WO1992019095A1

WO1992019095A1 - Plant growing matrix

Info

Publication number: WO1992019095A1
Application number: PCT/US1992/003746
Authority: WO
Inventors: Tollie Ross Green; George Wyatt Prejean; Timothy Claud Sharp
Original assignee: E.I. Du Pont De Nemours And Company
Priority date: 1991-05-09
Filing date: 1992-05-06
Publication date: 1992-11-12

Abstract

A water-rententive matrix composition for growing plants. The composition comprises from about 50 % to about 99 % by dry weight of a bulking agent and from about 1 % to about 25 % by dry weight of a water-retentive polymer having a water absorbency of between 50 and 600 times its weight. The bulking agent includes at least 2 % by dry weight composted rice hulls. Optional components of the composition include a water-soluble binding agent, a nonionic surfactant and/or one or more additives such as pesticides and nutrients. The composition is compressed into articles such as chip-like wafers to simplify shipment, storage and use thereof.

Description

developed in part by the Applicants hereof which

includes 55% to 80% by dry wt. of a hydrophilic fibrous bulking agent (e.g., peat), about 0.001% to 0.35% by dry wt. of a nonionic surfactant (e.g., polyoxypropylene-polyoxyethylen black copolymer), about 0% to 40% by dry wt. of a water soluble binding agent (e.g., poly (vinyl alcohol), about 10% to 25% by wt. water and about 5% to 20% by dry wt. of a water-retentive polymer having a water absorbency of between 50 and 600 times its weight (e.g., potassium acrylite acrylamide copolymer).

Applicants previously filed an application to this composition (PCT US90/04816, published 21 March 1991).

When used as a conventional potting soil substitute, the matrix of PCT US90/04816 absorbs and retains water and subsequently releases the water to embedded plants over time on an as-needed basis. The matrix can be compressed into articles such as chip-like wafers allowing it to be easily shipped, stored and used.

The use of rice hull ash in conjunction with water swellable binders or polymers was disclosed in U.S.

Patent No. 4,707,176. However, this disclosure

requires that the rice hull ash be in an amphorous state.

SUMMARY OF THE INVENTION

In accordance with the present invention, a water-retentive matrix composition for growing plants is provided. The composition comprises in the range of from about 50% to about 99% by dry weight, based on the total dry weight of the composition, of a bulking agent, the bulking agent including at least 2% by dry weight, based on the total dry weight of the composition, composted rice hulls, and in the range of from about 1% to about 25% by dry weight, based on the total dry weight of the composition, of a water-retentive polymer having a water absorbency of between 60 and 600 times TITLE

PLANT GROWING MATRIX

FIELD OF THE INVENTION

This invention relates generally to matrix

compositions for growing plants, and more particularly, but not by way of limitation, to water-retentive matrices useful as substitutes for conventional potting soil and for encapsulating seeds.

BACKGROUND OF THE INVENTION

Conventional potting soil and related compositions are used throughout the world in many commercial and domestic applications. For example, such compositions are used as matrices for growing and supporting house plants, as matrices for germinating seeds and nurturing seedlings for future transplantation and as soil conditioners for gardening purposes. The popularity of ornamental house plants and outdoor trees and shrubs, as well as the corresponding market for seedlings of such plants ready for transplantation, are increasing.

Unfortunately, there are many problems and

difficulties associated with nurturing and transplanting seedlings and growing and replanting plants. Due to their bulk and weights, conventional potting soil compositions can be difficult to ship, store and use.

Proper nurturing of potted seedlings and maintenance of mature plants require attentive watering, often at specific and frequent intervals. Failure to properly water a plant can cause a plant to suffer reduced growth, wilt and even die.

It has been known for some time that seeds can be encapsulated or covered with a matrix material to protect the seeds against injury and enhance conditions favorable for germination and subsequent plant growth. An improved seed encapsulating matrix has recently been its weight. Depending on the application in which it is to be used, the composition can optionally include a water-soluble binding agent, a nonionic surfactant, a small amount of water and/or one or more additives such as pesticides, fertilizers, plant hormones or other additives leading to specific end-use applications . The composition is very suitable for compression into chip-like wafers or other articles of various shapes and sizes.

The inventive composition is particularly useful as a substitute for conventional potting soil in

transplanting and replanting applications. The ability of the composition to be compressed into articles of various shapes and sizes allows it to be easily shipped, stored, marketed and used. Compressed articles formed of the composition are substantially denser and less bulky than the equivalent usable amount of conventional potting soil. Upon addition of water, the compressed articles rapidly break apart and expand to form a material that can substitute for conventional potting soil. The labor associated with maintaining (e.g., watering and feeding) plants grown in the composition is much less than the labor associated with maintaining plants in conventional potting soil. For example, after a seedling transplanted in the inventive composition is initially watered, it typically requires less frequent watering than a plant grown in conventional potting soil. The invention has application in the fields of forestry, agronomy and commercial and amateur

horticulture.

The inventive composition out performs the

composition of PCT US90/04816 as a conventional potting soil substitute. The primary advantage of the instant inventive composition results from the use of composted rice hulls as part of the bulking agent. The composted rice hulls cause an unexpected, synergistic wicking or capillary action, i.e., an uptake of fluid into the composition. The improved capillary action results in faster water absorption or wettability without a separately added surfactant, greater water retention or holding power, and a greater pot volume of end product. The characteristic of faster water absorption is believed to enhance the marketability of the product. The inventive composition does not require the addition of a separate nonionic surfactant. The elimination of a separately added surfactant simplifies the production of the invention and eliminates the risk to production workers of possible surfactant-related injury.

It is, therefore, an object of the present invention to provide a matrix composition that effectively serves as a substitute for conventional potting soil and overcomes many of the difficulties associated therewith.

It is an object of the invention to provide such a composition that can be compressed into articles of various shapes and sizes allowing it to be easily shipped, stored, marketed and used.

It is an object of the invention to provide such a composition that rapidly absorbs and retains a large volume of water and subsequently releases the water to plants as needed thereby.

Further objects of the invention are to provide a matrix composition that is useful as an encapsulating or cover material for seeds to protect the seeds and enhance conditions favorable for germination thereof, and that will protect subsequent seedlings during transplantation thereof.

Numerous other objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon reading of the following

disclosure including the examples provided therewith. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In one aspect, the present invention is a water-retentive matrix composition for growing plants. In another aspect, the invention is an article of

manufacture such as a chip-like wafer formed of the inventive composition. Other aspects of the invention include methods of forming the inventive composition and articles of manufacture thereof and methods of utilizing the inventive composition in connection with

transplanting, replanting and growing plants and

germinating seeds.

As used herein including the appended claims, the term "plant" means any member of the vegetative group of living organisms (e.g., vegetables, flowers, house plants, shrubs and trees). The phrase "percent by dry weight, based on the total dry weight of ..." means the percent by weight of the reference component in dry form (i.e., approximately zero weight percent water), based on the total weight of the composition (or bulking agent, etc.) in dry form (i.e., approximately zero weight percent water). "Peat" means partially

carbonized vegetable tissue formed by partial

decomposition in water of various plants (as mosses of the genus Sphagnum). "Composted" means converted to a mixture of largely decayed organic matter.

The inventive matrix composition comprises (a) in the range of from about 50% to about 99% by dry weight, based on the total dry weigh of the composition, of a bulking agent, the bulking agent including at least 2% by dry weight, based on the total dry weight of the composition, composted rice hulls; and (b) in the range of from about 1% to about 25% by dry weight, based on the total dry weight of the composition, of a water-retentive polymer having a water absorbency between 50 and 600 times its weight. Water is rapidly absorbed and retained by the composition when added thereto. The composition rapidly expands upon water absorption to form a material that is a suitable substitute for conventional potting soil.

The problem to be solved by this invention is to provide a suitable potting medium composition that can be shaped into an article which additionally satisfies requirements for forming the compressed wafer and accounts for the conditions the wafers would be

subjected to during use. Therefore, Applicants prefer the following composition for the general in-home horticultural application:

- Bulking agent: 82-91% peat 72-78% composted rice hulls 10-13%

- Water-retentive polymer 11-13%

(Stockosorb 300Z - crosslinked potassium acylate acylamide copolymer)

The composition is made by drying peat to between 25% and 15% moisture content and drying rice hulls to between 5-15% moisture content. The peat and rice hulls are blended with the water retentive polymer for 15-20 minutes. The blended material is stamped into wafers (2.5" × .5") with at least 20 tons of pressure. It is understood that demands of outdoor applications, varying plants and shade and humidity conditions may drive alterations in the proportions of composition elements.

The Bulking Agent

The bulking agent forms a major portion of the composition. It draws fluid into the composition by wicking or capillary action. It also provides pore space and loft to the composition thereby increasing the pot volume of the end product obtained upon water absorption. The pore space allows gas (e.g., oxygen) to be exchanged between a seed or plant embedded in the composition and the surrounding environment. The material also provides support for the root system and the plant.

The exact amount of the bulking agent that should be employed in the composition depends on the application intended for the composition. For example, for use with plants grown under shade cloth, a greater percentage of bulking agent is called for. Preferably, the bulking agent is present in the the composition in an amount from about 50% to about 99%, more preferably from about 80% to about 90%, by dry weight based on the total dry weight of the composition. Most preferably, the bulking agent is present in the composition in an amount of about 85-88% by dry weight based on the total dry weight of the composition.

The bulking agent preferably comprises from about 5% to about 50% by dry weight composted rice hulls and from about 94% to about 50% by dry weight of at least one material selected from the group consisting of peat, tree bark, processed bark ash, composted pine bark, steam fractionated pine bark, paper pulp, kelp meal and other similar bulking agents, the above weight percents being based on the total dry weight of the composition. The material selected from the group consisting of tree bark, processed bark ash, composted pine bark, steam fractionated pine bark, paper pulp, kelp meal and other similar bulking agents, and peat is preferably peat. The bulking agent more preferably comprises from about 10% to about 30% by dry weight composted rice hulls and from about 60% to about 90% by dry weight peat, most preferably from about 10% to about 20% by dry weight composted rice hulls and from about 65% to about 80% by dry weight peat, the above weight percents being based on the total dry weight of the composition. As used herein and in the appended claims,

"composted rice hulls" are rice hulls that have been subjected to composting, i.e., biological degradation. The composted rice hulls have been composted by and are obtainable from the Butler Rice Hull Compost Co., P.O. Box 933, North Little Rock, AR 72115-0933. Use of composted rice hulls is important because of their wicking and wetting capacity which eliminates the need for a separately added surfactant, increased wettability over peat alone, superior water holding capabilities and decreased water loss from evaporation as compared to peat alone. Rice hull ash is not included in the meaning of composted rice hulls.

Use of the rice hulls makes the bulking agent sufficiently hydrophilic. Surprisingly, the composted rice hulls cause the bulking agent to have a

synergistic, greater wicking or capillary action than it has when formed of other materials such as peat, alone or combined. The greater capillary action causes the composition to achieve faster water absorption, greater water retention or holding power and a greater volume of end product upon water absorption. The greater volume of water retained significantly decreases the frequency of required watering and feeding. One aspect of the invention will use 100% by dry weight composted rice hulls as the bulking agent.

The Water-Retentive Polymer

The water-retentive polymer, referred to in the art as a super absorbing polymer (SAP), functions to absorb and retain water when water is added to the composition and to release the water to a seed or a plant embedded in the composition on an "as-needed" basis. It also functions to expand the volume of the composition and to provide pore space. The water-retentive polymer can be any hydrophilic polymer that can absorb at least 50 times its own weight in aqueous fluid and retain the fluid under pressure.

Preferably, the water-retentive polymer is a polymer that can absorb between 50 and 600 times its weight, more preferably between 300 and 600 times its weight. At such absorption levels, the polymer will provide the required water to the seed or plant for a relatively long period of time. The amount of water that can be absorbed by a polymer in proportion to the weight of the polymer can be easily determined by saturating preweighed dry polymer without added water, then reweighing the polymer after it has become saturated with water and calculating the difference.

Water-retentive polymers or "SAP's" are generally synthesized by one of two methods. In the first method, a water soluble polymer is cross-linked so that it can swell between cross-links but not dissolve. The

polymer, "STOCKOSORB 300Z", behaves in this manner. In the second method, a water-soluble monomer is copolymerized with a water-insoluble monomer into blocks.

Preferably, the water-retentive polymer is selected from the group consisting of cross-linked potassium acrylate-acrylamide copolymers, cross-linked

poly (acrylamide), cross-linked poly (vinyl pyridine) (acrylic acid) copolymers and ionomers, cross-linked poly (vinyl pyridine) (ethylene oxide), saponified acrylonitrile grafted starch, cellulose and cellulose derivatives, acrylic acid grafted starch, poly (vinyl pyridine) (maleic acid) copolymers, cross-linked poly (vinyl pyridine) (vinyl alcohol) copolymers, vinyl alcohol and methyl acrylate copolymers, vinyl alcohol and acrylamide copolymers, poly (vinyl pyridine)-(vinyl pyrrolidone), sulfonated polystyrene, polyphosphates, polyethylene amine, poly (vinyl pyridine) (vinyl

pyridine) and sodium propionate-acrylamide. The most preferred water-retentive polymer for use in connection with the inventive composition is a acrylamide potassium acrylate copolymer. As shown by Examples 3-32, a crosslinked acrylamide potassium acrylate copolymer marketed under the trade name "STOCKOSORB 300Z" by the

Stockhausen Chemical Co. is very effective.

The exact amount of the water-retentive polymer that should be employed in the inventive composition depends on the amount of water that is sought to be absorbed. The greater this amount, the higher the proportion of water-retentive polymer should be. Environmental factors such as exposure to rainfall and ambient

humidity are also important considerations. Preferably the water-retentive polymer is present in the

composition in an amount in the range of from about 1% to about 25%, more preferably from about 5% to about 15%, and most preferably from about 10% to about 13%, by dry weight based on the total dry weight of the

composition.

Optional Components

If desired to enhance the structural integrity of the composition, in the range from about 0% to about 12% by dry weight, based on the total dry weight of the composition, a separate water-soluble binding agent can be included in the inventive composition to help keep the composition intact prior to the addition of water thereto or, for certain application, to keep the

composition intact even after water is added thereto. The binding agent can be as long as it is a different material or mixture of materials than the bulking agent and water-retentive polymer.

When the composition is to be used in applications which require the composition to retain its structural integrity even after water is applied thereto, the binding agent is preferably insoluble in cold water. For example, in applications in which a seed is

germinated and/or a seedling is grown in the composition and the seedling is to be transplanted with roots embedded in the composition, a binding agent that is insoluble in cold water is required to prevent the composition from falling apart when water is applied thereto. In applications where maintenance of the structural integrity of the composition after water application is not important, such as when the

composition is used as a substitute for conventional potting soil in potting applications, the binding agent can be soluble in cold water. Regardless of the end use of the composition, a binding agent that is soluble in hot water is preferred. This allows the binding agent to impregnate the bulking agent during processing of the composition.

The binding agent is preferably poly (vinyl alcohol), the poly (vinyl alcohol) being at least partially

hydrolyzed. Because it is soluble in hot water but insoluble in cold water, substantially fully hydrolyzed poly (vinyl alcohol) is preferred when the composition is to be used in applications which require the composition to retain its structural integrity even after

applications of water thereto. As used herein and in the appended claims, poly (vinyl alcohol) that is at least partially (80%) hydrolyzed is preferred.

Generally, the molecular weight of the poly(vinyl alcohol) should be from 10,000 to 150,000. Preferably, the molecular weight of the poly (vinyl alcohol) is from about 10,000 to 50,000.

Poly (vinyl alcohol) that is partially hydrolyzed and has a suitable molecular weight can be obtained from E. I. du Pont de Nemours and Company (Elvanol®).

The amount of binding agent that should be employed depends on the degree of structural integrity desired in the composition for shipping, handling and

transplanting. The binding agent is preferably employed in an amount from about 1% to about 12%, by dry weight, based on the total dry weight of the matrix composition. Applicants used approximately 12% PVA (Elvanol® 7130,

E. I. du Pont de Nemours and Company). The particular PVA has a molecular weight of approximately 50,000.

Other water soluble binders can be used in the invention including polyvinylpyrrolidone.

Although use of composted rice hulls as part of the bulking agent makes it unnecessary for most application, in the range of from about .001% to about 0.35% by dry weight, based on the total dry weight of the

composition, a separate nonionic surfactant can also be included in the composition for various reasons such as to decrease surface tension and further increase the rate at which the bulking agent absorbs water. The nonionic surfactant wets the bulking agent resulting in a better blend of the bulking agent with the binding agent. Any nonionic surfactant that acts to decrease surface tension will increase the rate of wetting and is suitable for this invention, and is a different material or mixture of materials than the bulking agent and water-retentive polymer can be employed. Preferably, the nonionic surfactant is selected from the group consisting of polyoxypropylene-polyoxyethylene block copolymers; alkanol amides; betamol derivatives; block copolymers comprising a series of condensates of

ethylene oxide with hydrophobic bases formed by

condensing propylene oxide with propylene glycol;

ethoxylated compounds comprising alcohols, alkyl

phenols, amines and amides; alkylphenol ethoxylates;

fatty alcohol polyglycol ethers; and oxo-alcohol

polyethyleneglycol ethers. The nonionic surfactant is preferably selected from polyoxypropylene-polyoxyethylene block copolymers. The polyxoypropylene-polyoxyethylene block copolymer is preferred because it provides a very high rate of wetting. An example of a polyoxypropylene-polyoxyethylene block copolymer very suitable for use in the inventive composition (Pluronic®) can be obtained from BASF.

It is also desirable to include a small amount of water in the composition before the matrix is processed into its final form to activate the polymer to an extent sufficient to bind the composition together and/or activate the binding agent. As used herein and in the appended claims, "to activate" means to cause the reference component or group of components to perform the function described. The amount of water that should be used in the potting soil substitute depends on the overall moisture content of the other components and the anticipated end use of the product. The amount of water is in the range of about 0% to about 15% by weight based on the total dry weight of components of the wafer.

Various other additives such as pesticides, dyes, nutrients and plant growth regulators can advantageously be employed in the composition depending on the intended use of the composition. Fertilizers are retained with water absorbed by the polymer and released with the water as needed by the plant.

The particular components and exact amounts thereof that should be used to form the inventive composition will vary depending on certain factors such as the anticipated end use and various conditions associated therewith. When the matrix composition is to be formed into articles such as chip-like wafers for end use as a potting soil substitute, it most preferably comprises about 60-85% by dry weight commercial peat, about 2-30% by dry weight composted rice hulls (e.g., Butler Rice Hull Compost Co., N. Little Rock, AR), about 5-12% by dry weight acrylamide potassium acrylate copolymer (e.g., STOCKOSORB 300Z, Stockhausen, Inc.). If a nonionic surfactant is used in the matrix composition, it is most preferably used in an amount of about .25% by dry weight based on the total dry weight of the

composition.

The matrix composition can be compressed and formed into articles of any size and shape depending on the intended end use of the product. For example, articles can be custom made for specific pot or bed dimensions. When it is to be used as a substitute for conventional potting media, the composition is preferably compressed into chip-like wafers. This allows the matrix to be easily handled, shipped and stored. Appropriate

packaging to maintain a particular desired moisture content of the composition after it is produced can be employed if needed.

The composition can be compressed into articles by feeding the blended composition to an automated press (e.g.. Stokes Model R-4 Powder Metal Press) and applying pressure thereto. Generally, a composition (in equal volumes) of about 60% by dry weight peat and 28% by dry weight rice hulls need a total force of at least 24 tons applied to achieve sufficient compaction.

The inventive composition can be used for a variety of purposes. The composition is believed to be

particularly useful as a substitute for conventional potting media. The composition is also useful as a material for encapsulating or covering seeds and/or protecting seedlings during transplantation.

For example, the inventive composition can be used as a potting medium in which to plant house plants. One or more chip-like wafers formed of the composition are placed in a pot (e.g., one 2.5" by 0.5" wafer 4-inch pot) and water is added thereto. The wafer(s) quickly absorb the water and expand to fill the pot. After complete wafer absorption, the matrix composition is easily worked with. One or more plants can be planted in the composition in the same way plants are potted in conventional potting soil. The composition is porous and permits exchange of gases between the plant (s) and the environment. Because the composition retains water and releases it to the plant (s) as required thereby over a relatively long period of time, the plants require less frequent watering than when conventional potting soil is used. The retention and slow release of water is believed to help prevent over- or under-watering of the plant (s). Various additives such as fertilizers, pesticides, and growth hormones and the like can be advantageously included in the composition if desired.

Seedlings started in articles formed of the

inventive composition can be easily transplanted. For example, seeds can be germinated and seedlings grown in the composition. Once the seedlings are sufficiently mature, the seedlings can be placed in conventional potting soil or otherwise transplanted to permanent locations.

In order to illustrate and facilitate a clear understanding of this invention, the following Examples are given.

EXAMPLE 1

Preparation of Potting Medium Wafer Composted rice hulls and commercial peat moss were placed separately in an 85°C oven and dried to a

moisture content of between 10% and 15%, as ascertained using an Ohause Moisture Analyzer, Model 6010PC. The moisture content was not recorded since subsequent handling and storage before wafer formation resulted in minor changes in water content. One hundred mls. of loose packed composted rice hulls and 100 mls. of tight packed peat moss were dry blended in a bag, with 4.65 g of the water retentive polymer, acrylamide potassium acrylate copolymer (STOCKOSORB 300K, Stockhausen, Inc.). The resulting blend thus had the resulting dry weight percentages of each component by calculation: 15% water retentive polymer, acrylamide potassium acrylate

copolymer (STOCKOSORB 300K, Stockhausen, Inc.); 51.6% composted rice hulls; and 33.4% commercial peat moss. The dry blend material was then pressed into a 2.5" diameter wafer using a Carver Laboratory Press at 20 metric tons.

EXAMPLE 2

Volume Fill Alteration and Bulk Density Calculation

Using the basic procedure as in Example 1, the volume of commercial peat moss was altered from a tight packed to non-packed or loose filled volume. Relative bulk densities were determined as follows:

*As determined by Ohause Moisture Analyzer, Model

6010PC, at <1% moisture.

Relative bulk densities (Dry weight. Composted Rice Hulls: Peat Moss):

90 ml: 90 ml Blend = 2.224:1

100 ml: 100 ml Blend = 2.108:1

Bulk Density = 2.166:1

EXAMPLES 3A TO 37A

Wafer Composition and Hydration Evaluation

The samples described in Example I were tested to determine the rate at which they absorbed water and the final volume of end product they produced upon

absorption of a set amount of water. Using the same procedures and calculations in Example 2, compositions were made varying the amounts of ingredients to give the following volume to volume ratios and calculated percent compositions (on a dry weight basis).

STOCKOSORB

Volume (ML) % Composition 300K

Example

No. Peat C.R. Hulls Peat C .R . Hulls GM Percent

3 10 10 14.8 32.0 3 53.2

4 20 20 20.1 43.6 3 36.3

5 30 30 22.9 49.6 3 27.5

6 40 40 24.6 53.3 3 22.1

7 50 50 25.7 55.7 3 18.6 STOCKOSORB

Volume (ML) % Composition 300K

Example

No. Peat C.R. Hulls Peat C.R. Hulls GM Percent

8 60 60 26.6 57.5 3 15.9

9 70 70 27.2 58.8 3 14.0

10 80 80 27.7 59.9 3 12.4

11 90 90 28.1 60.7 3 11.2

12 90 90 28.1 60.7 3 11.2

13 100 100 28.4 61.4 3 10.2

14 90 90 29.1 63.1 2 7.7

15 90 90 28.6 61.9 2.5 9.5

16 90 90 27.0 58.5 4 14.5

17 90 90 27.0 58.5 4 14.5

18 90 90 26.1 56.5 5 17.4

19 90 90 26.1 56.5 5 17.4

20 20 0 39.7 0 3 60.3

21 40 0 56.8 0 3 43.2

22 60 0 66.4 0 3 33.6

23 80 0 71.8 0 3 28.2

24 100 0 76.7 0 3 23.3

25 120 0 79.8 0 3 20.2

26 140 0 82.2 0 3 17.8

27 160 0 84.0 0 3 16.0

28 180 0 85.6 0 3 14.4

29 180 0 85.6 0 3 14.4

30 200 0 86.8 0 3 13.2

31 180 0 89.9 0 2 10.1

32 180 0 87.7 0 2.5 12.3

33 180 0 81.6 0 4 18.4

34 180 0 81.1 0 4 18.9

35 180 0 77.5 0 5 22.5

36 180 0 77.5 0 5 22.5

37 180 0 54.2 0 15 45.8 Examples 3a-19a when compared to Examples 20a-37a demonstrate the superior hydration performance of potting media containing composted rice hulls over a composition without composted rice hulls.

EXAMPLES 3B TO 37B

Wafer Composition and Hydration Evaluation (Continued)

Water was added to the varying wafer compositions shown in Examples 3a-37a. Final pot volumes and the duration from water addition to no free water was recorded and are shown in Examples 3b-37b. To carry out tests. Pre-measured amounts of water were added to a 600 mL beaker. Each wafer was placed in the 600 mL graduated beaker which was already filled with the indicated amount of water. The "time to no free water" was measured from the initial addition of the wafer until no free water was observed standing in the pot. "Final pot volume" was measured upon complete water absorption.

Water Finale Pot Time to No

Example No. Added (ML) Volume (ML) Free Water (Min)

3 325 350 7.5

4 325 375 4.75

5 325 375 4.0

6 325 425 4.75

7 325 450 4.25

8 325 475 3.5

9 325 500 3.5

10 325 475 4.0

11 325 550 3.0

12 500 575 2.75

13 325 550 2.75 Water Finale Pot Time to No

Example No. Added (ML) Volume (ML) Free Wafer (Min)

14 325 400 4.0

15 325 400 4.0

16 325 550 2.25

17 500 625 2.25

18 325 575 2.0

19 500 650 2.0

20 325 330 8.0

21 325 330 9.5

22 325 340 6.0

23 325 340 6.0

24 325 350 5.5

25 325 350 5.25

26 325 360 4.25

27 325 365 4.15

28 325 365 4.15

29 500 550 45 + (Free water present)

30 325 370 6.75

31 325 375 11.0

32 325 380 11.25

33 325 385 6.0

34 500 500 7.75

35 325 390 3.65

36 500 550 5.25

37 500 700 4.5

Examples 3b-19b when compared to Examples 20b-37b demonstrate the superior hydration performance of potting media containing composted rice hulls over a composition without composted rice hulls. EXAMPLES 38 TO 40

Wafer Composition and Hydration Evaluation Peat moss, 75.8 gms (on a dry weight basis), was placed in a plastic bag. Forty-five milliliters of a distilled water solution containing 0.19 gm of

surfactant, poloxypropylene-polyoxethylene block

copolymer (Pluronic® L92, BASF), were added to the above peat moss, hand blended in the plastic bag, and dried in an oven at 85°C as in Example 1 to 10.5% moisture content, as ascertained using an Ohaus Moisture

Analyzer, Model 6010PC. The resulting blend thus had the following dry weight percentages of each component of the total non-aqueous ingredients by calculation: 0.25% surfactant (Pluronic® L92, BASF) and 99.75% peat moss. Using the basic procedures in Example 2, the following relative densities were determined.

Using the same procedures as in Example 2,

compositions were made varying the amounts of

ingredients to give the following volume to volume ratios and calculated percent compositions (on a dry

weight basis).

Volume (ml) % Composition STOCKOSORB 30 O C.R. C.R. Pluronic®

Example No . Peat Hulls Peat Hulls L92 GM percent

38 40 0 49.88 0 0.12 3 50

39 100 0 71.3 0 0.2 3 28.5

40 180 0 81.6 0 0.2 3 18.2

Final pot volumes and the duration from water

addition to no free water was determined as in Examples

3b-37b and recorded.

Time to

Water Final Pot No Free

Example No . Added (ml) Volume (ml) Water (min)

38 325 330 6.0

39 325 350 5.0

40 325 360 4 .15 The U.S. patent application, U.S.S.N. 07/567,816,

states that the preferred hydrophilic fibrous bulking

agent to be commercial peat moss and that the preferred water-retentive polymer to be acrylamide potassium

acrylate copolymer (Viterra, Nepara Chemical Co.). As

compared to the results of Example 13 in the preceding

tables, a wafer composed of 200 ml commercial peat moss

plus 3 gm of water-retentive polymer, acrylate

acrylamide copolymer (Viterra, Nepara Chemical Co.)

hydrated with 325 ml water required 7.5 minutes to no

free water with a final pot volume of 450 ml. EXAMPLES 41-45 AND EXAMPLE 46

Wafer Composition. Greenhouse Plant

Growth. Water Relationships and Control

Using the same procedures and calculations in

Example 2, compositions were made varying the

hydrophilic bulking agent ratios to give the following percentage combinations (on a dry weight basis using 200 total milliliters of bulking agents). All wafers, regardless of the hydrophilic bulking agent ratios, received 3 grams of water-retentive polymer, acrylamide potassium acrylate copolymer (STOCKOSORB 300K,

Stockhausen, Inc.).

Volume (ml) % Composition STOCKOSORB 300K

C.R. C.R.

Example No. Peat Hulls Peat Hulls GM Percent

41 200 0 84.7 0 3 15.3

42 150 50 51 36.8 3 12.2

43 100 100 28.4 61.4 3 10.2

44 50 150 12.2 79.0 3 8.8

45 0 200 0 92.3 3 7.7 EXAMPLE 46 (CONTROL)

100% Commercial Quality

Premixed Potting Soil

Table 1 gives the results of the greenhouse plant growth responses to wafer Examples 41-46. Ornamental Coffee Plants were transplanted, bare rooted, into

4-inch round pots containing each wafer Examples 41 to 46. Wafers were initially hydrated and watered with a 26 ppm solution of Peters "Peat-Lite Special", 20-10-20, fertilizer (Peters Fertilizer Products, W. R. Grace & Co., Cambridge, MA). Experimental design is a

randomized complete block with five replications. Changes in plant height were recorded 26 days after an initial height measurement.

The results of Table 1 show that use of composted rice hulls as part of the bulking agent, specifically in amounts ranging from approximately 36-61% by dry weight based on the total dry weight of the composition, causes the inventive composition to achieve significantly better growth of plants than do compositions using pure peat as the bulking agent.

The water relationship results, for Examples 41-46, appear in Table 2. A completely randomized design with three replications was used. Each sample was placed in a 4-inch pot having drainage openings in its bottom surface. Each pot, including the inventive composition contained thereby (hereinafter referred to collectively as a "pot"), was then weighed and placed on a bench under ambient conditions. Total water evaporation was recorded (in grams) after 18 days. Three hundred milliliters of water was then poured through each 4-inch pot. The free water passing through the pot was

contained and measured. The amount of water retained in the matrix was calculated as the percentage of the original, fully hydrated, pot weight. Each pot was allowed to stand in a saucer with 200 ml of water for 10 minutes, after which the amount of water absorbed

through capillary action was calculated based on the amount of free water still remaining in each saucer. A percent of the original hydrated weight was calculated. No plant species were present in pots. TABLE 2

Rehydration from

Initial RehyCapillary Action

Water Loss dration as % of as % of Original per Pot After Original Pot Pot Weight

Example No.¹ 18 Days (gm) ² Weight³ After 10 minutes⁴

41 202 76 99

42 178 72 96

43 169 83 107

44 154 81 107

45 178 76 95 ¹ Three replications per sample.

² Average percent by weight, based on the original pot weight (at beginning of 18 day period), of water held by the composition in each pot after 300 mLs water poured into each pot.

3 Average percent by weight, (assuming 1 mL of water = 1 g of water) based on the original pot weight (at

beginning of 18 day period), of water held by the composition in each pot after allowing each pot to stand in a saucer containing 200 mLs of water for ten minutes.

The above test shows that use of composted rice hulls as part of the bulking agent reduce water loss as compared to peat alone.

The preceding examples can be repeated with similar success by substituting the generically or specifically described components and/or operating conditions of this invention for those used in the examples.

From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and

modifications of the invention to adapt it to various usages and conditions.

EXAMPLE 47

Surface Area Evaporation

Table 3 and Table 4 give the results of a laboratory trial, under ambient conditions, comparing the surface evaporation of EZ Soil¹ and Metro-Mix 250 (Grace

Horticultural Products, W. R. Grace & Co., Cambridge, MA). The experiment was a completely randomized design with 20 replications per treatment (two treatments: EZ Soil and Metro-Mix 250). Similar amounts of Metro-Mix (97 to 102 gm) were added to 4-inch commercial pots.

Pots were sub-irrigated until free water was visible at the top of the media (30 to 50 minutes). One EZ Soil wafer (2.5" diameter by 0.5" thick, average weight 26.3 gm on a dry weight basis) was added to 4-inch commerical pots. Pots were sub-irrigated until free water was visible at the top of the media (30 to 70 minutes). All pots were set on a rack that allowed all free water to drain from the bottom (approximately 30 minutes).

Initial weights and subsequent weights were taken over a period of 31 days.

TABLE 4

Media Percent Water Loss¹

Type 3 days 7 days 10 days 15 days 17 days

Ez-Soil² 17 44 61 72 77

MetroMix 250 17 55 69 81 84

Standard

Deviation 3 7 8 6

20 days 24 days 27 days 31 days

Ez-Soil² 79 84 88 91

Metro- 87 92 95 96

Mix 250

Standard 6 5 5 4

Deviation

1 All values are calculated on a dry weight basis.

2 Wafer composition on a dry weight basis:

Commercial peat moss - 72%

Composted rice hulls - 16%

Acrylamide potassium acrylate - 12%

copolymer (STOCKOSORB 300K,

Stockhausen, Inc.) water-retentive

polymer

EXAMPLE 48

Efficacy Comparisons

Various greenhouse trials were conducted comparing the efficiency of EZ Soil to Metro-Mix 250 (Grace

Horticultural Products, W. R. Grace Co.). Experimental design was a randomized complete block with 3 to 4 replications. Acrylamide potassium acrylate copolymer (STOCKOSORB 300K, Stockhausen, INc.) was used as the water-retentive polymer in EZ Soil. EZ Soil

compositions (on a dry weight basis) are as follows:

% Composition STOCKOSORB 300K

Example No. Peat C. R. Hull GM Percent

48 28 59 3 13

EXAMPLE 49

Commercial Wafer for In Home, General

Ornamental Horticultural Use, at Present The EZ Soil wafer is composed of 180 mLs of

hydrophilic fibrous bulking materials and 3.2 g per wafer of water retentive polymer, acrylamide potassium acrylate copolymer (Stockosorb 300Z, Stockhausen, Inc.). Based on twenty replications, the average wafer weight is 29.9 gms. Taking four wafers and determining the percent moisture (using an Ohause Moisture Analyzer, Model 6010Pe, at <1% moisture), the average percent moisture of the wafer was calculated to be 10.93%. The percent compositions (on a dry weight basis) are given for Example 49 (assuming zero percent moisture in the water retentive polymer, acrylamide etc.) using the X bulk density ratio in Example 2.

Volume (mi) % Composition STOCKOSORB 300Z

C. R. C. R.

Example No. peat. Hulls Peat Hulls GM Percent

49 135 45 76.3 11.85 3.2 11.85 EXAMPLES 50 TO 52

Percent compositions (on a dry weight basis) were calculated using the procedures in Example 49. It is assumed that the final wafer weight (average) is targeted to 29.9 g and the wafer percent moisture

(average) is targeted to 10.93% as in Example 49. All other assumptions, procedures and materials are presumed in Examples 50 to 52. Volume (ml) % Composition STOCKOSORB 300Z

C.R. C.R.

Example No. Peat Hulls Peat Hulls GM Percent

50 45 135 37.04 51.11 3.2 11.85

51 90 90 60.37 27.78 3.2 11.85

52 171 9 85.93 2.22 3.2 11.85

Table 5 contains the results of the greenhouse trials on various plant species. Relative growth and watering frequencies are recorded.

TAB LE 5

TREATMENTS³ AVERAGE

# of WATERING

26 PPM 52 PPM 78 PPM 104 PPM 208 PPM per POT⁴

PLANT¹ RELATIVE²

SPECIES GROWTH EZ MM EZ MM EZ MM EZ MM EZ MM EZ MM

Chinese (mm of

Evergreen Growth)

30 days 0.375 0 .75 .75 - - - - - - 1.125 .875 4 . 0 .25 2.0 5.1

(30 days)

Glacier Ivy (mm of

Growth) 3.0 4.125 22 days 3.375 2.575 4.625 2.125 5.95 3.475 2.425 3.125 - - - - - - (32 days)

+10 days 1.575 2.15 1. 975 2.35 3.425 1.2 2.8 2.55 - - - - - -

TOTAL GROWTH 4.95 4.725 6. 6 4.475 9.375 4.675 5.225 5.675 - - - - - -

TREATMENTS³ AVERAGE

# of WATERING

26 PPM 52 PPM 78 PPM 104 PPM 20B PPM per POT⁴

PLANT¹ RELATIVE²

SPECIES GROWTH EZ MM EZ MM EZ MM EZ MM EZ MM EZ MM

Nephthytis (# of

leaves)

16 days 2.33 0 1.83 1.66 - - - - - - - - - - - - - - - - - - 1.7 3.3

(41 days)

+36 days 3.33 2.66 4.33 2.66 - - - - - - - - - - - - - - - - - -

+34 days 1.0 2.0 3.33 0 - - - - - - - - - - - - - - - - - -

TOTAL GROWTH 6.66 4.66 9.49 4.32 - - - - - - - - - - - - - - - - - -

Red (mm of

Fittonia Growth)

32 days 5.76 6.75 6.0 10.5 10.5 8.0 10.75 10.25 - - - - - - 2.6 4.9

(32 days)

TREATMENTS³ AVERAGE

# of WATERING

26 PPM 52 PPM 7fl PPM 104 PPM 208 PPM per POT⁴

PLANT¹ RELATIVE²

SPECIES GROWTH EZ MM EZ MM EZ MM EZ MM EZ MM EZ MM

Maranta (# of

Leaves)

16 days 2.66 1.0 1.33 2.0 - - - - - - - - - - - - - - - - - - 2.0 2.8

(45 days)

+36 days 3.66 3.5 5.66 4.66 - - - - - - - - - - - - - - - - - -

+34 days 3.33 2.5 4.0 5.66 - - - - - - - - - - - - - - - - - -

TOTAL INCREASE 9.65 10.99 7.0 12.32 - - - - - - - - - - - - - - - - - -

White (# Of

Fittonia leaves)

26 days 7.0 8.0 8.5 7.8 - - - - - - 7.5 5.0 8.0 6.0 2.1 3.1

(26 days)

¹ Chinese evergreen, Aglaonema costatum, var. "Silver Queen"; Glacier Ivy, Hedera helix, var. "Glacier"; Nephthytis, Syngonium podophyllum, var. "Imperial white"; Red fittonia, Fittonia verachaffeltii var. pearcei, mosaic plant; Maranta leuconeura erthroneura, Red veined prayer plant; and White fittonia, Fittonia verschaffeitii var. argyroneura, "Nerve Plant".

² mm = Millimeters; # = Number

³ EZ = EZ Soil; MM = Metro-Mix 250; ppm denotes the parts per million concentration of the soluble

fertilizer (Peters "Peat-Lite Special" 20-10-20 fertilizer, Peters Fertilizer Products, K. R. Grace and Co.) used at each watering.

⁴ EZ = EZ Soil; MM = Metro-Mix 250; Pots watered on an as needed basis.

EXAMPLE 53

Applicants compressed the following matrix

composition into 2" × 3/8" chip-like wafers with 7500 psi:

12% by dry weight PVA (Elvanol™ 7130,

E. I. du Pont de Nemours and Company) 15% by dry weight water retentive polymer

(Viterra™, Nepera Chemical Company),

7.5% 360E grade/7.5% 375 grade

0.35% non-ionic surfactant (Pluronic™

L-92, BASF)

72.65% hydrophilic bulking agent (peat)

Sufficient water is added to trigger the water retentive polymer enough to bind the wafer together during production.

The matrix wafers were then moistened to fully activate the water retentive polymer and the resulting matrix used as potting soil in which to plant house plants. The size of the wafer was determined by reference to the standard size flower pot the matrix would expand to fill. Preliminary growing trials were run with squash, watermelon, cantaloupe, bell pepper and okra plants over a two month period. No deleterious effects were noted from use of the matrix and water retention of the matrix was considered a convenience and advantage.

A variety of house plants were potted in the matrix including Pathos, Aglaonema, "China Doll", Rex Begonia, Calathea, Draconia, Diffenbachia, Boston fern. Aloe, Croton, and "Peace Lily". No deleterious effects from use of the matrix were noted. Comparable specimens of Pathos, Aglaonema, "China Doll", and Rex Begonia were planted in the matrix and in conventional potting soil. Each was watered once to saturation at the outset of the trial period and like species were compared after 20 days (Pathos, Aglaonema) and 10 days ("China Doll", Rex Begonia). All of the house plants planted in

Applicants' matrix showed a more healthy appearance than those planted in conventional potting soil. Evidence of advantageous effects included glossier leaves, no wilting, more growth, and no browning of leaves.

Applicants believe that the matrix's ability to release water on an as-needed basis accounts for the superior results of these trials.

Applicants have also used the following matrix as a potting soil substitute without any deleterious effects to potted plants noted:

15% by dry weight water retentive polymer

(Viterra™, Nepera Chemical Company),

7.5% 360E grade/7.5% 375 grade

0.35% non-ionic surfactant (Pluronic™

L-92, BASF)

84.65% hydrophilic bulking agent (peat)

It will be apparent that the instant specification and the examples are set forth by way of illustration and not limitation, and that various modifications and changes may be made without departing from the spirit and scope of the present invention.

Claims

What is claimed is: 1. A water-retentive composition for growing plants comprising:

(a) a bulking agent in the range of from about 50% to about 99% by dry weight, based on the total dry weight of the composition, said bulking agent comprising composted rice hulls in an amount ranging from at least 2% by dry weight, based on the total dry weight of the composition;

and

(b) a water-retentive polymer having a water absorbency of between 50 and 600 times its weight, said water retentive polymer being present in an amount ranging from about 1% to about 25%, based on the total dry weight of the composition.

2. The composition of Claim 1 wherein said water-retentive polymer is a cross-linked acrylamide potassium acrylate copolymer.

3. The composition of Claim 1 further comprising:

.(c) a water-soluble binding agent, in the range of from about 1% to about 25% by dry weight, based on the total dry weight of said composition, said components (a)-(c) being different materials or mixtures of materials.

4. The composition of Claim 3 wherein said binding agent is poly(vinyl alcohol), said poly(vinyl alcohol) being at least partially hydrolyzed.

5. The composition of Claim 1 further

compromising:

(d) in the range of from about .001% to about .35% by dry weight, based on the total dry weight of the composition, of a nonionic surfactant, said components (a)-(d) being different materials or mixtures of

materials.

6. The composition of Claim 5 wherein said

surfactant is a polyoxypropylene-polyoxyethylene block copolymer.

7. The composition of Claim 1 further comprising:

(c) water in an amount up to about 15% by

weight based on the total dry weight of components (a) and (b).

8. The composition of Claim 1 further comprising at least one additive selected from the group consisting of pesticides, dyes, fertilizers,and plant growth regulators.

9. A water-retentive matrix composition for growing plants comprising:

(a) a bulking agent in the range of from about

80% to about 90% by dry weight, based on the total dry weight of the composition, said bulking agent comprising composted rice hulls in an amount ranging from about 10% to 30% by dry weight and peat in an amount ranging from about 60% to about 80% by dry weight, said weight percentage based on the total dry weight of the composition;

and

(b) a cross-linked acrylamide potassium acrylate copolymer in the range from about 3% to about 12% by dry weight, based on the total dry weight of the composition, said copolymer having water absorbency of between 50 and 600 times its weight.

10. An article formed by compressing the

compositions of Claims 1 or 9 to obtain said article in the form of a substantially round disk.