Composition

INTRODUCTION

The present invention relates to a film-forming mulch composition comprising non-chemically modified potato peel and/or an extract therefrom, a plasticiser and water. The invention also relates to a container containing the composition, to a kit for preparing the composition and to a method for preparing the composition. Additionally the invention relates to a mulch film comprising the composition and to methods of making mulch film as well as to methods of controlling weed growth using the mulch film.

BACKGROUND

Mulch films are applied to soil to inhibit weed growth, maintain soil temperature and improve soil moisture. For example a mulch film may be placed over soil so that weed seeds present in the soil are deprived of light and germination is inhibited. Naturally the film should allow water and air to pass there through to promote growth of the desired crop. The overall effect of the use of mulch film is to significantly improve the growing environment for agricultural plants thereby improving their yield.

Conventional mulch films are primarily made from low density polyethylene (LDPE) which has the advantages of being able to transmit long wave radiation as well as good mechanical properties which facilitate both the layout and eventual removal of the films from the soil. The steps of layout and removal are, however, time consuming and costly, even when machinery is employed. Moreover LDPE mulch films are a significant contributor to plastic waste which must be sent to landfill.

To overcome some of the limitations associated with the use of LDPE mulch films, there has been a trend towards the development of degradable mulch films. This has been driven by changes in the regulatory framework requiring the use of biodegradable and bio-based mulch films due to the need to reduce plastic waste for environmental reasons. The idea of degradable mulch films is that whilst they have the necessary mechanical properties to inhibit weed growth, they will eventually degrade and obviate the need to remove them from the soil surface after use.

A number of different types of degradable mulch films have been developed employing a wide range of different biopolymers. Examples include mulch films based on starch, cellulose, chitin, chitosan, alginic acid, polypeptides, polyesters, polyamides, polyacrylates and polyurethanes. Other mulch films have been developed that are based on natural renewable sources such as corn starch, lignocellulosic fibre waste, hemp with sodium alginate and by products of the paper-textile industry. A number of these are available commercially. Generally they are more expensive than conventional LDPE mulch films which may be the reason that their use has been limited.

More recently there has been a drive to provide mulch films that are sprayable, i.e. mulch films that can be applied as a water-based liquid, which after application, dries to form a film on the soil surface. The clear advantage of sprayable mulch films is that they are much cheaper and easier to apply than pre-cast films. A number of different materials have been developed for use as sprayable mulch films including polysaccharides, proteins, polyethylene glycols and polysiloxanes. Most attention has probably been focussed on polysaccharides as they are biodegradable, biocompatible, non-toxic and available from renewable resources.

WO201 1/128752 discloses a sprayable composition that forms a mulch film. The composition comprises an aqueous, hydroalcoholic or acidulated water base, at least one polysaccharide of natural origin with beta-1 ,4-glucan structure selected from the group consisting of alginic acid, carrageenan, chitosan, hydroxyethylcellulose and a derivative thereof, a mixure of plant fibers or particles and a plasticiser. The mixture of plant fibers or particles is said to regulate the mechanical resistance and duration of the film and preferably comprises short natural fibers, having a longitudinal dimension of less than 5 mm and a section less than 0.5 mm, of cellulosic nature. The plant fibers or particles therefore act as fillers. The examples recited in WO201 1/128752 include tomato skins and seeds, marc, olive oil pressing residue, citrus fruit peel and pips, waste from wheat, corn, rice, and algae.

The challenge with polysaccharides, however, is their low water resistance and relatively poor mechanical properties. Different strategies have been adopted to address these limitations of polysaccharides. There are reports, for example, of mixing polysaccharides with gums to improve water resistance and mixing polysaccharides with cellulose fibres, wheat fibres and/or powdered seaweeds to increase the film tensile strength after drying.

A different approach that has been adopted is to modify the polysaccharide itself. There are numerous reports, for instance, of chemically modifying starch to modify its properties. Examples of the types of modification that are carried out include oxidation and derivatisation, e.g. acetylation.

US 7,805,883, for example, describes a soil cover comprising potato steam peels or a part thereof and in particular the cork fraction. US 7,805,883 teaches that preferably the potato steam peels or the cork fraction thereof undergo a chemical modification to reduce the carbohydrates/starch available to reduce fungus formation on the final mulch film. The chemical modification advocated is oxidation, but other examples of chemical modifications mentioned are substitution, hydrophobing, acetylation and cross linking. US 7,805,883 concludes in its results section that the soil cover layers made of oxidised peels remain moist the longest and exhibit least shrinkage, and acetylated peels may also be useful to reduce drying rate.

Another important factor to consider is the overall cost of producing sprayable biodegradable mulch films. The cost of production of biodegradable films is generally 2- 3 times higher than, e.g. LDPE films. This is particularly the case when the biopolymer undergoes chemical modification prior to use since this introduces extra steps into its production.

SUMMARY OF THE INVENTION

Viewed from a first aspect the present invention provides a film-forming mulch composition comprising:

(i) non-chemically modified potato peel and/or an extract therefrom;

(ii) a plasticiser; and

(iii) water.

Viewed from a further aspect the present invention provides a container containing a film-forming mulch composition as hereinbefore defined.

Viewed from a further aspect the present invention provides a kit for the preparation of a film-forming mulch composition as hereinbefore defined comprising:

(i) a first container comprising a non-chemically modified potato peel and/or an extract therefrom and a plasticiser; and

(ii) instructions for preparing said composition.

Viewed from a further aspect the present invention provides a method for preparing a film-forming mulch composition as hereinbefore defined comprising:

(i) dispersing non-chemically modified potato peel and/or an extract therefrom and a plasticiser in water; and

(ii) mixing the non-chemically modified potato peel and/or an extract therefrom, plasticiser and water.

Viewed from a further aspect the present invention provides a mulch film comprising:

(i) non-chemically modified potato peel and/or an extract therefrom;

(ii) a plasticiser; and (iii) optionally water.

Viewed from a further aspect the present invention provides a mulch film obtainable by:

(i) spraying a composition as hereinbefore defined; and

(ii) evaporating said water thereby forming a film.

Viewed from a further aspect the present invention provides the use of a film forming mulch composition as hereinbefore defined to prepare a mulch film.

Viewed from a further aspect the present invention provides a method of preparing a mulch film comprising:

(i) spraying a composition as hereinbefore defined; and

(ii) evaporating said water thereby forming a film.

Viewed from a further aspect the present invention provides a method of controlling weeds comprising:

(i) spraying a composition as hereinbefore defined onto soil; and

(ii) evaporating said water thereby forming a film over the soil.

Viewed from a further aspect the present invention provides a method of preparing a mulch film comprising:

(i) casting a composition as hereinbefore defined on a cast film line.

Viewed from a further aspect the present invention provides a method of controlling weed growth comprising laying a pre-cast film as hereinbefore defined onto soil and fixing said film in place.

DEFINITIONS

As used herein the term“mulch” refers to a covering which is applied to the surface of soil to, e.g. control weed growth, retain moisture and/or enrich the soil. The term“mulch composition” refers to a composition used to form a mulch.

As used herein the term“mulch film” refers to a unitary layer formed over soil which is continuous, as opposed to existing in a number of pieces.

As used herein the term“film-forming” refers to composition which, when applied, e.g. by spraying, to the surface of soil, forms a film thereon due to the evaporation of water.

As used herein the term“non-chemically modified potato” peel refers to potato peel which is not chemically modified following its removal from its potato and prior to its incorporation into the film-forming mulch composition. Thus, for example, the peel is not derivatised (e.g. acetylated) or oxidised. As used herein the term“vegetable” refers to a plant or part of a plant that is used as food. The parts of a plant that may be used as food includes its fruit, seeds, roots, tubers, bulbs, stems, leaves or flowers.

As used herein the term“fruit” refers to a part of a plant that is the matured ovary of a flower that has seeds.

As used herein the term“particles” refers to a mixture of particles, each particle being approximately spherical in shape. Preferred particles are powder particles.

As used herein the term“powder” refers to dry, free-flowing powder. Typically the particles that constitute the powder have an average diameter of 250-600 mhi.

As used herein the term“plasticiser” refers to a substance which is added to film forming compositions to improve the flexibility of the final film.

As used herein the term water-soluble polymer refers to a polymer which has a solubility in water of at least 20 g per 100 ml of water.

As used herein the term “colourant” refers to pigments, dyes and mixtures thereof.

As used herein the term sprayable refers to a liquid that can be moved through the air in the form of droplets, typically by dispersion from a nozzle.

As used herein the term viscosity refers to the viscosity of a liquid as measured by Viscotester VT 01/02, Gebryder Haake, Berlin, Germany. Typically the viscosity is measured at 40 °C and immediately before spraying by dipping the viscometer rotor into the liquid.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a film-forming mulch composition. The components are:

(i) non-chemically modified potato peel and/or an extract therefrom;

(ii) a plasticiser; and

(iii) water.

Preferably the composition further comprises (iv) water-soluble polymer; (v) cross-linking agent and (vi) filler.

The film-forming mulch composition of the present invention is a sprayable composition that, on application to soil, dries to form a film. The film is often referred to as a mulch film or as a soil cover or layer.

Advantageously the film-forming mulch composition of the present invention comprises inexpensive waste-product (i.e. potato peel) from the food industry and is easy and cheap to apply. As a result the film-forming mulch compositions of the invention are relatively inexpensive per unit area of field compared, for example, to biodegradable mulch films commercially available on the market today. Despite their low cost, the film forming mulch compositions of the invention are highly biodegradable and sustainable and satisfy the key requirement of a mulch film, namely supressing weed growth.

Non-chemically modified potato peel and/or an extract therefrom

The film-forming mulch compositions of the present invention comprise non- chemically modified potato peel and/or an extract therefrom.

Preferably the film-forming mulch compositions of the present invention comprise non-chemically modified potato peel. Thus the potato peel present in the film-forming mulch compositions of the present invention is preferably not chemically modified after its exit from potato processing and prior to incorporation into the composition. This keeps the cost of the potato peel low. Particularly preferably the potato peel is not oxidised prior to incorporation into the film-forming mulch composition of the present invention. Particularly preferably the potato peel is not acetylated prior to incorporation into the film forming mulch composition of the present invention. Particularly preferably the potato peel is not cross-linked prior to incorporation into the film-forming mulch composition of the present invention. Particularly preferably the potato peel is not derivatised prior to incorporation into the film-forming mulch composition of the present invention. Still more preferably the potato peel is not oxidised, acetylated, cross-linked or derivatised prior to incorporation into the film-forming mulch composition of the present invention.

Preferably the potato peel present in the film forming mulch composition of the present invention is obtained as a by-product from the potato processing industry. Particularly preferably the potato peel is from steamed peeled potatoes or abrasive peeled potatoes. In the potato processing industry, the potatoes are sometimes washed and then treated with steam under pressure so that the skin detaches from the remaining potato thereby enabling the skin to subsequently be removed by brushing. The peel preferably incorporated into the present invention may be the product removed in this step. Alternatively the potato peel may be the product obtained from an abrasive potato peeling unit.

In preferred film-forming mulch films of the present invention the entirety of the potato peel is incorporated into the composition. Thus preferably the potato peel is not divided into different fractions (e.g. carbohydrate, protein and cork) prior to incorporation into the film-forming mulch compositions of the present invention. Optionally the potato peel is dried or partially dried. Preferably drying is the sole processing carried out on the peel received as waste from potato processing. If drying is not carried out then preferably the potato peel is not processed to alter its natural composition, i.e. it is used raw. Preferably therefore at least 95 %wt and more preferably 95-100 %wt, and still more preferably 97-100 %wt of the potato peel received as waste from potato processing is incorporated into the compositions of the invention.

In preferred film-forming mulch compositions of the present invention the potato peel is dried prior to incorporation into the film-forming compositions of the present invention. Preferably the water content of the dried potato peel is 0.5-10 %, more preferably 1 -7.5 % and still more preferably 2-6 %. Drying may be carried out by any conventional procedure known in the art, e.g. in an oven. Typical drying conditions might be, for example, 35-70 °C for 24-72 hours.

Preferably the dried potato peel is milled and/or ground. The process of milling and/or grinding reduces the size of the potato peel and generates a more homogeneous mixture of peel in the form of substantially spherical particles. Milling and/or grinding may be carried out by conventional processes known in the art. Thus in preferred film forming mulch compositions of the present invention the potato peel is in the form of particles and still more preferably in the form of powder. The provision of potato peel in the form of particles or a powder advantageously improves the gelatinisation of the potato peel during preparation of the film-forming mulch compositions. Preferably the homogeneity of the gel is improved. In preferred compositions of the invention, the potato peel forms a gel in water.

Particularly preferably the potato peel particles have an average diameter of 250- 600 mhi and more preferably 300-500 mhi. Still more preferably the potato peel particles have a d of 100-400 mhi and more preferably 200-300 mhi. Still more preferably the potato peel particles have a do g of 400-700 mhi and more preferably 500-600 mhi. The provision of potato peel in the form of homogeneous particles advantageously improves the consistency of the performance of the resulting film. For example it improves the uniformity of the thickness and tensile properties of the mulch film eventually formed.

Alternatively or additionally the film-forming mulch compositions of the present invention comprise an extract from potato peel. Preferably the extract is a non- chemically modified extract. Preferably the extract is a powder obtainable by (e.g. obtained by): (i) centrifuging waste water produced from the potato peeling process to yield a starch-rich extract and (ii) drying said starch-rich extract. Preferably the extract is dried potato starch obtainable by (e.g. obtained by): (i) centrifuging waste water from potato peeling to yield a starch-rich extract and (ii) drying said starch-rich extract.

Some preferred film-forming mulch compositions of the present invention comprise non-chemically modified potato peel and a non-chemically modified extract therefrom.

The amount of non-chemically modified potato peel and/or extract therefrom present in the film-forming mulch compositions of the present invention is preferably SO SO %wt, more preferably 40-85 %wt and still more preferably 50-80 %wt, based on the total weight of the dry ingredients. The non-chemically modified potato peel and/or extract therefrom is a film-forming component of the composition of the invention. Preferably the concentration of the potato peel, or the non-chemically modified extract therefrom, in the film-forming mulch composition is 15-150 g per litre, more preferably 20-130 g per litre and still more preferably 40-90 g per litre.

Plasticiser

The film-forming mulch composition of the present invention also comprises a plasticiser. The purpose of the plasticiser is to improve the flexibility of the mulch film, once formed. This means that the film is less prone to tear if, e.g. the film is blown in the wind, or the soil is moved.

Preferred plasticisers present in the film-forming mulch compositions of the present invention are biodegradable and safe, i.e. non-toxic to the environment. Representative examples of suitable plasticisers include sorbitol, maltitol, xylitol, mannitol, erythritol, glycerol, glycerol trioleate, citric acid, tributyl citrate, acetyl tri-ethyl citrate, glyceryl triacetate, polyethylene oxide, polypropylene oxide, ethylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, urea and mixtures thereof. Particularly preferably the plasticiser is glycerol. Film-forming mulch compositions of the invention comprising glycerol have been found to form particularly flexible and non-brittle films.

In preferred film-forming mulch compositions of the present invention the weight ratio of the potato peel and/or an extract therefrom to the plasticiser is 90:10 to 50:50, more preferably 80:20 to 60:40 and still more preferably 75:25 to 65:35. It has been found that at these ratios flexible films are formed which are effective at suppressing weed growth.

The amount of plasticiser present in the film-forming mulch compositions of the present invention is preferably 5-50 %wt, more preferably 10-40 %wt and still more preferably 15-30 %wt, based on the total weight of the dry ingredients. Preferably the concentration of the plasticiser in the film-forming mulch composition is 5 to 50 g per litre, more preferably 7.5 to 40 g per litre and still more preferably 10-25 g per litre.

Water

The water present in the film-forming mulch compositions of the present invention is preferably deionised water. Preferably the water is not acidic. Preferably the water is not hydroalcoholic.

The amount of water present in the film-forming mulch composition of the present invention is preferably 60-98 %wt, more preferably 70-95 %wt and still more preferably 80-95 %wt, based on the total weight of the composition.

Water-soluble polymer

The film-forming mulch composition of the present invention preferably further comprises a water-soluble polymer. Preferably the water-soluble polymer is a film forming polymer. The purpose of the water-soluble polymer is to improve the formation of film once the composition is applied to soil and to improve the mechanical properties, e.g. strength and flexibility, of the film. Typically the film-forming mulch composition of the invention is applied to soil and, once applied, water evaporates from the composition causing coalescence or fusion of polymer particles to form polymer film. This includes the starch polymer deriving from the potato peel and/or the extract therefrom and the water-soluble polymer preferably present in the composition.

Preferably the water-soluble polymer is biodegradable. Preferably the water- soluble polymer is non-toxic.

Preferably the water-soluble polymer is selected from polyethylene glycol, hydroxyethyl cellulose, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinyl alcohol and mixtures thereof. Particularly preferably the water-soluble polymer is polyvinyl alcohol.

Preferably the water-soluble polymer has a weight average molecular weight of 5000-50000, more preferably 10000-40000 and still more preferably 12000-30000.

Preferably the water-soluble polymer has a degree of hydrolysis of 60 to 95 mol% and more preferably 80 to 90 mol%.

In preferred film-forming mulch compositions of the present invention the weight ratio of the potato peel and/or an extract therefrom to the water-soluble polymer is 100:0 to 60:40, more preferably 100:0 to 70:30 and still more preferably 100:0 to 80:20. It has been found that at these ratios strong and flexible films are formed which may be used to suppress weed growth. Advantageously the films are also able to support a range of additives within their structure, thereby facilitating the provision of films with further advantageous properties.

The amount of water-soluble polymer present in the film-forming mulch compositions of the present invention is preferably 0-40 %wt, more preferably 0-25 %wt and still more preferably 0-15 %wt, based on the total weight of the dry ingredients. Preferably the concentration of the water-soluble polymer present in the film-forming mulch composition is 0-50 g per litre, more preferably 0-30 g per litre and still more preferably 0-20 g per litre.

Cross-linking agent

The film-forming mulch composition of the present invention preferably further comprises a cross-linking agent. The purpose of the cross-linking agent is to obtain strong films and to improve the water resistance of the final film, i.e. to decrease the tendency of the film to dissolve in, e.g. rain or during watering. The cross-linking agent is believed to form cross-links within the starch deriving from the potato peel and/or the extract therefrom as well as within any water soluble polymer present and between starch and any water soluble polymer present.

Preferably the cross-linking agent is biodegradable. Preferably the cross-linking agent is non-toxic.

Preferably the cross-linking agent is selected from formaldehyde, formic acid, disodium tetraborate (borax), citric acid, epichlorohydrin, malonic acid, oxidized sucrose, glutaraldehyde, trimetaphosphate, phosphorous oxychloride, sodium tripolyphosphate, hexamethoxy methylmelamine and mixtures thereof. Still more preferably the cross- linking agent is selected from formaldehyde, formic acid, disodium tetraborate (borax), citric acid, and mixtures thereof.

It will be appreciated that some cross-linking agents require or benefit from the presence of a catalyst to initiate their cross-linking reactions. For instance, formaldehyde is typically used in conjunction with ammonium chloride. The skilled person will be aware of typical combinations.

In preferred film-forming mulch compositions of the present invention the weight ratio of the potato peel and/or an extract therefrom to the cross-linking agent is 100:0 to 60:40, more preferably 100:0 to 70:30 and still more preferably 100:0 to 80:20. It has been found that at these ratios films with high strength and flexibility are obtained. The amount of cross-linking agent present in the film-forming mulch compositions of the present invention is preferably 0-40 %wt, more preferably 0-25 %wt and still more preferably 0-15 %wt, based on the total weight of the dry ingredients. Preferably the concentration of the cross-linking agent present in the film-forming mulch composition is 0 to 50 g per litre, more preferably 0 to 25 g per litre and still more preferably 0 to 20 g per litre.

Filler

Optionally the film-forming composition of the invention further comprises a filler. The purpose of the filler is generally to increase the bulk of the film. Sometimes fillers are utilised to improve the mechanical strength of the final films.

Preferably the filler is biodegradable. Preferably the filler is non-toxic.

The fillers present in the film-forming mulch composition of the invention may be organic or inorganic or a mixture thereof. Representative examples of organic fillers include wood flour, cellulose fibre, lignin, chitosan and milled chicken feather. Representative examples of inorganic fillers include clay, talc, calcium carbonate and mixtures thereof. Preferred clays include kaolin, bentonite, montmorillonite, halloysite and layered double hydroxide.

The amount of filler present in the film-forming mulch compositions of the present invention is preferably 0-40 %wt, more preferably 0-25 %wt and still more preferably 0- 15 %wt, based on the total weight of the dry ingredients. Preferably the concentration of the filler present in the film-forming mulch composition is 0 to 50 g per litre, more preferably 0 to 25 g per litre and still more preferably 0 to 20 g per litre.

Colourant

The film-forming mulch composition of the present invention optionally further comprises a colourant. If the composition does not comprise a colourant, then the film once formed is preferably transparent. If the composition comprises a colourant, then the film once formed is preferably opaque. The ability of the film to prevent light transmission to the underlying soil helps to prevent weed growth.

Any conventional colourants may be employed in the film-forming mulch compositions of the present invention. Thus the colourants may be pigments, dyes or mixtures thereof. Preferably the colourant is a pigment. More preferably the colourant is an organic pigment or inorganic pigment. Many conventional pigments used to colour films are inorganic and comprise metals, e.g. iron and cadmium pigments have conventionally been used to provide red or orange colouring and titanium dioxide is used to provide white colour. A preferred pigment is iron oxide.

Preferably the pigment present in the film-forming mulch composition of the present invention is non-toxic. Preferably the pigment is biodegradable.

Preferably the pigment present in the film-forming composition is organic. Representative examples of organic pigments include carbon black, acetylene black and mixtures thereof.

Preferably the pigment is a light reducing pigment. Particularly preferably the pigment is carbon black. Mulch films comprising carbon black significantly reduce weed growth under the film by depriving the weeds of light.

The amount of pigment present in the film-forming mulch compositions of the present invention is preferably 0.1 -10 %wt, more preferably 0.2-7.5 %wt and still more preferably 0.5-5 %wt, based on the weight of the dry ingredients of the composition. Preferably the concentration of the pigment present in the film-forming mulch composition is 0-5 g per litre, more preferably 0.1 -5 g per litre and still more preferably 0.5-2 g per litre.

Surfactant

The film-forming mulch composition of the present invention optionally further comprises a surfactant. The purpose of the surfactant is to stabilise the polymer particles in the composition, i.e. improve their dispersion. Preferred compositions further comprise a surfactant.

Any conventional cationic, anionic or non-ionic surfactant may be used. Representative examples of suitable cationic surfactants include cetrimonium bromide, cetylpyridinium chloride, octenidine dihydrochloride, benzalkonium chloride, benzethonium chloride, dimethyldioctadecylammonium chloride and dioctadecyldimethylammonium bromide. Representative examples of suitable anionic surfactants include dioctyl sodium sulfosuccinate, perfluorooctanesulfonate, linear alkylbenzene sulfonates, sodium lauryl ether sulfate, sodium stearate and alkyl-aryl ether phosphates. Representative examples of non-ionic surfactants include octaethylene glycol monododecyl ether, pentaethylene glycol monododecyl ether, polyethylene glycol nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyethoxylated tallow amine, glycerol monostearate, polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (20) sorbitan monostearate and polyoxyethylene (20) sorbitan monooleate. Film-forming mulch compositions comprising non-ionic surfactant are particularly preferred. The total amount of surfactant present in the film-forming mulch compositions of the present invention is preferably 0-10 %wt, more preferably 0.1 -5 %wt and still more preferably 0.5-2 %wt, based on the total weight of the composition. Preferably the total concentration of surfactant present in the film-forming mulch composition is 0-10 g per litre, more preferably 0.1 -5 g per litre and still more preferably 0.5 to 2 g per litre.

Additives

The film-forming mulch composition of the invention optionally comprises one or more further additives. Examples of additives that are optionally present in the composition of the invention include binder, biocides, organic granules, polymers, fibres, pH regulator, antioxidants, enzymes to trigger biodegradation, stimuli-responsive agents to trigger biodegradation, surface modifying agents chelates, and mixtures thereof. Examples of suitable binders include vegetable oil (e.g. linseed oil, palm oil), vegetable gums (e.g. guar gum, gam arabic, acacia gum), gelatin, milk solids and waxes (e.g. paraffin wax, carnauba wax, sugar cane wax and bees wax). Examples of suitable biocides include fungicides, herbicides, pesticides, nematicides, molluscicides, anti microbial agents, and mixtures thereof. Examples of suitable organic granules include wood flour, sawdust, seeds, seed hulls, nut shells, corn cobs and bark. Examples of suitable fibres include wood pulp, shredded wood, shredded paper, shredded pine straw, shredded corn stalks, straw, flax, cotton, fibrous moss or peat moss, hair, keratin, gelatin, rayon or mixtures thereof.

Additional additives are preferably present in the film-forming mulch composition of the present invention in a total amount of 0-30 %wt, more preferably 0-15 %wt and still more preferably 0-10 %wt, based on the weight of the dry ingredients of the composition.

Composition

Preferred film-forming mulch compositions of the invention comprise:

(i) non-chemically modified potato peel and/or an extract therefrom;

(ii) a plasticiser;

(iii) water;

(iv) optionally water-soluble polymer;

(v) optionally cross-linking agent;

(vi) optionally filler;

(vii) optionally colourant; and (viii) optionally surfactant.

Further preferred film-forming mulch compositions of the invention comprise:

(i) non-chemically modified potato peel and/or an extract therefrom;

(ii) a plasticiser;

(iii) water;

(iv) water-soluble polymer;

(v) cross-linking agent;

(vi) optionally filler;

(vii) optionally colourant; and

(viii) optionally surfactant.

Yet further preferred film-forming mulch composition of the present invention comprises:

(i) non-chemically modified potato peel and/or a non-chemically modified extract therefrom;

(ii) glycerol;

(iii) water;

(iv) polyvinyl alcohol;

(v) cross-linking agent;

(vi) filler;

(vii) carbon black; and

(viii) surfactant.

Preferably the film-forming mulch composition of the invention is sprayable. This facilitates application of the composition to the soil. Conventional spray equipment may be used. Preferably the film-forming mulch composition has a viscosity of 0.1 to 20 Poise, more preferably 0.5-10 Poise and still more preferably 1 -5 Poise. This ensures that the composition is sprayable without causing blockages in the spray equipment.

Preferably the film-forming mulch composition does not comprise any external polymer other than the water-soluble polymer. This increases the biodegradability and sustainability of the film.

Preferably the film-forming mulch composition does not comprise organic solvent. Thus preferably the composition comprises less than 10 %wt organic solvent, based on the total weight of the composition. This is advantageous to reduce the volatile organic compound (VOC) content of the composition.

Containers and kits The present invention also relates to a container containing a film-forming mulch composition as hereinbefore described. Suitable containers include tins, drums, bottles and flasks.

Alternatively the film-forming mulch composition of the invention is provided in the form of a kit. The kit provides the non-chemically modified potato peel and/or an extract therefrom, plasticiser and other preferred components of the composition other than water. Preferably the water is sourced locally during preparation of the composition. Optionally the kit provides a container for mixing the components of the composition.

Manufacture

The present invention also relates to a method for preparing a film-forming mulch composition as hereinbefore described comprising:

(i) dispersing non-chemically modified potato peel and/or an extract therefrom and a plasticiser in water; and

(ii) mixing the non-chemically modified potato peel and/or an extract therefrom, plasticiser and water, preferably until it is homogeneous.

In preferred processes of the invention, the dispersion of non-chemically modified potato peel and/or an extract therefrom and plasticiser in water are heated. Preferably the dispersion is heated until gelling occurs. Typically this involves heating at 50 to 90 °C, e.g. for 5 to 60 minutes.

In further preferred processes of the invention, water-soluble polymer, if present, is added in step (i). In further preferred processes of the invention, cross-linker, if present, is added in step (i). In further preferred processes of the invention, surfactant, if present is added in step (i). In further preferred processes of the invention, filler, colourant and/or other additives are added in step (ii).

Mixing may be carried out using any conventional equipment, e.g. a stirrer. Preparation of Mulch-Film

The present invention also relates to a method of preparing a mulch film, e.g. on soil, comprising:

(i) spraying a composition as hereinbefore described; and

(ii) evaporating the water thereby forming a film.

The soil may be any soil that can be used for growing or cultivating plants, e.g. in a field, in a container, in a greenhouse or in a garden. Preferably the soil is weed-free when the composition is sprayed thereon. Preferably the soil already contains plants when the composition is sprayed thereon. Thus preferably the film-forming mulch composition is applied after the desired plants have germinated visibly and project above the soil. This means that the growth of the desired plants is not hindered by the mulch film once it forms.

Thus the invention also relates to a method of controlling weeds comprising:

(i) spraying a composition as hereinbefore described onto soil; and

(ii) evaporating said water thereby forming a film over the soil.

The weeds may be any weeds conventionally found in the environment in the relevant season. This includes grasses.

Alternatively the mulch-film may be prepared by a method comprising:

(i) casting a composition as hereinbefore described on a cast film line.

In this case, the method of controlling weed growth comprises laying a pre-cast film as hereinbefore described onto soil and fixing said film in place.

An advantage of the mulch-films of the present invention is that they may be ploughed into the soil after harvesting.

Mulch-Film

The present invention also relates to a mulch film comprising:

(i) non-chemically modified potato peel and/or an extract therefrom;

(ii) a plasticiser; and

(iii) optionally water.

Alternatively viewed the invention also provides a mulch film obtainable by:

(i) spraying a composition as hereinbefore described; and

(ii) evaporating said water thereby forming a film.

Preferred non-chemically modified potato peel and/or an extract therefrom present in the mulch film is as described above for the film-forming mulch composition. Preferred plasticiser present in the mulch film is as described above for the film-forming mulch composition. Similarly preferred water-soluble polymer, cross-linking agent, filler, colourant and surfactant, where present in the mulch film, are as described above for the film-forming mulch composition

Preferred mulch films of the present invention are biodegradable. This means that the films, over time, undergo a significant change in structure and therefore properties. Mulch films of the invention are preferably degraded by a combination of microbial action and chemical degradation, e.g. hydrolysis based degradation. Preferred mulch films of the present invention have a thickness of 10-500 mhi, more preferably 50-450 mhi and still more preferably 100-400 mhi. The thickness of the film is optionally be achieved by spraying the composition of the invention a plurality of times.

The mechanical properties of mulch film are important as it needs to retain its integrity during use and resist damage during maintenance of crops, from environmental factors such as rainfall, wind and changing temperatures and humidity. Preferred mulch films of the present invention have a tensile strength of 0.2-50 MPa, more preferably 0.3- 40 MPa and still more preferably 0.5-30 MPa, e.g. as measured according to the method described in the examples. Preferred mulch films of the present invention have a tensile strain at break of 0.2-100 %, more preferably 0.3-70 % and still more preferably 0.5-50 %, e.g. as measured according to the method described in the examples.

Preferred mulch films of the invention are opaque.

The invention will now be described by the following non-limiting examples and Figures, wherein:

Figure 1 shows the results of testing of mulch films of the invention in comparison with a control at high (H), medium (M) and low (L) application rates; and

Figure 2 shows the results of testing of two mulch films of the invention in comparison with a control at a high (H) application rate.

EXAMPLES

Materials

The dried potato peel powder and potato peel extract used in the examples was prepared as described below. The other compounds used in the examples are all commercially available.

Preparation of powdered potato peel (PPP)

Raw potato peel obtained from abrasive potato peeling was dried in a hot air oven at 60°C for 48 hours. The dried potato peel was then milled into coarse particles and subsequently milled into fine powder. The particle size of the potato peel was determined using a Malvern instrument by the light scattering method. The d (0.5) and d (0.9) of the milled potato peel powder particles was 210 pm and 550 pm respectively. The potato peel was used without any further treatment. Preparation of potato peel extract (PE)

The water washings from a potato peel process were centrifuged and the resulting product was then dried to obtain a starch-rich potato peel extract in the form of a powder. It was used without any further milling and is denoted PE herein. Preparation of film-forming mulch compositions

The compositions described in Tables 1 and 2 below were each prepared by the following steps:

1. Potato peel powder and/or potato peel extract, plasticiser, PVA and cross-linking agent were dispersed in cold water 2. The resulting dispersion was heated to 85-90 °C for 30 minutes (until gelation) with constant stirring

3. Any additional additives (e.g. catalyst or filler), if any, were added and stirring at 85-90 °C was continued for another 10 minutes.

4. The resulting solution was cast in a plastic container (in the lab) or sprayed as a solution onto soil in the field at a high dose (H - 1300 ml_/m ² ), medium dose (M - 890 ml_/m ² ) or low dose (L 445 mL/m ² ).

5. The dried film formed after 2 days at 20 °C in the lab was peeled and tested for tensile properties.

Test Methods

The tensile properties of film samples were measured according to ISO-527-3. The testing was performed on a Hounsfield tensile tester at room temperature. The dried sheet of cast film was hot pressed (at 140 °C) to provide a film with uniform thickness. The thickness of the samples was 100 - 200 pm. The resulting film was conditioned at 23°C and 50% RH for at least two days before tensile testing. At least 5 parallel test specimens with dimensions, 15 x 100 mm, were cut from the hot-pressed samples and tested for tensile properties. From stress-strain curves, the tensile strength and elongation at break were calculated.

The water vapor transmission rate (WVTR) of film samples was measured according to ASTM E 96 - 95. The standard describes the gravimetric method for the determining WVTR of materials. This gravimetric method is also referred to as the“cup” method. In this method, the impermeable cup (Teflon) is filled with water (20ml_) and later sealed with the sample whose WVTR needs to be determined. The cups were placed in a controlled temperature (28°C) and humidity (50% RH) chamber. The decrease in the weight of the cup was measured periodically by removing it from the controlled atmosphere for a brief period. In order to weigh the Teflon cup, an electronic balance with precision of 0.001 g was used. Three parallel measurements were made, and the average values are recorded.

The film samples for WVTR were prepared in the same way described above for tensile testing. Thus the dried sheet of cast film was hot pressed (at 140 °C) to provide a film with uniform thickness. The thickness of the samples was 100 - 200 pm. The resulting film was conditioned at 23°C and 50% RH for at least two days before testing. At least 3 parallel test specimens with circular dimensions, 50 mm diameter, were cut from the hot-pressed samples and tested for WVTR. Field testing was conducted on sandy soil under both rain protected and open conditions. A sandy soil was ploughed and flat squares of 1 m were prepared for each mulch treatment. Since the field tests were performed in Autumn, when some weed seeds are in dormancy, additional seeds of Poa annua and Trifolium hybridum were added to the soil as candidates for weeds (800 seeds of each per m ² ).

The mulch formulations were successfully applied onto the soil with an agricultural sprayer (NORA, Gustav A ring, at 3 BAR air pressure) with even spray nozzle (Teejet TP9506EVS, Sproytegarden AS, Kleppe, Norway). The performance of the mulch formulations was evaluated by registering the number of weeds in each of the plots after 4 weeks.

In addition, the performance of the mulch formulations was evaluated in pot trials with peat soil under both rain protected and open conditions. The pot experiment was performed in specially designed self-watering pots with 20 litre soil volume and 8 litre water reservoirs in the bottom to facilitate a watering system. A piece of fabric was used to lead water from the bottom chamber to the soil. The soil used in the pots was‘P-jord’ (Emaljunga torvmull AB, SE 28022 Vitterso) with 85 vol% sphagnum peat H2-H4 and 10 % H6-H8 and 5% fine sand. Poa annua and Trifolium hybridum was used as weed candidates. Each pot was supplied with 100 seeds of each of Poa annua and Trifolium hybridum. The mulch formulations were successfully applied onto the soil with an agricultural sprayer (NORA, Gustav A ring, at 3 BAR air pressure) with even spray nozzle (Teejet TP9506EVS, Sproytegarden AS, Kleppe, Norway). The performance of the mulch formulations was evaluated by registering the number of weeds in each of the plots after 4 weeks. The results of the lab testing are shown in Table 3 below. The results of field testing are shown in Figures 1 and 2.

ab e1

Table 2

Table 3

The tensile properties of the films measured in the lab proved that film formation occurred and that the resulting films had mechanical properties that were likely to provide the ability to suppress weed growth in the field.

The results of the field testing are shown in Figures 1 and 2. Figure 1 shows the results of testing in open fields and rain protected fields. In each case, seeds of Trifolium hybridum and Poa Annua were added as additional sources of weed to challenge the performance of the mulch film.

The results in Figure 1 show that compared to the control, where no mulch film was provided, the mulch film dramatically improved weed inhibition. In all of the conditions tested, each of the mulch films tested significantly inhibited weed germination and growth and in some cases weed germination was completely suppressed.

The results in Figure 2 show that in pot trials the mulch films of the invention greatly inhibit weed growth compared to the control wherein no mulch film was employed. The mulch films were found to be particularly effective in rain protected areas, presumably because in the absence of rain, the integrity of the mulch film was retained for a longer period of time. As with the field testing, all of the compositions tested significantly improved weed control in each of the conditions tested.