Patent Publication Number: US-10757876-B2

Title: Cultivation system for cultivation on water in a basin and floating carriers therefor

Description:
This application is a continuation application of co-pending U.S. patent application Ser. No. 14/902,429 entitled “Cultivation System for Cultivation on Water in a Basin and Floating Carriers” filed Dec. 31, 2015, which is a 371 national stage application of PCT Patent Application No. PCT/NL2014/050328 entitled “Cultivation System for Cultivation on Water in a Basin and Floating Carriers Therefor” filed on May 22, 2014, which claims priority to Dutch Patent Application No. 2011089 filed on Jul. 4, 2013, the entire contents of which are incorporated herein by reference. 
    
    
     The present invention relates to a carrier for use in a cultivation system for cultivating crops on water in a basin. 
     It is generally known to make use here of floating carriers in the basin which have a rectangular form and have growth locations therein which form passages for providing roots of the crops with access to water in the basin. Such floating carriers are for instance known from WO-2010/093248, and such floating carriers more particularly take a form generally similar to a tray, i.e. approximately square and only a little rectangular, and in any event not elongate. Side walls extending downward during use enclose an air layer in order to impart buoyancy to these known tray-like floating carriers. The known tray-like floating carriers are for instance moulded or pressed from a thin layer of plastic and are soft and pliable, which may perhaps suffice for the buoyancy of the floating carriers. It is the object here to provide simple and inexpensive floating carriers with the desired buoyancy and the ability to (manually) handle such floating carriers to a desired extent, and it is precisely here that there is a problem. 
     The objective, particularly in the case of crops such as lettuce, is bulk production and, in combination therewith, a far-reaching degree of automation. Scaling up the size of the known floating carriers does not provide a solution here. 
     The present invention therefore has for its object to provide embodiments of carriers for cultivating determined crops on water in a basin or a pond which is suitable for far-reaching automation and bulk production. Provided for this purpose according to the present invention is a carrier with the features defined in the appended independent claim. 
     According to the present invention an embodiment which is automated to far-reaching extent is made possible for the purpose of cultivating determined crops, such as lettuce, on water in a basin or pond. The floating carriers are sufficiently sturdy and strong for this purpose even when very long floating carriers are applied, which allows mechanical processing such as lifting out of the basin, using a lift, floating carriers having therein at least approximately fully-grown crops and the associated weight in addition to the weight of the floating carriers themselves. Such strengthened floating carriers are also suitable for engagement by even a pivot mechanism. The specific configuration of the cultivation system with, among other parts, the pivot mechanism particularly provides for minimization of the space required for the cultivation system. 
     The broadest framework for the scope of protection for the present invention is outlined with reference to the appended independent claim. Many preferred embodiments are possible within this framework and these are defined in the dependent claims, to which reference is made here. 
     It is important here in this respect to point to the features of the floating carriers which enable mechanical processing other than and/or in addition to transport or displacement. 
     Particular reference is made here to processes oriented toward growth locations, such as the planting of young crops, the cultivation of at least approximately fully-grown crops and so on. A cultivation system with floating carriers, and each of the floating carriers per se, is designed for this purpose such that mutual distances between growth locations are precisely predefined, also at transitions between successive floating carriers. 
    
    
     
       Following the foregoing general specifications of the present invention, inter alia with reference to the appended claims, there follows hereinbelow the more detailed description of specific embodiments, which are shown only by way of illustration and will be described below without limitative effect on the scope of protection according to the claims. In the drawing: 
         FIG. 1 ,  FIG. 2  and  FIG. 3  show respectively a top view, a perspective view of a detail and a perspective view of another detail of a cultivation system according to the present invention; 
         FIG. 4 ,  FIG. 5  and  FIG. 7  shows respectively a perspective view of a cross-section through, a front view and a top view of a floating carrier in a first embodiment according to the present invention; 
         FIG. 6  shows a plant pot for use together with floating carriers according to the present invention; and 
         FIG. 8  and  FIG. 9  show respectively a front view and a top view of a second embodiment of a floating carrier according to the present invention; 
         FIG. 10  depicts a crop holder placed in an outer pot. 
         FIG. 11  shows a sectional view of a basin according to the present invention having additional features relating to a bridge over the basin; 
         FIG. 12  shows yet another embodiment of a floating carrier according to the invention; 
         FIG. 13  shows a second mode of use of the embodiment of the floating carrier according to  FIG. 12 ; and 
         FIG. 14  shows an embodiment of ponds or basins, which are connected or connectable for transfer of water or fluid in general from the one to the other (and/or vice versa). 
     
    
    
       FIG. 1  shows a cultivation system  1  for crops for bringing the crops, such as lettuce, to full growth in floating carriers on water. Cultivation system  1  comprises a basin  2  with water therein. Basin  2  comprises two elongate production ponds  3 . Shown on the right-hand side in  FIG. 1  is an infeed end  4  on a short side of the elongate production ponds  3  and the basin  2  assembled therefrom. An outfeed end  5  is located opposite infeed end  4 . 
     Floating in each of the production ponds  3  are large numbers of elongate floating carriers  6 , only several of which are shown in  FIG. 1 . The length of floating carriers  6  corresponds to the width of the elongate production ponds  3  and floating carriers  6  float or are moved forward in an orientation transversely of a longitudinal direction of the elongate production ponds  3 . Floating carriers  6  are displaced through an associated one of the two production ponds  3  from infeed end  4  to outfeed end  5  at a rate corresponding to development of the plants to full growth. The length of production ponds  3  is for instance adapted to this purpose. 
     As shown for instance with reference to a schematically represented floating carrier  6  in  FIG. 3 , floating carriers  6  each comprise a number of growth locations  7  for the crops. In growth locations  7  holders  13  for the crops or roots of the crops extend into the water as shown in  FIG. 5 , wherein holders  13  are shown in more detail in  FIG. 6 , wherein shoulders  14  of holders  13  can rest on teeth  15  of a fork for manipulation of holders  13  and the crops therein. 
     Cultivation system  1  in  FIG. 1  further comprises a transport system. This transport system comprises a lifting mechanism  16  (see  FIG. 3 ) at outfeed end  5  and a lowering mechanism designated schematically with arrows in  FIG. 1  at infeed end  4 . Such a lowering mechanism can have an embodiment similar to that of lift  16  at outfeed end  5  as shown in  FIG. 3 . 
     The transport system further comprises a conveyor  8  along infeed end  4  between the lowering mechanism and a long side  9  of the elongate production ponds  3 . A conveyor  11  is also arranged along outfeed end  5  between the lifting mechanism and the long side  9  of the elongate production ponds  3 . At least one conveyor  10  is further arranged along the long side  9  of the elongate production ponds  3 . 
     The transport system of the cultivation system further comprises according to the present invention two pivot mechanisms  12 . A first pivot mechanism is arranged between conveyor  8  along infeed end  4  and the at least one conveyor  10  along the long side  9  of the elongate production ponds  3 . A second pivot mechanism  12  is arranged between conveyor  11  along outfeed end  5  and the at least one conveyor  10  along the long side  9  of the elongate production ponds  3 . The amount of space required for cultivation system  1  can be limited by arranging these pivot mechanisms  12 . This further makes it possible for floating carriers  6 , which have been taken out of the water in basin  2  at the outfeed end  5 , to be displaced back to infeed end  4  along the shortest possible path via the at least one conveyor  10 . It is noted here that with the arrangement of pivot mechanisms  12  as shown in  FIG. 1  each of the floating carriers  6  is placed with the lowering mechanism into the water of basin  2  at the infeed end in the same orientation as the orientation of floating carriers  6  when they are lifted out of the water with lift  16  at outfeed end  5 . Particularly in respect of throughput of the floating carriers in a constant orientation as described below with reference to  FIGS. 7-9 , such a constant orientation of the floating carriers during throughput and optional processing or handling outside basin  2  can be highly favourable and relevant. 
     In an alternative embodiment (not shown) it is possible for pivot mechanisms  12  to be configured and designed to pivot over basin  2 . 
     In the embodiment shown here basin  2  comprises two production ponds  3 , although more production ponds are likewise possible. Production ponds  3  lie parallel to each other. Indicated schematically at the top of  FIG. 1  is that more than two production ponds  3  can be provided. The orientation of production ponds  3  remains determinant here in defining orientations in a cultivation system according to the present invention. In fact the basin  2  is divided into two or more ponds  3 , possibly only by an imaginary division line  77 . For a high efficiency of use, floating carriers in each pond  3  are aligned in parallel and at a short intermediate distance between longitudinal ends thereof at a division line  77 . Alternatively for a division line, the basin  2  may comprise more than one pond  3  separated by a barrier, separation or division  120  along line  77  between ponds  3  in basin  2 , as indicated in  FIG. 11 . As a further alternative, a basin  2  may comprise a single pond  3 . However, having multiple ponds per basin may contribute to higher capacity (more floating carriers, wider basins  2  comprising multiple ponds  3  for limiting the length of the floating carriers in each pond), more diversity in crops grown in each of the ponds and requiring distinct growth periods, enhanced enclosure of added air or oxygen underneath floating carriers  6  since more surface area of the water body in basin  2  can be covered by more floating carriers, and the like. Also, facilities alongside the basin can be shared between ponds  3  of the basin  2 , such as in the case of the below described lift  16 , which could be movable along the outfeed end  5 . 
     In the embodiment of  FIGS. 1 and 11 , a bridge  78  is shown to span over the width of the basin  2 . The bridge  78  is displaceable in this embodiment along the length of the basin  2  or ponds  3  and can roll over wheels  79  in the direction of the double arrow arranged at the bridge  78  in  FIG. 1 . As a consequence, specific processing steps can be performed automatically, such as spraying plants and crops, sucking away lice, and illuminating the plants regularly with ultraviolet light to kill fungi. The bridge  78  may alternatively be stationary or be movable over tracks or the like. 
     The bridge  78  may comprise a spanning structure  81  to extend over the basin  2 . 
     On spanning structure  81  of bridge  78 , a tank  80  may be provided to contain any one or more than one of water, nutrients, detergents, pesticides, herbicides and/or other content. Such contents may be supplied from a side of basin  2 , instead of storage in tank  80  on spanning structure  81 . Such content can be sprayed, using a pump  82  and spray lines  83 , from above onto plants or crops, like lettuce, in or on floating carriers  6  in ponds  3  of basin  2 . Spray lines  83  may be arranged to extend to both sides of the spanning structure  81 , whereas spray line  83  in  FIG. 1  is only shown to extend from the middle to the right side of the spanning structure  81 . In this manner crops can be watered or be supplied with nutrients, detergents, pesticides, herbicides and/or other content. In particular watering can be beneficial during early stages of the crops development, in which early development stages, roots of the crops will not (yet) have reached the surface of the water body in basin  3 . In particular in embodiments of floating carriers covered with cloth and in particular jute, the feature of spraying the floating carriers may contribute to preventing the roots of younger crops or plants from drying out, simply by wetting the cloth and in particular the jute. 
     Spanning structure  81  may further, at an underside thereof, comprise UV light sources  84 . UV light sources can be employed to kill fungi or mildew, and the context with the basin has not been disclosed previously. These UV light sources can be powered using a battery, for example on the spanning structure  81 , or a mains connection. A manner of connecting UV light sources  84  to a mains connection at a side of basin  2 , or in any case distant from the bridge  78 , is well within reach of any skilled person to resolve. UV light sources  84  can be arranged on a separate bridge (not shown) from the one carrying the spray lines  83  or even the stationary boom (not shown) extending across the basin  2 . 
     Likewise, a suction system  86  can be provided on spanning structure  81 , or on an additional bridge (not shown) or suspended from a stationary boom (not shown). However, it is preferred that spraying and/or UV light for killing fungi and/or suction for removing lice can be displaced along the length of the basin  2 , so that such processing can be performed on plants or crops, growing on floating carriers  6  in every stage of development of such plants or crops. 
     The suction system  86  comprises a holding container  85 , which is connected to a suction pump  87 , which in turn is connected to a suction head  88 , which can be lowered to and raised from the floating carriers  6 . With the suction head  88  in a lowered position, and the suction pump  87  in operation, lice and dust can be sucked off the plants or crops on the floating carriers  6 , and into the holding container  85 . Also, for instance lettuce leaves are surprisingly reported to become tougher when regularly subjected to vacuum cleaning and/or rustling the leaves in some other manner. With the suction heads  88  in the raised position, the way is clear for spray lines  83  or UV light sources  84  to be put to good use. 
     Separate bridges for a distinct functionalities can provide an advantage that operation of the elements and components for specific functionalities can be operated at random, without having to ensure that for instance UV light sources are inoperative, when spray lines are activated, and the like. On the other hand, suction system  86  is not likely to be very effective during operation of the spray lines or shortly thereafter. Consequently, a minimum of one bridge  78  is likely to suffice, and more bridges can be beneficial, although this would result in an increase in costs of the system in its entirety. 
     Further, it is noted here entirely separate and independent from bridge  78  and from the features thereof, that the at least one floating carrier  6  can comprise stands or feet  90 . In the embodiment of  FIG. 11 , it is shown that the basin comprises an filling or evacuation system  89  to selectively lower or raise a water level in each of the separated ponds  3  of the basin  2 . The evacuation system  89  comprises a pump  91  and is connected to the water body in the basin  2 . Pomp  91  can be reversed for filling or replenishing the basin  2 . When evacuation system  89  has been operated to lower the water level in the basin  2 , such as of the right hand pond  3  of the basin  2  in  FIG. 11 , the objective thereof is to temporarily remove water from the roots, to prevent rot or other harmful effects resulting from prolonged submersion in the water of basin  2 , and/or aeriation of the roots to promote the development of plants in or on the floating carriers. In a situation of lowered water levels, injury of root systems of plants or crops growing on floating carriers  6  can be prevented in that floating carriers  6  have supports, stands or feet  90  to support floating carriers  6  on the floor  92  of basin  2 . Additionally to or alternatively for the feet  90 , floating carriers  6  may rest on conduits  45 ,  75  of the water and/or air and/or oxygen supply system described above, in a lowered water level situation. Consequently, an effective ebb and flood system can be realized in conjunction with floating transport of the floating carriers  6  through the pond(s)  3  of basin  2 . Water from basin  2  can be transferred, to achieve a system wherein water may be sequentially evacuated from the ponds or basins. Evacuation system  89  having pump  91  can be embodied such that water from one of the ponds  3  can be pumped away to and arbitrary holding tank, or natural or artificial lake, and/or the like, to achieve essentially the same effect. for independent level control of the ponds  3 , this can only function properly if a barrier, separation or division  120  is provided between the ponds  3  along line  77  as indicated above in relation to  FIG. 1  and shown in  FIG. 11 . 
     If the ponds  3  are separated, i.e. remote from each other over a considerable distance, and are contained essentially each in an own basin  2 , each pond  3  or basin  2  can have its own water purification installation  30 , which will be described below. In such an embodiment, as shown in  FIG. 14 , connection pipes  108  can be arranged between the distinct ponds  3  and/or more preferably between reservoirs  34  belonging to the ponds  3 . Using pumps  109 ,  110 , water can be transferred from one pond  3  to the other pond  3 . Non-return valves  111 ,  112  ensure that a desired flow direction is achieve, together with schematically represented valves  113 ,  114 ,  115 , and  116 . When the ponds are separated, pumps  109 ,  110  are idle and valves  114  and  115  are closed, as shown in  FIG. 14 . When water is to be transferred from the left pond  3  to the right pond  3 , pump  109  is activated and only valve  114  is open. Valve  113  is closed to prevent circulation of the water from pump  109  back to the originating left pond  3 . Additionally or as an alternative for open valve  114 , valve  115  can be opened for transfer of water from the left to the right pond in  FIG. 14 , such that water transferred is inserted into the right pond  3  via the conduits  45 . If water is to be transferred in the opposite direction, pump  110  is activated and only valves  113  and  115  are kept open for the transfer to be effected from the right to the left pond via the conduits  45  of the left pond  3 . 
     Additionally or alternatively, a submerging station may be provided along the length of basin  2 , where floating carriers  6 ,  93  may be submerged into the water in basin  2  to wash the crops growing and/or developing in or on the floating carriers  6 ,  93 . The submerging station may be mobile, like the bridge  78  of  FIG. 11  and may even be a part of the bridge  78 , with for instance extendable pushers (not shown) extending downward from the spanning structure of the bridge  78 . 
     In an embodiment with two or more production ponds  3  a cultivation system can have the feature that at least one of the lifting mechanism at outfeed end  5  and the lowering mechanism at infeed end  4  is displaceable along respectively outfeed end  5  and infeed end  4  of basin  2  in order to place floating carriers  6  in or remove them from basin  2  at a desired location in a relevant one of the two production ponds  3 . 
     Diverse handling or processing stations are disposed along conveyor  10  along the long side  9  of basin  2 , i.e. a cleaning station  17 , a harvesting station  18  and a planting station  19 . 
     Cleaning station  17  is represented symbolically by spray nozzles  20 . With the object of achieving proper cleaning the floating carriers  6  for cleaning are preferably manufactured from a smooth plastic. 
     At harvesting station  18  containers or trays  23  are supplied in the direction of arrow  21 , filled with harvested crops, and filled trays  23  are subsequently discharged in the direction of arrow  22 . 
     At planting station  19  containers  24  filled with seeds or young plants are supplied in the direction of arrow  25 , after which the seeds/young plants/crops are transferred to growth locations  7  in floating carriers  6 , as for instance shown schematically in  FIG. 5 , with floating carrier  6  in a floating state in  FIG. 5 . Emptied containers  24  are then discharged in the direction of arrow  26 . 
     In a potential embodiment, in particular of interest in case of supply of seeds, floating carriers  6  can be placed temporarily in a growth cell (not shown, but roughly positioned at location  100  in the schematic representation of  FIG. 1 ) for example for germination of the seeds. To this end, floating carriers  6  may need to be taken out of the circulatory system shown in  FIG. 1 . To this end a robot type of transporter (not shown) may be employed to grab a floating carrier  6  before or after seeds are planted thereon or therein, after which the floating carriers  6  can be placed in the growth cell. Once the seeds have germinated and some roots have developed, the floating carriers  6  may be taken from the growth cell and be inserted back into the circulatory system at transporter  8  or  10  to be entered into the basin  2 , in the same manner as when young plants/crops are supplied and put into the plant positions of the floating carriers  6 . 
     A floating carrier  6  moving over conveyor  10  in the direction of arrow A is lifted out of the water of basin  2  using lift  16 , transported by conveyor  11  and pivot mechanism  12  to conveyor  10 , along which harvesting takes place at harvesting station  18 , floating carriers  6  are cleaned at cleaning station  17  and new young plants are placed in floating carriers  6  in the manner shown in  FIG. 5 , in particular into holders  13 , and transported via the additional pivoting station to infeed end  4  using a lowering mechanism to lower the floating carriers into the water of basin  2 . 
     Cultivation system  1  comprises an advancing mechanism for displacing floating carriers  6  through production ponds  3 . The advancing mechanism comprises a tractive device embodied as elastic cable  27 , the cable  27  extending from outfeed end  5  to a cross beam  28  in production pond  3 . Cable  27  exerts a force in the direction of arrow B on cross beam  28  so that floating carriers  6  floating in the direction of arrow B in front of cross beam  20  are pulled to outfeed end  5 . The advancing mechanism further comprises a retractive device located opposite cable  27  relative to cross beam  28  and here in the embodiment of a selectively actuable winch  29  connected to cross beam  28 . Using winch  29  in an actuated state thereof the cross beam  28  can be pulled back to infeed end  4  in order to create space between a series of floating carriers  6  floating in production pond  3  and the cross beam  28  pressing on these floating carriers  6 , so that a lowering mechanism, not shown in more detail, is able (arrows C) to place a new floating carrier  6 , just filled with young plants, between the already floating floating carrier  6  and cross beam  28 . 
     From infeed end  4  the floating carriers  6  are moved forward with this advancing mechanism to outfeed end  5  at a rate corresponding to development of the crops to full growth. 
     The cultivation system further comprises a water purification installation  30  as shown in more detail in  FIG. 2 . Water purification installation  30  also fulfils a function for supplementing water in the basin when this is deemed necessary in order to form a water supply installation. Provided for this purpose is a water tank  31  which can add water to a reservoir  34  via a float configuration  32  and a discharge  33  when the level in reservoir  34  falls below a level to be determined with float configuration  32 . Reservoir  34  is in open connection with basin  2  via a channel  35  so that replenishment of water from tank  31  into reservoir  34  is caused immediately in the case of a low level of water in basin  2 . Water purification installation  30  can also comprise a container  36  for nutrients, pesticides, herbicides and the like. A conduit  41  runs from container  36  to a discharge  40  at reservoir  34  via a pump  37 , for instance a selectively controllable electric pump which is selectively connectable to a voltage source  39  using a control  38 . Fresh water from tank  31 , substances from container  36  and a quantity of water from basin  2  are thus mixed in reservoir  34 . This mixture is suctioned out of the reservoir via a pump  42  and fed to a cleaning system  43 , for instance a cleaning system based on ultraviolet light. A conduit  44  runs from cleaning system  43  through reservoir  34  and channel  35  between basin  2  and the reservoir  34  to a circulation conduit  45 . Circulation conduit  45  comprises outflow openings  46  at mutual distances in order to realize a uniform distribution over basin  2  of fresh water added from tank  31 , substances from container  36  and cleaned recycled water from basin  2 . 
     Circulation conduit  45  is arranged in and at least partially around basin  2 , wherein it is noted that the circulation conduit can alternatively comprise a random number of linearly extending pipes extending in the longitudinal direction of production ponds  3 , such as the conduits  75  in the embodiment of  FIG. 2 , which also comprise outflow openings  46  therein for as uniform distribution as possible of fresh or recycled water and/or substances. 
     Further, the cultivation system may comprise an air supply installation  76 , comprising an air pump  74 , connected in the shown embodiment to conduit  44  on the one hand and extracting air from its surroundings on the other hand. More preferably, air pump  74  is connected to an oxygen supply. Thereby air or oxygen may be injected into the water body in basin  2  underneath the floating carriers  6 . Since the elongate floating carriers  6  are arranged or oriented in a side-by-side configuration, as they are moved through basin  2 , the floating carriers  6  effectively cover much if not most if not all of a surface area of the water body in basin  2 . Air injected into the water body in basin  2  through openings  46  in conduits  45  or  75  will tend to rise to this surface area of the water body. Most of this air or oxygen will be captured underneath the floating carriers  6 , in stead of dissipating into the air above the ponds  3 . The air or oxygen, that is trapped underneath the floating carriers  6  in this manner will beneficially influence root growth of plants developing in the floating carriers  6 . For the supply of air or oxygen, the same conduits  45 ,  75  may be used as for supply of fresh or recycled water and/or substances, but additionally or alternatively, separate conduits may be employed for liquids and for gasses, in particular for water and/or substances on the one hand and for air and/or oxygen on the other hand. For instance, the conduits  75  may be exclusively connected to the air supply installation  76 , which may supply air in general or mainly oxygen, and circulation conduit  45  may be dedicated to supply of fresh and/or recycled water and/or substances. 
     Lifting mechanism  16 , which is schematically represented in  FIG. 1  and shown in more detail in  FIG. 3 , comprises a float  47  displaceable up and downward in the water in basin  2  along at least one guide  48 . In a situation where it floats on the water the float  47  forms a stop for floating carriers  6  in production ponds  3 . Particularly when elastic cable  27  exerts a pulling force in the direction of arrow B on floating carriers  6  lying side by side, space must be created to take a floating carrier  6  lying closest to outfeed end  5  out of the water using lift  16 . Provided for this purpose is a crane  49  which is movable up and downward in the direction of double arrow D and which is represented schematically with a hook thereof. Frame  50  with teeth or carriers  51  thereon is suspended from hook  49 . When hook  49  of the crane is lowered, the weight of the crane and the frame  50  resting on the float will press on float  47  and press float  47  downward, wherein float  47  can move in downward direction over guides  48  in the form of simple rods  48 . When the float forming a stop for floating carriers  6  is pressed away downward and the teeth or carriers  51  have been immersed to a desired depth in the water while elastic cable  27  pushes floating carriers  6  toward outfeed end  5 , a floating carrier  6  lying closest to outfeed end  5  will be positioned directly above the teeth or carriers  51  of frame  50 , and immediately thereafter the hook  49  of the crane can be pulled upward in the upward component of the direction indicated with double arrow D. Depending on the dimensioning of the carriers or teeth  51 , a single floating carrier  6  at a time can be lifted out of the water or more than one of the floating carriers  6  can be lifted simultaneously out of the water. 
     Thus implemented is the feature enabling an underside of at least one of the floating carriers  6  to be engaged by crane  49  at outfeed end  5  for the purpose of lifting the carrier out of the water of basin  2 . 
       FIG. 4  shows a possible embodiment of one of the floating carriers  6 . Floating carrier  6  comprises two continuous beams  52  which are hollow but could alternatively be manufactured from material which is solid or in any case buoyant. Beams  52  extend as strengthening beams over substantially the whole length of the elongate floating carrier  6 . A sufficiently stiff, robust and strong construction of floating carriers  6  can thus be provided, also in combination with connecting plates  53  which extend between beams  52 . On the basis of the thus realized stiffness and strength of floating carriers  6  equipped with beams  52  intensive manipulation of floating carriers  6  is possible even with very simple lifting systems, such as lift  16  in  FIG. 3 . It is precisely as a result of the profiles of beams  52  being closed all the way round the cross-section that the desired degree of stiffness and strength is achieved. 
     Backing elements  54  are arranged between beams  52  in addition to connecting plates  53 . Backing elements  54  comprise openings  55  for receiving holders  13  as shown in  FIG. 5 . Holders  13  can be easily manipulated or transported per se using teeth  15  of a fork which can engage on holders  13  under a shoulder  14  as shown in  FIG. 6 . In a specific embodiment the holders can comprise a second shoulder  56  with a larger diameter d, wherein this second shoulder  56  can come to rest on the periphery of openings  55  of floating carriers  6 . It will be evident that connecting plates  53  also comprise passages  57  for passage of either a bottom  58  of holders  13  or roots  59  of the crop being cultivated in holders  13 . In preference (only) the bottom of holders  13  is immersed in the water. In combination with passages  57  openings  55  define the growth locations  7  of floating carriers  6 . 
     During harvesting of the crops holders  13  can be placed in outer pots  70  as shown in  FIG. 10 . The outer pot comprises water up to a level  71  and holders  13  with the (almost) fully-grown crops therein can be snapped with a flanged edge  73  into a protrusion  72  of outer pot  70 . Transport to a destination, such as a shop or wholesaler or auction, is therefore easily realized without the risk of the crops becoming short of water. The water supply up to level  71  will be maintained for the crops even if outer pots  70  in assembled state with holders  13  are shaken or come to lie on their side, since the water in outer pot  70  is enclosed by means of the snap connection. Flow of water out of the outer pot will in any case be obstructed as a result. 
     Floating carriers  6  can be extrusion profiles. The end surfaces thereof can be closed with covers or inserts, or plates can alternatively be welded or fused to the outer ends of beams  52  in order to realize a good watertight seal of beams  52 . 
     Also, in a further embodiment, as shown in  FIGS. 12 and 14 , a limited number of beams  119  or tubes may carry a frame  117  in which a honeycomb type plate  107  can be deposited, where the honeycomb plate defines channels for guiding root growth to a lower lying water level. On the honeycomb plate  107 , a cloth or jute element  98  may be draped or deposited. Alternatively, as shown in  FIG. 13 , the frame  117  may accommodate on flanges  118  thereof (or in any other suitable manner) the previously described floating carriers  6  of  FIG. 4 , instead of the honeycomb plate  107 . In the representation of  FIG. 13 , two floating carriers  6  are shown to be accommodated in frame  117 , but the frame  117  is dimensioned to contain three such floating carriers  6 . The honeycomb plate may be associated with baby leaf production, whereas the floating carriers in any of the disclosed embodiments may be associated with production of crops of lettuce. 
     The versatile frame  117 , in which a honeycomb plate  107  or at least one floating carrier  4  may be accommodated, allows for the same or at least a similar manner of processing, regardless of the type of produce (babyleaf or crops of lettuce), for which appropriate inserts (honeycomb plate or floating carriers) can be employed, whilst lifts and the like can remain uniform without regard for the type of produce, as these would act on the frame  117  with beams  119 , which beams  119  may be hollow to enhance buoyancy of the resulting different types of assemblies. 
       FIG. 7  shows how two floating carriers  6  can be placed mutually abutting with their respective end surfaces  60 ,  61 , for instance for processing at stations  17 ,  18 ,  19  in  FIG. 1 . Adjacent growth locations are arranged along at least one beam  52  of one floating carrier  6  at the same intermediate distance a. The growth locations  7  positioned at opposite ends of floating carrier  6  are each arranged a shorter distance k, 1 than the intermediate distance a from the relevant end  60 ,  61  of floating carrier  6 . The distances k+1 from growth locations  7  at opposite ends  60 ,  61  of floating carrier  6  to the relevant ends  60 ,  61  of floating carrier  6  are equal to the intermediate distance a. In the example shown in  FIG. 7  this distance k, 1 is made equal to a/2. 
       FIGS. 8 and 9  show an alternative embodiment of two similar floating carriers  62 , each with three beams  63 ,  64  closed all the way around.  FIG. 8  shows a cross-sectional view with adjacent floating carriers  62 . Clearly shown here is that rows of growth locations  7  between adjacent beams  63 ,  64  are located at mutual intermediate distances b. Shown in  FIG. 9  is a head-to-tail orientation of adjacent floating carriers  62  which is for instance highly suitable for mechanical processing. The same property is shown to apply here as that described with reference to  FIG. 7  for intermediate distances a″ between growth locations  7  in each row. It is additionally noted that each floating carrier  62  has two rows of growth locations  7  and that the same properties as those described with reference to  FIG. 7  also apply for the intermediate distances between growth locations  7  in adjacent rows, this being indicated with intermediate distances a′. Connecting lines  65  between adjacent growth locations  7  in adjacent rows enclose in each case an angle α. The width of the central beams  64  is larger, in the embodiment shown in  FIG. 8  twice as large, as the width of the outer beams  63 . For the parameters of the width of the beams, the angles enclosed between connecting lines  65 , the distance b between rows of growth locations  7  and so on, other ratios can also be envisaged in order to provide constant mutual distances between the rows, growth locations  7  in each of the rows and constant mutual distances between growth locations  7  in adjacent rows, even over end surfaces of floating carriers  6  in head-to-tail arrangement. In the embodiments shown here distances between growth locations  7  at an end surface of floating carriers  6  and a related end surface have been mentioned of a/2, as also referred to in  FIGS. 7, 8 and 9 , but it will be apparent that many other additional or alternative configurations are likewise possible in order to realize the desired continuous mutual intermediate distances between growth locations  7 , even over separations between floating carriers  6  lying parallel adjacently of each other and over floating carriers  6  positioned head-to-tail. 
     After examination of the foregoing description of specific examples of embodiments within the scope of the present invention many additional and alternative embodiments will occur to the skilled person, which are not specifically disclosed here. The scope of protection for the present invention is in no way limited to the specific examples in the foregoing description and the accompanying drawings and is only limited by the specific or similar features as defined in the appended claims and shown and disclosed herein above. In particular, any one or more than one of: the suction or vacuuming system; the watering system and the UV illuminating system; the water supplying system; and the air and more preferably oxygen supplying system; the carrier lifting and lowering devices, and the like, may be implemented in a different embodiment of a hydroponics based cultivation system even without the circulatory transport system for promoting the floating carriers around the pond or basin. Likewise, shapes and forms of floating carriers may differ from the explicitly shown embodiments, and can be implemented even in environments separate from the circulatory transport system for promoting the floating carriers around the pond or basin.