EP0008289A1

EP0008289A1 - Aeration and nutrient intermix hydroponics

Info

Publication number: EP0008289A1
Application number: EP79900047A
Authority: EP
Inventors: Kenneth Roy Dunn
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-01-05
Filing date: 1979-07-31
Publication date: 1980-02-20
Also published as: DE2953945A1; FR2500720B1; CH644490A5; WO1979000480A1; FR2500720A1

Abstract

Le dispositif comprend des moyens pour faire varier de facon continue ou pour arreter le debit du liquide s'ecoulant vers les canaux individuels (4) dans les cultures hydroponiques et des moyens pour faire varier le niveau du liquide dans chaque canal tout en produisant automatiquement une aeration complete et un melange complet du liquide avec les substances nutritives. De plus, la place disponible a l'interieur d'un canal hydroponique est augmentee grace a un support de plant demontable qui permet une preadaptation continue de la distance entre les plants en croissance dans un canal sans risque d'endommagement tout en fournissant une couverture du canal pour empecher l'entree de la lumiere ou de substances suspendues dans l'air. Le support de plant comprend des moyens supplementaires permettant de fixer ou d'enlever des plants sans risque de dommage aux feuilles ou a la racine, et des moyens permettant la fixation d'un barrage lorsque le canal est incline ou comporte une chute trop importante.The device comprises means for continuously varying or for stopping the flow of the liquid flowing to the individual channels (4) in hydroponic cultures and means for varying the level of the liquid in each channel while automatically producing a complete ventilation and complete mixing of the liquid with the nutrients. In addition, the space available inside a hydroponic channel is increased thanks to a removable plant support which allows a continuous pre-adaptation of the distance between the growing plants in a channel without risk of damage while providing cover. of the channel to prevent the entry of light or substances suspended in the air. The plant support includes additional means for fixing or removing plants without risk of damage to the leaves or the root, and means for fixing a dam when the channel is inclined or has too great a fall.

Description

TECHNICAL FIELD:

This invention relates to the growing of plants of all types and varieties in the manner known as soilless cultiv3.tion, also referred to as hydroponics. BACKGROUND ART:

There are three main forms of soilless cultivation:-

1. Gravel Culture - wherein a gravel or sand/gravel mixture is retained within walls on a firm base or in a lined pit. Irrigation is provided by flushing the gravel with water which can contain nutrients, or the nutrients are sprinkled onto the surface of the gravel. Alternatively, vermiculite or perlite, or some other subsrate is used instead of the gravel.

The irrigation liquid is used with the frequency required by the growth of the plants and the climate, and is either returned to a reservoir via a pump, or is allowd to drain away on a total loss system.

This field of soilless cultivation is the subject of articles and books by Sholto Douglas (India and the United Kingdom), and do not in any way conflict with, or bear any similarity tσ the invention later described.

2. Nutrient Film Technique - wherein a seedling or plant is transferred to a plastic channel of thin material, the top edges of which are folded up to constrain the stem of the plant and then held in place by clips. Liquid containing nutrients are re-circulated into and around the channels through thin pipes, the bore of which in relation to the pressure rating of the pump regulates the flow rate of the liquid into the channels. The maximum depth of the liquid in the channel is 1mm.

Dr. Alan Cooper (United Kingdom) has produced books and articles on this subject, and is the named inventor of British Patent Number 1,245,581, the title of which is 'Cultivation, of Plants'. J. Deep Water Culture - a re-circulatory system where the liquid exceeds 1mm in depth, and has in the past required the transfer of a plant to the channel, a method of germinating seedilngs for retention in the channel is the subject of a British Complete Specification by the applicant. Past work has been that of Dr W.F. Gericke (United States of America), and more recently by P. Van Lune and B. J. Van Goor at the Institute for Soil Fertility, Karen, The Netherlands. The use of deep water culture for other than Research and Development work has been restricted in the same way as item 2. Nutrient Film Technique insomuch that the main development has been on the nutrients rather than the equipment. It is in this field that the invention is related. DISCLOSURE OF INVENTION:

A hand fabricated development system was exhibited at The British Growers Look Ahead Exhibition in Harrogate, Yorkshire, England, on the 1st March 1977. the equipment disclosed a method of germination of plants from seed by use of cylindrical containers from which a capilliary wick projected into the liquid in the channel. The container being retained above the liquid by a twin mesh having side rails which rested on the edge of the channel. The system shown could also be seen to require a re-circulatory pump and sump but this was not exhibited, nor were the innovations which are the subject of this application. The leaflets provided to the trade visitors showed the wire mesh and seed germination method but disclosed no other characterization. Provisional patents taken out by the applicant during 1976 and 1977 are the subject of the complete specification now being examined. Further provisional patent applications were made on the $th January 1978 covering the characterizations of this application, prior to exhibiting a prototype of the production system at The British Growers Look Ahead Exhibition on 21st February 1978. The provision of leaflets for the general and trade enquiries at the time and since has disclosed the properties of the technique, and characterizes the principles. First issue of this information was February 1978.

The system was again displayed at the Europlεgtique Exhibition, Port de Versailles, Paris, France in June 1S78, and leaflets were distributed to visitors from many parts of the world. There have been numerous enquiries for information from the disclosure of information in the press, all of which have been supplied with leaflets depicting the invention. These again have been post February

1978.

BEST MODE FOR CARRYING OUT THE INVENTION:

The invention is a series of innovations which ideally group together as as a unity of invention, but which may under certain circumstances be used independently.

1. The Gravity Feed Bar (1), a closed container having an inlet point through which the liquid is fed to the Gravity Feed Bar from the pump (2), or from a reservoir situated at a level higher than that of the Gravity Feed Bar; An outlet or outlets (3) shown in the diagram as valved, which supplies liquid from the Gravity Feed'Bar to the channel or channels (4 ) ; and an overspill cascade outlet (5), for the return to the sump (15) of excess liquid provided to the Gravity Feed Bar by the pump which is rated to provide a greater rate of flow to the Gravity Feed Bar than is required to be transferred to the channel or channels through the valved outlets.

The valves may be replaced by any means of flow restfictor, and the Gravity Feed Bar may be in any position above the channel. The purpose of the Gravity Feed Bar is to provide a constant 'head' of liquid to the valves thus ensuring a regulated flow of liquid to the channels; and, from the overspill cascade to provide an escape for the excessive input from the pump to the Gravity Feed Bar which produces an aeration of the liquid during the overspill and in the cascade return to the sump. Additionally, this cascading at Gravity Feed Bar, in the return pipes, and at the sump, provides a complete re-mixing of the nutrient chemicals within the liquid from which the plants feed, thus ensuring that on displacement into the channel the dangers of imbalance in nutrient strengths is appreciably minimised.

2. Inlet Baffle (6), against which the liquid from the valve is projected into the channel, creating another aeration and nutrient intermix, and by the displacement of the baffle at an angle projects the liquid to the rear of the channel and against the channel end cap in such a way that the spray effect produced creates a fast moving film on the surface of the liquid in the channel, the hydraulic drag of which tumbles the freshly aerated film into the underneath layers of the liquid within the channel to remove stagnated areas in and around the plant roots, passing the stale liquid towards the outlet end of the channel. 3. Outlet/Level Setting Pipe (7), at the exit of the channel providing, through a hole, or holes, a means by which the surplus liquid in the channel passes back through piping to the sump. Alternatively to the holes (8) the pipe may be shortened to permit escape over the top of the pipe. The pipe is connected through the channel by a seal (14), and, when moved vertically through the seal, can determine the depth of the liquid within the channel. Removal of the pipe from the seal in the channel permits the channel to be emptied of liquid for flushing and cleaning with the plants remaining in situ. Narrow slots (9) can be cut into the Outlet/Level Setting Pipe, below the main liquid exit orifice to permit exit of the lower levels of the liquid within the channel at a rate flower than that of the inlet and main outlet. The slots can be displaced inany way convenient or desired, and in any size or number found to be suitable for the purpose intended. The size of the Outlet/Level Setting Pipe is such that further cascade and nutrient intermixing takes place during the exit of the liquid from the channel through the orifice, and again when returning to the sump and falling onto the surface of the liquid within the sump. 4. Demountable Plant Carrier (10), having, by the design of the side sections, the facility to be clipped onto the top of the channel walls across the channel. The clipping protrusions on the side section may be so displaced as to allow the Plant Carrier to be inverted (11) so permitting the relationship between the base of the Plant Carrier and the surface of the liquid in the channel to be reduced or increased independently of the other Plant Carriers on the same channel. Furthermore, the Plant Carrier has one inner section which is removable (12, permitting the Plant Carrier to be opened to facilitate to installation or removal of a plant from the Plant Carrier whether or not the plant is retained in a separate plant container, such a removal or installation will not damage the root or foliage of the plant. A clip, bolt, or other form of retaining method may be used to secure the removable section of the Plant Carrier to the main body, against unintentional separation.

The side rail of the Plant Carrier, having an opening to the top at the side whichever way the Plant Carrier is affixed to the channel will allow the fitting and securing (13) of a material (16) ideally a soft plastic, which can similarly be connected to an adjacent Plant

Carrier. The softness of the material will allow a concertina effect (25) permitting the Plant Carriers to be moved along the channel in relationship to each other to change the spacing between any or all of the Plant Carriers according to the size and space requirement of the plant held in the Plant Carrier.

The material will additionally protect the interior of the channel from entry of extraneous matter, and, in hot climates, reduce the evaporation rate of the liquid within the channel. At the inlet and/or outlet ends of the channel, where a Plant Carrier is not acting as a closure of the top of the channel, the material can be ensure surface closure.

Whilst an open topped channel is described and depicted, the innovatory principles apply to any formation of material or materials capable of conveying the liquid and maybe closed, as is a pipe (17) or other sections some of which are depicted as at (l8);(l9); and (20);.

Where a cutout (21) is made in a pipe or tube, distance between the plant carriers will be determined by the spacing of the cutout.

Alternatively, a top cover may be provided (22) for protection of the channel where the distance between the plant carriers is then determined by the length of the cover. Variation of the distances between plant carriers will be then determined by the change of length of the covers.

Where it is required that a channel or pipe is to be installed on, or with, a gradient (23), the plant carrier can have the addition of a tongue projecting to the underside (24) which may be permanently fixed or located between the two members of the plant carrier (10) and (11) in such a manner as to allow transfer to either face when the plant carrier is inverted. The projection, hereinafter referred to ae the Weir, only partially closes the channel or tube to permit the liquid within the channel or tube to pass over the upper face of the Weir at the point of, or adjacent to the plant roots.

This provides further aeration whilst ensuring that each plant has depth of liquid and nutrient available at the roots. A further advantage is the avoidance of flooding to the plant or overspill from the plant carrier orifices at the lower gradient points of the channel or pipe.

With the ingress of liquid from the valve at the inlet end of the channel or pipe, liquid will pass from section to section and eventually to the outlet pipe with eventual return to the sump. The Weir blade may be solid, or perforated, and does not of necessity need to be a tight fit into the channel or pipe.

In certain circumstances, such as the growing of root crops or bulbs, the Weir or a suitable gauze at the plant carrier or at any point along the channel or pipe associated or disassociated with the Weir, will act as a barrier to retain a substrate within which the root crop or bulb will grow. The aeration and nutrient intermxing will not be affected by the intermittent flow operated by the closing and opening of the valve or valves at suitable intervals, insomuch that the pumping of liquid to the Gravity Feed Bar, or supply from a header tank continuing overspill cascade back to the sump may be continued with the valve or valves opened or closed as part of a shortened cycle of operation without detriment to the function of the equipment.

The demand for non soil facilities for growing plants, especially food plants, is increasing at a rate proportionate to the population increase in the world especially in emerging countries whose climatic or soil conditions are not suited to the standard horticultural and agricultural methods.

Furthermore, there is the necessity to conserve resources of water, energy, and also the chemicals used for plant nutrition whether organic or inorganic. The ability of nations to adequately feed their populations is paramount if there is to be an avoidance of conflict for territorial rights. These factors alone direct that there is a demand for commercially viable non soil techniques which in the past have not been forthcoming. Additional applications are for Research and Development throughout the world, and those of education.

The provision of full aeration has only in the recent years been appreciated as vital for plant wellbeing. Similarly the continuing intermixing of nutrients within a hydroponics system is now seen to be a requirement. Neither of which have been previously acheivable without ancilliary equipment.

The innovations at 1., 2., and 3., provide these two vital factors in a hydroponics system automatically as an inherent part of the technique, and each innovation will provide an independent facility. The industrial application is simply that the provision of these innovations has permitted the introduction of commercially viable soilless cultivation.

The innovation at 4. extends the use and applications of 1., 2., and 3. by making the best possible use of the space provided in the channel to suit differing growth rates of plants and different types and sizes of plants. Making the system more flexible whilst reducing the demand on resources.

Claims

1. A method of providing fully aerated and re-cycleable liquid for growing plants without soil (hydroponically).

2. To the liquid can be added nutrients, which the system continually intermixes whilst the aeration takes place.

3. An apparatus for providing aeration and/or nutrient intermixing which is either an integral part of the system or which can be used independently.

4. A means of maintaining a deep liquid level at a series of points along a channel or pipe by the provision of a Weir under or adjacent to the plant.

5. Apparatus to permit the introduction of a seedling or grown plant into the system which avoides damage to the plant, root or foliage. The apparatus having capability of being split accross or in the same direction as the channel or pipe to facilitate the said introduction of seedling or plant.

6. A means of retaining a substrate within the channel or pipe to permit the growing of root crops or bulbs, which does not interfere the functioning of the apparatus to provide fully aerated and re-cyclable liquid which may or may not have nutrient added.

7. A means of providing an outlet for the channel or pipe to dispose of the liquid entering via the inlet valve, which by virtue of design also acts as a method of readily adjusting the depth of the liquid within the channel or pipe, and by virtue of the removability of the outlet tube permits the channel or pipe to be drained of liquid without the removal of the plants to facilitate the cleaning of the channel or pipe.

The fitment of the adjustable rate flow valve permits the opening of this valve to provide a high density flooding along the channel or pipe when the outlet tube is removed for full flushing purposes.

8. The provision of a valve or valves to individual channels or groups of channels provides the facility to regulate or cease the flow to individual channels or groups of channels independently of the functioning of and rates of flow to, other channels. The term channels also refers to pipes and tubes.

9. The apparatus, or any part thereof, is not restricted to the soilless growing of plants, but is equally suiatble for other purpose where aeration and other controls are required, including the breeding and raising of fish and other water animals. Temperature controls then being provided by integral or independent systems, if required.