Abstract:
An agricultural growth control device ( 2 ) includes an organic, biodegradable, layer ( 6 ) and an impermeable sheet ( 4 ) affixed to the underside of the organic layer to form a unitary ground collar ( 8 ). The ground collar defines at least one hole ( 10 ) to allow growth of a plant (P) therethrough while suppressing the growth of weeds or grass around the plant. The impermeable sheet is preferably formed from a slurry of cellulosic fiber and water and the organic layer is preferably formed from a slurry of fiber, water and finely chopped organic material, such as straw, manure, leaves or almond wood chips. The fiber and chopped organic material provide a semi-rigid mulch cover for suppressing weeds around the plant. The mulch cover is easily positioned around the plant and, once it is so disposed, will be relatively impervious to severe weather, such as heavy rainfall and winds. The chopped organic material, particularly almond wood chips, enhance the appearance of the mulch cover.

Description:
This application is a continuation of Ser. No. 08/646172, filed May 7, 1996, now abandoned, which is a division of Ser. No. 08/538693, filed Oct. 3, 1995, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to plants generally, and more specifically to a multi-purpose device for suppressing weeds and enhancing plant growth. 
     Crops, plants, trees and vegetables growing on commercial farms or in municipal and household gardens must constantly battle weeds for survival. Undesired growth of weeds, grass and the like in the region immediately adjacent the stems or trunks of plants and trees is both unsightly and difficult to control because ordinary mowers and other cutting devices cannot efficiently cut such undesired growth. 
     Although there are existing chemicals that can be used to preferentially kill the weeds, these chemicals are typically harmful to the environment. Other methods of suppressing weeds, such as positioning plastic or cloth weed guards as barriers around plants and crops, are expensive and they also can be harmful to the environment because plastic and cloth are generally not biodegradable. Less harmful or biodegradable weed barriers, such as newspaper or cardboard, are typically swept away by the wind or a heavy rainfall. 
     Another problem faced by farmers is disposing of the waste byproducts that result from growing food products on farms. For example, almond growers must destroy massive quantities of wood pruned from their trees every year. Burning the wood is harmful to the environment and cogeneration plants have become too expensive. What is needed is a relatively inexpensive method of discarding farm waste products, such as almond wood chips, without harming the environment. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an agricultural growth control device for suppressing weeds and enhancing plant growth. The growth control device will effectively inhibit the growth of ground cover, such as weeds and grass, around the base of plants, trees or other vegetation. In addition, the device will enhance the growth of the plant by collecting rainwater and gradually introducing nutrients or fertilizers into the soil around the plant. The device of the present invention also provides a relatively inexpensive method of discarding farm waste products, such as almond wood chips, without harming the environment. 
     The agricultural growth control device includes an impermeable sheet containing at least one hole and an organic, biodegradable layer affixed to the top side of the impermeable sheet. The growth control device has at least one hole cut through the impermeable sheet to allow growth of a plant therethrough while suppressing the growth of weeds or grass around the hole. The impermeable sheet preferably formed from a slurry of cellulosic fiber, such as newspaper or cardboard, and water. The organic/acetic top layer is preferably formed from a slurry of paper, water and finely chopped organic material, such as straw, manure, leaves or almond wood chips. 
     One of the advantages of the present invention is that the fiber and chopped organic material provide a semi-rigid mulch cover for suppressing weeds around the plant. The mulch cover is easily positioned around the plant and, once it is so disposed, will be relatively impervious to severe weather, such as heavy rainfall and winds. The chopped organic material, particularly almond wood chips, enhance the appearance of the mulch cover. In addition, the entire device will eventually (within a few months) decompose into the soil, thereby providing an easy, non-harmful method of disposing of these wood chips. 
     The present invention also provides a unique method for manufacturing the agricultural growth control device. The impermeable sheet is formed by grinding a secondary cellulosic fiber, such as paper, into water to form a slurry. The paper slurry is then drained, rolled and pressed on a belt to remove as much of the moisture as possible, forming a semi-rigid first layer. The organic layer is formed by mixing the chopped up almond wood chips (or other organic material) with paper into a second slurry. This second slurry is applied to the first layer and the combination is pressed to eliminate moisture and then baked to create the final semi-rigid product. The paper helps the wood chips stick together and helps the second layer stick to the first layer. 
     The semi-rigid product can be individually tailored for large farms or for individual trees, plants or vegetables. For example, a square or rectangular piece with a relief or hole in the center may be placed onto the ground over a seed so that a plant can grow through the mulch cover, but weeds cannot. In addition, a curvature can be formed in the mulch cover to cause rainwater to flow towards the plant, rather than into the soil, thereby conserving the water. The impermeable sheet may also include soil nutrients, chemical fertilizers or other water soluble soil-conditioning agents imbedded therein. These agents will gradually seep into the adjacent soil to enhance the growth of the plant. 
     In a specific configuration, the almond wood chips and fiber are chopped into fine pieces by a chip cutter before they are mixed with the water to form a slurry. The chip cutter comprises an axle shaft connected to a cylindrical base assembly made of a plurality of pipes extending through circumferentially spaced holes in annular spacer disks. A plurality of cutting blades are slidably and rotatably mounted to the pipes. The cutting blades are mounted between the spacer disks along each pipe and extend in both the circumferential and longitudinal directions. The axle shaft is coupled to a motor for rotating the base assembly and the cutting blades around the longitudinal axis. The organic material and/or newspaper can then be fed into the rotating blades and cut into finely chopped pieces. 
     The above is a brief description of some deficiencies in the prior art and advantages of the present invention. Other features, advantages and embodiments of the invention will be apparent to those skilled in the art from the following description, accompanying drawings and appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a perspective view of an agricultural growth control device manufactured according to the principles of the present invention, illustrating one potential use for the device; 
     FIG. 2 is cross-sectional view of the agricultural growth control device taken along lines  2 — 2  in FIG. 1; 
     FIG. 3 is a schematic view of a method of manufacturing an agricultural growth control device according to the invention; 
     FIGS. 4A-4C are schematic views of alternative embodiments of the agricultural growth control device of FIG. 1; 
     FIG. 5 is a partial side cut-a-way view of a chip cutter according to the principles of the present invention; 
     FIG. 6 is a side cross-sectional view of a portion of the chip cutter FIG. 5 connected to a multiple belt pulley for rotating the chip cutter; 
     FIG. 7 is a front sectional view of the chip cutter of FIG. 5; and 
     FIGS. 8-10 illustrate one of the cutting assemblies of the chip cutter of FIG.  5 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in detail, wherein like numerals indicate like elements, an agricultural growth control device  2  is shown constructed according to the principles of the present invention. Agricultural growth control device  2  generally includes an impermeable sheet  4  bonded to the underside of a biodegradable, organic top layer  6  to thereby form a unitary ground collar  8  for disposition around the base of a tree, bush, plant or other vegetation. 
     Referring to FIG. 2, impermeable sheet  4  and organic layer  6  each include an opening aligned with each other to form a central hole  10  through collar  8 . Hole  10  allows a plant to grow through device  2  and preferably has a diameter of ½ to 3 inches. Of course, hole  10  may be larger if, for example, ground collar  8  is disposed around large trees or bushes. Organic layer  6  preferably has a concave upper surface  12  that slopes downward towards hole  10 . Likewise, the impermeable sheet  4  has a generally concave shape and a relatively planar lower surface  14  so that the thickness of the central portion of collar  8  is substantially less than the thickness of the perimetrical edge of collar  8 . Concave surface  12  of biodegradable sheet  6  and the concave shape of mat  4  allow rainwater to flow radially inward toward central hole  10  and plant P. This facilitates plant growth in dry regions because the plant is able to receive water that otherwise may have been absorbed into the ground surrounding plant P. 
     As apparent from FIG. 1, collar  8  is formed with a slit  14  extending from an outer surface  16  of collar  8  to central hole  10  so that collar  8  can be easily wrapped around the stem of a plant P. Collar  8  precludes undesired vegetation, such as weeds or grass, from growing in the region immediately adjacent plant P. To that end, collar  8  will preferably have a diameter sufficient to block or at least impede the growth of surrounding weeds or grass that will substantially interfere with the growth of plant. This diameter will, of course, vary depending on many variables, such as the surrounding vegetation, the type of plant or the horizontal extent of the plant&#39;s roots under the ground. 
     Impermeable sheet  4  can be of any thickness, but is preferably in the range of ⅛ to 2 inches. The sheet  4  will comprise at least 50% by volume cellulosic fibers and preferably at least 75% by volume cellulosic fibers. Typical suitable cellulosic fibers include secondary fibers, such as paper, disposable diapers, cardboard, newspaper etc. Primary fibers, such as trees, sisal, jute and the like, may also be utilized for impermeable sheet  4 . As discussed in more detail below, sheet  4  is preferably formed by mixing the fibers with water in a slurry and pressing and heating the slurry to form a semi-rigid mat. Other materials, such as seeds, chemical fertilizer, soil nutrients, such as nitrogen, phosphorus and potassium, or other water soluble soil-conditioning agents, can be imbedded into sheet  4 . These materials may be imbedded into the impermeable sheet after it has been dried and pressed or they may be added to the fiber slurry during the manufacture of agricultural growth control device  2 . 
     Biodegradable, organic layer  6  may be formed from a variety of materials that will enhance the appearance of device  2  and will eventually (within a few weeks to a few months) decompose into the soil. In the preferred embodiment, organic layer will comprise waste byproducts, such as straw, manure, leaves or almond wood chips, that result from growing food products on farms. These waste byproducts are typically difficult and often expensive to discard. 
     In a specific embodiment, organic layer will comprise at least 40%, preferably at least 60%, by volume of finely chopped almond wood chips. In addition, organic layer will comprise at least 20% of a paper product, such as newspaper or cardboard. The wood chips and the paper (which act as a binder) are mixed together with water in a slurry and then dried to form a rigid product, as discussed in detail below. The almond wood chips provide an aesthetic appearance to collar  8  and the paper helps the wood chips stick together. The entire layer will eventually decompose into the ground, thereby providing a non-harmful method of disposing of the almond wood chips. 
     It should be noted that the agriculture growth control device of the present invention is not limited to the above configuration. In fact, the device of the present invention can be individually tailored for a variety of different applications. For example, collar  8   a  may comprise a number of separable portions  20 ,  22  (see FIG. 4A) to facilitate the placement of collar  8   a  around larger vegetation, such as a tree or large bush. In this configuration, collar  8   a  may have a variety of shapes other than circular, as is illustrated by the rectangular shape in FIG.  4 A. In addition, sheet  4   b  may include a relief  24  underlying a solid portion  26  of organic layer  6   b , as shown in FIG. 4B. A seed  28  is placed within the relief  24  so that a plant can grow through layer  6   b . Alternatively, collar  8   c  may comprise a number of holes  10   c  for a plurality of plants, such as a vegetable or flower garden (shown bottom side up in FIG.  4 C). 
     The method for constructing collar  8  will now be described with reference to FIG.  3 . The impermeable sheet  4  (shown in FIG. 2) is formed by grinding a paper material, such as newspaper, into water to form a fiber slurry  50 . Preferably, fiber slurry  50  will initially comprise less than 20% by volume of paper material and more preferably about 5% by volume of paper material (i.e., 95% by volume of water). The fiber slurry  50  is then poured onto an endless belt  52  having a number of small openings (not shown) to allow some of the water to immediately drain from fiber slurry  50 . The slurry is pressed by a roller  54  to remove another portion, preferably about 60 to 80%, of the water from slurry  50  to form a partially solidified layer  56 . In addition, suction pressure may be applied to the underside of belt  52  with, for example, a vacuum  58 , to facilitate the removal of the water. 
     A second slurry  60  is then introduced onto the top of solidified layer  56  through a mixer  62 . Second slurry  60  preferably comprises a mixture of about 5-95% by volume of a biodegradable, organic material, such as almond wood chips, and 5-95% by volume of water. Since layer  56  is substantially more solidified than second slurry  60 , the second slurry will generally rest on top of layer  56 . The newspaper helps the slurry  60  stick to the top of layer  56 . At this point, first and second slurries  50 ,  60  are delivered through a vacuum press  64 . Vacuum press  64  removes water by suction and by pressing the slurries between press  64  and belt  52 . 
     Other materials, such as seeds, chemical fertilizer or soil nutrients may be added during the manufacturing process. In the preferred embodiment, the additional materials will form a part of the initial fiber slurry  50  that is introduced onto belt  52 . However, these materials may be added with the second slurry  60  or, they may be added before slurry  60  has been introduced (as fiber slurry  50  is slowly becoming solidified). Of course, the materials may also be imbedded into the fiber mat  4  after collar  8  has been completely solidified (discussed below). 
     After a substantial portion of the water has been removed from slurries  50 ,  60  (preferably about 80 to 90%), belt  52  moves the mixture into an enclosed housing  66 . Within this housing  66 , the slurries are pressed between a draper chain  68  and belt  52 . In addition, slurries  50 ,  60  are heated by a heater  70  to further solidify and dry the mixture. The final semi-rigid product  72  then exits housing  66  and is cut into various shapes and sizes depending on the application, as discussed above. For example, hole  10  may be drilled through collar  8  and concave upper surface  12  may be formed by conventional techniques, e.g., contouring the ground surface. Alternatively, the semi-rigid product  72  may be formed into a large roll as it is discharged from belt  52 , instead of cutting the binder into discrete sizes and shapes. The roll can be used, for example, on large farms for planting a crop through the roll. 
     The fiber and the organic material, e.g., almond wood chips, are chopped into fine pieces by a chip cutter before they are mixed with the water to form the slurries. FIGS. 5-9 illustrate the preferred embodiment of a chip cutter  80  according to the present invention. As shown in FIGS. 5 and 7, chip cutter  80  includes an outer base assembly  82  that is made up of a plurality of threaded rods  85  extending through circumferentially spaced holes  86  in a number of annular spacer disks  88 . A number of pipes  84  are placed over the threaded rods  85  between holes  86  in disks  88  in a sequential manner. Pipes  84  are also preferably held to a drive assembly  106  on each end of outer assembly  82  with a conventional washer  91 . As shown in FIG. 6, drive assemblies  106  are connected to an axial shaft  102  through an end plate  103  with bolts extending through holes  103   a  in end plate  103  and tapped holes  102   a  in drive assembly  106 . 
     A plurality of cutting blade assemblies  90  are slidably and rotatably coupled to pipes  84 . As best shown in FIGS. 8 and 9, cutting blade assemblies  90  each include a blade  92  mounted to a hollow tube  94  via a mounting bracket  96  so that blade  92  is spaced from tube  94 . This allows blade  92  to rotate relative to outer assembly  82 , as discussed below. Blade  92  is preferably constructed of metal, such as high speed steel, and includes a base portion  93  and a sharpened tip  95  facing opposite tube  94 . Mounting bracket  96  is bonded, e.g., welded, to the outer surface of tube  94  and is preferably angled such that blade  92  extends in a substantially radial direction relative to tube  94 . Mounting bracket  96  and blade  92  each include a pair of holes  98  for receiving bolts  100  for connecting blade  92  to bracket  96 . Of course, the invention is not limited to this configuration and blade  92  may be mounted to tube  94  in a variety of conventional manners. 
     Referring again to FIGS. 5 and 7, tubes  94  are disposed around pipes  84  between spacer disks  88  so that cutting blade assemblies  90  are slidably and rotatably disposed about pipes  84 . In this manner, blades  92  will rotate slightly relative to base assembly  82  when base assembly  82  is rotated around the axis of shaft  102 . This provides flexibility to blades  92  during the cutting of chips, paper products, etc., as discussed below. The diameter of tubes  94  will be close enough to the outer diameter of pipes  84  such that rotation of base assembly  82  will effect a rotation of cutting blade assemblies  90 . In the preferred embodiment, chip cutter  80  will include between 5-100 cutting blade assemblies and more preferably about 50 cutting blade assemblies, extending circumferentially around the longitudinal axis of outer assembly  82  (see FIG.  7 ). Tubes  94  extend beyond mounting bracket  96  and cutting blades  92  to permit contact of tubes  94  against disc  88  while rotating around pipes  84 . Cutting blade assemblies  90  are mounted on alternating pipes  84  to allow room for each blade  92  to rotate without contacting an adjacent blade  92 . Preferably, about 1-24 cutting blade assemblies  90  will be disposed along each rod  25  (i.e., in the longitudinal direction, see FIG.  5 ). 
     It should be noted that the present invention is not limited to the above configuration for spacing cutting blade assemblies  90  from each other. For example, the blade assemblies may alternate in both the longitudinal and circumferential direction. In this configuration, all of the cutting assemblies would be disposed on pipes. However, they would alternate so that a cutting assembly will be disposed on every other pipe in the circumferential direction and offset between every other spacer disk in the longitudinal direction. 
     As shown in FIGS. 5 and 6, axle shaft  102  is coupled to a motor shaft (not shown) via a multiple belt pulley  104  for rotating base assembly  82  and cutting blades  92  therewith around the shaft axis  102 . A second drive assembly  83  is mounted on the opposite end of outer assembly  82 . In the preferred embodiment, outer assembly  82  includes a wheel hub  106  coupled to an axle  108  by a pair of roller bearings  110 . Axle  108  is, in turn, coupled to axle shaft  102  by an outer support bearing  112 . The axle, axle shaft and wheel hub can be specifically manufactured for chip cutter  80  or, alternatively, these pieces can be removed from a suitable existing axle, such as the rear drive axle of trucks. 
     To cut the fiber and almond wood chips, a motor (not shown) is energized so that multiple belt pulley  104  rotates axle shaft  102  at a suitable speed, preferably between 2000 to 4000 RPM. Axle shaft  102  rotates base assembly  82  and cutting blade assemblies  90  about the axis of shaft  102 . The fiber and almond wood chips are then fed into assembly  82  so that blades  92  chop them into fine pieces. 
     Although the foregoing invention has been described in detail for purposes of clarity of understanding, it will be obvious that certain modifications may be practiced within the scope of the appended claims. For example, flour or vegetable starch can be added to the second slurry to facilitate the binding of the two slurries together. Alternatively, a fire retardant, such as clay, can be used as a binding agent. In this configuration, the collar would be additionally useful as a firebreak between fields.