the assembly ( a ) according to the figures is comprised of a support beam ( 1 ) which supports a vertical strut ( 2 ) and which is rigidly attached to a transverse beam ( 3 ) which forms part of a cultivator / air seeder ( not shown ). the strut ( 2 ) supports an arm ( 4 ) which includes tubular sleeve ( 5 ). the coulter ( 6 ) is mounted on a shaft ( 7 ). the coulter ( 6 ) rotates on the shaft ( 7 ) by means of a conventional hub / bearing assembly ( not shown ). the arm ( 4 ) is preferably permanently affixed to the strut ( 2 ) by welding or other suitable means . the strut ( 2 ) is held in place by sleeve ( 12 ) which is welded to lever ( 14 ). the sleeve ( 12 ) permits rotation of the strut which facilitates directional changes by the cultivator / air seeder in operation . vertical movement of the strut ( 2 ) within the sleeve ( 12 ) is restricted by collars ( 16 ) and set screws ( 18 ) which releasably attach to the strut ( 2 ) on either side of the sleeve ( 12 ). the lever arm ( 14 ) is attached to a torsion tube ( 20 ) comprising a torsion rod ( 22 ). the lever arm ( 14 ) defines a circular opening through which one end of a torsion rod ( 20 ) is inserted . the torsion rod ( 22 ) is rigidly attached to the lever arm by a bolt ( 24 ) which passes through the lever arm ( 14 ) and the torsion rod ( 22 ). the bolt ( 24 ) is held in place by a conventional nut ( 26 ). the torsion tube ( 20 ) is preferably a rubber - filled tube of the variety exemplified by commercially available flexride ™ torsion tubes manufactured by u . c . f . america inc . of pennsacken , n . j . as shown in fig4 the torsion tube comprises a casing ( 30 ) filled with rubber ( 32 ) which encases the torsion rod ( 22 ). the torsion rod ( 22 ) defines projections ( 34 ) which ensure that the torsion rod ( 22 ) does not twist within the rubber ( 32 ). the square cross - sectional shape of the casing ( 30 ) ensures that the rubber ( 32 ) does not twist within the casing ( 30 ). the torsion tube ( 20 ) may assume many different configurations . an alternative commercially available embodiment is shown in fig5 . this example is manufactured by henschen industries of jackson centre , ohio and is a lighter duty torsion tube ( 20 ) than that illustrated in fig4 . the rubber ( 32 ) permits the torsion rod ( 22 ) to rotate slightly within the torsion tube ( 20 ) but resists such rotational movement and urges the torsion rod ( 22 ) to its resting position . the torsion tube ( 20 ) is securely affixed to the support beam ( 1 ) by any suitable means . as shown in the figures , the torsion tube may be held by u - shaped mounting bolts ( 40 ) and a mounting plate ( 42 ) which is welded to the support beam and reinforced by a gusset ( 44 ). the support beam ( 1 ) may include means to secure itself to the transverse beam ( 3 ) of the implement ( not shown ). the means shown in the preferred embodiment include a l - shaped mounting bracket ( 46 ) welded to the support beam ( 1 ) and reinforced by gussets ( 48 ). the mounting bracket ( 46 ) cooperates with an l - shaped bolt ( 48 ) which secures the support beam ( 1 ) to the transverse beam ( 3 ). the depth to which the coulter ( 6 ) opens the ground ( b ) may readily be adjusted by adjusting the position of the collars ( 16 ) on the strut ( 2 ). the downward force imparted on the coulter ( 6 ) by the assembly ( a ) may be varied by pre - loading or unloading the torsion tube ( 20 ). this may be accomplished by adjusting the angle of the lever arm ( 14 ) relative to the torsion rod ( 22 ). as may readily be appreciated by those skilled in the art , angling the lever arm ( 14 ) downwards may increase the downward force imparted by the torsion tube ( 20 ) as it reacts to upward movement of the coulter ( 6 ). conversely , angling the lever arm ( 14 ) upwards may decrease the downward force . as may readily be appreciated , the present invention may be utilized with tubes ( not shown ) configured and positioned to deliver seed or fertilizer into the soil displaced by the coulter ( 6 ). such tube delivery assemblies are well known in the art . as will be apparent to those skilled in the art , various modifications , adaptations and variations of the foregoing specific disclosure can be made without departing from the teachings of the present invention . by way of example , persons skilled in the art may readily conceive and implement modifications or substitutions to the torsion means disclosed herein ( the rubber - filled torsion tubes described above ). a true torsion rod with one end affixed to the support beam and the other end affixed to the lever arm may provide the necessary biasing force . other deformable elastic materials other than rubber may be suitable for use in the disclosed torsion tubes . furthermore , the specific means disclosed to connect the components of the present invention to each other and to the transverse beam are not meant to be limiting . any suitable means of attachment or connection is intended to be within the scope of the appended claims .