DESCRIPTION The present invention, according to a first aspect thereof, relates to a cultivating bed for mushrooms, comprising a permanent supporting surface and a temporary supporting surface which is movable with respect to the permanent supporting surface, on which a temporary culture medium for mushroom cultivation is present in use. Such a cultivating bed is known. The known cultivating bed forms part of a rack comprising standards which support a number of horizontally extending cultivating beds disposed one above the other. The known cultivating bed has a grating as the permanent supporting surface, over which a cloth forming a temporary supporting surface is drawn, on which the culture medium consisting of compost with spawn and supplementary nutrient for mushrooms to be cultivated is present. Disposed under the permanent supporting surface is a layer of a thermal insulation material, which functions to prevent heat being transferred from the cultivating bed to the environment at the bottom side of the cultivating bed. The culture medium is usually covered with casing soil. A known cultivating bed for cultivating mushrooms is filled with about 90 kg/m ² culture medium and about 400 l/m ² casing soil. During a period of a few weeks, mushrooms are cultivated and harvested from the culture medium. After some time, the activity of the culture medium is no longer sufficient for an economically efficient cultivation, and the cloth with the culture medium and the casing soil present thereon is pulled off the permanent supporting surface. A new cloth with new culture medium is then drawn over the grating. Subsequently, said cloth is moved forward and backward over the permanent supporting surface like a conveyor belt, with the culture medium being discharged and new culture medium subsequently being deposited on the cloth.

A drawback of the known cultivating bed is that the activity of the culture medium decreases relatively quickly and needs to be replaced relatively soon, so that only a limited part of the cultivating capacity contained in the culture medium can be utilised for cultivating mushrooms in an economically efficient manner before the culture medium needs to be replaced.

Accordingly it is an object of the present invention, according to the first aspect thereof, to provide a cultivating bed as described in the introduction, by means of which a greater part of the capacity of the culture medium can be utilised for cultivating mushrooms in an economically efficient manner. According to the present invention, this object is accomplished in that temperature control means for controlling the temperature of the temporary culture medium that is present in use are disposed under said temporary culture medium, which temperature control means are at least partially surrounded by insulation material. Using the temperature control means, the temperature of the culture medium can be controlled such that more mushrooms per kilogram of culture medium can be cultivated. This applies in particular in the case of the first flush, when an up to 25% higher yield can be realised. It has been found that when such temperature control is used, less culture medium, in favourable cases about 50% less culture medium, is needed in comparison with a known cultivating bed where such temperature control means are not used. Moreover, replacement of the culture medium is needed less quickly in comparison with the known cultivating bed. Because of the temperature control, active substances contained in the culture medium can be activated to a sufficient degree for a longer period of time than in the known cultivating bed. Put differently, mushrooms can still be cultivated in an economically efficient manner when the concentration of spawn and supplementary nutrient in the culture medium is relatively low. The insulation means make it possible to effect an efficient supply and discharge of heat. Thus it is possible have the temperature control means free at locations where an effective heat transfer between temperature control means and culture medium can be realised, i.e. between insulation material and a culture medium disposed above said insulation material. Other parts of the temperature control means can be surrounded by insulation material, where possible, so as to limit the transfer of heat between the temperature control means and the environment. The object of the present invention is thus realised.

In the above the amount of culture medium needed for cultivating mushrooms has been discussed. In general it can be stated, however, that a saving of 1/3 to 1/2 of the culture medium can be realised with other types of fungi as well.

In cultivating spaces for mushrooms, heating means will already be present, however. Said means are air heating means, however, and the temperature of a cultivating bed is maintained at a constant level by the hot ambient air, which influences the temperature of the culture medium to a much lesser extent, and that with a relatively long delay. Moreover, the ambient air is only to a limited extent suitable for influencing the temperature of the culture medium, because requirements are made also of the ambient air in which the mushrooms grow, such as a limited suitable temperature range and a minimal air displacement. Because of the aforesaid limited influence and the delay that occurs, the heating system device for heating the air cannot be regarded as a temperature control device. In any case, said air heating device does not extend under the temporary culture medium that is present in use.

In a preferred embodiment of the present invention, the insulation material comprises a plate-shaped insulation element, in which temperature control means are at least partially accommodated. Thus, fluid lines may extend at the upper side of the plate-shaped insulation element, for example, in which case the upper side of the fluid lines is kept clear for giving off and/or absorbing heat to and from, respectively, the culture medium. This is a simple solution with adequate insulation to prevent transfer of heat between the temperature control means (fluid lines) and the air in the cultivating space.

Alternatively, the temperature control means comprise temperature control elements, with individual temperature control elements being partially surrounded by separate insulation elements. Thus, fluid lines functioning as temperature control elements can extend under the culture medium, for example, being surrounded in part by insulation material having a C-shaped cross-section, with the opening being located at the upper side, at least facing the culture medium. Thus, less insulation material is needed for fitting out a cultivating space.

To realise a good heat transfer between the temperature control means and the culture medium, the temporary supporting surface is preferably connected to the temperature control means. Said connection may be a direct or an indirect connection, for example via the permanent supporting surface.

It is preferable if the temperature control means are at least partially disposed between the permanent supporting surface and the insulation. The temperature control means can thus heat or cool the culture medium via the supporting surface. If the permanent supporting surface is provided with air passages, in particular if the permanent supporting surface is a grating, a very efficient and direct transfer of heat can take place between the temperature control means and the culture medium. The insulation material can prevent heat being transferred in a different direction or from a different direction.

In a preferred embodiment of the present invention, the temperature control means comprise a fluid line which extends at least partially under the temporary culture medium. An (empty) space is present under the temporary culture medium, in which space the fluid line can extend. If insulation material is provided under the fluid line, radiation heat from the fluid line is prevented from influencing the temperature in a cultivating bed disposed at a lower level.

In order to be able to realise an adequate control of the temperature of the culture it is preferable if the temperature control means are suitable for giving off heat to and absorbing heat from the culture medium. Because the culture medium for mushroom cultivation may start to ferment, it is important not only that the culture medium can be heated but also that the culture medium can be cooled.

In order to be able to set the temperature control means correctly, it is preferable if temperature sensors are provided for measuring the temperature of the culture medium. The temperature in the culture medium can be influenced by factors which are very difficult to control, if at all. Temperature sensors can contribute to a quick response of the temperature control _. means to temperature changes in the culture medium.

The temporary supporting surface preferably comprises a cloth. A cloth, for example a nylon cloth, provides a suitable supporting surface for the culture medium and, moreover, is suitable for realising an advantageous heat transfer between the temperature control means present under the cloth and the culture medium.

According to a second aspect, the present invention relates to a cultivating device for cultivating mushrooms, comprising at least one closable space provided with at least one rack with a permanent supporting surface and means for arranging a temporary supporting surface supporting a temporary culture medium for mushroom cultivation over said permanent supporting surface. Such a cultivating device is known, it comprises a cultivating bed of the previously discussed known type. According to the second aspect, it is an object of the present invention to provide a cultivating device by means of which a larger part of the capacity of the culture medium can be utilised for cultivating mushrooms in an economically efficient manner. According to the present invention, this object is accomplished in that temperature control means are disposed under the temporary culture medium that is present in use, which control means function to control the temperature of the culture medium. The advantages of such a device are analogous to the advantages that have been discussed with reference to the first aspect of the present invention.

It is preferable in that regard if a cultivating device comprising a cultivating bed according to the first aspect of the present invention is used.

It is moreover preferable if the temperature control means comprise a fluid line which extends at least partially under the temporary culture medium.

The temperature control means preferably comprise a heat source and a cold source, whilst a heat exchanger is provided between said heat source and/or said cold source on the one hand and said fluid line on the other hand. Heat that has been extracted from the cultivating bed via the temperature control means can thus be stored via a heat exchanger.

According to a third aspect, the present invention relates to a method for cultivating mushrooms, comprising the steps of: a) providing a closable space comprising at least one permanent supporting surface; b) arranging a temporary supporting surface supporting a culture medium for mushrooms over said at least one permanent supporting surface; c) having mushrooms grow under controlled conditions in said space; d) harvesting mushrooms; and e) removing the temporary supporting surface and the culture medium present thereon when the activity of the culture medium decreases. The above step c) is a continuous process, which in principle takes place uninterruptedly between step b) and step e). As a rule, step d) is carried out several times in the course of step c).

Such a method is known, it has the drawback however, that controlling the temperature in the culture medium is only possible to a limited extent. In fact this mainly happens indirectly as a result of the climate in the space in question being controlled, which compensates for temperature fluctuations that occur in the culture medium as the degree of fermentation thereof varies. Accordingly it is an object of the present invention to provide such a method, which provides an improved temperature control in the culture medium in comparison with the known device. This object is accomplished by the present invention in that the temperature of the culture medium is controlled in step c) by using temperature control means disposed under the temporary supporting surface. The advantages of such a method have already been discussed in the foregoing in relation to the aforesaid devices according to the first and the second aspect of the present invention. It is preferable to use a cultivating bed according to the first aspect of the present invention in said method. The advantages of said cultivating bed have already been discussed in the foregoing as well, as have the advantages of a preferred method in which the temperature of the culture medium is increased or decreased by means of fluid flowing through pipes extending at least partially under the culture medium.

The present invention will be discussed in more detail below with reference to the appended figures, in which:

Figure 1 is a longitudinal sectional view of a cultivating bed according to the present invention; and Figure 2 is a schematic view of a temperature control system for a cultivating device according to the present invention.

Figure 1 shows a cultivating bed 1 for mushrooms. The cultivating bed 1 comprises a number of standards 2, between which longitudinal girders 3 extend. Between said longitudinal girders, cross-sections 4 having an inverted U- shape extend under a layer of insulation material 5, at the upper side of which recesses 6 are provided, through which pipes 7 for water extend in the transverse direction, which pipes interconnect two pipes (not shown) extending in the longitudinal direction on either side of the cultivating bed 1. A grating 8 extends above the insulation material 5 and the pipes 7, which grating is attached to the standards 2. A nylon cloth 9 is drawn over the grating 8, on which cloth a layer of culture medium 10 covered with casing soil 11 is present, in which mushrooms 12 grow. Edge planks 13 extend between the standards 2 both in the longitudinal direction and in the transverse direction of the cultivating bed 1.

Figure 2 is a schematic overview of a heating/cooling system 21 according to the present invention, comprising a heat source 22 and a cold source 23 with respective supply lines 24, 25 and return lines 26, 27 to and from, respectively, a heat exchanger 28. The supply lines 24, 25 are provided with thermostatic valves 29, 30. The return lines 26, 27 are provided with immersion sensors 31 and 32, respectively. A circulation pipe 33 for the heating/cooling system for the cultivating beds (not shown in figure 1) is connected to the heat exchanger. The circulation pipe 33 is in communication with an expansion vessel 34 and a de- aerator 35 and is connected to a circulation pump 36, which pumps fluid from the circulation pipe 33 via a distributor 37 and ball valves 38 to pipes 39 through respective cultivating beds (not shown). Via control valves 40 the heating or cooling water flows to a collector 41 and then back to the heat exchanger 28 via the circulation pipe 33. The distributor 37 is provided with an overflow valve 42, and the collector 41 is provided with a fill and drain cock 43.

With reference now to figure 1 , the nylon cloth 9, which functions as a temporary support for a temporary culture medium consisting of 45 kg/m ² culture medium 10 and 4-5 cm of casing soil 11 , is supported by the grating 8. When the culture medium can no longer be sufficiently activated or, in other words, no longer functions satisfactorily, for profitably cultivating mushrooms 12, i.e. when the culture medium contains (too) little spawn and/or supplementary nutrients, the nylon cloth 9 and the culture medium and any remaining mushrooms 12 is pulled off the grating 8 of the cultivating bed. The culture medium on the nylon cloth is then substituted for about the same amount of culture medium 10 and casing soil 11 and drawn over the grating 8. The activity of the culture medium depends on the concentration of enzymes in the culture medium 10 and the temperature of the culture medium 10. The cultivating bed 1 is usually disposed in a closed, conditioned space, but because the culture medium 10 tends to start fermenting, the temperature of the culture medium 10 is a factor which is difficult to control if adequate control means are not available. In connection therewith, resistance sensors 14 have been manually inserted into the culture medium 10 after filling of the nylon cloth, which sensors send temperature information to the control device over wires (not shown). On the basis of the temperature information from the resistance sensors 14, the control device determines whether the temperature in the culture medium must be adjusted upwards or, on the contrary, downwards. The control device then determines the desired temperature of the water that is to be passed through the pipes 7 (39 in figure 2). Hot water will give off heat from the pipe 7 in upward direction, which heat will be absorbed by the culture medium 10. Although the pipes 7 are shown spaced from the grating 8 in figure 1 , it is preferable with a view to effecting a good heat transfer for the pipes 7 to make direct contact with the grating 8. If, on the other hand, the culture medium 10 is (too) hot, a cooler fluid will be passed through the pipes 7, and water flowing through the pipes 7 will absorb heat, thereby cooling the culture medium 10. The temperature control can be supported by information about the temperature of water supplied to the cultivating bed 1 and of water discharged from the cultivating bed. Moreover, infrared cameras may be mounted above the cultivating bed 1 for measuring the surface temperature of the cultivating bed 1. This information, too, can be supplied to the control device as feedback for determining or adjusting the desired temperature of the water to be supplied to the pipe under the cultivating bed 1.

The control device may be set for controlling the temperature of an entire cultivating bed, but it is also possible for the cultivating bed to be divided into compartments, so that the temperature of the cultivating bed can be controlled for each compartment individually. The influence of the fermentation of the culture medium on the temperature can vary locally in a cultivating bed.

The temperature of the culture medium 10 is thus controlled to make an optimum cultivation of mushrooms 12 possible. It is not always necessary to aim at a temperature that is optimal for mushroom cultivation. It is also possible to control the temperature such that it can be determined in advance that the mushrooms 12 will be ready for harvesting at a specific moment. Logistic advantages can be realised by actively controlling the degree of growth using the heating/cooling system. Furthermore, a higher yield can be realised from a comparable amount of culture medium 10 in comparison with a known system in which temperature control does not take place, because the culture medium can be utilised longer in an economically efficient manner than with the known cultivating beds. The heating/cooling system shown in figure 2 is self-explanatory and does not require further elucidation.

In the foregoing a preferred embodiment of the present invention has been described merely by way of example. It should be understood that various variants thereof, which may or may not be obvious to those skilled person, are conceivable within the scope of the present invention, which is defined in the appended claims. Thus, the description is focussed on the cultivation of mushrooms, but it is also possible, of course, to cultivate other types of fungi in a comparable cultivating bed. A different type of culture medium or a different proportion between culture medium and casing soil on the nylon cloth may be used in that case. At present nylon cloth is frequently used for cultivating beds of mushrooms, but it should be understood that cloths of different materials may be used as well. The pipes that extend under the cultivating bed need not be accommodated in the recesses of insulation material. The advantage of using fluid lines disposed under the grating on which the nylon cloth is supported is that the fluid lines cannot easily be damaged when the nylon cloth with the culture medium is exchanged. In this document a hot/cold water pipe has been described by way of example for transporting heat/cold. It is also possible to use another suitable fluid instead of water. It is even possible to transport heat and cold in a different manner than through fluid lines to and from the cultivating bed, for example via radiation.