JP2011251860A - Granular organic fertilizer and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a granular organic compound fertilizer having sufficient physical and chemical properties to endure mechanical fertilizing etc., while it is mainly made from steamed leather powder as a raw material at a low cost by making it possible to compound the steamed leather powder as a raw material of the granular organic compound fertilizer much higher than current use (30-40% to the total raw material).SOLUTION: This granular organic fertilizer is manufactured by mixing 50-75 wt.% steamed leather powder, 15-48 wt.% organic fertilizer and 2-10 wt.% granulation accelerator, granulating and drying. The steamed leather powder has bulk specific gravity of not smaller than 0.8 and a maximum water content of not higher than 450 wt.%.

Description

  The present invention relates to a granular organic fertilizer and a method for producing the same, and more particularly to a granular organic fertilizer mainly using steamed leather powder, which is a low-cost, high-protein organic raw material, and a method for producing the same.

  Due to consumer demand for safe and secure crops, crop production using fertilizers mainly composed of organic fertilizers such as organic farm products and specially grown farm products is increasing. In addition, granular compound fertilizer factories that have been adopted as production methods for low-cost compound fertilizers also require low-cost granular organic fertilizers that possess physicochemical properties that match compounding suitability as raw materials for organic-containing compound fertilizers. Yes. With regard to such organic fertilizers, the present applicant has already made many proposals (for example, Patent Document 1).

  On the other hand, regarding organic raw materials, import restrictions on livestock-related products due to the occurrence of overseas livestock diseases such as BSE and poultry influenza, increased demand for fuel for cereal products such as bioethanol, and cereal foods in China and developing countries Due to the increase in demand for feed raw materials due to the shift from livestock to livestock products, organic raw materials for fertilizers are particularly tight.

  Under such circumstances, steamed leather powder, one of animal organic raw materials, is produced from leather scraps in the leather industry and is not used for feed. It is evaluated as a fertilizer. The present applicant also exemplifies the use of steamed leather powder as a raw material in the production of a granular compound fertilizer (for example, Patent Document 2).

  However, steamed leather powder is a fibrous protein, so it lacks pulverization and agglomeration and is difficult to use as a raw material for granular organic fertilizers. Therefore, it was recognized that 30 to 40% of the total amount of raw materials was the use limit.

JP-A-3-237084 JP 2007-290948 A

  Therefore, this invention has been conventionally recognized as a steaming that has been recognized as the use limit of 30 to 40% of the total raw materials due to the granulation properties required for the granular organic fertilizer and the constraints of ensuring the physical properties of the product. Granular organic composite with sufficient physicochemical properties that can withstand mechanical fertilization, etc., while allowing leather powder to be blended and used more as a raw material for granular organic composite fertilizer than ever before The purpose is to provide fertilizer at low cost.

The invention according to claim 1 of the present application is
It is a granular organic fertilizer obtained by mixing 50 to 75% by weight of steamed leather powder, 15 to 48% by weight of organic fertilizer and 2 to 10% by weight of a granulation accelerator, granulating and drying.

The invention according to claim 2
2. The granular organic fertilizer according to claim 1, wherein the steamed leather powder has a bulk specific gravity of 0.8 or more and a maximum water capacity of 450% by weight or less.

The invention described in claim 3
3. The steamed leather powder, the organic fertilizer, and the granulation accelerator are mixed and then pulverized to adjust the particle size to 40% or more and 70% or less at a passage rate of 500 microns, and then granulated. Of granular organic fertilizer.

The invention according to claim 4
The granular organic fertilizer according to any one of claims 1 to 3, wherein the total amount of nitrogen is 9% or more.

The invention according to claim 5
It is the manufacturing method of the granular organic fertilizer which mixes 50-75 weight% of steamed leather powder, 15-48 weight% of organic fertilizer, and 2-10 weight% of granulation promoters, and performs granulation and drying.

The invention described in claim 6
6. The method for producing a granular organic fertilizer according to claim 5, wherein the steamed leather powder has a bulk specific gravity of 0.8 or more and a maximum water capacity of 450% by weight or less.

The invention described in claim 7
7. The steamed leather powder, the organic fertilizer and the granulation accelerator are mixed and then pulverized to adjust the particle size to 40% or more and 70% or less at a passage rate of 500 microns, and then granulated. This is a method for producing granular organic fertilizer.

The invention described in claim 8
The method for producing a granular organic fertilizer according to any one of claims 5 to 7, wherein a kneading step is performed before the granulation step and granulation is performed at a moisture content of 35% or less.

The invention according to claim 9
The granular organic fertilizer according to any one of claims 5 to 8, wherein a granulating step is combined with a granulating step comprising high-speed rolling sizing or pulverizing rolling sizing.

  According to this invention, from the past, the granulation required for granular organic fertilizer and the restriction of securing the physical properties of the product, steaming that was recognized as 30 to 40% of the total raw material was the use limit Granular organic composite with sufficient physicochemical properties that can withstand mechanical fertilization, etc., while allowing leather powder to be blended and used more as a raw material for granular organic composite fertilizer than ever before Fertilizer can be provided at low cost.

The flowchart explaining the outline process of an example of the manufacturing method of this invention.

  In the present invention, 50 to 75% by weight of steamed leather powder, 15 to 48% by weight of organic fertilizer and 2 to 10% by weight of granulation accelerator are mixed, and granulated and dried to produce a granular organic fertilizer. To do.

  Conventionally, steamed leather powder has been evaluated as a low-cost organic fertilizer with high protein (high nitrogen content). However, since it is a fibrous protein, it lacks pulverization and cohesion, is difficult to use as a raw material for granular organic fertilizer, and is a steamed leather due to the granulation properties required for granular organic fertilizer and the restrictions on securing physical properties of products. It was recognized that the blending of 30 to 40% of the powder was the use limit with respect to the whole raw material. In the present invention, a granular organic fertilizer is produced by blending steamed leather powder in an amount of 50 to 75% by weight of the raw material. Thereby, a high-component granular organic composite fertilizer can be provided.

  The granular organic fertilizer of the present invention is an organic composite fertilizer that is granulated by mixing organic fertilizers according to the fertilizer control method, and falls under the category of mixed organic fertilizers under the fertilizer control method. Therefore, any organic fertilizer to be blended in the above can be used as long as it is defined in the official standard as a normal fertilizer based on the Fertilizer Control Law.

  The steamed leather powder used in the present invention is “pulverized by pressurizing and digesting leather scraps discarded from a leather factory and a leather processor” (from the explanation of fertilizer terms in the “Pocket Fertilizer Manual”). Steamed leather powder with tannin and chrome tanning can be produced by tanning the raw leather. Tannin tanned products contain 6.0-7.5% nitrogen, and chrome tanned products contain 11.0-12.5% nitrogen and are usually referred to as skin powder (kawako).

  If the content of steamed leather powder is less than 50% by weight of the raw material used, the cost reduction effect due to the use of the skin powder is not sufficient (it could be used if it was 30-40% so far), and a high nitrogen component cannot be secured. So undesirable. On the other hand, if it exceeds 75% by weight, the amount of water added to give cohesive force increases, resulting in a decrease in productivity, energy cost, etc., and the cost improvement effect becomes insufficient, which is not desirable.

  In the above, the blending ratio of the binder is set to 2% by weight or more from the viewpoint that it is difficult to secure the raw material binding force when the content is less than this, and 10% by weight or less is the fertilizer. This is because it is difficult to secure the components and the cost is increased.

  The type of binder to be used is not particularly limited as long as it is a general binder used for organic fertilizers containing organic matter. As an example, clay minerals such as starch or pregelatinized starch, lignin, bentonite and zeolite, and konjac powder produced as a by-product when konjac flour is pulverized can be used.

  In the above, it is desirable to select and use steamed leather powder having a bulk specific gravity of 0.8 or more and a maximum water capacity of 450% by weight or less.

  Steamed leather powder is produced under various processing conditions. Therefore, even if it is in the market as steamed leather powder, there are differences in its physical properties.

  In normal skin powder, shaving scraps generated in the tanning process are preferably used because of the stability of the components and the suitability for processing in the steaming process. However, the physical properties are soft and light in specific gravity like a sponge. Therefore, a large amount of water is generally required to impart cohesive force. For this reason, as a general tendency, steamed leather powder after steaming has low bulk specific gravity and high water retention.

  The inventors of the present application classify steamed leather powder obtained from each production factory distributed in the market in terms of physical properties and conduct a granulation test, so that those with high specific gravity and low water retention are granular processing Has been found to be advantageous. And, by using steamed leather powder showing specific physical properties, it is possible to provide a granular organic composite fertilizer with sufficient physicochemical properties that can withstand mechanical fertilization while using steamed leather powder as the main ingredient. This was confirmed and the present invention was completed.

  As described above, this specific physical property is 0.8 or more in bulk specific gravity and 450 or less in maximum water content% used in soil analysis.

  If the bulk specific gravity is less than 0.8, the cohesiveness and stickiness are weakened, so that the product hardness is lowered and the powdering rate is increased. For this reason, since it becomes impossible to ensure physical properties required as a granular organic fertilizer, it is not preferable.

  On the other hand, when the maximum water volume exceeds 450% by weight, the water absorption capacity of the raw material is increased, so that granulated moisture for imparting cohesiveness is increased, and the energy cost is increased in the drying step, which is not desirable.

  In the present invention, the bulk specific gravity is measured three times by putting about 400 g of a sample into a 500 mL measuring cylinder, tapping the bottom of the measuring cylinder lightly three times, reading the volume with a scale, and measuring the weight with an automatic balance. By seeking the average.

  In the present invention, the maximum water content% is measured in the following manner according to the Hilgard method used in soil measurement. Make a hole in the bottom of the container, fill the container with the steamed leather powder to be evaluated (absolutely dried product), let it water naturally from the bottom, and check that the steamed leather powder filled in the container is evenly fed, 30 minutes It is allowed to stand for sufficient water supply, and the ratio between the amount of water supply and the steamed leather powder (an absolute dry product) to be evaluated is determined.

  The raw materials of the above blending are mixed and then granulated while appropriately adding water. As shown in the schematic process diagram of FIG. 1, steamed leather powder, organic fertilizer, and granulation accelerator are mixed and then pulverized. Then, it is desirable to granulate after adjusting the particle size to 40% or more and 70% or less at a passage rate of 500 microns.

  As a result of further investigation by the invention of the present application, it was recognized that it is more advantageous to granulate the granular organic fertilizer of the present invention under specific conditions in the production process. One of these specific conditions is that the mixed steamed leather powder, organic fertilizer and granulation accelerator are pulverized before the granulation step, and the particle size is adjusted to 40% or more and 70% or less at a passage rate of 500 microns. It is.

  If the passing rate of 500 microns is less than 40%, the binding force of the raw material particles is weakened, the yield and productivity are lowered, and the cost is deteriorated. Further, in terms of quality, it is not desirable because it becomes difficult to ensure the quality necessary for the granular organic fertilizer, such as a decrease in hardness and an increase in the powdering rate.

  On the other hand, if it is higher than 70% at a passage rate of 500 microns, the water holding power is increased, the water suitable for granulation is increased, and the drying cost is deteriorated. In addition, the hardness of the granular product before drying is lowered, and powdering in the drying process is increased, which may reduce productivity and increase costs. Further, the product quality is not desirable because hardness may decrease.

  Nara type, hammer mill, Raymond mill, pulverizer, etc. are used as pulverizers for pulverizing the blended raw materials mixed as described above and adjusting the particle size of the pulverized product to 40% or more and 70% or less at a passage rate of 500 microns A commonly used crusher can be used and is not particularly limited.

  In the present invention, after mixing the above-described blended raw materials, or after pulverization and particle size adjustment after mixing as described above, granulation is performed as described in the schematic steps in FIG.

  In the granulation process, water is added to the raw material, and it is rolled with a drum granulator or the like to make use of the viscosity of the raw material to form particles having a particle diameter of about 1 to 6 mm. The granulation method is not particularly limited, and any of rolling type, extrusion granulation, and compression granulation can be used.

  At this time, it is desirable to granulate with a moisture content of 35% or less in consideration of the energy cost in the subsequent drying step.

  Moreover, when granulating, as shown in the schematic process of FIG. 1, when kneading as a pretreatment, viscosity adjustment such as increasing the viscosity can be performed, thereby improving the moldability and promoting granulation. This is advantageous because it can improve the productivity and the granulation yield, and can improve the product quality.

  The kneading method is not particularly limited as long as it is a device that gives a kneading effect to the organic raw material, and a kneader, a wheel-type kneader, a pug mixer, or the like can be used.

  In addition, the physical property value (physicochemical property) calculated | required with a general granular fertilizer is the particle size 2-4mm 95% or more, hardness 1kgf or more, a powdering rate 1.0 %% or less, an angle of repose 38 degrees or less, There is no caking property.

  In this application, by satisfying these physical property values (physicochemical properties), it is a granular organic fertilizer that can be used as a raw material for mechanical fertilization and granular compound fertilizer as well as general granular fertilizer, and has high quality At low cost.

  Therefore, as described above, granulation is performed at a moisture content of 35% or less, preferably granulation at a moisture content of 35% or less after the kneading step to improve product quality (hardness of 1 kgf or more, powdering rate of 1.0%). % Or less) is desirable.

  In addition, from the viewpoint of improving product quality (mechanical fertilization characteristics), combining granulation processes after granulation processes such as compression granulation / disintegration rolling sizing, wet extrusion granulation / high speed rolling sizing, etc. preferable.

  After the granulation step, if necessary, the granulated organic fertilizer of the present invention can be produced by sizing and then drying as shown in the schematic step of FIG.

  The granular organic fertilizer produced by drying is cooled, sieved, packaged and shipped as shown in the schematic process of FIG. In sieving, the particle size is adjusted to 2 to 4 mm with a sieving machine.

  In the drying step, the granulated product is dried to a moisture content of 5% or less. For example, a conventionally known thermal power dryer can be used for drying. By controlling the moisture content to 5% or less, it is possible to prevent the occurrence of mold, etc., and ensure physical hardness, to ensure physical properties such as alteration during storage, fluidity during mechanical fertilization, and prevention of powdering. .

  According to the present invention, 50 to 75% by weight of high-protein (high nitrogen component content) steamed leather powder is blended in the raw material component, so that the high-component (9% or more of the total amount of nitrogen) It is possible to provide a granular organic fertilizer having fertilization characteristics (product quality, hardness of 1 kgf or more, powdering rate of 1.0% or less).

  According to a study by the inventors, in the present invention in which steamed leather powder is blended in the raw material components in an amount of 50 to 75% by weight, the total amount of nitrogen is 9% or more, and the total amount of phosphoric acid is 1% or more. Granular organic fertilizer could be produced.

  In the present invention, the total amount of nitrogen (TN) and the total amount of phosphoric acid (TP) are guaranteed components described in the official standards for ordinary fertilizer based on the Fertilizer Control Law, and the fertilizer analysis method (reference material 1: Calculated by the quantitative method described in Agricultural Environmental Technology Research Institute, Ministry of Agriculture, Forestry and Fisheries, Japan Fertilizer Examination Association, 4.1.1 Total amount of nitrogen, 4.2.3 Total amount of phosphoric acid).

  When the bulk specific gravity and the maximum water content% were measured in the manner described above for commercially available steamed leather powder (using chrome-tanned steamed leather powder), as described in the normal skin powder column of Table 1. The bulk specific gravity was 0.7, and the maximum water capacity was 595% by weight. This was used as a comparative product in the raw material.

Next, the bulk specific gravity and the maximum water volume were measured as described above for the commercially available steamed leather powder (using chrome-tanned steamed leather powder), the bulk specific gravity was 0.8 or more, and the maximum water volume was 450% by weight. When the following were selected, as described in the column of selected skin powder in Table 1, one having a bulk specific gravity of 0.82 and a maximum water content of 424% by weight can be selected. Used as raw material to produce organic fertilizer.

  Oil cake, steamed hair flour, by-product vegetable fertilizer, fungus body fertilizer, and bone powder were used as organic fertilizers, and konjac flying powder was used as a binder.

Each raw material is weighed as shown in the schematic diagram of the manufacturing process of FIG. 1, and is blended so that the total proportion is 5 kg in the blending ratio (% by weight) shown in Table 2. Designed to be at least%.

  After mixing the blended raw materials, the entire amount was passed through a Nara type pulverizer and pulverized. The pulverized particle size is as shown in Table 3.

  Next, without passing through the kneading step, the blended raw materials were put into a dish-type granulator (diameter 1 m, 21 rpm), and sprayed with water while confirming the granulation status with a power sprayer, and granulated.

  Next, after drying for 3 hours with hot air at 80 degrees in a ventilation shelf dryer, the granular product is measured for 2 to 4 mm granulation yield using a 2 mm and 4 mm sieve, and the hardness of the product is measured by a Kiyama hardness tester. Measured with

  In the present invention, the hardness is obtained by measuring the hardness of 15 grains with a Kiyama hardness tester and calculating the average.

The results are shown in Table 3.

<Bulk specific gravity, maximum water volume (% by weight)>
From the results shown in Table 3, in the case where normal skin powder having a bulk specific gravity of 0.7 and a maximum water volume of 595% by weight was used (Test Nos. 1-1 to 1-3), the ratio of skin powder used to the product was In the case of 30% or less (Test No. 1-1), good granulation property was obtained, but in the case where the skin powder was used at 50% or more (Test No. 1-2 and Test No. 1-3), granulation was performed. The moisture content was as high as 48% or more, and the granulation yield and hardness were greatly reduced from the target values, and granulation was considered difficult.

    On the other hand, in the selected skin powder having a bulk specific gravity of 0.82 and a maximum water content of 424% by weight, the granulated water was slightly increased even when the skin powder was used at 50% or more (Test No. 1-4-1). The yield and hardness cleared the target values and could be granulated.

  As a result, when steamed leather powder having a bulk specific gravity of 0.7 and a maximum water volume of 595% by weight is used as the raw material, if the blending ratio exceeds 50%, the granulation yield and hardness greatly decrease the target value, Although granulation becomes difficult, it was confirmed that the steamed leather powder having a bulk specific gravity of 0.82 and a maximum water content of 424% by weight can be granulated even if the blending ratio to the raw material exceeds 50%.

<Grinding particle size>
In this example, the pulverization particle size is adjusted by the pulverizer passing speed, and the test No. The 1-4 district was adjusted to 3 stages.

    As shown in the results of Table 3, in the 1-4-2 district where the 500 micron passage ratio is as high as 76.0%, the granulation moisture increased due to the increased water retention amount, and the granulation yield was slightly improved. The grain after sizing became softer and the product hardness decreased.

    On the other hand, in the 1-4-3 section in which the crushed particle size was coarsely adjusted to 37.70% with a passage of 500 microns, the granulated moisture decreased due to the decrease in the water retention amount, but the grain size deteriorated, and the granulation Yield deteriorated. Moreover, the hardness also decreased.

    In light of other studies conducted by the inventors, it was recognized that the particle size adjustment was good at 40% or more and 70% or less at a 500 micron pass rate.

<Binder compounding ratio>
As a confirmation of the effect of the binder, an added group (Test No. 1-4-1) and an additive-free group (Test No. 1-5) were compared. If the binder is not added, the granulation property is deteriorated, and each target value is slightly deteriorated. It was confirmed that the binder is necessary for achieving the desired granulation property and product quality.

  When the bulk specific gravity and the maximum water volume were measured in the same manner as described above for two types of steamed leather powders that were marketed (both steamed leather powders of chrome tanning), they were listed in columns A and B of Table 4 for normal skin powders. As shown, the bulk specific gravity was 0.7 and the maximum water content was 599%, and the bulk specific gravity was 0.69 and the maximum water content was 483% by weight. These were used as raw materials for comparison.

Next, for the steamed leather powder commercially available, the bulk specific gravity and the maximum water volume were measured in the manner described above, and two kinds of those having a bulk specific gravity of 0.8 or more and a maximum water volume of 450 wt% or less (both of which were chromium) Tanned steamed leather powder) When selected, as shown in the selected skin powder columns C and D of Table 4, the bulk specific gravity is 0.82, the maximum water capacity is 431 wt%, and the bulk specific gravity is 0.82. Those having a maximum water capacity of 407% by weight can be selected and used as raw materials for producing the granular organic fertilizer of the present invention.

  Oil cake, steamed hair flour, by-product vegetable fertilizer, fungus body fertilizer, and bone powder were used as organic fertilizers, and konjac flying powder was used as a binder.

Each raw material was weighed as shown in the production process schematic diagram of FIG. 1 and blended so that the blending ratio (% by weight) in Table 5 was 7 kg in total. The total amount of nitrogen and the total amount of phosphoric acid were as shown in Table 5, respectively.

  After mixing the blended raw materials, the entire amount was passed through a Nara type pulverizer and pulverized. The pulverized particle size was adjusted by the pulverizer passing speed, and the 500 micron passing rate was adjusted to 60%. The actually measured pulverized particle sizes were as shown in Tables 6 and 7, respectively.

  Next, using a kneader, water was added appropriately while confirming the kneading situation, and kneading was performed for 2 minutes. Thereafter, granulation was performed, and the granulation moisture percentages were as shown in Tables 6 and 7, respectively.

  For granulation, all test sections were molded with a wet extrusion granulator and then sized with a granulator (Table 6). In addition, test No. About 2-1 and 2-3, after carrying out compression granulation with a briquette granulator, it granulated with the granulator (Table 7). Only the rolling granulation of the dish type method etc. employed in Example 1 relies on only water for cohesion of organic raw materials, and therefore, improvement of granulation by particle size adjustment and kneading was examined.

  Next, the granulated product was dried with hot air at 80 ° C. for 3 hours in a ventilation shelf dryer, and then the product yield of 2 to 4 mm was measured with a 2 mm and 4 mm sieve, and the product hardness was set in the same manner as Example 1 Measured with a hardness meter.

The results are shown in Tables 6 and 7.

    As shown in Table 6, when steamed leather powder having a bulk specific gravity of 0.8 or more and a maximum water volume of 450% or less is used as a raw material, the productivity and physical properties as granular fertilizer are used at a skin powder usage rate of 55 to 75%. It was confirmed that it could be secured.

  In this example and the present invention, the angle of repose and the powdering rate are measured as follows.

<Repose angle>
Measured with a three-wheel repose angle measuring instrument (manufactured by Tsutsui Riken). The measurement operation was performed twice to obtain an average value.

<Powdering rate>
The sample is sieved in advance with a 2.0 mm sieve to remove powder less than 2.0 mm. 250 g of sample from which powder less than 2.0 mm has been removed is placed in a 500 ml styrol stick bottle, covered, and shaken for 15 minutes with a reciprocating shaker (TAITEC's RECIPRO SHAKER SR-2W, shake setting: 300 min ⁻¹ ). I will. The sample after shaking is sieved again with a 2.0 mm sieve, and the ratio of the portion under the sieve is determined (% by weight).

  As shown in Table 7, test no. 2-1, test no. In both cases, the percentage of skin powder used was 55% by weight, but when steamed leather powder having a bulk specific gravity of 0.8 or more and a maximum water capacity of 450 or less was used as a raw material (Test No. 2-3) As a result, the product quality was able to achieve the target value. On the other hand, when the conditions of the bulk specific gravity and the maximum water capacity% were not satisfied (Test No. 2-1), granulation was impossible.

  That is, even when compression granulation is performed with a briquette granulator, when steamed leather powder having a bulk specific gravity of 0.8 or more and a maximum water capacity of 450 or less is used as a raw material, the skin powder usage rate is 55 to 75%. It was confirmed that productivity and physical properties as granular fertilizer can be secured.

    The preferred embodiments and examples of the present invention have been described above. However, the present invention is not limited to these embodiments and examples, and various modifications can be made within the technical scope grasped from the description of the claims. Is possible.

Claims (9)

  A granular organic fertilizer obtained by mixing 50 to 75% by weight of steamed leather powder, 15 to 48% by weight of organic fertilizer, and 2 to 10% by weight of a granulation accelerator, granulating and drying.   The granular organic fertilizer according to claim 1, wherein the steamed leather powder has a bulk specific gravity of 0.8 or more and a maximum water capacity of 450% by weight or less.   3. The steamed leather powder, the organic fertilizer, and the granulation accelerator are mixed and then pulverized to adjust the particle size to 40% or more and 70% or less at a passage rate of 500 microns, and then granulated. Granular organic fertilizer.   The granular organic fertilizer according to any one of claims 1 to 3, wherein the total amount of nitrogen is 9% or more.   A method for producing granular organic fertilizer in which 50 to 75% by weight of steamed leather powder, 15 to 48% by weight of organic fertilizer, and 2 to 10% by weight of a granulation accelerator are mixed and granulated and dried.   6. The method for producing a granular organic fertilizer according to claim 5, wherein the steamed leather powder has a bulk specific gravity of 0.8 or more and a maximum water capacity of 450% by weight or less.   7. The steamed leather powder, the organic fertilizer and the granulation accelerator are mixed and then pulverized to adjust the particle size to 40% or more and 70% or less at a passage rate of 500 microns, and then granulated. Production method of granular organic fertilizer.   The method for producing a granular organic fertilizer according to any one of claims 5 to 7, wherein a kneading step is performed before the granulation step and granulation is performed at a moisture content of 35% or less.   The granular organic fertilizer according to any one of claims 5 to 8, wherein a granulation step comprising high-speed rolling granulation or pulverization rolling granulation is combined after the granulation step.

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