GB2326579A

GB2326579A - Water retention system for horticultural use

Info

Publication number: GB2326579A
Application number: GB9713746A
Authority: GB
Inventors: Robert Salvage
Original assignee: B J EUROCHEM Ltd; FIELDS OF FRAGRANCE Ltd
Current assignee: B J EUROCHEM Ltd; FIELDS OF FRAGRANCE Ltd
Priority date: 1997-06-27
Filing date: 1997-06-27
Publication date: 1998-12-30
Also published as: GB9713746D0

Description

Water Retention System for Horticultural Uses.

The present invention relates to a water retention system for horticultural uses. In particular it relates to a system of particular benefit in container gardening, such as hanging baskets.

The main problem associated with container gardening is in providing enough water for the roots which are contained and thus prevented from seeking out water wherever they can. Water retaining granules of silica gel have been used mixed into the compost. Other substances which form gels when hydrated have been proposed.

However, it has been found that these materials take unacceptably long times to absorb water. Periods of up to an hour are recommended in most cases for maximum absorption of water. Clearly this is unacceptably long for containers of plants as water applied to the soil will have drained away long before maximum absorption could occur. Silica is not considered to be ideal for retention of water in compost as it is thought to bind water too strongly.

According to the present invention, in its broadest sense, there is provided a waterpermeable pouch or bag containing a water-retentive medium. Preferably the waterretentive medium is or is derived from a naturally occurring medium, such as vermiculite, preferably an exfoliated vermiculite, more preferably a fine grade vermiculite.

Preferably, the water-permeable pouch or bag is made from a heat-sealable fibrous paper. Preferably, the paper is of food grade. More preferably, the paper is of the type used for tea-bags. Preferably, the paper has an air permeability of around 80-90 m3min~lm-2 or more, and a wet burst strength of around 28 kPa.

Optionally, the water-permeable pouch may also contain a slow-release fertiliser composition.

The above and other aspects of the present invention will now be explained in further detail with reference to some examples.

Advantageous results have been achieved by making the water-permeable pouches of the present invention using a high quality paper made from cellulose and thermoplastic fibres. Such fibres are used in the manufacture of tea-bags and have been shown to withstand immersion in water for long periods of time without decay.

In particular, a grade of paper manufactured by J R Crompton Limited and sold under the name Superseal has been found to be particularly good. The manufacturer's tests have shown that pouches manufactured from their Superseal paper can withstand immersion in boiling water indefinitely. This is important to avoid decomposition of the pouch which could lead to its contents being washed out of the container. The J R Crompton Superseal paper has a weight of 26gum and an air permeability of 86 m'min-lm~2. It has a wet burst strength of 28kPa and can be sealed to a seal strength of 500 g/50mm.

The pouch can effectively contain any water-retentive material. Materials which do not bind water too strongly are preferred. Naturally occurring materials, or materials derived from such sources are to be preferred. Minerals such as vermiculite or Fuller's Earth are suitable examples. Excellent results have been achieved with s errniculite particularly exfoliated vermiculite such as that sold under the trade mark 'ermalite by Silvaperl of Gainsborough, Lincolnshire. It has been found that pouches containing vermiculite take up water upon contact, effectively absorbing their maximum volume of water instantaneously. This is particularly beneficial to avoid loss of water through run-off. Vermalite is sold in a range of grades (V0 - V3) based on particle size. Tests have been made to determine the preferred grade for use in the present invention. Three pouches were prepared using J R Crompton Superseal paper and containing 50g of VO, V1 and V2 grades. The bags were placed in a container of water an allowed to absorb as much water as possible over a period of time. The bags were then placed flat on a drainer and allowed to drain for 15 minutes. The bags were then weighed to determine the mass, and thus volume of water retained. The results are shown in Table 1.

Table 1

Manufacturer's GRADE Particle Size Mass of water retained after Absorbency Figures imm . . 15 minutes /g /litre per cubic metre Vo 0.01-1.0 560-610 270 V1 0.5-2.0 510-530 256 I V2 1.0-3.0 430950 264 Particle size is also relevant. In use, the pouches may be under a significant weight of soil or compost. A pouch containing vermiculite with a small particle size may be compressed excessively such that the vermiculite cannot, in fact, absorb its theoretical maximum volume of water. From the results of the test. it was determined that the grade V2 had the best balance between water absorbency, particle size and cost.

The water-retaining pouches of the present invention may be any size and contain any mass of water-absorbing material. However, it is expected that pouches of around 12cm x 8cm containing about 10-15 g of V2 grade Vermalite exfoliated Vermiculite.

will be generally suitable. The user then simply uses as many bags as necessary, preferably placing a ring of bags around the edge of the container and towards the bottom (to encourage root growth). For a small pot, a single pouch towards the bottom of the pot may suffice. Initial experiments have shown considerable improvements in the rate of growth of plants grown in pots using the water-retentive pouches of the present invention as against those grown in pots without, even when both pots are given exactly the same volume of water each day.

Claims

1. A horticultural water-retention system comprising a water-permeable pouch or bag containing a water-retentive medium.

2. A water-retention system as claimed in Claim 1 wherein the water-retentive medium in vermiculite.

3. A water-retention system as claimed in Claim 2 wherein the vermiculite has a mean particle size of 1 to 3mm.

4. A water-retention system as claimed in any one of Claims 1 to 3 wherein the water permeable pouch or bag is made from a heat-sealable fibrous paper.

5. A water-retention system as claimed in Claim 4 wherein the paper has an airpermeability of around 80-90 m3mirr1m-2 or more.

6. A water-retention system as claimed in any preceding claim wherein the bag or pouch also contains a slow-release fertiliser composition.

7. A horticultural water-retention system substantially as herein described.