APPARATUS AND METHOD FOR HYDROPONIC CULTIVATION

Abstract: Seed is grown hydroponically by allowing them to sprout in a closed drum (1) to which water is supplied (21) and from which water can be drained at intervals such as to maintain a constant temperature in the drum (1). The drum (1) is carried on a wheeled trailer (5) and is rotatable about a substantially horizontal axis. The seed crop in the drum is oxygenated by injecting compressed air.

Description: Apparatus and method for hydroponic cultivation. This invention relates to the hydroponic production of a crop for consumption by humans or animals, from seed such as cereals (e.g. barley), grass, peas, beans, rice, maize, etc. It is known to produce crops hydroponically in a static container provided with water delivery and drainage means, and access means for the removal of cultivated seed. One such apparatus is described in the published International Application No. WO 83/0136. Such known apparatus generally requires heating means and effects slow hydroponic growth. An object of the present invention is to provide an improved apparatus for the efficient and fast hydroponic cultivation of seed. According to one aspect of the present invention there is provided apparatus for growing seed hydroponically, comprising an enclosed container having means for delivering water to the container, and access means for permitting removal of the cultivated seed from the container, and for allowing drainage of water from the container, characterised in that the container comprises a drum • mounted for rotation about a substantially horizontal axis, and provided with means for oxygenating the crop grown in the container. In use of the apparatus, the seed is first introduced into the drum. Water in an amount sufficient to cover the seed is then added to the drum, and the seed is allowed to soak. hen the seed has begun to sprout, the water is allowed to drain from the seed and carbon dioxide produced by the growing seed is vented. The seed is then allowed to grow in the drum. At periodic intervals, the growing seeds are watered by the addition of further water to the drum, water is drained from the drum and carbon dioxide vented from the drum, without allowing the seeds to soak in the water. At periodic intervals, the drum is rotated. This rotation of the drum oxygenates the growing seeds, and prevents compression of the growing seeds . The crop oxygenating means are preferably actuated at periodic intervals. Preferably, the drum is a generally cylindrical drum supported on an axle. Thus, for example, the drum may have a stub axle on each of its two end faces, the drum being supported for rotation by these two stub axles. A hatch may be provided in the cylindrical wall of the drum, for access to the drum. In use, this hatch is closed by a fora inous cover which is adatped to fit in the hatch, in a removable manner. Water and seed are added to the drum via this hatch, and the crop is removed from the drum via the hatch. Water can be drained and carbon dioxide can be vented via the hatch, with the foraminous cover in place, by orientating the drum so that the hatch is at its lowermost position. The drum, or at least those parts of it which contact the crop, is made of a material which will not contaminate the crop. Thus, for example, in the case of a crop for consumption by animals, the drum may be made of a moulded resin reinforced with glass fibre, whereas in the case of a crop for consumption by humans the drum is preferably made of stainless steel. Preferably the means for oxygenating the crop injects air, e.g. compressed air, into the crop growing in the drum and includes an air inlet extending through one of the stub axles. The drum preferably includes a means for measuring the temperature within the drum, comprising, for example, a temperature measuring probe extending through one of the stub axles. The means for delivering water to the drum preferably comprises a water pump for delivering water to a nozzle, which nozzle is disposed relative to the drum so that the drum may be oriented such that the hatch in the drum is adjacent the nozzle. If desired, two water supply means each including a pump and a nozzle may be provided, one of these water supply means having provision for heating the water. Alternatively, the water supplied to the apparatus may be heated externally of the apparatus. The apparatus preferably includes means for determining the orientation of the drum, and hence the position of the hatch. The apparatus may include a control system which controls: (i) the supply of cold water and/or heated water to the drum; (ii) the supply of air to the drum; (iii) the orientation of the drum; the control system being able to control the foregoing parameters in accordance with a programme dependent upon the temperature within the drum. According to another aspect of the present invention , there is provided a method of growing seed hydroponically, the method comprising: placing the seed within a drum adapted to be rotated about a substantially horizontal axis; sensing the temperature within the drum; supplying water to the drum with the drum in a first position; allowing the water to remain in the drum for a period which is dependent on the sensed temperature; and after said period, removing the water from the drum by causing the drum to rotate to a second position in which water can drain therefrom, whereby a substantially constant temperature may be maintained in the drum. For a better understanding of the invention, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is an elevational view of one side of an apparatus in accordance with one embodiment of the invention; Figure 2 is a rear view of the apparatus shown in Figure 1; Figure 3 is a front view of the apparatus shown in Figure 1; Figure 4 is a plan view from above of the apparatus shown in Figure 1 ; and Figure 5 is an elevational view of the other side of the apparatus shown in Figure 1. Referring to the Figures, the apparatus includes a rotatable drum 1 made of glass fibre reinforced plastics or other suitable material. The drum is made in two halves, each half being provided with flanges 2, and the flanges of the two halves being joined together to form a complete drum by means of bolting and/or bonding. The drum 1 is provided with two stub axles 3 which are fixed relative to the drum 1. The axles 3 are in turn supported by respective "A" frames 4, which in turn are supported on a wheeled trailer 5 suitable to be towed behind a tractor by means of a tow hitch 6. The front of the trailer 5 is supported by an adjustable stand 7. A guard rail 8 is fixed between the two "A" frames 4. The interior of the drum 1 is accessible via a hatch 9 in the cylindrical wall of the drum. In use of the apparatus, this hatch 9 is closed by means of a foraminous removable cover. To each half of the drum 1 there is fixed a reinforcing plate 10 to which the respective stub axle 3 is fixed, and with reinforcing members 11. The member 10 on one side of the drum is provided with eight spokes 30 (two of which are obscured by the "A" frame) which support an annular rim 31 to the outer periphery of which a sprocket chain 12 is fixed. This sprocket chain 12 engages with a sprocket wheel 32 which in turn is driven by a drive motor 13 fixed to the chassis 5 via a support 33. A roller bearing 40, held on a support 41 and bearing on the inwardly facing surface of the rim 31, serves to guide the rim 31. A cabinet or fairing 14 is provided at the front of the trailer 5, access to the interior of the fairing 14 being via a hinged cover 15. Within the fairing 14 there are disposed a battery, a pump for cold water, a pump for hot water, an air pump, various relays, and a cleaning pump. Water is pumped into the drum 1 , when the hatch 9 is at a suitable position, via nozzles 21 on the fairing 14. These nozzles are connected, via hoses, to respective ones of the pumps mentioned above, and to respective inlets 35 for cold water and for heated water. Compressed air is forced into the drum via a compressed air line which passes through one of the stub axles 3 into the interior of the drum 1 , this compressed air line being connected via an air line to the air pump. The compressed air line terminates in a probe extending into the interior of the drum. Disposed within this probe is a temperature sensor for determining the temperature within the drum. The battery 16 is trickle charged via a socket 36 to which the battery is connected. The orientation of the drum is determined by means of two micro-switches (not shown) fixed on the "A" frame adjacent the other stub axle 3. These micro-switches are activated by a pin which is eccentrically mounted upon this stub axle 3. The control system for the apparatus is contained in a console 38 and includes light emitting diode (LED) displays of which a day display displays the appropriate day in each working cycle, and the hour display displays the lapsed time in hours between different parts of the cycle as described hereinafter. The housing also carries manually operable switches in the form of buttons for actuating various programmes of operation of the hydroponic apparatus, and lamps for_ indicating operation of the pumps. The control system is used to control the hydroponic apparatus according to four programmes as described below. Programme 1 (Soaking programme) Operation of the apparatus is initiated by actuating a start button, whereupon the motor 13 commences forward drive via a relay, and the drum rotates into a first orientation. The fact that the drum is in the first orientation is sensed by the "high" sensor disposed on the axle 3, the first orientation being such that the hatch 9 in the drum is adjacent water nozzles 21. With the drum in the first position, the control system activates the cold water pump. The cold water pump then pumps a fixed quantity of cold water, for example eighty gallons, into the drum 1 during a period of approximately twenty minutes. After a further period of four hours, during which seed in the drum is soaking, the drum rotates through one and a half revolutions, ending in a second position sensed by the "low" sensor disposed adjacent the axle 3. The "low" sensor activates the drainage of water from the drum during a period (e.g. 10 minutes) set by a drain timer, after which the drum 1 returns to the first orientation to minimise heat loss through the hatch 9. The control system is such that the air temperature inside the drum is automatically monitored and controlled during the following programmes of operation of the drum. Growth of the seed in the drum generates heat which causes the air temperature in the drum to rise: it is important, to achieve an optimum growth rate, to maintain a substantially constant temperature in the drum, for example 20°C. The temperature is sensed by the temperature sensors, and subsequent operation of the apparatus is controlled accordingly. Thus, depending on the sensed temperature, the control system will control the period between successive supplies of water to the drum and, further, will determine whether the next delivery of water should be of hot or cold water. In addition, supply of compressed air to the drum is controlled in dependence on the sensed temperature. However, during programme 1 the circuitry used to monitor the sensors and emit control signals is inoperative until the hatch reaches the second position after the lapsed time of four hours as described above. Programme 2 (continues for the first two days in each cycle of operation) When a predetermined timed period has elapsed the temperature is recorded using the temperature sensors. This period is controlled by a temperature timer, in dependence on the temperature last sensed by the sensors. The temperature sensors are located approximately one inch (2.5 cm) from the end of the probe through which compressed air is injected. Depending on the sensed temperature, one of the hot and cold water pumps is actuated to pump a fixed quantity of water into the drum. For the described embodiment, this quantity is forty gallons (representing approximately half the volume of water required for soaking). The water remains in the drum for a period depending on the last sensed temperature, after which the drum completes one and half revolutions to the second position, as sensed by the low sensor, and the drain timer now starts the drain period as in programme 1 after which the drum returns to the first position. Programme 2 may commence with the pumping into the drum of 40 gallons of cold water, which remains in the drum for a five hour period before draining. For a sensed temperature of 20°C after that five hour period, hot water is pumped into the drum, remaining for six hours before draining, six hours being indicated on the control console 38. The temperature is again sensed to determine for what period the drum should next contain hot water, for example for a sensed tempeature of 18°C, the next such period would be seven hours, and for a sensed temperature of 22°C, the next such period would be five hours. Cold water is pumped into the drum between such hot water periods. During Programme 2 and the subsequent programme, Programme 3 , the air compressor is actuated once an hour for a period which is also dependent on the temperature sensed by the sensor, up to a maxiumum of 40 minutes in each hour, for example, for the temperatures referred to previously: Sensed Hot water Air compressor temperature soaking time time (minutes) (°C) (hours) 18 7 10 20 6 15 22 5 20 Programme 3 (continues during the remaining six/seven days of the cycle) The air temperature is recorded, and one of the hot and the cold water pumps is actuated depending on the predetermined periods and recorded temperatures, as described above with reference to Programme 2, to pump forty gallons of water into the drum 1. The . difference between Programmes 2 and 3 is that, after the drum has completed one and a half revolutions into the second position as detected by the low sensor, it remains in this position and does not return upright as before. The operation of the air compressor with the drum in its second position (that is with the hatch lowermost) results in efficient expulsion of carbon dioxide gas. Programme 4 When an auto-clean button is depressed, the drum 1 revolves to the first orientation to correspond with the water nozzles 21, and the cleaning pump is actuated to pump cleaning agents into the drum via spraying jets. The period over which the cleaning pump operates is approximately two minutes, as measured by a cleaning timer unit. An alarm also sounds when the voltage of a battery driving the control system drops below the required voltage. The term "hot water" used herein means water which has been heated to a temperature usually not exceeding 25°C.

Claims: CLAIMS 1. Apparatus for growing seed hydroponically comprising an enclosed container having means (21) for delivering water to the container, access means (9) for permitting removal of the cultivated seed from the container, and for allowing drainage of water from the container, characterised in that the container comprises a drum (1) mounted for rotation about a substantially horizontal axis, and is provided with means for oxygenating the crop grown in the container. 2. Apparatus according to Claim 1, characterised in that the drum (1) is cylindrical and has two end faces from which respective stub axles (3) project, the stub axles (3) being rotatably supported by respective bearing supports (4) . 3. Apparatus according to Claim 2, in which the bearing supports are carried by a wheeled trailer (5). 4. Apparatus according to any one of Claims 1 to 3 , in which the access means comprise a hatch (9) in a cylindrical wall of the drum (1) which is closed by a removable foraminous cover through which water may drain from the drum. 5. Apparatus according to any one of the preceding claims, characterised in that the oxygenating means comprise means for injecting air into the crop growing in the drum. 6. Apparatus according to Claim 2 and Claim 5, in which the air injection means include an air inlet extending into the drum through one of the stub axles (3). 7. Apparatus according to any one of the preceding claims, including means for measuring the temperature within the drum (1) . 8. Apparatus according to Claim 2 and Claim 7, in which the temperature measuring means include a probe extending through one of the stub axles. 9. Apparatus according to Claim 4, in which the means for delivering water include a nozzle so positioned that the hatch in the drum may be disposed adjacent the nozzle by suitable orientation of the drum (1). 10. Apparatus according to Claim 5, having two said water supply means, each comprising a pump and a nozzle, one of which includes means for heating the water. 11. Apparatus according to Claim 4 or Claim 9, including means for determining the orientation of the drum, and hence the position of the hatch (9). 12. Apparatus according to any one of the preceding claims, including a control system which controls: (i) the supply of cold and/or heated water to the drum; (ii) the supply of air to the drum through the oxygenating means, and (iii) the orientation of the drum, in accordance with a programme which is dependent upon the temperature within the drum. 13. A method of growing seed hydroponically in a container (1) to which water is supplied and from which water may be drained, characterised in that the method comprises the steps of: placing the seed in the container, which is in the form of a drum (1) rotatable about a substantially horizontal axis; sensing the temperature within the drum (1) ; supplying water to the drum ( 1 ) with the drum in a first orientation, the water remaining in the drum (1) for a soak period which is dependent upon the sensed temperature, and after the said period, removing the water from the drum (1) by rotating the drum to a second orientation in which the water drains from the drum, whereby a substantially constant temperature is maintained in the drum. 14. A method according to Claim 13, in which the temperature in the drum is maintained in the range 18°C to 22°C. 15. A method according to Claim 13 or Claim 14, characterised in that the temperature of the water supplied to the drum is selected or regulated according to the temperature to be maintained in the drum. 16. A method according to any one of Claims 13 to 15, characterised in that the seed growth takes place over a period of several days during which the temperature in the drum (1) is maintained substantially constant in successive soak periods by draining water from and supplying water to the drum, and in that, during at least some of the said soak periods, compressed air is delivered to the drum to oxygenate the crop. 17. A method according to Claim 16, in which compressed air is delivered to the drum for a period of time dependent upon the sensed temperature but not exceeding 40 minutes per hour. 18. A method according to Claim 16, characterised in that the seed growth period is followed by a stage during which carbon dioxide is expelled from the drum by delivering compressed air to the drum with the latter in its second orientation.

Inventors: TODD ANTHONY JOHN, TUCKER LESLIE ROBERT, TUCKER ROBIN, TODD, ANTHONY, JOHN, TUCKER, LESLIE, ROBERT, TUCKER, ROBIN
Applicants: SEDGEMOOR HYDROPONIC SYSTEMS L, SEDGEMOOR HYDROPONIC SYSTEMS LIMITED
Application year: 1985
Main classification: A01G31
IPC codes: A01C1, A01G31