the drawing figures illustrate preferred planter 10 in accordance with the present invention . referring to fig1 planter 10 includes tool bar 12 , drive wheels 14 and 16 coupled with and supporting tool bar 12 , drive mechanism 18 and a plurality of planting units 20 a , 20 b , 22 a , 22 b , 24 a , 24 b , 26 a and 26 b arranged in pairs 20 , 22 , 24 , 26 . tool bar 12 , drive wheels 14 , 16 and drive mechanism 18 are conventional components such as those available on the monosem planter available from ati , inc . of lenexa , kans . pairs 20 - 26 are substantially identical except for their relative positions along tool bar 12 . referring to pair 20 , planting unit 20 a includes a furrow opener including a pair of opener discs 28 seed hopper 30 , metering assembly 32 , a depth gauge wheel assembly including inboard depth gauge wheel 34 and outboard depth gauge wheel 36 , and a furrow closer including closer wheels 38 . in the usual manner , the planting unit 20 a further includes a seed tube 39 that extends downwardly from the metering assembly 32 and between the discs 28 so that the lower outlet end 40 is received in the furrow ( see fig3 and 5 ). in this regard , the seed tube 39 serves to deposit seed metered by the assembly 32 into the furrow . as best viewed in fig5 inboard depth gauge wheel 34 is narrower than outboard wheel 36 by about half the width thereof . except for this difference , planting unit 20 a is otherwise conventional such as the monosem planting unit available from ati , inc . mounting structure 42 includes spacer 44 having extender 46 and cross bar 48 . u - bolts 50 couple extender 46 with tool bar 12 and u - bolts 52 couple mounting face 54 of planter 20 a with cross bar 48 . spacer 44 is configured to space planting unit 20 a about six inches from tool bar 12 . this places planting unit 20 a in a staggered relationship relative to planting unit 20 b with portions thereof overlapping as best viewed in fig1 and 5 . referring to fig3 drive mechanism 18 includes conventional drive shaft 56 . mounting structure 42 includes power transfer assembly 58 for transferring mechanical power from drive shaft 56 to planting unit 20 a to operate metering assembly 32 , needed because of the spacing from tool bar 12 . power transfer assembly 58 includes drive sprocket 60 coupled with drive shaft 56 , driven sprocket 62 coupled with power shaft 63 of planting unit 20 a , chain 64 intercoupling sprockets 60 , 62 and idler sprocket 66 engaged with chain 64 to maintain the tension thereof . planting unit 20 b includes mounting face 68 mounted to tool bar 12 with no spacer therebetween . unit 20 b is otherwise the same as planting unit 20 a except for the orientation of seed hopper 72 . referring to fig2 seed hopper 72 is turned on its mounting ( compared to hopper 30 of unit 20 a ) so that it extends substantially to one side of the centerline of planting unit 20 b . planting unit 20 b also includes a narrow inboard depth gauge wheel 74 and outboard depth gauge wheel 76 . referring to fig1 and 5 , planting units 20 a , b are positioned on centers of about nine inches in the preferred embodiment . with this arrangement , units 20 a , b plant twin rows of seeds 78 and 80 also spaced apart about nine inches as are the resulting rows of crops . this is critical because conventional harvesters cannot adequately handle a crop row with a width greater than ten inches . with a spacing of less than about ten inches , the crops from rows 78 , 80 simulate a single row to a conventional harvesting machine . the planting units in the other pairs 22 - 26 are also on nine inch centers , but the pairs themselves are spaced as needed for the harvesting machine that will be used to harvest the crop . in the preferred embodiment , pairs 20 - 26 are spaced at 30 inches but spacings of 36 , 38 and 40 inches are also common . as best viewed in fig2 the orientation of seed hopper 72 to the right of the centerline of planting unit 20 b enables the close spacing between units 20 a and 20 b . this close spacing is further enabled by the narrow width of inboard depth gauge wheels 34 and 74 as shown in fig5 and by the staggered relationship between units 20 a and 20 b . as further illustrated by fig5 and the other drawing figures , planting units 20 a , b also overlap . in this relationship , the forward portion of inboard depth gauge wheel 34 is adjacent the rearward portion of inboard depth gauge wheel 74 . in this relationship , wheels 34 and 74 move in opposite directions where they overlap as planter 10 moves along the ground . this prevents dirt clods , rocks and crop residue from lodging between wheels 34 and 74 , which might otherwise be a problem if units 20 a , b were not staggered . in the use of planter 10 , metering assemblies 32 of each planting unit 20 a - 26 b are adjusted as needed for the desired seed spacing . also , the metering assemblies and mounting structures are adjusted , as needed , so that the seeds planted in each row pair are also staggered as illustrated in fig5 . this maximizes the spacing between the seeds in the twin rows for maximum yield . for a conventional planter , the normal seed spacing might be 8 seeds per foot . with the present invention , the metering assemblies can be adjusted so that each places about 6 seeds per foot , for example . for the double row planted by each pair of planting units , this results in 12 seeds per foot , which is a 50 % increase in the amount of seed planted . it has been found that this can result in a yield increase of about 25 % which substantially offsets the additional cost of seed and increases the overall profit on a given plot . as those skilled in the art will appreciate , the present invention encompasses many variations in the preferred embodiment described herein . having described this embodiment , the following is claimed as new and desired to be secured by letters patent :
a twin row planter includes planting units arranged in pairs . each pair is configured and positioned for planting two rows of seeds less than about ten inches apart to produce two rows of crops in order to increase the yield of the plot . with this spacing , the rows in each pair are close enough to simulate a single row enabling the use of a conventional cultivator , sprayer or harvesting machine .