Field of the Invention
The present invention relates to the field of plant irrigation,
and in particular to subsoil drip irrigation systems.
Background to the Invention
It is well-known that the moisture levels of the soil,
or other medium, in which a plant is nurtured has a significant bearing on its health,
in particular with respect to the rate at which it grows. As such, it has long been
known to manage this characteristic of soils through various irrigation systems
designed to compensate for a lack of natural moisture.
Irrigation systems are broadly defined in three categories:
flood irrigation, spray irrigation and drip irrigation. While flood and spray irrigation
are effective in treating large areas of soil they are inefficient as a large proportion
of the water applied is lost to evaporation or simply does not reach the plants
for which it is intended. Moreover, the inherent lack of fine control in flood and
spray irrigation inherently risks over-hydrating the soil to which it is applied.
Drip irrigation is commonly recognised to overcome these
difficulties due to its ability to deliver a controlled water flow to match required
hydration levels at a specific location. Nevertheless, many common drip irrigation
systems do not fully exploit this, simply delivering water to the surface of the
soil in the general proximity of the plant. Again, this leads to evaporation of
water before it reaches the plant and is therefore an inefficient use of water.
Water scarcity is becoming an increasing problem in agriculture
and domestic use, both in developing and developed countries. Clearly, the inefficiency
of the above-described irrigation techniques is undesirable in this context.
Superior drip irrigation efficiency has been achieved by
sub-soil delivery systems. For examples, an irrigation device is known that has
a conically-shaped plastic hollow spike attached to (or integrally formed with)
a connector. In use, the spike is pushed into the earth while a detachable water
reservoir (typically a plastic bottle) is attached to the connector. The spike contains
one or more holes through which water then passes into the soil.
While this prior art device has the advantage of delivering
water to a subsoil level, thereby avoiding the majority of the detrimental evaporation
effects found in alternative irrigation systems, it suffers from a number of defects
that limit its efficacy in the majority of circumstances.
In particular, the holes used to control the delivery of
water into the soil are liable to be blocked, or clogged, by a number of phenomena
such as: the ingression of soil particles into the delivery device; the collapse
of the soil structure against the wall of the device; the wetting/drying of clay
compounds creating a hard baked shield around the device; and the migration of roots
towards the device. In this last case the plant may even be damaged by the device,
particularly in removal of the device from the soil.
Moreover, the device must be manually removed from the
earth once it has served its purpose (for example, at the end of the growing season).
This is labour-intensive and makes it inconvenient for even small-scale commercial
agriculture. Furthermore, as described above this may even damage the roots of the
plant that it serves.
A1 discloses an irrigation device comprising a connector end for
engagement with a liquid supply and a dispenser body adapted to receive liquid from
the connector end.
Summary of the Invention
According to an aspect of the present invention, there
is provided an irrigation device comprising: a connector end for engagement with
a liquid supply; and, a biodegradable dispenser body adapted to receive liquid from
the connector end, wherein an outer surface of the dispenser body is substantially
water-resistant with the exception of one or more permeable feeder areas from which
liquid can be released at a higher rate than from the water-resistant areas. In
preferred embodiments, the liquid supply is detachable.
Though the irrigation technique that is achieved using
the irrigation device of the present invention is generally known in the art as
"drip irrigation" it is to be understood that the physical release of liquid from
the device is actually a leaching process. The distribution of liquid from the irrigation
device is either by suction and capillary action within the surrounding soil, or
by external pressure provided by the liquid supply, or a combination of each of
Preferably, the dispenser body has a hollow core section
extending along at least a portion of the length of the body. The hollow section
facilitates the rapid saturation of the dispenser body.
The present invention provides a sub-surface irrigation
system enabling drip irrigation for any flora. The liquid passes through the connector
end into the surrounding soil substrate through the feeder area. The use of one
or more feeder areas in an otherwise water-resistant surface of the biodegradable
dispenser body enables the output of liquid to be directionally controlled. In this
way, liquid may be directed to an area of the surrounding soil substrate at which
it is most required, negating the risk of evaporation and other dispersive mechanisms
that prevent the efficient delivery of liquid to flora in other irrigation techniques.
Moreover, the water-resistant surface of the biodegradable dispenser body may be
used to maintain the structural integrity of the device during use.
The use of a biodegradable dispenser body avoids the need
to remove the device from the soil substrate. As such, the usual risks associated
with root ingression into the device and subsequent damage to roots on removal of
the device are negated. In a preferred embodiment, the connector end is also biodegradable
so that no part of the device need be removed after use. In another preferred embodiment,
the connector end is re-usable. The use of biodegradable materials means that the
irrigation device of the present invention may be manufactured easily and from inexpensive
In the present invention, the feeder areas are preferably
at least twice as permeable to liquid as the water-resistant areas, more preferably
3-1000 times more permeable, more preferably 5-100 times more permeable. The liquid
itself is preferably an aqueous liquid and may be water itself.
Preferably, up to 98% of the outer surface of the biodegradable
dispenser is water-resistant. However, the water-resistant area preferably constitutes
greater than 40%, more preferably greater than 50%, more preferably greater than
75%, more preferably greater than 90% of the outer surface of the biodegradable
In a preferred embodiment, the biodegradable dispenser
body comprises a liquid-transmissible, for example, porous, substrate and a protective
coating, wherein the protective coating provides the water-resistant outer surface
of the dispenser. In such an embodiment, the device employs a water-resistant epidermal
outer skin coating applied in a controlled manner to parts of the biodegradable
dispenser substrate to determine exit points for the water below ground and, where
appropriate, to ensure the integrity of the connection to the reservoir. However,
the water-resistant surface of the dispenser body may be realised in other ways,
such as by heat or chemical treatment of the exterior of the substrate used to form
The liquid supply may be a separate storage vessel such
as a plastic (typically PET) beverage bottle. Standard beverage bottles incorporate
an externally threaded neck portion which, in one preferred embodiment, can be coupled
to a correspondingly threaded connector end. However, any type of bottle or carton
may be used. Alternatively, the liquid supply may be coupled to the irrigation device
(or indeed several devices) through a hose system. In this case, the liquid supply
may be a water reservoir such as a water butt (typically arranged to collect rainwater)
or a mains water supply coupled to the or each irrigation device via a hose, preferably
a micro-irrigation hose, system.
The connector end may have an internally or externally
threaded portion to provide a suitable connection to the liquid supply, or may simply
be shaped so as to provide an interference-fit (whether male or female) with the
liquid supply. The connector end may be integrally formed with the biodegradable
dispenser body or may be detachable from the dispenser body so that it can be reused.
A detachable connector end may form a screw-fit or interference-fit with the dispenser
body, or may be adapted to be clamped to the dispenser body. The connector end may
be designed to accommodate common liquid storage vessels, such as plastic (typically
PET) beverage bottles. Alternatively, the connector end may adapted for connection
to bespoke storage vessels, or to hoses, preferably micro-irrigation hoses.
Biodegradable materials that may be used in accordance
with the present invention may include both man-made and naturally occurring substances.
The materials are typically formed by compression moulding, injection moulding,
extrusion, casting, pneumatic shaping and/or vacuum forming, etc. However, other
methods of manufacture and materials may be used in accordance with the present
invention. For example, in one preferred embodiment, the dispenser body is formed
from a fibreboard material, preferably corrugated fibreboard, which is folded or
wrapped and then sealed or fastened into a suitable shape and configuration. In
this embodiment, a core section of the dispenser body may be filled with a different
material. Furthermore, the corrugations of the fibreboard may be pre-filled with
one or more additives which are subsequently dispensed in use. Corrugated fibreboard
provides a relatively rigid dispenser body.
In a preferred embodiment of the present invention, the
biodegradable material of the dispenser body comprises soluble additives. As water
passes through the biodegradable dispenser it carries the additives with it into
the surrounding soil, thereby further aiding the growth of the flora it feeds. Suitable
additives may include alkalis or acids to rebalance the pH of the surrounding medium,
artificial fertilizers, and compost.
In another preferred embodiment, the dispenser body carries
one or more seeds in the outer surface of the body. The seeds may be carried in
recesses formed in the dispenser body or within a coating applied to the outer surface
of the body. In this manner, both planting and subsequent irrigation can be controlled
using a single device.
Brief Description of the Drawings
Examples of the present invention will now be described
in detail with reference to the accompanying drawings, in which:
- Figures 1A to 1D show an example of
an irrigation device having a male connector end;
- Figures 2A to 2D show an example of
an irrigation device having a female connector end;
- Figures 3A to 3C show plastic bottles
coupled to the irrigation devices of Figures 1
- Figures 4A to 4F show various arrangements
of the feeder areas upon the device;
- Figures 5A and 5B show an example of
an irrigation device having a detachable connector end which is adapted to be clamped
to the body of the irrigation device;
- Figure 6 shows an example of an irrigation
device formed from corrugated fibreboard:
- Figure 7 shows a blank from which the
embodiment of Figure 6 may be formed;
- Figure 8A shows additives disposed
upon the surface of corrugated fibreboard which may be used in the production of
the embodiment of Figure 6;
- Figure 8B shows additives disposed
within the corrugations of fibreboard which may be used in the production of the
embodiment of Figure 6;
- Figure 9 shows a screw threaded connector
end for use with the irrigation device of Figure
- Figures 10A to 10C show possible arrangements
of seeds within the dispenser body according to the present invention; and,
- Figure 11 shows schematically an example
of a micro-irrigation hose system coupled to an array of irrigation devices.
"Biodegradable" means that the material is susceptible
to being assimilated by microorganisms when buried in the ground or otherwise contacted
with the organisms under conditions conducive to their growth. All degradation products
are preferably safe, non-toxic and non-accumulable in nature, i.e. should
be subject to complete microbial degradation.
Biodegradation reactions are typically enzyme-catalyzed
and generally occur in the presence of moisture. Natural macromolecules containing
hydrolyzable linkages, such as protein, cellulose and starch, are generally susceptible
to biodegradation by the hydrolytic enzymes of microorganisms. Some man-made polymers,
however, are also biodegradable.
The present invention provides an effective device for
delivery of liquid to a sub-surface level of a surrounding medium, in order to nourish
plants growing in that medium. The following description will describe the typical
case where the liquid is water and the medium is soil, but it should be recognised
that any other suitable liquid or medium may be used in accordance with the present
invention. Examples of other suitable mediums include sand, loam, clay, and compost.
The particular geometry of the irrigation device is variable,
but each device has a dispenser body and a connector end. In use, the dispenser
body is disposed in the soil, while the connector end is attached to a liquid reservoir,
commonly a plastic bottle. Water then passes through the dispenser end from the
connector end, and into the surrounding soil. The dispenser body is designed to
deliver the water to a desired part of the soil, typically the area around the root-balls
of a plant. In order to efficiently dispense the water at the required point the
surface of the dispenser body is water-resistant apart from one or more feeder areas.
Both the location of the feeder areas and the shape and configuration of the dispenser
body are adapted to the particular use for which the device is employed. For example,
criteria affecting these factors will include the location in the soil at which
water is required, the nature of the soil (and consequent structural requirements
for the dispenser), and the rate at which it is desirable for water to enter the
The form of the device is created by moulding under pressure
and/or heat, vacuum forming or other suitable process, thereby enabling the delivery
of various shapes and configurations. In essence the shape will be linear-tubular
but may, in variations, take the shape of an ovaloid, sphere, pipe, sausage, spike,
wedge, bulb, pyramid, cone, or other combinations to serve specific application
Other methods of manufacture and materials may be used
in accordance with the present invention. For example, in one preferred embodiment,
the dispenser body is formed from a fibreboard material, preferably corrugated fibreboard,
which is folded or wrapped and then sealed or fastened into a suitable shape and
There are several configurations of shape of the device.
These variations will include differences in length, width and basic shape to accommodate
the requirements of different flora with which the device is to be employed. Typically,
the length of the dispenser will vary between 20mm and 400mm.
To further enhance stability of the device in the ground,
the exterior face of the device may incorporate radial fins, grooves, louvers or
ridges running part of or the full length of the exterior fascias. Internal fins
or other strengthening mould patterns may be incorporated in some variations to
offer similar qualities. Although in some embodiments the fins or other strengthening
structures may be formed of the same material as the rest of the dispenser body,
it is also envisaged that such structures may be formed of a different composition,
material, or method of manufacture.
The connector end of the device is in some models configured
such that it creates a substantially circular shoulder to support different configurations
of reservoir containers or vessels. The shoulder may have other geometries according
to both aesthetic and functional requirements. The shoulder of the connector end
is preferably configured such that it offers a flat platform in connection with
the soil and, as such, greater stability and strength for the device when in use.
The shape of the upper region of the shoulder will be configured in dimensions appropriate
to better support and balance a selection of reservoir containers.
Figures 1A to 1D
show a particular embodiment of the present invention in which the connector end
has a male spigot. As shown in Figure 3A,
the male connector end can be inserted into the neck of a plastic bottle. Where
the male connector end provides a simple interference-fit, it may preferably employ
ridges, ribs or other formed shapes to enhance the fit and function of the joint
Figures 2A to 2D
show a similar embodiment of the present invention in which the connector end is
female. As shown in Figure 3B, the female
connector end in some applications utilises the external screw thread of the plastic
bottle. In this example a separate internally threaded fitting is placed or formed
within the female connector end to receive the threaded neck of the plastic bottle.
As shown in Figure 3C, it is instead possible
to employ an interference-fit with the neck of the bottle to provide a suitable
As mentioned previously, the location and geometry of the
feeder areas upon the dispenser body is variable, and therefore can be adapted according
to requirements. Figures 4A to 4F show
a variety of possible arrangements of the feeder area(s) - the shaded areas represent
the feeder areas.
In the present invention, the substrate used to form the
body of the dispenser includes one or more biodegradable materials. Preferably,
greater than 75% by weight of the substrate is biodegradable, more preferably greater
than 85%, more preferably greater than 95%, more preferably greater than 99%, more
preferably substantially 100%. Preferably greater than 90% of the material degrades
within the period of 1 year or less, more preferably greater than 95%, more preferably
The substrate is generally liquid-permeable, such that
the substrate is capable of carrying liquid from the region adjacent to the connector
end to be released via the feeder areas.
The formula of substrate will determine the lifespan of
the working device and its rate of biodegradability. The functioning lifespan of
each device will vary to suit the specific requirements of the plant genus which
the device serves. Typically that lifespan may include a 20 week growing season
for a cereal crop, herb or range of perennial decorative plants but may also extend
to a full year for a sapling or be as short as a few weeks for seeds.
The substrate may be constructed from natural or man-made
materials. Such materials may be virgin or recycled. The substrate is preferably
formed from byproduct and/or waste materials.
Preferably, the substrate comprises material selected from
the group consisting of paper, paper pulp, board, sawdust, wood, wood chippings,
bamboo, bagasse, oil palm stem, popula, wood flour, fruit hull powder, moss, peat,
mulch, grasses, straw, hay, cotton, starch, seeds, seed husks, silage, cereal and
cereal husks, kernels, bread, flour, skin, faeces, manure, dung, fish cartilage,
leaves of various flora, bark of various flora, plant stems, seaweed and other naturally
growing flora, bone, bone meal, vegetables, fruit, fibre, hair, fur, feathers, clay,
shell, ash, rags, felt and other commercially produced fabrics and mixtures of any
of the preceding materials. Preferably greater than 75% of the consolidated substrate
is formed from one or more of these materials, more preferably greater than 85%,
more preferably greater than 95%, more preferably substantially 100%. These materials
may be reduced to a suitable grade and size prior to consolidation using conventional
Starch is a preferred substrate material. This can also
be used as a binder for the core substrate (discussed in further detail below).
Starch can be selected from natural starch, chemically and/or physically modified
starch, biotechnologically produced and/or genetically modified starch and mixtures
thereof. The term "starch" as used herein covers in general all the starches of
natural or vegetable origin composed essentially of amylose and amylopectin. They
can be extracted from various plants, such as, for example, potatoes, rice, tapioca,
maize and cereals such as rye, oats and wheat. The term "starch" also covers modified
starches. By modified, it is meant that the starch can be derivatized or modified
by typical processes known in the art such as, e.g. esterification, etherification,
oxidation, acid hydrolysis, cross-linking, and enzyme conversion. Such starches
include starch ethoxylates, starch acetates, cationic starches, oxidized starches,
cross-linked starches and the like.
Preferred sources of starches are seeds of cereal grains
(e.g., corn, waxy corn, wheat, sorghum, rice, and waxy rice), tubers (potato),
roots (tapioca (i.e., cassava and maniac), sweet potato, and arrowroot),
and the pith of the sago palm.
Preferably, 2-99% by weight of the consolidated substrate
is made up of fibrous material embedded in a binder material, more preferably 10-85%,
more preferably 25-75%.
An amount of water may also be present in the consolidated
substrate. This may be present as water associated with the substrate material,
or may be free water which may be removed easily by heating. Typically, the consolidated
substrate may contain up to 30% residual water. Preferably, the consolidated substrate
contains less than 10% residual water, more preferably less than 5%.
Reference to the consolidated substrate means the moulded
and substantially dried substrate which can be used directly in the dispenser body
of the present invention.
The substrate materials are preferably consolidated through
the introduction of a suitable binder to achieve a rigid dispenser. The substrate
may be consolidated either using the inherent cohesive/adhesive properties of the
core substrate material, and/or by the addition of a binder material to the core
substrate material prior to or during consolidation thereof. The process of consolidation
usually also requires the application of pressure and/or heat in order to form a
consolidated substrate which can be used in the device of the present invention.
Starch based materials are particularly preferred binder
materials. The types and properties of starch are discussed above. Unmodified starch-based
binders are generally preferred over modified starch-based binders because they
are significantly less expensive and produce comparable devices. Alternative binder
materials include waxes, fatty alcohols, phospholipids and glycerol. The binder
material is preferably present in the substrate in an amount of 1-98% by weight,
for example 15-90%, for example 25-75%.
In addition to the substrate material and binder material,
one or more optional additive materials may be incorporated into the substrate.
In one embodiment, water-soluble plugs containing these additives may be inserted
into the substrate of the dispenser. Alternatively or additionally, the additives
may form part of the substrate or binder materials. Additives may also be incorporated
into the water supply.
Natural plant enhancers such as compost, manure, potash,
bone-meal and other similar substances may be used as an additive.
For example, additives including fertilizer, fruit enhancers,
vegetable enhancers, foliage enhancers, pesticides, weed killers, micro-nutrients
(such as zinc, copper, boron, and seaweed extracts), plant growth promoters and
hormones, pH-regulators, salt binding agents and adsorbents may be incorporated
into the substrate. Other materials which are generally accepted as improving the
welfare of flora and/or improving crop yield and/or controlling pests, fungus, insects,
arachnids, slugs, snails or other infestations may also be included. Some variations
may incorporate soluble or semi-soluble or water activated or continuously live
olfactory or taste materials which will dissuade/repel animals, birds, insects,
reptiles, amphibians or other undesirable creatures from the proximity of the device.
The preceding additive materials may be formulated with the binder and/or with the
substrate prior to consolidation of the substrate. Alternatively, or in addition,
the additive material may by incorporated into the substrate after consolidation
thereof, for example, by soaking the substrate in a solution containing the additive
The pH-controlling agents can be used to control the acidity
of the immediate environment, and agents such as gypsum and activated charcoal can
minimise the impact of adverse chemical contaminants and salt in the soil or medium,
as well as to improve germination, and/or to aid and accelerate plant establishment.
Suitable pH additives include lime, chalk, gypsum and peat.
Water retaining substances and wetting agents, which can
be synthetic or natural material (such as clay minerals, e.g. bentonite and
zeolite clays, or gelatine products, or surfactants such as non-ionic, anionic,
cationic and amphoteric surfactants or other wetting adjuvants), can be included
to prevent overly rapid water loss from the substrate. Examples of such water-retaining
substances include silica gels and so-called "super absorbents" such as super absorbent
acrylic polymers. In the case of wetting agents, these assist in dispersing the
water throughout the medium, and allow less absorbent forms of substrate material
to be used.
Suitable types of pesticides include herbicides, fungicides,
insecticides and nematicides.
Natural earth fillers can be included in the substrate
for a stronger product. Suitable fillers include but are not limited to clays such
as bentonite, amorphous raw products such as gypsum (calcium sulfate dehydrate)
and calcium sulfate, minerals such as limestone and man made materials such as fly
ash. These natural earth fillers are able to take part in the cross linking and
binding that occur during consolidation of the substrate material. Other examples
of useful fillers include perlite, vermiculite, sand, gravel, rock, limestone, sandstone,
glass beads, aerogel, xerogels, seagel, mica, clay, synthetic clay, alumina, silica,
fused silica, tabular alumina, kaolin, microspheres, hollow glass spheres, porous
ceramic spheres, calcium carbonate, calcium aluminate, lightweight polymers, xonotlite
(a crystalline calcium silicate gel), lightweight expanded clays, hydrated or unhydrated
hydraulic cement particles, pumice, exfoliated rock, and other geologic materials.
Preferably, the additive material (other than substrate
and binder) is added in an amount of 1-50%, more preferably up to 20%, more preferably
up to 10%, more preferably up to 5%, by weight of the consolidated substrate.
Baking powder and other materials, such as leavening agents,
which release gases, (e.g., sodium or calcium bicarbonates or carbonates)
can be included in the compositions of the invention to elevate the porosity of
the final structure by introducing a source of carbon dioxide gas which is released
in the mould.
Glycerol, microcrystalline wax, fatty alcohols and other
similar organic molecules can be added as a mould release agent, and to produce
a smoother surface on the finished product. These mould release agents can be added
from 0-10% by weight of the consolidated substrate, preferably 1-5%.
The additional materials can be predisolved or can be added
dry to the substrate prior to consolidation thereof.
With regard to the process for production of consolidated
substrate, any amount of pressure can be used that achieves the desired product.
For example, pressure between approximately 14kPa to 21 kPa (2-3 psi) may be appropriate.
Likewise, any amount of heat may be used that achieves the desired result. For example,
in one embodiment, the heat used to mould the device of the present invention is
preferably between about 50-250° C.
In a preferred embodiment, the binder is added to the unconsolidated
substrate material or vice versa, and a substantially homogenous mixture is produced
by simple mixing or equivalent process. Water is usually added during or after mixing,
or may be added to the substrate and/or the binder material prior to mixing. The
optional additive may also be advantageously added to the unconsolidated mixture.
Varying amounts of water can by added to facilitate different
types of moulding, since the form of the pre-moulded product is dependent on the
mould and the other process conditions which may be applied to produce a consolidated
Where starch is used as a binder, it is preferably pre-gelled
and mixed until a substantially homogeneous mixture is generated.
With regard to the coating of the dispenser, biodegradable
polymers that may be used to coat or impregnate the outer surface of the substrate
include a range of water-resistant natural polymers, synthetic polymers, such as
polyesters, polyester amides, polycarbonates and the like, and naturally-derived
semi-synthetic polyesters (e.g. from fermentation).
The coating that is applied to, or produced at the surface
of the substrate is preferably a water-resistant and biodegradable film. In a preferred
embodiment, the film is substantially water impermeable.
Besides being water-resistant and biodegradable, the outer
coating may exhibit certain other physical properties, such as stiffness, flexibility,
water-resistance, oil-resistance, solvent resistance, strength, elongation, temperature
stability, moisture vapour transmission and gas permeability.
The water resistant outer coating preferably comprises
material selected from the group consisting of PVA, pitch, bitumen, grease, fat,
oil, plastic, acrylic, cellulose, resin, sap, clay, waxes, wax blends, paraffin
(synthetic wax); shellac; xylene-formaldehyde resins; drying oils; reconstituted
oils from triglycerides or fatty acids from the drying oils to form esters with
various glycols (butylene gylcol, ethylene glycol), sorbitol, and trimethylol ethane
or propane; synthetic drying oils including polybutadiene resin; natural fossil
resins including copal, damar, elemi, gilsonite, glycol ester of damar, copal, elemi,
and sandarac, shellac, Utah coal resin; rosin and rosin derivatives including gum
rosin, tall oil rosin, and wood rosin, rosin esters formed by reaction with specific
glycols or alcohols, rosin esters formed by reaction with formaldehydes, and rosin
salts (calcium resinate and zinc resinate); phenolic resins formed by reaction of
phenols with formaldehyde; polyester resins; epoxy resins, catalysts, and adjuncts;
coumarone-indene resin; petroleum hydrocarbon resin; terpene resins; urea-formaldehyde
resins; triazine-formaldehyde resins; modifiers; cellulosic materials including
carboxymethylcellulose, cellulose acetate and ethylhydroxyethylcellulose; acrylics
and their copolymers; methyl methacrylate; ethyl methacrylate; melamine; polyamides;
polylactic acid; soybean protein; aliphatic polyesters, polyester copolymers with
aliphatic and aromatic blocks, polyester amides, polyethylene oxides or polyglycols,
polyester urethanes and mixtures of any of the foregoing materials.
Appropriate coatings are biodegradable and should not significantly
impact the compostability of the product.
These materials can be applied through a process of dipping,
spraying, painting or an alternative method which delivers the required control
of covering. Alternatively, the outer coating may be pre-formed and applied to the
substrate, for example, by adhesion or shrink wrapping. The coating process may
be either a hot or cold process. Bonding processes for application of coatings of
water-resistant material are known in the art. Before, during, or after any of the
moulding processes, coatings can be applied to the surface of a consolidated substrate
Alternatively, the surface of the substrate can be physically
or chemically modified such that it is rendered water-resistant. For example, the
surface could be cross-linked (by heat, chemicals or UV light) to form a polymeric
coating. Such cross-linking could be carried out on the substrate surface, or on
a coating applied to its surface.
In addition to the coating material, a number of optional
additive materials may be incorporated into the coating in order to impart desired
properties. These include, but are not limited to plasticizers, lubricants, fillers
and natural polymers.
Plasticizers and lubricants may optionally be added in
order to improve processing, such as extrusion, film blowing, spreading or spraying,
or final mechanical properties, particularly of polymer blends that are relatively
stiff. A stiffer polymer blend may be dictated by other performance criteria, such
as high temperature stability, strength, lower elongation, higher dead-fold, resistance
to "blocking" during and after processing, and the like. In such cases, a plasticizer
may allow the coating to satisfy certain processing and/or performance criteria.
Particulate fillers may optionally be added for a number
of reasons, including but not limited to, increasing the Young's modulus, dead-fold
properties, rigidity, breathability, thermal stability and for decreasing the cost
and tendency of the coating to "block" or self-adhere during processing.
In general, fillers within the scope of the invention will
generally fall within three classes or categories: (1) inorganic particulate fillers,
(2) fibers and (3) organic fillers.
The combination of substrate materials will provide a porous
dispenser. In some applications the conduit quality of the substrate may be further
enhanced through a process of drilling holes, groves, channels or other carved,
cast or milled, facet to direct the movement of water through the device internally
and as exit point(s). Alternatively, porosity may be enhanced through using graded
and /or engineered materials radiating from the core or in varying layered strata.
The substrate may be of a uniform or non-uniform nature.
Variations of strata or radial configuration of layers of substrate materials may
be employed to enhance or retard water flow rates.
The speed of water transmission will depend on the substrate
material and its level of consolidation. For example, a more highly consolidated
substrate material is likely to have a lower porosity.
Porosity may be easily measured by any of the methods known
in the art. For example, the volume/density method, the water saturation method
and the water evaporation method may be used. The consolidated substrate of the
present invention preferably has a porosity in the range of 0.01-0.95, more preferably
0.05-0.75, more preferably 0.1-0.5.
The saturation of any plant enhancing additive will allow
a controlled leaching of the compound into the water exiting the device and, as
such, entry into the soil in the immediate proximity to the device and the root-ball
of the plant(s) benefiting from the device.
As stated previously, the outer surface of the biodegradable
dispenser exposed to the soil is substantially water-resistant with the exception
of one or more feeder areas, thereby enabling directional control of the output
of the irrigation device. In a preferred embodiment, this effect is achieved by
coating the surface with a nonporous material. The feeder areas may be created by
the removal of the coating from, or simply not applying the coating to, suitable
exit portals, holes, points or windows. The configuration and positioning of the
exit windows will define the positioning/depth of water exit point(s). This configuration
will determine directional flow of the exiting water. The size of the exit window(s)
will contribute to the rate of exit flow of the water. The configuration of the
exposed core substrate material (the windows or portals) will deliver a choice of
directional flow varying from one degree through to three hundred and sixty degrees
- full radial saturation.
The employment of varying formulation(s) of waterproof
or partially waterproof epidermal/outer skin coating will further determine the
lifespan of the working device and its rate of biodegradability.
Although the embodiments shown in Figures
1 to 4 have a connector end integrally formed with the dispenser, the connector
end may alternatively be a separate component. Figures
5A and 5B show an embodiment of the present invention in which the connector
end is a separately formed connector component designed to be clamped around a shoulder
portion of the dispenser body. The clamp-type connector end in this embodiment has
a threaded male spigot to facilitate connection to a water supply. The water supply
may be a liquid reservoir directly attached to the clamp connector, or may be a
hose which is in turn coupled to a water supply. The separately formed component
is in one typical embodiment formed from plastic. Alternatively, it is also envisaged
that the component may be formed of organic and/or biodegradable materials.
As shown, the connector end has a lower part and an upper
part, and a living hinge allowing the parts to be closed together. An engineered
closure mechanism such as a snap-fitting (not shown) allows the connector end to
be released and refastened on multiple occasions. The water supply is coupled to
the upper part while, in use, the shoulder portion of the dispenser body is clamped
between the lower and upper parts. Closing the two main parts of the connector forms
a watertight seal for example, through the integration of O-ring seal(s) or similar
mechanisms into the connector end (not shown), and ensures the flow of water through
the dispenser body. A mesh sheet (not shown), or other filter may be incorporated
into the connector to offer filtration.
A valve mechanism utilising flow control mechanics may
be incorporated into the upper or lower sections of the plastic connector.
Variations of the plastic connector may incorporate engineered
adaptors to facilitate further connection to micro, standard and unique bore configurations
of domestic or commercial irrigation hose systems.
Figure 6 shows
an embodiment of an irrigation device in which the dispenser body is formed from
a fibreboard material, preferably corrugated fibreboard, which is folded or wrapped
and then sealed or fastened into a suitable shape and configuration. In some examples,
the dispenser body may be formed of a single fibreboard blank, such as that shown
in Figure 7, which is wrapped around itself
to achieve a substantially solid cross-section through the dispenser body. The shape
of the blank may be altered according to requirements. For example, the removal
of a corner of the blank will provide a female connector end in the completed device.
This technique can also lead to a natural screw thread in the connector. Alternatively,
the fibreboard material may be wrapped around a core section of the dispenser body
which is filled with a different material. Furthermore, the corrugations of the
fibreboard may be pre-filled with one or more additives which are subsequently dispensed
in use. These may be provided either between or within the corrugations. In one
example, a sheet containing the additional additives is placed on the blank before
it is rolled up into the dispenser body, resulting in the additive sheet being held
between the layers of the dispenser body. Corrugated fibreboard provides a relatively
rigid dispenser body.
Figure 8A shows
the unrolled corrugated blank with additives placed upon the corrugations. Alternatively,
additives may be placed within the corrugations as shown in Figure
Figure 9 shows
an embodiment of a screw threaded connector end for use in the embodiment shown
in Figure 6. The connector end includes
a screw threaded cap for connection to the neck of a plastic bottle and carries
a hollow, screw threaded elongate body which can be screwed into the dispenser body.
As one skilled in the art would recognise, similar screw threaded connector ends
may be used in connection with other embodiments of the present invention.
The present invention may carry seeds to plant in the surrounding
medium. Preferably, these will be located on or within the water permeable feeder
arrears of the dispenser body. In some examples the seeds will be embedded in the
dispenser body, while in others they will be attached to the surface. A preferred
method for attaching the seeds is to set them in a soluble gelatine sheet (for example,
the seeds may be placed on one side of the sheet and the sheet then folded so that
the seeds are enveloped entirely within the gelatine). The sheet is then attached
to the feeder area at the appropriate location. Since the gelatine sheet is soluble
the seeds will then become detached from the device when it is in use. Other soluble
adhesives may also be used in accordance with the present invention. Figures
10A to 10C show possible seed arrangements where the seeds are set into
rebates within the dispenser body. In Figure 10A
each seed is contained in a separate gelatine capsule set into the dispenser body.
In Figure 10B the rebates within the dispenser
body are sealed by gelatine. In Figure 10C
the seeds are held in rebates within the dispenser body without the presence of
gelatine. It is not always necessary to provide rebates in the dispenser body when
an adhesive sheet is used.
Figure 11 illustrates
an example of an array of irrigation devices in accordance with the present invention
coupled together via a network of hoses to a common water supply. The devices may
be coupled in parallel or in series, or a combination of the two, to the water supply.
The water supply may be a water butt typically used to collect rainwater, or a mains
supply of water at a tap. The end connector in this example includes pipe fittings
to receive, preferably as a push-fit, the end of the hoses used to connect the devices
into a network.
Although the embodiments described above show the dispenser
body extending predominantly parallel to the longitudinal axis of the connector
end (in order to penetrate the earth or other medium), it would be recognised by
one skilled in the art that a variety of alternative shapes may be used in accordance
with the present invention. In particular, the dispenser body may extend in part
transverse to the axis of the connector end (for example, in order to provide a
greater surface area in contact with the medium at ground, or indeed any other,
level). The dispenser body may extend separately in a plurality of transverse directions
from the connector. Moreover, a number of dispenser bodies may be attached to a
The various elements of the device (such as the dispenser
or the connector) may be colour-coded to indicate properties of the device. For
example, the colour coding may indicate the nature of the additives or embedded
seeds incorporated into the device. It also envisaged that colour coding may be
used to indicate preferred watering frequencies.