JPS6237940B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a molded medium for growing seedlings and a method for producing the same. In detail, a PH adjuster, a binder consisting of polyvinyl acetate emulsion and a water-soluble polymer are added to crushed rice husks and rice husk charcoal, mineral fines or natural fiber fines are added as necessary, and the mixture is frozen and kneaded. The present invention relates to a culture medium suitable for raising paddy rice seedlings in boxes, which involves molding the rice in a box. Nowadays, with the spread of rice transplanters, the number of seedlings raised in seedling boxes has increased dramatically, and the amount of soil required to serve as bed soil for raising seedlings in such boxes has also increased rapidly. Such soil (hereinafter, soil consisting only of natural soil will be referred to as cultivation soil, and soil that has been artificially prepared will be referred to as culture medium) has contradictory properties such as rapid water permeability and good water retention. is required. Kanuma soil is known to have these properties as a natural culture soil, but it is a limited resource and large-scale extraction will lead to the destruction of nature. Furthermore, it takes a large amount of man-hours to collect natural soil, dry it, sieve it, put it into seedling boxes, equalize the pressure, and make the bed. Therefore, labor can be saved by supplying pre-formed soil and culture medium to farmers through a distribution process. The potting soil and culture medium for growing seedlings in boxes must have the ability to retain their shape to withstand handling during the distribution process, and be hard enough to easily disintegrate with watering during sowing. In general, soil with poor water permeability may cause seedling root rot, soil with poor water retention may cause poor seedling growth due to lack of moisture, and hard soil such as heavy clay soil may cause wear and tear on the planting claws of the rice transplanter. Invite. It has already been considered and known to use rice husk and rice husk charcoal, which are easily available and currently have little other utility value, as typical materials for seedling raising soil. It has been found that these can be sufficiently suitable as a seedling growing medium by pulverizing the rice husks to promote ripening, and by washing the rice husk charcoal with water to reduce its alkalinity. However, crushed rice husk and rice husk charcoal are very bulky and inconvenient to handle, and are not suitable for distribution as they are. Therefore, in order to obtain a medium for raising box seedlings from crushed rice husks and rice husk charcoal, it is necessary to mold them with a suitable binder. For example, the present applicant previously applied for patent application 50-
No. 139942 (Japanese Unexamined Patent Publication No. 52-65004) proposed a binder based on cornstarch, but it required heating during kneading, and water penetration did not occur even when the formed soil was irrigated. Disadvantages such as the long time required were recognized. As a result of various studies, the present inventors have found that by forming a polyvinyl acetate emulsion with a water-soluble polymer such as polyvinyl alcohol as a binder at room temperature, it has both good water permeability and water retention. It was acknowledged that the desired object could be obtained. That is, the present invention resides in a molded medium for growing seedlings made of rice husk and rice husk smoked charcoal as a base material, kneaded and molded with the addition of a PH regulator and a binder as described above, and a method for producing the same. Next, the present invention will be explained with reference to its preferred embodiments. In the present invention, first, from 20% or more to 80% by dry weight
% or less, preferably 40 to 60%, of crushed rice husks and 20% or more to 80% or less, preferably 40 to 60% of rice husk charcoal by dry weight, and add a PH adjuster to the mixture to adjust the PH of the mixture to 4.
~7, preferably adjusted to 5~ ^5.5 is used as a base material, and a binder is added thereto in an amount of 5% or more and 60% or less, preferably 10 to 20% by dry weight, and if necessary, 50% or less. , preferably 10 to 20% mineral fines and/or natural fibrous fines. These mixtures are kneaded at room temperature, a specified amount is weighed out, put into a mold, leveled and compressed, and then dried to obtain a molded medium for growing box seedlings. In practicing this invention, the use of the binder is of paramount importance. In addition to acting as a binder, water-soluble polymers also have the effect of imparting water-retention properties to the culture medium, but they generally have high water-swelling properties and impede water permeability when used in large quantities. On the other hand, vinyl acetate acts as a binder, but it does not have water-swellability, so it is necessary to use an appropriate amount, thereby obtaining a molded product with good water permeability. A suitable blending ratio of vinyl acetate and water-soluble polymer is 80:20 to 35:65. In particular, polyvinyl acetate mixed with polyvinyl alcohol, which is obtained by emulsion polymerization using polyvinyl alcohol as a protective colloid, has film-forming properties even at 2°C, and can be molded into a culture medium at room temperature without the need for adding plasticizers. obtain. When molding, care must be taken that if the mixture contains too much water, the binding effect of the vinyl acetate emulsion will not be sufficiently exerted.
Therefore, it is desirable to reduce the water content of the crushed rice husks and rice husk charcoal in advance. That is, if there is a large amount of water in the mixture, it will take a long time to dry after molding, and the molded product may crack during drying. Furthermore, when the raw material base material contains a large amount of water, the amount of air entrained in the kneaded material decreases, resulting in a hard molded product and a tendency to inhibit water permeability. The rice husks provided as a material in the present invention are usually 10 to 15
% moisture, and the bulk specific gravity in this state is approximately 0.1 g/ ^cm3 , but it is crushed to reduce the bulk specific gravity to approximately 0.1 g/cm3.
It is best to set it at 0.2g/ ^cm3 . Rice husk charcoal contains about 50% moisture, but when dried to a moisture content of 5 to 10%, the bulk specific gravity is about 0.2 g/cm ³ . That is, in the method of the present invention, the crushed rice husk has a moisture content of 10 to 15% and a bulk specific gravity of approximately 0.2 g/ ^cm3 , and the rice husk charcoal has a moisture content of 5%.
~10% and a bulk specific gravity of approximately 0.2 g/cm ³ is preferably used. This has the effect of minimizing the amount of water in the kneaded material. The water content in the mixture, including the binder, is preferably about 50%. In addition, as the pH adjuster used in the present invention, inorganic acids such as sulfuric acid and hydrochloric acid are most suitable, and the amount is 1 to 5% based on the crushed rice husk and rice husk charcoal mixture.
added. The addition of mineral fines or natural fibrous fines such as bentonite, diatomaceous earth, peat moss, or a suitable natural soil to the mixtures of the present invention promotes the wettability of the substrate with water; In addition to making kneading work easier, it has the effect of improving moldability and promoting the disintegration of molded products when watered. The fine mineral matter and natural fibers may be used in an amount of 50% or less, preferably 10 to 20%, based on the base material. The molded product is approximately 58cm long and 28cm wide, according to the specifications of the seedling box.
It is best to specify a thickness of 1 to 2 cm. Since the weight per molded product is desired to be about 1 kg or less, the bulk specific gravity is preferably 0.2 to 1.0 g/ ^cm3 .
It is defined as 0.3 to 0.6 g/cm ³ . In the present invention, no particular heating is required for kneading and molding. For drying, natural drying or hot air drying is appropriately employed. The molded product obtained according to the present invention is strong and can withstand handling during the distribution process, and when water is applied to the molded product, water immediately penetrates, and it is made of a material that can be easily disintegrated and has good water retention. It is. Therefore, sowing, liquid fertilizer, and water administration can be carried out rationally, and it is suitable for the growth of rice seedlings. The seedling growing medium molded product manufactured by the method of the present invention is suitable for planting with a rice transplanter after seedling raising, and is more resistant to abrasion and wear of planting nails than the standard growing soil used in the past. It is comparable. Next, examples of the present invention will be shown. Example 1 A base material was prepared by adding 60 g of crushed rice husk with a dry weight of 10% moisture and 40 g of dry weight of rice husk charcoal with a moisture of 10% as a base material, and 150 g of a sulfuric acid aqueous solution (containing 30 g of 1N sulfuric acid) was added and stirred. The mixture was placed in a kneading machine and kneaded for about 30 minutes. The pH after kneading was ^5.0 . To this, 42 parts by weight of a polyvinyl alcohol aqueous solution (30% solids) was added to 58 parts by weight of polyvinyl acetate emulsion (55% solids, vinyl acetate: polyvinyl alcohol = 52:3), which had been polymerized with polyvinyl alcohol as a protective colloid. A dry weight of ^12.5 g of the blended binder (approximately 44% solids) was weighed, added to the base material, and kneaded.
Moisture was calculated to be about 50% of the total mixture. Further, the dry weight ratio of vinyl acetate and polyvinyl alcohol is 32:68. The resulting mixture (approximately 4)
It is placed in a synthetic resin frame with a length of about 58 cm and a width of about 28 cm and a thickness of about
After uniformly compressing to 1.8 cm with a leveling board, the load is approximately 70
The pressure tightening was continued for about 15 minutes at g/cm ² . This was then dried at room temperature. The molded product had a bulk density of ^0.35 g/cm ³ and disintegrated when touched 30 seconds after watering. The seeds were sown and the germination and rice growth conditions were observed, and both were good. Example 2 The mixture was prepared in the same manner as in Example 1 and molded in a metal frame.
Thereafter, it was treated in the same manner as in Example 1. The disintegration and germination properties due to water were exactly the same as in Example 1. Example 3 The product was formulated and molded in the same manner as in Example 1, and dried at approximately 70° C. using a ventilation dryer, but the results were similar to those in Example 1. Examples 4 to 6, Comparative Examples 1 to 3 40g dry weight of crushed rice husks with a moisture content of approximately 10% and a moisture content of approximately 10%.
The base material was prepared by adding 60 g of dry weight of rice husk charcoal and 10 g of bentonite in dry weight, an aqueous sulfuric acid solution was added thereto, and the mixture was kneaded in a mulch machine equipped with a stirrer for about 15 minutes. To this was added ^12.5 g of the binder described in Example 1 on a dry weight basis and kneaded. By changing the amount of sulfuric acid, molded media with different PH values were obtained. The prescription is shown in Table 1.

[Table] The molding medium was evaluated using the following method. Finish condition: Appearance judgment Irrigation condition: Water permeated the entire area within 30 to 60 seconds after irrigation, and those that could be disintegrated and sown by finger touch were evaluated as good. Germination status: After sowing with water, the seeds were kept in a flannel at 30-32°C and 90% humidity for 3 days, and the germination status was observed. Good - Roots have grown to about 30-35 mm and buds have grown to 20 mm Poor - Roots have grown to about 20 mm and buds have grown to about 15 mm Poor - Roots have grown to less than 10 mm and buds have grown to less than 10 mm Growth status: Germinated Paddy rice was kept in the soil at 20°C and 65% for 2 days and grown at 20 to 30°C for 14 days.
(Irrigation and fertilization) Good: Two true leaves appeared. Poor: Two true leaves were incomplete. Poor: The true leaves did not develop properly. The results are shown in Table 2.

[Table] Unsatisfactory Examples 7 to 11 The same experiment as in Example 4 was conducted by changing the blending ratio. The compounding formula is shown in Table 3, and the test results for the molding base are shown in Table 4.

【table】

【table】

[Table] Growth status Good Good Good Good
Examples 12 to 20 Similar experiments were conducted in accordance with Example 4 with different formulations. The formulation is shown in Table 5, and the test results of the molding medium are shown in Table 6.

【table】

[Table] Examples 21 to 26 The same experiment as in Example 4 was conducted by changing the amount of binder. The formulation is shown in Table 7, and the test results of the molding medium are shown in Table 8.

【table】

[Table] Growth status - Good Good Good Good
good
Examples 27-28, Comparative Examples 4-5 Similar experiments were conducted according to Example 8, except that the content of the binder was changed. The amount of binder used was 12.5 parts by dry weight based on the base material. Polyvinyl acetate emulsion is 55% solids (vinyl acetate to polyvinyl alcohol = 52:3) polyvinyl alcohol aqueous solution is
It has a solid content of 30%. Table 9 shows the composition of the binder used and the experimental results.

[Table] N vs. polyvinyl alcohol

[Table] Good
Comparative Example 4 had slightly poor moldability and water seepage during irrigation.
60 seconds was insufficient and some of the binder was observed to be washed away by watering and fertilizing. Comparative Example 5 had good moldability, but was a little too hard, had poor water permeation, and the germinated roots did not penetrate smoothly into the soil, resulting in a "root floating" phenomenon.

Claims (1)

[Scope of Claims] 1. Rice husk and rice husk smoky charcoal are used as a base material, and a PH adjuster is added thereto to adjust the pH to 4 to 7, and polyvinyl acetate emulsion and a water-soluble polymer are used as a base material, each of which has a dry weight of 5 to 60 parts of binder to 100 parts of base material (dry weight) in a ratio of 80:20 to 35:65.
part (dry weight), kneaded, and molded. 2 Rice husk and rice husk smoky charcoal are used as a base material, and a PH adjuster is added to this to adjust the pH to 4 to 7, and a polyvinyl acetate emulsion and a water-soluble polymer are used in a dry weight ratio of 80:20 to 20. 35:65 binder to 100 parts (dry weight) of base material 5 to 60 parts of binder
50 parts (dry weight) and further add not more than 50 parts of fine mineral matter or fine natural fiber, knead and mold the product.