Abstract:
The present invention relates to a knife for and a method of zero till or minimum till seeding and fertilizing. The knife is particularly adapted for dry land conditions producing minimum solid disturbance and very shallow operation. The knife has a high penetration angle preferably of 45 degrees which permits the blade to enter high trash surface cover with little tendency to plug due to trash accumulation. The blade has a forward angle of attack, the lower cutting edge advancing before the upper cutting edge, serving to make a clean cut in the soil surface without accumulating trash. Seed and/or fertilizer conduits are attached to or incorporated in the trailing face of the blade in which the outlets may be spaced for controlled placement of the materials. By the method a furrow is cut having a substantial transverse component in an operation with a substantial forward component. A preferred embodiment includes a horizontal extension blade for cutting a horizontal swath at a shallow depth through weed growth. Conduits may be secured to the extension to allow greater separation and control of material placement. The knives may be arranged in overlapping configuration on the draw bar to affect weed cutting, seeding and fertilizing of a complete with of soil in a single pass.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This Patent Application is a Divisional of, and claims priority to under 35 U.S.C. §120, U.S. patent application Ser. No. 09/623,847, filed on Jul. 31, 2000 now U.S. Pat. No. 6,952,998, entitled, “Minimum Till Seeding Knife” and having Terry Emerson Summach and Bradley T. Summach as the Inventors. The full disclosure of U.S. patent application Ser. No. 09/623,847 is hereby fully incorporated by reference. 

   FIELD OF THE INVENTION  
   The present invention relates to a method of farming, a farm implement and a knife or knife assembly which may be used as part of no-till or minimum-till farming practices primarily for placement in the ground of seed and/or fertilizer and other materials. The invention works in all field conditions, and in particular it operates with minimum soil disturbance in minimum till and zero till farming practices, better allows passage of trash in such practices, and does not cause the hair-pinning of crop residue as is often caused by disc-type openers. As a result, the method provides a simple, reliable and inexpensive procedure and tool which can be used in all farming practices so that multiple types of equipment are not required by farms for various soil conditions. 
   BACKGROUND OF THE INVENTION  
   Important advantages have been found in soil preparation, and seed and fertilizer delivery in employing no-tilling or minimum tilling methods which cause minimum disturbance to the soil. This is particularly important in dry land conditions where the soil is subject to moisture and topsoil loss if conventional tilling methods are used. 
   It is usually desirable when employing no-till farming practices to disturb the soil surface as little as possible. The surface will be covered with the residue from previous crops, and the surface layer will contain old root structure. This plant material can serve to retain moisture below the surface and to assist in securing the soil against runoff and erosion. Particularly in dry land conditions it is beneficial to retain this covering. Tools available to seed into zero till or minimum till conditions have encountered problems. 
   Fertilizing prior to seeding is a method utilized by some farmers. While broadcasting the fertilizer on the surface is a method that does not disturb the surface, it is very inefficient, as much of the fertilizer can be lost due to runoff surface water. Placement of fertilizer at a level well below the level that seed will be place has been utilized. Tilling and fertilizing is disclosed in Great Britain patent No. 1,574,412 issued to Ede in 1980. In that prior art device an angled tilling blade for deeply penetrating the soil is shown with a central duct and a number of separated orifices for providing fertilizer in vertically separated bands. To maintain those desirable characteristics of the surface structure in zero till conditions major surface disturbance is not acceptable. 
   Zero till devices have been developed to deposit high concentration bands of fertilizer in furrows. If the seed is placed in close proximity to a high concentration of fertilizer, burning of the newly germinated plant will result. To avoid this one technique has been to separate the seeds by a soil layer from the fertilizer. 
   In the U.S. Pat. No. 5,396,851 issued to Beau jot in 1995 fertilizer is deposited by a first vertical blade which cuts a deeper furrow. A second blade cuts a second furrow in which to deposit seed. Other devices such as disclosed in U.S. Pat. No. 4,798,151 issued to Rodrigues in 1989 form a deep fertilizer furrow, and a shallower shelf above the fertilizer on which to plant the seed. In both cases, to minimize soil disturbance only a narrow furrow is cut. It is grown to prepare soil when using traditional tilling methods to cut out weed growth prior to or at the time of a seeding operation. 
   U.S. Pat. No. 1,085,825 issued in 1914 to Rubarth discloses a subsurface tilling blade for use with a traditional turning plowshare. The tilling blade its curved to angle the cut and includes a horizontal blade on the opposite side. The blades are shown to include an arrangement in overlapping fashion to cut the full width of the subsurface to remove weeds and old growth. Seeding and fertilizing are separate operations. 
   U.S. Pat. No. 5,005,497 issued in 1991 to Kolskog discloses a deep banding knife for delivering seed and fertilizer with an additional transverse rod for disrupting weed growth. The banding knife makes a substantially vertical cut in the soil. The rod disrupts the subsoil to loosen soil and cut weeds. The transverse rods can be arranged in parallel to remove weeds completely. 
   Adaptations of these concepts have been used for deep placement of fertilizer in fully tilled row-crop situations. 
   In traditional zero till farming practice, no till furrows are separated by undisturbed areas of soil and weeds. Typically a herbicide application is necessary to control weeds which would otherwise compete with the crop growth and possibly contaminate the harvest. Herbicide is an expensive additional operation. 
   A further problem encountered by seeding implements particularly in zero till conditions is the accumulation of trash during seeding which impairs their operation. Many devices for seeding in zero till conditions provide a blade which penetrates the soil substantially vertically. Trash gathers around the blade and is dragged with the device. This can impair operation. It also removes the desired moisture retaining cover. In an effort to combat this problem the Beau jot discussed above is adapted to lift over obstacles, such as crop stubble, interrupting seeding. Such a technique reduces trash accumulation, but reduces seeding efficiency. 
   A deep sowing tool has been disclosed for rice seeding in relatively wet conditions in USSR patent No. 372,962 issued in 1973 using a tilling blade and deep seed delivery to cover seeds and to reduce the need to water. This is not suitable for zero tilling, as tilling using this tool is deep in order to cause deep soil aeration. The blade of this prior art design penetrates the soil essentially vertically, with an angled blade portion cutting more deeply. The blade portion of this design would also be subject to accumulation of trash. 
   Significant soil disruption occurs as vertical furrow parting tools are drawn through surface soils at relatively high velocity, especially in high trash conditions or with unprepared soils. Additional energy is imparted to the soil, throwing and turning the soil. 
   It is desired for minimum soil disruption to pass through the soil surface and any trash cleanly without undue lifting or turning of the soil. While disk openers have the ability to cut through most trash, some straw will not cut easily, and is pushed into the furrow, a result commonly called hairpinning. This can displace seeds, as well as drying out the seed bed. As well, effective no-till disc opener designs are relatively expensive. 
   The prior art fails to provide teaching to or a suggestion of any method or device for operation in zero or min-till conditions which provides tilling and/or seeding, fertilizing or weed clearing in a single pass without significantly disrupting the soil or the order of the soil structure and avoid hairpinning. It is desired to provide the advantages of tilling seeding and weed clearing without trash accumulation. 
   SUMMARY OF THE INVENTION  
   The invention provides a ground opening knife for use in no-till or minimum-till farming operations primarily in conjunction with seed and/or fertilizer placement adjacent a soil cut-line generally in the direction of travel comprising connection mechanism adapted to mount the knife on a farm implement, and a blade comprising a lower portion, said lower portion adapted to open soils along the direction of travel, said lower portion adapted to extend into the soil but no more than 6 inches measured vertically, said lower portion adapted to be oriented in a direction having a 1 st  component of between 30 and 60 degrees below horizontal in a plane transverse to the said direction of travel, and a 2 nd  component forward in the direction of travel. 
   The knife may include an upper portion adjacent said lower portion adapted to extend away from the surface of the soil and is adapted to pass through materials or residue on the surface of the soil or associated with the passage of the knife though the soil. 
   The knife may also include an extension extending substantially laterally from said lower portion and provides support for material delivery tubes at various locations along the blade and extension. 
   The knife may also include in extension to form a secondary furrow adjacent the said lower portion intermediate the surface of the soil and the lowermost end of the said blade and may include an extension of said leading edge generally forward in the direction of travel. 
   The invention also provides a method of no-till or minimum-till farming operation primarily in conjunction with seed and/or fertilizer placement adjacent a soil cut-line aligned generally in the direction of travel comprising forming a furrow in the soil extending from said soil cut-line no more than 6″ into the soil measured vertically, and forming the said furrow by cutting the soil along a direction having a 1 st  component of between 30 and 60 degrees below the horizontal in a plane transverse to the said direction of travel, and a 2 nd  component forward in the direction of travel. 
   The method substantially minimizes any disturbance of the cut soil either above the said furrow or below it or both whether distribution or particulate or other materials is included at the same time within the furrow being formed. 
   The invention also provides a no-till or minimum-till farm implement primarily for use in conjunction with cultivation or materials placement adjacent a plurality of soil cut-lines generally parallel and in the direction of travel comprising a support frame structure, a plurality of around opening knives attached to said support structure, spaced from each other in a direction transverse to the direction of travel of the implement and each adapted to cut the soil along adjacent ones of said cut-lines, each said knife having a blade comprising a lower portion, said lower portion adapted to extend into the soil but no more than 6 inches measured vertically between the surface of the soil and the lowermost extremity of the said blade, said lower portion adapted to be oriented in a direction having a 1 st  component of between 30 and 60 degrees below horizontal in a plane transverse to the said direction of travel, and a 2 nd  substantial component forward in the direction of travel. 
   The farm implement may include an extension of the blade extending laterally across a substantial portion of said spacing between adjacent said cut-lines when viewed in a plan view. 
   The invention will be more clearly understood to those skilled in the art with the following detailed description of preferred embodiments with reference of the following drafting&#39;s in which: 

   
     BRIEF DESCRIPTION OF THE FIGURES  
       FIG. 1  is a plan view of a single knife according to the present invention; 
       FIG. 2  is a side view of the embodiment of  FIG. 1 ; 
       FIG. 3  is a front view of the embodiment of  FIG. 1 ; 
       FIG. 4  is a plan view of a further embodiment according to the present invention; 
       FIG. 5  is a side view of the embodiment of  FIG. 4 ; 
       FIG. 6  is a front view of the embodiment of  FIG. 4 ; 
       FIG. 7  is an isometric view of the embodiment of  FIG. 4  arranged on an implement for operation; and 
       FIGS. 8-1  through  8 - 3  are front, top and side elevations respectively of another embodiment of the invention adapted for double shooting of materials in seeding. Like references are used throughout to designate like elements. 
       FIG. 9  is a plan view of an agricultural implement for planting seeds. Which incorporates the seeding knives of the invention; 
       FIG. 10  is a horizontal front elevation of an angled seeding knife, in use; 
       FIG. 11  is a side elevation of the knife of  FIG. 10 , from the left side of  FIG. 10 , and  FIG. 11  includes a cross-section on the line X—X of  FIG. 10 ; 
       FIG. 12  is a rear elevation of knife of  FIG. 10 ; 
       FIG. 13  is a right side elevation of the knife of  FIG. 10 ; 
       FIG. 14  is a cross-section of a blade of the knife of  FIG. 10 , the cross-section being taken in a plane at right angles to a knife-edge of the blade; 
       FIG. 15  is a front elevation corresponding to  FIG. 10  of another angled seeding knife; 
       FIGS. 16 ,  17 ,  18  are further elevations of the knife of  FIG. 15 ; 
       FIG. 19  is a pictorial elevation of a replaceable tip, of the knife of  FIG. 15 ; 
       FIG. 20  is an elevation of the body of the knife of  FIG. 15 , and is shaded to show the configuration thereof. 
   

   DETAILED DESCRIPTION OF THE INVENTION  
   The preferred embodiment of the single knife of the present invention is as shown generally at  10  in  FIGS. 1–3 . In  FIG. 1  arrow designated  1  shows the direction of travel of the knife  10  through the soil when working. 
   As shown in  FIG. 7  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  FIG. 7 ). As shown in  FIG. 7 , 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  FIG. 1 ) 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  FIGS. 3 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  FIG. 3  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  FIGS. 1 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  FIGS. 1–3 ) 
   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  FIG. 8  in which  FIG. 8-1  shows the embodiment in a front view,  FIG. 8-2  in a plan view and  FIG. 8-3  is a side elevation. 
   In  FIGS. 8-1  through  8 - 3 , the embodiment is shown in conjunction with the knife and method shown in  FIGS. 1 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  FIG. 8-3 . As seen in the front view of  FIG. 8-1  this will provide a secondary furrow or ledge intermediate the surface of the soil  5  and the lower end  17 .  FIGS. 8-1  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  FIGS. 4–6 . 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  FIG. 7 . 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  FIGS. 4 and 5 , or higher on the angled blade  14  for vertical separation such as for herbicide application nearer the soil surface. 
   As seen in  FIG. 7 , 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  FIG. 7 . 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. 
     FIG. 9  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 . 
     FIG. 10  is front view of one of the angled-knife seeders  123 .  FIG. 10  shows the seeder being dragged forwards, i.e. out of the paper, as indicated by the arrow  132 .  FIG. 11  is a lateral or side elevation, showing the seeder being drawn through the ground, and moving to the left as indicated by arrow  132 .  FIG. 11  includes an inset cross-section, taken on line ++ of  FIG. 10 . It is emphasized that line ++ is vertical, i.e. the inset cross-section in  FIG. 11  lies in a vertical plane. 
   As shown from the front view,  FIG. 10 , 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  FIG. 9 ). 
   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,  FIG. 12 , and in the opposite side-elevational view to  FIG. 11 ,  FIG. 13 . 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. 
     FIG. 14  is a cross-section of the blade  134  and shows the dimensions thereof. The  FIG. 14  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  FIGS. 10 and 12 , but the blade is also given a forward pitch angle  148 , as shown in  FIGS. 11 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. 
     FIG. 15  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  FIG. 1 , 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 ( FIG. 15 ) or the inside ( FIG. 1 ) 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  ( FIG. 15 ),  162  ( FIG. 1 ), between the shank  12  and the angled blade  14 . 
     FIGS. 16 ,  17 ,  18  are other views of the knife of  FIG. 15 . It will be noted that this knife includes a separable and replaceable tip  163 . The tip shown separately in  FIG. 19 .  FIG. 20  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 (FIG.  2 )), or can put the conduit to one side of the shank (which suits casting ( FIG. 16 )). Or, the conduit may be finished lower down, below where the shank is bolted to the mounting bar ( FIG. 11 ), although now the flexible hose might be vulnerably close to the ground. Putting the conduit to one side of the shank ( FIG. 16 ) 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 ( FIG. 8 ) 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.