WO2003013223A1

WO2003013223A1 - Ground surface covers

Info

Publication number: WO2003013223A1
Application number: PCT/NZ2002/000153
Authority: WO
Inventors: Kevin Henry Rix-Trott
Original assignee: Kevin Henry Rix-Trott
Priority date: 2001-08-09
Filing date: 2002-08-09
Publication date: 2003-02-20

Abstract

A multi-layer, biodegradable, ground surface sheet (1) of paper or cardboard incorporates linseed oil, etc as preservative. It has a corrugated lower layer (3) providing airflow channels (6) across upper surface (10) of soil, mulch, etc, (11) over subsoil (12). Upper layer (2) of sheet (1) may be flat (as shown) or have a further layer of upward-facing corrugations. Air pockets between layers (2, 3, etc) provide insulation. Sheet (1) is urolled from a vehicle, passed through a bath so that additives such as fertiliser, fongicide, pesticide, etc, are absorbed, and then fixed to the ground using biodegradable, swellable pegs or by clipping to wires running along sides of sheet (1).

Description

GROUND SURFACE COVERS

FIELD OF THE INVENTION

This invention relates to ground cover and mulches and to the application of a sheet material to a surface. In particular it relates to a biodegradable sheet material and its use as a ground cover or soil mulch, or as an absorbent sheeting for use in 'mopping up' liquids from floor, ground, or other substantially horizontal surfaces. The invention also relates to the unrolling of a sheet material from a roll, and the laying of the sheet material on a soil, floor, or other similar, ground surface. The sheet material may incorporate additives which may be applied as a liquid treatment to the sheet material prior to laying out the sheet material on the surface.

BACKGROUND TO THE INVENTION

Material in laminar, mat or sheet form is used for covering soil or ground to inhibit or suppress plant growth, for example weed growth in the vicinity of desirable plants, or to introduce plant material or other substances into the environment. Soil mulch materials are used to block transmission of sunlight to the soil surface and to reduce loss of moisture from the soil. Such materials can be made from plastics materials having little or no biodegradability or from biodegradable materials or combinations of both. However, many of these materials are not organic nor fully biodegradable and present problems. For example, pieces of polythene mulch materials may remain in or on the soil long after the mulching effect has been lost due to partial breakdown of the material.

SUMMARY OF INVENTION

An object of the invention is to provide an improved biodegradable surface cover material or method and apparatus for laying a sheet of the material over a surface, or to provide the public with a useful choice. In one aspect the present invention may be said to consist in a substantially laminar biodegradable ground surface cover material having on at least one major face means which allow air to flow across at least a part of that face when the cover material lies on a ground surface with that face in contact with the ground surface.

Preferably the means which allow the flow of air include a series of channels.

Preferably the surface cover material is formed by at least two layers, at least one outer layer being corrugated to present the series of channels.

Preferably the surface cover material includes any one or more of a preservative, a seed, a plant growth inhibitor, a herbicide, a fungicide, an insect repellant, an insecticide, a nematicide, a pesticide, a plant nutrient or fertiliser, a superabsorbent, or a detergent.

Preferably the preservative is linseed oil.

Preferably the laminar surface cover material includes openings providing passageways between one face of the surface cover material and the other.

In a second aspect the present invention may be said to consist in a method of treating a ground surface by overlaying the ground surface with a surface cover material according to the first aspect with or without any of the above preferences.

Preferably the cover material is secured to the ground surface.

Preferably the cover material includes integral ground securing means and cover material is secured to the ground surface by the integral ground securing means.

Alternatively the cover material is secured to the ground surface by being secured to at least one elongate line which is anchored to the ground surface. Preferably the cover material is an elongate sheet which is laid between two substantially parallel elongate lines, the ends of the lines are anchored to the ground surface, and the longitudinal edges of the sheet are secured respectively to the lines at intervals along the lines.

Preferably the elongate sheet is folded over the parallel elongate lines at least where the longitudinal edges of the sheet are secured to the lines.

Alternatively the cover material is secured to the ground surface by one or more anchor pins which are driven into the ground surface.

Preferably the anchor pins are made from an absorbent material which swells upon absorption of moisture.

Preferably each anchor pin has a pair of legs which diverge when the anchor pin is driven into the ground surface.

Preferably the one or more anchor pins are biodegradable.

Preferably each anchor pin is used in conjunction with a respective load spreading means, the load spreading means spreading the load imposed by the anchor pin on at least a portion of the cover material in the vicinity of the anchor pin.

Preferably the or each load spreading means is biodegradable.

Preferably the surface is at least partly covered by one or more liquids which are at least partly absorbed by the surface cover material.

In a third aspect the present invention may be said to consist in a method of applying a sheet material to a ground surface, the material, prior to application to the surface, being formed as a roll of the sheet material, the method comprising the step of unrolling the sheet material off the roll and laying the unrolled sheet material onto the ground surface. Preferably, the outer end of the roll of sheet material is fixed relative to the ground surface, prior to completion of the step of unrolling the sheet material off the roll.

Preferably the roll of the sheet material is transported over the ground surface simultaneously with the unrolling of the sheet material off the roll.

Preferably a liquid is absorbed into the sheet material prior to the sheet material being laid onto the ground surface.

Preferably the liquid is absorbed into the sheet material after the sheet material leaves the roll but before the sheet material is laid onto the ground surface.

Preferably the sheet material is passed through a bath of the liquid after the sheet material leaves the roll but before the sheet material is laid onto the ground surface.

Alternatively the roll is soaked in the liquid prior to the sheet material being unrolled off the roll.

Preferably the liquid comprises or contains an additive.

Preferably the additive includes any one or more of a preservative, a plant seed or seeds, a plant growth inhibitor, a herbicide, a fungicide, an insect repellant, an insecticide, a nematicide, a pesticide, a plant nutrient or fertiliser, a superabsorbent, or a detergent.

Preferably the preservative is a linseed oil.

Preferably the sheet material laid onto the surface is fixed to the ground surface.

In a fourth aspect the present invention may be said to consist in an apparatus for applying a sheet material to a ground surface, the material, prior to application to the surface, being formed as a roll of the sheet material, the apparatus comprising a roll support means for supporting the roll of the sheet material while allowing the sheet material to be unrolled from the roll and laid onto a ground surface.

Preferably the apparatus includes a vehicle for travelling over the ground surface, the roll support means being carried on the vehicle.

Preferably the support means comprises a substantially horizontal support spindle.

Alternatively the support means comprises a cylindrical support container.

Preferably the support container can contain a liquid while supporting the roll of sheet material.

Preferably the vehicle includes a liquid container for containing a body of liquid through which the sheet material passes after unrolling from the roll and before being laid onto the ground surface.

Preferably the liquid container includes a constraining means which constrains the sheet material to follow a path through the body of liquid when passing from the roll to the ground surface.

The invention may further be said to consist in any alternative combination of parts or features or steps here mentioned or shown in the accompanying drawings. Known equivalents of these parts or features or steps which are not expressly set out are nevertheless deemed to be included.

BRIEF LIST OF FIGURES

Preferred embodiments of the invention will be described with reference to the drawings of which:

Figure 1 is a cross-sectional view of a first embodiment of a surface cover material, Figure 2 is a cross-sectional view of a second embodiment of a surface cover material,

Figure 3 is a cross-sectional view of the first embodiment used in a first arrangement, Figure 4 is a cross-sectional view of the first embodiment used in a second arrangement,

Figure 5 is a side view of an anchoring pin,

Figure 6 is a side view of the anchoring pin of Figure 5 when deformed after insertion in the ground, Figure 7 is a side view of the anchoring pin of Figure 5 when used to secure a surface cover material,

Figure 8 is a plan view of a cover material attached to a ground surface,

Figure 9 is a cross-sectional side view of a fragment of the cover material as seen at line A- A' of Figure 8 Figure 10 is a diagrammatic side view showing a first mode of application of a sheet material to a surface, ^!

Figure 11 is a diagrammatic cross-sectional side view of a second mode of application of a sheet material to a surface, and

Figure 12 is a diagrammatic cross-sectional side view of an alternative roll support.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to the drawings it will be appreciated that a surface cover material and the application of a sheet material to a surface, according to the invention, may be implemented in various forms. Many details of such surface cover materials, their methods of use, and apparatus for application of sheet material to a surface will be understood by a skilled reader and have been omitted. The following embodiments are given by way of example only.

Figure 1 shows a first embodiment, in which the laminar surface cover material 1 is a corrugated paper or cardboard, for example derived from wood pulp, and is formed as two layers, one substantially flat layer 2 and the other a corrugated layer 3. The flat layer is attached to peaks of the corrugated layer either by an adhesive or by the layers being integrally formed in that configuration. The laminar surface cover material thus presents one substantially flat face 4 and one corrugated face 5. The corrugated face presents an array of open channels 6. Such a material is conveniently provided in long lengths of a predetermined width and may be rolled up about an axis parallel to the length of the corrugations into a convenient and compact configuration for ease of storing and transporting the material prior to use.

The corrugations are conveniently provided as parallel corrugations and may be any shape which provides open channels. For example, the corrugations may have a sinuous shape as shown in the figures, or they may have a sawtooth or triangular or rectangular shape.

The use of the corrugated layer 3 to provide the corrugated under surface 5, forms pockets of air between the upper and lower layers 2, 3. These pockets provide an insulating effect which can help to reduce heat transmission through the cover material and thereby maintain desirable soil temperatures when used as a soil mulch.

When the surface cover material is provided in long lengths, the long edges may be provided with complementary inter-engaging features so that adjacent edges of two respective lengths of surface cover material can be joined together. For example, one edge of a length of surface cover material may be provided with cuts or partial cuts which define tabs which can be inserted into complementary slots or slits provided on an opposite edge of an adjoining length. Two or more adjoining lengths may thus be linked together to help retain the ground cover in position.

Either or both surfaces of the surface cover material may be left with their natural colour or coloured (eg green) or patterned, for example by dying, painting or printing with overlays, inks, dyes, paints, etc. The surface cover material can be coloured or patterned to improve its appearance or to contrast or blend in with a garden or landscaping scheme. The pattern, by including markings indicative of predetermined plant locations or spacings, can be used as a planting guide. The use of darker colours absorbs solar radiation which helps to increase soil temperatures.

The layers of the surface cover material and preferably any inks, dyes, paints and any adhesive used to bond the layers together, are biodegradable. The cover material is preferably 100% biodegradable and certifiable as suitable for use in "organic" environments, eg Bio-Gro certifiable.

The surface cover material is placed over a ground or soil or other surface and can be used to block the transmission of sunlight from the soil surface to suppress unwanted plant growth, such as weeds, for example around desirable plants.

The surface cover material may be provided with apertures through which desirable plants may protrude. The apertures may be provided by perforations such as holes, slots or slits. The apertures may provide planting guides for regular predetermined spacing of new plantings.

The apertures may open to an edge of the surface cover material to allow the material to be positioned around the stem, stalk, or trunk of plants already present before installation of the surface cover material. These openings to an edge of the surface cover material may be provided as slots or slits which may be fully formed or only opened, for example during installation, by fracturing frangible sections of partly cut or formed slots or slits.

The apertures may each be surrounded by a series of fully or partially cut slots or slits radiating out from the aperture so that the surface cover material can at least partly conform to an uneven ground surface in the immediate vicinity of a plant stem, stalk or trunk.

The surface cover material may be used when nursery-grown bagged tress or shrubs are newly planted out. The weed mat provides immediate protection from weed challenge especially at the early stages of plant re-establishment. Later, after the tree or shrub has become established, the weed mat decomposes naturally. Such use is particularly appropriate in domestic gardens, amenity areas e.g. public gardens and parks, reforestation, and in areas being returned to their original native habitat.

The surface cover material can include slits or other perforations to allow water or other liquids to pass through the surface cover material.

The surface cover material can include frangible sections circumscribed by incomplete cuts in the layers of the surface cover material. The frangible sections may be punched out to provide the apertures, if required, during installation of the surface cover material. Similarly the slots, slits or perforations described above may be provided by partial or incomplete cuts in the surface cover material.

Liquids or other additives can be readily included or absorbed in and retained by the surface cover material of the current invention. This is in contrast to the plastics materials which have been previously used as ground cover or mulches and which have little or no ability to absorb or retain liquids or other additives.

Substances can be incorporated into the surface cover material for application to the environment in which the material is used. For example, the surface cover material can include substances such as herbicides or other substances to suppress plant growth, or fertilisers or nutrients to promote plant growth, or fungicides, nematicides, pesticides, insecticides, or pest repellants (including animal, bird or insect repellants).

Other substances may be incorporated to preserve or extend the useful life of the surface cover material. It is preferable that any preservative used be not only organic but certifiable as such, for example Bio-Gro certifiable.

One preferred treatment is the incorporation of linseed oil as a preservative to prolong the useful life of the surface cover material as a mulch. This treatment is particularly preferred for extending the life of the cover material when it is buried under other mulch materials. The linseed oil is preferably raw but boiled linseed oil may be used instead of or in addition to the raw oil. Although the oil may be applied to the cover material by spraying, it is recognised that this method is associated with the generation of dangerous aerosols. Therefore, in the preferred method of application, the linseed oil is applied to the cover material using rollers.

The substances may be incorporated into the wood pulp slurry used at the time of manufacture of the paper or cardboard material. Water soluble substances may be dissolved in the slurry. Alternatively the substances may be carried as a suspension in the slurry.

Alternatively the substances may be incorporated after formation of the corrugated material, for example by temporary immersion in a solution or suspension, or by spraying or otherwise applying a liquid or suspension to either or both major surfaces of the already-formed corrugated material.

The surface cover material can include seeds or other viable plant propagating material which can be included in the material as already described in the previous paragraphs, or bonded to a surface of the surface cover material, for example by an adhesive. When laid over an area of ground, a surface cover material carrying seeds or viable plant material can be used to revegetate the area. The surface cover material can usefully incorporate a plant fertiliser or nutrient to enhance this revegetation process.

The additives may be incorporated into particular layers of the cover material, and the cover material may incorporate different additives in different layers. For example, the upper layer may incorporate a fungicide and or an insect repellant while the corrugated under layer may be impregnated with plant nutrients or fertilisers.

Figure 2 shows a second embodiment, in which the laminar surface cover material 7 is a corrugated paper or cardboard, having corrugations on both major faces and which is formed as three layers, one substantially flat layer 2 and two corrugated layers 3, 8 on opposite sides of the flat layer. The flat layer is attached to peaks of the corrugated⁵ layers either by an adhesive or by the three layers being integrally formed in that configuration. The laminar surface cover material thus presents two corrugated faces 5, 9. Each corrugated face presents an array of open channels 6. The corrugations are conveniently provided as parallel corrugations and may be any shape which provides the open channels. For example, as in the first embodiment, the corrugations may have a sinuous shape as shown in the figures, or they may have a sawtooth or triangular or rectangular shape.

If the corrugations on opposite faces are aligned, ie are substantially parallel, the material may be rolled up as discussed above. In an alternative arrangement the corrugations on opposite faces are not aligned, for example they can be mutually perpendicular, in which case the surface cover material is not readily rollable but lends itself to use as substantially flat sheets.

All variations discussed above in relation to the embodiment having a single corrugated face can be applied to the embodiment having corrugations on both major faces.

The surface cover material is laid out over a ground surface with the, or a, corrugated surface on the underside. The cover material may be secured to the ground, for example by pins or pegs as will be explained further below. The corrugations provide channels though which air may move to allow oxygenation or aeration of the soil surface.

Figure 3 shows a surface cover material 1 according to the first embodiment laid over the surface 10 of a mulch layer 11. The mulch layer may comprise a particulate mulch material such as bark chips, or fine soil for establishing seedlings or for germinating seeds. The mulch layer 11 is laid over a subsoil layer 12. The channels 6 on the underside of the surface cover material provide passages through which air can pass. In this way the soil and mulch surface can remain aerated to help maintain the condition of the soil.

Figure 4 shows a surface cover material 1 A according to the first embodiment laid over the surface 10 of a mulch layer 11. The mulch layer 11 is laid over a subsoil layer 12. A second layer of surface cover material IB according to the first embodiment is laid over the subsoil layer 12 before the mulch layer 11 is put down. Again the channels 6 on the underside of both layers of cover material provide passages through which air can pass.

In a further alternative, not shown, the upper surface cover material 1 A of Figure 4 is omitted and the mulch layer is used to cover and secure the remaining layer of lower surface cover material IB in place on the soil.

Alternatively, the channels 6 facilitate movement of liquids, eg oil or water, across a surface on which the material is over-lain.

The surface cover material, as a soil cover, provides protection against erosion of the soil (eg by wind and rain), blocks' transmission of sunlight to the soil surface, and reduces loss of moisture from the soil.

The ground cover is suitable for revegetating exposed bare soil surfaces, and provides temporary protection while new plant growth is established. One such application is revegetating areas adjacent recently constructed or altered roads and motorways.

The ground cover is also suitable for use in establishing forestry plantings and new horticultural crops, for example orchards, vineyards and market gardens. Because the surface cover material is biodegradable it does not need to be removed when it is no longer needed or when the new plantings are established. The surface cover material can be ploughed into the soil, for example after cropping, or just left to break down and rot away. The useful life of the ground cover can be extended by incorporating a mould inhibitor or bactericide in a manner similar to that already described above in relation to the aforementioned additives.

In the cases where the added substances are water soluble, the added substances are expected to leach out onto plant growth over which the ground cover is laid or into the underlying soil, to suppress weed growth, or enhance plant growth, or inhibit or discourage pests, diseases, etc, as appropriate to the particular additive or additives used. The ground cover is particularly suitable for use in 'organic' situations or environments where only natural products and materials may be utilised. For such applications the ground cover can be produced as an entirely natural product without any artificial or synthetic additions.

In use, the ground cover materials may be covered by other mulch material such as chips or pieces of bark, or pea metal, etc.

In an alternative method of use of the surface cover materials described above, the surface cover material is used to absorb or 'mop up' liquids from ground surfaces. One such application is after a spill of oil, diesel or petrol such as may occur as a result of a road or motorway accident. Such spills can make the road surface very slippery, which can lead to further accidents, and can require closure of the road while the spill is dealt with.

Detergents are often used to neutralise spills of oils and other petroleum products. This treatment enables such spills to be washed away, but this can be a time consuming measure during which the road surface cannot be used by vehicular traffic with a satisfactory degree of safety. It is also known to spread particulate or granulated absorbent material, for example sawdust, over a liquid spill to absorb liquid. While effective in absorbing liquid, the particulate or granulated material is then not readily removed from the road surface which also delays return of the road to full use.

The laminar surface cover material described above can be spread out over the site of the spill by emergency or rescue service personnel to absorb the liquid and to simultaneously provide improved grip for vehicles traversing the area of the spill. Thus the road can be used, albeit with reduced vehicular speeds, without further delay.

The absorbent surface cover material can also be used in 'mopping up' liquids such as oils or water after spills or floods in buildings, eg homes, factories and warehouses, etc. The absorbency of the surface cover material can be enhanced by the inclusion of absorbents which bind absorbed liquids by capillary action such as sawdust, wood fibres or other fibrous material, and/or by the inclusion of absorbents which bind absorbed liquids by chemical action. Superabsorbents polymers, for example in fibrous and powder forms, and gels are known to be suitable for such a purpose.

Where materials binding liquids by capillary and chemical action are both used, the capillary action material can transport liquids from the surface of the surface cover material to the chemical action material.

Where liquid has been spilled on a road surface the road can be used by traffic as soon as the spill is covered with the laminar surface cover material which continues to absorb the spilt liquid. If the absorbent capacity of a single layer of surface cover material is not sufficient to absorb the quantity of liquid spilled, additional layers can simply be added over the first. The surface cover material, while absorbing the spilled liquid, provides an improved grip between vehicle tyre and road surface or a relatively clean and non-slippery surface for traversing by foot. After use, the surface cover material with the absorbed liquid is simply rolled, or otherwise gathered up, and removed for treatment or disposal.

A suitable surface cover material for absorbing liquid spills can have corrugations on one or both major surfaces. If the corrugations on opposite major surfaces are aligned, the material can be rolled up for convenience of storage and transport.

The use of a surface cover material for removal of oil or other spills provides a fast and effective clean-up strategy without the release of chemicals or other substances into the environment. If necessary liquids absorbed by the surface cover material can be retrieved by applying mechanical pressure to the material, for example by passing it between a pair of rollers as will be explained further below.

It is preferable when the cover material is used as a mulch, that any method of retaining the material in place use materials that degrade naturally so that later retrieval and disposal problems do not arise. It is also preferable that any retaining device spread the retaining load to at least reduce the likelihood of the retainer being pulled through the cover material. The edges of the cover material may be folded and/or covered by soil or particulate mulch materials, e.g. bark chips.

In one self-retention arrangement, not shown in the figures, the cover material is fonned into fingers that are inserted into the ground, e.g. by punching, to retain the cover material in place. This arrangement avoids the need to introduce other materials and the associated additional cost. It may be necessary to add a tape to the fingers to strengthen the fingers for use in hard ground conditions.

The cover material may be secured or anchored to the ground by a pin or peg. Preferably the pin or peg is not only biodegradable but also appears to the general public to be biodegradable, for example, it is not of a plastics material.

Figure 5 shows a suitable peg 53 which deforms upon insertion into the ground to provide a positive anchor. The peg has a head 54 and a longitudinal split 55 extending from below the head. The split defines two legs 56 which diverge upon insertion into the ground as shown in Figure 6. A bevelled face 57 is provided on the inside surface at the end of each leg. As the peg 53 is driven onto the ground, the bevelled faces 57 react against the ground to force the legs apart. The peg may include a hole 58 at the upper end of the split to reduce the likelihood that any further splitting or cracking of the peg does not propagate to the top of the pin.

The pin is preferably manufactured from a material that swells after insertion in the ground, by absorption of moisture. Preferably the pin is made from a pressed sheet, for example a sheet of medium density fibreboard (MDF). It is expected that any trace of formaldehyde left in the MDF will not cause a significant effect on the soil environment or on any overlying mulch.

Alternatively, the pin may be made from an untreated wood such as from pinus radiata. Figure 7 shows the peg 53 inserted into the ground 59. After insertion of the pin through the cover material into the ground, a load spreading disc or washer 60 is pushed down over the head 54 of the peg 53 to spread the anchoring load on the surrounding cover material 61. The disc or washer 60 may be made from a high density cardboard. The head of the peg can be provided with notches 62 to engage and retain the load spreading disc or washer 60 in place on the peg 53.

If the peg splits into two halves, the two halves may be kept together by the cardboard disc or washer surrounding the head of the pin.

Figures 8 and 9 show an alternative method of securing the cover material to a ground surface. This alternative method is particularly suitable for securing long lengths of cover material, for example when the cover material is used as a mulch layer between two crop rows. In this method an elongate sheet of cover material 70 is laid over a ground surface 71. Two lines 72 are also laid on the ground surface, one on each side of the mulch material.

The lines 72 are anchored, for example by weights or pegs 73, to the ground 71 at either end of the lines, and optionally at intermediate positions 74 along the lines. The optional additional anchoring is particularly suitable for securing long lengths of mulch material, or where ground contours are such that additional anchoring is needed to keep the mulch material on the ground surface, or where it is likely that the lengths of mulch material could be dislodged by wind. The lines 72 may be rope, string, nylon mono- filament, cord or wire, for example, or any similar material having a sufficient tensile strength.

The mulch material is secured to the lines at intervals along the length; for example at intervals of about lm. The mulch material may be secured to the lines by pegs or clips 75. An edge portion of the mulch material may be folded over the line where the pegs or clips are attached. Figure 9 shows a cross-sectional side view of a fragment of the mulch material 70 laid over a ground surface 71. An edge portion of the mulch material 70 is folded under itself and about the line 72 and secured to the line by a clip 75. The clip may be a wire staple.

Figure 10 shows a mode of carrying out the current method. A roll 21 of a sheet material 22 is laid on its side on a surface 23 on which the sheet material is to be laid. The roll is simply rolled along the surface 23 in direction A to unroll and lay out the sheet material onto the surface. The sheet material 22 may be the cover materials 1, 7 described above.

The outer end of the sheet material may be fixed to the surface 23 such as by a peg 24, for example as described above, or a weight 25 to restrain the end of the sheet as the roll is advanced in direction A.

Before unrolling and laying out the sheet material, the roll 21 of sheet material is pre- soaked in a liquid or slurry, not shown, to soak the sheet material and preferably load the sheet material with an additive included or suspended in the liquid. Typical additives include seeds, a plant growth inhibitor, a herbicide, a fungicide, an insect repellant, an insecticide, a nematicide, a pesticide, a plant nutrient or fertiliser, a superabsorbent or a detergent.

The additives can leach from the sheet material over an extended period. The leaching may be helped by natural precipitation or the artificial application of irrigation water. Additionally, or alternatively the additives may be released upon natural breakdown of the sheet material. To this end the sheet material is manufactured from a bio-degradable material, for example a wood pulp material such cardboard or paper.

In one preferred use, the sheet material, after pre-soaking, is laid out onto a ground surface as a mulch in a horticultural enviromnent. The method has particular application as a mulch for horticultural crops grown in extended rows in substantially straight lines. Typical of such crops are grape vines. Long lengths of sheet material are unrolled and laid on either side of the main stems of a row of grape vines. The sheet material acts as a mulch, blocking sunlight from the soil, inhibiting weed growth and/or adding soil deficiencies, trace elements or other substances to the soil.

In one preferable implementation in a vineyard, the sheet material is soaked in a liquid containing soil supplements and other materials including a herbicide to suppress weed growth in the vicinity of the vines. The supplements may be selected to address soil deficiencies in the region where the vineyard is located, or preferably in the particular vineyard itself, and even more preferably within a particular micro-site within the vineyard. The method allows the use of a mulch with additives targeting the needs of particular crops in a particular locality.

A roll of suitable sheet material is soaked in a drum or other container containing the selected additives which are mixed, dissolved or suspended in sufficient diluting liquid, for example water. When the material is sufficiently soaked, it is removed from the container. Excess liquid is drained from the soaked roll and the sheet material is applied to the ground surface while still damp or wet.

The sheet material, after soaking, yields more readily than if dry and therefore readily conforms to the contours of the ground surface on which it is laid. The sheet material, once laid, is helped to remain in position by the additional weight of the retained liquid.

As seen in Figure 10, pegs 24 or weights 25 may be used to fix the sheet material 22 to the ground surface 23. These fixings are particularly useful to locate the first laid, outer end of the roll as seen in Figure 10. Weights may be conveniently provided by stones or piles of soil taken from the ground on which the sheet material is being applied. Additional fixings may be added along the rolled out length as required.

Figure 11 shows an alternative method and apparatus for applying a sheet material 22 to a surface 23. The material is initially provided in a roll 21 which is mounted on a vehicle 26 carrying a roll support such as spindle 27. The spindle may be supported at both ends or may be cantilevered from a spindle support 28. The vehicle 26 may be self-powered or may be a trailer vehicle for towing behind a tractor vehicle, not shown. The vehicle may be provided with wheels 29. Alternatively the vehicle may be a track- laying vehicle or it may run on skids, not shown.

The sheet material is preferably pre-soaked in a liquid or slurry as already described above. Additionally or alternatively, the sheet material may be passed through a bath 30 containing a liquid 31. The sheet material is passed below a restraining bar or roller 32 which ensures the sheet material is passed under the surface of the liquid in the bath. The leading and trailing edges of the bath may be provided with smooth rounded surfaces or rollers 33, 34 as shown in Figure 11. The first laid, outer end 35 of the sheet material may be fixed to the surface 23, for example as already described above.

In use the roll 21 of sheet material is mounted on the spindle 27 and the outer end passed under the restraining bar or roller 32 in the bath 30. The sheet material can be drawn off the top of the roll as shown in Figure 11, or alternatively can be drawn off the bottom of the roll, similar to the arrangement as shown in Figure 10. The bar or roller may be removable to facilitate feeding the sheet material under the bar or roller. The bath is filled with liquid 31 which may contain selected additives and the outer end of the sheet material fixed to one end of the surface 23 to which the sheet material is to be applied.

The vehicle 26 traverses in direction B along the surface 23 and the sheet material 22 is unrolled off the roll 21 and paid out to lie on the surface 23.

Additional fixings, for example pegs or weights, not shown in Figure 11, but as described above, may be used to help retain the sheet material 22 in position on the surface 23.

Figure 12 shows an alternative roll support arrangement provided by a generally cylindrical dished container 40 in which the roll lies. The container 40 is provided with a smooth edge 42 over which the sheet material 22 passes in direction C as it unrolls from the roll 21. The edge may be rounded and/or may be provided by a roller 44, as shown, to facilitate the easy passage of the sheet material from the roll.

The dished container may be filled with liquid, not shown, so that at least the lower portion of the roll of sheet material is sitting in the liquid just prior to being unrolled.

The liquid in bath 30 in Figure 11 or the dished container 40 in Figure 12 can be replenished to maintain a sufficient depth of liquid during unrolling and application of the sheet material to a surface. The replenishment can be arranged to proceed automatically from a tank, for example using a float valve to maintain the desired level in the bath or dished container.

In one preferred embodiment, a ground cover material is made from a wood pulp in the form of a corrugated cardboard formed from two layers; one being substantially flat and the other being corrugated. The corrugated cardboard is organic and fully biodegradable.

The sheet material is conveniently provided as a roll of a long length of a predetermined width with corrugations, if any, extending parallel to the width. When rolled up, the material is in a convenient and compact configuration for ease of storing and transporting prior to application to a surface. The sheet material, being initially dry, is relatively light in weight during delivery to the application site. Any additives may be supplied in a concentrated form for dilution with water which is normally readily available at most application sites.

Incorporation of additives for application to the soil or soil surface, as a liquid absorbed in a solid sheet material carrier, can reduce the risk of mis-application which often accompanies other application methods. Sprays of aerosols, mists, or liquid droplets are often accompanied by problems of spray drift, especially in windy or breezy conditions. Problems with spray drift can even occur in what appears to be still conditions. Over-spray or spray drift can be a particular problem when, for example, unwanted weeds are being sprayed with herbicide in close proximity to the accompanying crop. Damage to the wanted crop often accompanies control of unwanted pests and weeds by application of a spray.

Replacement of spray application by the current methods reduces the likelihood of misapplication of chemicals, reduces wastage by applying materials only to defined target sites and can also reduce the likelihood of ingestion of air-borne materials by applicators and other people living or working in the vicinity of application.

Other possible advantages of using a solid sheet material over a soil surface are encouragement of worms to the soil surface and control of erosion by shielding the soil surface from direct impact by wind and water, for example artificial irrigation or natural precipitation.

The sheet material may also be used in planting out new crops. For example, a biodegradable sheet material may be passed through a liquid containing a herbicide and a paste loaded with crop seeds. By arranging the restraining roller to be only partly immersed in the liquid, the seeds are generally adhered only to the under side of the sheet material. After the sheet material is laid on the ground, the seeds, being on the underside of the sheet material, are largely protected from direct sun and from scavenging birds.

The herbicide acts to suppress any weed growth present and is chosen to be inactive by the time the seeds germinate. Upon germination the seedlings penetrate through the sheet material which nevertheless remains largely in place to act as mulch around the developing crop. For this purpose the sheet material can be organic and fully biodegradable. After harvesting the sheet material can be simply left to rot or it can be ploughed into the soil.

In another application, the sheet material is laid on a surface to collect or 'mop up' liquid such as a petrol or oil spill, for example on a roadway. In this application the sheet material may be pre-soaked or passed through a bath containing an appropriate super-absorbent or a detergent or other material to improve the take-up of the liquid being collected, and preferably while inhibiting absorption of the underlying water or other liquid.

The sheet material may also be laid out, similarly to as described above, over a liquid surface such as to clean up an oil spill in a marine environment or on a waterway. To this end the vehicle is suitably a water-borne vessel, for example a boat or barge, and the sheet material may incorporate entrapped air to provide sufficient buoyancy to maintain the sheet material on the surface.

The sheet material may be fibrous of cellular, and may trap air in the fibrous or cellular material itself. Alternatively, air may be trapped in the form of the material, e.g. the material may be a corrugated cardboard and the air trapped in the channels provided by the corrugated layer. Furthermore, air may be trapped by voids in the material being sealed by swelling of the material as it absorbs liquids.

The sheet material is retrieved after the liquid being collected has been absorbed into the sheet material. Retrieval may be achieved, for example, by generally reversing the roll- out procedure and re-rolling the sheet material into a roll for possible collection of the oil or other spilled liquid and/or for transportation of the rolled sheet material to a disposal site.

In this application the roll spindle 27 may be rotatably driven to help in re-rolling the sheet material. The bath roller 32 may be paired with an additional roller, for example roller 33, or a further roller not shown in Figure 2, between which the retrieved sheet material is passed prior to being re-rolled. The collected liquid absorbed into the sheet material 22 is squeezed from the sheet material by pressure applied between the pair of rollers. This liquid may be collected in the bath 30 for reuse after refining, or for disposal.

Claims

CLAIMS:

1. A substantially laminar biodegradable ground surface cover material having on at least one major face means which allow air to flow across at least a part of that face when the cover material lies on a ground surface with that face in contact with the ground surface.

2. The cover material of claim 1 wherein the means which allow the flow of air include a series of channels.

3. The cover material of claim 2 wherein the surface cover material is formed by at least two layers, at least one outer layer being corrugated to present the series of channels.

4. The cover material of any preceding claim wherein the cover material includes any one or more of a preservative, a seed, a plant growth inhibitor, a herbicide, a fungicide, an insect repellant, an insecticide, a nematicide, a pesticide, a plant nutrient or fertiliser, a superabsorbent, or a detergent.

5. The cover material of claim 4 wherein the cover material includes linseed oil.

6. The cover material of any preceding claim wherein the cover material includes openings providing passageways between one face of the surface cover material and the other.

7. A method of treating a ground surface by overlaying the ground surface with a surface cover material according to any one of claims 1 to 6.

8. A method of treating a ground surface as claimed in claim 7 wherein the cover material is secured to the ground surface.

9. A method of treating a ground surface as claimed in claim 8 wherein the cover material includes integral ground securing means and the cover material is secured to the ground surface by the integral ground securing means.

10. A method of treating a ground surface as claimed in claim 8 wherein the cover material is secured to the ground surface by being secured to at least one elongate line which is anchored to the ground surface.

11. A method of treating a ground surface as claimed in claim 10 wherein the cover material is an elongate sheet which is laid between two substantially parallel elongate lines, the ends of the lines are anchored to the ground surface, and the longitudinal edges of the sheet are secured respectively to the lines at intervals along the lines.

12. A method of treating a ground surface as claimed in claim 11 wherein the elongate sheet is folded over the parallel elongate lines at least where the longitudinal edges of the sheet are secured to the lines.

13. A method of treating a ground surface as claimed in claim 8 wherein the cover material is secured to the ground surface by one or more anchor pins which are driven into the ground surface.

14. A method of treating a ground surface as claimed in claim 13 wherein the anchor pins are made from an absorbent material which swells upon absorption of moisture.

15. A method of treating a ground surface as claimed in claim 13 or claim 14 wherein each anchor pin has a pair of legs which diverge when the anchor pin is driven into the ground surface.

16. A method of treating a ground surface as claimed in any one of claims 13, 14 or 15 wherein the pins are biodegradable.

17. A method of treating a ground surface as claimed in any one of claims 13 to 16 wherein each anchor pin is used in conjunction with a respective load spreading means, the load spreading means spreading the load imposed by the anchor pin on at least a portion of the cover material in the vicinity of the anchor pin.

18. A method of treating a ground surface as claimed in claim 17 wherein the load spreading means are biodegradable.

19. A method of treating a ground surface as claimed in any one of claims 7 to 18 wherein the surface is at least partly covered by one or more liquids which are at least partly absorbed by the surface cover material.

20. A method of applying a sheet material to a ground surface, the material, prior to application to the surface, being formed as a roll of the sheet material, the method comprising the step of unrolling the sheet material off the roll and laying the unrolled sheet material onto the ground surface.

21. A method of applying a sheet material to a ground surface as claimed in claim 20 wherein the outer end of the roll of sheet material is fixed relative to the ground surface, prior to completion of the step of unrolling the sheet material off the roll.

22. A method of applying a sheet material to a ground surface as claimed in claim 20 or 21 wherein the roll of the sheet material is transported over the ground surface simultaneously with the unrolling of the sheet material off the roll.

23. A method of applying a sheet material to a ground surface as claimed in claim 20, 21 or 22 wherein a liquid is absorbed into the sheet material prior to the sheet material being laid onto the ground surface.

24. A method of applying a sheet material to a ground surface as claimed in claim 23 wherein the liquid is absorbed into the sheet material after the sheet material leaves the roll but before the sheet material is laid onto the ground surface.

25. A method of applying a sheet material to a ground surface as claimed in claim 24 wherein the sheet material is passed through a bath of the liquid after the sheet material leaves the roll but before the sheet material is laid onto the ground surface.

26. A method of applying a sheet material to a ground surface as claimed in claim 23 wherein the roll is soaked in the liquid prior to the sheet material being unrolled off the roll.

27. A method of applying a sheet material to a ground surface as claimed in any one of claims 23 to 26 wherein the liquid comprises or includes an additive.

28. A method of applying a sheet material to a ground surface as claimed in claim 27 wherein the additive' includes any one or more of a preservative, a plant seed or seeds, a plant growth inhibitor, a herbicide, a fungicide, an insect repellent, an insecticide, a nematicide, a pesticide, a plant nutrient or fertiliser, a superabsorbent, or a detergent.

29. A method of applying a sheet material to a ground surface as claimed in claim 27 wherein the additive includes a preservative and the preservative is a linseed oil.

30. A method of applying a sheet material to a ground surface as claimed in any one of claims 20 to 29 wherein the sheet material is fixed to the ground surface.

31. An apparatus for applying a sheet material to a ground surface, the material, prior to application to the surface, being formed as a roll of the sheet material, wherein the apparatus includes a roll support means for supporting the roll of the sheet material while allowing the sheet material to be unrolled from the roll and laid onto a ground surface.

32. An apparatus for applying a sheet material to a ground surface as claimed in claim 31 wherein the apparatus includes a vehicle for travelling over the ground surface, the roll support means being carried on the vehicle.

33. An apparatus for applying a sheet material to a ground surface as claimed in claim 31 or claim 32 wherein the support means comprises a substantially horizontal support spindle.

34. An apparatus for applying a sheet material to a ground surface as claimed in claim 31 or claim 32 wherein the support means comprises a cylindrical support container.

35. An apparatus for applying a sheet material to a ground surface as claimed in claim 34 wherein the support container can contain a liquid while supporting the roll of sheet material.

36. An apparatus for applying a sheet material to a ground surface as claimed in any one of claims 31 to 35 wherein the vehicle includes a liquid container for containing a body of liquid through which the sheet material passes after unrolling from the roll and before being laid onto the ground surface.

37. An apparatus for applying a sheet material to a ground surface as claimed in claim 36 wherein the liquid container includes a constraining means which constrains the sheet material to follow a path through the body of liquid when passing from the roll to the ground surface.

38. A substantially laminar biodegradable ground surface cover material, substantially as herein described with reference to the accompanying drawings.

39. A method of treating a ground surface, substantially as herein described with reference to the accompanying drawings.

40. A method of applying a sheet material to a ground surface, substantially as herein described with reference to the accompanying drawings.

41. An apparatus for applying a sheet material to a ground surface, substantially as herein described with reference to the accompanying drawings.