Abstract:
A fertilizer knife for use in applying anhydrous ammonia comprising a leading edge having a flat face. A projecting shoe attached to the leading edge that is flat to minimize packing of soil against furrow sidewalls. A fertilizer delivery tube disposed on a back edge of the knife having a bend portion adjacent the bottom surface of the projecting shoe leading to a fertilizer release hole under the bottom surface of the knife.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    Fertilizer knives are used with agricultural implements known as ammonia applicators in the trade.  
           [0002]    Fertilizer knives are attached to an implement and can be used during different times from prior to planting to post emergence. Applicant has supplied various knives to the trade that have become popular and been copied by many competitors. A good ammonia knife places the ammonia in the soil and seals it there with dirt.  
           [0003]    U.S. Pat. No. 4,132,181 shows a common knife useful for placing ammonia. The knife has a cast point  3  to resist wear and a tube  8  that releases ammonia substantially below the level of the soil. The idea is that after the knife passes soil will fall back into the furrow created as the knife is pulled through the soil and thereby seal the ammonia underground instead of allowing it to escape into the air. Patent &#39;181 characterizes several of the problems with prior art knives. First, the long curved front  3  tends to throw dirt in a wide path, this is undesirable at any time but cannot be tolerated once plants have emerged. After plant emergence, the thrown soil covers the small plants stunting or killing them. A second problem is that while the sharp point  2  seems like a good idea, use rapidly wears off the point and requires replacement. Another problem with this knife is the knife profile (FIG. 3), which is tapered from front to back. This tapered profile will pack soil against the sidewalls of the furrow as the knife passes through the soil. By packing the soil, the knife leaves an opening that much of the ammonia will escape from. The knife of patent &#39;181 might trap ammonia effectively in some soils, but in damp or clay soil it will be ineffective and allow too much ammonia to escape causing unwanted pollution as well as an economic loss to the farmer.  
           [0004]    As mentioned a knife like &#39;181 has a very limited ground speed in a post emergence environment. A knife such as &#39;181 is limited to much less than 2 miles per hour in post emergence corn for example. If the knife travels any faster than 2 miles per hour the soil thrown by the curve of the knife will do too much damage to the young plants. Knives such as &#39;181 also have a problem of allowing ammonia to escape back out adjacent to the tube that delivers the ammonia. This occurs because as the knife has the furrow open, there is still an opening up and out into the atmosphere adjacent to the knife so as the ammonia is released into the furrow a portion can escape.  
           [0005]    U.S. Pat. No. 5,452,673 shows an ammonia knife without the front curve. This straight up and down knife will throw less soil than the curved front knife. However, this knife has a profile that also tends to pack soil against the sidewalls of the furrow and will allow the ammonia to escape. Patent &#39;673 attempts to correct that situation by dragging a cover device  40 , known in the industry as a beaver tail, behind it. Many knives will drag something like a plate or chain to improve coverage of the ammonia, however these devices do not work well and can also throw more dirt. These devices drug through the soil also tend to wear rapidly and break off requiring replacement of the knife. The cover device  40  for example, can only cover right at the soil surface as shown, this is not where you want the ammonia which should be trapped several inches deep. Place the cover device  40  deeper and it will throw dirt, provide drag, require frequent replacement and still not cover totally because the knife is packing the soil against the side walls of the furrow as it creates the furrow.  
           [0006]    As can be seen, there is a need for an improved ammonia knife and ammonia application method for farming and particularly for post emergence application, that are economical and effective to use.  
         SUMMARY OF THE INVENTION  
         [0007]    An improved ammonia knife particularly useful in side dressing applications post emergence. The knife is effective in creating a furrow without packing soil against the walls of the furrow such that ammonia placed by the knife can be sealed.  
           [0008]    In another aspect of the knife the wear edges of the knife are flat to minimize wear damage to the knife and to reduce the tendency to pack soil against the sidewalls of the furrow.  
           [0009]    In yet another aspect of the knife soil is lifted and ammonia is released under the knife to minimize the unwanted release of ammonia. The ammonia tube is bent to release ammonia under the knife, and the ammonia is released forward of where the furrow is closing to minimize leakage and effectively seal the ammonia.  
           [0010]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 Shows a side view of the knife, partially exploded;  
         [0012]    [0012]FIG. 2 Shows a view of the front edge of the knife in use and;  
         [0013]    [0013]FIG. 3 Shows a view of the underneath of the knife. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]    The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.  
         [0015]    [0015]FIG. 1 illustrates a side view of the preferred embodiment of the present invention, a fertilizer knife  10  comprising a blank  12 , a casting  13 , tube protectors  14  and a fertilizer tube  18 . The casting  13  includes a soil divider  16 , a leading edge  17 . The hole  23  and slot  24  in the blank  12  are used in mounting the knife  10  to an implement not shown. The fertilizer tube  18  includes a bend  26  near the bottom of casting  13  and the tube  18  includes a hole  28  passing through the tube  18  to allow anhydrous ammonia to flow from both sides of the tube  18  and from both sides of the knife  10 . The knife  10  can be assembled from its component parts by welding as shown.  
         [0016]    [0016]FIG. 1 illustrates that casting  13  allows the tube  18  to bend  26  and pass under the bottom of casting  13 . Placing the ammonia outlet hole  28  under the knife  10  and casting  13  gives it optimum performance in terms of sealing ammonia. Cutout area  30  gives the ammonia the ability to disperse somewhat within the soil. Placing the tube  18 ,  26  within the cutout area  30  protects the tube  18 ,  26  from being crushed when the knife  10  carrying implement, not shown, is placed on a hard surface such as concrete when not in use. Placing the outlet hole  28  of the tube  18  under the shoe  40  prevents ammonia from traveling up adjacent to the tube  18  to escape from the soil. It is common in the prior art for a knife to have a straight ammonia tube and this can lead to ammonia, released under ground, traveling up near the straight tube where it is released into the air. A curved tube  18 ,  26  again leads to a greater amount of the ammonia applied staying underground where it can provide benefit. Releasing the ammonia sideways under the knife  10  makes it almost impossible for the ammonia to leak up adjacent the tube  18  prior to the furrow sealing with dirt.  
         [0017]    [0017]FIG. 2 illustrates the knife  10  in use in soil  100 . The front edge  12   a  of the blank  12  is flat. This design is counter intuitive to most designers who will put a sharp edge on the leading edge of a knife. Experimentation has shown that a flat front edge  12   a  gives two major advantages. First it tends to push the soil and a small amount of soil will accumulate and pack on the flat  12   a  this protects the edge  12   a  from wear and greatly extends the life of the knife  10  with a minimum of increased drag. The second advantage of the flat leading edge  12   a  again comes from pushing dirt. A sharp leading edge tends to pack soil against the sidewalls of the furrow and allow anhydrous ammonia to escape from the furrow. The flat leading edge  12   a  pushes the dirt instead of packing it and this leads to a better seal of the dirt as the knife  10  passes. Soil tends to roll off a flat edge  12   a  as opposed to packing. A net effect of this is that a farmer can get into a field when it is wetter, often several days earlier then would otherwise be possible. The front edge of the casting  13  is also flat  13   a.  The flat  13   a  has the same advantages described for the flat  12   a.  As best shown in FIG. 1 these flat edges  12   a  and  13   a  are nearly perpendicular to the ground  100  when in use. The shoe  40  also has a flat leading edge  17 . FIG. 2 also shows that the top surface  42  of shoe  40  is tilted to provide soil lift as the knife  10  travels through the soil. Since the ammonia is released under the shoe  40 , the lift occurs, creating a tunnel, just as the ammonia is released.  
         [0018]    In FIG. 2 lines w-w indicate the width to which soil will be thrown by this knife  10  compared to wp-wp which indicates a much greater width of soil thrown by prior art knives. The nearly vertical attack of the knife  10  shown in FIG. 1 leads to some of its ability to not disrupt topsoil. Also the shoe  40 , which presents a very small profile  102  in the soil, minimizes soil disruption. The profile  102  indicates a cross section of a tunnel in the soil  100  created by the lift of shoe top surface  42 . This mole like hole profile  102  is where almost all the ammonia applied will be trapped.  
         [0019]    [0019]FIG. 3 shows the bottom of the knife  10 . The shoe  40  portion of the casting  13  includes the opening  30  shown in FIG. 1. It also includes a cylindrical opening  30   a  to accommodate the tube  18  as it passes from bend  26  under the knife  10 .  
         [0020]    In use, as shown in FIG. 2 the knife  10  throws a minimum of soil on top the ground  100 . The lines w-w indicate how far the present knife  10  would throw dirt compared to a prior art knife throw wp-wp traveling at the same speed. For side dressing corn, for example, a prior art knife would be limited to about 2.5 miles per hour. If a tractor pulling the prior art knife traveled faster it would throw dirt far enough, wp in FIG. 2, to cover corn seedlings not shown. In a similar application of side dressing corn an implement pulling the knife  10  can travel up to 6 miles per hour without hurting seedlings. The benefit to the farmer then is a knife  10  that allows the farmer to complete an operation in less than half the time and with superior sealing of the ammonia underground.  
         [0021]    It should be understood, of course, that the foregoing relates to preferred embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.