the device of the present invention is shown generally at 10 in fig1 mounted upon a tool bar 11 behind a propelling vehicle such as a tractor which draws the tool bar forwardly in a direction transverse to the longitudinal direction of the tool bar 11 may be used in conjunction and during the cultivation operation , or may be used in a separate operation independent of the cultivation or other row crop operation . as shown in fig1 a pair of exemplary cultivator units 12 and 13 are mounted on the tool bar 11 on either side of the tillage unit 10 . each of the cultivator units 12 and 13 carries a sweep blade 14 on a lower end of a vertical shank 15 . the shank 15 is movable vertically with respect to the tool bar 11 upon upper and lower parallel arm linkages 16 , 17 which are pivotally connected at their forward ends to vertical bars 18 which form part of a rectangular front frame . this front frame is attached to the tool bar 11 by means of u - bolts 19 . the link arms 16 , 17 and 18 form with the upper part of the shank 15 a parallelogram assembly enabling vertical movement of the shank 15 and the sweep blade 14 . the specific form of cultivator forms no part of the present invention since the inventive subject matter could be used with various other cultivators of similar operational capacity or utility . in the exemplary cultivator illustrated , the shak 15 is gauged vertically by a pair of gauge wheels 20 which are carried on a frame 21 and a height adjustment arm 22 which connect together to form a triangle . the gauge wheel 20 follows the contour of local ground between crop rows , carrying the sweep blades 14 therebehind in a predetermined depth relation to the surface of the ground upon which the wheels 20 are guided . in accordance with the invention , the tillage device 10 is mounted to the tool bar 11 by means of u - bolts 30 which are attached to a first , forward frame member 31 of the device 10 arranged vertically behind the tool bar 11 . the forward frame member 31 carries upper and lower pivot pins 32 , 33 which respectively connect dual upper and lower arms 34 , 35 thereto . each of arms 34 , 35 comprise a pair of bars which are rigidly connected together to form a beam which is resistant to twisting under side loads applied to the bottom of the tillage unit . rear ends of the links or arms 34 , 35 are pivotally attached at pivot pins 36 , 37 as shown in fig3 to a second , rear frame member 38 which is arranged parallel to the first frame member 31 . the forward and rear frame members 31 , 38 and the upper and lower links 34 , 35 thus form a parallelogram arrangement much like that employed on the cultivators 12 , 13 enabling substantially vertical movement of the second frame member 38 with respect to the tool bar 11 . a tension spring 39 is connected between an upper part of the rear frame member 38 and a forward portion of the lower link arm 35 to provide a downward force upon the rear frame member 38 to avoid bouncing or lifting thereof . the tension of the spring 39 is adjustable by means of a pin 40 which is extended through any link of a chain 41 connected to the spring 39 . the pre - tension force applied to the spring 39 depends on the length of the chain 41 withdrawn from a flat bracket 42 attached to the rear side of the rear frame member 38 . a horizontally - positioned t - shaped frame 50 is affixed rigidly to the bottom of the second , rear frame member 38 by bolts as shown in fig3 extending between a base 51 integrally attached to the frame member 38 and a triangular , horizontal flange 52 of the t - bar frame 50 . the t - bar frame 50 comprises a longitudinal bar 53 and a head portion 54 attached thereto , braced by the flange 52 and extending transversely to the direction of motion of the unit 10 . since the t - bar frame 50 is affixed perpendicularly to the rear frame member 38 , it is maintained in a horizontal position despite up and down movements of the frame 38 upon the parallelogram linkage . as best shown in side view in fig3 the cross bar 54 of the t - frame 50 is formed by a piece of angle iron having a horizontal portion 55 and a vertical portion 56 . both portions of the cross bar 54 extend laterally of the parallelogram linkage of the device 10 to straddle a crop row , as shown in fig2 . carried upon the cross bar 54 laterally outwardly from the base bar 53 are a pair of gauge wheel yoke brackets 60 . these brackets are affixed to the frame 50 at the upper portion 55 of the cross bar 54 . the brackets 60 are laterally adjustable along the horizontal portion 55 upon bolts 61 connecting a mounting portion 62 of the wheel brackets 60 to the upper portion of the cross bar 54 . each pair of wheel yoke brackets extends downwardly and forwardly from the frame 50 to either side of a guage wheel 63 and to an axle 64 upon which the wheel 63 is rotatable . the wheels 63 are broad in width to have a substantial bearing area upon the ground , thereby to maintain the horizontal frame 50 in a gauged relation to a varying local crop row shoulder contour 65 . mounted upon the vertical flange 56 of the cross bar 54 of the t - frame 50 are a pair of clamp members 70 , each of which is adapted to receive in adjustable vertical relation thereto a disc blade shaft member 71 . as shown in fig1 and 2 , each clamp member 70 is affixed to the vertical portion 56 of the cross bar 54 by a pair of bolts 72 which engage through a rectangular aperture 73 extending laterally on the vertical portion 56 . tightening of the bolts 72 clamps the shaft 71 in any desired vertical , laterally - spaced apart , and angular relation to the frame 50 . disc blades 75 which in this disclosure are rotatable are mounted on the shafts 71 near lower ends thereof and transversely to the shafts 71 upon bearings to be freely rotatable as the tillage unit 10 is traversed along the ground surface 65 . the disc blades 75 have a concave side , a convex side , and a sharp edge therebetween to cut through soil and plants fibers . the concave shape casts sweepings sidewardly as shown in fig4 during forward motion of the unit 10 . since the disc blade edges are thin , the blades 75 provide substantially no ground support function but rather will slice through the ground to a depth determined by the vertical adjustment of the shaft 71 with respect to the frame 50 , which is gauged above the ground surface 65 by the wheels 63 . upon the rear of the t - frame 50 , behind the rear frame member 38 , is affixed a mounting bracket 80 having left and right rod mounting brackets 81 , 82 for receiving rods 83 , 84 which extend horizontally therefrom to either side of the frame member 38 . each of the rods 83 , 84 carries on an outer end a second mounting bracket 85 which carries transversely to the horizontal rods a nozzle carrier rod 86 . the carrier rods 86 each have a swivel clamp 87 at an expanded distal end which is engageable with a spray nozzle assembly 88 . each spray nozzle 88 is connected through a hose 89 to a source ( not shown ) of a fertilizer , weed treatment , or pest control chemical and carried either on the tractor or upon the tool bar 11 . each spray nozzle 88 is pivotable with respect to the axis of the pivot point 87 , may be swiveled and raised with the rod 86 , and may be pivoted about the rod 83 or 84 in the mounting bracket attachments 81 , 82 . where desired , more than one pair of spray nozzles 88 may be employed from the bracket 80 to provide simultaneous fertilization and weed or pest control as may be desired . in some cases only one of the spray nozzles 88 may need to be employed , as where only light crop treatment is required . since the spray nozzles 88 are carried by the frame 50 , they are gauged to local crop row contours for efficient application of chemicals thereto . in operation , the tillage assembly 10 will be mounted upon the tool bar 11 between two cultivator units 12 , 13 . the sweeps 14 of the cultivator units 12 , 13 , may be spaced apart laterally to cultivate soil in portions 90 shown in fig4 between crop rows 91 which are planted on the row or drill areas 65 . the blades 14 loosen soil and uproot weeds growing in the inter - row areas 90 , allowing penetration of rain water and air to roots of the plants growing in the rows 91 . as shown in fig4 the sweeps 14 are preceded and gauged to ground contours in the areas 90 by the gauge wheels 20 mounted to the horizontal frames 21 of the units 12 , 13 . the tillage assembly 10 is mounted to the tool bar 11 midway between the cultivator units 12 , 13 , with the gauge wheels 63 and disc blades 75 and spray nozzles 88 straddling one of the crop rows 91 between the sweeps 14 , 14 . the gauge wheels 63 will ride along shoulders of the crop row or drill 65 , with the disc blades 75 adjusted with the vertical shanks 71 thereof at the clamps 70 to sweep along the shoulder areas 92 at the intersections between the rows 65 and the inter - row areas 90 , sweeping the shoulders clean of weeds 93 growing thereon and directing the weeds into the area swept by the cultivator blades 14 . whenever necessary , the vertical shafts 71 carrying the disc blades 75 may be turned around upon their vertical shafts 71 through almost 180 ° so that the concave sides of the disc blades 75 are facing the crop row 91 to provide a &# 34 ; dirting &# 34 ; action to move soil onto the crop row 65 to cover low weeds and to raise the surface of the soil . since the disc blade clamps 70 and the nozzle mounting bracket 80 are both accessible from the rear of the unit 10 , such adjustment may be quickly effected even in the field as conditions warrant . the invention of the present disclosure is not limited to the particular structure shown but may be utilized with various other cultivators and may be used independently of any cultivator or row crop operation . it should be understood that i wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art .