GB2129785A

GB2129785A - Plant growing media

Info

Publication number: GB2129785A
Application number: GB08224123A
Authority: GB
Inventors: Allan Cooke
Original assignee: Chemical Discoveries SA
Current assignee: Chemical Discoveries SA
Priority date: 1982-08-21
Filing date: 1982-08-21
Publication date: 1984-05-23
Also published as: GB2129785B

Abstract

A growing medium comprises a mass of particulate growing material and a minor proportion of a synthetic polymeric substance which can absorb a volume of water greater than its own volume such that said absorbed water is freely available for transfer to a plant growing in the medium, said medium incorporating a water soluble plant nutrient mix derived from seaweed and digested organic waste. The polymeric substance may comprise a cross-linked acrylamide.

Description

SPECIFICATION Plant growing media This invention relates to growing media for plants.

Our copending Application No. 8219676 describes a method of producing a growing medium (hereinafter referred to as the method defined) wherein a mass of particulate growing material is mixed with a minor proportion of a synthetic polymeric substance which has the property of absorbing a volume of water appreciably greater than its own volume in a state in which said absorbed water is freely available for transfer from the polymeric substance to the root system of a plant growing in the medium.

The growing medium resulting from the performance of this method has beneficial plant growth properties particularly with regard to water retention and physical structure and such method is therefore of particular application in the improvement of the properties of poor soils (such as dry, sandy soils) and also in the production of artificial growing media (for example for pot growth of plants).

The principal object of the present invention is to extend said method such asto supplement the beneficial plant growth properties of the resulting growing medium.

According to the invention therefore the method defined is supplemented by the step of incorporation in said growing medium of a water-soluble plant nutrient mix derived from seaweed and also digested organic waste.

With this procedure it will be appreciated that a growing medium can be obtained which not only has good water retention and structural properties but also is capable of providing all, or at least a major part, of the nutrients required for healthy plant growth, it being understood that the said plant nutrient mix is suited to the supply of both essential trace elements (from the seaweed) and major soil fertilizing components (from the organic waste).

Moreover, in so far as the nutrient mix is present in aqueous solution absorbed by the polymeric substance it will be appreciated that this facilitates retention of such mix evenly distributed throughout the growing medium in a condition in which it is readily available for use by plants growing in the medium.

With regard to the organic waste used for nutrient purposes in the method of the invention this is preferably anaerobically digested and cattle slurry is especially advantageous since this is high in nitrogen phosphorous and potassium, major nutrient ingredients normally lacking in seaweed.

With regard to the seaweed this may be of any suitable kind and may be processed to a watersoluble form in any suitable manner, for example, by heating dried seaweed "meal" with water in a pressure vessel (say up to 100ppsi (7 x 105 Pa) and up to 200"F (93"C) for six or seven hours) followed by removal of residual fibrous and other solid matter.

Most preferably the seaweed and organic waste processing steps are combined by utilising the aqueous component of the digested organic waste (after separation from residual solid matter) as the aqueous medium with which the seaweed is heated under pressure to liquefy same.

The digestion of the organic waste is preferably effected so as to liberate methane gas, for example by storing the organic waste in a sealed vessel at about body temperature (98"F, 37"C) for a period of time (say seven to ten days) sufficient to allow gas to be produced by fermentation. This anaerobic digestion process advantageously provides utilisable methane and also has a deodorizing action.

With regard to the synthetic polymeric substance utilised in the method of the invention this may be any suitable compound or mixture of compounds although preferably it is an anionic polymer, especially an acrylamide polymer, for example an acrylamide polymer cross-linked with methylene bisacrylamide which comprises particles or granules having the property of absorbing up to say 30 or 35 times its own volume of water by swelling of the particles to form moist sticky gel-like beads, as described in copending Application 8219676.

In one embodiment the aqueous seaweed/organic waste liquid is mixed with the polymeric substance in proportions (say one part polymer to 50 to 100 parts by volume nutrient liquid) suited to the production of a fluent, pumpable material which can be sprayed or similarly applied over the surface of the particulate growing material to be mixed therewith (e.g. a ground area of sandy soil). Alternatively, the polymeric substance and liquid seaweed/organic waste nutrient may be mixed with each other and with any suitable naturally occurring or specially provided particulate growing material in any other suitable manner.In this respect reference is made to the aforementioned copending Application which describes various kinds of particulate growing material (including soil, sand, rockwool, peat), various modes of admixture of water-absorbent polymeric substance with such growing materials, and various contexts of use of the resulting mixtures; and these features may be applied to the present invention as appropriate.

As mentioned, in use, the growing medium deriving from the method of the present invention advantageously involves absorption of the aqueous nutrient mixture by the polymeric substance. It is however to be understood that prior to use the nutrient mixture may be dry (especially in the form of a dehydrated powder) since this can be more convenient and economical to store and transport.

Thus, for example, the polymeric substance and the nutrient mixture, and possibly also at least part of the particulate growing material (especially where a specially provided material such as rockwool or sand is used), may be mixed in total (or partial) dry form, water being added for reconstitution purposes at a later stage (prior to, or even after, transfer of the mixture to the location of use, e.g. the land area to be provided with improved growing properties).

If desired, other supplementary substances may be incorporated for example binding materials and the like, as described in the aforementioned copending Application.

Claims

CLAIMS (Filed on 22/8/83)

1. A method of producing a growing medium wherein a mass of particulate growing material is mixed with a minor proportion of a synthetic polymeric substance which has the property of absorbing a volume of water appreciably greater than its own volume in a state in which said absorbed water is freely available for transfer from the polymeric substance to the next system of a plant growing in the medium, said medium incorporating a water solubie plant nutrient mix derived from seaweed and digested organic waste.

2. A method as claimed in claim 1, wherein the said mix comprises an aqueous solution absorbed by the polymeric substance.

3. A method as claimed in claim 1 or 2, wherein the organic waste has been anaerobically digested.

4. A method as claimed in claim 3, wherein the organic waste comprises anaerobically digested cattle slurry.

5. A method as claimed in any preceding claim, wherein the seaweed is heated with water under pressure.

6. A method as claimed in claim 5, wherein the seaweed is heated under pressure with digested organic waste.

7. A method as claimed in any preceding claim, wherein the organic waste is digested so as to liberate methane.

8. A method as claimed in any preceding claim, wherein the polymeric substance comprises an anionic polymer.

9. A method as claimed in claim 8, wherein the polymer comprises an acrylamide polymer.

10. A method as claimed in claim 9, wherein the acrylamide polymer is cross-linked with methylene bisacrylamide.

11. A method as claimed in any preceding claim, wherein the particulate growing material is selected from: soil, sand, rockwood or peat.

12. A method as claimed in claim 1 substantially as hereinbefore disclosed.