GB2225693A - Seeding system - Google Patents

Abstract

A sandwich seed mat comprises two sheets of cheesecloth, between which grass seeds are embedded in a matrix of dried starch paste. The dry sandwich is stiff, but thin (being virtually no thicker than the seeds) making it easy to handle. When the sandwich becomes wet, upon laying out on the ground, it goes limp. The paste gradually dissolves, as the grass seeds are germinating. The roots and shoots of the seedlings are well protected physically, and nurtured by the warmth and moisture retained by the cheesecloth and paste. The roots and shoots develop strongly and reliably because the roots and shoots are able to penetrate the cheesecloth without constraint while the cheesecloth remains intact, and holds the seed firmly. The cheesecloth rots away completely within a few months. A manufacturing process is also disclosed, in which the paste and seeds are sprayed onto one of the sheets of cheesecloth. The wet sandwich is squeezed between rollers, and the paste is dried in a few seconds by hot air.

Description

SEEDING SYSTEM This invention relates to a system for applying seed to a body of soil. The invention is particularly applicable for use with the kinds of seeds, such as grass seed, which rest on the ground surface.

BACKGROUND TO THE INVENTION The conventional approach to grassing an area (the embankment for a highway for example) is to apply pre-grown turf or sod to the surface of the soil. This approach is reliable, in that the grass has a good probability of establishing itself, if kept well watered. Pre-grown turf is, however, expensive.

Another approach is to apply grass seed. Whilst the seed itself is cheap enough, the chances of success are much less than with turf. In fact, providing the care needed to protect and nurture the seeds successfully usually turns out to be a more expensive proposition than the pre-grown turf.

It is an aim of the invention: (a) that the seeds are physically protected against birds and against being washed away, or otherwise disturbed, in the critical period just prior to, and during, germination; (b) that, once germination has started, the growing seedlings are nurtured and protected; and (c) that, after the seedlings have become established, the system encourages the establishment of a sturdy root structure.

DESCRIPTION OF THE GENERAL FEATURES OF THE INVENTION In the invention, the seeds are embedded in an adhesive, and the seeds are secured by the adhesive between two sheets of cheesecloth or similar fabric. The adhesive used in the invention preferably is a starch-based paste, such as common flour-paste, for example.

Such an adhesive, when dry, is hard and brittle, and remains so more or less indefinitely if kept dry. When the adhesive is exposed to moisture, however, it becomes limp, and starts to dissolve: when exposed to moisture, one of the features of flour-paste is that it first becomes gel-like, and then gradually dissolves. This tendency to predominantly-gradual disintegration of the paste applies over quite a wide range of exposures to moisture or wetness.

This property is made use of in the invention.

Proposals have been made in the past for mounting grass seeds on a fabric or paper carrier or mat. The idea was that the seed mat was applied to the ground surface, and water applied The carrier then disintegrated, depositing the seeds on the ground.

It is recognized in the invention that the seeds need rather more protection, especially during the critical germination phase, than has been provided for them in the prior art proposals.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION By way of further explanation of the invention, exemplary embodiments of the invention will now be described with reference to the accompanying drawings, in which: Fig 1 is a diagram showing apparatus and a process for manufacturing a seed mat sandwich; Fig 2 is a pictorial view of a sandwich as manufactured according to Fig 1; Fig 3 is a view corresponding to Fig 2 of a modified sandwich; and Fig 4 is a pictorial view of strips of the sandwich being arranged on the ground.

The seed mat sandwiches shown in the accompanying drawings and described below are examples which embody the invention.

It should be noted that the scope of the invention is defined by the accompanying claims, and not necessarily by features of specific embodiments.

The components of the apparatus 20 shown in Fig 1 may be described as follows. A first strip 21 of cheesecloth from a roll 23 travels along a table 25. At a paste-applying station 27, a spray bar 28 extends across the width of the strip 21, and paste 29 from a container 30 is pumped through the spray bar 28 onto the strip 27.

At a seed-applying station 32, grass seed 34 from a hopper 36 falls onto the strip 21, as the strip moves past along the table 25, below the hopper.

A second strip 38 of cheesecloth is fed from a roll 40 on top of the seed and paste that have been applied to the first strip 21. Together, the two strips 21,38 with the paste 29 and seeds 34, pass to a pressure station 41, where they are compressed by a roller 43 into a tight sandwich 45.

At the pressure station, the wet paste is squeezed well into the pores of the cheesecloth, and around and between the seeds. Excess wet paste is squeezed out, and drains away.

The wet sandwich 45 passes through a drying station 47, at while t air is blown onto and through the sandwich, causing the paste to dry out and become hard. The sandwich takes 10 or 15 seconds to pass through the drying station.

The dry sandwich 49 that emerges from the drying station 47 is collected on a take-up roll 50. The finished product may be expected to remain viable almost indefinitely, if well dried, and hermeticaly sealed.

The mechanisms for controlling the volume of the paste spray, the density of the grass seed, the speed of the strip, the rate of drying, and so on, are all conventional, and need not be described in detail Fig 2 shows a portion of the finished sandwich 52. The dried paste 29 is somewhat translucent, so that the seeds 34 embedded in the paste between the two sheets of cheesecloth 21,38 may, as shown, be observed by eye. The density of the seeds that is shown in Fig 2 may be expected to give good results usually, but particular climatic conditions may suggest other densities.

In the embodiment shown in Fig 3, a weighting stripe 54 is incorporated into the sandwich. The stripe 54 comprises a layer of filler material, which is inserted, during manufacture of the sandwich, between the two sheets 21,38 of cheesecloth. The material may be of the kind known as Envirosoft (Trademark) which comprises basically an inert organic filler (made from sewage sludge) of the kind used to provide bulk in fertilizers. The seeds can be allowed to be present also in the stripe 54.

The weighting stripe acts to help the sandwich to hold itself down onto the surface of the ground, at least at first: as the paste absorbes moisture it becomes limp and sinks down into intimate contact with the soil. Cheesecloth is the kind of material that tends in any case to attach itself to the ground (as it does to any rough surface) but it can happen that the edges of the sheet might tend to lift during the critical germination phase, if the sandwich is disturbed by windy weather for example, and the presence of the weighting stripe, when placed along the edges, can help in this regard.

In Fig 4, a roll 56 of the sandwich is positioned at the top of an embankment, and the sandwich is simply unrolled and laid in place. The sandwich may be cut with scissors or shears. Pegs 58 may be used if necessary to hold the sandwich in place. The edges of the individual strips of the sandwich should be overlapped at their edges, to ensure that no gaps appear between the strips. Any slight tendency for extra growth due to the overlap would soon correct itself.

When the sandwich has been applied to the ground1 it becomes moist, either due to rain , or dew, or to moisture in the soil. In fact, the presence of the sandwich, over the soil, in itself causes moisture to appear between the soil and the sandwich. In the invention, it is generally not necessary to water the soil, neither before applying the sandwich to the soil, nor as the seeds start to germinate.

Of course, grass seeds will germinate more reliably if sown in the moist conditions of spring or autumn, rather than during a summer drought.

It may be noted that the use of pre-grown turf requires, unlike the invention, the application of copious quantities of water to the just-laid turf. Also, in the conventional methods of applying grass seed itself, it has usually also been found necessary to water the soil. Not only is the watering operation expensive in itself, but the water turns the ground into a quagmire, so that both sodding and seeding are characterized by landscape workers as muddy, messy, operations.

By contrast, the invention permits the seeds, when protected by the sandwich, to germinate with just the minimum quantity of moisture being present -- the kind of quantity which is usually present in soil in spring and autumn.

Thus the sandwich of the invention may be laid whilst bone-dry, on soil which has not been watered.

The paste used in the invention tends to soften and become limp as it absorbs moisture, and consequently it is not necessary that the sandwich be soaked in water to soften the paste. The sandwich soon tends to sink down and to lie intimately flat against the surface of the ground.

The seeds do not start to germinate until the sandwich is wet enough for germination, by which time the sandwich is also wet enough and limp enough to have sunk down into full contact with the ground.

The paste 29 should be of the kind which readily absorbs moisture, and which goes limp upon becoming moist. An example of the kind of paste that is suitable for use in the invention is that sold under the product designation V0077, by Industrial Adhesives Ltd, of Toronto, Canada.

On the other hand, it should not be considered that the invention imposes stringent requirements as to the kind of adhesive: the invention requires merely that the adhesive is able to soften upon becoming moist, and that it is able to dissolve and degrade substantially completely. Not only flour-paste, but some animal-based adhesives also would suffice: many modern oil-based adhesives however tend not to be water-soluble, nor biodegradable, and are therefore unsuitable.

The cheesecloth used in the exemplary embodiment described above is the conventional loosely woven fabric of that name, which is made of cotton. The cotton filaments are about 0.1 mm thick. The filaments are spaced roughly 1.2 mm apart.

In cheesecloth, the filaments usually are woven, but the filaments may alternatively be knitted.

It should be noted that the cheesecloth is being used, in the invention, to supply physical support to the seeds at the critical phase of germination: therefore a non-woven material, or other material which might disintegrate when the paste dissolves, would not be suitable for use with the invention.

The fabric used in the invention may be made of other fibres, or mixtures of fibres, besides cotton, with the proviso that the fibres must, like cheesecloth, be degradable (virtually to nothing) over a period of a few months.

Other materials which would be suitable for use with the invention include muslin or butter-muslin, and gauze or bandage material.

One advantage which conventional cotton cheesecloth does have, which is useful for the invention, is that the material is very prone to snagging: thus the bottom layer of the sandwich readily snags on any slight protrusions in the soil or ground, which holds the sandwich steady; and, even green he paste has dissolved, virtually all the seeds remain snagged and held securely between the two sheets. The sheets of cheesecloth also hold themselves together, at any points of contact between the seeds. Also, cheesecloth is an inexpensive, easy to obtain, material.

DISCUSSION OF OTHER FEATURES OF THE INVENTION In the invention, the adhesive or paste layer may be thin: in fact, the thickness of the sandwich may be hardly more than the thickness of the seeds. Such a thin layer of adhesive, even when dried hard and brittle, imparts some slight stiffness to the sandwich, but the sandwich is quite flexible enough to be wound onto a roll. The sandwich may be bent further, or straightened out, without damage, except for a slight cracking of the dried paste. Even if the paste becomes cracked, the sandwich still holds together perfectly well, because of the binding effect provided by the cheesecloth. Thus, to apply the sandwich to the ground, the sandwich is simply unrolled and laid out upon the surface of the ground, and the sandwich may follow the curves and contours etc of the ground.

The fact that the sandwich is stiff whilst it is being laid out might at first be considered a disadvantage: but in fact he stiffness makes the material easier to handle. If the material were very floppy (as cheesecloth by itself would be for example) the task of laying out the sheet would be considerably more difficult, and would require more landscape workers. The inherent stiffness of the dry sandwich means that the individual strips of the sandwich may be quite wide (up to 2 metres or more) yet still easy to handle.

This is not to say that just any degree of stiffness in the dry sandwich would be acceptable. It is recognized that the thickness of paste produced by the manufacturing process as described is adequate not only to retain just the right amount of moisture to nurture the germinating seedlings, but is adequate also to provide just the right degree of stiffness in the sandwich to make the sandwich easy to handle.

Thus, the sandwich as described is stiff at first, ie immediately it is laid, and may be expected, at that time, to stand clear of the ground in some places. However, by the time the paste in the sandwich has absorbed enough moisture for the seeds to start to germinate, that quantity of moisture is enough to make the paste go limp. Grass seeds need a few days of being moist in order to germinate.

Therefore, by the time germination is established, and roots start to appear, the sandwich has become quite limp, and has settled into close contact with the soil; and it is an easy matter for the roots then to go straight down into the soil, without having to bridge an air gap.

It is important that grass Cie grass generally) does not become thatched , a condition in which the roots tend to congregate and form an impermeable layer in the upper 2 cm or so of the soil. The condition exacerbates itself: the shallow roots use up whatever oxygen and water is available, and the deeper roots gradually wither, leaving the roots vulnerable to attack from eg insects, bacteria, or a dry spell, etc.

It might be considered that the invention would promote thatching, in that the emerging roots would tend to spread horizontally along the undersurface of the sandwich, and that because, in the invention, the cheesecloth remains structurally-present for a long period, ie throughout the period of several weeks as the root system is becoming established, therefore thatching would have a tendency to occur. It might be considered that root development would be more certain and more robust with some of the prior art seed mats, wherein the mat material disintegrates before the root system starts to become established.

However, this is not so. In the invention, the cheesecloth acts as a matrix to hold the delicate emerging roots steady, and provides a protected environment whereby the roots can gain an entry into the soil at the most favourable point.

Grass roots need to spread horizontally in any case, and a thin layer of horizontally-extending roots serves to retain warmth and moisture.

In many previous systems which used a seed mat, the foundation fabric or material of the mat was required to disintegrate away before the roots could gain access to the soil. When the foundation material was paper, for example, the emerging roots could not easily penetrate the paper material. It was therefore critical in such systems that the paper should disintegrate either before, or in unison with, the emergence of the roots: if the paper disintegrated too soon, the seeds were left unprotected at the vulnerable just-germinating stage; if the paper disintegrated too late, the roots then in that case would tend towards thatching, because downward penetration was to some extent resisted.

And, inevitably, the disintegratable, zero wet-strength, material would disintegrate unevenly over its area, with the result that development of the seedlings was rather patchy.

Thatching is a problem normally associated with oldestablished grass, and the invention keeps it so, unlike the earlier systems which tended to promote thatching, which followed because the foundation material was impenetrable until it disintegrated.

In the invention, the development of the seedlings does not depend upon a change in the character or state of the fabric. In the invention, the fabric remains even and unaltered throughout the germination process. Traces of rotted cheesecloth can be expected to be found in the (established) grass even after, say, 12 months. Such traces can easily be pulled out by hand, if noticeable.

In the prior systems, it may be regarded that so long as the foundation material of the mat was present and intact, it interfered with root development; if not intact, the seeds were left unprotected. In the invention, the corresponding foundation material (ie the cheesecloth) is present throughout germination and root establishment, but yet the foundation material offers no barrier to downward development of the roots -- nor, indeed, to upward development of the shoots.

In the invention, both the paste and the cheesecloth tend to attract and retain moisture, and also warmth. The paste and the cheesecloth combine together to provide a protective blanket, and in effect to provide a tiny greenhouse in which the seeds are supplied with warmth and moisture. The cheesecloth may be a dark colour (preferably green obviously) to assist in heat absorption. The paste serves to keep each seed wet and warm while the seed is embedded in the paste. By the time the seed has started to germinate, the paste is at least fully softened, and may have started to disappear, so that the paste provides no physical barrier to the development of the seedling.

In the invention, the rate at which the paste softens and dissolves cannot be expected to take place evenly over the whole area of the sandwich: some seedlings will germinate while surrounded by paste, and others will germinate when the paste has almost gone. It has been found that this does not cause patchiness: the moisture-retention and protection effect of the cheesecloth itself, even when the paste is almost gone, is adequate to nurture the seedlings.

As far as physical retention of the seeds is concerned, the following point may be noted. Two sheets of dry cheesecloth, when placed together, do snag slightly to each other: but two sheets of wet cheesecloth, even if they later dry out, are virtually impossible to separate. The fibres tend to intermingle and lock together. Thus, even when the paste is gone, the seed is locked very securely in position -- and yet, it may be noted, at the same time the seed is directly open to air circulation, moisture, and sunlight.

In any case, in the invention, the presence of the cheesecloth serves very well to prevent the paste, when in a wet gel condition, from washing away. Thus, the paste may be expected to remain present for a considerable period.

It is essential, in the invention, that both sheets of fabric be present in the sandwich.

The shoots and roots can grow through the large, wide-open, "pores" of the cheesecloth without being restricted in any way The alath serves to physically retain the seedlings, against movement, which, if it took place, would disturb the just-emerging seedlings.

When the sandwich has been laid upon the ground, and has settled into intimate contact with the soil, the seeds are held in place, once the paste has disappeared, by being snagged and trapped between the two layers of cheesecloth.

It might be considered that the paste is therefore not necessary. However, the virtually ideal conditions for seed development which is achieved by the sandwich may be attributed to the combination of the paste with the cheescloth: each element of the sandwich on its own would not have the same overall effectiveness during germination.

Besides that, the paste is necessary to ensure that the sandwich remains a unitary structure during transport and handling of the sandwich. Without the paste to hold the sheets together during the rough-handling associated with transport and laying-out, inevitably the cheesecloth sheets would separate at some points, creating pockets, and allowing the seeds to move out of position. And if the sheets were to separate along the edges, the seeds would fall out.

The seeds are embedded in the dry, brittle, paste, between the two sheets of cheesecloth. If only one sheet of cheesecloth were provided, then, as the paste cracked during handling, many of the seeds would fall off. Also, just a single sheet of cheesecloth would not hold the moisture so well, nor provide physical protection.

The sandwich mat of the invention serves to protect the seeds against physical disturbance. When the sandwich has just been laid, and is still stiff1 a landscape worker may step on the sandwich without causing any damage, and without the seeds adhering to his footwear. Similarly, an animal may walk over the sandwich without causing damage. Birds are, normally, a great danger to grass seed, but the invention provides almost complete protection against birds.

Even when the paste has become limp, and started to dissolve, treading on the sandwich would, within limits, still not be expected to interfere with seed development.

It is important that a seedling, at the critical period of root-establishment, not be disturbed physically. The invention is very good at holding the seeds perfectly still relative to the ground at this critical phase. The limp cheescloth settles down into close contact with the ground, such that each seed, over the whole area of the sandwich, is either at, or only a short distance away from, a point where the cheesecloth is snagged quite firmly to the soil. Even if heavy showers should take place during germination, the developing seedlings may be expected to remain in place. Of course, rain will disturb the sandwich and seedlings if heavy enn but the sandwich of the invention may be expected to hold the seedlings steady, and firmly in place, for longer and to a greater extent than previous mats or other seeding techniques.In fact, the presence of the sandwich can serve to hold the soil against erosion to some extent.

It would be possible, in the invention, to include chemical or other additives within the adhesive. However, this is not normally necessary. Most fertilisers for grass, for example, tend to work by promoting short-term green growth at the expense of deep root development, and are not required for germination. Bird and animal repellents are not needed in the invention, as mentioned. Insect repellents are also not needed: insect pests in grass generally attack established roots, and it is, if anything, an advantage to have insects present during seedling development.

The only outside" assistance a germinating grass seedling needs is from a warm moist environment, and from protection against physical disturbance. The paste/cheesecloth sandwich as described is able to provide this, without other additives. It might sometimes be advantageous to mix some peat with the paste for added water retention, but that would also add to the thickness of the sandwich, and is usually not necessary.

As described, the sandwich may be used to grass an embankment, or other prepared area, where the soil is bare, and may be raked, for easy root development. Alternatively, the sandwich may be used to repair bare patches in lawns, where its ability to be cut to shape with scissors is an advantage.

Another application is in the repair of sports pitches.

Here, the sandwich may be laid out over the (raked) ground: if the still-remaining grass grows through the sandwich, that is acceptable; if it dies, it serves as a repository of moisture and warmth for the new growth, As described, the invention is particularly useful for grass seed, grass seed being one of those types of seed which is laid out upon the surface of the ground. The invention may however also be used with seeds, such as annual flower seeds, which are buried in the soil. Here, the sandwich mat of the invention, with the appropriate seeds embedded in it, would be laid out in a trench or other place, and covered over with a suitable depth of soil. This may be done indoors in a nursery or glasshouse for example, or outdoors in the gound.

However, one of the main advantages of the invention lies in the fact that the sandwich is suitable for use in the much more demanding conditons at the exposed outdoor groundsurface. The sandwich of the invention provides physical protection, which is simply not needed by seeds below ground. Similarly, the required envelopment of the seed in moisture is automatically provided when the seeds are below ground. On the other hand, the sandwich of the invention is, as described, so simple to make, and is so easy and convenient to handle, to transport, and to set in place, even by relatively unskilled gardeners, as to promote its use for seeds that are to be buried.

Claims (8)

1. CLAIM 1. A seed mat sandwich, wherein:

   the sandwich includes first and second sheets of fabric; the fabric is cheese-cloth, or the like, comprising very loosely woven or knitted filaments of degradable cotton, or cotton-like material; the two sheets are disposed with respective surfaces thereof facing one upon the other; the sandwich includes an adhesive; the adhesive is located between the sheets, and is so disposed and adapted as to hold the sheets together; the adhesive extends in a body, substantially without interruption over the whole area of the said facing surfaces; the adhesive has the form of paste, which has dried out to a hard, brittle consistency; the adhesive is of the kind which becomes limp upon becoming moist, and which substantially completely dissolves in water; the sazdwion nindes seeds, and the seeds are located as a layer of seeds between the two sheets; and the seeds are embedded, substantially completely, in the body of adhesive.
2. CLAIM 2. Sandwich of claim 1, wherein the filaments that make up the fabric are approximately 0.1 mm in diameter, and are set at a pitch of approximately 1.2 mm.
3. CLAIM 3. Sandwich of claim 1, wherein the seeds are grass seeds.
4. CLAIM 4. Sandwich of claim 1, wherein the adhesive is flour paste.
5. CLAIM 5. Sandwich of claim 2, wherein the fabric is cheesecloth.
6. CLAIM 6. Sandwich of claim 1, wherein the sandwich includes a body of heavy material, said material being organically inert, the material being located between the two sheets, and embedded in the body of adhesive, the material occupying only occasional spaced apart locations of the said whole area of the facing surfaces.
7. CLAIM 7. A procedure for applying grass seed to soil, and for promoting the germination and subsequent growth of grass, comprising the steps: of providing the seed mat sandwich of claim 3; of laying the sandwich out directly upon the surface of the soil; and of leaving the sandwich substantially uncovered during the subsequent period of germination of the grass seeds.
8. CLAIM 8. Procedure of claim 7, including the further step of pegging the sandwich to the ground.