GB2050788A - Improvements in or relating to nutrient film horticulture - Google Patents

Abstract

A bed for the cultivation of plants in a flowing nutrient comprises lengths of gulley 15 detachably joined together and preferably thermally insulated from the ground. The gullies may be enclosed in a flexible sleeve 13 held up by hoops 14 and the sleeves may be arranged side by side and connected at their ends to manifolds for circulation of nutrient and/or a chosen atmosphere, Figure 1 (not shown). <IMAGE>

Description

SPECIFICATION Improvements in or relating to nutrient film horticulture The present invention relates to developments of the form of hydroponics known as the Nutrient Film Technique in which plants are grown in gulleys along which a continuous film of liquid nutrient is caused to flow, the plant roots developing in the gulleys to form mat like formations along the gulley bottom.

One object of the invention is to provide a controllable growth enviroment for plants in a Nutrient Film Technique media, which would allow plant culture in almost any climatic situation and would provide, on an agricultural scale, a degree of enviromental control normally associated with horticultural practice.

According to one aspect of the invention there is provided a culture bed in the form of a length of gulley formed, for example, of plastic, metal or other impermeable material or a composite material, layed end to end and joined together either permanently by bonding with heat or adhesive or by clipping together in such a way as to provide a watertight seal and dissassembled when required.

Preferably such guileys may be insulated from ground temperature diferential by their insulated composition or insulating material fixed or bonded to the underside of the gulleys.

Preferably at various spacing along such interconnected gulleys are circular extensions, strips or wires of suitable material, preferably flexible but able to spring back into their original and natural circular position, fixed to as part of the gulley, or otherwise attached to the gulley in such a way as to make hoops of a particular diameter above the gulleys. In one form, these spring hoop strips or wires are bent into a reduced diameter hoop above the gulley by means of sliding clips or other locking means, and when released, spring outward to form their natural circular position of wider diameter and held firmly in this position by re-positioning the sliding clips or by other means.

Preferably each length of such gulley, either before the gulleys are joined together in one continuous length or afterward, is positioned within a tubular sleeve of transparent or opaque flexible and impermeable material such as polythene, the diameter of the tubular sleeve depending upon the type of crop to be grown within it and of the same total diameter as the supporting gulley hoops in their extended position. The gulley hoops in their suspended position serve to support the "bio-sleeve" in a tubular form, though this is not the prime function of the gulley hoops except during the harvesting operation; at other times air inflation maintains the "bio-sleeve" in tubular form.

In another aspect of the invention, the tubular sleeve can be composed of rigid transparent or opaque plastics material, which form dispenses with the need for gulley hoops or gulleys, the bottom of the rigid tube being sloped if required to serve as an integral gulley with the inherent rigidity of the tube providing the formation otherwise performed by gulley hoops.

A "Flowline" (as described in British Patent Application No. 44453/76, a copy of the Complete Specification of which is attached hereto as an appendix) suitable for the type of crop to be grown, is preferably layed along the whole length of the interconnected gulley bottom. The flowline, if preferred, may embody a flexible cord of desired shape and material, either in the form of a flat strip of strong gauze web construction, carrying on or within it an electrical resistance heating wire and/or if desired, a tube provided with outward facing apertures, which may be used to conduct and supply liquids to plants growing along the length of the gulley.The form of the "Flowline" may be such that plant seedlings grown on, for example, blocks of rock wool or similar material or any other suitable seedling block material, may be attached to the flowline by staples, adhesive, engaging male/female interfaces, or by any other method. Seed may also if required, be attached to the Flowline as described in Patent Reg. 44453/76.

For certain types of crops and requirements, a series of flowlines either separately or interconnected may be used in each gulley in preference to a single flowline. A flowline may also take the form of a casing, taking the shape of the bio gulley and fitting into it along its length.

In use, a length of such transparent or opaque tubular sleeve containing interconnected gulleys complete with the appropriate Flowline, is layed on inclined land or other support with sufficient gradient so that liquid may run gravitationally from end to end within the gulley or rigid bio-tube bottom.

The soil on which the bio-sleeve is layed may itself be formed into a gulley shape by mechanical means, so that the bio-sleeve gulley or tube may fit into and be supported by such soil shape. If required soil can be formed into permanent shape by means of stabilisation, involving the admixture of lime or cement or other additives or by applying materials such as latex to the formed soil surface.

A plurality of bio-sleeves or tubes can be layed in this manner side by side so that the sleeve sides of each tube are touching, thus reducing the area of the tube exposed directly to outside air temperature and air movement to the top surface of the bio-sleeve.

Inflation of the bio-sleeve would serve to further amplify this objective.

A multiplicity of bio-sleeves layed side by side in this way together, may be anchored to the ground by a band of desirable shape and width and of any suitable material, layed over the battery of biosleeves and across their total width at the points where the gulley sleeve support hoops are aligned, so that the anchoring band can lay across and be supported by the bio-sleeve hoops, with each end of the band attached to a stake so arranged by screw, corkscrew or other method, that a controlled tension can be applied to the anchoring band.

The shape in cross-section of the bio-sleeve support hoop may be a "U" type section across the width, so that the anchoring band may fit into the "U" so formed, thus serving to tension the flexible material of the bio-sleeve along its length as well as firmly locating and holding the anchoring band in place so reducing any tendency toward chaffing of the sleeve-material.

In order to provide extra insulative properties where such is-desirable, bio-sleeve anchoring bands may be bonded or otherwise affixed to a transparent or opaque flexible sheet of a shape and:size sufficient to cover a battery or series of bio-sleeves.

And further, at the pointwherethe anchoring bands attached to the sheet engage through the bio-sheet material into the "U" section form of the bio-sheet support hoop, a rubber or any other flexible or spongy material pad of suitable shape is affixed by adhesive or bonded to or fixed by any other means, tithe underside of the anchor band sheet. The height of this locating pad when in position being sufficient ta raise the covering sheet above the bio-sleeve a sufficient amount for the air space thus provided between the bio-sleeve and the sheet to produce an insulative effect, thus protecting the internal environment of the "bio-system" from extremes of solar radiation heat orcold.

The edges of the insulation sheet, complete with anchoring band tails, are secured to the ground by a system of clamps and stakes as described.

According to a further aspect of the invention, multiple bio-sleeves or tubes lying parallel and side by side on an inclined gradient, are connected together making a unified airtight system, by man ifolds at both upper and lower ends and an air circulation tube connecting both manifolds to the upper and lower parts of the system.

Such manifolds composed of any suitable material, either flexible or rigid as desired, are connected to the bio-sleeves or tubes by outlet or inlet as the case may be, internal coilars and exterior ring clamps or by any other method producing an airtight junction between bio-sleeve ends and their respec tive manifolds and providing ease of disconnection prior to harvestingorflowline recharging operations.

Apart from- maintaining airtight integrity and connecting together in a unified system the bio-sleeves in the lower part of the bio-system, the lower manifold would also serve as a collecting trough for liquid-discharging from the bio-sleeve gulleys. The lowermanifold therefore will be positioned with a slight crossfall gradientso that liquid collected within the lower manifold will run gravitationally down the manifold into a collection tank four pumping back up to the high side of the system for monitoring-asto nutrient status, recharging.with appropriate nutrient or other materials as desired, priorto recirculation within the system.

A flexible or-rigid pipe of suitable material connecting the upper and lower manifolds maintains air circulation around the system. If desired this would contain a controllable constriction which would serve to decrease the speed of air movement, increase pressure or otherwise modify the status of air-within the system. Air intake and air pressure boosting fans-togetherwith controllable air inlet and/or exit vents may be positioned within this air circulation manifold connectortube.

Powered fans for the purpose of maintaining air pressure within the system may also be sited in the upper-or lower manifolds if required, together with provision for automatic opening of vents in either manifold to control the introduction of external air should this be necessary to maintain pressure, control temperature and humidity within the system or for any other reason.

Carbon Dioxide gas or liquid, or any other gas liquid or droplet, can be introduced into either manifold or any other part of the system by suitable means.

Within this aspect of the invention air or air mixture circulation around the system would serve to transport in a well dispersed form, beneficial gases, droplets or particles throughout the biosystem. For example, the controlled introdution into the system of gases such as CO2 Nitrogen, Ethylene or any other gas, liquid or particle having beneficial effect on plant growth directly or indirectly. In a similar way, micro or molecular particles of various material such a fungicides for example, could be injected into the pressure airflow, to be circulated round the system with plants acting as an interrupting filter.

Another beneficial aspect of a degree of pressure air circulation within the bio-system would involve the moisture condensative effect on air circulating within the system, of the temperature differential between such circulating air and air outside the system conducted through these parts of the biosleeve wall exposed to outside air temperature.For example, the controlled warming of internally circulating air by applied means such as burners or other method and/or by convective warming of internally circulating air by virtue of warmed liquid running continually within the bio-sleeve gulleys either heated by electrical resistance wires also positioned within the gulleys or by heating the liquid by external means or by the nutrient solution containing residual heat, for example at night-time, nutrient water heated by solar radiation during the day and stored in a large insulated tank for use during the colder period at night. Such a heat sink, with considerably more water or nutrient solution held in insulated storage than the bio-system requires to operate functionally, would also serve to maintain cool nutrient solution circulating through the system' during the day time. Because the bio-system is a relatively closed system, water losses by evapotranspiration or evaporation would be minimal and only through circulating air vented out of the system for whatever reason. Such losses would be more than compensated for by water collection through the system acting as a condenser.

The heat sources referred to, would tend to increase the temperature differential between exterior air and air circulating within the bio-sleeves, thus increasing the systems capacity to act as a water condenser.

Condensed water generated in this way, and deposited in droplets on the inside walls of the bio-sleeves, would tend to run down the walls and in one aspect of this feature of the invention, would run directly into the bio-sleeve gulley; in a further aspect, the gulley would be so shaped that such condensed water would be able to run down past the gulley sides and then gravitationally down the length of the bio-sleeve along the bottom of the bio-sleeve itself in a space between the specially shaped gulley bottom and the bottom of the biosleeve. This water would discharge at the end of the bio-sleeve and would be collected for storage separately from nutrient solution discharging from within the bio-sleeve gulley.

The production of pure and unaltered water as a secondary by-product of the bio-system is an important consideration in the operation of the Nutrient Film Technique, for water obtained other than from distillation generally contains impurities which lead to nutrient chemical complications and also tend to build up into toxicity problems. The additional supply of water by this means, would also be of value in hot arid areas and areas with a shortage of suitable water.

In a further aspect of the invention where it is desired, for example in hot climatic areas, that air circulating within the system and the nutrient solution running in the gulleys, should be cooled and maintained at a controlled optimum plant growth temperature, excess heat from the nutrient solution be extracted and utilised by means of a heat pump or pumps, converting heat energy to a means of cooling either or both nutrient solution or circulating air. The application of such a means of conditioning or cooling circulatory air or liquid within the system, would also tend to increase within the system.

It will be appreciated that all the enviromental control, plant growth requirements and other aspects of Bio-System are ideally suited to the monitoring, operating and control by micro compu tertechnology. It is a feature of this system that all aspects of routine operation lend themselves to this form of control.

In operation the Bio-System would be charged with culture material by use of a flowline or more than one flowline in each bio-sleeve gulley as described in patent application No. 44453/76. The flowline, either charged with suitable seed attached previously at appropriate spacing along its length or alternatively, charged with crop seedlings grown elsewhere on blocks or pads of suitable material affixed by any means including those described, at appropriate spacing on the flowline at the time the flowline is being fed into the bio-sleeve gulley.

To initiate the flowline charging cycle, i.e. for the first time after laying down the system, a cord is layed within the bio-sleeve gulleys extending the whole length of the gulley. This cord is used, by attachment to a "charged" flowline fed into the bio-sleeve gulley at the high side of the system, with the cord then being pulled from the low side of inclined bio-sleeve thus pulling the "charged" flowline through the bio-sleeve gulley, so that finally the flowline is positioned along the bottom of the gulley throughout the length of the gulley. Thereafter the flowline is connected up with its culture support facilities.

Flowlines are replaced subsequently during the harvesting process, wherein a newly charged flow line is attached to the "resident" flowline at the upper end of the system and, as the resident flowline is withdrawn for harvesting, the replacement flow line complete with attached seedlings or seed re places the harvested flowline as it is withdrawn. The extracted flowline is then stored until the now resident flowline has developed mature crops ready for extractive harvesting and the cycle recommences.

The harvesting process, using industrial materials handling techniques is substantially as described in Patent No. 44453/76.

As a preliminary aid to extraction of the resident flowline on harvesting, water can be flushed down the inclined bio-sleeve gulley, thus lifting and loosening the root mat encasing the flowline from the gulley bottom so as to facilitate if such is required, the process of flowline and crop extraction.

It is therefore a feature of the bio-system, that while harvesting is in progress at the lower end ofthe inclined bio-sleeves, the system is at the same time being recharged with culture material at the high end of the bio-sleeves by virtue of the interlinking resident and replacement flowlines.

With harvesting and therefore recharging completed, the bio-sleeves are re-attached to their respective manifold inlets and outlets, the system switched on and the growth cycle recommences.

In order to promote a fuller understanding of the above and other aspects of the present invention,-an embodiment of various aspects of the invention will now be described, by way of example only, with reference to the accompanying drawings in which; Figure 1 is a schematic perspective view of a series of plastics tubes arranged over sloping ground with flowlines therein, and Figure 2 shows in schematic perspective various detail aspects of the arrangement of Figure 1.

The arrangement in Figure 1 shows a number of plastics tubes or sleeves 10 arranged over a piece of sloping ground between an upper manifold 11 and a lower manifold 12. Each ofthetubes 10 is arranged as shown in Figure 2a and comprises a bio-sleeve of synthetic plastics material as indicated at 13 supported on a series of extendable support hoops 14 above and around a gulley 15 for the flow of nutrient material along a flowline 16 which may be arranged in accordance with the various proposals disclosed in my Patent Application No.44453/76.

The gulley 15 may be provided with an insulating layer 17 to insulate it from the temperature of the ground, and the sleeve 13 preferably passes round the outside of both the gulley and the layer 17.

Figure 2d shows in schematic detail a crosssection of one of the hoops 14 which may be formed as a channel section with an anchoring band 18to retain the sleeve 13 in position on the hoop.

As shown in Figure 2b the gulley 15 may be provided with inwardly turned edges 19 arranged to form a passage down the outside of the gulley to a space beneath it as indicated at 20 so that water vapour condensing on the inside of the sleeve 13 may pass to the space 20 to collect therein and flow down the gradient of the gulleyto be collected.

As indicated in Figure 2c, wires 21 may be attached to the hoops 14 of a series of sleeves 10 to form a support for a flexible transparent synthetic plastics material sheet 22 to form an insulating barrier above a series of sleeves 10. Preferablythe wires 21 are spaced a short distance above the hoops 14 so that there is a space between the sheet 22 and the tops of the sleeves 10.

As best seen in Figure 1 manifold 11 is used to supply air from a blower system indicated generally at 30, the biower system preferably comprises an air inlet with a suitable electric fan arranged therein to drive air into the manifold 11, and may include an additional booster fan to provide a quick supply of airto initially inflate the sleeves 10. The manifold 11 may also include means for injecting carbon dioxide or other gases into the air for circulation through the sleeves 10. The manifolds 11 and 12 also include means for pumping, supplying, circulating and collecting the nutrient film liquid from the various gulleys 15 in the sleeves 10. The manifold 12 is also arranged to collect condensed water from the sleeves if they are arranged as shown in Figure 2b, or if they are arranged otherwise, and means is provided to store the condensed water for use subsequently. The means for circulating the nutrient film may also include means for storing the nutrient solution, and also for heating it if necessary. Such means for heating it may include a heat pump.

In a preferred arrangement air is also collected in the manifold 12 from the sleeves 10 and re-circulated to the manifold 11 through the blower system 30 through a conduit31.

Claims (21)

1. A culture bed forthe soilless culture of plants in aflowing nutrient liquid comprising lengths of flow gulley which include an impermeable material, layed end to end and joined together in such a manner as to provide a watertight seal and to allow disassembly of the lengths.

2. A culture bed as claimed in Claim 1 in which the lengths of gulley are thermally insulated from the ground.

3. A culture bed as claimed in Claim 1 or 2, in which the lengths of gulley include thermally insulat ing material in their structure.

4. A culture bed as claimed in Claim 1,2 or 3 in which the gulley is enclosed in a tubular sleeve of flexible material which is supported and spaced above the gulley by means of a series of hoops positioned at spaced points along the gulley, to enclose an atmosphere for plants to grow in.

5. A culture bed as claimed in Claim 4, in which said sleeve is of transparent ortranslucent material.

6. A culture bed as claimed in Claim 4, in which said sleeve is of opaque material.

7. Aculture bed as claimed in Claim 4,5 or 6, in which said sleeve is of impermeable material.

8. A culture bed as claimed in Claim 4,5,6 or 7, in which said sleeve is also spaced from beneath the gulley by said hoops or otherwise, to form a channel for the collection of condensed water within the sleeve.

9. A culture bed as claimed in any one of Claims 4to 8, in which said hoops are of channel shape in cross-section, and the material of the sleeve is retained in the hoops by means of a band overlying the sleeve material in the channel shape.

10. A culture bed as claimed in any one of Claims 4to 9, in which said hoops are adjustable in size.

11. A culture bed as claimed in any preceding claim, in which the gulley is provided with a flow-line running along itto guide nutrient film flow along the gulley.

12. A culture bed as claimed in Claim 11, in which the flow-line is removable in the direction of the gulley to carry with it crops of plants grown in the gulley for harvesting the crops.

13. An arrangement of culture beds comprising a plurality of beds as claimed in any one of Claims 4to 12.

14. An arrangment as claimed in Claim 13, in which each bed is laid in a shaped groove in the ground.

15. An arrangement as claimed in Claim 13 or 14, in which the sleeves of the gulley are connected at respective ends to inlet and outlet manifolds, and means is provided for circulating a chosen atmosphere through the sleeves for plant growth therein.

16. An arrangement as claimed in Claim 15, in which the manifolds include means for distributing and collecting nutrient liquid to and from the gulleys.

17. An arrangement as claimed in Claim 15 or 16, in which the outlet manifold includes means for collecting water condensed in the sleeves separately from nutrient liquid.

18. An arrangement as claimed in any one of Claims 15, 16 or 17, in which the circulating means includes means for maintaining the pressure in the sleeves above ambient pressure.

19. An arrangement as claimed in any one of Claims 15, 16, 17 or 18, in which the circulating means includes provision forthe injection of gas other than air, or a liquid to the atmosphere in the sleeves.

20. An arrangement as claimed in any of Claims 13 to 19 including means to selectively heat the atmosphere in the sleeves during plant growth.

21. A gulley or arrangement of gulleyforthe soilless culture of plants substantially as herein described with reference to the accompanying draw ings.