Device for conditioned cultivation of a crop

Abstract

A device for conditioned cultivation of a crop (5) comprises a conditioned, at least substantially daylight-free cultivation space (10) with a cultivation section (15) for receiving the crop. Artificial lighting means (30) for creating and emitting to the cultivation section photosynthetically active artificial light are present therein. The cultivation space (10) comprises in a higher zone (ZH) above a leaf system of the crop an air inlet (21) and an air outlet (22). Air treatment means are provided for creating and maintaining a primary airflow between the air inlet (21) and the air outlet (22) in the higher zone (ZH). A distributed conduit system (55) is arranged under the leaf system of the crop in a lower zone (ZL) of the cultivation space. The conduit system (55) is distributed over the cultivation section and provides between the crop plants a number of inlet openings which are coupled to the air treatment means for the purpose of introducing in the cultivation space part-flows of a secondary airflow (Ls) into the lower zone (ZL) of the cultivation space.

Description

[0001] Device for conditioned cultivation of a crop

[0002] The present invention relates to a device for conditioned cultivation of a crop, comprising a conditioned, at least substantially daylight-free cultivation space with a cultivation section for receiving the crop and with artificial lighting means which are able and configured to create and emit to the cultivation section photosynthetically active artificial light, wherein the cultivation space comprises in a higher zone thereof an air inlet and an air outlet, which higher zone lies above a leaf system of the crop, and wherein air treatment means are provided for creating and maintaining a primary airflow between the air inlet and the air outlet in the higher zone of the cultivation space.

[0003] Such a device is for instance known from European patent application EP 2.893.800 of applicant and is increasingly used as cultivation environment for indoor cultivation of crops in a closed device in which entry of daylight and other ambient factors are precluded as far as possible. As a result, a cultivation climate is imposed on the crop wholly artificially, including photosynthetically active artificial light, so that individual growth of the crop can be controlled and guided within extremely narrow limits. The cultivation and production of crops can thereby correspondingly take place in the most optimal manner possible, irrespective of the specific geographic location where the device is situated. It has been found that not only a provided light spectrum, including an artificial day / night cycle, and an ambient temperature play a significant part here, but that a considerable role is particularly also played by the moisture management experienced by the crop in the cultivation space. In existing devices of the type described in the preamble control however takes place almost only on the basis of an average relative air humidity by circulating air through the cultivation space and continuously dehumidifying (drying) or humidifying it to a desired level here. This has however been found not to be entirely optimal yet in practice.

[0004] The present invention therefore has for its object, among others, to provide a device for conditioned cultivation of crops wherein internal moisture management of the crop can be influenced and controlled on a particularly fine scale.

[0005] In order to achieve the stated object a device according to the invention has the feature that a distributed conduit system is arranged in a lower zone of the cultivation space, which lower zone does not reach above the height of the leaf system of the crop, that the conduit system provides between the crop plants a number of inlet openings distributed over the cultivation section, and that the inlet openings are coupled or are at least couplable to the air treatment means for the purpose of introducing in the cultivation space part-flows of a secondary airflow into the lower zone of the cultivation space. Fresh air is thus blown in at the height of the leaf system, or from beneath it. This air can be fully adapted to the optimal growth and development conditions of the crop. By making use here of a (large) number of inlet openings the air flow rate of the part-flows of the secondary airflow can be limited per inlet opening and the secondary airflow can thereby be distributed over the crop particularly homogeneously. Both contribute to an optimal cultivation climate of the crop.

[0006] An important factor is here the thus generated vertical air transport through the leaf system, whereby evaporation from the crop plant is discharged directly to a position above the leaf system and is received in the primary airflow without having any noticeable effect on the adjacent crop plant. The primary airflow will thereby acquire moisture content along its path from the inlet to the outlet as the airflow passes more crop plants therein. Because this primary airflow is guided in the higher zone, above the leaf system of the crop, the crop experiences no adverse effect from this increasing air humidity.

[0007] The climate management in the secondary / airflow can particularly be adjusted optimally to the needs of the crop. For this purpose a preferred embodiment of the device according to the invention has the feature that the conduit system is coupled or is at least couplable upstream to the air treatment means which are able and configured to condition the secondary airflow in order to impose one or more of a conditioned first temperature, air humidity and / or air speed thereon. The crop will thus mainly experience the first temperature, air humidity and / or air flow speed as imposed thereon by the air treatment means. It is noted here that, unless explicitly stated otherwise, in the present application the quantities air speed and airflow rate are used interchangeably without the intent of signifying any substantial difference therein. In a further preferred embodiment the device according to the invention is characterized in that the air inlet is coupled or is at least couplable upstream to the air treatment means which are able and configured to condition the primary airflow in order to impose thereon one or more of a conditioned second temperature, air humidity and / or air speed. Because the primary airflow is carried substantially wholly separated from the leaf system in the higher zone of the cultivation space, the climatological values including particularly the second air humidity, temperature and flow speed therein can be optimized with a view to the processing and conditioning by the air treatment means, which can thereby be operated considerably more economically. This latter contributes significantly to an economical efficiency of the whole installation.

[0008] The primary airflow and the secondary airflow are thus conditioned separately of each other, whereby said climate values in particular can be set independently of each other and optionally identically to each other. In a particular embodiment the device according to the invention is therefore characterized in that one or more of the air humidity, temperature and flow speed of the primary airflow differs from that of the secondary airflow. This provides an important factor and freedom of choice for setting and maintaining an optimal cultivation climate in the cultivation space. A climate in the lower zone of the cultivation space can here particularly be set and maintained differently relative to a climate in the higher zone, and thus be adapted specifically to the optimal crop conditions. Use is preferably made of an almost wholly internal air transport in the device in order to not only be able to maintain the most optimal internal climate possible, wherein no or the least possible carbon dioxide is lost, but also to prevent entry' of pathogens, weeds and other harmful ambient factors as far as possible. With this in mind a further preferred embodiment of the device according to the invention has the feature that the air outlet is coupled or is at least couplable to the conduit system and the air inlet for a recirculation of the primary airflow and the secondary airflow in the cultivation space.

[0009] A further particular embodiment of the device according to the invention has the feature that the conduit system comprises a perforated pipe system of pipe parts comprising the inlet openings in the wall thereof. An almost unlimited number of inlet openings can thus be realized, wherein a density and size of the inlet openings is chosen as desired. A particularly diffuse and delicate flow pattern can hereby be imparted to the secondary airflow.

[0010] In a particular preferred embodiment the device according to the invention is characterized in that the conduit system is coupled or is at least couplable to irrigation means which are able and configured to irrigate the crop via the inlet openings. The conduit system thus has a dual use. On one hand an air transport through the leaf system is realized thereby, for which purpose the conduit system is coupled to the air treatment means, on the other hand water, provided with nutrients, can be pumped therethrough in order to irrigate the crop. Switchable valve means, which allow the device to switch selectively between the two modes by connecting the conduit system either to the irrigation means or to the air treatment means, can be provided upstream of the conduit system.

[0011] The device according to the invention can be applied particularly advantageously with a cultivation section on which the crop is cultivated under ebb and flow. The device according to the invention is characterized here in that the irrigation means are able and configured to selectively irrigate or drain the crop via the inlet openings, in that case the conduit system is advantageously utilized to briefly submerge the crop during ebb and then pump the cultivation section empty using the same system. Following this drainage, the same conduit system is then available for the air transport of the secondary airflow. This provides a particularly efficient and economical use of production means, this contributing significantly to the economic efficiency of the device, in a specific embodiment the device according to the invention is for this purpose characterized in that the conduit system is at least substantially formed by plastic pipes with a diameter of between 60 and 100 millimetres, in which inlet openings with a diameter of a minimum of 0.5 millimetres are arranged. This has been found to be an excellent dimensioning for both the intended air transport and for the intended water management of the crop.

[0012] With a view to, among other things, such multiple use of the conduit system a further particular embodiment of the device according to the invention has the feature that the cultivation section comprises an air-permeable substrate in which or on which the crop is receivable, and that the conduit system is arranged in or under the substrate. Moisture can thus be guided with the conduit system into or onto the substrate, while the secondary airflow can flow therethrough, in this respect many liquids, and particularly water, are suitable as substrate, although a particular embodiment of the device according to the invention is in this respect characterized in that the substrate comprises a material taken from a group of grains, granulate, air-permeable polymer foam and, optionally mineral, wool.

[0013] With a view to a uniform air distribution of the secondary airflow a preferred embodiment of the device according to the invention has the feature that the crop is receivable on the substrate via a perforated yet otherwise airtight film. The perforated film provides an aerodynamic resistance in the flow path of the secondary airflow and thus creates a pressure buildup upstream. The air hereby spreads over the surface of the film and then flows out via the perforations in particularly even and homogenous manner. Particularly good results have been achieved in this respect with a particular embodiment of the device according to the invention, characterized in that a plurality of perforations, together covering a maximum of 5 percent of a surface area of the film, is arranged distributed over the film.

[0014] The invention will be further elucidated hereinbelow with reference to several exemplary embodiments and an accompanying drawing. In the drawing: Figure 1 is a first exemplary embodiment of a device according to the invention in a first operative mode; Figure 2 is a second exemplary embodiment of a device according to the invention in a second operative mode;

[0015] Figure 3 is a top view of the cultivation section of the device of figure 1;

[0016] Figure 4 is a cross-section through a first embodiment of the cultivation section of figure 3; and

[0017] Figure 5 is a cross-section through a second embodiment of the cultivation section of figure 3. it is otherwise noted here that the figures are purely schematic and not always drawn to (the same) scale. Some dimensions in particular may be exaggerated to greater or lesser extent for the sake of clarity. Corresponding parts are designated in the figures with the same reference numeral.

[0018] Figure 1 shows an embodiment of a device according to the present invention. The device comprises an at least substantially closed and daylight-free cultivation space 10 in which a cultivation climate is created and maintained within narrow limits by conditioning means provided for this purpose. These conditioning means provide a climate control installation, assumed to be sufficiently well known and therefore not shown,, for controlling inter alia an average relative air humidity (Rv) and ambient temperature in the cultivation space 10, as well as artificial lighting means in the form of a system of LED fittings 30 whereby photosynthetically active artificial light (PAR) is created and is emitted to a cultivation section 15. At the position of the cultivation section 15 a crop 5 can be received, which crop is thus exposed to the artificial light. A spectrum of the artificial light is here preferably adapted to a photo-morphological requirement of the crop 5.

[0019] The conditioning means further comprise air treatment means whereby a primary airflow is created and maintained. This primary airflow Lp is guided via an air inlet 21 provided for this purpose and consisting of one or more inlet openings into the cultivation space 10 and evacuated therefrom via an air outlet 22 of one or more outlet openings, and fed back via a first air treatment installation 20 to the air inlet 21 so that a circulation of the primary airflow Lp takes place in the cultivation space 10, as shown schematically in the figure. Both the air inlet 21 and the air outlet 22 are located in a higher zone ZH of the cultivation space which lies above a leaf system of the crop, so that the primary airflow is carried in this higher zone ZH. The air treatment by the first air treatment installation 20 gives the thus blown-in primary air Lp a specific first temperature, air speed (flow rate) and air humidity (Rv) imposed thereon.

[0020] The air treatment means additionally comprise a second air treatment installation 40. A part of the air exiting at the outlet 22 is guided via a conduit system 42 provided for this purpose, yet only drawn schematically for the sake of clarity, to the second air treatment installation 40. This second air treatment installation 40 is coupled via a switch or control valve 45 to a distributed conduit system 50 which is arranged between the crop plants 5 distributed over the cultivation section 15. This is a conduit system of plastic pipes 55, for instance of polyvinyl chloride (PVC) or polypropylene (PP), typically with a diameter in the order of 60 to 100 millimetres, such as here a diameter of 90 millimetres, a wall of which is covered at the position of the cultivation section 15 with inlet openings with a cross-section of less than a millimetre to several millimetres. Via a non-perforated feed pipe 52 the pipes 55 are fed a secondary airflow Ls by the second treatment installation 40, which imparts thereto a specific, conditioned second temperature, air speed (flow rate) and air humidity (Rv). These can be chosen optionally differing wholly or partially relative to the first temperature, air speed (flow rate) and air humidity (Rv) imparted to the primary airflow Lp.

[0021] In the operative state shown in figure 1 the control valve 45 is opened and part-flows of the secondary airflow Ls are in each case guided between the leaf system of the crop 5 and into the cultivation space 10 via the openings in the wall of the pipes 55. The secondary / airflow is thus introduced below the leaf system of the crop in a lower zone ZL of the cultivation space 10 and is preferably relatively dry / in order to enhance an optimal evaporation by the crop 5 via the leaf system. The water vapour released here by the crop is thus absorbed directly into the secondary airflow Ls at the leaf system and guided therein to the higher zone ZH and there integrates into the primary airflow Lp. Because the primary' airflow Lp flows at least substantially in the higher zone ZH above the crop, it can contain a comparatively greater proportion of water vapour without any adverse effects for the crop development, this in contrast to air flowing through the crop 5. This vapour phase represents energy which can be easily recovered when the exiting air is dehumidified by / the air treatment installations 20, 40. The latter will thereby have a considerably improved energy efficiency. Figure 2 shows a second exemplary embodiment of a cultivation device according to the invention which is here furthermore operated in a second operative state. The embodiment is largely the same as that of the first exemplary embodiment. Unless this is deviated from hereafter, corresponding components therefore have the same reference numeral as in figure 1.

[0022] In contrast to the first exemplary embodiment, the air treatment means in this second embodiment comprise only a single air treatment installation 20. Provided therein is a branch in which a part of the circulating air of the primary airflow Lp is captured and dried. The dried air is primarily treated for the secondary airflow Ls and, at the desired temperature, air humidity, guided to the valve 45 and the conduit system 50. A control valve 25 is provided here, whereby a maximum flow rate of the dried air taken off for the secondary airflow can be set. The remaining part of the dried air is mixed into the untreated air, which thereby likewise becomes proportionally drier. This air is let in as primary airflow Lp via an air inlet 21 on a first side of the cultivation space and is discharged on an opposite side via an air outlet 22.

[0023] In the operative state shown in figure 2 the control valve 45 is closed, so that the air supply to the conduit system is interrupted. Other than in the first exemplary embodiment, there is now temporarily no flow of secondary'' airflow Ls. Instead, a second control valve 65 is now opened, which is connected via a pump 60 to a water basin 70. The cultivation section 15 can hereby be submerged in water (flow) or pumped dry again (ebb) using the same conduit system, wherein the openings in the pipe system 55 in this case function as respectively irrigation openings or drainage openings, irrigation and feeding of the crop 5 can hereby be provided for relatively briefly, after which the device is once again operated in the state shown in figure 1 by switching the valve means 45, 65 accordingly. This switch-over is possible in similar manner in the first exemplary'' embodiment.

[0024] For an optimal distribution of the secondary / airflow Ls over the crop use is preferably made in the cultivation section 15 of a floor structure as shown in top view in figure 3 and in cross-section in figure 4. Use is made here in respect of the cultivation section of a base 15 of concrete, although any suitable base can be used instead. Provided therein are channels 150 which are covered with, successively, a protective film 151 of EPDM with a thickness of several tenths of a millimetre to several millimetres or another suitable plastic, and a layer 152 of fibrous textile. Received thereon are the pipes 55 of the pipe system, which are here placed in the channels 150. This pipe system comprises a main conduit 52 which can serve as feed and discharge, and a number of perforated branches 55 in which the openings are provided. The branches 55 lie between and under the crop 5 and are here placed counter to each other, wherein a first branch 55 from the one main conduit 52 is followed by a final branch 55 from the other main conduit 52, and so on. This results in the arrangement shown in the figure, wherein a substantially uniform pressure distribution of a fluid, i.e. air or liquid, carried through the conduit system will be experienced in the branches 55. The whole is covered with a relatively thick air-permeable layer 153 of, in this case, a mineral granulate or grains. A ventilating geotextile 154 is arranged thereon in order to fix the layer 153, successively followed by a perforated film 155 and a mulch fleece 156, which has been omitted in figure 3 for the sake of clarity. The crop 5 can be received on the mulch fleece 156 in pots or in other manner.

[0025] The perforated film 155 is formed from a suitable plastic such as PVD or EPDM or other material which, with the exception of the perforations provided therein, is airtight. The perforations have a cross-section of a fraction of a millimetre to several millimetres and cover a total of no more than 5 percent of the available surface area of the film 155. The film 156 provides thereby a significant air resistance, which results in a pressure buildup in the secondary airflow Ls upstream of the film. During irrigation of cultivation section 15 the film with the perforations is sufficiently open. The pressure buildup provides for a certain bulging of the film 155 and the fleece 156, 'wherein results a lateral pressure equalization which results in the manner of a plenum in a particularly homogenous air distribution in the secondary airflow. This contributes all the more to a uniform crop development.

[0026] Figure 5 shows an alternative layer structure of a cultivation floor in the cultivation section. Use is here also made of a base 15 of concrete. Provided thereon or partially therein is a number of perforated ducts 75 or other porous conduits whereby an irrigation optionally provided 'with nutrients and / or other plant-enhancing means can be alternately supplied and drained in a so-called ebb / flow system. The base has a gradient in the order of 2 to 3 percent toward these ducts 75, so that water can flow easily back thereto. To the side of the ducts 75 a conduit system of perforated conduits 55 is arranged distributed over the cultivation section 15. These conduits are the same as or similar to the conduits of the preceding exemplary embodiment, but serve here only to supply a secondary vertical airflow. For this purpose the conduit system 55 is connected, as it is in the preceding exemplary embodiment, to air treatment means whereby a secondary airflow Ls can be guided through the leaf system of the crop in vertical direction, as 'was elucidated in the preceding example. In an alternative embodiment the conduits 55 can otherwise also be utilized for irrigation and drainage if desired, parallel to the ducts 75. In the same or a further embodiment variant air can if desired also be introduced into the bottom via the ducts 75 by connecting the air treatment thereto, parallel to the conduits 55.

[0027] Both the perforated conduits 55 and the ducts 75 lie embedded in an air-permeable layer 163 of granules, gravel or other type of porous substrate material. Arranged thereon is a mulch fleece 164 which fixes the underlying layer 163. In order to enhance an air distribution of air supplied via the pipe system 55 a perforated film 165 identical or at least similar to the film 155 of figure 4 is arranged over the whole, wherein the air- permeable film 165 is covered for protection with a suitable geotextile 166 on which the crop 5 can be received.

[0028] Although the invention has been further elucidated above on the basis of only several exemplary embodiments, it will be apparent that the invention is by no means limited thereto. On the contrary, many variations and embodiments are still possible within the scope of the invention for a person 'with ordinary skill in the art.

Claims

Claims:

1. Device for conditioned cultivation of a crop, comprising a conditioned, at least substantially daylight-free cultivation space with a cultivation section for receiving the crop and with artificial lighting means which are able and configured to create and emit to the cultivation section photosynthetically active artificial light, wherein the cultivation space comprises in a higher zone thereof an air inlet and an air outlet, which higher zone lies above a leaf system of the crop, and wherein air treatment means are provided for creating and maintaining a primary airflow between the air inlet and the air outlet in the higher zone of the cultivation space, characterized in that a distributed conduit system is arranged in a lower zone of the cultivation space, which lower zone does not reach above the height of the leaf system of the crop, that the conduit system provides between the crop plants a number of inlet openings distributed over the cultivation section, and that the inlet openings are coupled or are at least couplable to the air treatment means for the purpose of introducing in the cultivation space partflows of a secondary airflow into the lower zone of the cultivation space.

2. Device according to claim 1, characterized in that the conduit system is coupled or is at least couplable upstream to the air treatment means which are able and configured to condition the secondary airflow in order to impose one or more of a conditioned first temperature, air humidity and / or air speed thereon.

3. Device according to claim 1 or 2, characterized in that the air inlet is coupled or is at least couplable upstream to the air treatment means which are able and configured to condition the primary airflow in order to impose thereon one or more of a conditioned second temperature, air humidity and / or air speed.

4. Device according to one or more of the preceding claims, characterized in that one or more of the air humidity, temperature and flow speed of the primary airflow differs from that of the secondary airflow.

5. Device according to one or more of the preceding claims, characterized in that the air outlet is coupled or is at least couplable to the conduit system and the air inlet for a recirculation of the primary / airflow and the secondary / airflow in the cultivation space.

6. Device according to one or more of the preceding claims, characterized in that the conduit system comprises a perforated pipe system of pipe parts comprising the inlet openings in the 'wall thereof.

7. Device according to one or more of the preceding claims, characterized in that the conduit system is coupled or is at least couplable to irrigation means which are able and configured to irrigate the crop via the inlet openings.

8. Device according to claim 7, characterized in that the conduit system is coupled to valve means which selectively connect the air treatment means or the irrigation means to the conduit system.

9. Device according to claim 7 or 8, characterized in that the irrigation means are able and configured to selectively irrigate or drain the crop via the inlet openings.

10. Device according to one or more of the preceding claims, characterized in that the conduit system is at least substantially formed by plastic pipes with a diameter of between 60 and 100 millimetres, in which inlet openings with a diameter of a minimum of 0.5 millimetres are arranged.11 . Device according to one or more of the preceding claims, characterized in that the cultivation section comprises an air-permeable substrate in which or on 'which the crop is receivable, and that the conduit system is arranged in or under the substrate.

12. Device according to claim 1 1, characterized in that the substrate comprises a material taken from a group of grains, granulate, air-permeable polymer foam and, optionally mineral, wool.

13. Device according to claim 1 1 or 12, characterized in that the crop is receivable on the substrate via a perforated yet otherwise airtight film.

14. Device according to claim 13, characterized in that a plurality of perforations, together covering a maximum of 5 percent of a surface area of the film, is arranged distributed over the film.

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