Composting is the aerobic transformation of organic matter into humic substances. It is a natural process which occurs in soil, farmyard manures and on the forest floor with the production of leaf mould. Composting can be artificially hastened by gathering the organic matter together to form a heap often in a purpose made plastic container (compost bin) so as to conserve the metabolic heat of the microbial biomass. This enhanced process has three stages : - 1. A thermophilic stage which involves an initial rapid growth of the microbial population sustained by simple sugar compounds. The temperature rapidly rises to between 60 and 70°C.

2. A mesophilic stage in which the temperature falls to between about 25°C and 45°C due to the inhibition of the various thermophilic bacteria, fungi and actinomycetes at the high temperatures obtained during the thermophilic stage. At this stage, the biomass is sustained by the breakdown of cellulose and hemicellulose.

3. A maturation stage which is the final stage in composting and which is characterised by the breakdown of lignin by the higher fungi.

To optimise the efficiency of the composting process, several factors are important : - 1. High aeration (i. e. oxygen concentration greater than 10%).

2. A short thermophilic stage followed by a well-maintained mesophilic stage.

3. A correctly balanced moisture content (approximately 40 to 60%).

4. A balanced carbon/nitrogen ratio, Old plant tissue is high in carbonaceous material but low in nitrogen, whereas young green plant material is higher in nitrogen and also water. An experienced composter will try to balance the carbon/nitrogen ratio by forming the compost heap from a suitable mixture of starting materials.

5. A pH of between about 5.5 and 8.

Traditionally, compost was made in slat-sided wooden compost bins. These allow high aeration rates and the dissipation of excess moisture. However, they are considered to be too big and too expensive for modern small domestic garden use. Plastic versions of these slat-sided compost bins are also known, but suffer from similar disadvantages.

It is also known to use moulded plastic bins for composting, but these usually have restricted top access, which makes loading and turning compost difficult. Also, most, if not all, of household plastic compost bins are poorly designed and do not take into account that composting is an aerobic process.

By restricting airflow and preventing the dissipation of excess moisture generated during the thermophilic phase, most plastic compost bins may actually inhibit the composting process rather than enhance it.

It is an object of the present invention to provide an improved composting container which enables high aeration and moisture dissipation whilst being simple to use and relatively inexpensive.

According to the present invention, there is provided a composting container comprising a body in which, in use, organic material to be composted is stored, said body being defined by a tubular, permeable, non-self-supporting, flexible sheet material; top and bottom openings in the body; and support means for holding at least part of the flexible sheet material in an erected condition.

Preferably, the flexible sheet material forming the body is a substantially non-biodegradable material and may be a mesh type plastics material, for example, a polyethylene mesh fabric having a grade in the range of between 40 and 550 g/m2. Alternatively, the material may be a polypropylene net of 1-5 mm thickness and 1-10 mm hole size. The material forming the body is most preferably UV resistant. The length of the body is optimally about 1 m. However, its radius can be 20 to 60 cm, with 30 to 40 cm being optimal.

Preferably, closure means are provided for at least partially closing at least one, and preferably both, of the top and bottom openings. Such closure means may take the form of respective drawstrings or the like around the openings.

In one series of embodiments, the support means comprises a self-supporting liner which is adapted to be inserted into the flexible sheet material to hold at least part of the latter in the erected condition.

Preferably, the liner comprises a sheet of plastics material which can be rolled to form a collar, and more preferably retained in that condition by a clip or other retaining fastener. Insertion of the collar into the flexible sheet material serves to retain the latter in its erected condition at least over the depth of the collar.

The collar can be made from polypropylene or HDPE (high density polyethylene) of 0.5-5 mm thickness, preferably 2 mm. The collar dimensions will vary depending upon the length and radius of the body but will generally be 140 to 400 cm long and 30 to 80 cm wide, optimally 40 to 60 cm wide. For a body with a length of 1 m and a radius of 30 cm, the filling collar will optimally be formed from a 200 x 50 cm rectangular sheet.

In a second, preferred, series of embodiments, the support means comprises a frame having at least one resiliently deformable pre-shaped member. The or each pre-shaped member may be, for example, metal or plastics material and is conveniently of circular cross section. Preferably, the frame forms a base and a top connected by an intermediate, preferably helically coiled, flexible region (i. e. the intermediate region is effectively a coiled spring). In a highly preferred embodiment, the base, the top and the intermediate region are constituted by a single resiliently deformable frame member. For example, the frame member can be shaped to form a pair of (almost complete) circles interconnected by the helically coiled region. Preferably, the or each pre-shaped frame member is stitched or otherwise attached to the inside of the flexible sheet material. For example the frame members can be held inside pockets, sleeves or channels provided in the flexible sheet material. Where the frame comprises a base, it will be understood that the composting container is self standing.

In a highly preferred embodiment, the or each pre-shaped frame member is resiliently deformable from a position in which the composting container is erect to a position in which the composting container is compressed (eg."flat packed"for ease of storage/transport). It will be understood that when the helically coiled region is present it serves as a spring tending to return the composting container to its erect condition.

Releasable retaining means are preferably provided to retain the frame/composting container in its compressed condition. The retaining means may comprise one or more clips. Alternatively, the retaining means may comprise a cap of flexible material (eg. plastics material) which surrounds the frame in its compressed state. Preferably, the cap is held in place by a draw string.

Preferably, the composting container further comprises a lid which is insertable into the body through the top opening to rest against the material being composted in the body in use so as to limit ingress of rain. The lid can be made from polypropylene or HDPE of 0.5 - 5 mm thickness, preferably 2 mm Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Fig 1 is a schematic perspective view showing individual components of one example of composting container according to the present invention, Fig. 2 is schematic perspective view showing the composting container of Fig. 1 in a filling configuration, Fig. 3 is a schematic perspective view showing the composting container of Fig. 1 in a composting configuration, Fig. 4 is a schematic perspective view of a second example of a composting container according to the present invention in an erect condition, and Fig. 5 is a schematic perspective view of the container of Fig. 4 in a compressed condition.

Referring now to Fig. 1, the composting container comprises a body 10 defined by a cylinder of UV resistant polyethylene close mesh fabric. In this embodiment, the close mesh fabric was of the type available from Manfred Huck GmbH & Co. KG. Because of its material of construction, the body 10 is air-and water-permeable and is not self-supporting. Top and bottom openings 12 and 14, respectively, are closable by means of respective drawstrings 16 and 18. The composting container further comprises a support collar 20 which is erected by rolling a length of rectangular polypropylene sheet 22 having a thickness of 2mm and retaining in the form of a collar by means of a retaining clip 24.

In use, referring now to Fig. 2, the collar 20 is first inserted into the body 10 with the top opening 12 fully open and the bottom opening 14 closed down by means of the drawstring 18. The collar 20 is inserted until it abuts against the drawn-in portion of the body 10 around the bottom opening 14. The upper part of the body can then be folded down as shown in Fig. 2 so that a small part of the collar 20 protrudes upwardly from the body 10 to hold the lower part of the body in an erected condition with its top fully open. Then, organic material 26 to be composted is introduced into the body 10. As necessary, the folded-down portion of the body 10 is folded back and the collar re-positioned accordingly to permit more organic material 26 to be added until the body 10 is full or until no more organic material 26 is required to be composted in that batch.

Following this, and as shown in Fig. 3, the collar 20 is removed from the body 10, and a plastics rain lid 28 is inserted into the body 10 so that it rests on the top of the organic material within the body 10. The drawstring 16 is then tightened to close down the top opening 12, and then the container is left undisturbed for composting to take place.

After completion of composting, the resultant humic material can be readily removed from the body 10 by releasing the bottom drawstring 18 and lifting and shaking the body 10 to cause the humic material to flow out of the bottom opening 14 onto the ground.

The body 10, because of its material of construction, enables enhanced aeration during composting and prevents moisture accumulation, resulting in an increased rate of composting compared with that of conventional plastic compost containers, as shown in the Experiment below.

Referring now to Fig 4, another embodiment of the composting container is shown in which the cylindrical body 30 of the composting container is substantially the same as that shown in Figure 1, except that a pocket or sleeve is provided on the inside of-the cylinder formed by the mesh fabric (not shown). In other embodiments (not shown) the pocket may be on the outside of the cylinder. The pocket extends around the base of the cylindrical body 30, helically spirals to the top of the cylindrical body 30 and extends around the top of the cylindrical body 30. Held within the pocket is a flexible green spring metal frame member 32 of 6 mm diameter (in other embodiments, depending, inter alia, on the on the size of the container, the diameter of the member may conveniently be from 3 to 10 mm. In addition, in some embodiments a flexible plastics member may be preferred). The frame member 32 is pre-stressed (pre-shaped) so that it adopts the shape of the pocket, i. e. it comprises a pair of (almost complete) circles 32a, 32b connected by a helical spiral portion32c. As shown in Fig. 4, the metal frame member 32 is sufficiently rigid that the composting container is self standing and the polyethylene mesh fabric body 30 is retained in its cylindrical shape. It would be possible for a plurality of metal frame members to be used (eg. two circles joined to a helical spiral), however the advantage of using a single frame member 32 is that it can be easily fed into the pocket in a single operation.

Although sufficiently rigid to maintain the shape of the composting container, the metal frame member 32 is resiliently deformable and can be compressed in a similar manner to a helically coiled spring. Downward pressure on the top of the container compresses the frame member 32 (and the body 30 of the container in which it is secured) to the compressed"flat pack"configuration shown in Fig. 5. It will be understood that, as with a spring, because the frame member 32 is pre-stressed, it will return to the configuration shown in Fig 4 unless held in place. For this purpose a cap (not shown) formed from a flexible sheet of polythene (although any rain proof flexible material may be used) is provided. The cap envelops the compressed container and is tightly secured around it by a drawstring.

The container is conveniently stored or transported in its compressed state.

When required for composting the drawstring of the cap is released and the cap removed. The metal frame member immediately returns to its pre- stressed configuration restoring the body 30 of the container to its operating configuration of Fig. 4. The cap may then serve as a lid for the composting container when loaded with organic material. The cap may be in addition to or in place of the lid shown in Fig 3.

Experiment A composting container of the type described with reference to Figs 1 to 3 where the body 10 was 1 m long and 0.6 m in diameter and was made from 200 g/m2 polyethylene close mesh material was filled with 40 kg grass clippings mixed with 8 kg of a straw based compost balancer. This gave a compost mixture with a balanced C/N ratio of 22 and a moisture content of 62 %. For comparison, a 300 1 capacity plastic compost bin containing 40 kg grass clippings mixed with 8 kg straw based compost balancer was set up at the same time. The temperature of each compost was recorded at regular intervals : The graph shows that the mesh cylinder composting container (according to the present invention) produced a higher peak temperature than the traditional plastic compost bin. In addition, this peak temperature was maintained for a longer time period. This was due to the mesh cylinder composter maintaining a more aerobic environment within the mass of composting material.