AU624413B2 - Method of preparing granular culture soil - Google Patents

Description

Wl J JIMlI 1 y.n 1n File: D.B. K-24 Fee: $297.00 d: a.0. C 1 9 e9 j d Ix~ a: ,1 i, L L COMMONWEALTH OF AUSTR) kLZA"B PATENTS ACT 1952 C A M P F Rr

SPECIFICATION

C 0 M P L E T E S P E C I F I C A T 1 0 N FOR OFFICE USE: Class Int.Class Application Number: Lodged: Complete Specification Lodged: Accepted: "Published: lt Priority: "*Related Art: 4 0

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Name of Applicant: Address of Applicant: U o p 9% *Jctual Inventor: KYORITSU YUKI CO., LTD. and RIHACHI SHIRAI 7-13-15, Ginza, Chuo-ku, Tokyo, Japan and 272 Aza-Kitajima, Kitajimacho, Toyohashi-shi, Aichi-ken, Japan, respectively.

Rihachi Shirai and Kiyoshi Aoyama Address for Service: SHELSTON WATERS, 55 Clarence Street, Sydney 0 Complete Specification for the Invention entitled: "METHOD OF PREPARING GRANULAR CULTURE SOIL" The following statement is a full description of this invention, including the best method of performing it known to us:- 1 i~

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f 00I 0 0 0 0000 00 0 0 0 0000 0 10 a oo =n yiri ABSTRACT OF THE DISCLOSURE The present invention relates to a method of preparing a granular culture soil having excellent water retention and air permeability and suitable for the growth of plant. Such a granular culture soil is prepared by granulating a hydrous soil containing a highly water-absorptive resin and a water-soluble organic polymer and drying the formed granules. The highly water-absorptive resin and the water-soluble organic polymer may be simultaneously or successively added to the soil. The content of each of the resins is 0.1 to 10% by weight based on the whole dry solid, and the hydrous soil containing both the resins is granulated into a sphere or a pellet having a diameter of 1 to 10mm. The highly water-absorptive resin used in the present invention has a water absorption ratio of 100 as determined in purified water, and the water-soluble organic polymer has a limiting viscosity number of 0.2 to dt/g.

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SPECIFICATION

TITLE OF THE INVENTION METHOD OF PREPARING GRANULAR CULTURE SOIL BACKGROUND OF THE INVENTION Field of the Invention o, The present invention relates to a method of preparing a granular culture soil having excellent water retention and air permeability and suitable for the growth of plant.

O a o Description of the Prior Art It is widely known in the agricultural field that the soil having an aggregate structure is a o a o a a suitable for the growth of plant. Further, it is believed that the supply of humus is effective in a 4 15 forming aggregates from soil granules. However, the humus is susceptible to biodegradation and therefore should be supplied every year. For this reason, as an alternative to the humus, a proposal has been made on the use of a soil aggregating agent 20 comprising a water-soluble organic polymer such as polyacrylamide, polysodium acrylate, and polyvinyl alcohol. Examples of the soil aggregating agent comprising a water-soluble organic polymer include an easily soluble powdery soil aggregating agent lbi I i i 1 :j j; I;r; r i i* i 'o" it iB~ i;

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1-: ~1 ;_i 1;1 Ilr I -i i91 -2 1< disclosed in Japanese Patent Laid-Open No.73790/1986.

This agent comprises an acrylic water-soluble organic polymer powder and, incorporated therein, a dihydrogenphosphate powder and a hydrogencarbonate powder.

Further, a proposal has been made on the incorporation in soil of a highly water-absorptive resin having water retention for the purpose of promoting the growth of plant on an arid land.

Examples of a method of preparing a soil containing a highly water-absorptive resin incorporated therein include a method of preparing a polymer material having excellent water absorptivity as disclosed in o Japanese Patent Laid-Open No. 94011/1982 and a fertilizer for agricultural and horticultural use and a method of preparing the same as disclosed in 0 0 Japanese Patent Laid-Open No. 44784/1986.

However, it is difficult to prepare a solid granular culture soil through mere incorporation of a highly water-absorptive resin. A culture soil prepared by mixing clay with a water-soluble resin, granulating the mixture, and drying the formed granules is poor in the water retention, because the product has a structure like that of a dense brick. On the other hand, when a highly waterabsorptive resin is directly applied to soil and 2

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mixed therewith, only the highly water-absorptive resin powders concentrate on the surface layer or form a coating in the soil due to a difference in the specific gravity between the water-absorptive resin and the soil, which exerts an adverse effect on the water permeability and air permeability of the soil.

oo o SUMMARY OF THE INVENTION 0 0 o. An object of the present invention is to solve 0C00 0 "000 the above-described problem by preparing a solid 0 o .a o o..t granular culture soil suitable for the growth of 0000 plant.

Another object of the present invention is to oa'oo provide an adequate method for applying a highly o oo15 water absorptive resin to soil, and thereby to avoid 0 0 0 that the highly water-absorptive resin powders 0000 concentrate on the surface layer or form a coating in the soil.

A further object of the present invention is to provide an adequate method for mixing a water-soluble organic polymer with the clay, and thereby to assure the water retention and air permeability by avoiding the formation of the dense structure.

A further object of the present invention is to 3

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provide a method of preparing a granular culture soil suitable for the growth of plant by granulating clay particles.

A further and the most concrete object of the present invention is to provide the most suitable operation procedures, operation conditions and quality of raw materials for producing a granular culture soil keeping excellent water retention, air permeability and physical strength for a long time.

0 0ao In the present invention a method of preparing a granular culture soil comprises a step of adding a highly water-absorptive resin and a water-soluble °B organic polymer to fine soil particles and kneading the mixture, a step of granulating the resultant 6 0 9 hydrous soil containing a highly water-absorptive resin and a watersoluble organic polymer, and drying the formed granular hydrous soil. If required this i granular hydrous soil may be mixed with other normal soil.

The highly water-absorptive resin and the water-soluble organic polymer may be simultaneously or sccessively added to the soil. The content of -4- 4 i i each of the resins is 0.1 to 10% by weight based on the whole dry solid, and the hydrous soil containing both the resins is granulated. Preferably, the hydrous soil containing both the resins is granulated into a sphere or a pellet having a diameter of 1 to 10mm. The highly water-absorptive resin used in the present invention has a water absorption ratio of 100 as determined in purified water, and the water-soluble organic polymer has a limiting viscosity number of 0.2 to 20 dl/g.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The above-described steps are conducted under the following conditions.

In the method of preparing a granular culture soil o 9o according to the present invention, the fine soil particle is preferably a component having a particle diameter of 0.01" mm or less and defined as "clay" by the Japanese Association of Agricultural Science Societies, because it is favorable for the growth of plant by virtue o f of its high base substitution capacity. This kind of clay can be inexpensibly available from sludge generated in a water purifying plant, a gravel washing place, a porcelain clay plant, etc. It is also collected from a clay layer in the soil. With respect to the highly i water-absorptive resin added and mixed in the clay, it is 5 Tl'^ possible to use one which exhibits a water absorption ratio of 100 as determined in purified water, and examples thereof include crosslinked polymers having the following composition. Examples of the highly water-absorptive resin used in the present invention include poly(meth)acryloyloxyethyltrialkylammonium salts, salts of polyacrylic acid, carboxymethylcellulose, vinyl alcohol-acrylic salt copolymers, iobutylenemaleic anhydride copolymers, and starch-acrylic acid graft copolymers. These highly water-absorptive resins, are each a crosslinked polyelectrolyte containing a halogen ion, an alkali metal ion, an I t. ammonium ion, or the like as the counter ion.

It is necessary to disperse the above-described water-absorptive resin in the soil in fine particle form. For this purpose, it is necessary that the grinding in a dry state or the shearing for kneading with hydrous soil provide a granule diameter of 2mm or less, preferably Imm or less in a hydrous state.

The highly water-absorptive resin is incorporated in an amount of 0.1 to 10% by weight based on the whole dry solid. Examples of the water-soluble organic polymer used in the present invention include a polymer having a limiting viscosity number of 0.2 to 20 dt/g as determined in 1 N salt solution 6 I f and selected from among salts of polyacrylic acid, polyacrylamide (partial hydrolyzate thereof) and polyvinyl alcohol. The water-soluble organic polymer is added and mixed in an amount of 0.1 to 10% by weight based on the whole dry solid. It is convenient to mix the water-soluble organic polymer in powdery form with the soil when the soil particles are dry.

On the other hand, when the solid particles are hydrous, it is necessary to add the water-soluble 4 410 organic polymer in the form of an aaueous solution or a dispersion. The aaueous solution and the dispersion are preferably added to the hydrous solid and kneaded therewith in such a state that the viscosity is as low as 10000 cP or less. After being o o15 mixed with the clay particles, the water-soluble organic polymer may be insolubilized through a crosslinking reaction such as neturalization of electric charges, formalization, or the like. The order of addition of the water-soluble organic polymer and the highly water-absorptive resin is arbitrary, and they may be added simultaneously.

When the water-soluble organic polymer and the highly water-absorptive resin are to be added simultaneously, the water-absorptive resin may be preliminarily mixed with the water-soluble organic 7 '7 polymer, and it is also possible to use a highly water-absorptive resin containing a water-soluble organic polymer. The hydrous soil containing a highly water-absorptive resin and a water-soluble organic polymer is granulated into a sphere or a pellet having a diameter of 1 to 10mm. The hydrous 0 clay is air dried or heat dried to have a water content of 20% or less, preferably 10% or less, thereby preparing a solid granule. In the preparation i0 of a granular culture soil according to the present invention, a fertilizer, humus, etc. can be easily added to the granular soil. Further, it is also possible to incorporate coarse materials, such as sand or coal, as far as the resultant mixture falls 9 within the category of clay soil (clay content: at o least When it is difficult to granulate the hydrous clay because of its high water content during addition of the resin, it is preferred to dehydrate the hydrous clay by filtration or the like to regulate the water content.

EXAMPLE

The method of preparing a granular culture soil according to the present invention will now be described in more detail with reference to the following Examples.

8 Synthesis Example 1 A 500-m capped glass container equipped with a nitrogen inlet tube was charged with 200g of desalted water and 50g of acrylic acid. 25g of sodium hydroxide was dissolved therein while cooling the solution at 0 C, and 2mZ of a 1% aqueous methylenebisacrylamide solution was added thereto. Then, 25g of polysodium ,00 acrylate having a limiting viscosity number of 0.38dZ/g o O0 .e as determined in 1 N salt solution was added thereto 0o o .o.10 to prepare a monomer solution. The monomer solution 0 0 was subjected to nitrogen aeration, and 3mk of a aqueous ammonium persulfate solution and lmZ of a aqueous sodium hydrogensulfite solution were added o a thereto under conditions of a dissolved oxygen o0 015 concentration of 0.15ppm and a solution temperature of 25 0 C. The mixture was allowed to stand under 04 o adiabatic conditions for 24 hr to conduct polymerization.

The formed polymer was ground with a meat chopper and the powders were air dried at 105°C and then sieved to prepare 30- to 50-mesh particles of a highly waterabsorptive resin. This was designated as waterabsorptive resin A. The water absorption ratio of water-absorptive resin A was 320 as determined in purified water.

Synthesis Example 2

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t q# a 0O The container used in Synthesis Example 1, i.e., a. 500-m capped glass container equipped with a nitrogen inlet tube was charged with 200g of desalted water and 50g of acrylic acid. 25g of sodium hydroxide was dissolved therein while cooling the solution at 0 C, and 2mZ of a 1% aqueous methylenebisacrylamide solution was added thereto to prepare a monomer solution. The monomer solution was subjected to S nitrogen aeration, and 3m) of a 5% aqueous ammonium persulfate solution and Im£ of a 5% aqueous sodium 0 hydrogensulfite solution were added thereto under 0 conditions of a dissolved oxygen concentration of 0.15ppm and a solution temperature of 25 0 C. The mixture was allowed to stand under adiabatic conditions o 15 for 24 hr to conduct polymerization. The formed a polymer was ground with a meat chopper and the powders were.air dried at 105 0 C. and then sieved to prepare to 50-mesh particles of a highly water-absorptive resin. This resin was designated as water-absorptive resin B. The water absorption ratio of water-absorptive resin B was 560 as determined in purified water.

Synthesis Example 3 A l-Z four-necked separable flask equipped with an agitating device, a thermometer, a reflux condenser, and a nitrogen inlet tube was charged with 300g of a 'aq o o0 a a 41 'i :1: aI *P i~ A1: 10 i medium oil (a specific gravity of 0.83 and a flashing point of 138 0 30g of sorbitan monooleate and 0.3 g of 2,2'-azobisisobutyronitrile were added and dissolved therein at room temperature. Separately, 133g of acrylamide and 16 7 g of ammonium acrylate were dissolved in 325g of ion-exchanged water to prepare a monomer solution. The monomer solution was put into the aboveo r described separable flask and agitated.

The mixture was purged with nitrogen for 30 min, and polymerization was conducted for 5 hr while o maintaining the internal temperature at 600C.

of polyoxyethylene sorbitan trioleate was added to the resultant emulsion to prepare a solution.

o t This solution was designated as water-soluble resin C.

oa ,15 The polymer of water-soluble resin C had a limiting S, riscosity number of 12.8dt/g at 25°C as determined in 1 N salt solution.

Example 1 s 20kg of a dried clay powder was mixed in powdery form with water-absorptive resin A in an amount shown in Table 1, and 12kg of water was added thereto. The mixture was kneaded with a mortar mixture was granulated to prepare a granulated soil. The granulated soil was air dried at 105°C to prepare a granular culture soil having a water content of 10% or less. The water 11- I t ,I results shown in Table 1. The water retention was measured by the following method.

A 1000-fold diluted solution of a liauid fertilizer (having a N content of a P 2 0 5 content of 10%, and a K20 content of was added in such ooo an amount that all the granules were immersed therein.

The mixture was allowed to stand for 1 hr and centrio"o fuged at 100 G for 10 min, and the water retention S" 0 was determined from the loss on drying per 100g of the dry solid.

Table 1 a a 0 15 0 0 Amount of addition Water ampe N. of water-absorptive retention resin (g) sample 1 200 59 sample 2 300 71 sample 3 400 79 sample 4 600 87 Example 2 400g of hydrous clay having a dry solid content of 75% was placed in a vinyl bag, and water-absorptive resin B dispersed in 200g of water was added thereto in an amount shown in Table 2. The mixture was kneaded by hand. Then, water-soluble resin C in an -12: 12 amount corresponding to the amount of the polymer shown in Table 2 was added in emulsion form, and the mixture was kneaded by hand. The hydrous soil was extruded through a hole having a diameter of 3.5mm to prepare a pelletized soil having a length of about 5mm. The pelletized soil was air dried at 105 0 C to prepare a granular culture soil having a water content of 10% or less. The obtained soil was subjected to measurement of the water retention.

0 0 0 The results are shown in Table 2.

0 0 13 amoun corresponding to the- ;fn amutofteplye sh w in Tabl 2 wasii adde in emulsion: fo m an .thmitre wa naedb ad Tehdos ol l wasextude thoug a olehavng dimetr o I Ir -,i s .1 0h 0eut 0r ,hw .'*ale2 f 0^ 9 i p 1 1 1 1 1 13 I

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Table 2 6 .q 0 0

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Sample Amount of addition lAmount of addition. Water Samp. of water-absorptiveiof water-soluble retention N.resin B resin C (g) sam-p1e 5 10 1 77 sample 6 10 2 s ampl1e 7 10 15 82 Isampole 8 10 10 81 sample 9 5 1 s amTpl1e 10 5 2 74 sampole 11 5 5 sample 12 5 10 T 78 sample 13, 1 2 37 sample 14! 1 j5 42 sample 151 1 10 comp.

sample 1 0 5 19 comp.

sample 2 0 .2 comp.

sample 3 5 0 disintegrated comp.

sample 4 0 0 disintegrae 4 .14 an easily soluble powdery soil aggregating agent Ib- I The granular culture soil prepared by the method of the present invention was subjected to a cultivation test. The results were as follows.

Polyethylene pots were respectively packed with samples prepared in the above-described Examples.

Three pieces of Brassica campestris L. var.

perviridis in a two-foliate stage in the main leaf were transplanted to each pot and subject to a cultivation test.

10 A 1000-fold diluted solution of a liquid to fertilizer (having a N content of a P0 5 content 2 5 of 10%, and a K20 content of was sprinkled on the plants every two days. 40 days after the initiation of the test, the weight of the plant at '15 the aerial part and that at the underground part were measured. The average weight value of each part per plant of each sample is shown in Table 3.

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Table 3 It 4 1 I 4 4444 41 1 4 4 1 t tI #114 I I 1111 10 4 Sample No. fWeight at aerial Weight at underground part part (g) sample 1 45.7 4.65 sample 2 48.5 4.37 sample 3 53.2 5.91 sample 4 56.7 5.27 sample 5 50.5 5.24 sample 6 48.3 5.11 sample 749.5 5.31 sample 8 52.3 5.35 sample 9 38.6 4.31 sample 10 40.3 4.35 sample 11 44.0 4.40 sample 12 41.2 4.95 sample 13 30.2 3.24 sample 14 33.1 3.59 sample 15 32.5 3.71 comp.

sample 1 14.7 1.34 comp.

sample 2 16.9 1.56 comp.

sample 3 blasted blasted comp.

sample 4 blasted blasted 4 4 *4 4 I 44 4 4 4 '15 'Itt I I I 41 16 Ii W

Claims (19)

1. A method of preparing a granular culture soil which comprises adding to a hydrous soil 0.1 to 10% by weight, based on the whole dry solid, of a highly water-absorptive resin and 0.1 to 10% by weight, based on the whole dry solid, of a water-soluble organic polymer, kneading the mixture, granulating the resultant hydrous soil containing the highly water-absorptive resin and water-soluble organic polymer and drying the formed granules.

2. A method of preparing a granular culture soil according to claim 1, wherein said highly water-absorptive resin has a water absorption ratio of at °o least 100 as determined in purified water.

3. A method of preparing a granular culture soil according to claim 1, wherein said water-soluble organic polymer has a limiting viscosity number of 0.2 to °a °a as determined in 1 N salt solution. a-

4. A method of preparing a granular culture soil according to claim 1, wherein said soil as a raw material contains fine soil particles having a diameter of 0.01mm a or less in an amount of at least 50% by weight based on the whole soil component in a dry state.

A method of preparing a granular culture soil according to claim 1, wherein drying is conducted after said hydrous soil is granulated into a sphere or a pellet having a particle diameter of 1 to 17

6. A method of preparing a granular culture soil according to claim 1, wherein said highly water- absorptive resin contains said water-soluble organic polymer.

7. A method of preparing a granular culture soil according to claim 1, wherein said hydrous soil is kneaded with said water-soluble organic polymer by adding said water-soluble organic polymer in the 4rf t r form of a solution having a viscosity as low as 10000 cP or less.

8. A method of preparing a granular culture soil a° according to claim 1, wherein said highly water- absorptive resin is a crosslinked polymer comprising a member selected from among poly(meth)acryloyloxy- ooee Sethyltrialkylammonium salts, salts of polyacrylic acid, carboxymethylcellulose, vinyl alcohol-acrylic S0:t salt copolymers, salts of isobutylene-maleic anhydride copolymers, salts of starch-acrylic acid graft copolymers, and mixtures thereof. 0 4

9. A method of preparing a granular culture soil according to claim 1, wherein said highly water- absorptive resin is a crosslinked poly(meth)acryloyloxy- ethyltrialkylammonium salt.

A method of preparing a granular culture soil according to claim 1, wherein said highly water- 18 '*Fr i i 1 I absorptive resin is a crosslinked salt. of polyacrylic acid.

11. A method of preparing a granular culture soil according to claim 1, wherein said highly water- absorptive resin is crosslinked carboxymethylcellulose.

12. A method of preparing a granular culture soil according to claim 1, wherein said highly water- absorptive resin is a vinyl alcohol-acrylic salt copolymer. i,

13. A method of preparing a granular culture soil Sia S according to claim 1, wherein said highly water- absorptive resin is a. salt of an isobutylene-maleic anhydride copolymer.

14. A method of preparing a granular culture soil according to claim 1, wherein said highly water- a, absorptive resin is a salt of a starch-acrylic acid copolymer.

I A method of preparing a granular culture soil according to claim 1, wherein said water-soluble organic polymer is a member selected from among salts of polyacrylic acid, polyacrylamide (partial hydrolyzate thereof), polyvinyl alcohol, and mixtures thereof.

16. A method of preparing a granular culture soil according to claim 1, wherein said water-soluble 19 preliminarily mixed with the water-soluble organic 7 I: II liii:( 1A-_ V organic polymer is a salt of polyacrylic acid.

17. A method of preparing a granular culture soil according to claim 1, wherein said water-soluble organic polymer is polyacrylamide (partial hydrolyzate thereof).

18.. A method of preparing a granular culture soil according to claim 1, wherein said water-soluble organic polymer is polyvinyl alcohol.

19. A method of preparing a granula culture soil substantially as herein described with reference to any one of the examples. DATED this 1st Day of September, 1989 KYORITSU YUKI CO., LTD. and RIHACHI SHIRAI Attorney: IAN ERNST Fellow Institute of Patent Attorneys of Australia of SHELSTON WATERS 0 0 0 00B 0 01 0 0 0 )0 0q 0 0 0* 0 (0 0 0 00.. 00 20 ;:i