WO1996027573A1

WO1996027573A1 - Time-release agricultural product and its use

Info

Publication number: WO1996027573A1
Application number: PCT/US1996/002990
Authority: WO
Inventors: Alberto Kling; Jorge Miller
Original assignee: Punto Quimica Ltda.; Idea, Inc.
Priority date: 1995-03-03
Filing date: 1996-03-04
Publication date: 1996-09-12
Also published as: AU5182596A

Abstract

By combining a systemic agricultural chemical with a hydrophilic gel or gel-forming material, a solid product is prepared which can be planted with seeds or placed on plant roots and then covered with earth. The use of these solid compositions provides application of the agricultural chemical over an extended period of time without having the agricultural chemical washed away from the site of application. By varying the molecular weight or proportion of the hydrophilic gel or gel-forming material, the period of time over which the agricultural chemical is available can be varied.

Description

TIME-RELEASE AGRICULTURAL PRODUCT AND ITS USE

Field of the Invention

Plant-treating material is placed in a form from which it is extracted over an extended period of time, which conserves active components and which reduces stream pollution by such components.

Background

Application of fertilizer and pesticide to crops and other plants entails considerable cost in labor and loss of expensive products, which are washed away by rain or irrigation, with concurrent stream pollution.

Summary of the Invention

A substantially water-soluble fertilizer, pesticide or other plant growth-, health-, proliferation- or development-enhancing substance is intimately admixed with a hydrophilic gel or gel- forming material to produce a product from which active components are extractable.

There are several different aspects to the subject invention. One aspect concerns agriculturally-acceptable products. Each of these is useful for enhancing growth, development, proliferation or health of plant life or for reducing, controlling or eliminating pests, such as insects, fungi and other parasites, that are apt to attack plant life. With regard to reducing, controlling or eliminating pests, the agriculturally-acceptable products are planted with seeds or on or near roots of plants; their mode of action is systemic, and they are transmitted from the root to the area in which they will be most effective.

The products comprise an intimate, preferably substantially homogeneous, admixture of at least one agriculturally-active component and a hydrophilic gel or a hydrophilic gel-forming material. The agriculturally-active component is preferably one which is suitable for serving one of the previously-noted activities. Examples of such components are well known to any artisan, and no specific active component is, per se, an essential part of the subject invention.

The hydrophilic gel or gel-forming material is preferably one which is biodegradable.

A further aspect of the invention is particularly directed to active components which tend to pollute streams. The subject compositions reduce or eliminate stream pollution by such components.

Another aspect of the invention is conservation of agriculturally-active components. The very nature of the compositions maintains the active components at a place where they will serve their intended purpose over an extended period of time. A still further aspect of the invention is thus providing extended-time-release dosage forms of the agriculturally-acceptable products.

An object of the invention is thus to provide a system whereby agriculturally-active components are encased within a gel structure in a quantity required for the life of a crop with a single application or, e.g. , for fruit trees or perennials for a desired time without having the active components leached by rain or irrigation.

A further object of the invention is to conserve active agricultural components. Another object of the invention is to reduce stream pollution by active agricultural components. Still further objects are apparent from the accompanying description.

Details

Active, substantially water-soluble agriculturally-active components are substantially uniformly admixed with a hydrophilic gel or gel-forming substance. The resulting admixture is formed into granules, spherules, tablets or other suitable solid.

The gel or gel-forming material is advantageously a cellulose ether or a pectin, but can be any other agriculturally- acceptable hydrophilic gel or gel-forming material. The preferred such material is sodium carboxymethylcellulose, which, like pectins, is available over a large range of molecular weights, which makes it particularly suitable for extending the time of active-component release for a large variety of predetermined lengths of time. The actual length of extended release time is also dependent upon the proportion of the gel or gel-forming material in the dosage forms employed. Other hydrophilic gels and gel-forming materials are known. Naturally, those which are biodegradable are preferred.

The agriculturally-active component of the compositions is fertilizer, pesticide, or other plant growth-, development-, proliferation- or health-enhancing substance. Such materials are well known.

The actual dosage form is that of virtually any unitary solid, e.g. , granule, spherule, or tablet. The means and methods for preparing appropriate compositions in granule, spherule or tablet form are state of the art and well known to those familiar with this technology.

To prepare compositions of this invention, desired or required components are admixed with a hydrophilic gel or a hydrophilic gel-forming substance, and the resulting admixture is tableted, granulated or formed into spherules by conventional techniques.

When the obtained unitary substantially homogeneous solid product is placed in water, it, being highly hydrophilic, starts absorbing water and forms a gel in which agriculturally-active components are encased. When the gel-forming material is a hydrophilic cellulose ether, e.g. sodium carboxymethylcellulose, the encompassing gel is transparent.

The rate of the fusion of agricultural chemical particles in the encompassing gel is readily calculatable, as by the following formula:

D² . RT S 3Nπry herein r is the ionic radius of the atom

N is Avogradro's number

y is the viscosity of the medium

D is the mean displacement of the ion

S is the unit time

R is gas constant

T is temperature (^°K)

Considering the displacement by diffusion of saturated solutions in water (viscosity is 1 cp.) and that the viscosity of a 1 percent solution of one type of sodium carboxymethcellulose is of the order of 5000 cps. , the rate of diffusion in that type of sodium carboxymethylcellulose will be 5000 times less that in water.

Since the tablet, sphere or other solid form contains practically solid gel or gel-forming material, e.g. cellulose ether, the viscosity at that level is practically infinite until enough water enters the solid, and diffusion can start slowly.

Water diffusion towards the solid meets a diluted gel of relatively low viscosity, and its rate of diffusion is high due to lower viscosity of the medium and to its small ionic radius. This inflow of water tends to push back ions with a higher radius, as predicted by the equation.

By "substantially water-soluble composition" is meant a composition from which active components, in the presence of water, are extractable by plant roots to a sufficient degree to enable active components thereof to be effective for their intended purpose. The gel or gel-forming material is made adaptable to time- release requirements by varying its molecular weight, its proportion and/or amount in any tablet or other solid-form agriculturally-acceptable product. Increasing the molecular weight increases the period of delay in release of active component. The gel or gel-forming material is designed to remain in place for substantially the same length of time as available active component remains in the dosage form applied.

The active component comprises one or any combination of active ingredients useful as systemic pesticides and/or for plant growth-, development-, health- or proliferation-enhancing.

EXAMPLE 1 A composition for tablets or spherules useful to provide minor elements required by palm trees every six months follows: Copper, as sulfate 0.52 gram

Zinc, as oxide 0.16 gram

Manganese, as sulfate 0.54 gram

Boron, as boric acid 1.59 grams

Each tablet contains the above ingredients plus

Citric acid 0.42 gram

Sodium carboxymethylcellulose 1.77 grams

A resulting tablet corresponds to a 6-month requirement for each plant. Earth is removed to expose a root and a tablet placed on top thereof, then covered with earth. As soon as rain or irrigation wets the tablet, it begins to swell, and diffusion starts.

If a tablet or spherule is dug out after one month and cut open, it is surrounded by many rootlets which have penetrated the gel to adsorb the elements the plant requires, penetrating only to a distance where the concentration is not toxic to the root.

After 6 months the tablet or sphere disappears completely, since cellulose ethers are biodegradable. In the case of tablets requiring a 6-month retention time, high viscosity sodium carboxymethylcellulose is recommended (viscosity of 1% solution, 5000 cps) . For potato plants, a 3- month retention time is achieved with sodium carboxymethylcellulose of lower viscosity (2000 cps of 1% solution) .

EXAMPLE 2 Fertilizer granule or spherule compositions useful for providing nitrogen, potassium and phosphorus, required by potato plants from planting to harvesting, follows:

Potasium Sulfate 100 parts by weight

Monocalcium Orthophosphate 100 parts by weight Ammonium Nitrate 150 parts by weight

Sodium Carboxymethylcellulose 350 parts by weight

The ingredients are mixed and pelletized to form 14 mm pellets, each weighing 2.0 grams. Seven or eight pellets (planted together with each potato seed) are sufficient for the NPK requirements for the crop.

EXAMPLE 3 A composition for tablets or spherules useful for providing a systemic fungicide required by banana trees to control fusarium follows:

Sodium formaldehyde sulfoxylate 1.25 parts by weight Sodium carboxymethylcellulose 2.5 parts by weight

The ingredients are mixed and tabletted (each tablet weighing 5 grams) . Use of these tablets eradicates fungi from banana trees. If, after 2 months, the trees are again invaded, another tablet is used, again uncovering a root (where the tablet is placed) and then covering the tablet with earth. EXAMPLE 4 A composition for tablets or spherules useful for providing a systemic nematocide required by banana trees to control nematodes follows:

Sodium acrolein sulfoxylate 1.25 parts by weight Sodium carboxymethylcellulose 2.5 parts by weight

The ingredients are mixed and tabletted (each tablet weighing 5 grams) . Use of these tablets eradicates nematodes from banana trees. If, after 2 months, the trees are again invaded, another tablet is used, again uncovering a root (where the tablet is placed) and then covering the tablet with earth.

There are many variations possible to obtain desired retention times, for instance smaller tablets, granules or screened particles or a smaller proportion of gel or gel-forming material; also, variations of viscosity of the cellulose ethers or other gel-forming material employed. The optimum for each crop is readily determined. Fertilizers, systemic fungicides and insecticides and other agricultural chemicals are applied with this system.

Granules can be applied simultaneously with seeds. The economy in labor and waste of fertilizers is considerable. Pollution of fertilizers running into streams is prevented.

The invention and its advantages are readily understood from the preceding description. Various changes may be made in the method or products without departing from the spirit and scope of the invention or sacrificing its material advantages. The process and products hereinbefore described are merely illustrative of preferred embodiments of the invention.

Claims

WHAT IS CLAIMED IS:

1. An extended-time-release agriculturally-acceptable product which comprises a) a solid, substantially water-soluble composition in intimate admixture with b) a hydrophilic gel or gel-forming material, wherein the substantially water-soluble composition is a pesticide or plant growth-, development-, health- or proliferation-enhancing substance.

2. A dry product of claim 1 in granule, spherule or tablet form.

3. A dry product of claim 1 wherein the gel or gel-forming material is a cellulose ether.

4. A dry product of claim 1 wherein the gel or gel-forming material is a pectin.

5. A dry product of claim 1 wherein the gel or gel-forming material is biodegradable.

6. A dry product of claim 1 wherein the gel or gel-forming material is adaptable to time-release requirements.

7. A dry product of claim 1 wherein the substantially water-soluble composition is a fertilizer.

8. A dry product of claim 1 wherein the substantially water-soluble composition is a systemic fungicide.

9. A dry product of claim 1 wherein the substantially water-soluble composition is a systemic insecticide.

10. A method of conserving an agriculturally-acceptable plant-treating composition and/or reducing stream pollution by such composition, which comprises applying the composition, in the form of a product of claim 2, directly to a seed, close to or on a root of a plant, or planting said composition with a seed.

11. A method of claim 10 wherein the composition is a fertilizer.

12. A method of claim 10 wherein the composition is a systemic fungicide.

13. A method of claim 10 wherein the composition is a systemic insecticide.

14. An extended-time-release substantially homogeneous admixture which consists essentially of an agriculturally-active component and a hydrophilic gel or hydrophilic gel-forming material in unitary solid dosage form, and wherein the agriculturally-active component is at least partially water soluble.

15. An admixture of claim 14 wherein the agriculturally- active component comprises fertilizer.

16. A method of fertilizing a plant which comprises applying a product of claim 15 directly to a plant root or to soil in the immediate vicinity thereof.

17. An admixture of claim 14 wherein the agriculturally- active component comprises systemic fungicide.

18. A method of preventing fungi from infesting a plant or of combatting fungi infesting a plant which comprises applying a product of claim 17 directly to a root of the plant, and covering the product and root with soil.

19. An admixture of claim 14 wherein the agriculturally- active component comprises systemic insecticide.

20. A method of preventing or combatting insect infestation of a plant which comprises applying a product of claim 19 directly to a root of the plant, and covering the product and root with soil.

21. A solid product of claim 1 wherein (a) and (b) are the sole essential components and (b) is water soluble.