Abstract:
A cross-linked, water absorbent polymer is mixed with desirable additives and coated to prevent water absorption to create a blend that is added to water injection systems for turf and soil maintenance. The coating is rinsed off the water absorbent polymer resulting in expansion of the polymer into a gel-like substance. The water absorbent polymer has the ability to retain water and nutrients in the soil preventing nutrient runoff and reducing watering frequency. Injection of the water absorbent polymer directly into soil reduces waste and reduces hazard caused by slippery material left on soil surfaces. The method and system for mixing and injection into soil is disclosed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Patent Application No. 62/103,827 filed on Jan. 15, 2015 which is incorporated by reference as if fully set forth, and this application is a continuation-in-part of U.S. patent application Ser. No. 14/605,261, filed Jan. 26, 2015, which claims the benefit of U.S. Patent Application No. 61/931,448 filed on Jan. 24, 2014, which applications are incorporated by reference as if fully set forth. 
    
    
     FIELD OF INVENTION 
     This application generally relates to the field of turf maintenance, ornamental horticulture, nursery growers, agriculture and more specifically, to the application of liquid polymer additives with precision and thorough distribution to a targeted area in soil without disruption or disturbance to the ground surface. 
     BACKGROUND 
     Turf and soil maintenance, for those involved in the golfing industry ornamental horticulture, nursery growers, agriculture and turf grass management, plays a critical role in the success of a business. The greens and fairways provide the surface where golfers spend the majority of their time. Proper treatment and maintenance of that surface creates a higher quality product, and provides for a more aesthetically appealing landscape, which creates a highly attractive and desirable course for play. 
     The introduction of various materials, such as soil amendments, fertilizers, insecticides, and aeration improves the properties of the soil and the growth it supports. Conventionally, farmers and turf maintenance people have, for the most part, incorporated substances such as fertilizers, insecticides and polymers into the soil using tillage tools that mechanically cut through the ground and release the additive products at a point below the top surface of the ground. Surface treatment may also be carried out by either spraying liquid chemicals onto the top surface of the ground or spreading dry materials on the surface without making efforts to incorporate them deeper into the soil. However, top surface application of chemicals results in the presence of excess material left on the surface leading to several undesirable side effects, such as a slip and fall hazard, excess moisture on the surface, wasted material, and environmental impairment due to run off and exposure to wild life. 
     While a significant amount of technology currently exists for placing liquid substances into the subsurface using high pressure water jets that cut through the soil and carry the substance down to the desired depth, very little successful work has been done in the application of liquid additives with precision and thorough distribution in the root zone. Accordingly, there exists a need for an additive that can be delivered precisely and thoroughly to the root zone that distributes nutrients while reducing the necessity for frequent watering and soil treatments. 
     SUMMARY 
     A cross-linked, water absorbent polymer is mixed with desirable additives and coated to prevent water absorption to create a blend that is added to water injection systems for turf and soil maintenance. The coating is rinsed off the water absorbent polymer resulting in expansion of the polymer into a gel-like substance. The water absorbent polymer has the ability to retain water and nutrients in the soil preventing nutrient runoff and reducing watering frequency. Injection of the water absorbent polymer directly into soil reduces waste and reduces hazard caused by slippery material left on soil surfaces. The method and system for mixing and injection into soil is disclosed. 
     A peristaltic pump injection system used in turf maintenance equipment for placing additives, such as liquid materials, into the soil at a precision depth is disclosed. Fluid jets, for example using water or air blasts, carry the materials through the peristaltic pump injection system and into the soil and leave no eruption on the surface to interfere with any immediately following activities or other treatments. This is particularly beneficial where the materials are being added to lawns, putting greens and fairways on golf courses, sports fields and the like. 
     The additives delivered in a blast can be used to effectively drill a hole in the soil. The hole may have a diameter in the range of 0.1 to 2.0 inches. Substantially simultaneously, the created hole may be filled with a soil additive or amendment. Once the hole has been filled, the surface of the soil is left smooth, with minimal soil disruption and displacement. 
     The additives are injected into the injection manifold through an upstream valve and high pressure water is injected through a poppet valve assembly, downstream of the valve where the additive materials are injected. The additives include a blended water absorbent polymer coated with an agent to retard absorption of water. The water absorbent polymer is cross-linked potassium polyacrylate. The dry size of the water absorbent polymer is approximately 200-800 microns. The agent to retard absorption of water is rinsed off the water absorbent polymer after contact with water in soil. The polymer blend comprises fertilizers. The polymer blend comprises salts 
     The fluid/additives are injected between high pressure blasts into the injection manifold and are mixed in the injection manifold with the high pressure water. In some instances, the fluid/additives may be injected into the dosing material. This results in injected materials that are not damaged by high pressure and allows for complete defusing of the additives into the soil. This mixture is urged through tubes of the peristaltic pump assemblies, at a precision amount, to nozzles and manifolds of the device. 
     The device fires its nozzles as a function of the distance traveled by the device along its path of travel, e.g. as ground speed sensed over a period of time. A ground speed sensor generates a signal that is calculated as a ground speed by the central controller and used to calculate the distance traveled, or the instantaneous speed. The central controller can adjust the injector rates for the peristaltic pumps, on the go, and for systems using multiple peristaltic pumps, the pumps can be adjusted both individually and together. 
     Thus, until the device travels its pre-set distance, the next blast from the nozzles may not occur, regardless of whether the device travels quickly or slowly over such distance. In other words, although the spacing between holes may be adjusted by the operator, once a selection is made, that spacing from the beginning of the hole to the beginning of the next hole, remains substantially fixed. 
     The device may provide deep penetration of additives into the soil, as great as 10 inches in depth and be used to punch through sod. The device may also punch through fiber or stabilized sports turf to allow better root proliferation below a mesh; aerate, amend, and top-dress in one pass, and allow for play on a smooth surface in approximately one hour. 
     For sake of brevity, this summary does not list all aspects of the present invention, which is described in further detailed below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of the preferred embodiments, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements shown. 
         FIG. 1A  is a schematic view of a system for injecting an additive into the soil in accordance with a disclosed embodiment. 
         FIG. 1B  is a diagrammatic view of the reservoir of  FIG. 1A  including an additive with a polymer. 
         FIG. 2  is a perspective view of a rotating carriage with an encoder disc in accordance with a disclosed embodiment. 
         FIG. 3  is a schematic side view of the system of  FIG. 1A  on a movable platform in accordance with a disclosed embodiment. 
         FIG. 4  is a flow diagram if a method in accordance with a disclosed embodiment. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common in the figures. The figures are not drawn to scale and may be simplified for clarity. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
     While described in reference to a system for injecting liquid additives to soil, the present invention may be modified for a variety of applications while remaining within the spirit and scope of the claimed invention, since the range of the potential applications is great, and because it is intended that the present invention be adaptable to many such variations. For example, the system could be used for application if stabilizers to a ground cover other than soil, for example asphalt or macadam. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Certain terminology is used in the following description for convenience only and is not limiting. The words “front,” “back,” “forward,” “backwards,” “inner,” and “outer” designate directions in the drawings to which reference is made. Additionally, the terms “a” and “one” are defined as including one or more of the referenced item unless specifically noted otherwise. A reference to a list of items that are cited as “at least one of a, b, or c” (where a, b, and c represent the items being listed) means any single one of the items a, b, or c, or combinations thereof. A recitation of “into the soil” or the like means to the surface of the soil as well as beneath the surface of the soil unless the context clearly indicated otherwise. The terminology includes the words specifically noted above, derivatives thereof, and words of similar import. 
     In an example, soil injection systems, such as those detailed in U.S. Pat. No. 5,605,105 and U.S. Pat. No. 7,581,684, both of which are incorporated herein by reference as if fully set forth, are used to inject the water absorbent polymer into the soil. This method of injecting the polymer into the soil results in thorough and precise distribution with the added benefit of little surface disruption. The high pressure water from the injection system may begin or even complete the process of washing off the protective coating from the polymer for more rapid polymer expansion into the gel-like absorbent substance in the soil. 
     One method and device for inserting the present polymer gel into the soil is described in detail below. Many other methods of insertion may be used including numerous off the shelf techniques for applying chemicals and products to the root zone of grass of other plants, by way of example. 
       FIG. 1A  schematically shows an example of a system  100  for injecting a polymer into the soil including a peristaltic pump assembly  102 . The peristaltic pump assembly  102  is configured for placing material on or beneath the surface S of a soil system or soil. The device delivers wet material at least to the surface S of the soil and preferably into the soil subsurface to a desired depth D. The peristaltic pump assembly  102  is generally known to include a plurality of rollers  103  supported rotation on a rotating carriage assembly  104 . As the carriage  104  rotates as indicated by arrow  105  under the influence of a variable voltage motor  208  ( FIGS. 1 and 2 ), rollers  103  successively compress a resilient tube  106  to urge a material within the tube  106  in the direction of rotation (i.e., corresponding with arrow  105 ). An axial face of the rotating carriage assembly  104  may include an encoder disc  202 . The encoder disc  202  has features  204 , for example holes  204 , formed around a perimeter of the disc  202  as illustrated in  FIG. 2 . A sensor  206  ( FIG. 1A ) is positioned to read, or sense, data from the encoder disc  202 , for example the number of features  204  passing in a given period of time, and provide that data to a computer control system or controller  108 . 
     A first end  106   a  of the resilient tube  106  is fluidly coupled to an additive reservoir  110  containing an additive  111 . The first end  106   a  resilient tube  106  may be directly coupled to the reservoir  110  or may have one or more intermediate fluid conduits forming inlet line  124 . The additive reservoir  110  contains a liquid additive  111  that may comprise one or more miscible or immiscible liquids or one or more solids suspended in one or more liquids, as in a slurry, or other fluid compositions, such as a gel, suitable for pumping via a peristaltic pump. 
     Referring now additionally to  FIG. 1B .  FIG. 1B  is a diagrammatic view of the reservoir  110  of  FIG. 1A  including an additive  111  with a polymer  150 . Additive  111  may include a polymer  150 . 
     Polymer  150  may include cross-linked polymers  150   a ,  150   b ,  150   c ,  150   d ,  150   e  and food grade emulsifiers, stabilizers, preservatives, and growth enhancers. Polymer  150  may be formulated into a liquid flowable form with a blend of agents  160  to short-term retard the expansion of polymer  150 . A cross-link is a bond that links one polymer chain to another. The polymer chain may be linked via covalent bonds or ionic bonds. Polymer  150  may be a synthetic polymer or natural polymer, such as a protein, for example. Generally, cross-linking promotes a difference in the polymers&#39; physical properties. 
     Once in the soil, the expansion of polymer  150  may be retarded until coating  160  is completely washed off as a result of precipitation or irrigation. The expanded polymer  150  may reduce watering frequency by increasing moisture infiltration rates and the capacity of the soil to retain water. This in turn decreases water runoff due to the hydrophilic nature of polymer  150 . The presence of the water absorbent polymer  150  helps to moderate soil temperature and makes aeration more effective. Yet another benefit of the disclosed polymer  150  is a greener, fuller top growth and higher crop yields and water savings when the polymer  150  is used in farm soil. 
     An embodiment may provide a method for injection of polymer  150  directly into the soil at the root zone as described herein. This method results in excellent distribution of nutrients, prevents disruption of turf surface, and eliminates excess material from turf surface. The direct injection of the water absorbent polymer  150  directly into the soil profile also has the advantage of improving root growth and viability. 
     In one embodiment of the disclosure, polymer  150  includes a coating  160  that is a vegetable oil to prevent polymer  150  from absorbing and expanding prior to injection in soil. Polymer  150  may contain additives, such as fertilizers, which help to retain nutrients in the soil profile thereby reducing nutrient leaching. 
     A blend of agents  160  will retard the expansion of a water absorbent polymer  150  until after polymer  150  has been delivered to the target area in soil. For example, polymer  150  may be a cross-linked potassium polyacrylate polymer that is blended with the desired additives, such as food grade emulsifiers, stabilizers, preservatives and growth enhancers. Polymer  150  may be coated, such as with vegetable oil and proprietary formula which forms a protective coating  160  that retards the ability of polymer  150  to absorb water, thus delaying expansion of polymer  150  into a gel-like substance. The coated polymer  150  may be formulated into a liquid for injection into soil as set forth herein. Once polymer  150  has been injected into the soil, the protective coating  160  may be washed off either by the process of placing polymer  150  into the soil, after some precipitation or irrigation or a combination thereof, enabling polymer  150  to absorb water and swell to full capacity in the root zone. 
     In an embodiment, larger particle sizes  150   a  may be used to decrease the rate of degradation of the particles  150   a ,  150   b ,  150   c ,  150   d ,  150   e  and prevent consumption by microbes, which consume or otherwise breakdown smaller polymer particles  150   e  more quickly. 
     In an embodiment, the dry polymer  150  particles are 200-800 microns in size to reduce degradation rates. A larger particle  150   a  size is also desirable because larger particles may absorb more water, resulting in greater and longer lasting benefit to the soil. Microbes present in the soil consume the particles  150  and do so more quickly with the smaller particles  150   e  reducing the benefit to the soil. Accordingly, the larger particle size  150   a  may provide a benefit to compensate for microbial activity and extend particle presence in soil. 
     A second end  106   b  of the resilient tube  106  is fluidly coupled to the manifold  112  either directly or through one or more intermediate fluid conduits forming outlet line  126 . A check valve  120  is placed in the outlet line  126  between the peristaltic pump  102  and the manifold  112 . The check valve  120  is configured to allow flow from the peristaltic pump  102  to the manifold  112  but to prevent or block flow from the manifold to the peristaltic pump  102 . The peristaltic pump is controlled to constantly provide an amount of additive to the manifold  112 , except for during an injection, discussed below. As the additive  111  flows into the manifold  112 , the pressure within the manifold is at or near atmospheric pressure (i.e., 0 pounds per square inch gage) allowing a free flow of the additive. In an example as illustrated, the second end  106   b  of the resilient tube  106  is coupled with the manifold at a midpoint L/2 of the length L of the manifold via outlet line  126 . 
     The manifold  112  includes a plurality of nozzles  114 . In the non-limiting embodiment illustrated schematically in  FIG. 1A , eight nozzles  114  are shown evenly spaced along the length L, although spacing need not be even. In other embodiments, a greater or lesser number of nozzles  114  may be used with even or uneven spacing. The nozzles  114  are in direct fluid communication with the interior of the manifold  112  as illustrated. In an example, one or more nozzles  114  may have a valved connection with the manifold  112 . 
     A source of pressurized fluid  116  is in fluid communication with the manifold  112  via pressure line  128 . In an example, the point of attachment between the manifold  112  and the source of pressurized fluid  116  is at a midpoint L/2 of the length L of the manifold  112  via pressure line  128 . In an example, the source of pressurized fluid  116  is attached to the manifold  112  adjacent to the second end of the resilient tube  106 . 
     The source of pressurized fluid  116  may be an accumulator or other device or structure configured to supply a fluid  117  at a substantially constant pressure. As used herein, a pressurized fluid  117  is a fluid at a pressure greater than the surrounding atmospheric pressure. This pressure is sometimes referred to a gage pressure to distinguish it from the total, or absolute, pressure which includes atmospheric pressure. In some embodiments, the pressurized fluid  117  may be at a pressure of up to 4,000 pounds per square inch, for example the pressure of the pressurized fluid  117  may range from about 2,000 pounds per square inch to about 4,000 pounds per square inch. 
     A valve, for example a poppet valve  118 , is placed in the pressure line  128  between the source of pressurized fluid  116  and the manifold  112 , preferably adjacent to the manifold  112 . The poppet valve  118  is configured to provide a blast or a jet of pressurized fluid  117  to the manifold. Advantageously, the blast or jet of pressurized fluid  117  interacts with the additive  111  delivered to the manifold by the second end of the resilient tube  106   b . The interaction of the pressurized fluid  117  and the additive  111  in the manifold evenly, or substantially evenly disperses the additive  111  in the pressurized fluid  117 . 
     The (gage) pressure within the manifold  112  varies from atmospheric pressure to approximately the pressure of the pressurized fluid source  116 . Accordingly, a check valve is not included, as the contents of the manifold will not flow in the direction of the pressurized fluid source  116 . However, a check valve may be placed in the pressure line to insure the contents of the manifold do not enter the high pressure source  116 . 
     In an example, a hopper  132  containing a dry filler material  134  may be coupled via line  136  to the nozzles  114  (only shown connected to one nozzle  114  in  FIG. 1A  for clarity). As the injected material travels through the nozzles  114 , the velocity of flow causes a vacuum in the nozzles  114  behind the flow. This vacuum can be used to draw the dry material  134  into the nozzle  114  and flow into any void caused in the soil surface S A sensor  308  may be attached to a wheel  306 , either free-wheel or drive wheel, for selectively sensing data corresponding to ground speed. In an example, the data relates to angular displacement corresponding to rotations of a wheel  306  of a known diameter. Between the sensor  308  and the controller  108  is a communication link  310  to facilitate communication of ground speed data between the sensor  308  and the controller  108 . 
     In the non-limiting embodiment illustrated in  FIG. 3 , the entire system  100  is supported on the platform  302  for ease of illustration only. Some components may be supported for movement over the surface S in a separate vehicle. The communication link  310  may be a wired link, or may be a wireless link connection. 
     When the output motor  208  rotates the carriage assembly  104 , rollers  103  compress the resilient tube  106  within a cavity peristaltic pump  102  to draw the additive  111  from the additive reservoir  110  through the first end portion  106   a  and force the additive  111  through the second end  106   b  of the resilient tube. In an example, the he carriage assembly  104  can rotate in a clockwise (as illustrated) or counter-clockwise direction and additives in the resilient tube  106  can be urged within the flexible tube in the direction of travel of the rollers  103  (i.e., corresponding with arrow  105  in  FIG. 1A ). 
     The additives  111  are provided or metered out by the peristaltic pump  102  in precision amounts to the injection manifold  112 . This is accomplished by mounting an encoder disc  202  on the carriage assembly  104  ( FIG. 2 ). The encoder disc  202  may be formed from a metal, for example stainless steel, with features, such as holes  204  that are sensed by a sensor  206 , for example a Hall Effect proximity sensor. As shown in  FIG. 2 , the sensor  206 , for example a proximity sensor, is mounted to the peristaltic pump housing and detects the absence or presence of metal directly in front of it. In an example the proximity sensor  50  reads the revolutions of the encoder disc  202  per a period of time and reports the revolutions to a computer control system, controller  108  via communication link  130 . The communication link  130  may be a wired link or a wireless link to facilitate transmission of at least a control signal from the controller  108  to the motor  208 . As illustrated in the non-limiting embodiment of  FIG. 4 , each through hole  204  in the encoder disc  202  represents 1/40 of the peristaltic pump&#39;s  102  volume per 1 revolution. For example, if the peristaltic pump&#39;s  102  volume per revolution is 0.16 ounces, each hole would be equal to 0.0036 ounce. As illustrated in  FIG. 1A , the computer sends a control signal, for example a variable output voltage, to the motor  208  to pump the additive material  111  at a given revolution per period of time. In other words, the controller  108  controls the amount of material that is output from the peristaltic pump  102 . The desired amount of material output can be pre-set at the controller  108  and may vary from approximately 3 oz. per 1,000 sq. ft. to approximately 365 oz. per 1,000 sq. ft. The peristaltic pump  102  output is controlled by the controller  108  based on data provided by the sensor  206  and the sensor  308 . The sensor  308  provides ground speed data to central controller  108 . 
     As shown in  FIG. 1A , the additives  111  of the peristaltic pump  102  are provided to the injection manifold  112  through valve, check valve  120 , and high pressure fluid, for example water, is injected through a poppet valve assembly  118 , adjacent to the valve  120  where the additive materials  111  of the peristaltic pump  102  are provided. When high pressure fluid (e.g., water) is injected into the injection manifold  112 , the injection causes the pressure in the manifold  112  to rise. The pressure in the manifold  112  can rise to the same, or substantially the same, pressure as the pressurized fluid source  116 . This increase in pressure closes the check valve  120  that allows the additive  111  to flow into the manifold. The pressure within the manifold  112  causes the fluid  117  and the additive  111 , mixed under the influence of the fluid  117  jet in the manifold  112 , to exit the manifold through the nozzles  114 . The nozzles  114  may be in free and open fluid communication with the atmosphere as illustrated, or may include one or more valves to restrict the flow out of the manifold  112 . 
     As the pressure drops in the manifold  112 , the check valve moves into an open position and the additives  111  again enter the mixing chamber. Injection of the high pressure fluid  117  into the injection manifold  112  stops the movement of the additive into the injection manifold for duration of approximately 0.05 to 0.30 seconds. During this time period, the pressure in the mixing chamber increases from approximately 0 p.s.i. (gage, therefore corresponding to atmospheric pressure) to approximately 4,000 p.s.i. (gage). After each injection of high pressure fluid  117  into the manifold  112 , the pressure in the manifold  112  decreases to approximately 0 p.s.i.; during this period, between high pressure injections, the additives move into the injection manifold  112 . The mixture of additives and high pressure water is pumped into the soil as noted below. 
     During the period when the check valve  120  is closed and the pressure in the manifold  112  is elevated, the carriage assembly  104  of peristaltic pump  102  continues to turn as controlled by the variable voltage motor  208 . The second end portion  106   b  of the resilient tube  106  or the outlet line  126 , or both the resilient tube  106  and the outlet line  126 , acts as an accumulator for the additive materials  111  pumped during that time period. 
     The mixture of additives  111  and high pressure fluid  117  is injected into the ground G under high pressure through nozzles  114 . The velocity of the high pressure fluid  117  moving through the nozzles  114  allows the mixture to be forced into the soil profile from depths D of approximately 1 to 12 inches. Movement of the high pressure fluid  117  and mixture into the soil creates fractures in the soil. The mixture is then drawn into micro pores in the soil through capillary action. 
       FIG. 4  is a flow diagram representing a method  400  for injecting an additive to the soil according to a disclosed embodiment. At  402  data related to ground speed of the system  100  is sensed by a sensor, for example sensor  308 , which may include an encoder disc mounted to a wheel  306  and a proximity sensor fixed to the movable platform  302 . The data is communicated to the controller  108  where the data may be stored. 
     At  404 , the ground speed of the system  100  including at least the manifold  112  and nozzles  114  is calculated at the controller  108  from the data received. 
     At  406 , an area per unit time covered by the nozzle assembly  114  at the calculated ground speed is calculated at the controller  108 . 
     The controller  108  determines at  408  the amount of additive  111  required at the nozzles  114  in order to apply a predetermined amount of additive per unit area to the soil. 
     At  410 , the controller  108  provides a control signal, for example a variable voltage, via the communications link  130  to the peristaltic pump  102  to deliver the determined amount of an additive  111  to the manifold  112 . Under the pressure generated by the peristaltic pump  102  in outlet line  106   b , the check valve  120  is caused to open, allowing the determined amount of additive  111  to be delivered to the manifold  112 . 
     At  412 , poppet valve  118  opens and a pressurized fluid  117  is introduced to the manifold  112 . As the pressurized fluid  117  enters the manifold, the check valve  120  is urged to close and the manifold become pressurized to the same, or substantially the same, pressure as the pressurized fluid  117 . The pressurized fluid  117  enters the manifold  112  as a jet or a blast and distributed the additive within the manifold  112 . 
     At  414 , the pressurized manifold forces the mixture of pressurized fluid and additive through the nozzles  114  and injects the mixture of pressurized fluid and additive into the soil. The sequence can be repeated for a set number of cycles programmed into the controller  108 . 
     Having thus described various methods, configurations, and features in detail, it is to be appreciated and will be apparent to those skilled in the art that many physical changes, only a few of which are exemplified in the detailed description above, could be made in the apparatus and method without altering the inventive concepts and principles embodied therein. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore to be embraced therein.