WO1982002642A1

WO1982002642A1 - Hydroponic system

Info

Publication number: WO1982002642A1
Application number: PCT/DK1982/000006
Authority: WO
Inventors: Vandings Ind Aps Gartnerens
Original assignee: Pedersen Leif Liebmann
Priority date: 1981-01-30
Filing date: 1982-01-27
Publication date: 1982-08-19
Also published as: DE3231623T1; NL8220029A; ES509992A0; FR2498887A1; PT74360A; ES8302413A1; IT8267097D0; EP0072816A1; DK40881A; PT74360B; GB2106362A

Abstract

In order to be able to utilize a hydroponic system in the best possible way and at the same time to secure the best possible growing conditions for the plants, including especially the supply of oxygen to the roots in the simplest possible way, the system is built up by means of a plurality of fluid containers (1) with an overflow (2 or 17) and with an upper section (3). In this upper section (3) a nutrient substrate (4) e.g. consisting of foam can be mounted e.g. in a way to permit the formation of an air space (5) between the substrate (4) and the fluid (15). The fluid is led to the container by means of a tube (6) ending at the bottom. This secures the supply of nutrient and oxygen to the roots. To secure the outlet from the container a tube (8 or 9) is arranged that is supplied with apertures (10) at the top at an equal distance to each other. Accordingly, arches (7) with projections (11) are provided in the bottom, so that the container can be "locked" firmly to the tubes. one of the tubes (8 or 9) may further act as a drain for the fluid, which can drip from the container down into the apertures (10) of the tube, either through an external overflow (2) or through an internal overflow (16), ending in a tube stub (17) at the bottom of the container.

Description

H Y D R O P O N I C S Y S T E M

The invention relates to a hydroponic system comprising a water reservoir with a constant supply of fluid and with the possibility for a holder for plants mounted above. the reservoir.

Systems of this kind are known, but they are large, stationary plants with firm installations a.o. reservoirs. This gives a small extent of flexibility and thus a not rational utilization of an expensive system. Further these systems require control equipment to a considerable extent, these sorts of systems being very sensitive to stops in operation as e.g. stops of the pump, as the nursery beds are quickly desiccated.

It is the object of the invention to meet these problems and further to improve the growing conditions and the profitableness. This is achieved when the reservoir consists of a container which is open at the top and provided with an overflow, and with securing means for retaining the holder at a short distance above the surface of the fluid. This system makes it possible to apply an unlimited number of snail containers, which together constitute the complete hydroponic system, each container having the components that are necessary for the growing of a limited number of plants, i.e. a holder for plants e.g. in shape of a growth substrate placed at a suitable distance above the surface of the fluid in the container, and an overflow at each container.

This means that a relatively damp air flow may pass between the single oxygen-uptaking roots of the plants at the same time as the secundary roots being fed with nutrient substrate in the container. The growing conditions, especially the supply of oxygen to the roots, are the best possible. Further the formation of roots will be suitably loose so that the nutrient substrate can flow unimpededly to the roots. If the holder for plants or the nutrient substrate is in a detachable tray, it may be moved from one container to the other without difficulty.

This yields the greatest possible flexibility by the simplest possible means. Further sick plants may be easily removed, without infecting the neighbouring plants during operation. By this system it is also possible to practise rotation of several crops, and freely to remove single plants. Besides it is possible to practise continously programmed growing of plants as well as rotation, and there may be changed from one culture to another, so-called inter-cultivation, without having to switch off the system.

By using the overflow, as mentioned in claim 2, the level of fluid in the container may be adjusted easily and according to requirement, when using a longer or shorter pipe as overflow in the container.

When using a supply of fluid through a tube, as mentioned in claim 3, which tube ends at the bottom of the container, the best possible supply of nutrient and oxygen to and through the roots is secured as well as the tube may be removed easily from the container, e.g. for cleaning, and the container may be easily moved without any interference in the firm installation, as the inlet tube only has to be led down into an outlet opening.

When providing the container with a plurality of arches at the bottom, as mentioned in claim 4, each con tainer can be easily placed and fixed on a tube, which may be placed e.g. at the bottom of the greenhouse.

This tube may be provided, according to claim 5, with apertures at the top, so that the overflow from the container can run straightly down into one of the apertures. In this way the said possibility for outlet or drain through the tubes exists.

Finally it is appropriate with projections at the bottom of the container according to claim 6, so that the container may be locked in a certain position to the tube.

The invention will be further explained in the following with reference to the drawing, where

Fig. 1 is a schematic sectional view of a container, and

Fig. 2 is a sectional view through a container in use.

In Fig. 1, which is a schematic sectional view through a single container 1, one of the tubes 8 is shown that serves as an outlet for the fluid. The container 1 has a cubic content of between 5 and 10 litres. The nutrient fluid is led through a feed tube 12 to the individual containers through a flexible tube 6, which is put in over the edge of the container and down into this. In this way the fluid is admitted the container from below.

At the top there may be an overflow 2 at one side of the container, through which overflow 2 the fluid leaves the container. Further there may be mounted a frame (3) at the upper edge of the container, in which a nutrient substrate 4 can be placed. However, often it will be most appropriate and economic to use the system to so-called bare root culture without using any substrate. Between the nutrient substrate and the surface of the fluid there is an air space, where the air can move freely to and fro.

Fig. 2 shows more detailed an example of an embodiment of the system. As growing substrate 4 is shown the use of a foam block with a brittle structure, which permits the roots of the plants to penetrate. Instead of this substrate a loose substrate as e.g. sphagnum, gravel, or the like on a grating may be used. Besides a plate of e.g. polystyren can be used, which is supplied with holes, for the plant stems so that the plants can hang each in a seperate hole. This may be applied for growing tomatoes, cucumbers, green peppers, corn, vine, aubergines, and other plants. This is called a bare root system.

If a so-called watering mat is placed at the bottom of the tray, and the mat is connected to the fluid reservoir in the container by one or several wicks, plants may be grown in ordinary containers cr pots, which are placed upon the watering mat. The wick will see to the necessary oxidation of the nutrient fluid at the same time as the fluid is led up to the mat and the pots placed thereupon.

The growing substrate 4 is shown placed on a grating 13, which grating rests on the inside of the tray 3. This placing of the substrate enables an easy removal of the plants 14 from on growing container to the other.

The tray 3 rests on an internal recess at the top of the fluid container 1. The recess retains the substrate at a suitable distance 5 above the surface of the fluid so that an air space is created, where air may pass, as shown with an arrow. This oxidizes the roots in the air space or in the wick, if a wick system is applied.

In the container 1 the fluid reservoir is kept constant by means of en interior overflow 16, ending at the bottom of the container in a pipe stub 17. The fluid is led to the individual containers from a feed tube 12 via a flexible tube 6 down into the container for outlet near the bottom. The length of the overflow tube may be varied to permit change in the relation oxidation zone/water reservoir according to the actual species of plants.

The container rests on an outlet tube 8 or 9 placed in a way that permits the container to be fixed to the tube, the stub from the overflow tube being led down into the aperture 10 of the outlet pipe. Besides each container is supplied with some arches 7, which secure the possibility of placing the container on a plane surface and of fixing the container on the tube notwithstanding the placing of the container in relation to the tube. The tubes 8, 9 can be corrugated for absorption of any axial move, e.g. during variations of temperature.

The tubes 8, 9 are supplied with some apertures 10 placed at the same distance from oneanother. If the arches 7 are supplied with projections 11 placed at the same distance from oneanother as the apertures 10 each container may be "locked" to the tubes. Further these apertures can be used as outlet openings for the fluid that runs through the overflow and directly down through the openings and out into the outlet pipe 8 through the overflow tube 16. When an internal overflow is applied, a kind of indicator has to be used to show that the fluid level is kept constant.

The energy consumption of this system is very small, as the volume of water, i.e. the circulating quantity, can be varied from 0 and upwards without problems to the plants. A wick system will e.g. work very well without the need for circulation of the fluid, the water chamber serving as a water- and nutrient reservoir.

When applying the system as a bare root system, the following calculation can be made. A full-grown tomato plant requires a certain quantity of oxygen per 24 hours given that it is admitted while it is daylight. On condition of an effective flushing of the complete root system, it is considered possible that the plants can utilize the oxygen in the nutrient fluid down to 40 percent. The oxygen uptaking roots will be. a further security, but they only act satisfactorily at a 100 percentage of humidity.

By this construction it is possible to build up a plant of any size. The tube system can be used for a greater or smaller number of containers, which are only to be supplied with a tube in order to be able to work. In this way a simple, inexpensive and reliable system is achieved which yields the best possible growing conditions to the plants without the formation of algae.

The system distinguisches itself by the fact that the nutrient fluid, which is oxidized, is led to the bottom of the containers and by vertically circulation of the fluid led in between the root sections.

Claims

CL A I M S

1. Hydroponic system comprising a water reservoir with a supply pipe for fluid and with the possibility for a holder for plants mounted above the reservoir, c h a r a c t e r i z e d i n that the reservoir consists in a container (1), which is open at the top and provided with an overflow (2 or 17), and with securing means (3) for retaining the holder (4) at a short distance (5) above the surface of the fluid.

2. System according to claim 1, c h a r a c t e r i z e d i n that an overflow (16) is arranged in the container (1), this overflow ending in a pipe stub (17) at the bottom of the container.

3. System according to claim 1 and 2, c h a r a c t e r i z e d i n that the supply of fluid takes place through a tube (6) ending at the bottom of the container (1).

4. System according to claims 1 - 3, c h a r a c t e r i z e d i n that the bottom of the container (1) is provided with a plurality of arches (7) resting on an outlet pipe (8 or 9).

5. System according to claim 4, c h a r a c t e r i z e d i n that the pipes (8 or 9) are provided with apertures (10) at the upper surface permitting inlet from the overflow (2 og 17).

6. System according to claim 5, c h a r a c t e r i z e d i n that the bottom of the container (1) further is provided with a plurality of projections (11) to fit some way down into the apertures tions (11) to fit some way down into the apertures (10) of the pipe (8 or 9).