AN IMPROVED ENCLOSED WATER ABSORBENT SYNTHETIC PLANT GROWTH

MEDIUM

CROSS REFERENCED TO RELATED APPLICATIONS [0001] This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional

Application No. 60/782,078, filed March 14, 2006.

TECHNICAL FIELD

[0002] The present invention relates to the field of hydroponics, particularly to the area of hydroponic growth media, and more particularly to the field of recyclable synthetic growth media.

BACKGROUND ART

[0003] Hydroponics is crop production using mineral nutrient solutions rather than soil containing silt and clay. Land plants may be grown with roots only in liquid nutrient solution and/or gases including but not limited to oxygen, hydrogen and others. [0004] There are two types of hydroponics - solution culture and medium culture.

Solution culture does not use a solid medium for the roots, just the solution itself. Nutrient solutions used in hydroponics are mostly inorganic and ionic and include cations such as calcium, magnesium, and potassium. Nitrogen, sulfur, and phosphates are also supplied in nutrient solutions in the form of salt solutions with corresponding cations. [0005] Medium culture utilizes a solid medium for the roots. Typically, nutrient media is delivered to individual plants through feed tubes and individual drippers that supply nutrient media directly to the base of each individual plant. Typical media are sand, gravel, and rockwool. Rockwool is currently the most popular medium. It is made from basalt rock. It is prepared for use by heating to a high temperature and spinning it back together to create a "cotton candy" appearance.

[0006] However, there are some problems attached with the use of rockwool. When it is dry, rockwool becomes friable and its mineral particles may be inhaled. It causes a high pH level which requires constant monitoring and removal of leached out minerals. In addition, rockwool can be used for only three or four generations or growth cycles. Finally, rockwool is not recyclable meaning that after it is no longer usable it must be disposed of as a hazardous waste thereby adding to its overall cost as well as the overall production cost of the plants grown using a rockwool medium.

[0007] In addition, the root zone oxygen level can be very low when using rockwool due to the low air porosity of rockwool, especially at the later stage when the substrates are compacted. In some cases the oxygen level can drop to as low as 1.8 ppm.

[0008] This low oxygen condition can be exacerbated by the use of black tubing to supply nutrient media to plants. The black tubing retains heat and causes the temperature of the growth media to rise reducing its oxygen carrying capacity. This low oxygen condition in rockwool or other growth media can make plants susceptible to root disease as well as reduce their growth potential.

[0009] Traditional hydroponic medium culture systems, especially those that utilize rockwool, can develop adverse pH conditions. Because drippers supply water to the surface of the media, some water remains on the surface and leaches out minerals from the rockwool media. Various components of the basaltic rockwool include iron, sodium, aluminum and calcium which can be leached out and lower the pH in the immediate area of the growing plant. This condition requires periodic rinsing of the rockwool in order to bring the pH to acceptable levels.

[0010] In addition to the low oxygen problem, prior art hydroponic culture media systems are susceptible to the rapid spread of disease. Because water and nutrients are traditionally delivered using irrigation lines and drippers, if there is plant disease outbreak, such as Pythium, Fusarium, or Phytophthora, among others, the recirculating systems can spread that disease throughout an entire hydroponic system.

[0011] Two areas in which soilless plant cultivation is employed is in green houses and in urban locations, such as roof tops which may have open areas but little or no soil in which to grow plants. In both locations, a type of irrigation mat, supplied under the name AQUAMAT™ has been developed by Soleno Textiles in Laval, Quebec, Canada that provides for both water uptake and distribution to plants. The irrigation mat is described in U.S. Patent No. 7,152,370 to Caron, et al. and is hereby incorporated by reference in its entirety. The AQUAMAT™ material is a multi-layer textile material in which the top layer is a water permeable, anti-rooting cover that is UV resistant on its outer side. The bottom layer is sealed to the top layer and is watertight to prevent leaking or seepage of water from within the sealed material. Two inner layers include an upper layer that acts as an evaporation blocker and a lower absorbent felt mat that enables the even distribution of the retained water within the sealed package. [0012] One problem with the AQUAMAT™ material and system and with similar materials is that it is not constructed to receive plants that are not supplied their own soil, such as in pots or flats. Thus, although it is an excellent water supply material, it is not available to unpotted plants that may otherwise be cultivated in unconventional environments such as roof tops, patios, and other soilless locations. [0013] Thus, there exists in the field a need for a both a material that can both control water availability and sustain the cultivation of unpotted and otherwise unsupported plants.

DISCLOSURE OF INVENTION

[0014] The present invention broadly comprises an improvement, for an enclosed water retention system, the enclosed water retention system including an upper water permeable, anti- rooting, UV resistant layer having a light colored outer side and a dark colored inner side, an evaporation block layer adjacent the upper water permeable UV resistant layer with the evaporation block layer having at least one fluffy polymer layer to reduce water evaporation, a water distribution layer adjacent the fluffy polymer layer enabling uniform water distribution in all directions throughout the enclosed system, and a water tight bottom layer, in which the top and bottom layers are sealed together enclosing the water retention system to retain water within the enclosed medium. The improvement includes a recyclable synthetic plant growth medium having at least one polymer nonwoven material in a fixed form, at least one delivery tube in functional association with the form, and an attachment means attaching the delivery tube to the form; a root barrier, wherein the root barrier is water permeable and UV resistant and is positioned below the at least one polymer nonwoven material, and in which the recyclable synthetic plant growth medium is positioned between the water permeable upper layer and the water distribution layer, and a water removal system embedded within the evaporation block layer and/or the water distribution layer. [0015] The present invention also broadly comprises a system for irrigating plants using a synthetic recyclable growth medium that includes an irrigation mat with the irrigation mat having a water permeable top layer, a nonwoven polymer form, at least one delivery tube, a water permeable root barrier, a fluffy polymer evaporation barrier, a water distribution layer, a water removal system embedded within the evaporation barrier and/or the water distribution layer, and an impermeable water barrier layer. Along with the irrigation mat, the irrigating system also includes a power source, a nutrient fluid storage and treatment tank, a vacuum motor connecting the water removal system and a pump motor, with the pump motor connected to the nutrient storage and treatment tank. It will be recognized by those skilled in the art that such a system may include more than one of the components described here. [0016] An object of the present invention is to provide an improved water retention system that enables the support of plant growth using a synthetic growth medium.

[0017] A second object of the present invention is allow plant growth to access the retained water of the water retention system.

[0018] A third object of the present invention is enable the delivery of liquid plant nutrients to the synthetic growth medium.

[0019] An additional object of the present invention is to provide a water control system for developed locations that allow for plant cultivation.

[0020] A further object of the invention is to provide for a recirculation system to remove excess water and depleted plant nutrient fluid and the input of fresh or replenished plant nutrient solution.

BRIEF DESCRIPTION OF DRAWINGS

[0021] The nature and mode of the operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing Figures, in which:

Figure Ia is a top perspective view of the synthetic water absorbent synthetic plant growth medium ("growth medium") of the present invention in which the growth medium is wrapped in a UV resistant wrap;

Figure Ib is a top perspective view of the growth medium showing nutrient delivery tubes attached to the top of the growth medium;

Figure Ic is a top perspective view of an alternate embodiment of the growth medium in which the nutrient delivery tubes are positioned within the growth medium;

Figure 2a is a cross section of the growth medium of the present invention taken along line 2a-2a of Figure Ia and showing the delivery tubes attached on the top surface of the growth medium;

Figure 2b is a cross section of the growth medium of the present invention taken along line 2b-2b of Figure Ib and showing the delivery tubes positioned within the growth medium;

Figure 3 is in an enlarged view of the roots of a plant growing in the growth medium with nutrient fluid trapped within the UV wrap and retained around the roots of the plant;

Figure 4 is a schematic view a hydroponic plant growth system in which a plurality of growth medium forms of the present invention are connected to construct a network of forms; Figure 5 is a side view of a water retention system of the prior art;

Figure 6 is a cross section of the prior art water retention system showing an alternate embodiment in which delivery tubes are used to deliver water or nutrient fluid to the system;

Figure 7 is a cross section of the system of the present invention showing the improvement in the prior art system; and,

Figure 8 is a schematic representation of a recirculating irrigation system utilizing the present improvement.

BEST MODE FOR CARRYING OUT THE INVENTION [0022] At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical structural elements of the invention. While the present invention is described with respect to what is presently considered to be the preferred embodiments, it is understood that the invention is not limited to the disclosed embodiments. The present invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0023] Adverting to the drawings, Figure Ia is a top perspective view of the recyclable synthetic water absorbent plant growth medium ("growth medium") of the present invention in which the growth medium is in the form of at least one nonwoven polymer in the shape of a slab or other shape (form 10") and is wrapped in a UV resistant wrap 13. Also seen is a preferred embodiment in which perforations surround at least one hole cover 14. As will be explained below, in the preferred embodiment, at least one perforated cover(s) 14 are easily removed to reveal at least one hole 14a. Hole 14a allows placement of a plant seed or seedling on or in form 10. [0024] Wrap 13 is an aquaculture wrap having a double purpose. First, it keeps out light and spores that may adversely affect the plants. Second, it retains the nutrients fed to form(s) 10 through tubes 11 as tubes 11 are inside wrap 13. The retention of the nutrients allows the nutrients to concentrate at the roots of the plants. In one embodiment, wrap 13 is comprised of two layers of polyethylene having a gauge of 2.63 mils. The two layers include an inner black polyethylene layer 13a (~ 10%), made from low density polyethylene that retains heat and nutrient fluid, and an outer white polyethylene layer 13b (~ 90%) made from a medium density polyethylene, that blocks UV radiation. Preferably, wrap 13 is manufactured to include perforated holes 14a spaced about 8-12 inches apart, depending on the plant being grown. Holes 14a are easily opened to provide an opening to place the plants onto form 10. Wrap 13 is produced by Peel Plastic Products Ltd., 49 Rutherford Road, South Brampton, Ontario L6W 3J3 Canada.

[0025] Figure Ib is a top perspective view of the growth medium showing nutrient delivery tubes 11 ("tubes 11") attached to the top of form 10. In one embodiment, form 10 is approximately 36 inches or one meter in length, about 6 inches wide and about 2.0-5.5 inches in depth. Persons of skill in the art will recognize that other sizes may be more suitable for certain plant growth scenarios. For example, the material of the medium may be formed into one inch

cubes or other configurations. In a preferred embodiment, form 10 can be manufactured into any desired length or, after manufacture, cut into any desired length.

[0026] In one embodiment, the medium is comprised of at least one nonwoven polymer fiber ("polymer") and possesses a uniform density throughout the entire formation (slab, cube, etc.). In one example of this embodiment, the polymer comprises 100% polyester (polyethylene terephthalate or PET). Other possible polymers include, but are not limited to, basofil (a melamine derivative) PBX Kanekaron (acrylonitrile/vinylidene chloride copolymer), PLA (polyactic acid, such as Ingeo ^™ fiber from Natureworks PLA, polypropylene, acrylic, nylon, propylene, PTA (purified terephthlalic acid), and CAN (acrylonitrile). Still other polymers include, but are not limited to, ethylene dichloride, MEG (monoethylene glycol), ethylene glycol, FDG (polyamide fiber), benzene, and styrene.

[0027] In other embodiments, the medium includes cellulose derivatives distributed throughout the medium again with substantially uniform density. These cellulose fibers include, but are not limited to, rayons, both viscose and acetate rayons, Iyocel (regenerated cellulose) and visil, a viscose fiber. Typically, the mixtures range from 80-100% polymer and 0-20% cellulosic material. In a preferred embodiment, the cellulosic material ranges from 1 - 10%. Cellulosic material is defined as the rayon and rayon-type fibers and other fibers that perform the same or similar function as that of rayon in the medium. [0028] Form 10 also includes at least one delivery tube 11 ("tube" or "tubing" 11") attached to form 10 by an attachment means such as a textile staple 12 which attaches tube 11 to form 10 at approximately 6-12 inch intervals. In a preferred embodiment, delivery tube 11 is fabricated from TYVEK ^® . Suitable staples 12 are made by Avery Dennison, Framingham, MA

, having a length ranging from 2-6 inches. A preferred embodiment is an SPCl 800, 2.875 inch staple (73mm) made by Avery Dennison. In one alternate embodiment, the attachment means may be a suitable adhesive able to retain sufficient adhesiveness in a moist or wet environment and if buried underground. One example of a suitable adhesive is a hot melt glue Hot Melt Bonding Adhesive Resin: Polyolefin-E from International Irrigation Systems, St. Catherines, Ontario, Canada L2T 3N3. [0029] Tube 11 is considered to be in functional association with form 10 meaning that tube 11 functions to provide water and nutrients to the medium of form 10 which in turns acts as a nutrient source for the growing plants. In a preferred embodiment, form 10 will comprise two or more TYVEK ^® tubes 11, which in one embodiment are attached to the top surface of form 10 using textile staple 12. In a more preferred embodiment, tube 11 is a type of TYVEK ^® comprising micropores averaging about one micron in size which provide for an efficient flow of water and nutrients to each plant without the dangers of over watering. By using a tube 11 that

includes these micropores, less water is needed to be supplied to the plants and less maintenance is needed to maintain efficient flow to the plants. In addition, the one micron pore size provides a "biosecurity" feature by preventing harmful microbes from being introduced to the plants through the aqueous nutrient stock fed to the plants. Most infectious microbes are greater than 1 micron in size. Tube 11 with micropores may also be used to supply oxygen, hydrogen and other gases using procedures that are well known to those having skill in the art, such as bubbling the particular gas into the fluid being delivered through tube 11.

[0030] A type of TYVEK ^® tube 11 possessing one micron pores is manufactured and supplied by International Irrigation Systems as WHD+C TYVEK ^® tubing. In a more preferred embodiment, WHD+C TYVEK ^® may include a noncompressible plastic insert lib (not shown in Figure Ia) placed within TYVEK ^® tube 11 during its manufacture allowing it to be buried to protect tube 11 from destruction by UV exposure, vermin and small animals such as rodents. In addition, as explained below, use of WHD+C TYVEK ^® tubes enables even distribution of water- borne nutrients to the plants placed onto form 10. In the custom or continuous medium roll embodiment, tube 11 is attached to form 10 as form 10 is unrolled. Connection fittings are used to attach the ends of reels of tubing 11 together during this assembly process. [0031] Figure Ib also depicts a preferred embodiment of form 10 in which the nonwoven polymer is formed into a densified top layer 10a adjacent to a lower less dense layer 10b. Densifϊed layer 10a is about 0.25-1.25 inch" thick at the top surface of form 10. This densified layer serves to better support the plants placed onto the slab. The densified layer is preferably between 1.25 and 4 times denser than the lower portion of form 10. The same polymer materials and cellulosic materials described above are present in the densified layer in the same proportion as the remainder of form 10. These mixtures of polymer and cellulosic fibers and their methods of making and densifying (varying density) are well known to those skilled in the art. For example, a 100% polyester form and a 90-10% polyester-rayon blend both suitable for use as recyclable synthetic growth media, are manufactured by Fybon Industries, Ltd, of York, Ontario Canada having a weight of 30 oz./sq. yd. and a width of 43 inches and a overall length of about 22 yards. [0032] Figure Ic is a top perspective view of an alternate embodiment of the growth medium in which the nutrient delivery tubes are positioned within the growth medium. In this embodiment, a roll of tubing 11 is unrolled and incorporated into form 10 as form 10 is fabricated forming an interstial space around tubing 11 with nonwoven polymer material both above and below tubing 11. [0033] Figure 2a is a cross section of the growth medium of the present invention taken along line 2a-2a of Figure Ia and showing the delivery tubes attached on the top surface of form

10. Figure 2b is a cross section of the growth medium of the present invention taken along line 2b-2b of Figure Ib and showing the delivery tubes positioned within the growth medium. [0034] Figure 3 is in an enlarged view of the roots of plant 20 growing in the growth medium with nutrient fluid trapped within the UV wrap and retained around the roots of the plant. Plant 20 is seen emerging from form 10 through hole 14a. Plant 20 may be any type of plant. Some examples well known in the art include cucumbers, strawberries, peppers and tomatoes, however, these examples are not intended to limit the type of plants able to be grown in the synthetic plant growth medium of the present invention. Roots 22 are seen extending from densified layer 10a through layer 10b to the bottom of form 10. Wrap 13 acts as a root barrier to keep plant 20 confined to within form 10. Wrap 13 is a watertight barrier that holds nutrient 11a within the confines of the wrapped form 10. The arrows signify nutrient solution 11a flowing down from tubes 11 and concentrating around roots 22 as shown by the arrows. Insert 11a is seen within tube 11. [0035] Figure 4 is a schematic drawing of a hydroponic system utilizing the medium of the present invention configured as a slab or form 10. Tank 30 is connected to several slabs 10 through hose 31. Valve 32 may be a simple on-off valve or a pressure control valve positioned to control the flow of nutrient fluid from tank 30. Forms 10 are held in troughs 34 and are connected to each other by connection fittings 18. Connections 18 for different types of tubing 11 are well known to those of skill in the art. Form 10 is contained within wrap 13 (not shown in Figure 4) except for hole 14a in the top for placing the plants to be grown. Nutrient solution 11a is fed from tank 30 through hose or pipe 31 and into tubes 11 in either a gravity fed or a pressurized system. Slits made in wrap 13 allow nutrient fluid 11a to drain into trough 34 and be replenished by new nutrient fluid lla from tank 30 maintaining constant access to replenished or new nutrient fluid lla by the plants. The fluid passes from tank 30 or other source through a series of one or more hoses or pipes fitted with a pressure compensating flow controller to produce an automatic watering/feed effect. Pressure compensating flow controllers are supplied by International Irrigation Systems. As described below, in the preferred embodiment of the system shown in Figure 4, tubing 11 is WHD+C TYVEK ^® the micropores of which open simultaneously only after a back pressure of 4-10 psi is reached. After the micropores open, the plants at the downstream end of the connected forms 10 receive the nutrient fluid at the same flow rate as the plants at the upstream end of form 10. Pressure compensating flow controllers 23 control the feed flow and pressure entering tubing 11.

[0036] Typically, hydroponic plant systems produce uneven growth and fruition as the plants positioned near the upstream or entry point of the nutrient fluid will absorb a greater proportion of the nutrients than the plants further downstream from the nutrient entry point.

Using the preferred WHD+C TYVEK ^® tubing enables each plant on a particular form to receive equal amounts of nutrient thereby providing even plant growth throughout the slab. The micropores of the WHD+C tubing 11 are designed to open simultaneously due to back pressure created in tube 11. The micropores are about 1 micron in diameter. As the nutrient fluid enters and fills tube 11, the micropores remain closed creating back pressure in the tube. When sufficient back pressure is created, typically about 4-10 psi, all the micropores open simultaneously allowing for evenly balanced distribution of nutrient fluid throughout form 10. Once initiated, this even distribution is continued as long as flow to form 10 is maintained. [0037] It should be noted that the nutrient fluid may be unique for each type of plant and even for each geographic area. Moreover, the nutrient fluid may change in type or concentration of nutrient component as the particular plant matures. Such changes do not affect the performance of the medium of form 10 or TYVEK ^® tubing 11.

[0038] Another unexpected advantage over the prior art, including the use of rock wool plant growth media, is the lack of salting out of the nonwoven polymer and polymer— cellulosic media and the consequent reduced amount of water needed to be supplied to the plants. Using rock wool and the usual drip tube method causes the rock wool media to salt out thereby exposing the plants to an abnormally high level of salt. This causes stress in the plants and reduces their growth and yield. This salting out effect accelerates as the rock wool media is reused for additional plant growth cycles. Use of the nonwoven media of the present invention allows the grower better control over the flow of water and nutrient fluid and reduces the overall amount of water needed to be supplied to the plants. The nonwoven medium retains water in the medium, especially when contained in wrap 13. The water is not drawn to the surface of the media where it evaporates, preventing salts from collecting on the surface of the media near the plants through water evaporation. This reduces or eliminates the need to flood the media with water to leach out the collected salts. Because there is less runoff, less evaporation at the surface and less need for leaching out salts formed at the media surface, use of the polymer and polymer- cellulosic media reduces the total amount of water and nutrient fluid needed to grow a crop as compared to use of prior art (rock wool) media. Moreover, in addition to reducing the stress on the growing plants, the lack of salting out allows the media to be reused without significant loss of growth and yield in successive plantings.

[0039] Nutrient fluids previously known to those skilled in the art may be used with the medium comprising form 10. Typically, formulas for nutrient fluids are not only unique to each type of plant, but often differ as to geographic region and even by individual grower. Each nutrient fluid comprises nitrogen, phosphates, and potassium in various ratios. The polymer and polymer/cellulosic media described are capable of using any of these various nutrient formulas to

initiate and maintain growth from seeds and/or seedlings to mature plant with ripened fruit ready for harvesting.

[0040] The medium provides advantages over the prior art in that it is recyclable and consequently significantly reduces the pressure on landfills that currently receive unrecyclable synthetic growth media such as rock wool. The nonwoven polymer media, such as polyester, provides structure and air porosity. In the preferred embodiments that include cellulosic material such as rayon, the cellulosic material enables the medium to retain water until the roots of the plants mature sufficiently to retain water on their own. Moreover, roots from previous plantings are also retained in the medium to help retain water for new plantings. Using the medium of form 10, it is possible to use the same form 10 for at least three different plantings, meaning growth from seed or seedling to mature fruiting plant. In addition, the old roots from prior plantings can be chlorinated or brominated to kill any disease carrying organisms present in the media. [0041] Moreover, the preferred embodiment of tubing 11, having micropores of 1 micron aid in preventing disease microorganisms from infecting the plants as the small size of the micropores prevents larger sized disease organisms that may be present in nutrient fluid 11a from contacting and infecting the plants. Finally, after usage, the nonwoven polymer form can be recycled to reclaim the polymer using techniques well known in the recycling arts. [0042] Synthetic plant growth medium structured as form 10 can be used not only for hydroponic plant cultivation, but also for water retention and control for rooftops, ground landscaping and for plant cultivation in developed locations such as rooftops. Figure 5 is a side view of a prior art water retention system in which a water permeable top layer enables the storage of water and its subsequent delivery to potted plants. The water is collected from such sources as rain, sprinklers and other sources in which the water contacts the permeable top layer and moves inside the top layer through capillary action.

[0043] Figure 5 is a side view of prior art water retention system 100 ("system 100") one embodiment of which is manufactured by Soleno Textiles of Laval, Quebec, Canada. Top layer 109 is water permeable, UV resistant, antirooting material with pores that allow for the movement of water from the exterior into system 100. Layer 116 is a "fluffy" less dense polymer that allows water to penetrate to denser layer 117. Dense layer 117 is designed to allow water or nutrient fluid 11a to spread evenly throughout dense layer 117. Impermeable layer 118 ("bottom layer 118") lays on the ground, pavement, or other support 119 ("support 119") and prevents any water or other aqueous liquid from passing out of system 100 through the bottom layer 118 onto support 119.

[0044] Figure 5 demonstrates how water from system 100 passes out of top layer 109 into container 112 to supply plant 114. Container 112 may be any pot, flat, or other container that includes holes that allow water or nutrient fluid 11a to move into container 112. Container 112 is seen resting on top layer 109 and crushing fluffy layer 116 to enable container 112 to contact dense layer 117. Because container 112 is in contact with dense layer 117, water or nutrient fluid 11a can pass by means of capillary action into container 112 and to the roots of plant 114. This movement of water is shown by the arrows extending from dense layer 117 to container 112. Figure 5 also demonstrates a preferred embodiment in which wall 123 extends from bottom layer 118 to top layer 109 to form a wall to divide layers 116 and 117 into separate cells or water containment areas. Walls 123 allow system 100 to overcome a slope in support 119 that would cause liquid in dense layer 117 to collect or concentrate in one area due to gravity. Another benefit of walls 123 is the prevention of the spread of disease organisms by confining them to the cell of system 100 in which they were first introduced. [0045] Figure 6 is a cross section of system 100 showing an alternate embodiment of the prior art in which drip or delivery tubes 120 are used to deliver water or nutrient fluid 11a to system 100. Liquid is passed from delivery tube 120 into fluffy layer 116 and passes into dense layer 117. Delivery tubes 120 enable the water delivered to system 100 by sprinklers, rain, or other methods to be supplemented by the purposeful delivery of liquids into system 100 where they can be made available to plants in containers. [0046] Figure 7 is a cross section of system 200 showing the improvement to the prior art system 100. Under top layer 209 is growth medium layer 210a which is adjacent to dense growth layer 210a. Both layers 210a and 210b are made from the same materials using the same method discussed above regarding form 10 and will form a recyclable synthetic plant growth medium comprising nonwoven polymer material. It will be recognized that layers 210a and 210b can be replaced by a uniform layer 210 as discussed above with form 10 and will have the same capacity to support plants and plant growth as form 10. At least one delivery tube 211 extends through or is attached to the top of the nonwoven polymer layers 210 or 210a. Delivery tubes 211 are similar if not identical to delivery tube 11 discussed above. In the embodiment shown, top layer 209 having the same UV resistant, antirooting, and water permeable properties as layer 109 discussed above, extends under layer 210 or 210b to form a second antirooting water permeable layer. It will be recognized that a layer with similar properties that is separate from top layer 209 may be utilized. Walls may be used to divide system 200 into individual cells similar to those in the prior art discussed above. [0047] In Figure 7, plants 214 are shown extending directly from system 200 without being required to be held in a permeable container. Roots 214a are shown extending through

less dense layer 210a into dense layer 210b. Top permeable layer 209 extends between dense layer 210b and fluffy layer 216, which is similar if not identical to fluffy layer 116 discussed in prior art system 100. Below fluffy layer 216 is dense layer 217, similar, if not identical in construction and properties to dense layer 117 discussed above. Bottom impermeable layer 218 ("bottom layer 218") rests on support 219 and is similar in construction and properties to bottom layer 118 discussed above. Support 219 may be the ground, a roof, greenhouse bench or other support. Top layer 209 and bottom layer 218 are preferably sealed together to form an enclosed system. [0048] Also seen in Figure 7 are one or a plurality of irrigation removal arteries 220 ("arteries 220") which extend out from layers 216 and/or 217 of system 200 individually or joined into one or more common exit. As is discussed below, system 200 comprises at least one and preferably a plurality of arteries 220 to remove accumulated depleted nutrient fluid 11a from system 200 which enables fresh or replenished nutrient fluid 11a to be fed to roots 214a. [0049] Nutrient fluid 11a is conveyed into system 200 through delivery tubes 211 and made accessible to plants 214 by passing through micropores in delivery tubes 211. Similar to form 10 above, nutrient fluid 11a will pass down to roots 214a to nourish the plants. In addition, water that is absorbed through top layer 209 is also available for plants 214. It can be seen that by inserting one or more of forms 10 into system 100 provides a combined water retention/control system 200 that can absorb excess water from such sources as rainwater and storm overflow and use it to promote plant growth. Such systems can be used for roof top gardens, greenhouses and other types of cultivation in urban or other types of developed areas. [0050] Figure 8 is a schematic representation of a recirculating irrigation system 300

("irrigation system 300") utilizing the present improvement. In Figure 8, the power source 330 is shown as a vertical axis turbine which utilizes captured wind energy to provide power to the system creating a "green" energy system. It will be recognized that other power sources, including but not limited to, connections to an electrical grid, batteries, and generator-powered motors, may also be used. In irrigation system 300, nutrient supply tank 340 is connected to irrigation mat 310, which is similar, if not identical, in construction, to system 200 discussed above. Input line 341, which may be a one or more hoses or pipes, is connected to irrigation mat 310, through growth subsystem 310a which is similar to form 10 discussed above. In one embodiment, a plurality of forms 10 may be connected as discussed above. It will be recognized that growth subsystem 310a is similar, if not identical, to growth layer 210 or a combination of growth layer 210a and dense growth layer 210b as discussed above. [0051] Output line 320 is connected to irrigation subsystem 310b which is similar, if not identical, to layers 216, 217, and 218 in system 200 discussed above. Output line 320 is

connected to arteries 220 (not shown in Figure 8) also discussed above in relation to system 200. In the embodiment shown, vacuum motor 321 powered by power source 330 removes excess water and depleted nutrient fluid 11a and directs it to pump 323 through line 322. Pump 323 pumps the water and nutrient fluid 11a to tank 340 completing the recirculation path. Pump motor 323 and vacuum motor 321 will be sized and configured according to standards recognized by those skilled in the art. It will be recognized that excess water or nutrient fluid 11a may be diverted from system 300 through drains, divert lines, and other means well known to those skilled in the art. The fluid in tank 340 may be adjusted to provide plant nutrients in proper concentrations for plants 314. It will be recognized that control systems may be utilized to measure water and nutrient quantities in irrigation mat 310 and tank 340 to automate delivery of water and nutrient to irrigation mat 310 and removal of excess water and diluted nutrients to tank 340.

[0052] Thus it is seen that the objects of the invention are efficiently obtained, although changes and modifications to the invention should be readily apparent to those having ordinary skill in the art, which changes would not depart from the spirit and scope of the invention as claimed.