WATER-ABSORBING POROUS PRODUCT FOR THE CULTIVATION OF PLANTS AND METHOD FOR THE CULTIVATION OF PLANTS BY MEANS OF A WATER-ABSORBING PRODUCT

Abstract: The invention relates to a water-absorbing porous product made of water-absorbing mineral fibrous material for the cultivation of plants. Said product comprises water-repellent oxygen-storing elements which are able to release oxygen in a delayed manner to a liquid sucked up into the porous product. Said elements preferably form at least one layer (2) between two layers (3,4) of water-absorbing mineral wool. The layer of water-repellent oxygen-storing elements is preferably at least partially in contact with the outside air. The invention also relates to a method for the cultivation of plants using the water-absorbing product according to the invention.

Description: The invention relates to a water-absorbing porous product made of water-absorbing mineral fibrous material for the cultivation of plants, preferably in the form of a block. A product of this type is known. This known product, in the form of small blocks, consists of mineral wool fibres treated with a binder and a wetting agent. Through the introduction of a wetting agent a readily wettable product is obtained which can absorb a suitable quantity of water and distribute it by capillary forces over the volume of the product. The binding agent provides for the preservation of the shape and structure of the mineral wool fibrous product. Said known product therefore has the capability of retaining water, and to a lesser degree air as well, in a uniform and fine distribution. Said known product presents the drawback that immediately after the product is wetted all the oxygen as present is expelled by the liquid sucked up into the product, as a result of which too little or no oxygen can be supplied to the plant roots which form during cultivation of a plant in a water-absorbing porous product of this type. This will effect the growth of a plant involving a reduced yield of the particular plant. The object of the invention is therefore to provide a water-absorbing porous product in which oxygen is always present in the product wetted with water after the first wetting. This object is achieved according to the invention in that the porous product contains at least one water-repellent oxygen-storing element. Preferably said element or if more elements are present at least a part of said elements are in contact with the outside air. Said elements are preferably such that they are able to release oxygen in a delayed manner to a liquid sucked up into the porous product. The presence of water-repellent oxygen-storing elements of this type has the result that after the first wetting of the water-absorbing porous product regions continue to exist in which oxygen is located which can be released in a delayed manner to the liquid absorbed in the porous product so that sufficient oxygen can always be supplied to the roots and an excellent growth is therefore quanranteed. The oxygen-storing, preferably also porous, water-repellent elements preferably form at least one zone, preferably layer in the porous product between two layers of water-absorbing mineral wool. Expediently the oxygen-storing elements are water-repellent porous elements such a elements made of foam plastics with open cells or porous water-repellent flakes of fibrous material. Preferably use is made of water-repellent flakes of mineral wool fibres which form a very cheap product. If the oxygen-storing water-repellent elements form one or more layers between two layers of water-absorbing mineral wool, it is possible to provide oxygen or air at the desired height in the correct quantity. At the same time the volume of the water-repellent elements can obviously be varied for various heights within the water-absorbing porous product, while the thickness of the water-repellent elements in the layer may itself also vary. According to another preferred embodiment groovelike recesses are present in the porous product which contain, at least in part, oxygen-storing, preferably also porous, water-repellent elements. Said embodiment also guarantees that a sufficient quantity of oxygen can be supplied to the roots of the plant to be cultivated. The invention also relates to a method for the manufacture of a water-absorbing porous product from water-absorbing mineral wool for the cultivation of plants, mineral wool fibres being treated with a wetting agent and the treated wool fibres being formed into a blanket, which method is characterized in that there are incorporated in the porous product water-repellent oxygen-storing elements which are able to release said oxygen in a delayed manner to a liquid sucked up into the porous product. The formation of the blankets takes place in a manner known per se by forming the mineral wool fibre material borne by an air stream and treated with a wetting agent into a porous layer. By supplying the oxygen-storing porous elements, in a manner which may or may not be uniform, to the air stream containing the water-absorbing porous mineral fibre material a distribution, which may or may not be uniform, is obtained of said oxygen-storing elements in the porous layer to be formed. Preferably oxygen-storing elements are provided layerwise in the product to be formed in view of the fact that it is sufficient in this connection to pour the water-repellent oxygen-containing elements onto a layer of the water-absorbing material and then to fold said layer once or several times so that a final product is obtained which contains one or more layers of the water-repellent porous elements. In that case a porous layer of water-absorbing mineral wool fibres is first formed after which a layer of oxygen-storing porous elements is provided on the layer formed in this manner. By turning the double layer formed over once or several times a product is obtained which contains one or more layers of oxygen-storing porous elements between layers of water-absorbing mineral wool. The finished product preferably has the shape of a small block. A shape of this type self-evidently offers advantages during transport and storage as a result of the good stackability and in addition, the product is then available in the shape finally used. The oxygen-storing water-repellent elements may, The oxygen-storing water-repellent elements may however, also be provided in groove-like recesses. Preferably the water-repellent oxygen-storing elements are provided in a manner such that they are in contact with the outside air. The invention also relates to a method for the cultivation of plants using a water-absorbing porous product according to the invention. The invention will now be explained on the basis of an exemplary embodiment by means of the drawing in which: Figure 1 shows a block-shaped water-absorbing porous product according to the invention; Figure 2 is a section of a water-absorbing porous product of this type according to the invention in which there are several layers of oxygen-storing elements situated at a distance from each other; Figure 3 is another embodiment of a water-absorbing porous product according to the invention in which the oxygen-storing elements are wedge-shaped; Figure 4 is yet another embodiment of a water-absorbing porous product according to the invention with oxygen-storing elements provided in a groove-like recess; Figure 5 shows a diagrammatically represented device for the manufacture of a water-absorbing porous product according to the invention; Figure 6 is a cross-section of a strip obtained as in Figure 5 of mineral fibrous material on which there are water-repellent oxygen-storing elements, which strip has been folded in a suitable manner to form water-absorbing porous products into a block shape as in Figures 1 or 2; Figure 7 is a cross section of a strip, not yet folded, obtained as in Figure 5 for the manufacture of a water-absorbing porous product as in Figure 3, and Figure 8 shows diagrammatically and in perspective a possible device for the shaping of the strip as in Figure 7. Figure 1 shows a small block 1 of a water-absorbing porous product consisting of a water-absorbing mineral fibrous material, in particular mineral wool. Between the underside 3 and the upper side 4 of a small block 1 there is embedded inthe water-absorbing mineral wool product a layer 2 of water repellent mineral wool flakes. As a result of the porous structure of said water-repellent mineral wool flakes there is a quantity of air in said flakes which is able to supply oxygen to the roots which are produced in a small block of this type when it is desired to cultivate a plant in a small block of this type. Suitable plants are, for example, various flowering plants, cucumbers, strawberries and the like. Instead of water-repellent mineral wool flakes use may also be made, for example, of foam plastics with open cells such as, for example, polystyrene foams, which are water-repellent per se and retain air in their pores, for forming the intermediate layer 2. When the small block 1 is placed in a trough through which a plant nutritive medium is flowing, said plant nutritive medium will be taken up immediately by the water-absorbing porous small block 1 and will expell air from said water-absorbing porous product. This would mean that thereafter virtually no air would be present any longer in the small block and no oxygen is therefore available for supplying to the plants which form in the small block during the cultivation of a plant. The invention overcomes this drawback by the provision of the said layer 2. Figure 2 shows an embodiment in which there are layers 2a, 2b and 2c of water-repellent oxygen-storing elements of this type in the form of water-repellent mineral wool flakes, at various heights in the small block. The layers 2a, 2b and 2c open into the outside air so that continuously air is able to penetrate into said layers. As a result of this, during the cultivation process oxygen can always be made available to the roots which penetrate further into the small block. In view of the increase in the number of roots during the further course of the cultivation, it is advisable for the lowermost layer 2c of the water-repellent oxygen-storing elements which are nearest the bottom of the small block 1 to be constructed more thickly than the layer 2a being situated nearer the top of the small block 1. An essential feature of the invention is that the water-repellent elements such as foam plastics blocks with open cells or water-repellent flakes of mineral fibres retain a quantity of oxygen when fluid penetrates through the entire small block 1. Figure 3 shows another embodiment in which wedgeshaped water-repellent oxygen-containing elements 5a to 5d incl. are present in the small block between the water-absorbing porous layers. This wedge shape promotes the absorption of oxygen from outside and better root hair formation. The wedge-shaped layers may, if desired, become thicker towards the bottom of the small block and/or extend up to the top of the small block. Figure 4 shows yet another embodiment in which the small block is provided at the bottom with a groove-like recess 6 in which water-repellent oxygen-storing elements 7 are provided, as a result of which sufficient oxygen is always available. Figure 5 shows diagrammatically a device for the manufacture of a strip of water-absorbing porous product made of water-absorbing mineral fibrous material with water-repellent oxygen-storing elements provided thereon in the form of water-repellent fibres of mineral wool. From a diagrammatically shown melting furnace 8 molten mineral product is brought via a feed device 9 onto a rotating roller 10, which mineral product is hurled by the rotating roller 10 from this point to form mineral wool fibres which deposit as a uniform strip 11 of water-absorbing mineral wool which is supported by an endless belt 12. From a feed 13a layer 14 of water-repellent mineral wool fibres is provided on the strip 11. Said strip may yield small blocks 1 by folding together and cutting out. Figure 6 shows diagrammatically a strip of water-absorbing mineral wool 11 folded together several times on which a layer 14 is provided of water-repellent flakes of mineral wool. Said strip has been folded several times in a zigzag fashion, after which small blocks 1, such a shown in Figure 1, can be cut out a strip of this type along the broken lines 15. It will be clear that in the embodiment shown in Figure 6 the layers of water-repellent oxygen-storing elements can nevertheless be given different thicknesses by making use, for example, of several feeds 13, as a result of which an additional layer of the water-repellent elements can be provided. It is also possible to provide via a feed 13 a layer 14 of mineral wool fibres made water-repellent only on a section of the strip 11 of water-absorbing mineral wool, the cross-section of the layer 14 being wedge-shaped as is shown in Figure 7. A strip of this type is used to manufacture the water-absorbing porous small blocks shown in Figure 3 with wedge-shaped oxygen-storing elements. Figure 8 shows diagrammatically how from a strip of this type a folded-together strip can be obtained from which the small blocks as in Figure 3 can be cut. The strip 11 coming off the endless belt 12 with the layer 14 provided thereon is first passed over, for example, a rod-shaped element 16 which is at an angle of approximately 45° with respect to the longitudinal direction of the endless belt 12. The strip which is then hanging downwards is then given a zigzag form by reciprocating elements 17 and 18 and laid in roof-tile fashion on a second endless belt 19 which is approximately at an angle of 90° with respect to the first belt 12 and which removes the folded strip 20 sideways. The giving of a zigzag form to the strip 11 may, of course, take place by means of a reciprocating fork-shaped element, the strip 11 passing between the legs of the fork. The small blocks such as shown in Figure 3 are finally cut from the strip 20.

Claims: 1. Water-absorbing porous product made of water-absorbing mineral fibrous material for the cultivation of plants, preferably in the form of a block, characterized in that the porous product contains at least one water-repellent oxygen-storing element. 2. Water-absorbing porous product according to claim 1, characterized in that the water-repellent oxygen-storing element is able to release oxygen in a delayed manner to a liquid sucked up into the porous product. 3. Water-absorbing porous product according to claim 1 or 2, characterized in that oxygen-storing preferably also porous, water-repellent elements form at least one layer in the porous product between two layers of water-absorbing mineral wool. 4. Water-absorbing porous product according to claim 1-3, characterzed in that several layers of oxygen-containing water-repellent elements, situated at a distance from each other are incorporated in the porous product, preferably the distance between layers of water-repellent elements being matched to the plants to be cultivated. 5. Water-absorbing porous product according to claims 1-4, characterized in that layers of water-repellent elements are situated at equal distances from each other. 6. Water-absorbing porous product according to claims 1-5, characterized in that the volume of the oxygen-storing water-repellent elements provided in a layer increases in the direction of the surface which is the last to come into contact with the roots of a plant to be cultivated. 7. Water-absorbing porous product according to claims 1-7, characterized in that the number and the thickness of the successive layers of oxygen-storing elements is chosen depending on the plant to be cultivated. 8. Water-absorbing porous product according to claim 1 or 2, characterized in that the porous product comprises groove-like recesses which contain at least in part oxygen-storing, preferably also porous, water-repellent elements. 9. Water-absorbing porous product according to claims 1-8, characterized in that the water-repellent porous elements consist of water-repellent flakes of mineral wool. 10. Water-absorbing porous product according to claims 1-10, characterized in that the water-repellent oxygen-containing elements are at least partially in contact with the outside air. 11. Method for the cultivation of plants using a water-absorbing porous product, characterized in that a product according to claims 1-11 is used.

Inventors: BLOK, CHRISTIAN, IR.
Applicants: ROCKWOOL LAPINUS B.V.
Application year: 1986
Main classification: A01G31
IPC codes: A01G31