US20070269275A1

US20070269275A1 - Erosion control system and method of manufacturing same

Info

Publication number: US20070269275A1
Application number: US11/634,317
Authority: US
Inventors: Mark Kimberlin
Original assignee: Greenfix America
Current assignee: Greenfix America
Priority date: 2001-02-06
Filing date: 2006-12-04
Publication date: 2007-11-22

Abstract

An erosion control system is provided which generally includes a flexible composite blanket or matting including a core layer formed of rice straw. In addition, the present invention provides a green pigmented rice straw fiber blanket and methods for making same.

Description

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 10/894,641 filed on Jul. 20, 2004 which claims the benefit of U.S. provisional patent application No. 60/489,256 filed on Jul. 22, 2003 and which is a continuation-in-part of U.S. patent application Ser. No. 10/072,149 filed on Feb. 6, 2002, which claims the benefit of U.S. provisional patent application No. 60/266,782 filed on Feb. 6, 2001, the entire disclosure of each of which being incorporated herein by this reference.

BACKGROUND OF THE INVENTION

The present invention generally relates to erosion control, and more specifically relates to temporary or permanent turf reinforcement and soil retention matting or blankets.
Erosion control is an essential environmental consideration when new slope embankments and channels are created, for example during construction of buildings and drainage systems. Traditionally, newly constructed channels have been lined with concrete or rock to provide a hard, armor-like channel lining. Alternatively, the development of root reinforcement systems is relied upon to control erosion. Thus, methods have been developed for stabilizing soil on channel linings and other erosion prone surfaces by encouraging the growth of native or introduced vegetation along the surface. Ideally, a mature root system within the sloped surface functions to bond together the channel surface and inhibit soil loss during rains and other stresses.
However, embankment and channel surfaces often require reinforcement, particularly during the pre-vegetated stage and early stages of plant growth, to prevent loss of soil, seeds, seedlings and other small plants when the soil is in an unstable state.
Various reinforcement systems have been developed. For example, U.S. Pat. No. 5,849,645 to Lancaster, which is incorporated herein by this specific reference, discloses reinforced composite matting including a fiber matrix secured together by an arrangement of multiple nettings. The nettings form a series of alternating troughs and ridges, from between one eight an inch in height to one inch in height, along the matting. This three dimensional, “cuspated” aspect of the Lancaster matting is designed to trap mulch, sediment, and plant seeds in the troughs during early stages of plant growth. According to Lancaster, the trapped soil and other debris provide a growing medium for sprouting plants. Although the Lancaster patent recognizes the problems associated with erosion on new channel surfaces, the matting system disclosed does not address other problems, for example, high shear stress on the matting, particularly during long duration, high velocity water flow during the critical pre-vegetated stage. Furthermore, the Lancaster system requires that the matting be placed in a specific alignment with respect to channel flow. More particularly, Lancaster discloses that in order for the matting to trap sediment between the troughs and ridges, the matting is to be installed such that the troughs and ridges are perpendicular to the intended direction of channel flow. This requirement poses potential installation problems and setbacks.
Conventional prior art erosion control blankets have utilized wheat straw, coconut fiber, chopped or crimped synthetic polypropylene fibers or a blend thereof. Wheat straw, in particular, has long been an industry standard. Erosion control blankets made primarily of wheat straw suffer a number of disadvantages. For example, the natural decomposition process of wheat straw tends to extract nitrogen and other plant nutrients from the soil surface to which the straw is applied, thus detrimentally affecting soil fertility. Plants and seedlings growing from the surface and through the wheat straw-based covering does not promote the optimal growth of plant roots, thus delaying or hindering the goal of soil stability. To counteract this effect, fertilizers and other such additives are oftentimes incorporated into the blanket material in an effort to maintain or boost soil fertility during the early stages of plant growth.
Traditional wheat straw erosion control blankets are often relied upon for covering bare soil around a newly constructed home or other building prior to the establishment of landscaping. Unfortunately, these traditional erosion control blankets are aesthetically unappealing and are usually removed and discarded prior to mature landscaping being established, thus leaving the property in an unprotected state open to potential discharge of pollutants, which, in some jurisdictions, is a violation of state water quality regulations.
It will be appreciated by those of skill in the art, that the objectives of the present invention, for example, greater soil stability and establishment of foliage and a healthy root system, are essentially the same objectives to which conventional erosion control blankets have generally been directed. However, conventional erosion control blanket designs have been inadequate, for example, during high velocity, long term, sustained water flow conditions, and even more so when said blankets have been installed to a non-vegetated, bare or seeded soil surface.
There is still a need for an effective, aesthetically appealing erosion control product and method that will address at least some, and preferably all of the problems of prior art products and techniques.
The present invention provides a more effective, more technically advanced system for controlling soil loss erosion on channel and embankment surfaces, particularly during the critical pre-vegetation stage and in areas exposed to severe conditions of continuous, extended, high velocity water flows, and high shear stress erosion.
Another well known, related problem is a lack of an effective technique and/or product useful for covering and protecting newly developed land, for example, adjacent nearby newly constructed homes and the like. Traditional wheat straw environmental control blankets are highly unattractive to new homeowners and are therefore usually removed and discarded prior to the establishment of mature landscaping, This leaves the land in an unprotected state. Unfortunately, this practice is not considered environmentally acceptable, and is in some jurisdictions unlawful, in that it potentially opens adjacent properties to receiving runoff and potential discharge of pollutants.
The present invention also provides cleaner, substantially naturally weed free, more aesthetically appealing, more landscape friendly, more effective erosion control systems, relative to conventional erosion control products, and methods for protecting surfaces on newly developed land, for example, adjacent homes and office buildings, prior to and during the establishment of landscaping.

SUMMARY OF THE INVENTION

Accordingly, an erosion control system is provided, which generally comprises a flexible matting adapted to be secured to or placed on a surface, for example a substantially non-vegetated surface.
In one particularly useful embodiment of the invention, the system comprises a erosion control matting structured to substantially prevent soil loss on a substantially unvegetated and/or sloped surface, even when the matting is exposed to high velocity and/or long duration hydraulic events.
More particularly, this embodiment of the invention generally comprises a core layer formed of a fiber matrix comprising randomly oriented fibers, and a upper layer, bonded or secured to the core layer, wherein the core layer and the upper layer define a substantially flat upper surface. A flat upper surface is more specifically defined herein as a surface being without substantial three-dimensional features such as cuspations, pockets, ridges, or the like. Advantageously, the matting of this embodiment of the present invention has a substantially higher mass unit density in comparison to conventional erosion control mats. Specifically, the matting has a mass unit density of at least about 0.5 pounds per square yard and more preferably at least about 0.7 pounds per square yard (dry weight).
In one embodiment of the invention, the fiber matrix core preferably comprises a material selected from the group consisting of coconut fibers, flax fiber, polypropylene fibers, for example chopped polypropylene fibers, and combinations thereof.
The upper surface of the matting, in accordance with one embodiment of the present invention, preferably has a Manning's “N” value of roughness of less than about 0.044, and preferably has a roughness value of about 0.026 or less.
Advantageously, it has been found that during a storm event, the present system more effectively resists high shear stresses, such that high velocity liquid flow passes over the upper surface of the matting without substantially removing any of the soil beneath the matting. It is noted and will be appreciated by those of skill in the art, that conventional matting systems have typically been designed with substantial three dimensional features, primarily as a means of trapping soil during water flow over the surface of the matting. Although not wishing to be bound by any particular theory of operation, it is believed that the relatively flatter structure of the matting in accordance with the present invention contributes to the system being able to withstand higher flow velocities, by decreasing the high shear stress forces created, for example, by an increasing water depth flowing over a relatively rough surface.
In another particularly advantageous embodiment of the invention, an erosion control system is provided, comprising a flexible matting effective in controlling erosion and structured to be secured or placed on a surface prone to erosion, the matting including a substantially uniform core layer formed of rice straw fibers, for example, fibers of California Rice Straw.
For example, in an especially advantageous embodiment of the present invention, an erosion control system is provided which generally comprises a flexible matting effective to control erosion, wherein the matting includes a core layer that is comprised substantially entirely of rice straw fibers, and the matting has a substantially higher aerial density relative to an identical flexible matting not formed of rice straw fibers.
In one embodiment of the invention, the matting comprises a core layer made substantially entirely of rice straw fibers. This embodiment of the invention is particularly beneficial to providing a substantially superior environment (relative to conventional erosion control matting) that enhances germination and growth of plants without robbing the plants of beneficial nutrients.
The present invention also provides methods for processing rice straw, and methods for manufacturing rice straw blankets. It is noted that prior to the development of the present inventive methods, bulk bales of rice straw have been extremely difficult, if not impossible, to process to process using standard erosion control blanket manufacturing equipment.
The methods of the present invention include the steps of pulling rice straw fibers, for example from a bulk bale of rice straw, using a mechanism structured to separate and/or pull fibers of rice straw from the bale to achieve long, thin, more easily manageable rice straw fibers. More particularly, the methods comprise the step of utilizing a plurality of high speed rotating blades to contact and draw fibers from the bale.
The method may further include the step of discharging the rice straw fibers onto high speed exit conveyors. The method of the present invention effectively transforms the bulk rice straw bale into a substantially continuous, even fiber pile that is capable of being used on a surface for controlling erosion on the surface. The even fiber pile is of a form that that can be readily processed and digested by conventional blanket manufacturing material handling systems.
The rice straw fiber pile may be mechanically stitched, bonded or otherwise reinforced to form a blanket. A reinforcement element such as a netting material may be located on at least one of an upper surface of the core layer and the bottom surface of the core layer. In other words, a reinforcement element may be stitched or bonded to at least one of the major surfaces of the core layer. Stitching of the matting may be accomplished by any suitable means, for example but not limited to by stitching the core layer at specific intervals, for example, but not limited to between about one inch and about two inches on centers to ensure substantial uniformity of the matting. Preferably, stitching is sewn with monofilament thread or twisted multifilament thread of a minimum of about 1,000 denier or greater.
In a particularly advantageous embodiment of the invention, a method for controlling erosion is provided, including the steps of applying debated rice straw fibers in a substantially continuous, even layer onto a surface prone to erosion and allowing the rice straw fibers to remain on the surface during growth of seedlings and mature plants.
In another especially advantageous embodiment of the invention, a pigmented erosion control blanket is provided. It has been discovered that rice straw can be successfully pigmented, in accordance with methods of the present invention to achieve an aesthetically pleasing, high quality erosion control matting. For example, the present invention provides a green pigmented erosion control matting that provides construction developers an aesthetically pleasing ground cover for application around newly constructed homes.
It is noted, and will be appreciated and known by those of skill in the art, that all trials and attempts to dye natural erosion control fiber blankets, for example blankets of wheat straw, have been largely unsuccessful.
The present invention therefore provides a pigmented erosion control blanket, for example a green pigmented erosion control blanket. More specifically, the present invention provides a pigmented rice straw erosion control blanket. This embodiment of the invention is especially useful as a visually appealing, substantially weed free ground cover that aids in preventing runoff of soil, for example on newly developed land.
In a related aspect of the invention, a method of dyeing or pigmenting rice straw is provided. For example, after the stitching process of the rice straw mat or blanket generally described hereinabove, the rice straw mat is then passed under a low pressure spray bar which applies an inventive pigment composition.
A pigment composition in accordance with the present invention, for tinting or coloring rice straw fibers, generally comprises an aqueous pigmentation composition comprising an aqueous mixture of a pigment component, a binder component and an effective amount of a wetting agent, or surfactant. For example, in accordance with one embodiment of the present invention, a pigment solution concentrate is provided that can be combined with a diluent such as water prior to being applied to rice straw fibers.
The pigment solution concentrate may comprise about one part pigment component, for example a latex polymer dispersion having a desired color, for example but not limited to pigment green, and about one part binder component, for example a polymer coating material, and a surfactant. This concentrate is mixed with water at a ratio of about one part concentrate to about 100 parts water to form the aqueous pigment composition.
In another embodiment of the present invention, an erosion control system is provided which generally comprises a flexible matting structured to be installed on a surface prone to erosion, the matting including a core layer formed of a fiber matrix comprising plant fibers that are effective in releasing beneficial nutrients to the sloped surface upon decomposition of the plant fibers over a period of time. The plant fibers of the core layer preferably have a nutrient content of at least about 0.6% potassium, about 1.25% nitrogen, and about 2.0% phosphate, based upon 100% dry matter. The fiber matrix is preferably substantially absent of wheat straw. Preferably, the fiber matrix core comprises Sudan Grass (Sorgum Sudanese).
The substantial benefits of this type of erosion control product, which differentiates itself from other products that are currently on the market, are as follows:

- 1. Fertilization: The biodegradable plant fiber matrix products that contain the minimum P, K, N percentages will promote and enhance germination naturally through the decomposition of plant biomass in the seedbed and substrate.
- 2. Turf Stage: The biodegradable plant fiber matrix material will continue to compliment the conventional nutrients but at a decreasing rate. The material will decompose through decomposition of plant biomass and eventually be non-effective after its life cycle ceases.

The enhanced Sudan Grass erosion control product is preferably comprised of the following components:

Phosphorus (P): about 0.60% by weight P205 (min) on 100% dry matter basis
Nitrogen (N): about 1.25%-about 2.25% by weight N based upon 100% dry matter basis
Potassium (K) about 2.0% by weight K20 (min) and 100% dry matter basis

The enhanced biodegradable plant fiber matrix material preferably has at least a minimum of the above PNK components on 100% dry matter basis. Advantageously, the bionutrients within the biodegradable plant fiber matrix material will compliment conventional nonorganic nutrients, also known as man made fertilizers. The decomposition of the plant biomass within the biodegradable plant fiber matrix material contributes to the fertility status over time. In addition, when applied to a soil surface, the present invention has been found to significantly increase the germination ratio relative to a bare seeded soil plot.
During the turf stage, the biodegradable plant fiber matrix material will continue to compliment the conventional nutrients but at a decreasing rate. The material will decompose through decomposition of plant biomass and will eventually become non-effective at the end of the decomposition stage.
Each and every feature described herein, and each and every combination of two or more such features is included within the scope of the invention provided that the features included in such combination are not mutually inconsistent.
The present invention and the objects and advantages thereof will be more clearly understood and appreciated with respect to the following Detailed Description, when considered in conjunction with the accompanying Drawings and Attachment A, attached hereto and hereby made a part hereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of an embodiment of the erosion control system of the present invention, comprising erosion control matting during installation of the matting to a non-vegetated, sloped soil surface to prevent soil erosion and for enhancing development of stabilizing vegetation on the sloped surface.
FIG. 2 shows an exploded view of a portion of the matting shown in FIG. 1.
FIG. 3 shows a cross sectional view of the matting shown in FIG. 1.
FIG. 4 shows a perspective view of an upper layer of the matting shown in FIG. 1.
FIG. 5 shows an exploded view of another embodiment of the present invention.
FIG. 6 shows an exploded view of yet another embodiment of the present invention.
FIG. 7 shows the embodiment of the invention shown in FIG. 1 as installed in an alternative application, particularly embankment stabilization.

DETAILED DESCRIPTION OF THE INVENTION

Turning to FIG. 1, an erosion control, surface reinforcement system, in accordance with the present invention, is shown generally at 10. The system 10 is shown during installation thereof to a surface that is prone to erosion, for example a sloped, bare earth newly constructed embankment surface 11. For example, the system is being installed on the sloped surface 11 that is prone to high velocity and/or high duration hydraulic events, in order to promote the eventual growth of stabilizing vegetation on the surface 11.
Turning now to FIGS. 2 and 3, the system 10 generally comprises a flexible composite blanket, or matting 12, adapted to be temporarily or permanently placed on or secured to the surface 11. The surface 11 may be, for example, a newly constructed embankment, channel, a level or sloped bare earth or seeded surface. As will be appreciated by those of skill in the art, the slope of a channel surface is typically between about 3 to about 7 grade. Severe slope embankment angles are typically defined as 1:1 (45 degrees) or steeper.
The matting 12 generally comprises a flexible core layer 14 defining a lower surface 14 a and a substantially flat upper surface 14 b. The matting 12 further comprises an upper layer 16, secured to the substantially flat upper surface 14 a of the core layer 14. The core layer 14 and the upper layer 16 define a substantially flat upper surface of the matting 12. In addition, the core layer 14 is preferably bonded between a bottom netting layer 18 a and a top netting layer 18 b. The netting layers 18 a and 18 b are preferably stitched together, compacting the core layer 16 therebetween, for example by means of a polypropylene monofilament thread 20.
In a preferred embodiment of the present invention, the matting 12 is structured to withstand continuous, as well as intermittent, liquid flow, for example, high velocity water flow, over the surface 13 on to which it is placed and/or secured. The matting 12 of the present invention is designed to have a lower profile and more flexible than conventional reinforcement matting while exhibiting superior, tensile strength properties. Particularly, the matting 12, particularly an upper surface profile thereof, has no substantial three dimensional features such as grooves, troughs, cuspations, crimping, or other open structured, three-dimensional features.
Unlike prior art erosion control blankets, the present system 10 is not designed to trap sediment carried in water flowing over the surface thereof, but instead is designed to allow flowing water/particulate matter to pass freely, and with relatively low turbulence over the matting 12, while preventing soil loss from beneath the matting.
The upper layer 16 of the matting is essentially two-dimensional, and is bonded to the flat upper surface 14 a of the core layer 14. The upper layer 16 overlies and substantially conforms to the flat surface profile of the fiber matrix layer 12.
In a preferred embodiment of the invention, the core layer 14 is formed of a flexible fiber matrix 22, preferably comprising randomly oriented, natural plant fibers, densely packed between the lower netting layer 18 a and the upper netting layer 18 b. In addition, the core layer 14 has a substantially uniform thickness, preferably at least about 0.3 inches, preferably in a range of between about 0.3 inches to about 0.5 inches, or in a range of between about 0.7 inches to about 1.0 inches. When confined by the netting structure 20, the core layer 12 forms a relatively dense, uniform layer without troughs, ridges or other similar contoured, open structured or three dimensional characteristics.
The matting 12 of the present invention preferably is constructed to have a unit density of at least about 0.5 pounds per square yard, and more preferably, at least about 0.7 pounds per square yard.
Advantageously, the system 10 of the present invention has been found to promote the development of a relatively warmer, more humid microclimate beneath the matting 12, which encourages plant growth and seed germination, in comparison to prior art erosion control blankets.
The fiber matrix 22 comprises a plurality of randomly oriented elongated fibers or strands, for example, natural plant fibers. Other embodiments of the invention may include synthetic fibers, and other suitable fiber materials that are commercially available. In the presently described high velocity/high duration hydraulic event matting 12 of the present invention, the fiber matrix 22 preferably comprises a material selected from the group consisting of coconut fiber, flax fiber, chopped polypropylene fibers and combinations thereof. Other suitable natural or synthetic materials, for example hemp fibers, wood fibers, or plant straw, may alternatively be used.
The top net 18 b and bottom net 18 a preferably comprise a lightweight, grid-like netting material fastened to the fiber matrix 22, for example by machine stitching, for example at 1.5 inch centers. Bonding of the top net 18 b and bottom net 18 a to the fiber matrix may additionally be reinforced with deposits of a suitable adhesive.
Importantly, the flexible, two dimensional upper layer 16 is positioned to overlie and preferably closely conform to the core layer 14 to define a substantially flat upper surface of the matting being without substantial three dimensional features.
The upper layer 16 preferably comprises a relatively heavy weight polypropylene net marketed or otherwise specified as “geo grid” as understood by those of skill in the art. In this particular embodiment, the upper layer 16 of the matting 12 preferably comprises a high tensile strength, biaxial geogrid, such as shown in greater detail in FIG. 4. The geogrid is preferably “permanent” in that it is substantially not photodegradable, and comprises, for example, PVC coated, knitted polypropylene strands 28. Preferably, the strands 28 have a spacing distance in a range of between about 0.2 inches to about 2.0 inches, and more preferably in a range of between about 0.4 inches to about 1.0 inches. As shown, the strands 28 define a substantially two-dimensional grid configuration, for example of uniform, rectangularly shaped apertures. Other suitable materials of construction may be employed in upper layer 16.
Still referring to FIG. 4, in this particular embodiment of the invention, the upper layer 16 includes a first set of substantially parallel strands arranged perpendicularly across a second set of substantially parallel strands. More specifically, the first set of strands comprises doubled strands 16 a, for example two strands arranged relatively close together in a side by side relationship. The second set of strands comprises twisted or helical strands 16 b having a helix-like outer surface or substantially helical outer surface. In combination, the first set of strands 16 a and the second set of strands 16 b define a substantially planar surface, without any substantial three dimensional features or surface topography. Although a square or rectangular grid is described and shown, it should be appreciated that other two-dimensional configurations are possible. The biaxial geogrid 16 serves in part as a confinement structural layer for the fiber core 12 to prevent rupture or tearing thereof, particularly during extreme hydraulic activity (high velocity/high shear applications).
During high velocity water flow, for example a flow of about 20 feet per second or greater, over an extended duration of time, for example of at least 50 hours or more, high shear stress forces are created. The matting 12 of the present invention has been found to have a superior capacity to withstand significantly greater shear stresses in comparison to conventional matting having higher roughness values.
Flatness, or roughness, of a surface, is a measurable quality. A degree of roughness of a surface is representable by a roughness coefficient known as Manning's “N” value. The Manning's “N” value of the present matting 12 is less than about 0.44, and more preferably is about 0.026. In addition to withstanding shear stress forces, the lack of three dimensional open spacing of the matting 12 preferably is effective to limit the amount of trapped soil and sediment which is desirable in many long duration, high flow applications.
Assembly and manufacture of the matting 12 in accordance with the present invention may be accomplished using conventional equipment and methods. For example, the fiber matrix 22 is mechanically stitch bonded between the netting layers, 18 a and 18 b. The layers of netting, i.e. 18 a and 18 b, and fiber matrix 22 are all overlaid with the upper layer 16, for example the biaxial geogrid material hereinabove described All of the layers are then stitch bonded on 1.5 inch centers with UV stabilized polypropylene monofilament thread 20 to form the reinforcement matting 12. Alternately, or in addition, the upper layer 16 can be adhered to the layers of netting 18 a and 18 b and fiber matrix 22. Any suitable, preferably water resistant, adhesive may be employed. A number of such adhesives are well known and/or commercially available.
The matting 12 is preferably secured to the channel surface (or other surface) by means of 8 inch (minimum size) U-shaped staples 34, shown in FIGS. 1 and 3. The staples 34 are set to intersect the machine stitching and cross the strands 28 of the upper layer 16. Other suitable means may be employed for fixing the matting 12 to the soil surface. Advantageously, the matting of the present invention is substantially more flexible than conventional erosion control blankets, allowing the matting 12 to more closely conform to the contour of the slope or embankment surface to which it is installed.
The erosion control system 10 of the present invention minimizes erosion of a channel bed and other erosion prone surfaces, particularly when such surfaces are subjected to continuous, high velocity flow conditions. Preferably, the matting is structured to withstand a liquid flow of between about 9.5 feet per second to about 20 feet per second for a duration of between about 30 minutes to a duration of about 50 hours. Soil loss associated with these velocities and shear values disclosed herein in accordance with the present invention, are about 0.18 inches per hour as measured by industry standard accepted erodible bed flume testing protocols and performance standards.

EXAMPLE

As a specific example, an erosion control system in accordance with the present invention comprises a fiber matrix core layer 14 of 100% coconut fiber and a permanent (non photodegradable) polypropylene biaxial geogrid upper surface 16. The matting is further reinforced with an upper net 18 a and bottom net 18 b and a monofilament thread having a strength of at least about 1000 denier. The matting 12 in accordance with this specific example has a weight of about 0.95 pounds per square yard, a thickness of at least about 0.32 inches. Despite the In addition, the matting has a tensile strength of up to about 172.6 pounds per square foot, and an elongation of up to about 18.1 percent and a Manning's “N” value of about 0.026. It is noted that these parameters (tensile strength, elongation) are significantly higher than conventional erosion control blankets having a similar flexibility. When said matting 12 is placed on or secured to a severely sloped, unvegetated channel surface, the matting 12 withstands continuous high velocity flows of up about 18 feet per second for storm event durations of up to about 50 hours or more, including peak flows of up to 20 feet per second for short durations of up to about two hours.
Turning now to FIG. 5, another embodiment of the invention is shown generally at 110 (with like features being identified with like reference numerals increased by 100). The system 110 generally comprises a flexible matting 112 structured to be placed on or secured to a surface prone to erosion, the matting 112 including a core layer 114 formed of a fiber matrix 122 comprising randomly oriented plant fibers, wherein the plant fibers are effective in releasing effective amounts of beneficial nutrients to the surface upon decomposition of the plant fibers.
Preferably, the plant fiber matrix 122 has a nutrient content of at least about 0.6% potassium, about 1.25% nitrogen, and about 2.0% phosphate, based upon 100% dry matter, and is substantially absent of wheat straw, which is known to draw and nutrients from a soil surface upon decomposition of the wheat straw. Even more preferably, in this embodiment of the invention, the fiber matrix 122 comprises Sorgum Sudanese, i.e. Sudan straw, or Sudan grass.
During development of the present invention, Sudan grass was found to contain the highest amount of proteins and nutrients available to the soil upon decomposition thereof, including nitrogen, phosphorous, potassium, magnesium, calcium and zinc, in comparison to other plant fibers such as hemp, wood, and coconut. The three components of nitrogen, phosphorous and potassium are considered as macronutrients for sustaining plant growth and development.
Although FIG. 5 shows netting layers 18 a and 18 b and upper layer 16, it is noted that these features are not necessary and any suitable bonding means may be utilized in lieu thereof.
In an especially advantageous embodiment of the invention, shown in FIG. 6, an erosion control system 210 is provided comprising a flexible matting 212 structured to be placed on or secured to a surface prone to erosion.
The matting 212 comprises a core layer formed of a matrix 214 of randomly oriented rice straw fibers, preferably California rice straw. The system 210 may further comprise a reinforcement mechanism 18 a and/or 18 b, for securing the fibers of the matting in a substantially uniform layer.
Rice straw is available as a byproduct of the agricultural rice industry. This embodiment of the invention advantageously provides a naturally weed free, durable matting 212 that is superior in controlling erosion relative to conventional erosion control products. It has been discovered that the rice straw matting of the present invention effectively promotes germination of seedlings and healthy growth of vegetation. Rice straw provides a high cover factor, or aerial density and has a high silica content. The structure of the rice straw matting of the present invention has an aerial density that is increased relative to identical matting not made of rice straw. This high aerial density (a term that is well known and understood in the art) effectively protects the seed bed and soil from becoming displaced during a rain event. The matting is structured to permitting a sufficient amount of light to penetrate to encourage plant growth without drying the seed bed.
Advantageously, the system of the present invention including the rice straw matting has a substantially higher aerial density relative to an identical flexible matting not formed of rice straw fibers, for example relative to a conventional wheat straw matting system.
Although not wishing to be bound by any particular theory of operation, it is believed that that the high aerial density of the present rice straw matting system functions to dissipate rain energy sufficiently to protect the soil surface beneath the matting and allow plant life to flourish. The present rice straw matting of the present invention is substantially more effective in controlling erosion on surfaces, for example, bare sloped surfaces, during high intensity and/or long duration storm events, relative to conventional wheat straw and wood fiber matting systems.
In one embodiment of the invention, a method for controlling erosion is provided, including the steps of applying debated rice straw fibers in a substantially continuous, substantially even layer onto a surface prone to erosion and allowing the rice straw fibers to remain on the surface during growth of seedlings and mature plants.
The present invention also provides a method for manufacturing a rice straw blanket. The method includes the steps of pulling rice straw fibers, for example from a bulk bale of rice straw, using a blade mechanism comprising a plurality of rotating blades, the rotating blades having a speed of rotation effective to loosen and/or pull the rice straw from the bale to achieve long, thin, separated rice straw fibers. These “debated” fibers are then discharged onto a conveyor surface moving at a speed effective to cause the fibers exiting the rotating blade assembly to form a substantially continuous, substantially uniform fiber pile. This uniform fiber pile may then be utilized substantially “as is” as a covering for erosion prone surfaces.
Alternatively the debated rice straw may be utilized to form a rice straw fiber blanket in accordance with the present invention. By utilizing relatively high speed rotating blades and conveyers, the debated rice straw fibers can be readily processed and digested by conventional blanket manufacturing material handling systems.
In one embodiment of the invention, the rice straw fiber pile is mechanically stitched or bonded to form a blanket having a substantially uniform thickness. The fiber pile may be stitched at specific intervals, for example, but not limited to, between about one inch and about two inches on centers to ensure general uniformity of the blanket. Preferably, stitching is sewn with monofilament thread or twisted multifilament thread having a minimum denier of about 1,000 denier or greater.
In another especially advantageous embodiment of the present invention, a pigmented erosion control blanket is provided. In particular, a pigmented rice straw erosion control blanket is provided, for example a green pigmented erosion control blanket that is both visually appealing and effective as a ground covering.
A pigmented erosion control blanket in accordance with the present invention generally comprises a core layer comprising, preferably substantially entirely comprising rice straw fibers. In one embodiment of the present invention, the core layer consists essentially of rice straw fibers. The fiber matrix preferably comprises pigmented rice straw fibers, for example, but not limited to green pigmented rice straw fibers.
In a more specific aspect of the invention, the system comprises a flexible matting useful for controlling erosion on a surface, wherein the matting includes a core layer formed of a rice straw fiber matrix and a pigment composition deposited on the fiber matrix and effective to impart a color to the matting. The pigment composition comprises, for example a colorant component and a binder component, wherein the binder component is effective to maintain the imparted color on the rice straw for an increased period of time relative to a substantially identical system having a substantially identical pigment composition without the binder component.
Preferably, the pigment composition is an aqueous composition derived from about one part pigment or colorant, about one part pigment binder. The binder preferably comprises a polymer coating material that is effective to maintain the color on the rice straw fibers when the rice straw fibers are in use as part of an erosion control system.
This embodiment of the invention is especially useful as a visually appealing, substantially weed free, high nutrient ground cover that aids in preventing runoff of soil on newly developed land.
In a related aspect of the invention, a method of dyeing or pigmenting natural fibers for use in erosion control is provided. For example, a pigment composition is applied to fibers, preferably rice straw fibers, wherein the pigment composition includes a pigment component and binder component effective in maintaining the pigment component on the fibers for a substantially longer period of time relative to substantially identical natural fibers that are pigmented without use of the binder component. For example after the rice straw fibers have been pulled from a bulk bale as described elsewhere herein, the pigment composition comprising an aqueous mixture including a colorant component, a polymeric binder component, and an effective amount of a surfactant is applied to or deposited on the fibers.
An examples of a useful, effective method of manufacturing a pigmented rice straw blanket in accordance with the present invention is provided in the following Example. It should be appreciated that the Example is provided for purposes of example only and is not intended to limit the scope of the present invention.

EXAMPLE

Pigmentation Composition

A pigmentation solution (concentrate) is made by combining, at ambient temperature, about one gallon of latex polymer dispersion having tradename Pigment Green BN-Y Concentrate (Robert Koch Industries, Inc.) about one gallon of a binder component comprising a polymeric material, more specifically a polymer coating material having tradename Pigment Binder NW (Robert Koch Industries, Inc.) and a pint of a surfactant wetting agent, having the tradename Kinetic.
An aqueous pigmentation composition is made by combining, at ambient temperature, for example a temperature of no greater than about 85° F., in a 500 gallon tank, the pigment/binder concentrate described hereinabove, with water at a ratio of about one part concentrate to about 100 parts water. The aqueous composition is continuously agitated or stirred, for example by means of a circulating pump, to prevent pigment from settling to the bottom of the aqueous mixture.

Application of Pigment Composition to Rice Straw Matrix

While the pigment composition is being stirred, it is discharged from the tank by means of a spray nozzle onto the core layer of the matting. More particularly, the pigment composition is applied to the rice straw fibers after the stitching process, by passing the reinforced rice straw fiber matting under a low pressure spray bar which applies the aqueous composition onto a major surface of the matting.
This method of applying the pigment composition allows droplets of the composition to rapidly disperse and become effectively absorbed by and/or adhered to the rice straw fibers.
The matting is then rolled and packaged for use. Packaging of the pigmented rice straw matting of the present invention may be provided by rolling the matting and placing the rolled matting into a substantially tubular container. Preferably, the rolled matting is placed into a “breathable” fabric container, for example a container made of a porous geotextile material, such as a the material typically used in the packaging of potatoes.
Any and all features described herein and combinations of such features are included within the scope of the present invention provided that the features of any such combination are not mutually inconsistent.
While this invention has been described with respect to various specific examples and embodiments, it is to be understood that the invention is not limited thereto and that it can be variously practiced within the scope of the following claims.

Claims

1. An erosion control system comprising:

a matting element useful for controlling erosion on a surface, the matting element including

a fibrous material comprising rice straw fibers, and

a pigment composition deposited on at least a portion of the fibrous material;

the pigment composition comprising a pigment component effective to impart a color to the rice straw fibers, and a binder component effective to maintain the imparted color of the rice straw fibers for an increased period of time during use of the system relative to an identical system without the binder component.

2. The system according to claim 1 wherein the fibrous material comprises substantially entirely rice straw fibers.

3. The system according to claim 1 wherein the fibrous material consists essentially of rice straw fibers.

4. The system of claim 1 wherein the pigment composition is derived from an aqueous composition comprising the pigment component, the binder component and an effective amount of a surfactant.

5. The system of claim 1 wherein the pigment component comprises a latex polymer.

6. The system of claim 1 wherein the pigment component comprises a green pigment.

7. The system of claim 1 wherein the binder component comprises a polymeric material.

8. The system of claim 1 wherein the binder component comprises a food-grade binder.

9. The system of claim 1 further comprising a reinforcement element for maintaining structural integrity of the matting element during installation of the system.

10. The system of claim 9 wherein the reinforcement element comprises a netting element located on at least one major surface of the fibrous material.

11. A method of manufacturing an erosion control system, the method comprising the steps of:

providing a matting element comprising rice straw fibers; and

contacting at least a portion of the matting element with an aqueous composition comprising a pigment component effective to impart a color to the rice straw fibers, and a binder component in an amount effective to maintain the imparted color of the rice straw fibers for an increased period of time during use of the system relative to an identical system without the binder component.

12. The method of claim 11 wherein the aqueous composition further comprises an effective amount of a surfactant.

13. The method of claim 11 wherein the binder component comprises a food-grade binder.

14. The method of claim 11 wherein the pigment component comprises a green pigment.

15. The method of claim 11 wherein the step of providing a matting element comprises pulling rice straw fibers from a bulk bale of rice straw and discharging the pulled fibers onto a conveyor mechanism.

16. An erosion control system comprising:

a matting element useful for controlling erosion on a surface, the matting element including a fibrous material formed substantially entirely of rice straw fibers;

wherein the matting element has at least one of increased aerial density, increased flexibility, increased functional longevity, and higher silica content relative to an identical matting element including wheat straw fibers in place of rice straw fibers.

17. The system of claim 16 wherein the matting element includes a reinforcement member located on at least one major surface of the fibrous material.

18. The system of claim 17 wherein the fibrous material consists essentially of rice straw fibers.

19. The system of claim 17 wherein the reinforcement member comprises a netting member.

20. The method of claim 15 wherein the step of pulling rice straw fibers comprises utilizing a rotating blade mechanism to loosen and separate rice straw fibers prior to discharging the rice straw fibers onto the conveyor mechanism.