text: the preferred embodiment of the single knife of the present invention is as shown generally at 10 in fig1 – 3 . in fig1 arrow designated 1 shows the direction of travel of the knife 10 through the soil when working . as shown in fig7 the knife 10 is typically attached to a cultivator - type frame or implement generally indicated at 2 to be towed by a tractor in a direction of travel 1 primarily in cooperation with a tow - between or tow - behind seed supply carrier ( not shown ) having a repository of seed , fertilizer or other material and fluid passages for connection with the knife 10 . the frame 2 is shown in general outline only . the knife 10 includes a shank 12 which serves as a connection for mounting the knife 10 selectively on the implement in a known fashion ( as at 3 in fig7 ). as shown in fig7 , an appropriate spacing 4 for seeding or tilling operations will be selected , determining the number and spacing of knives 10 mounted across the width of the implement . the shank 12 preferably has a pair of holes 13 ( see fig1 ) for mounting bolts or the mounting could be provided in any conventional manner such as a knock - on taper mounting system or other known mounting mechanism . knife 10 includes a blade 14 formed to penetrate the soil along a soil - cut line 11 oriented in the direction of travel . penetration of the soil occurs at an angle a which has both substantial lateral ( a 1 ) and forward ( a 2 ) components as shown in fig3 and 1 , respectively , of approximately 35 – 55 degrees to the surface 5 of the soil to be tilled . preferably each of lateral and forward components a 1 and a 2 respectively is 45 degrees . soil penetration ( d ) is by the lower portion of the blade 14 as at 6 in fig3 and is no more than 6 inches , consistent with minimum till or no till farming practices . the lateral component a 1 of angle a determines the final angle of the furrow cut into the soil . the angled furrow allows seed to be planted ensuring soil cover . the blade is also angled significantly forwardly by component a 2 of angle a . preferably , a lower end 17 of a cutting edge 16 is significantly in advance of the upper end 15 of the cutting edge 16 . deeper soil is cut and lifted in advance of cutting the surface soil allowing the surface to be cut along cut - line 11 more easily and without undue lateral disruption . vertical motion is limited . the forward component of angle a of the blade cuts through the surface and trash layers last without accumulating trash on the knife 10 . leading edge 16 is preferably continuous form its lower end 17 to its upper end 15 . the blade 14 had a leading cutting edge 16 and a pair of opposing angled surfaces 18 a and 18 b which form a wedge shaped profile . the profile shape is determined by the furrow opening required . edge 16 may be in 2 parts , one below the surface and another above , but preferably extends continuously above the surface sufficient to move trash and other materials aside without accumulation . also preferably it is formed aligned with the leading edge of the lower portion of the blade 14 . preferably surface 18 b is inclined slightly from the horizontal to avoid sliding contact with the soil below the blade 14 and minimize soil disturbance below the cut . also preferably , the rear surface of blade 14 is also angled forwardly and downwardly so as to assist in the creation of a small temporary cavity behind the blade as it travels through the soil . the overall effect is to provide a method and knife whereby primarily vertical motion is imparted to the soil to permit the blade 14 passage and then a return substantially vertical motion is permitted whereby the soil may return to its approximate original location . adjacent the trailing surface 20 of the blade 14 , a conduit 22 may be secured for delivering seeds or other material . the conduit 22 may have an outlet 24 near the lower end 17 of the blade 14 as shown in fig1 and 2 , and as a result the outlet 24 is adjacent the lowest area of the furrow cut by the blade 14 . the seed delivery conduit 22 is protected from damage as the blade 14 is advanced through the soil by the blade body 14 . the outlet 24 is also shielded from becoming clogged with earth by this arrangement . additional conduits along the blade for fertilizer , herbicide or other materials may be similarly located ( not shown in fig1 – 3 ) the preferred method provides the steps of forming an angled no - till or minimum till furrow by a knife 10 which furrow cutting motion has both a substantial forward and a substantial lateral component both above and below the ground to a depth ( d ) of 6 inches . in a preferred method , seed and fertilizer are scattered from adjacent outlets in a pattern across the width of the furrow . the outlets may be spaced apart to appropriate depths and separation , for example , placing fertilizer outlet at the lowest end of the blade for the deepest application and a seed outlet spaced above it on the angled blade 14 . another preferred embodiment is shown in fig8 in which fig8 - 1 shows the embodiment in a front view , fig8 - 2 in a plan view and fig8 - 3 is a side elevation . in fig8 - 1 through 8 - 3 , the embodiment is shown in conjunction with the knife and method shown in fig1 to 3 with an additional double shoot extension 8 . leading edge 16 of the lower portion 7 is extended further forward and downward as best depicted in fig8 - 3 . as seen in the front view of fig8 - 1 this will provide a secondary furrow or ledge intermediate the surface of the soil 5 and the lower end 17 . fig8 - 1 through 8 - 3 show this embodiment as forming a v - shaped furrow particularly suited to the deposit of particulate material such as seed which would be retained in this groove . the extension 8 could have other shapes to form a ledge or other shape as required . an extension 8 depends from the leading edge 16 and may be provided with a delivery conduit 19 . this double shoot method forms a seed or other material positioning shelf or secondary furrow within the angled furrow with a specific spacing from the lowermost extremity . an alternate embodiment of the invention is shown in fig4 – 6 . the knife 10 includes a blade 14 as described above . the knife 10 further includes an extension blade 30 that extends substantially horizontally form the blade 14 preferably at its lowermost end 17 . the extension blade 30 has a leading cutting edge 36 , which preferable forms a continuation of or 3 rd part if also the leading ledge 16 . edge 36 is substantially horizontal and is preferably oriented transverse to the direction of travel . the cutting edge 36 is formed between an upper surface 32 angled upwardly and rearwardly and a lower surface 33 which is substantially horizontal . the lower blade surface 33 may preferably be angled to the rear , upwardly about 2 degrees , or notched , to reduce drag . the extension blade 30 increases the width of the knife 10 as shown in fig7 . this extends the cultivating and / or planting area for greater seed bed utilization , or may be selected for greater spacing between seed planting while still effectively cutting existing plant roots to condition more of the width of soil . the extension blade 30 may be varying in width for different spacing considerations . outlets for seed , fertilizer and other addictives may be spaced apart in or on the extension blade 30 to form distinct rows ( not shown ) and are preferably adjacent the rear surface thereof or may provide for broadcast across the width of extension 30 . outlets may also be placed at the corner between the angled blade 14 and the extension 30 as shown in fig4 and 5 , or higher on the angled blade 14 for vertical separation such as for herbicide application nearer the soil surface . as seen in fig7 , a plurality if knives shown including extension 30 on an implement frame in outline may be arranged spaced in continuous or overlapping arrangement on the implement 2 so that the full width of soil is conditioned . the number and spacing will depend on the crop and planting conditions . suitable placement of outlets along extension 30 would result in a generally scattered seed and fertilizer delivery in behind each knife 10 . in this case the complete width of the soil may also be cut by the blade extension without being dragged and fouling the knife 10 . the extension blade 30 may be positioned to travel under the path of the angled blade 14 of the adjacent knife 10 . knives 10 are mounted to an implement or cultivator frame 2 as in fig7 . a wing section of the frame 2 is illustrated in outline form . additional central and wing sections are not shown . the frame 2 is carried on loads bearing wheels ( not shown ) which support the frame 2 in a raised position for travel and in operative position . adjustment of the height if the frame 2 in a known fashion accurately controls furrow depth ( d ). depths ( d ) may typically range from ½ inch to 4 inches or up to 6 inches . alternatively , a ground following linkage may be used to attach each knife 10 to the frame 2 , with the depth being controlled by a wheel attached to each knife assembly . in use , the knifes 10 arranged in parallel fashion on an implement or overlapping arrangement on an angled draw bar are drawn by a tractor together with a seed carrier provided with reservoirs of seed and fertilizer material and a fluid delivery system operatively connected with the conduits 22 on the knives 10 . the frame 2 is advanced with the leading cutting edges 16 and , optionally , edge 36 facing in the direction of travel 1 . the deposit of material is controlled by the speed of advance of the tractor in a known fashion . the knife 10 will not normally produce overlapping furrows without the blade extension 30 being present , or being long enough to result in an overlapped cut with adjacent rows as the placement would be too close . weed control with herbicides is necessary in those circumstances . as seeding occurs , fertilizer can be added simultaneously in controlled concentration , or at a desired depth or spacing from the seed . fertilizer is more efficiently used without loss from runoff . further fertilizer is placed to be available to the crop and not at the surface for weeds . a substance delivery of fertilizer is particularly effective if gaseous fertilizer , such as ammonia , is used . the knife provides a variety of options for placement with minimum adjustment and cost . it may be desired to seed an area progressively in time for continuous harvest . or with different additives , or with different crop . since the process is a complete single pass operation , each seeding will include complete weeding and fertilizing more accurately than if separate steps are made which might leave areas untouched . the invention may also be used as a light tilling tool for minimum soil disturbance without seeding or fertilizer outlets . this would cut weeds and provide minimum soil aeration . the knife advantageously does not turn the soil which would incorporate weed seeds from the surface into the soil to germinate . additional embodiments of the present invention will be apparent to persons of skill in the art . fig9 is a plan - view diagram of an implement 120 which carries thirty - five angled - knife seeders 123 in four rows . the implement 120 has a centre section 124 , and two hinged wings 125 . the wings 125 can be folded upwards for road - transport and storage of the implement . the centre section 124 includes a hitching mechanism 126 whereby the implement can be towed by a tractor . it will be noted that some of the angled - knife seeders 123 slope to the left , and some to the right . thus , there is no , or only a small , net sideways force on the implement . the left seeders and the right seeders are kept separate . in banks , since the configuration of the seeders is not suitable for close - pitched left - right mountings thereof . press - wheels 127 are provided . one in - line behind each seeder . to roll over . and to close the ground . after the seeds have been deposited by the seeders . the seeders are attached each to a respective mounting bar 128 , which is suspended from the frame 129 of the implement , the suspension mechanism including the usual break - back - spring mountings 130 . fig1 is front view of one of the angled - knife seeders 123 . fig1 shows the seeder being dragged forwards , i . e . out of the paper , as indicated by the arrow 132 . fig1 is a lateral or side elevation , showing the seeder being drawn through the ground , and moving to the left as indicated by arrow 132 . fig1 includes an inset cross - section , taken on line ++ of fig1 . it is emphasized that line ++ is vertical , i . e . the inset cross - section in fig1 lies in a vertical plane . as shown from the front view , fig1 , the seeder or knife 123 has an angled blade 134 which extends down into the ground to a depth , typically of about 10 cm . the depth is determined by the needs of the type of seeds being planted ; planting seeds deeper than 10 cm would be unusual , and 15 cm can be regarded as a maximum planting depth . the angled knife cuts an angled slit - opening in the ground , and the seeds are deposited therein . the seeds to be planted are sullied from a hopper on the implement , and are blown along a hose by mechanism of a fan which forces an air flow in the hose . the hoses are of flexible plastic tubing , one for each seeder ( the hoses are not shown in fig9 ). each flexible hose is clipped to a respective conduit 135 , which is built into the seeder 123 . the conduit is structurally integrated into the back - side of the angled - knife - blade 134 , and runs down the back - side 136 of the blade . the conduit ends in a discharge mouth 137 , from which the seeds emerge , and fall down into the slit - opening . the discharge mouth 137 is near the bottom of the knife blade , whereby the seeds are deposited more or less at the bottom of the slit opening . the conduit 135 is shown in the rear view of the seeder , fig1 , and in the opposite side - elevational view to fig1 , fig1 . the upper end of the conduit terminates at a port 138 , into which the flexible hose can be secured . the knife blade has an over - surface 139 and an under - surface 140 . these surfaces are respective flat planes which meet at a line , that line being the knife - edge 142 . the blade is generally triangular in cross - section . in that the surfaces 139 , 140 slope back from the knife edge , to a maximum thickness of the blade at the back - side 136 thereof . the conduit 135 is accommodated within the thickness of the back - side of the blade . fig1 is a cross - section of the blade 134 and shows the dimensions thereof . the fig1 cross - section is taken in a plane at right angles to the knife - edge . the dimension 143 is the distance between the over - surface 139 and the under - surface 140 at the back - side if the blade , which in this case is 32 mm ; and dimension 145 is the distance from the knife - edge 142 to the mid - point of the conduit 135 , which in this case is 70 mm . the conduit 135 has an internal diameter if 24 mm . the angle between the over - surface 139 and the under - surface 140 , in the cross - section at right - angles to the knife - edge , is called the wedge angle 146 , which in this case is 25 degrees . not only is the angled blade 134 angled to the side , at a side - slope - angle 147 , as shown in fig1 and 12 , but the blade is also given a forward pitch angle 148 , as shown in fig1 and 13 . in this case , the side - slope angle 147 is 45 degrees , and the forward pitch angle is also 45 degrees . the leading knife - edge 142 is positioned such that when the blade is viewed from in front . only the over - surface 139 can be seen . the under - surface 140 is invisible . that is to say , the knife edge is at the lowermost point of every vertical cross - section taken through the blade 134 . thus , the portion of soil that lies in the path of the blade lies in the path of the over - surface 139 of the blade . the over - surface has the wedge angle 146 , and the soil is therefore driven upwards , by the wedge angle . the uplift travel of the soil is determined by the vertical height 149 of the over - surface 139 , as presented to the oncoming soil , which in this case is about 8 cm . fig1 is a front elevation of another design of angled - knife seeder 150 . in this case , the above - ground portion of the seed conduit 152 is positioned to one side of the above - ground shank 153 . this location of the conduit provides access for the nuts and bolts which are used at 154 to fix the seeder to the mounting bar 128 . however , although access for the nuts and bolts is good , the extra width of the shank 153 can be obtrusive , and can cause soil debris created by the passing of the angled blade to hang up ; such that the wide shank 153 can act like a bulldozer blade . a deflector surface 156 is provided , for deflecting soil debris away from the front face of the shank 153 . the deflector surface 156 is angled to deflect the debris downwards , and to the side . the nub 157 serves also to break the upward flow of the debris , and to keep the shank 153 clear . it may be noted that in fig1 , the triangular gusset - surface 159 was disposed at an angle that included a downwards component , and so the gusset - surface 159 also served to deflect up - flowing debris downwards , and sideways , away from the shank 12 of the knife . thus , the deflector - surface can be on the outside ( fig1 ) or the inside ( fig1 ) of the angle between the shank and the blade . providing downward - facing deflector surfaces on both the inside and the outside also is possible , except that the designer should take care that the knife is not weakened thereby , at the transition 160 ( fig1 ), 162 ( fig1 ), between the shank 12 and the angled blade 14 . fig1 , 17 , 18 are other views of the knife of fig1 . it will be noted that this knife includes a separable and replaceable tip 163 . the tip shown separately in fig1 . fig2 is a shaded view of the back of the body 164 of the knife , and shows not only how the conduit in this design is molded into the shape of the knife , but shows also a spline 165 on the body , which forms the mounting base for the replaceable tip 163 . the tip 163 is held to the spline 165 by mechanism of a pin which engages the pin - receiving - hole 167 . the spline 165 is prism - shaped , having a triangular cross - section like that of the blade itself , but smaller , and the tip 163 includes a socket that is complementary to the conduit 152 . once pinned in place , the tip 163 is very securely constrained against all modes of movement relative to the body 164 . the pin serves only to keep the tip from falling down the spline , but the force tending to make the tip 163 move in that mode minimal : all the heavy forces between the tip 163 and the body 164 are supported by the chunky spline 165 . the conduit 152 continues inside the spline 165 . it is important that the seeds are deposited close to the bottom of the cut opening ; with the conduit inside the spline , even though the bottom part of the knife comprises the tip , the conduit goes to the bottom of the opening . ( it would be inefficient to cut the opening deeper that the planting depths of the seed , so the discharge mouth of the conduit should be as near the bottom of the knife as possible .) on the other hand , the prudent designer would seek to avoid calling for the manufacture of a ( tubular ) extension of the conduit in the tip casting . putting the conduit in the spline puts the discharge mouth of the conduit more or less at the bottom of the trench , even though the knife has a replaceable tip . it will be noted that the lower extremity 168 of the knife edge 169 on the body 164 is rounded convexly , whereas the upper extremity 172 of the knife edge 170 on the tip 163 includes a tag 173 which is rounded concavely . thus , debris traveling up the knife edge can readily pass smoothly over the transition between the two knife edges 16 , 170 . the designer should see to it that the knife edges do not contain interruptions , upon which soil - debris could be snagged . forming the body 164 with a large convex radius is easy from the casting - manufacture standpoint ; it is much easier to control the quality of a concavely - curved tag on the tip casting than on the body casting . the knife edge 170 in the tip 163 can be blunter than the knife edge 169 on the body 164 . the tip 163 operated more deeply , where debris , even if imperfectly cut , tends to be brushed off the knife edge 170 by the pressing passing soil . on the body 164 , the knife edge 169 itself has to do all the cutting of debris and vegetation , with little assistance from the passing soil , since , being shallower , the passing soil might more easily be deflected . it is noted that , if it happened , a hang - up of imperfectly cut material on the knife edge would be a quite serious problem , as it would quickly lead to disruption and disturbance of a large area of soil around the slit opening . conventionally , when seeding has been done with seeding knives ( as opposed to discs , etc ) the seeding knife has been held vertically . when the seeding knife is held at a side - slope - angle , as described herein , the manner in which the soil is opened for receiving the seeds is considerably changed . when the knife is at a side - slope - angle of about 45 degrees to the horizontal , what happens is that a flap 174 of soil is lifted temporarily by the passing blade 134 , and then the flap is lowered gently back after the seeder knife 123 has passed . as a result , the layers of the soil are preserved , during seeding . in other words , it is possible for a farmer to plant seed without disturbing the stratification of the soil . it may be noted that the press wheels 127 serve to press the flap 174 back down , and assist in the maintenance of stratification : thus the function of the press wheel is more in harmony with the action of the angled blade , than in the case of a press when linked with , for example , a non - angled ( vertical ) seeding knife . maintenance of soil stratification is important in currently - favored minimum - till farming regimes , because moisture in the layers a few centimeters down is not dissipated ; weed seeds on the surface remain on the surface and do not germinate ; and stalks and vegetation at the surface remain intact , providing cover and moisture retention . on the other hand , the angled knife , especially when a wing extension is provided below ground , cuts and severs the roots of any vegetation that might be present , whereby weeds and unwanted plant growth are destroyed simply by mechanical action . using herbicide to destroy weeds is expensive and can be dangerous , and has to be done as “ reach ” of the angled knife can be enough to sever the roots of weeds and other growth not only around the seed openings , but over the whole area of ground between the openings . the fact that the flap of soil is pushed upwards by the angled blade does not mean that the soil is compressed : if the soil were pushed downwards or sideways , it would become compressed and perhaps smeared , since there is no where for the deflected soil to go ; but when the soil is urged upwards , the soil simply moves upwards . of course , lifting deeper soild would involve lifting the weight of all the soil above , so lifting without compression only works down to shallow depths . thus , it would not be possible to lift a flap of soil without compressing it if the soil were more than 10 or 15 cm deep . but it is recognized that seed planting is done predominantly at shallower depths than that ; and it is recognized that the depths down to which an angled blade can cause the soil to simply lift without being compressed is a suitable depth to enable planting of nearly all types of seeds . if the knife were nearly vertical , i . e . if the knife were angled over at more than about 60 degrees to the horizontal , the lifting action that occurs with the angled knife would become negligible . with the 45 - degree angle , most of the movement of the soil that occurs is a riding up of the soil over the front edge of the knife . at an angle of 60 degrees , the soil tends to be bulldozed , or chiseled , rather than slit or cut . insofar as the soil is pushed to the side by the knife , the soil is compressed , and smeared , rather than gently lifted . of course , the knife must emerge from the ground surface , and the very shallow soil around the point of emergence inevitably is lifted too much , and tends to fly away . however , this effect is less disturbing than inserting a vertical chisel into the ground . if the knife were more nearly horizontal , this fly - away lifting of the shallow soil might be too much . besides , if the knife were nearly horizontal , although the knife would still lift the flap of soil , the knife blade would need to be too long in order to get down to the seed planting depth , which would mean that too much soil was being moved for a given planting depth , and which would be poor mechanically . tests have shown that the slap - lifting , stratification - maintaining , advantageous effects of the angles blade are largely lost if the blade is angled ( i . e . the side - slope - angle ) more than about 55 degrees or less than about 35 degrees . 60 degrees and 30 degrees can be regarded as the practical limits . it has been found that the force required to draw the angles blade through the ground is at a minimum when the blade is at about 45 degrees . it may be noted that the minimum draw force is an indication of minimum ground disturbance , which is what makes for minimum - till agriculture . the leading knife - edge of the angled blade should be lowermost into the ground . that is to say , the soil approaching the blade should “ see ” only the over - surface of the blade . thus , all the soil that is deflected is deflected upwards . if some of the soil were driven downwards , or horizontally sideways , it would be compressed or smeared , and seeding is most effective and efficient when the seeds are placed on and in soil that has not just been compressed . the effective but gentle lifting as desired has been obtained with angled blades where the blade has been so presented that the over - surface has been about 7 cm high , measured in a vertical sense , from the leading knife edge to the back of the over surface . ( the thickness of the blade , measured in a plane at right angled to the leading edge , preferably is between 25 and 45 mm .) the angle between the over - surface of the blade and the under - surface , called the wedge angle , is a key factor in determining the lift of the blade , and good results have been obtained when the wedge angle lies between 20 and 30 degrees . preferably , the over - surface should be a single flat plane over its whole area , but it is recognized that it id the front of the over - surface of the blade that is key to the performance , i . e . the front 4 cm of the over - surface contiguous with the knife edge . preferably , the blade is generally triangular as to its cross - sectional shape , the three sides of the triangle being the over - surface , the under - surface , and the back - side of the blade . ( the back - side is not , as shown , a flat plane .) it is recognized that the triangular is a good shape , in that it leads to a suitable angle for the over - surface of the blade , in order for the over - surface to deflect soil dynamically ; also , the bottom face can be easily set to not touch the soil passing - by underneath the blade ; also , the bottom face can easily be set to not touch the soil passing - by underneath the blade ; also , the thick back - side has to be thick to accommodate the conduit . in short , the triangular shape is a highly efficient shape for performing the soil - moving operations required for seeding , for accommodating the seed conduit , and ( not least ) is a food shape for providing mechanical strength and rigidity in just the right amounts for the task . the designer should see to it that the knife is reasonably short , in the travel direction . length would just lead to extra drag , and perhaps smearing of the soil , the aim should be to combine efficient use of surfaces and angles to give smooth lift - then - fall - back movement of the soil , without disturbing the soil , and while maintaining stratification . the designer should see to it that the surfaces are angled enough , and are long enough for that , and of course the knife has to be strong and rigid enough to be struck occasionally by stones etc without being damaged . it is recognized that the angled blase as described herein is a design that handles these conflicting requirements very advantageously . the conduit preferably should be in the size range of 15 to 25 mm diameter , for proper seed conveyance . it is recognized that such a size of conduit is wee - suited to being located behind the triangular angled blade , as described . the blade surfaces , i . e . the over - surface and the under - surface , slope towards the conduit as two simple flat planes , straight from the knife edge . as mentioned , the functions of the blade require that the blade be wide enough for its surfaces to be so angled as to be effective ; and the blade must also be strong enough ; beyond that , the blade should preferably be short . good results have been obtained when the blade is about 7 cm , or at least between 5 cm and 10 cm , in width , from the knife - edge to a mid - point inside the conduit . the blade should have forward pitch to ensure the soil debris can clear , by riding upwards along the knife edge , and out of the soil . it will happen sometimes that some material are not cut , or not cut immediately , by the knife edge , and will be piled up ahead of the knife edge , thereby blunting the knife edge . the angled knife should have forward pitch to counteract this . of course , conventional vertical seeding knives have had forward pitch . preferably , the seed conduit should be integral with the knife unit . if separate , the conduit has to be attached to the knife unit . the conduit should not get in the way , not least above ground , where the conduit can contribute to snagging of soil debris . therefore , the conduit should lie in line behind the knife . whilst this is clearly achievable below the ground , above ground putting the conduit in line with the knife structure is not so good , because the shank of the knife is attached to the mounting bar by bolts passing through from front to back , and putting the conduit behind the shank would deny access to the bolts / nuts . the designer also want the point of attachment of the flexible seed hose to be high , out of harm &# 39 ; s way , and also wants to provide room for a clip for attaching the hose into the conduit . the designer either can put the conduit on a stalk that protrudes out behind the shank ( which suits fabricated construction ( fig2 )), or can put the conduit to one side of the shank ( which suits casting ( fig1 )). or , the conduit may be finished lower down , below where the shank is bolted to the mounting bar ( fig1 ), although now the flexible hose might be vulnerably close to the ground . putting the conduit to one side of the shank ( fig1 ) gives access to the fixing bolts , but now the front face of shank is thereby widened , so it is even more important to take measures against snagging of the above - ground soil debris on the shank . one of the benefits of the angles blade configuration lies in the ability to deposit two types of items simultaneously , e . g . seeds and fertilizer , which preferably should be kept spaced apart , upon planting . simultaneous deposition of both seeds and fertilizer ( fig8 ) is simplified by the fact that the knife is at an angle , while ensuring same are kept spaced apart . if the knife were vertical , both items would fall to the bottom of the trench , and it would be difficult to keep the items apart . on vertical knife seeders , it is conventional to provide side ledges ; for fertilizer , however , the protrusions on the vertical knifes that produce such side ledges have also compressed the soil . generally , the farmer wishes to plant as many rows of seeds as possible in a single pass if the seeder implement . in one of the machines described herein , thirty - five seeders are provided on a single implement . the smallest number that might practically be contemplated would be about eighteen seeders per implement . the large number of seeders is appropriate for single - pass seeding operations at shallow depth , in that a tractor can easily provide the force necessary to draw a large number of shallow seeders through the ground . this may be contrasted with the conventional usage of angled cutters to break up hard - pan sub - soil , i . e . caked clay and soil some 50 cm or more below ground . sometimes , these deep angled - cutters have been used to prepare ground for seeding , but in that case the seeding has been done separately , as a follow - up seeding operation , using conventional seed drills . ( breaking up hard - pan also can be done for other purposes , e . g . to improve drainage .) the conventional large , deep , hard - pan angled - cutters were angled simply in order to cover more ground . they were constructed so as to cause maximum disturbance to the soil , at a large depth ; they required large forces to draw them through the ground , so that only a small number , say four to five , could be pulled by a tractor . the use of an angled blade as described herein to lift shallow flaps of soil with minimum disruption , and to lower the soil flap back down without disturbing stratification , makes a clear contrast with the use of deep angled cutters to break up hard - pan . it is emphasized that the gentle , minimum - till , operations described can take place only at shallow depths . in the above aspects , the invention is defined by reference to an implement , in which the angled blades are mounted for operation , in another aspect , the invention can be defined with respect only to the knife unit itself , independently of the implement . in this case , the definition makes use of the shank of the knife , and of the axis of the shank . when the shank is provided with two bolts , one above the other , for attachment to the mounting bar , the shank axis ( in a frontal view of the shank ) is the line that runs through the bolts . however , even if the shank is mounted by mechanism other than two bolts vertically in - line , the shank still has an axis , which can be determined by the geometry of the shank in a particular case . the major features of the invention , the blade lies at an angle to the shank in front view , and the shallow depth of the blade , are present in this definition . as mentioned above , sometimes the conventional vertical knife seeders have included , as an accessory , a mechanism for providing a side ledge to the vertical trench . as mentioned , grains of fertilizer are deposited on or in this side ledge , whereby the fertilizer can be kept spaced apart from the seeds . the fertilizer rests on the ledge , while the seeds fall down to the bottom of the vertical trench . an example of such vertical - knife - with - side - ledge structure is depicted in canadian patent publication ca - 2 , 099 , 555 ( henry , 1995 ). henry &# 39 ; s structure includes a first conventional vertical knife - blade , for cutting a vertical slit in the ground , with the associated delivery pipe for depositing seeds at the bottom of the vertical slit . henry also shows a ledge - cutting accessory . the accessory is fixed to the back of the vertical knife - blade . thus , in the design of henry , two injectors are shown : one for injecting seeds , and the other for injecting fertilizer . regarding henry &# 39 ; s vertical knife - blade cutter / fertilizer - injector : when viewed from the side , henry &# 39 ; s knife blade is angled , such that the bottom extremity of the knife - blade leads the rest of the knife - blade as the knife - blade travels through the ground . it is conventional , and very common , for vertical seeding - trench knife - blades to be angled forwards , i . e . bottom - edge leading . in the front view , henry &# 39 ; s knife - blade is not angled at all . regarding henry &# 39 ; s side - ledge cutter / fertilizer - injector : when viewed from the side henry &# 39 ; s ledge - cutter is so angled as to be “ bottom - edge - trailing ”. that is to say , the bottom extremity of the ledge - cutter lags , or trails , as the ledge - cutter travels through the ground . in the front view , henry &# 39 ; s ledge - cutter makes an angle to the horizontal of about 45 degrees . neither of the blades or cutters of henry will achieve the “ gentle up - and - over ” effect , which is the aim of the present invention . this is because neither of the blades or cutters of henry has an over - surface and an under - surface , which meet at a line , where the line defines the leading knife edge of the blade , and where the knife edge , thus defined , has a side - slope angle of between 30 degrees and 60 degrees . defined with the respect only to the knife unit itself , independently of the implement . in this case , the definition makes use of the shank of the knife , and of the axis of the shank . when the shank is provided with two bolts , one above the other , for attachment to the mounting bar , the shank axis ( in a frontal view of the shank ) is the line that runs through the bolts . however , even if the shank is mounted by mechanism other than two bolts vertically in - line , the shank still has an axis , which can be determined by the geometry of the shank in a particular case . the major features of the invention , that the blade lies at an angle to the shank in front view , and the shallow depth of the blade , are present in this definition .