WO2004108858A1

WO2004108858A1 - Microbial growth media and soil improvement

Info

Publication number: WO2004108858A1
Application number: PCT/GB2004/002404
Authority: WO
Inventors: Keith Martin Macgregor; Anthony Marston Gibbs
Original assignee: Bio Natura Ltd; Keith Martin Macgregor; Anthony Marston Gibbs
Priority date: 2003-06-06
Filing date: 2004-06-07
Publication date: 2004-12-16
Also published as: GB0313194D0

Abstract

Waste products are pre-treated with a film forming composition comprising a carbohydrate and a chelating compound or complex. The growth of beneficial microbes is thereby stimulated, promoting composting and, ultimately, soil fertility.

Description

MICROBIAL GROWTH MEDIA AND SOIL IMPROVEMENT

FIELD OF THE INVENTION

The present invention relates to compositions able to coat substrates and encourage the development of micro organisms, for example in order to promote soil improvement.

The substrates are not necessarily conducive to their development.

BACK GROUND TO THE INVENTION

Disposal of organic waste material is an ongoing problem and environmental concern. Many natural and man-made organic wastes are difficult to decompose by slow natural mechanisms and composting systems, taking prolonged periods to degrade totally and in some cases the end products are toxic. This is as a result of the development and growth of undesirable micro organisms colonising the waste at the expense of more useful species.

All micro organisms have the ability to create biofilms which act as a safe environment for development and multiplication resulting in healthy microbic colonies. However, some materials appear not to be able to support the development of biofilms and as such are very slow to degrade even though the material could be a source of microbic nutrition. Thus without the protection of a biofilm microbes cannot develop in high enough numbers and in specific species to break down and degrade many waste materials into soil improvement matter.

Cardboard, for example does not support biofilms of sufficient density to create a conducive environment for high microbic activity. The result of this is that cardboard and paper and other wood based products tend to remain un-decomposed for very long time scales. Common methods of dealing with cardboard and similar waste is by land fill or incineration. In the former the waste will remain essentially unaffected for several years and in the latter the calorific value of the material means that it is not a good heat source for further use such as in electricity generation.

Since most commercial and domestic waste is disposed of in land fill sites removing a high percentage of such waste, for example paper and cardboard and other wood based material will essentially reduce land fill costs. By converting such waste by microbic activity will not only reduce land fill costs but offer a commercially useful product for soil improvement.

SUMMARY OF INVENTION

According to the first aspect of the present invention there is provided a composition capable of forming a film comprising the following components:

a source of carbohydrate, preferably in the form of saccharides and or other similar molecular compounds; a chelating compound or complex; preferably derived from fermentation; optionally, a surface active agent; optionally, a source of long chain oligo acids (preferably C6 to C14 average); optionally, a biodegradable polymer; optionally, a source of sulfur; and optionally, a source of nitrogen.

By pre-treating waste, micro organisms can invade, from natural sources, the deposited films, multiply within a safe environment and utilise the waste material as nutrition.

The result of this activity is to decompose the waste into a compost suitable for improving soil fertility by reason of the more easily available elements, from waste and dead and living microbes, suitable for plant nutrition. In addition such degraded material will support a greater spectrum of soil microbes and higher life forms, for example nematodes, all essential for soil fertility The basic structure of the pre-treatment film will provide not only a safe microbic environment but also initially provide, a source of high energy nutrition for the microbes. This is in an easily adsorbed form, which will promote fast and healthy growth leading to rapid invasion of the substrate and thus degradation.

To allow plants to take up minerals from the soil it is often necessary for those minerals such as phosphates to be pre-digested or converted by microbic activity. The resulting form of phosphate is then more easily taken up by the plants. Many natural soils are depleted in the specific micro organisms necessary for bridging the gap between minerals and plants mainly because of alien environments. By creating a suitable film into which microbes can find a safe environment the essential microbes can multiply and thus increase the soil populations and creating a more effective transfer of minerals to plants.

The present invention may, therefore, achieve its various aims in the disposal and conversion of suitable post consumer and other organic wastes. In addition it may encourage the greater release of plant nutrients from inorganic minerals present in the soils.

It may also achieve the removal of suitable organic waste from conventional disposal systems by returning the waste to its source.

In more specific applications of the invention some waste materials such as post consumer cardboard can be converted into a replacement for peat or other scarce natural soil improvement materials.

A SOURCE OF CARBOHYDRATE

Preferably these may be saccharide compounds or other similar complex molecular structures Preferably sources of carbohydrate will be derived from microbial fermentation or other processes but natural sources such as plants will be acceptable. The range of saccharides and other similar complex molecular structures is wide but preferably they will be similar to those secreted by natural micro organisms and include D-glucosyl based biopolymers, for example starch or cellulose, glycerol, D-mannosyl base bio- polymers, hyaluric acid based saccharide biopolymers, for example glycosaminoglycans or monopolysaccharides, alginates carrageenans, pectin, xanthan, glucomannan, xylogoucan, aniylase, cycloamyloses, and O-acetyl substituted and pyruvic acid acetyl substituted polysaccharides. Other saccharides such as soluble carbohydrates, and including glucose, fructose, ribose, sucrose, maltose, lactose, starch and cellulose, may be employed.

Carbohydrates may be used singly or in any combination. They may be in solid form or may be dissolved in a suitable solvent such as polyhydric alcohol, preferably a compound having a 1-3 hydroxyl group. Examples include glycol, propylene glycol, or an alcohol including ethanol or methanol for example. Other solvents including water, non-ionic or anionic surface active agents or methyl sulfonyl methane or long chain oligo acids with C6-C14 chain lengths.

Suitably the source of carbohydrate is present in an amount of at least 0.25% wt, preferably at least 0.3 wt % or more preferably 0.5% wt of the total weight of the composition and most preferably at least 1% wt of the total weight of the composition.

Suitably the source of carbohydrate is present in an amount of no more than 20% wt, preferably no more than 10% wt, more preferably no more than 5% wt and most preferably no more than 3% wt of the total weight of the composition. Thus a suitable range of the amount of carbohydrate in the composition is 0.25% wt to 20% wt of the total weight of the composition, and in especially preferred range is 1-3% wt. In the liquid composition for application to waste the value up to 0.5% wt typically apply. In a dry composition suitable for dispersion the values from 5% wt to 20% wt typically apply. CHELATING COMPOUND OR COMPLEX

The chelate compound or complex is preferably an amino compound or complex. Amino acids are particularly effective metal binding agents and as such may be of primary importance in the transport of minerals within cells or into enzyme systems. Hence the chelate compound or complex preferably comprises an amino acid chelate compound or complex.

Preferably the chelate compound or complex is derived from fermentation.

Suitable chelate compounds include copper chelated ascorbic acid, cobalt chelated ethylene diamine terra acetic acid (EDTA) and iron chelated citric acid.

Especially preferred is copper chelated in ascorbic acid.

Suitably the chelate compound or complex is present in the film forming composition in an amount of at least 0.1% wt preferably at least 0.5% wt and more preferably at least 1% wt of the total weight of the composition. Suitably the amount of the chelate compound or complex present in the film forming composition is no more than 15% wt and preferably no more than 4% wt, more preferably no more than 3.5% wt and most preferably no more than 3% wt of the total weight of the film forming composition. Thus a suitable weight range is 0.1-15% wt of the total weight of the composition and an especially preferred range is 1-3% wt. In a liquid composition for application to waste the values up to 2% wt typically apply. In a dry composition suitable for dispersion onto waste the values from 2% wt up to 15% wt typically apply.

SURFACE ACTIVE AGENT

The critical function of surface activity, when present, is to enhance the spread of the matrix forming film and is best achieved by the inclusion of one or more surface active agents. These are optional depending on the composition of the waste and means of application of the film forming composition.

Suitable agents include but not exclusive nonyl phenol ethoxylates, linear alkyl sulfonates, linear dodecyl benzene sulfonates, alkyl aryl sulfonates, phosphate esters, non ionic alkalolamides and methyl sulfonyl methane. These may be used singly or in suitable ionic combinations.

Other suitable surface active agents are saponification products of polyfunctional esters, plant derived saponins, stearins or plant oils such as coconut oil, rape seed oil, olive oils and sunflower oils.

Preferred surface active agents are non ionic surfactants especially alkyl aryl alkoxylates and anionic surfactants especially alky Is aryl sulfonates.

Surface active agent(s) present are suitably present in an amount of at least 0.01% wt, preferably at least 0.1% wt of the total weight of the composition. Suitably the amount of the surface active agent is no more than 20% wt, preferably no more than 5% wt of the total weight of the composition. Thus a suitable weight range of the surfactant in a film forming composition is 0.1% wt to 20% wt of the total weight of the composition and especially preferred range is 0.1% wt to 5% wt.

ADDITIONAL COMPONENTS

In addition to the core components the composition may comprise additional components specific to the application or substrate. For example, especially where the substrate does not release nitrogen, preferably the film forming composition further comprises a compound capable of release of nitrogen for initial microbic nutrition.

The compound capable of releasing nitrogen for microbial nutrition is preferably urea but other soluble or semi soluble nitrogen releasing compound can be used such as ammonium sulfate Suitably the amount of nitrogen releasing agent present in the film forming composition is at least 0.1% wt, preferably at least 0.5% wt and more preferably at least 1% wt of the total weight of the film forming composition. Suitably the amount of nitrogen releasing compound in the film forming composition is no more than 25% wt, preferably no more than 25% wt of the total weight of the film forming composition. Thus a preferred weight of nitrogen releasing compound present in the film forming composition is between 1% wt and 15% wt of the total weight of the composition.

The film forming composition may further comprise one or more long chain oligo acid complex, preferably carboxylic acids, in the range C6-C14 average. The purpose of these components is to provide a binding agent which act to bind the various components together and to form a basis for the adhesion to surfaces such as cardboard. These may be as an integral part of the total composition or used separately as a first treatment of the substrate onto which the other components are added either singly of as mixtures.

Suitably the amount of oligo acid complex present in the film forming composition is at least 1% wt, preferably at least 5% wt of the total weight of the film forming composition. Suitably the amount of the oligo acid present in the film forming composition is no more than 15% wt, preferably no more than 8% wt of the total weight of the film forming composition. Thus a preferred weight range of the oligo acid complex is between 5% wt and 15% wt of the composition

The film forming composition may further comprise one or more inorganic salts such as sodium thiosulfate, one or more gelling agents such as synthetic laponites, one or more pH balancing agents such as sodium carbonate or citric acid and/or one or more inert fillers such as silicon dioxide or sodium sulfate.

Preferably the composition comprises a source of sulfur, especially thiosulfate salts, for example sodium thiosulfate. Source(s) of sulfur present are suitably present in an amount of at least 0.01% wt, preferably at least 0.05% wt of the total weight of the composition. Suitably the amount of the source of sulfur is no more than 10% wt, preferably no more than 5% wt of the total weight of the composition. Thus a suitable weight range of source(s) of sulfur in a film forming composition is 0.01% wt to 10% wt of the total weight of the composition and an especially preferred range is 0.05% wt to 5% wt.

The film forming composition may further comprise one or more biopolymers based on lactic acid for example lactide isomers comprising L,D or DL lactides or lactide/glycolide. The purpose of these (co) polymers is to provide viscosity to liquid formulations or to provide adhesion and spreading properties to powder and liquid compositions. They provide strength and stiffness to polymer matrices in the composition, and are fully biodegradable thus contributing to microbic nutrition

Suitably the amount of lactide isomers present in film forming composition is at least 0.005% wt of total weight of the film forming composition nor greater than 2% wt. Thus a preferred range of the isomers will be between 0.01% wt and 2.5% wt of the total weight of the film forming composition.

The composition may also comprise additional components such as colour, fragrances or other application-specific components at any time be deemed appropriate.

The balance of the composition typically comprises deionised water or solid bulking agent as appropriate to the application for which it will be used.

The film forming composition may be in the form of a liquid or powder, especially a granular powder which may be dissolved in a solvent or used directly in conjunction with an adhesive agent such as oligo acids or lactide isomers. Solvents may be in the form of water, preferably deionised or an alcohol or other organic solvent.

The film forming composition may be in the form of an emulsion or as a molten solid. Alternatively the film forming composition may comprise a suspension or dispersion of a solid composition in a suitable liquid, preferably an aqueous liquid or more preferably deionised water.

MULTIPLE COMPONENTS

The above definitions of the amounts of the carbohydrates, chelates, surface active agents, surfactants, sources of nitrogen and sources of sulfur are summated amounts, when there is a plurality of any such compounds. For example when there are two surface active agents they preferably together supply no more than 20% wt of the composition.

One compound may serve two functions, from those mentioned above. For example one compound could be a chelating complex and a source of nitrogen. In such cases the composition still falls within the present invention provided that definitions which apply to each such function are satisfied.

According to the second aspect of the present invention there is provided a microbial protection medium comprising a solid carrier on which is coated a film of the film forming composition of the first aspect of this invention.

The film forming composition effects a protective environment for subsequent microbial colonisation. The essential ingredients provided by a saccharide compound or complex and the amino chelate compound or complex encourage microbial growth and subsequent penetration and/or digestion of the solid carrier by the microbes.

Suitably the carrier comprises a solid organic (natural) material. Suitable organic materials include paper, cardboard, hemp, miscanthus, straw, wood chippings, bark or other plant derived materials, plant waste, animal waste, synthetic organic waste such as elastomers (including chipped tyres), polymers, animal derivatives, to include fur, feathers and other body parts. Other carrier materials can comprise inorganic inert materials such as sand, crushed rocks and other minerals in suitable form, inorganic surfaces such as concrete, and natural or synthetic stone.

Preferred carriers are paper, cardboard, straw, wood chips, sand and natural soils and earth.

According to the third aspect of the present invention there is provided a method of manufacturing a microbial medium of the second aspect of the invention comprising the steps of:-

(a) providing a film forming composition of the first aspect of the invention.

(b) providing a solid carrier

(c) coating the solid carrier with a film forming composition such that the film forming composition forms a film on the surface of the carrier.

For example, the film forming composition may be coated onto an inorganic carrier in areas where contamination by agents, which are degradable by microbes, has occurred. The film forming composition may be coated onto flooring, natural or synthetic rock or stone, sand or gravel or other areas likely to be contaminated with oil or other degradable organic deposits.

If the film forming composition is a liquid composition step (c) above may comprise coating the carrier with a liquid by any suitable method such as spraying, or dipping for example. If the film forming composition is a solution, dispersion or suspension of a solid composition in a suitable liquid the method may comprise after step (c), removing the liquid by any suitable method such as evaporation of the liquid by air drying, for example.

If the film forming composition is in the form of a powder or granules, step (c) may comprise adsorbing the composition directly onto a carrier or depositing a film of the powder or granules directly onto the carrier. Alternatively the carrier may be pre- coated with an adhesive such as an oligo acid or biodegradable polymer followed by dispersion of the powder or granules onto the carrier. Alternatively if the film forming composition is in the form of a soluble powder or granules step (c) may involve dissolving the composition into a suitable solvent and coating the carrier with the resulting solution by any suitable means such as spraying or dipping for example.

The method may further comprise at least partially drying the coated carrier. Preferably the method comprises fully drying the coated carrier to effect a solid film of the film forming composition on the surface of the carrier. The method may comprise wetting the coated carrier after drying.

Suitably the carrier is as described for the second aspect of the invention. Suitably the film forming composition is coated onto the carrier to provide a coating weight of at least 2 grams per square metre and not more than 100 grams per square metre. Thus a preferred weight range of film forming composition is between 30 grams and 100 grams per square metre

Where the carrier is granular or particulate or powder then the preferred weight range of the film forming composition will be at least 10 grams per kilogram and not more than 50 grams per kilogram, thus a preferred weight range of the film forming composition is between 15 grams and 40 grams per kilogram of powder, particulate or granules.

Alternatively where the film forming composition is applied to natural soils sand or clays the preferred weight range of film forming composition will be at least 250 grams per square metre, thus a preferred weight range of the film forming composition is between 300 grams and 800 grams of the film forming composition per square metre

The desired quantities can be applied directly to the soil or more preferably by pre diluting or dissolving in a suitable liquid, preferably aqueous not more than one part of film forming composition and 9 parts water of solvent. According to a fourth aspect of the present invention there is provided a method of stimulating microbial activity at a locus comprising the step of:-

(a) applying the microbial protection medium of the second aspect of the invention to the locus.

In this instance the microbial protection medium would serve to encourage microbial activity at the locus where acceleration of the degrading process is required. Suitably areas including soils, sand, soiled animal bedding, animal waste, plant waste and domestic organic waste be treated. Equally the locus may be an inorganic surface such as a floor or other natural or synthetic build material or structure.

Suitably step (a) comprises a layer of the microbial protection medium to the locus, for example to land or other surfaces which are contaminated with a microbially. degradable contaminant such as oil for example. Equally a carrier, for example wood dust, or chippings coated with the film forming composition of the invention may be spread over the locus to achieve the same purpose.

The method may also comprise a step of wetting the locus before or after the application of the layer of microbial protection film.

EXAMPLES

The following examples are more particularly seen to illustrate the various aspects of the present invention and should not be considered as limited to these illustrations.

The following materials, and their suppliers, are referred to hereinafter:-

Saccharides - ADM Ingredients, Erith, Kent, UK. Typically derived from fermentation or plant derived sources;

Glycerol - Croda Chemicals Ltd, Goole, UK; Cellulose - Arthur Brownwell, London UK;

Amino chelate complexes, typically metals chelated with citric acid and cobalt chelated with ethylene diaminetetra acetic acid - Albion Laboratories Inc, Clearfield, Utah, U.S.A;

Copper chelated in ascorbic acid - CROPPER (™) from Albion Labs., USA;

Surface active agents - Nonyl phenol ethoxylates of 9 MW. Typically Synperonic N or Caflon TS such as obtained from ICI Ltd; Linear dodecyl benzene sulfonate such as obtained from Cargo Fleet Chemical Co, Ltd; or in dry powder form Empicol LM such as obtained from Albright & Wilson UK;

Long chain (C6-C14) carboxylic acid blend typically obtained and known as Stream 2 from Global Commodities Ltd, Shipdham, Norfolk;

Nitrogen release agents, typically in the form of urea and ammonium sulfate such as obtained from Fisons Ltd.

EXAMPLE ONE

PART ONE:

A film forming composition suitable for treating a solid carrier for use as a soil improving agent either as a surface mulch or used in a subsurface application shown below. FORMULATION A.

Saccharide 1% w/v Amino chelate complex 1 % w/v

S odium thio sulfate 0.1% w/v

Urea 2.5% w/v

Brown or black dye as required,....Kenazol paper brown B-FN

PART TWO

Oligo acid complex 95.4%w/v

PREPARING COMPOSITION

Mix all the powder components shown in PART ONE thoroughly.

Dissolve with heat the oligo acid complex 1 : 1 with deionised water.

The final pH of the composition was determined as between 5.5 and 7.5

APPLICATION TO CARRIER MATERIAL

PART TWO of formulation A was sprayed directly onto the carrier, typically chipped cardboard at the rate of 50 litres per tonne of cardboard in a suitable tumble mixer.

PART ONE of the formulation was then dispersed onto the treated cardboard at the rate of 5 kg per tonne of cardboard again in a suitable tumble mixer.

When the second treatment was completed the cardboard chips were tumble mixed for a further 15 minutes to ensure cardboard chips received a homogenous coating of film forming composition. This final mixing can be accompanied by dry air or by low heat to establish a firm adhesion of the film forming composition to the cardboard chips.

TYPICAL APPLICATIONS

As a Subsurface Additive

The treated cardboard was then used in a number of soil improvement and/or horticultural applications. For example it was used as a layer of approx 20mm thick on prepared ground prior to laying turf. Cardboard chips should be slightly wetted before turves are laid.

A further example used treated cardboard chips as a lining for holes in preparation for planting shrubs or small trees. To improve structure of the treated cardboard when lining holes it is preferably wetted and used as a layer of at least 60mm thick at the bottom of the hole and up to 20 mm for lining the sides. Alternatively the chipped cardboard can be added to the back fill soil but ensuring that there is at least 60 mm at the bottom

The primary function of this application is to provide controlled moisture release to the newly planted shrub or tree. This will reduce stress on the plant. In addition the chipped cardboard will entrap air at the critical root soil interface thus reducing compaction. This is a mechanical function of the platelet structure of the chips.

Over a short time scale it was found that the soil microbic levels around the plant increased substantially thus indicating a state of enhanced soil fertility.

As a Surface Mulch

Chipped cardboard treated with formulation A above was used as a surface mulch. The main advantages are:- 1. As a replacement for scarce peat and other plant derived materials

2. Unlike compost or other mulch materials it consists of a single source of organic matter thus reducing any introduced disease of plants

3. It has unique moisture holding capacity 4. Holds moisture and thus reducing drying out under high ambient temperatures.

5. High insulation, reduces loss of heat and also reduces frost penetration.

6. Very high bioactivity at soil / mulch interface including nematodes and other invertebrates

7. Can be pH controlled to suit plant needs 8. Can be colour coordinated for architectural effects

9. Reduces weed growth

10. Reduced wind dispersion platelets stick together

11. Low oxidation rate many mulches oxidise and lose beneficial effects

For best results a mulch thickness of at least 40mm is needed depending on needs.

EXAMPLE TWO

FORMULATION B

A film forming composition suitable for direct inclusion to garden and other compostable waste materials including single source compostable waste ie chipped cardboard, wood chips and other suitably structured organic material. The purpose of this formulation is to enhance biological activity by providing a safe environment and a high initial nutrition source for a wide spectrum of essential microbes.

Saccharide 20% w/v

Amino chelate complex 3% w/v

Sodium thiosulfate 0.1% w/v Urea 4% w/v

Wood flour to 100% w/v The above components were mixed in order shown and packed in an airtight container

APPLICATION

Formulation B was added as a starter concentrate powder to normal garden and domestic compostable waste at the rate of 500gms per 0.1 cubic metres and mixed in well. Subsequent applications were used at the rate of lOOgms per 0,1 cubic metres of new waste materials.

Waste was stored in a 1 metre cube container with adequate air circulation and drainage. At the end of the autumn when container was full a 100mm layer of mulch (example one above) was placed on the surface. The object of this was to prevent heat escape during cool weather.

It was found that normal garden and domestic waste was degraded rapidly and at least 3-5 times as fast as under no treatment conditions. Woody materials degraded equally as rapidly. Even with the inclusion of animal waste there was no odour.

EXAMPLE 3

A film-forming composition suitable for treating a solid carrier for use as a soil improving agent was formed by mixing the following ingredients.

Polysaccharide, in the form of starch 1% w/w Copper chelated in ascorbic acid 1 % w/w

Surfactant in the form of nonyl phenol ethoxylate 0.2% w/w

Sodium thiosulfate, commercial grade 0.1% w/w

Urea, commercial grade 2.5% w/w

Deionised water to 100% w/w

The above formulation was found to be effective in meeting objectives of the present invention. The reader's attention is drawn to all papers and documents which are filed concunently with or previous to this specification in connection with this application and which are open to public inspection with this specification and its contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawing) and/or all of the steps of any method of process so disclosed may be combined in any combination except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same equivalent or similar purpose unless expressly stated otherwise. Thus unless expressly stated otherwise each feature disclosed is one example only of a generic series of equivalent or similar features.^'

The invention is not restricted to the details of the foregoing embodiments (s). The invention extends to any novel one or any novel combination of the features disclosed in this specification (including any accompanying claims abstract or drawings) or any novel combination of the steps of any method or process so disclosed.

Claims

1. A composition capable of forming a film comprising the following components:

a source of carbohydrate; a chelating compound or complex; optionally, a surface active agent; optionally, a source of long chain oligo acids; optionally, a biodegradable polymer; optionally, a source of nitrogen; and optionally, a source of sulfur.

2. A composition a claimed in claim 1, wherein the carbohydrate is derived from a plant source, or from microbial fermentation.

3. A composition as claimed in claim 1, wherein the carbohydrate is a polysaccharide biopolymer.

4. A composition as claimed in claim 1, wherein the carbohydrate is selected from D-glucosyl based biopolymers, for example starch or cellulose, glycerol, D-mannosyl base bio-polymers, hyaluric acid based saccharide biopolymers, for example glycosaminoglycans or monopolysaccharides, alginates canageenans, pectin, xanthan, glucomannan, xylogoucan, amylase, cycloamyloses, and O-acetyl substituted and pyruvic acid acetyl substituted polysaccharides, soluble carbohydrates, glucose, fructose, ribose, sucrose, maltose, lactose, starch and cellulose.

5. A composition as claimed in any preceding claim, wherein the carbohydrate is present in the composition in an amount of from 0.25% wt up to 20% wt.

6. A composition as claimed in any preceding claim, wherein the chelate compound or complex is an amino compound or complex or a copper chelate complex.

7. A composition as claimed in any preceding claim, wherein the chelate compound or complex is present in an amount of from 0.1% wt up to 15% wt.

8. A composition as claimed in any preceding claim, wherein the composition contains a surface active agent, namely of from 0.01% wt up to 20% wt of an anionic, non-ionic, amphoteric or cationic surface active agent.

9. A composition as claimed in any preceding claim, wherein the composition contains a source of long chain oligo acids, namely of from 1% wt up to 15% wt thereof.

10. A microbial protection medium comprising a solid carrier on which is coated a film or a composition as claimed in any preceding claim.

11. A medium as claimed in claim 10, wherein the solid carried is a natural organic material, or an inorganic inert material, or a polymeric or elastomeric material.

12. A method of manufacturing a microbial medium as claimed in claim 10 or 11 comprising the steps of:-

(d) providing a film forming composition of the first aspect of the invention.

(e) providing a solid carrier

(f) coating the solid carrier with a film forming composition such that the film forming composition forms a film on the surface of the carrier.

13. A method of stimulating microbial activity at a locus comprising the step of:-

(a) applying the microbial protection medium of claim 10 or 11 to the locus.