WO2003041489A1

WO2003041489A1 - Cultivation system for crops

Info

Publication number: WO2003041489A1
Application number: PCT/NL2001/000830
Authority: WO
Inventors: Abraham Wilhelmus Brandon
Original assignee: Landers, Andries, Hendrik
Priority date: 2001-11-15
Filing date: 2001-11-15
Publication date: 2003-05-22
Also published as: EP1448046A1

Abstract

A system for cultivating at least one crop comprises a number of displaceable crop carriers (20) for receiving the crop thereon and a transport system for transporting the carriers through the system (10) during the growth of the crop. The transport system is herein adapted to transport the crop carriers, at least during operation, in stepwise manner at least substantially one after another through the system. Fully continuous cultivation of the crops is thus achieved, wherein the crop carriers are transported serially through the system, and can be harvested at a fixed interval after passing through the transport route.

Description

Cultivation system for crops

The present invention relates to a system for cultivating at least one crop, comprising a number of displaceable crop carriers for receiving the crop thereon and a transport system for transporting the carriers through the system during the growth of the crop.

In more traditional glass horticulture use is made of standing glass, such as greenhouses and glasshouses, the floor area of which is utilized to cultivate crops. The advantage of such a substantially closed environment is that a conditioned climate can be provided for the crop which is optimally adapted to the growth conditions for the crop in question.

Cultivation is thus generally possible throughout the year, i.e. irrespective of season, while outdoor cultivation, where this occurs, is possible for only a part of the year. A drawback of glass horticulture however is formed by the cost of maintaining the desired growth climate, and more particularly the fuel costs. In order to reduce these costs per unit of crop, recourse is had to the greatest possible degree of utilization of the culture substrate, which however has the drawback that the accessibility of the crops is adversely affected thereby. This drawback is particularly apparent during sowing, maintenance and harvesting of the crop, wherein workers and/or machines must be taken to the crop to carry out the required operations.

In order to obviate this latter problem, systems also exist wherein cultivation takes place on a displaceable culture substrate and wherein the system is provided with a transport system to transport the culture substrate to a sewing or harvesting station instead of vice versa. In this case cultivation can take place at very close mutual proximity and even at multiple levels in a building, since access to workers and/or machines has to be provided only at specific locations to which the crop is then transported as required, while this access is no longer necessary at the growing location. In the case of fertilizing, humidifying and spraying of the crop, this can take place in both situations via an optionally separate pipe network, so that the crop does not need to be accessible anyway by machines and workers for this purpose. An example of such a cultivation system provided with a transport system is described in the American patent no. 4,068,405, while in European patent application no. EP 142.643 use is also made of a transportable culture substrate. In both cases cultivation takes place at multiple levels in a building, wherein separate crop carriers with the crop thereon are suspended from a continuous chain system respectively lie on a conveyor belt and transport system to enable transport thereof through the building.

A difference between these two known cultivation systems with a transport system for a displaceable culture substrate is that in the American patent no. 4,068,405 a transport system is used with which the crop carriers are guided serially at a more or less continuous speed through the system, while the cultivation system described in European patent application no. EP 142.643 comprises a relatively complicated transport system with which the crop carriers are randomly accessible and transportable. Both cultivation systems thereby have their own drawbacks. The cultivation system of the American patent, although relatively simple and therefore not so expensive, is for instance comparatively inflexible in the sense that when there is a problem with one of the many crop carriers the whole transport system has to be shut down to deal with the problem. Conversely, the cultivation system known from the European patent application is particularly flexible and adaptable, but so complicated that it is doubtful whether such a system could ever be put into practice in economically responsible manner.

The present invention has for its object to provide a cultivation system of the type stated in the preamble which does not have these drawbacks, or at least does so to a lesser extent.

In order to achieve the intended objective, a system of the type stated in the preamble has the feature according to the invention that the transport system is adapted to transport the crop carriers, at least during operation, in stepwise manner at least substantially one after another through the system. The system according to the invention herein makes use of serial transport of diverse crop carriers, wherein the crop carriers are transported in an optionally imaginary circuit, so that the transport means can remain relatively simple. Other than the system according to the above mentioned American patent, the transport means provide not a continuous but a stepwise transport of the crop carriers. In the interval between successive steps the crop carriers are hereby available for maintenance, service and the like, without this necessarily affecting the progress of the other crop carriers. A specific crop carrier can thus be removed from a series of crop carriers during this interval, for instance if a disease or other interruption of growth of the crop present thereon is established. The other crop carriers herein continue undisturbed along their predetermined path.

In a particular embodiment the system according to the invention is characterized in that the transport system transports the crop carriers through the system in steps of Δx centimetres at an interval of Δt seconds, and that Δx and Δt are chosen such that a crop carrier has a residence time in the system which at least practically corresponds with a desired cultivation period of the crop. The residence time of the crop carrier in the system is thus adjusted to the growing period of the crop. At a beginning of a route covered by the crop carrier in the system the crop is for instance sowed, whereafter the crop, finally full-grown, can be harvested at an end of the route. Because use is made of serial transport, this then continues constantly, so that after every Δt seconds a subsequent crop carrier with crop can be harvested. A practical embodiment of the system according to the invention is characterized more particularly herein in that Δx is in the order of magnitude of 20 centimetres and Δt is in the order of magnitude of 36 seconds, so that a full crop carrier of a length of 2 metres can be harvested every 6 minutes.

A particular embodiment of the system according to the invention has the feature that the system comprises an entrance and an exit for crop carriers, between which there extends a route distributed over a number of mutually adjacent transport paths. Such a configuration is of particular advantage in a system of substantially rectangular lay-out, wherein the transport route meanders from an entrance close to one of the corner points to an exit close to one of the other corner points. An exceptionally high degree of utilization can thus be realized. A particularly flexible system is obtained in a preferred embodiment of the system according to the invention characterized in that the system comprises one or more intermediate exits within the route. The presence of intermediate exits provides the option, among others, of discharging crop carriers early if the crop thereon is already full-grown before it reaches the exit of the system. With a view hereto, the system can for instance be embodied such that, from the halfway stage of the maximum cultivation period, an intermediate exit is for instance available about every week, so that the cultivation period can be shortened on a weekly basis. The system is thus also suitable for mixed cultivation of crops with mutually differing cultivation periods. In addition, the intermediate exits can be used for service and maintenance or, in the case of calamities, to quickly remove and discharge a crop carrier somewhere in the circuit.

From a logistic viewpoint it is recommended herein that the system according to the invention be characterized in that at least some of the intermediate exits are situated at an end of the transport paths. The crop carriers for removal can in that case leave the relevant part of the system directly via an intermediate exit in order to be discharged for instance round the outside via a rapid transport system. The intermediate exits moreover provide the option of shortening the residence time of crop carriers in the system, which may be desirable for crops with a shorter cultivation period than other crops in the system. Crops with differing cultivation period can hereby be cultivated simultaneously in the system.

The system according to the invention is not only suitable for the cultivation of one variety of crop, but provides the option of cultivating a plurality of crop varieties simultaneously and even mixed together. So as to have a constant overview of the growth process and to know with which crop a crop carrier is filled, a further embodiment of the system according to the invention has the feature that at least substantially every crop carrier is provided with unique identification means. These latter can herein be of many kinds varying from text, an image, a bar code and the like to electronic identification means such as an optionally remotely electronically readable memory chip.

Otherwise than in conventional glass horticulture, the crop in a crop carrier is preferably subjected to a growth climate individually adapted thereto. A preferred embodiment of the system according to the invention therefore has the feature that growth control means are provided to influence a growth climate per crop carrier on the basis of the identification means of the crop carrier and the position of the growth control means in a transport route of the crop carrier. It is possible to determine on the basis of the identification means which specific crop is situated in the crop carrier, while the position of the growth control means determines which part of a growth program will be provided for that crop.

In a further embodiment the system according to the invention is characterized herein in that the growth control means comprise means from a group of lighting means, heating means, fertilizing means and humidifying means. Because the crop is constantly in movement and is thus guided slowly but surely to the growth control means, the position of the growth control means corresponds to a determined moment in the cultivation cycle of the crop. The growth control means can be operated to cause a cultivation cycle to progress optimally, taking into account for instance day and night changes. It is thus possible to attempt to simulate the ideal growing conditions for each crop so as to achieve the highest possible yield and crop quality.

In a further embodiment the system according to the invention is characterized in that the lighting means are capable of a variable spectrum adapted to the crop. Crops have been found to be not only sensitive to the amount of light provided but also to the spectrum of the light. This differs however from variety to variety. By thus making use according to the invention of lighting means with a variable emission spectrum, it is possible to seek the best possible tuning of the ideal spectrum for a determined crop variety. A further embodiment of the system according to the invention has more particularly in this respect the feature that the lighting means comprise a system of mutually differing light-emitting diodes which can be individually controlled, optionally in group-wise manner. Light- emitting diodes, or LEDs as they are normally referred to, radiate light in a specific wave range. They do this in a particularly efficient manner, so that the light output per unit of power consumption is high and the heat production relatively low. By combining different types of LED in the lighting means, and particularly LEDs in the primary colours, the ideal spectrum for the crop can be at least approximated by selective control of individual LEDs or groups of LEDs.

In order to also individually control the ambient temperature of the crop, a further particular embodiment of the system according to the invention has the feature that the heating means comprise one or more radiant heaters. Radiant heaters provide a relatively directional and direct heating, so that a crop carrier can thus be brought to a temperature therewith which differs from the temperature of another, for instance subsequent crop carrier with crops. An individual heat management can thus be provided per crop carrier.

A large number of heat sources, lighting means, irrigation means and other growth control means will in practice be disposed as stations along the route of the crop carriers. Recourse could be had for control of these stations to a heavy central processing unit from which the whole process is controlled. However, a preferred embodiment of the system according to the invention has the feature that the growth control means comprise diverse stations in the system which can each be at least substantially autonomously controlled by their own central processing unit. This has the advantage that it is possible on the one hand to suffice with a processing unit which is relatively simple, and therefore not very expensive and not very susceptible to malfunction, while on the other hand, in the case a malfunction were to occur in the processing unit, only the stations controlled thereby would possibly not function correctly, and the process would otherwise continue normally.

A further embodiment of the system according to the invention has in this respect the feature that the identification means provide an indication of the nature of the crop in crop carrier provided therewith. This data is sufficient information for the station to enable precisely the correct climate to be provided. The location of the station is in any case a constant, so that the nature of the crop is the only other factor which decides the climate which will be provided. The central processing unit can be linked for this purpose to a file optionally structured as a database in which the desired treatment is stored for any relevant variety of crop.

So as to make sure that the climate provided to the crop on a crop carrier is disrupted as little as possible by a growth climate elsewhere in the system, a preferred embodiment of the system according to the invention has the feature that along the transport route for the crop carriers are arranged climate separating means which are able to create a barrier between growth climates prevailing on either side thereof. This embodiment is herein based on the insight that, certainly in the case of the same variety of crop, the climate between successive crop carriers in a row will generally not vary much, while the difference from row to row can on the contrary be large because in a direction transversely of a row adjacent crop carriers may have a relatively great difference in residence time in the system.

In order to limit as far as possible the gradient of different ambient parameters such as temperature, air humidity and lighting in a direction transversely of a row direction, a further embodiment of the system according to the invention has the feature that crop carriers follow a route which meanders over a number of substantially parallel rows and that the row length and transport speed are adapted to each other such that corresponding crop carriers in adjacent rows run at least practically in phase with each other.

The individual treatment of the crop in a crop carrier of the system according to the invention requires an accurate positioning of the crop carrier in relation to the different stations. With an eye hereto, a further embodiment of the system according to the invention has the feature that the transport system is adapted to guide the crop carriers in mutually adjacent transport paths, that the transport system comprises per transport path at least one at least substantially rigid transport member and that the transport member is able to engage on at least some of the crop carriers in the relevant transport path. By thus making use of a number of substantially rigid transport members, at least one per row in each case, the tolerance in the degree of displacement can be limited to a minimum. Other transport systems, such as for instance a long chain to which all crop carriers are connected, have the drawback that because of stretch and slack occurring therein the crop carriers are not positioned wholly correctly in relation to the treatment stations, whereby the efficient treatment of the crop is in jeopardy. This embodiment of the system according to the invention avoids this in that use is made of substantially rigid and therefore non-stretch transport members. The driving of the transport member must in turn preferably also take place directly and without tolerance so as to enhance accurate positioning of the crop carriers. To this end a further embodiment of the system according to the invention has the feature that at least one pressure cylinder engages on the transport member and that the transport member is able to transmit a stroke of the pressure cylinder at least almost completely as a step of a crop carrier.

Because in the above specified particular embodiment of the system according to the invention use is made of transport members which operate only per row, transport from row to row still has to be provided. With a view hereto, a further embodiment of the system according to the invention has the feature that transfer means are present at one end of a first transport path to transfer a crop carrier when it reaches this end to a second transport path, and that the transfer means are able to thus transfer a crop carrier between successive steps of the transport means. Because the transfer of a crop carrier from the one row to the following row can thus be realized within the interval between successive steps of the transport system, transport does not come to a standstill at the end of a row, and the stepwise transport of the crop carriers can continue undisturbed. In a particular embodiment the system according to the invention has the feature that the transfer means comprise lifting means for releasing a crop carrier from the first transport path, and that the lifting means are displaceable and are coupled to a pressure cylinder with a stroke which is at least equal to the intermediate distance between the first and the second transport path. Use is thus also made of a stepwise approach for transferring the crop carriers by means of the pressure cylinder, whereby a well-defined, tolerance-free step can also be given reliably for a longer period. A further, particularly practical embodiment of the system according to the invention has the more particular feature in this respect that the lifting means comprise a profile which is able to engage round an underside of a chassis of a crop carrier, and that the profile can co-act on a side remote from the crop carrier with at least one pressure cylinder to pick up the whole from the transport path.

For the crop carriers use can be made per se of any suitable form of displaceable chassis, rolling, hanging, sliding, floating or even moving in other manner. However, a particularly practical embodiment of the system has in this respect the feature that the crop carriers comprise separate rolling cultivating trolleys which run in a system of rails. By making use of a rolling system a relatively high load can be handled without problem per crop carrier, while the system of rails provides good guiding and control of the crop carriers on the one hand and can limit the friction and rolling resistance on the other. Less is therefore required of the transport means.

In the system according to the invention the growth climate of the crop can be optionally applied in wholly artificial manner, making use of the above described growth control means. Particularly for such a situation a preferred embodiment of the system according to the invention has the feature that the crop carriers are provided with multiple cultivation levels for receiving the crop in multiple layers. It will be apparent that by thus cultivating in multiple layers per crop carrier the degree of utilization and the yield of the system per unit of area can be markedly increased. The application of an artificial growth climate provides the possibility herefor in that the growth control means can be employed, optionally simultaneously, at multiple levels.

The invention will now be further elucidated with reference to an embodiment and an accompanying drawing. In the drawing: figures 1-4 show schematically a top view of an embodiment of the system at successive stages of transport of crop carriers therein; figure 5 shows a cross-section of a crop carrier and growth control station as applied in the system of figures 1-4; figure 6 is a view of a lighting and heating panel as applied in the system of figures

1-4; figure 7 is a side view of a number of crop carriers advanced by transport means in the system of figures 1-4; figure 8 is a top view of transfer means of the system of figures 1-4; and figures 9-13 show a cross-section of the transfer means of figure 8 provided with a crop carrier at successive stages of operation.

The figures are otherwise purely schematic and not drawn to scale. Some dimensions in particular are shown (highly) exaggerated for the sake of clarity. Corresponding parts are designated where possible in the figures with the same reference numeral.

Figure 1 shows a system for cultivating crops according to an embodiment of the invention. The system comprises a substantially rectangular building 10 which is at least practically wholly filled with displaceable crop carriers 20. In this embodiment the crop carriers comprise rolling carts on which the crop can be placed in four layers. The carts are about 2 metres long and have a width of about 1.25 metres, so that the total cultivation area thereof amounts to about 10 m². The system can be used to cultivate a constant flow of fresh vegetables, flower bulbs, flowers, seedlings and/or potted plants, or any other crop needing only a limited growing height as required.

Between an entrance 11 and an exit 12 of the system extends a transport route which is divided over a large number of parallel transport paths. Crop carriers 20 are placed herein in successive rows with an interspacing in the order of magnitude of 5 centimetres. The crop carriers are herein coupled per path to a transport system with which the crop carriers are moved forward in stepwise manner. In this embodiment this takes place in steps of 20 centimetres at an interval of about 36 seconds. A crop carrier with a length of 2 metres will thus move up one place in about 6 minutes and the same will apply for preceding and following crop carriers. This stepwise transport is in principle uninterrupted, so that when the system as drawn is completely filled, about every 6 minutes a crop carrier with sowing seed enters the system at an entrance 11 and a crop carrier with 10 m² product leaves the system at an exit 12. The system is dimensioned, and the transport speed adapted thereto, such that the residence time of a crop carrier in the system at least practically equals the desired growing time for the crop. The crop is hereby full-grown when it reaches the exit 12, so that it can be harvested immediately.

Used here as example is the cultivation of plants with a cultivation period of about 10 weeks. The total length of the successively rolling carts is 33,600 metres. If all of these are transported with a step of 20 centimetres every 36 seconds, it takes precisely 10 weeks before a crop carrier which has entered the system at the entrance appears at the exit. During this period the crop has the time to become full-grown. Once it has arrived at exit 12, the by then full-grown crop is harvested and dispatched, and the empty crop carrier is carried via a rapid transport system 13 to the entrance for reuse there. The crop carrier is herein cleaned carefully and optionally disinfected in a washing line 14 before being employed again.

Figures 2, 3 and 4 show successively how the crop carriers shift slowly but surely through the system. Each row herein initially has a vacant space at the end thereof. As soon as this is occupied, see figure 3, transfer means come into operation to transfer the last crop carrier in a row to the following row. This takes place synchronously on both sides in the system, wherein per side a crop carrier is transferred on every other row, see figure 4.

For crops with a cultivation period shorter than 10 weeks the system provides at the end of a number of rows a number of intermediate exits 15 where a faster growing crop can be harvested early. These intermediate exits are also used in the case of calamities and diseases to enable a row or part of a row of crop carriers to be rapidly taken outside. Because use is made according to the invention of stepwise transport, this can in principle take place without consequences for and delay of the other crop carriers in the system. If the crop is full-grown earlier than anticipated, the intermediate exits can also be used to discharge and harvest the full-grown product. An intermediate exit is provided as such, for instance from the halfway stage of the cultivation period, or halfway along the total route, for instance for every at least practically full week or other time span that the cultivation continues. During the whole residence of a crop carrier 20 in the system, the growing conditions of the crop growing thereon are monitored continuously and controlled artificially. For this purpose every crop carrier is provided with identification means which give an indication of the nature of the crop placed thereon. Growth control means are actuated by a central processing unit on the basis of this data. The growth control means are herein divided over stations 30, see figure 5, disposed along the route of the crop carriers, but which for the sake of clarity are not further shown in figures 1-4. Each station 30 herein has its own processing unit (not further shown), so that the stations function autonomously. This has the advantage that, in the case one of the stations fails, the other stations can remain in operation and the crop retains the desired growth climate for the greater part of the route.

The growth control means comprise heating and lighting means 31 in combination with sprayers 32 to regulate the air humidity and drippers 33 with which irrigation, and if desired fertilizing, can take place. The irrigation water optionally provided with fertilizers is herein collected from drippers 33 in a funnel-like gutter 21 of transport trolley 20 and distributed over the crop via a pipe network (not shown) in trolley 20.

The heating and lighting means are combined with each other in panels 31, see figure 6, which are suspended per crop layer of the crop carriers. Panels 31 herein comprise several zones 34 having therein a number of infrared radiant heaters 35 with which the ambient temperature of the crop can be controlled in a particularly directed and individual manner. The radiant heaters are relatively small ceramic elements which transmit infrared radiant heat with an exceptionally high efficiency at a relatively low power to enable the crop to be provided per crop carrier with an individual heat climate. Situated between heating zones 34 are lighting zones 36 which are assembled from a large number of light-emitting diodes (LEDs) 37,38,39. The LEDs herein consist of different types, i.e. blue, red, yellow or even white, designated in the figure with mutually differing markings. The different types of LED can be controlled separately, wherein the number of burning LEDs can be set per type. Not only can the lighting intensity of the lighting means but also a lighting spectrum can thus be adapted to the crop, thus enhancing both the yield and the crop quality. Just as the radiant heaters applied here, the LEDs are also characterized by an exceptionally high efficiency on the power consumption. Use is particularly made herein of white LEDs which are now commercially available and which are manufactured from GaAs. These LEDs supply no less than 15,000 μC of light efficiency. A matrix of 4x25 of such LEDs occupies an area of only about 4x25 cm, assuming a pitch of 1 cm, while a light efficiency of about 1.5 Candela can be obtained therewith at a power consumption of no more than about 7 watts.

Using the growth control stations 30, and more particularly the growth control means 31,32,33, the growth climate to which the crop is subjected can be regulated precisely and individually in order to generate optimum growing conditions. Account is taken here of the variety of crop and with day/night changes and other factors in the growth cycle. The position of growth station 30 in the route covered by the crop is herein translated on the basis of the transport speed into a residence time, or the age, of the crop in the system. This residence time determines for instance whether it is day or night and the lighting means are controlled accordingly. Depending on the variety of the crop, which can be accessed via the identification means on the crop carrier, the residence time also determines which air humidity, fertilizer and temperature has to be provided. The optimal growth climate is thus provided during the whole lifespan. Arranged between successive rows are climate separating means 17, see figures 1-4, in the form of plastic slat curtains extending over the whole height of the system and ensuring that mutual influencing of the growth climates on either side thereof remains limited.

Crop carriers 20 each comprise a mobile frame 22 which runs with self-lubricating nylon wheels 23 over a stainless steel system of rails 16, see figure 5. The transport system is thereby self-lubricating and the rolling resistance of the crop carriers can thus be kept permanently low. The crop carriers comprise four carrier platforms 24 at different heights with an area of about 2.5 m², so that about 10 m² of crop can be accommodated per crop carrier. Use is preferably made for this purpose of hydroponic culture, wherein harvesting takes place afterwards inclusive of the hydroponics. The hydroponics herein consist for instance of a block of mineral wool and remains adhered to the crop during harvesting and thus enhances the shelf-life and freshness of the harvested product. By thus cultivating in four or, if desired, even more layers, the surface area of the system is utilized in particularly efficient manner, and the yield per unit area is therefore significantly larger than for instance that in conventional glass horticulture. On the underside the crop carriers 20 have two pivoting hooks 25,26 which drop into a gear rack 27 integrated into the floor surface, see also figure 7. Gear rack 27 forms part of the transport system, which further comprises a hydraulic pressure cylinder 28. For stepwise advance of crop carriers 20 with steps of 20 centimetres at a time, hydraulic cylinder 28 drives a drive rod 29 in and out with a stroke of about 25 centimetres to thus allow for a certain tolerance. Because the pitch of the toothing on gear rack 27 amounts to almost exactly 20 cm, transport of crop carriers 20 nevertheless takes place in steps of exactly 20 cm. During operation the gear rack 27 is set into an oscillating movement at the above stated interval of about 36 seconds. Crop carriers 20 in the relevant row are thus pulled forward a distance of about 20 cm at a time about every 36 seconds in stepwise manner, corresponding with the pitch of the toothing on gear rack 27.

A front hook 25 of the two 25,26 drops each time into the toothing, so that the crop carrier is pulled forward thereon. By thus making use of a pulling instead of a pushing drive, bending or even buckling of gear rack 27 and other parts of the transmission is prevented, which not only prevents damage to the transport system but moreover enables a precise and well-defined positioning of the crop carriers during the whole of the transport. At the end of gear rack 27 the crop carrier is set down in free position. This is achieved in that the rear hook 26 of the two then drops into the toothing of the gear rack so that this crop carrier is now pushed forward instead of being pulled forward. Because this only affects one crop carrier in the whole row, this has no or hardly any influence on the total load on the transport system as such. As soon as the crop carrier has thus run completely off the gear rack, it can be transferred to a subsequent row with suitable transfer means. In the subsequent row the gear rack is placed the other way round, so that transport there takes place in corresponding manner, be it that now the hooks 25 push and hooks 26 pull. A small stop prevents the hooks dropping too far downward.

The transfer means which transfer a crop carrier 20 to a subsequent row when it reaches the end of each row are shown in detail in figures 8 and further. The means comprise a laterally displaceable lifting device 40 common to the different crop carriers and having two parallel lifting members 41 placed transversely of the direction of guide rails 16 for crop carriers 20. The guide rails are interrupted at this position to allow access to the lifting members. The lifting device is coupled to a hydraulic cylinder 42 with a stroke of about 140 centimetres with which a lateral displacement can be realized which is large enough to span the mutual pitch between rows in the system.

As shown in figure 9, lifting members 41 rest on a system of pot cylinders 43 which in turn support in rolling manner on a ground with a common undercarriage provided with wheels 45. The whole construction lies for at least the greater part recessed into the floor surface 19 of the system indicated schematically with a dotted line.

In order to transfer crop carriers 20 from the one row to the next, the pot cylinders 43 are energized in the starting position of figure 9 so that the crop earners are raised about 8-10 cm and are herein lifted out of rails 16, see figure 10. In this situation pressure cylinder 42 is driven outward whereby the whole unit makes a sideward stroke of about 140 cm, corresponding to the mutual pitch between the rows, so that the crop carriers are now suspended above the following row. Pot cylinders 43 are then retracted, whereby crop carriers 20 now rest once again in rails 16, see figure 12. Finally, the lateral pressure cylinder 42 is also retracted, whereby the transfer device returns again to its starting position. On both longitudinal sides of the system all of the last crop carriers in the rows are transferred synchronously to the subsequent row. This can be realized well within 36 seconds, so that crop transport in the system does not come to a halt.

The sideways transport is thus also carried out in stepwise manner, purely in the form of a translation of the crop carriers from the one row to the other. Here also this has the advantage that the positioning of the crop carrier takes place in highly controlled and defined manner. This moreover avoids the crop carriers having to negotiate bends in the rail system, which would otherwise result in additional friction and wear and readily contribute toward malfunction.

The system requires a once-only start-up cycle of 10 weeks, wherein the system is filled slowly but surely. The system then provides a fully continuous cultivation system which can be employed for diverse crop varieties. Crop carriers herein run at a speed of 20 metres/hour through the system, whereby a full crop carrier leaves the system every 6 minutes. The crop carriers have a usable cultivation area of 10 m² divided over four levels. About every 6 minutes 10 m² of crop can thus be harvested. Every time a crop carrier thus leaves the system, another one is added with sowing seed at the entrance to the system. When a crop carrier with seed enters the system, the following one is again being filled with seed. Thus results a continuous circuit of crop carriers which pass through the system in about 10 weeks, sufficiently long to allow the crop to reach full development. For crops which become full-grown more quickly, the system provides one or more intermediate exits, whereby the crop can be harvested early.

Because use is made of a completely artificial climate in the system, it can if desired be realized wholly underground. Cultivation is possible in an exceptionally efficient manner due to the invention, whereby the system, even in the case of a completely artificial growth climate, is highly competitive with conventional glass horticulture. This is shown from the following calculations.

Radish:

With continuous cultivation in conventional glass horticulture the yield of radish is on average 100 bunches of 20 radishes per m² per year. A glasshouse of 1 ha therefore produces 1,000,000 bunches of radishes per year.

A crop carrier with an area of 10 m² leaves the system every 6 minutes. This amounts to 512 bunches of 20 radishes per 6 minutes. The annual yield of conventional glass horticulture is thus achieved by the system according to the invention in about 8 days.

The cultivation area is herein provided by a chain of crop carriers about 33,600 metres in length which occupies a total area of about 47,000 m², or 4.7 ha. The invention thereby produces about 10 times more yield than conventional glass horticulture. In practice this advantage will be even greater, since the growing conditions in the system according to the invention can be individually optimized, whereby the growth cycle can optionally be shortened or a higher yield per m² obtained.

Lettuce:

Lettuce such as ordinary lettuce, crinkly lettuce and iceberg lettuce is cultivated in conventional glass horticulture for 6 periods in the year. The yield is herein variable according to the time of year, but amounts per period to an average of about 17.9 heads of lettuce per m². A glasshouse therefore produces per year per hectare 10,000 x 17.9 x 6 (periods) = 1,074,000 heads of lettuce.

In the system according to the invention each crop carrier is provided with 128 culture trays of 60x12x12 cm (lxwxh). Each tray provides space for 3 heads of lettuce. The system therefore produces 128x3=384 heads of lettuce every 6 minutes, which amounts to a production of more than 92,000 heads of lettuce per day. The annual production of conventional glass horticulture is thus achieved within twelve days.

Seedlings:

The system according to the invention is also suitable for the cultivation of seedlings.

The costs of for instance cucumber and tomato plants lie in the order of /2.- per plant.

Making use of the above stated trays, 8 plants can be cultivated per tray, which amounts to 1024 plants per crop carrier. Each plant then has available a growth substrate of 7.5x12x12 centimetres. 1024 plants can thus be harvested every 6 minutes, which amounts to a production of more than 245,760 plants per day, representing a value of

/491,520,- per day.

Because the system realizes an exceptionally large yield in a comparatively short time, it is not unlikely that more than one crop is cultivated at a time. The system does however provide the option of cultivating diverse crops simultaneously. It is thus possible to begin with 5 days of radish followed by 5 days of lettuce, 5 days of carrot, 5 days of seedlings and so divide a cycle of 70 days and have a more varied harvest. The grower can even plan precisely to the day when which particular crop can be harvested, and so optimally tailor his supply to the anticipated demand.

The system according to the invention also provides particularly great advantages from an energy viewpoint. A conventional greenhouse for glass horticulture with a crop area of 40x60 m is for instance required to cultivate 153,600 tomato plants. This generates fuel costs from the moment of sowing and these continue for the whole growing period. This is repeated for a subsequent crop. With a growing period of 10 weeks, the annual fuel costs must therefore be divided over 5 harvests. In the system according to the above stated embodiment of the invention, the system must first be filled with crop carriers. Assuming a growth period of 10 weeks, this will take 10 weeks in which no harvesting takes place. Harvesting will subsequently take place fully continuously for the rest of the year, wherein a yield of 153,600 tomtao plants can be realized per 24 hours. The annual fuel costs can therefore be divided over 42 harvesting weeks, wherein the complete harvest of a conventional greenhouse is harvested every day, or 294 harvests against 5 harvests in conventional glass horticulture. The difference is roughly a factor of 60. At

47,000 m², the area of the system as according to the above stated embodiment of the invention is roughly a factor of 20 larger than that of the above described conventional greenhouse, so that a net improvement in efficiency of a factor of 3 is achieved in respect of fuel costs. The following year the efficiency improvement will even rise above a factor of 3.5 since the initial period in which the system is filled does not then have to be completed again. No account has otherwise been taken in these calculations of efficiency improvements resulting from direct heating of the crop using radiant heaters compared to conventional integral heating of the housing, whereby the efficiency improvement can rise even further.

Although the invention has been further elucidated above solely with reference to a few embodiments, it will be apparent that the invention is by no means limited thereto. On the contrary, many other variations and embodiments are possible within the scope of the invention for the person with ordinary skill in the art. Suspended crop carriers can thus be applied instead of rolling crop carriers, wherein the transport system is modified thereto.

The described transport system, although very appropriate for the system according to the invention, is also given only by way of example and it is possible to vary this within the scope of the invention, and it is even possible to make use of a wholly different stepwise transporting transport system.

Because the described system according to the invention makes use of a fully artificial conditioned growth climate, wherein even the light is provided artificially, the system can if desired be applied wholly underground, whereby particularly in densely populated areas the expensive land above remains at least for the greater part available for other purposes, in particular house-building. This moreover provides the advantage that the crop can be produced close to the selling areas, whereby transport costs and the impact on the infrastructure are limited. The system can also be applied in those regions on earth where cultivation of crops would otherwise not be possible, or hardly so. In the given embodiment use is made of a fixed interval of 36 seconds at which the transport system advances the crop carriers. The system can however be embodied with a provision for controlling the interval so that the total residence time of the crop carriers, and thus the maximum cultivation period, can be adjusted or fine-tuned, in accordance with the variety of crop which has to be cultivated. In the given embodiment a variation of the interval by only 1 second for instance results in a change in the cultivation period of about 2 days. The invention thus provides from many viewpoints a particularly flexible cultivation system.

The invention generally provides a system for cultivating crops with which, irrespective of the environment, fully continuous production with exceptionally high efficiency is possible.

Claims

1. System for cultivating at least one crop, comprising a number of displaceable crop carriers for receiving the crop thereon and a transport system for transporting the carriers through the system during the growth of the crop, characterized in that the transport system is adapted to transport the crop carriers, at least during operation, in stepwise manner at least substantially one after another through the system.

2. System as claimed in claim 1, characterized in that the transport system transports the crop carriers through the housing in steps of Δx centimetres at an interval of Δt seconds, and that Δx and Δt are chosen such that a crop carrier has a residence time in the system which at least practically corresponds with a desired cultivation period of the crop.

3. System as claimed in claim 2, characterized in that Δx is in the order of magnitude of 20 centimetres and Δt is in the order of magnitude of 36 seconds.

4. System as claimed in claim 1 , characterized in that the system comprises an entrance and an exit for crop carriers, between which there extends a route distributed over a number of mutually adjacent transport paths.

5. System as claimed in claim 4, characterized in that the system comprises one or more intermediate exits within the route.

6. System as claimed in claim 5, characterized in that at least some of the intermediate exits are situated at an end of the transport paths.

7. System as claimed in one or more of the foregoing claims, characterized in that at least substantially every crop carrier is provided with unique identification means.

8. System as claimed in claim 7, characterized in that the identification means provide an indication of the nature of the crop in the crop carrier provided therewith.

9. System as claimed in claim 7 or 8, characterized in that growth control means are provided to influence a growth climate per crop carrier on the basis of the identification means of the crop carrier and the position of the growth control means in a transport route of the crop carrier.

10. System as claimed in claim 9, characterized in that the growth control means comprise means from a group of lighting means, heating means, fertilizing means and humidifying means.

11. System as claimed in claim 10, characterized in that the lighting means are capable of a variable spectrum adapted to the crop.

12. System as claimed in claim 11 , characterized in that the lighting means comprise a system of mutually differing light-emitting diodes which can be individually controlled, optionally in group-wise manner.

13. System as claimed in any of the claims 10-12, characterized in that the heating means comprise one or more radiant heaters.

14. System as claimed in any of the claims 9-13, characterized in that the growth control means comprise diverse stations in the system which can each be at least substantially autonomously controlled by their own central processing unit.

15. System as claimed in any of the foregoing claims, characterized in that along a transport route for the crop carriers are arranged climate separating means which are able to create a barrier between growth climates prevailing on either side thereof.

16. System as claimed in any of the foregoing claims, characterized in that the transport system is adapted to guide the crop carriers in mutually adjacent transport paths, that the transport system comprises at least one at least substantially rigid transport member per transport path and that the transport member is able to engage on at least some of the crop carriers in the relevant transport path.

17. System as claimed in claim 16, characterized in that at least one pressure cylinder engages on the transport member and that the transport member is able to transmit a stroke of the pressure cylinder at least almost completely as a step of a crop carrier.

18. System as claimed in claim 16 or 17, characterized in that transfer means are present at an end of a first transport path to transfer a crop carrier when it reaches this end to a second transport path, and that the transfer means are able to thus transfer a crop carrier between successive steps of the transport means.

19. System as claimed in claim 18, characterized in that the transfer means comprise lifting means for releasing a crop carrier from the first transport path, and that the lifting means are displaceable and are coupled to a pressure cylinder with stroke which is at least equal to the intermediate distance between the first and the second transport path.

20. System as claimed in claim 19, characterized in that the lifting means comprise a profile which is able to engage round an underside of a chassis of a crop carrier and that the profile can co-act on a side remote from the crop carrier with at least one pressure cylinder to pick up the whole from the transport path.

21. System as claimed in any of the foregoing claims, characterized in that the crop carriers comprise separate rolling cultivating trolleys which run in a system of rails.

22. System as claimed in any of the foregoing claims, characterized in that the crop carriers are provided with multiple cultivation levels for receiving the crop in multiple layers.