GB2163419A

GB2163419A - Controlled release nutrients

Info

Publication number: GB2163419A
Application number: GB08517801A
Authority: GB
Inventors: Gordon David Lawson; Donald Bird
Original assignee: Caligen Foam Ltd
Current assignee: Caligen Foam Ltd
Priority date: 1984-07-20
Filing date: 1985-07-15
Publication date: 1986-02-26
Also published as: GB8418622D0; GB8517801D0; GB2163419B

Abstract

A horticultural nutrient product comprises a porous substrate impregnated with a product incorporating a nutrient composition dispersed in a water soluble carrier. The product is preferably a sheet of open celled foam plastics material such as polyurethane foam impregnated over its entire area and through at least part of its thickness. The water soluble carrier is preferably a wax material such as a fatty acid ethoxylate. The product is used by placing it around growing plants on the soil or other growing medium.

Description

SPECIFICATION Horticultural nutrient product This invention relates to a horticultural productfor use in providing nutrients in the cultivation of plants, shrubs and trees.

It is an object of the invention to provide a product which will provide controlled release of nutrient composition to growing plants and the like over an extended period.

The invention provides a horticultural nutrient product comprising a porous substrate impregnated with an impregnant consisting of or incorporating a nutrient composition dispersed in a water soluble carrier.

Preferably the substrate comprises a sheet of open celled foamed plastics material such as polyurethane foam. Advantageously the substrate comprises polyesterurethane foam.

The substrate is preferably uniformally impregnated over its entire area and through at least part of its thickness.

The impregnant may incorporate a fungicide and a rooting stimulant in addition to said nutrient composition.The formulation may comprise 1-7% rooting stimulant, 3-10% fungicide and the balance nutrient composition.

Preferably said nutrient composition and said fungicide and rooting stimulant, if provided, comprise a powder or blend of powders dispersed in said carrier.

The carrier is preferably a wax material and may comprise any water soluble low toxicity wax of suitable melting point which is preferably biodegradable. Suitable wax compositions comprise fatty acid ethoxylates such as polyethylene glycol monostearate. The impregnant preferably comprises 9010% by weight of a nutrientlfungicide/rooting composition and 10-90% by weight of wax carrier.

Preferably the ratio of impregnant to substrate is between 2:1 and 10:1 by weight.

The product may be used by placing it around growing plants on the soil or other growing medium.

For this purpose the product is preferably of annular form having a central hole to receive the trunk or stem of the plant and a radially directed slit to enable placing of the product around the plant or tree.

Alternatively the product may be placed beneath a pot or similar container in which plants are growing.

In such cases the product may advantageously be of circular shape and the fungicide and rooting stimulant may be omitted.

The impregnant is preferably introduced into the substrate in a melted condition while the substrate is compressed, the substrate being subsequently allowed to expand, thereby creating a vacuum within the structure of the substrate which draws the impregnant into and disperses it through the structure. This ensures uniform impregnation and hence uniform release of the nutrient composition during use.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure lisa plan view of one form of plant feeding device according to the invention; and Figure 2 is an end view of the product shown in Figure 1.

Referring to the drawings, there is shown a plant or shrub collar comprising a sheet 5 of polyesterurethane foam of generally annular form having a central aperture 6 and a generally radially extending slit 7 connecting the central aperture 6 to the outer edge of the collar. The collar may advantageously be from 10-35cm. in diameter and from 1-5 mm thick and the slit 7 enables the collar to be opened, placed round the stem of a shrub or other plant, and then positioned in a spread or flattened condition over the surface of the soil around the plant. The slit 7 is provided with an arcuate portion 7A intermediate its ends forming a locating tab 7B to facilitate engagement of the two parts o the collar after placement around the plant.

The sheet 5 is impregnated with an impregnant comprising a nutrient composition in the form of a powdered mixture containing a nutrient, a fungicide and a rooting hormone, and a wax carrier in the form of a polyethylene glycol monostearate in which the nutrient composition is dispersed. In a preferred form the nutrient composition comprises 90% nut rient, 4% rooting powder and 6% fungicide, although these proportions may be varied quite considerably dependent on requirements. The impregnant preferably comprises 10-90% by weight of the wax carrier and 90-10% by weight of the nutrient composition.

The rate of release of the nutrient composition is dependent on the moisture content of the soil, the amount of rainfall and the degree of water solubility of the wax carrier. It is envisaged that generally the water solubility of the wax carrier will be selected such that over an average years rainfall in the country in which the product is to be used all of the nutrient composition will be uniformally released.

The wax carrier must therefore have the correct water solubility to enable release of the nutrient composition at the desired rate and must be of low toxicity and preferably biodegradable. The melting point of the wax is preferably higher than 45" C, in order to withstand the maximum temperatures iikely to be encountered during warm weather, but must be lower than the temperature at which the nutrient composition will commence thermal degradation.

In production of one example of the product, a web of polyester-urethane foam 4mm. thick having a weight of 112 gm/m2 and a density of 28 kg/m3 and having 18 to 22 cells per linear centimetre, was passed at a speed of 35 metres per minute through nip rollers serving to compress the foam so as to expel air thereform. The nip-rolls also served as applicators to apply impregnant at the foam, the impregnant being applied to a temperature of 45"C to 55"C and preferably 50"C, and the ratio of impregnanttofoam comprising 4:1 by weight.After passing through the nip-rolls the foam was allowed to expand to its normal dimensions thereby drawing the melted impregnant into the cells of the foam and was then cooled to 25"C by forced air draught at ambient temperature. The foam was then cut into sections of the desired size and provided with slits to enable its use in the manner previously described.

The extent to which the foam is impregnated may be varied dependent on the nature of the foam, the rate of movement of the foam through the impregnating apparatus during treatment, the impregnant employed and the degree of compression, but the degree of compression is preferably such that on subsequent expansion the impregnant is drawn into the foam structure so as to be substantially uniformally dispersed throughout its cross-section. The foam structure in effect acts as a reservoirforthe impregnant, the nutrient component of which is subsequently released in a uniformally controlled manner when the product is wetted by rainfall or artificial watering.

Application of the nutrient composition in hot melt form is particularly advantageous in that there is no need to apply subsequent heat treatment for the purpose of driving off water of solution or the like and increased production speed and saving in energy can therefore be achieved. Moreover acceleration of cooling of the treated substrate may be effected by passing it through a refrigerated zone thereby enabling still further increases in production speed and consequent savings to be achieved.

A particular advantage of the use of an impregnant comprising a nutrient composition in a wax carrier is its ability to be gradually released due to the wax component being sparingly soluble. The provision of the slits or other openings for engagement around the plant enable the product to feed the roots below uniformly and because of the thin nature of the substrate the product can be produced relatively cheaply.

In an alternative embodiment the product may be cut into circular pieces for placing under plant pots or the like, in which case the nutrient composition is released and drawn into the pot by capillary action.

Forthis purpose the composition preferably contains a higher nitrogen containing nutrient composition than would be employed in the case of the ground surface collar and the fungicide and rooting stimulant may be omitted.

In the case of either embodiment the impregnant need not be dispersed throughout the thickness of the substrate by may be confined to a region adjacent one or other surface. In such a case the impregnant will be dispersed uniformly over the area of the substrate but will not be dispersed throughout its cross-section. A modified product of this kind generally has an improved aesthetic appearance compared with a fully impregnated product, processing and packaging problems caused by faces of the treated material sticking together are reduced, and the untreated face may be subjected to further processing, for example application of printing. The product will normally be used with the impregnanted face directed downwardly.

In the case of a partially impregnated product the impregnant may be applied in the same manner as described previously and the depth of impregnation may be controlled by appropriate selection of the carrier and by the impregnating conditions. The viscosity of the melted wax or other water soluble composition to be impregnated into the substrate may be controlled by the temperature of application, the type of wax used and the ratio of nutrient composition to wax. The viscosity may be increased by reduction in the temperature of application, by increase in the melt viscosity of the wax selected, or by an increase in the ratio of nutrient composition to wax in which it is dispersed. An increase in viscosity will reduce the depth of impregnation. The depth of impregnation may be increased by increasing the time during which the substrate is under compression during the impregnating process which may be effected by reducing the rate of throughput of the machine.

Various modifications may be made without departing from the invention. For example while polyurethane foam is preferred as the substrate other foamed plastics materials, non-woven fabrics or other porous materials may be used as the substrate. The product may contain a number of openings of slit or other form to enable it to be maintained in a flat condition during use and the thickness and construction of the substrate and the nature of the nutrient composition and carrier may also be varied.

Claims

1. A horticultural nutrient product comprising a porous substrate impregnated with an impregnant consisting of or incorporating a nutrient composition dispersed in a water soluble carrier.

2. A product according to claim 1 wherein said substrate comprises a sheet of open-celled foamed plastics material.

3. A product according to claim 2 wherein said substrate comprises polyurethane foam.

4. A product according to claim 3 wherein said substrate comprises polyester-urethane foam.

5. A product according to any preceding claim wherein said substrate is uniformly impregnated over its entire area.

6. A product according to any preceding claim wherein said substrate is impregnated through only part of its thickness.

7. A product according to any preceding claim wherein said impregnant incorporates a fungicide.

8. A product according to any preceding claim wherein said impregnant incorporates a rooting stimulant.

9. Product according to claims 7 and 8 comprising 1-7% rooting stimulant, 3-10% fungicide and the balance nutrient composition.

10. A product according to claim 7 or 9 wherein said fungicide comprises a powder dispersed in said carrier.

11. A product according to claim 8 or 9 wherein said rooting stimulant comprises a powder dispersed in said carrier.

12. A product according to any preceding claim wherein said nutrient composition comprises a powder dispersed in said carrier.

13. A product according to any preceding claim wherein said carrier comprises a water soluble wax.

14. A product according to claim 13 wherein said wax is biodegradable.

15. A product according to claim 13 or 14 where- in said wax comprises a fatty acid ethoxylate.

16. A product according to claim 15 wherein said wax comprises polyethylene glycol monostearate.

17. A product according to any of claims 13 to 16 wherein said wax has a melting point in excess of 45"C.

18. A product according to any preceding claim wherein said impregnant comprises 10-90% by weight of said carrier and 90-10% by weight of nutrient and fungicide/rooting composition if provided.

19. A product according to any preceding claim wherein the ratio of impregnantto substrate is between 2:1 and 10:1 by weight.

20. A product according to any preceding claim which is of annular form having a central hole to receive the trunk or stem of a tree or plant and a generally radially directed slit to enable placing of the product around the plant or tree.

21. A product according to claim 20 wherein said slit is arranged to provide a formation forming a locating tab to facilitate engagement of the two edges of the slot and retention of the product around the plant or tree.

22. A horticultural nutrient product substantially as hereinbefore described with reference to the accompanying drawings.

23. A method of producing a horticultural nutrient product according to any preceding claim comprising introducing said impregnant into said substrate in a melted condition while the substrate is compressed and subsequently allowing the subs trade to expand to draw the impregnant into the structure of the substrate.

24. A method of producing a horticultural nutrient product substantially as hereinbefore described.

25. A horticultural nutrient product produced by the method of claim 23 or 24.

26. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.