by a cylinder assembly to force the root ball loaders from a closed position shown in  FIG. 13C  to an open position shown in  FIG. 13D . 
           [0048]      FIG. 14  is a view from the left of  FIG. 12  illustrating a pair of gates to prevent a root ball from tipping over, the gates being open in this view. 
           [0049]      FIG. 15  is a view similar to  FIG. 14 , but with the gates closed. 
           [0050]      FIG. 16  is a plan view of root ball pinchers. 
           [0051]      FIG. 16   a  is a section taken generally along the line  16   a - 16   a  in  FIG. 16 . 
           [0052]      FIG. 17  is an enlarged view of a portion of  FIG. 9  showing how a seedling is lifted up and away from the gap eliminating subassembly by the discharge mechanism, this view also illustrating the progressive movement of a seedling after it has been lifted up and away from the gap eliminating subassembly, and further showing the cut-off gate in its raised position after the seedling has been lifted up and away from the gap eliminating subassembly. 
           [0053]      FIG. 17A  is a top view of a portion of the structure shown in  FIG. 17 . 
           [0054]      FIG. 18  is a perspective view of a portion of the discharge mechanism. 
           [0055]      FIG. 19  is a view showing a plant, including a root ball, stem and leaves, being discharged from the discharge mechanism. 
           [0056]      FIG. 20  is an end view of  FIG. 19 . 
           [0057]      FIG. 21  is a side view of the planter subframe and plant feeder subassembly showing the transfer disks in a rear position adjacent planting disks which are disposed between a pair of press wheels. 
           [0058]      FIG. 22  is a view similar to  FIG. 21 , but showing how transfer disks of the plant feeder subassembly may be moved between forward and rear positions to accommodate seedlings having different stem and foliage lengths, the press wheels not being shown in this view. 
           [0059]      FIG. 23  is a sectional view of the apparatus shown in  FIG. 22 , this view being taken generally along the line  23 - 23  in  FIG. 22 . 
           [0060]      FIG. 24A  is a view similar to  FIG. 22 , but showing the transfer disks in the rear position and showing additional details. 
           [0061]      FIG. 24B  is a partial sectional view showing the double doors to the rear of a root ball kicker. 
           [0062]      FIG. 25  is an end view of a seedling inside the seedling receiver which is between the transfer disks. 
           [0063]      FIG. 26  is a view similar to  FIG. 21 , but showing the transfer disks in their forward position. 
           [0064]      FIGS. 27-30  show various transfer disks characteristics,  FIG. 27  showing where the transfer disks are engaging the root ball of the seedling,  FIG. 28  showing the air knife effective area,  FIG. 29  showing where the transfer disks are held open so they may receive individual seedlings for transfer, and  FIG. 30  showing where the air knife performs a foliage correction. 
           [0065]      FIGS. 31A-31D  show how a seedling is transferred from the seedling receiver to the planting disks. 
           [0066]      FIGS. 32-36  show various flow charts relevant to the operation of this apparatus. 
       
    
    
     DETAILED DESCRIPTION  
     In General 
       [0067]    The transplanter of this invention is indicated generally at “T” in  FIG. 1 . It may be semi-integrally mounted on the three point hitch  20 ,  22 ,  24  of a tractor  10 , only a portion of which is shown in  FIG. 1 . A box-like subframe indicated generally at  30  is in turn carried by the three point hitch. Mounted on the back of the subframe  30  is a tool bar  32  which in turn carries wheels  34 ,  36  shown only in  FIG. 2A . Each of the wheels is carried by a pivoted sub-frame (not shown) which is in turn pivotally secured to the tool bar. Each of the wheels may be moved up and down. As this design is conventional, it is not illustrated. 
         [0068]    Mounted on the sub-frame  30  is high volume air compressor indicated generally at  40  and also, but not shown, a high pressure air compressor, a 24 volt alternator, and a 24 volt battery source, the compressors and alternator being powered by the PTO shaft  42  of the tractor. The air discharged by the air high pressure compressor provides the power required by the various air motors on the transplanter, and the air from the high volume compressor is used by air knifes and to assist flow through the drop tube. 
         [0069]    The transplanter includes an operator support or platform  50 . Mounted on the operator support  50  is a horizontal transplanter subframe  52 . This in turn carries front and rear vertical subframe assemblies indicated generally at  54  and  56 , respectively. An arched subframe  58  extends from the top of the vertical subframe  54  downwardly and to the back to a location in front of the rear vertical subframe  56 . The arched subframe  58  carries many air lines and electrical controls shown generally at  60  in  FIG. 2A . In addition, control modules  62  may be mounted on the subframe  58 . A high pressure air reservoir and a low pressure air manifold are carried below the platform  50 . 
         [0070]    The transplanter consists of several major subassemblies. A first major subassembly is the tray indexing mechanism which is indicated generally at  100  and which is best illustrated in  FIGS. 3A to 3J . The subassembly for picking up an entire row of seedlings from a tray is indicated generally at  300 , and is best illustrated in  FIGS. 4A to 8 . The subassembly which eliminates gaps between seedlings is indicated generally at  500  and is best illustrated in  FIGS. 8 to 12B , and consists of a seedling loader group, continuously running gap-up belts, a cut-off gate and a gap-up root-ball pincher. There is a discharge mechanism which is indicated generally at  700 , which mechanism includes a feeder pinch disk assembly or discharge disk assembly for dropping individual seedlings to one or more drop tubes for receipt by a planter assembly. The planter assembly, which plants individual seedlings in the ground, includes a planter frame subassembly indicated generally at  800 , which frame subassembly supports furrow opening and closing mechanisms. The planter assembly further includes a plant feeder subassembly indicated generally at  1300 . 
         [0071]      FIG. 2B  illustrates a three row version, whereas  FIG. 2A  illustrates a single row version. The three row version does not differ significantly from the two row version, except that the operators support platform is larger. In addition, the tray indexing mechanism, the subassembly for picking up an entire row of seedlings from a tray, and the subassembly which eliminates gaps between seedlings, and for sending the seedlings into a drop tube are reversed in the center row unit. However the planter subassembly in the center row unit, not shown, is not reversed. 
       Tray Indexing Mechanism 
       [0072]    The tray indexing mechanism is best shown in  FIGS. 3A-3H . Initially, it should be noted that in the transplanting industry, various nurseries use various trays, the trays having differing depths, widths, lengths, and different spacings between adjacent rows of cells. Accordingly, the tray indexing mechanism, which is indicated generally at  100 , should be adjustable to accommodate trays of differing widths, etc. The indexing mechanism is carried by the vertical subframe  54  which includes a pair of vertically extending spaced apart angle iron frame members  106 ,  108 . The indexing mechanism is provided with horizontal tray holding rails  102 ,  104 . The top tray holding rail  102  is secured to the top of the frame members  106  and  108  by suitable fasteners  110 . The bottom rail  104  is adjustably secured to one of a plurality of apertures  112  in each of the frame members  106 ,  108  by suitable fasteners  114 , the bottom rail being shown in its lowermost position in  FIG. 3A . 
         [0073]    In  FIG. 3A  a large tray is indicated generally at  116 . In FIG,  3 B two large trays are shown. Each of the trays is rectangular and has spaced apart long sides  116 . 1  and spaced apart shorter sides  116 . 2 . Spaced between the sides are seedling receiving cells  116 C which are square in cross section, open at the top, and partially closed at the bottom. This tray design is conventional and well known to those skilled in the art. 
         [0074]    When the trays are positioned in the tray indexing mechanism, the sides  116 . 1  of each tray will be slidably positioned between rails  102  and  104  and may be held by their sides  116 . 1 . As can best be seen from  FIG. 3D , each of the tray holding rails  102 ,  104  is provided with a rear lip  102 . 1  or  104 . 1 , respectively, which rear lip engages the top side  116 T of the tray  116  when it is mounted between the rails as can be seen in  FIG. 3C . A pressure plate  118  will bear against the bottom  116 B of the tray  116 . If the tray is of a depth less than that shown in  FIG. 3C , the pressure plate  118  will bear against the bottom of the tray and force it into engagement with the lips  102 . 1  and  104 . 1 . The pressure plate is carried by a pair of bolts  120  (only one of which is shown) and the pressure plate is biased towards the lips  102 . 1 ,  104 . 1  by a pair of compression springs  122 . While only a single pressure plate is shown, a pair of upper and lower pressure plates may be employed. 
         [0075]    In summary, to index the tray when mounted between the rails, a clamping mechanism will engage the sides of a tray, the mechanism including a vertical cylinder assembly  124  ( FIG. 3J ) operated to cause the sides  116 . 1  of the tray to be clamped by spaced apart upper and lower rubber clamps  126 . A horizontal cylinder assembly  128  will be operated to move the clamping mechanism to the left as seen in  FIG. 3E  a distance about the size of one cell. After the tray has been indexed, the clamping mechanism will release the tray by operating the vertical cylinder assembly  128  which will be extended to release the clamps. At this time a tray positioning lock mechanism indicated generally at  130  will be operated to engage a cell to finally position the tray. 
         [0076]    The indexing mechanism further includes a pair of mounting structures  132 ,  134  ( FIG. 3B ) which are secured via fasteners  136  ( FIG. 3C ) at their upper and lower ends to the fixed rails  102 ,  104 . As best shown in  FIGS. 3B and 3C , each of the mounting structures  132 ,  134  is provided with a pair of upper and lower bushings  138 ,  140  which receive slide rods  142 ,  144 , respectively. A slidable subframe assembly indicated generally at  146  is mounted on the slide rods for sliding movement with the rods. The slidable subframe includes right and left mounting plates  148 ,  150 , respectively. The plates are suitably secured to the slide rods so that they will move with the slide rods. In addition, a pair of upper and lower spacers  152 ,  154  are placed about bolts  153 ,  155 . Each bolt is screwed into the left mounting plate  150 , the bolts being turned until the spacers  152 ,  154  are trapped between the mounting plates  148 ,  150 . This will insure that the plates  148 ,  150  will move together. The slidable subframe  146  is caused to move by the horizontal cylinder assembly  128 . To this end, the cylinder of the assembly is rigidly secured to the mounting structure  134  with the rod  156  extending thorough a suitable aperture in the structure  134 . The end of rod  156  is secured to the left mounting plate  150  in any suitable manner. When the cylinder assembly  128  is extended, the subframe assembly will be moved away from the mounting structure  134 , and when the cylinder assembly  128  is retracted, it will be moved towards the structure  134 . A pair of adjustable stops limit the movement of the rod towards the structure  134 , the stops being adjusted so that the movement of the rod from its fully extended position to its stopped position approximates the width of a cell on the tray. Each of the stops may include a threaded rod  158  which passes though a suitable threaded aperture in structure  134 , a nut  160  to hold the rod in its position of adjustment, a bumper  162  at the end of the rod, which bumper is contacted by the left mounting plate  150  when the slidable subframe assembly is moved towards the mounting structure  134 . 
         [0077]    The rubber clamps  126  are caused to clamp the tray  116  by operation of the vertical cylinder assembly  124 . To this end, each of the upper and lower rubber clamps is carried by a horizontal bar  164 , there being three spaced apart rubber bumpers on each bar, the rubber bumpers being adapted to pass through suitable elongated apertures  166  in the upper and lower fixed rails  102 ,  104 . Each of the horizontal bars  164  is carried by a pair of spaced apart arms  168  which are secured for pivotal movement to a mounting plate via pivot pins  170 , plate  148  being shown in  FIG. 3J . Each arm is provided with an inwardly extending cylinder mount  172 . The cylinder assembly includes a cylinder  174 , the anchor end  175  being secured to one of the cylinder mounts  172 , and the rod  176  being secured to the other cylinder mount. The cylinder assembly  124  is a double acting cylinder, and when retracted it will cause the rubber clamps to bear against the sides of the tray  116 , and when the cylinder is retracted, it will cause the rubber clamps  126  to move away from the sides of the tray  116 . 
         [0078]    In operation, after suitable trays have been slid between the top and bottom tray holding rails  102 ,  104 , it will be necessary to initially engage the right hand tray (as viewed in  FIG. 3B ) with the rubber clamps. As the clamps will move with the slidable subframe assembly, to move trays to the left as viewed in  FIG. 3B , it is only necessary to extend the horizontal cylinder assembly  128 , which will cause the associated trays to move to the left approximately one cell width, movement of the right hand tray to the left causing the left hand tray to move an equal distance as the trays abut one another. Once this movement has been completed, as can be sensed by sensor  178  on cylinder  128 , the cylinder will be retracted a distance about equal to one cell width. However, before retraction can take place, it is necessary to extend the vertical cylinder assembly  124  to cause the rubber clamps to move away from the sides of the associated tray(s), so that the trays will not move during retraction of the horizontal cylinder. For control purposes, the vertical cylinder is also provided with a sensor  180 . 
         [0079]    As previously noted a tray positioning lock assembly  130  is provided to engage a tray to align the cells for final positioning and for proper spear alignment, which tray positioning lock mechanism can be considered as a portion of the tray indexing mechanism. In this regard, it should be observed that the tray indexing mechanism described above may work well with a single tray, but after one tray has been fully discharged, and before the next tray starts, there is a double wall thickness which is not adjusted for in the stop assembly  158 - 162 . In addition, it is possible that cumulative indexing errors may occur. Therefore, it is essential that a final positioning apparatus be provided to insure that after every indexing movement a final and correct position is attained. 
         [0080]    The tray positioning lock assembly  130 , which is the final positioning apparatus, is supported on the top tray holding rails  102 . To this end an L-shaped mounting bracket  200  is provided, the part having a wide rectangular portion  200 . 1  ( FIG. 3G ) provided with suitable apertures for the reception of fasteners  202  ( FIG. 3E ) so that it may be secured to top rail  102 . The L-shaped bracket further includes a relatively narrow rectangular extension  200 . 2  which carries round bars  204  secured in place by set screws  206 . A C-shaped member  208  is slidably carried by the bars  204  and may be moved to various positions of adjustment. To this end, a threaded rod  210  passes through a threaded aperture in portion  200 . 2 , the threaded rod carrying spaced apart nyloc nuts  212  which bear against opposite sides of the C-shaped member. A hand knob  214  is carried by one end of the threaded rod. It should be apparent that if the threaded rod is rotated by the knob  214 , the C-shaped member will be caused to be moved from side to side. The C-shaped member carries a cylinder assembly indicated generally at  216 , which is secured to the bight portion  208 . 1  of the C-shaped member. The rod  218  of the cylinder assembly  216  carries a V-shaped tray centering plunger  220 . It should be apparent that when the rod  218  and centering plunger are extended, the V-shaped plunger will enter a cell and cause the associated tray, which has been released for sliding movement, to move laterally, if necessary, to center the tray. In order to prevent bending of the tray when this occurs, the L-shaped member carries a skid-shoe  222  which may be adjustably positioned to conform to the thickness of the tray. 
       Subassembly for Picking up a Row of Seedlings 
       [0081]    The subassembly for picking up an entire row of seedlings consists of two pairs of spears, which spears are mounted on a vertically reciprocal carriage assembly indicated generally at  302 . As can best be seen from  FIG. 3A , the carriage assembly includes vertical right and left slide rods  304  and  306 , which are secured thereto. The rods are received in upper and lower bushings  308 . The lower bushings are carried by lower bushing mounting brackets  310  which are in turn secured to the right and left frame members  106 ,  108 . The upper bushings  308  are carried by an upper cross member  312  also secured to the right and left frame members  106 ,  108 . A carriage reciprocating double acting air cylinder assembly is carried by the cross member  312 , the assembly including a cylinder  314  secured to the cross member  312 , and a downwardly extending rod  316  which passes through a suitable aperture in cross member  312 . The lower end of rod  316  is secured to a suitable bracket  318 , which is in turn carried by the principal cross plate  320  of the carriage assembly. Upper right and left bumpers  322 ,  324 , as well as lower right and left bumpers  326 ,  328  are carried by the cross plate  320  and limit the movement of the carriage. When the double acting cylinder assembly  314 ,  316  is retracted, the upper bumpers  322 ,  324  will contact the cross member  312 . Similarly, when the cylinder assembly is extended the bumpers  326 ,  328  will contact the right and left brackets  310 . 
         [0082]    Mounted on the cross plate  320  are right and left rearwardly extending plates  330  and  332 , respectively. A pivot shaft  334  is rotatably supported by the plates. An L-shaped bracket  336  is carried at the lower end of the right hand plate  330 . Fore and aft double acting air cylinders  338 ,  340 , respectively, are secured to the underside of the L-shaped bracket, and the rods  342 ,  344  of the respective cylinders extend above the bracket, each rod terminated in a clevis,  346 ,  348 , respectively. A chain  350  is secured to the two devises and passes over a sprocket  352  secured to an end of shaft  334 . It should be apparent that as the cylinders are extended and retracted they will cause the shaft to rotate. Extension and retraction of the cylinder are monitored by a sensor  354  mounted on one of the cylinders. 
         [0083]    Fixed to the cross plate  320  is a first mounting block  356 , and secured to the pivot shaft  334  is a second mounting block  358 . A first pair of spears are carried by the first mounting block for reciprocal vertical movement only, the first pair including a foliage separation spear  360  and a foliage deflector spear formed of a long bar  362  and a spear point  363 . As can best be seen from  FIGS. 5B and 5C , the foliage separation spear is generally L-shaped in cross section, except that its top point is curved towards the spear point as can be seen from  FIG. 4B , and it additionally has a tapered leading edge  360 . 1  as can best be seen from  FIGS. 7 and 8 . A pair of right and left seedling pivotal extraction spears are indicated generally at  364  and  366 , respectively. They are carried by the second mounting block  358  for reciprocal and pivotal movement as can best be seen from an inspection of  FIGS. 4A ,  4 C, and  5 A which show the spears moving up through the seedlings carried by a tray.  FIGS. 6A and 7 ,  FIG. 6A  show the initial pivotal movement of the extraction spears away from the tray of seedlings, the separation and deflector spears still being in their fully raised position.  FIG. 7  shows the extractions spears and the separation and deflector spears in their lowered position. A stop arm  367  is secured to the pivot shaft  334  and carries adjustable stops  367 A and  367 B which limit the rotational movement of the extraction spears, the stops contacting an abutment block  333  mounted on left plate  332 . 
         [0084]    In certain positions of operation the seedling extraction spears are designed to fit between the foliage engaging spears as can best be seen from  FIGS. 4B ,  5 B and  5 C. Thus, the left foliage extraction spear  366  includes a generally rectangular member  368  as shown in  FIG. 6D . The lower end is secured to the mounting block  358  carried by the pivot shaft  360 . The right hand foliage extraction spear has a C-shaped elongated member  370  which carries a bladder  372  shown in its normal position in  FIG. 6D . 
         [0085]    At the commencement of operation of the spears, they will be in the positions shown in  FIGS. 4A and 4B  as well as in the position shown in  FIG. 7 , except that the seedling extraction spears will be free of seedlings. Operation of the cylinder  338 ,  340  will cause the seedling extraction spears to pivot about the shaft  334  from the retracted position shown in  FIG. 7  until they reach the extended position where they lie between the foliage spears  360 ,  362 . After the rotational movement has been completed, they will still be in a carriage lower position shown in  FIG. 4A . At this point a vacuum will be drawn on the bladder  372  via a venture vacuum pump (not illustrated) to collapse it to the position shown in  FIG. 5B , the pump being connected to the high pressure air compressor via suitable lines and valves. The cylinder  314  will now be operated to move the carriage  302  upwardly which will cause corresponding movement of the two pairs of spears. The leading spear point  363  of foliage deflector spear will slide up along the right hand edge of the row of seedlings which are to be engaged, and force up the stems and foliage which may be leaning to the right so they may be engaged by the seedling extracting spears. At the same time the left foliage separation spear, which extends further away to the tray which carries the seedlings, will act to untangle the foliage of adjacent rows of seedlings to facilitate engagement. When both pairs of spears have initially attained their raised position shown in  FIG. 5A , they may be “bumped” or “jittered” to ensure all of the seedlings are in the pivotal seedling extraction spears. The bladder will be inflated to firmly engage the stems of the seedlings as shown in  FIG. 5C , inflation being controlled via a suitable valve interconnected with the high pressure air compressor. The seedling extraction spears will now be rotated away from the seedling trays to the position shown generally in  FIG. 6A , where the cylinder  314  will now be operated to lower the carriage and both pairs of spears, the pivot shaft rotating cylinders continuing to operate to move the seedling engaging spears to their fully lowered position shown in  FIG. 7 . In this respect, the carriage  302 , cylinder  314 , shaft  334 , and cylinders  338 ,  340  can be considered means for moving the foliage extraction spears  364 ,  366  between extended and retracted positions. Thus, the spears  364 ,  366  are moved from a position below the seedlings as shown in  FIG. 4A  to a position where the seedlings are between as shown in  FIG. 5A , the spears  364 ,  366  then being moved away from the tray as shown in  FIG. 6A  and then  FIG. 7 . 
         [0086]    Typically the root ball of the seedling will not extend to the top of the cells in the tray. Thus, when they are extracted, as the extraction spears do not extend into the cells of the tray, there would be a tenancy for the root balls to tip over, this being illustrated in  FIG. 6B . In order for the seedling loader group to properly engage the root balls, it is necessary to bring them into an erect position. This is accomplished by spring loaded side plates on the seedling extraction spears, which will move from a compressed position when in the  FIG. 5A  position where the extraction spears initially engage the stems of the seedlings, to a raised position as illustrated in  FIG. 6C  to cause the root-ball to assume an erect position. 
         [0087]    The spring loaded side plate for the right hand extraction spear  364  is indicated at  374 . The member  370  has an elongated support  376  which is suitably secured thereto by fasteners  378 . Downwardly extending dowels or rods  380  are carried by the support  376 , and a bar  382  is carried at the lower ends of the dowels. Mounted for sliding movement is an apertured side plate support  384  to which the right side plate  374  is secured. Springs  386  normally bias the support  384  and plate in an upwardly direction to raise the root balls RB to the position shown in  FIG. 6C . The left-hand seedling extraction spear  366  is also provided with a side plate  388  mounted on a side plate support  390 . The support  390  is mounted on dowels  392  carried by an L-shaped mounting plate  394 , and springs extend between a portion of the mounting plate and the side plate support to normally force the side plate to a raised position. 
       Gap Eliminating Subassembly 
       [0088]    The subassembly which eliminates gaps between seedlings is best illustrated in  FIG. 9 . The gap eliminating subassembly includes a plant transfer carriage or seedling loader group indicated generally at  500 , which group carries root ball loaders in the form of right and left opposed sheet metal structures  502 ,  504 . The seedling loader group will engage the root balls of the seedlings and move them towards and over a pair of gap-up belts  506 ,  508  which run continuously during the operation of the apparatus of this invention. When the root-balls of the seedlings are fully positioned over the gap-up belts, they will be released, and the tops of the root balls, which are in an upside-down position, will rest on the gap-up belts for movement towards a cut-off gate  510 . The cut-off gate will be operated in a suitable manner to release one seedling at a time, which seedling will be picked up by a discharge mechanism  700 , which will be described below. 
         [0089]    The vertical subframe  56  which supports the seedling loader group and the gap-up belts includes a lower weldment having a pair of spaced apart vertically extending plates  512  and an upper weldment also having a pair of spaced apart vertically extending plates  514 , which plates  512  and  514  may be adjustably secured to each other. The vertical subframe further includes upper right and left spaced apart plates  516 ,  518 , respectively. In the illustrated embodiment, each of the plates  516  and  518  are made of three pieces, which are bolted together, however, it could be made of a single piece. 
         [0090]    Extending between upper portions  516  and  518  are front and rear transverse plates  520 ,  522 . Each of the plates receive right and left slidable rods  526 ,  528 . Suitably secured to the rods are a front triangular support  530  and a rear support/manifold  532 . The mounting plate  534  for the root ball loaders  502  and  504  is interconnected to the front and rear plates  530 ,  532  for movement therewith. Carried by the mounting plate  534  are front and rear pivot plates  536 ,  538 , ( FIG. 12 ), each carrying a pair of pivot arms  540 , the sheet metal structures  502 ,  504  being secured to the arms  540 . The arms are biased towards each other by front and rear springs  542 . 
         [0091]    The root ball loaders  502 ,  504  are moved between a forward position, shown in  FIG. 9  and a rear position shown in  FIGS. 9   a  and  10  by an air cylinder assembly  544  including cylinder  545  and rod  546 . The anchor end of cylinder  545  is secured to the rear transverse plate  522 , the front end of the cylinder  545  is supported by front transverse plate  520 , the front transverse plate being apertured so that the rod  546  of  25  the cylinder may pass through. The front end of the rod is secured to the front support  530 . It should be apparent that as the cylinder assembly is extended, the root ball loaders  502 ,  504  will be moved in a forward direction, and as the cylinder is retracted the root ball loaders will be moved in a rearward direction towards the discharge mechanism  700 . 
         [0092]    The sheet metal root ball loaders are caused to open by a cam  548  ( FIG. 13 ). A rod  550  of cylinder assembly  552  carries the cam, the anchor end of cylinder  554  being secured in a suitable manner to the mounting plate  534  via nut and bolt assembly  556 . A rod extension  558  is carried by the cam  548  and passes through a suitable bushing  560  in the front pivot plate  536 . The cylinder assembly  552  is a double acting air cylinder and is suitably connected to ports in the rear support/manifold  532  by air lines, not shown. The manifold is in turn connected to separate air lines for controlling the extension and retraction of the cylinder. When the cylinder assembly  552  is extended, the cam  548  will engage cam followers  562  on cam follower arms  564  carried by the structure  502  and  504 , to cause the sheet metal structures to open as shown in  FIGS. 13   a  and  13 D. When the cylinder assembly  552  is retracted, springs  542  will cause the sheet metal structures to close and grasp any root balls between them. 
         [0093]    There is a tendency for the rear root ball to fall down towards the rear when the seedling extraction spears  364  and  366  are positioned in their lowered position shown in  FIG. 7 . Therefore, a tip-up gate assembly  566  is provided in the seedling loader group, the tip-up gate assembly being best shown in  FIGS. 9 ,  12 , and  14 - 15 . The gate assembly  566  includes front and rear mounting bars  568 ,  570  ( FIG. 12 ). Pivotally secured to the mounting bars by pivot pins  571  are gate mounting plates  572 , each of which carries a gate  574 . The pair of gates  574  are normally spring biased to their open position shown in  FIG. 14  by tension springs  576 . However, when the seedling loader group is moved to the fully extended position shown in  FIGS. 9 and 15 , the gates will be moved to their closed position when cam or ramp  578  is engaged by cam follower  580 , causing the gates to bear against the rear root ball, moving it to an upright position before it is grasped by the seedling loader group. When the seedling loader group  500  is moved from the fully extended position shown in  FIGS. 9 and 15  to the fully retracted position shown in  FIGS. 10 and 14  by operation of the air cylinder  544 , the cam followers  580  will move from the  FIG. 15  position to the open position shown in  FIG. 14 . As the rear root ball is now held by the root ball loader  502 ,  504 , it will remain in the upright position until it is released onto the gap up belts. When the seedling loader group  500  is in the fully retracted position shown in  FIG. 10 , the sheet metal structures  502 ,  504  will be opened. At this point the root balls will drop onto the gap-up belts  506  and  508 . 
         [0094]      FIG. 9   a  shows a plurality of root balls delivered to a gap-up mechanism. In this view, there is a gap between adjacent root balls. However, as the gap-up belts are continuously running, the gap between the root balls will quickly be closed as can be seen from an inspection of  FIG. 10 , the closure being achieved as the root balls are forced against each other, the rearmost root ball being held by cut-off gate  510 . 
         [0095]    Intermediate portions of the gap-up belts  506 ,  508  are supported by longitudinally extending high density polypropylene strips  600  carried by longitudinally extending bars  602  which are in turn carried by supports  604 . The supports  604  are secured to right and left plates  516 ,  518 . 
         [0096]    The gap-up belts are driven continuously during the operation of the machine by a DC motor  606  suitably mounted on the upper plates  516 ,  518 . A cogged drive sheave  608  is mounted on the output shaft of the motor. A cogged belt  610  passes over the drive sheave  608  and driven cogged sheaves  612  and  614 , sheave  614  being secured to cross shaft  615 . An idler sheave  616  maintains tension in the belt. The sheave  612  is mounted on a cross shaft  618  suitably journalled in right and left upper plates  516  and  518 , the cross shaft in turn carrying right and left drive sheaves  620  and  622  over which right and left drive belts  624 ,  626  are passed, these belts in turn driving the right and left gap-up belts  506  and  508 . 
         [0097]    The longitudinally supporting bars  602  also support the front and rear sheaves over which the gap up belts pass. To this end front and rear offset bar extensions  628  are provided, each of which extensions is of a L-shape. A side of the L-shaped bracket  628  is bolted as at  630  to an end portion of the bar  602 , as indicated in  FIG. 11 . A rotatable shaft  632  passes though a portion of the L-shaped extension beyond the bar  602 . Mounted on the end of the shaft are driven and drive sheaves  634 ,  638 , the driven sheave being driven from drive sheave  620  or  622  via a belt  624  or  626 , and the drive sheaves  636  in turn driving the gap-up belts  506  and  508 . 
         [0098]    The cut-off gate  510  has the function of stopping the lead root ball so that next trailing root ball will press against the leading root ball, thus eliminating any gaps. In addition, the cut-off gate will be operated to release root balls at precise intervals to insure that proper spacing may be achieved. In the illustrated embodiment the single cut-off gate on the feeder head is operated by a pair of double acting air cylinders  680  which are supported for adjustable longitudinal fore and aft movement by a carriage  682  supported for adjustable movement on a pair of longitudinally extending rods  684  which are in turn supported by plates  686 . The plates are in turn supported on the right and left upper plates  516 ,  518  in any suitable manner. A screw mechanism including a screw  688  and a knurled wheel  690  may be used to adjust the position of the gate to accommodate root balls of differing diameters. Thus, differing nurseries use plant trays having differing sized cells. 
       Discharge Mechanism 
       [0099]    The principal components of the discharge mechanism are root ball pinchers, indicated generally at  702  ( FIG. 16 ), which act in concert with the gate  510 , and a feeder pinch disk assembly or discharge disk assembly  704 . Right and left root ball pinchers  702  are mounted on the upper edge of the right and left upper plates  516  and  518 , respectively. To this end, each of the root ball pinchers includes a L-shaped bracket  706  secured to a bar  708  secured to an upper end of the side plate  516  or  518 . The cylinder  710  of a double acting air cylinder assembly is secured to the L-shaped bracket, the rod  712  passing through, the root ball pinchers  702  being secured to the rod. A guide rod  714  also extends from the L-shaped bracket. Each root ball pincher includes a flared pressure plate  716  mounted on a block  718 . The block  718  is secured to the rod  712 , and is provided with a suitable slot  720  or aperture for sliding receipt of the guide rod  714 . Simultaneous actuation of the cylinder assemblies  710 ,  712  will cause opposed root ball pinchers in the form of the pressure plates  716  to either move towards each other to pinch and hold the root balls from further movement, or to release the root balls so that they can be advanced. The pressure plates are flared to a more open position towards the spears, so that as the root balls are advanced towards the discharge disk assembly they will not catch upon the ends of the plates, but will easily slide in. 
         [0100]    The discharge disk assembly  704  includes right and left flexible high density polyethylene plastic disks  724 ,  726  which are suitably mounted for continuous rotation with driven shaft  615  ( FIG. 18A ), the shaft being driven by cogged belt  610  which passes over cogged sheave  614 . (While the disks may be made of polypropylene, other suitable materials may be employed.) The shaft  615  is journalled in right and left bearings  728 ,  730  carried by right and left side plates  516 ,  518 , respectively. A mounting block  732  is secured to shaft  615  for rotation therewith, the block being located midway between the side plates. The disks  724  and  726  are suitably secured to the mounting block by conventional fasteners. 
         [0101]    Means are provided to shape the disks as they are rotated in a clockwise direction as viewed in  FIG. 9 . Thus, the disks are flexible and can move from side to side, and when forced towards each other they have the ability to grasp a root ball when the gate  510  is moved up to release a single seedling, the others being held by the root ball pinchers. In order for the disks to be able to engage and transport seedlings, they are forced to together by three opposed pairs of rollers  750 ,  752 , and  754 , respectively. To this end each pair of rollers is carried by suitable leaf springs  756  which are in turn carried by suitable mounts  758  secured to the side plates  516 ,  518 . 
         [0102]    A drop tube assembly including a funnel like structure  770  is suitably mounted below the disks  724 ,  726  for the receipt of seedlings, the drop tube assembly terminating in a drop tube  780 . In order to release the seedlings, and to insure that they do not stick to the disks, a disk release member  772  extends between the disks  724 ,  726  as can be seen from  FIGS. 18A ,  19  and  20 . As the disks are rotated in a clockwise direction as viewed in  FIG. 19 , the rollers and leaf springs will force the disks together to cause them to grasp and raise a seedling away from the gap-up belts at the area of the gate, and to transport them to a drop zone where they are caused to drop by gravity as the disks are forced apart by the disk release member  772 . In addition, a flow of air directed by air jet  774 , will facilitate the discharge. A second flow of air from air knife  776 , which is connected to manifold  778 , will prevent leaves from adhering to the rear side of the funnel  770 . 
       Row Unit Planter Frame Subassembly 
       [0103]    The row unit planter frame subassembly  800 , best shown in  FIGS. 21 and 22 , is adapted to be secured to the tool bar  32  shown in  FIG. 1 . The subassembly includes a mounting weldment  802  which may be secured to the tool bar in any conventional manner. Upper and lower parallel links  804  and  806  are pivotally secured to the weldment by front upper and lower bushing assemblies  808  and  810 . The rear ends of the upper and lower links are pivotally secured to a further weldment indicated generally at  812  by upper and lower rear bushing assemblies  813  and  814 . The weldment  812  includes right and left vertically extending side bars  815  ( FIG. 23) and 816 , an upper transverse plate  817  and a lower angle iron (not illustrated), the parts being welded together. Welded to the upper and lower ends of side bars  815  and  816  are right and left horizontal rearwardly extending upper and lower bars  818  and  820 , respectively. In addition a cylinder  807  is mounted between the weldment  802  and the weldment  812  for the purpose of applying either a raising or a lowering force to the weldment  812 . 
         [0104]    A soil conditioning unit indicated generally at  821  is pivotally secured to the lower end of weldment  812 . In the illustrated embodiment the soil conditioner unit includes a pair of arms  822  which are carried by the lower ends of side bars  815 ,  816  by pivots  824 . The forward ends of the arms carry a soil conditioner, such as for example a soil conditioning wheel  826 . The height of the soil conditioning unit can be adjusted by an screw mechanism indicated generally at  828 , the details of which should be apparent from an inspection of the drawings. 
         [0105]    A furrow opener  830  is secured to the weldment  812  by a vertical bar  832  which is in turn secured to a transverse plate  834  and a bracing plate  836 , these parts being welded together. The furrow opener is of a generally V shaped construction, the apex of the V being to the forward side, and the spaced apart sides of the V being flared to the upper side. The furrow opener may be provided with various ports  838  for the introduction of water into the soil during planting. Adjustably secured to the furrow opener is a skid plate  840  for flattening the soil immediately before the seedlings are introduced into the soil. 
         [0106]    The planter subframe may be split into two parts, a forward subframe indicated generally at  1100  and a rear subframe indicated generally at  1102 . To this end upper and lower right and left fore and aft extending frame members  818  and  820  are connected at their forward ends to the right and left side bars  815  and  816 , respectively. At the rear ends each of the lower frame members  820  are provided with upwardly extending C-shaped cut-outs  1108 . The rear subframe  1102  consists essentially of right and left mounting subassemblies including right and left side plates  1109  and  1110 , respectively and right and left vertically extending mounting bars  1111  and  1112 , which bars are carried at their lower ends by a transverse pivot shaft  1113  ( FIG. 22 ) which is received in the upwardly extending C-shaped cut-outs  1108 . Each of the bars  1111  and  1112  carries a cylindrical rod  1114  which is received in C-shaped cutout  1116  in the upper frame member  818 . 
         [0107]    A C-shaped bracket  846  is secured to the trailing ends of the side plates  1109 ,  1110 , which bracket supports a press wheel supporting weldment which is secured thereto by suitable bolts  849 . The weldment includes a vertical plate  850 , rearwardly extending plate  851 , and reinforcing gusset  852 . Welded to the lower side edges of the plate  851  and to the sides of vertical plate  850  are right and left longitudinally extending press wheel mounting brackets  854  and  855 , respectively which are suitably angled to the vertical. Right and left press wheels  856  and  857  are carried by the brackets  854 ,  855 , respectively by suitable shaft assemblies  858 , the details of which are not illustrated. Mounted on the brackets  854 - 855  is a press wheel scraper assembly, which includes right and left mounting tubes  860 ,  861  suitably secured to the inner sides of the brackets, the tubes carrying at the rear ends a transverse tube  862  provided with suitable press wheel scrapers  863 . 
         [0108]    The planter subframe assembly further includes right and left knife coulters, only the left coulter  868  being illustrated. These coulters are secured to the horizontal rearwardly extending bars, one of which is shown at  820 . To this end, gusseted L-shaped brackets  871  are provided, each having elongated horizontal slots through which suitable bolts pass, the slots permitting adjustment of the brackets in a fore and aft direction. Disposed below each of the brackets is a horizontal slotted bar  872  provided with an elongated slot (not shown) through which are passed suitable bolts for adjustably securing the bars in place. The horizontal bars each carry mounting brackets  874  through which pass cylindrical shafts  876  which carry at their lower ends the knife coulters. While knife coulters are illustrated it should be apparent that other forms of coulters may be employed, for example disk coulters. 
       Plant Feeder Subassembly 
       [0109]    The plant feeder subassembly  1300  of this invention is mounted immediately below the drop tube  780  as can best be seen from  FIGS. 1B and 24 . The planter feeder includes as its principal components right and left forward transfer disks  1302  and  1303 , respectively, and right and left rear planting disks  1304  and  1305 , respectively. Each of these disks is of a construction similar to the disks  724 ,  726 , however the forward transfer disks are ½ the diameter of the rear planting disks. To this end both sets of disks are driven in such a manner that they have the same peripheral speed. 
         [0110]    The drive for the disks includes a motor  1308  mounted on the right and left side plates  1109  and  1110 , which motor drives a cross shaft  1310  carried by suitable bushings on the side plates, the motor driving the shaft through a suitable chain (not shown) and sprocket  1309 . A pair of drive sprockets  1312  and  1322  are mounted on the shaft for rotation therewith. Sprocket  1312  has a suitable chain  1316  disposed over it, which chain is also disposed over another sprocket  1318  carried by a cross shaft  1320  carried by suitable bushings mounted on the right and left side plates  1109  and  1110 . Mounted on the cross shaft for rotation with the shaft is a planting pinch disk assembly including left and right rear planting disks  1304  and  1305 . The sprocket  1322  drives a gear  1324  through a further chain  1326 . The gear  1324  is carried by extensions of the side plates  1109  and  1110  of the rear subframe  1102  and can be moved away from the forward subframe  1100 . When the rear subframe is in its operational position shown in the various figures, it will engage a further gear  1328 . This gear will in turn cause the left and right transfer disks  1302  and  1303  to be rotated. To this end, a chain  1330  drives a sprocket  1332  on the shaft which carries the disks  1302  and  1303 , causing the disks to be rotated. The chain also passes over idler sprockets  1334  and  1336  carried by a pivoted beam  1338 . By properly dimensioning the various sprockets, the peripheral speed of the disks  1302  and  1303  can be the same as the peripheral speed of the planting disks  1304  and  1305  to facilitate the handoff of seedlings from the transfer disks to the planting disks. 
         [0111]    As can be seen from  FIG. 22 , the seedling disks can be moved between forward or rear positions through various intermediate positions, not shown. Thus when the seedlings are short, the transfer disks should be in the position shown in  FIG. 24A , but when the seedlings have a greater height, the disks should be in a forward position as shown in  FIG. 26 . To this end the transfer disks are supported on a slidable subassembly  1340  which moves on an upper and two lower slide shafts  1342 . For and aft movement is caused by a screw servomotor  1344  which may be controlled by the operator. Mounted on the subassembly  1340  is a V-shaped seedling receiver  1346  which extends between the transfer disks  1302 ,  1303 . A double door  1347  is mounted to the rear of the seedling receiver and above the transfer disks, the door preventing the root ball, stem, and foliage from tipping to the rear. When desired, a kicker  1348  will be extended by cylinder assembly  1350  to move the seedlings to the rear where the root ball is caught by the transfer disks  1302 ,  1303  which have the same peripheral speed as the planting disks  1304 ,  1305 . When the kicker  1348  is operated, a double acting cylinder assembly  1351  will cause the double doors  1347  to be opened. After the root ball had been kicked out, and the kicker retracted, the double doors will be shut again by the cylinder assembly  1351 . Extending rearwardly from the slidable subassembly  1340  are a pair of sheet metal sidewalls, one of which is illustrated at  1352  in  FIG. 24A . These sidewalls each carry an air knife  1354  for the purpose of extending the stems and leaves at the time of transfer from the transfer disks to the planting disks. 
       Operation 
       [0112]    The tray indexing mechanism will properly position a tray so that the subassembly  300  for picking up an entire row of seedlings from a tray can transfer those seedlings to the subassembly  500  for eliminating gaps between seedlings. The discharge mechanism  700  includes a feeder pinch disk assembly  724 ,  726 , will pick up and drop individual seedlings to a drop tube  780  for receipt by a planter assembly. With reference now to  FIG. 25  and  FIGS. 31A-31D , the seedling will be dropped into the V-shaped seedling receiver  1346 . When desired, as shown in  FIG. 31B , the kicker  1348  will be extended by cylinder assembly  1350  to move the seedling to the rear where the root ball is caught by the transfer disks  1302 ,  1303  which have the same peripheral speed as the planting disks  1304 ,  1305 . As the seedling carried by the transfer disks moves in a clockwise direction as viewed in these figures, the opposed air knifes acting in the foliage stick correction area shown in  FIGS. 30 and 31C , will cause the foliage and stem to be extended so that the seedling can be effectively engaged by the planting disks and then moved in a counter-clockwise direction. When the root ball of the seedling is in the proper position in the furrow, the press wheels will cause it to be held by the ground. In operation, about 2 seedlings will be serially planted every second by each row unit of this transplanter. 
       Controls 
       [0113]      FIGS. 32-36  show various flow charts relevant to the operation of this apparatus. The movement of the spears is controlled in part by the reload execution loop set forth in  FIG. 32 . This control sequence will be triggered from a laser sensor receiver  1000  best shown in  FIG. 16 . This optical sensor monitor will be monitored as shown in  FIG. 32 . When the monitor receives a continuous signal from the laser emitter  1002 , indicating the absence of a root ball on the gap-up belts, the plant transfer carriage or seedling loader group will be moved from the extended position shown in  FIG. 9  to the retracted position shown in  FIG. 9   a . The seedlings will be released, and the spears will be operated as set forth in  FIG. 32 . The laser emitter and laser sensor are mounted on brackets  1004 ,  1006 , respectively, which are mounted in turn on the right and left plates  516 ,  518 . 
         [0114]    The flow chart of  FIG. 33  sets forth the process for indexing the trays. This process will not be initiated until it is called to operate from the reload execution loop set forth in  FIG. 32 . 
         [0115]    The flow chart of  FIG. 34  sets forth the controls for the gate  510  which releases a single seedling at a time from the gap-up mechanism. The input trigger is responsive to an input signal received from the wheel encoder processor illustrated in  FIG. 36 , the gate  510  being operated in the same frequency as the gate  942 . Thus, as shown in  FIG. 35 , the operation of the cut-off gate  680  is responsive to a PLC (or the equivalent) trigger input received from the wheel encoder processor, and after a finite delay, the gate cylinder  944  will be operated. The wheel encoder processor is responsive to a signal generated from a wheel encoder carried by a sensing wheel (not illustrated) which generates a distance signal as a function of the distance traveled by the transplanter. 
         [0116]    While a preferred form of this invention has been described above and shown in the accompanying drawings, it should be understood that applicant does not intend to be limited to the particular details described above and illustrated in the accompanying drawings, but intends to be limited only to the scope of the invention as defined by the following claims. In this regard, the term “means for” as used in the claims is intended to include not only the designs illustrated in the drawings of this application and the equivalent designs discussed in the text, but it is also intended to cover other equivalents now known to those skilled in the art, or those equivalents which may become known to those skilled in the art in the future.