Fertilizer and its manufacturing method

Abstract

We propose a fertilizer made of ureaformaldehyde, with regulated fertilizer release, suppressed initial release, and exhibiting a fertilizer release close to linear, as well as a method for producing the same fertilizer. [Solution] A fertilizer obtained by drying a ureas slurry consisting of urea and formaldehyde, which has a viscosity in the range of 0.01 to 0.60 (Pa·s, 23℃) and a molar ratio (U / F ratio) of urea to formaldehyde in the range of 0.5 to less than 1.0, in a drying step of 10 minutes or less. A fertilizer manufacturing method comprising a ureas slurry preparation step of preparing a ureas slurry consisting of urea and formaldehyde, which has a viscosity in the range of 0.01 to 0.60 (Pa·s, 23℃) and a molar ratio (U / F ratio) of urea to formaldehyde in the range of 0.5 to less than 1.0, and a drying step of drying the ureas slurry prepared in the ureas slurry preparation step in a drying step of 10 minutes or less.

Description

Technical Field

[0001] The present invention relates to a slow-release fertilizer, and more particularly to a slow-release fertilizer made of ureaform and having its fertilizer effect regulated so as to exhibit a fertilizer effect close to a linear type, and a method for producing the same.

Background Art

[0002] Today's agriculture faces various problems. For example, there are demands for labor saving in topdressing due to the aging of agricultural producers, demands for large-scale agricultural production by promoting cost reduction in production and corporate management of agriculture, and demands for improving fertilization efficiency in view of soil degradation caused by over-fertilization.

[0003] From these, labor-saving fertilization is demanded, the demand for slow-release fertilizers is increasing, and various proposals have been made.

[0004] Patent Document 1 discloses a slowly dissociating fertilizer composition composed of a urea-formaldehyde resin and a lignosulfonate, which is produced by spray-drying an aqueous mixture of the urea-formaldehyde resin and the lignosulfonate.

[0005] Patent Document 2 discloses a slow-release paste fertilizer having a high slow-release nitrogen content rate, which is synthesized by synthesizing ureaform in a solution of a soluble protein.

[0006] Patent Document 3 proposes a slow-release nitrogen fertilizer in which salts of metals such as copper, zinc, cobalt, nickel, manganese and silver are blended in a microbially decomposable slow-release nitrogen fertilizer.

[0007] Patent Document 4 discloses a sustained-release granular urea-formaldehyde polymer and a granular fertilizer produced using the granular urea-formaldehyde polymer.

[0008] The applicant of the present application has proposed, in Patent Document 5, a method for producing a granular organic fertilizer in which the slow-release degree is improved and the production cost is also improved.

[0009] Patent Document 6 discloses a powdered composition obtained by drying a mixture comprising an aqueous phase of a water-soluble polymer, a Pickering emulsion containing a non-encapsulating active substance, and a microcapsule slurry containing an encapsulating active substance.

[0010] Patent Document 7 discloses a liquid fertilizer in which the nitrogen content at the time of application is 5 to 15% w / w, and the ratio of methylene urea and / or polymethylene urea to the total nitrogen amount is 20 to 80%.

[0011] Patent Document 8 discloses a granular fertilizer comprising alginic acid and / or its salts having a viscosity of 25 mPa·s or more and 1000 mPa·s or less when prepared as a 1% by mass aqueous solution, a water-soluble fertilizer, and an inorganic powder.

[0012] Patent Document 9 discloses a method for forming a fertilizer composition having a sustained-release nitrogen compound by a melting process, which includes the step of mixing polyethylene wax with urea, formaldehyde, and one or more of an acid catalyst and an emulsifier to form a molten methylene urea mixture.

[0013] Examples of slow-release nitrogen fertilizers include chemically synthesized slow-release fertilizers such as CDU (acetaldehyde condensed urea), IB fertilizer (fertilizer containing isobutyraldehyde condensed urea (IBDU)), urea-formaldehyde, guanylurea, and oxamide.

[0014] These substances exert their fertilizing effect through hydrolysis and microbial decomposition, but it is difficult to adjust their fertilizing effect, and they have a fertilizing effect similar to that of organic fertilizers.

[0015] Ureaform is a chemically synthesized slow-release fertilizer produced by the condensation reaction of urea and formaldehyde. While it is attracting renewed attention as an uncoated slow-release fertilizer, the following points have been raised:

[0016] Ureaform is produced by mixing urea and formaldehyde, which undergo addition reactions under alkaline conditions and condensation reactions under acidic conditions. Condensation reactions also proceed during the subsequent drying process. Higher-order condensation reactions that occur during drying increase the amount of recalcitrant compounds. [Prior art documents] [Patent Documents]

[0017] [Patent Document 1] Japanese Patent Application Publication No. 8-165182 [Patent Document 2] Japanese Patent Publication No. 2001-26486 [Patent Document 3] Japanese Patent Publication No. 2001-58892 [Patent Document 4] Special Publication No. 2005-521761 [Patent Document 5] Japanese Patent Publication No. 2021-113135 [Patent Document 6] Special Publication No. 2021-506739 [Patent Document 7] Japanese Patent Publication No. 2022-102625 [Patent Document 8] Special Publication No. 2023-520608 [Patent Document 9] Japanese Patent Publication No. 2023-68545 [Overview of the project] [Problems that the invention aims to solve]

[0018] The present invention aims to propose a fertilizer made of ureaform, in which the fertilizer effect is regulated, the initial fertilizer effect is suppressed, and the fertilizer effect exhibits a near-linear type, as well as a method for producing the same. [Means for solving the problem]

[0019] Urea-form fertilizers have once again drawn attention as uncoated slow-release fertilizers. The inventor of the present application aimed to develop a fertilizer made of urea-form, with its fertilizer effect regulated, its initial fertilizer effect suppressed, and a fertilizer effect close to a linear type being exhibited, as well as a method for producing the same.

[0020] In urea-form fertilizers, generally, the higher the U / F ratio, which is the molar ratio of raw material urea to formaldehyde at the time of urea-form slurry, the lower the slow-release degree, and the lower the U / F ratio, the higher the slow-release property.

[0021] However, even when the U / F ratio is the same at the time of urea-form slurry, the fertilizer effectiveness varies depending on the reaction conditions and drying conditions, and the fertilizer effectiveness does not become constant only with the U / F ratio at the time of urea-form slurry.

[0022] Regarding urea-form fertilizers, it is conceivable to adjust the decomposition rate by adjusting the particle size or the fertilizer hardness. However, in either case, the adjustable range is not large, and it is difficult to control the fertilizer effect by these.

[0023] The inventor of the present application examined controlling the fertilizer effect of a fertilizer made of urea-form by adjusting the viscosity of the urea-form slurry.

[0024] In this case, it was recognized that when the viscosity increases, the condensation reaction progresses, the proportion of hardly soluble molecules increases, and the fertilizer effect cannot be obtained. On the other hand, when the viscosity decreases, the progress of the condensation reaction is small, and the fertilizer effect is immediately available due to the increase in the proportion of low molecular species, which is not desirable in terms of producing a slow-release fertilizer with a linear fertilizer effect.

[0025] Next, the inventor of the present application examined the combination of the viscosity of the urea slurry and the conditions of the drying process when producing the fertilizer by drying the urea slurry.

[0026] According to the examination by the inventor of the present application, it was found that urea slurry with controlled viscosity becomes fertilizers with different fertilizer effects when dried under the same conditions.

[0027] Furthermore, it was found that performing the drying process from the slurry in a short time is desirable in order to maintain the proportion of molecular species in the urea slurry and prevent the condensation reaction from progressing.

[0028] Furthermore, from the perspective of suppressing the progression of the condensation reaction due to heating, it was found that low-temperature drying, such as drying at 50°C or below, is desirable.

[0029] Through these studies, we found that by adjusting the viscosity of the ureas slurry and specifying the drying conditions, it is possible to produce fertilizers with more precise control over their fertilizer effect.

[0030] The present invention can be illustrated as follows: [1] to

[12] . [1] A fertilizer made by drying a urea slurry consisting of urea and formaldehyde in a drying process of 10 minutes or less, with a viscosity adjusted to the range of 0.01 to 0.60 (Pa·s, 23℃) and a molar ratio (U / F ratio) of urea to formaldehyde adjusted to the range of 0.5 to less than 1.0.

[0031] A urea slurry consisting of urea and formaldehyde, with a viscosity adjusted to the range of 0.01 to 0.60 (Pa·s, 23℃), and with a U / F ratio adjusted to the range of 0.5 to less than 1.0, can be dried in a drying process of 10 minutes or less. This short drying time suppresses the progression of synthesis reactions during drying, inhibits the formation of recalcitrant compounds, and allows for the production of a linear, slow-release fertilizer with suppressed initial fertilizer effects.

[0032] From this perspective, it is desirable that the viscosity of a ureas slurry with a U / F ratio adjusted to be in the range of 0.5 or more and less than 1.0 be in the range of 0.01 to 0.60 (Pa·s, 23°C), more preferably in the range of 0.03 to 0.25 (Pa·s, 23°C), and even more preferably in the range of 0.05 to 0.15 (Pa·s, 23°C).

[0033] The fertilizer described above is prepared by drying a liquid slurry, making it easy to mix with other fertilizers and highly versatile.

[0034] As described above, the U / F ratio, which is the molar ratio of urea to formaldehyde constituting the ureas slurry, can be in the range of 0.5 or more and less than 1.0.

[0035] By drying a ureas slurry with a U / F ratio within this range, adjusted to a viscosity of 0.01 to 0.60 (Pa·s, 23°C), more preferably adjusted to 0.03 to 0.25 (Pa·s, 23°C), and even more preferably adjusted to 0.05 to 0.15 (Pa·s, 23°C), in a drying process of 10 minutes or less, a linear, slow-release fertilizer with suppressed initial fertilizer effect can be obtained.

[0036] Furthermore, from this perspective, it is more desirable for the U / F ratio to be between 0.5 and 0.8.

[0037] According to the inventors' research, performing the drying process from the slurry in a short time is preferable in order to maintain the molecular species ratio in the ureas slurry and prevent the condensation reaction from progressing. From this viewpoint, it is desirable to obtain the above-mentioned fertilizer by drying a ureas slurry consisting of urea and formaldehyde, which has a viscosity in the range of 0.01 to 0.60 (Pa·s, 23°C), more preferably in the range of 0.03 to 0.25 (Pa·s, 23°C), and even more preferably in the range of 0.05 to 0.15 (Pa·s, 23°C), and a U / F ratio in the range of 0.5 to less than 1.0, more preferably in the range of 0.5 to 0.8, in a drying process of 10 minutes or less.

[0038] Furthermore, if dry fertilizer can be obtained, the drying process can be shortened to less than 10 minutes.

[0039] The fertilizer of the present invention described above is obtained by drying a urea slurry consisting of urea and formaldehyde in a drying process of 10 minutes or less, with the viscosity adjusted to a range of 0.01 to 0.60 (Pa·s, 23℃) and the molar ratio of urea to formaldehyde (U / F ratio) adjusted to a range of 0.5 or more and less than 1.0. As a result, it is an uncoated fertilizer, which does not generate microplastics and contributes to reducing environmental impact.

[0040] To meet the growing demand for slow-release fertilizers, coated fertilizers are becoming widely used. For example, coated urea with a plastic-based coating is now used very frequently.

[0041] However, it has been pointed out that the coating film and shells of coated fertilizers are washed into rivers and oceans, remaining as microplastics. This has recently come to be recognized as an environmental problem, and solving it has become an international effort.

[0042] As described above, the fertilizer of the present invention is uncoated, and is therefore capable of addressing such international issues.

[0043] [2] A fertilizer having a urea content of 2% by mass or less in the urea slurry [1].

[0044] [3] A fertilizer according to [1] or [2], wherein the urea content of the urea slurry is 1% by mass or less.

[0045] According to the inventors' studies, the above-mentioned fertilizer, which is obtained by drying a urea slurry consisting of urea and formaldehyde in a drying process of 10 minutes or less, is adjusted to have a viscosity in the range of 0.01 to 0.60 (Pa·s, 23℃), more preferably in the range of 0.03 to 0.25 (Pa·s, 23℃), and even more preferably in the range of 0.05 to 0.15 (Pa·s, 23℃), and has a U / F ratio in the range of 0.5 to less than 1.0, more preferably in the range of 0.5 to 0.8, and is dried in a drying process of 10 minutes or less, was found to be desirable in that the urea content in the urea slurry is within a predetermined ratio in order to suppress adhesion inside the drying equipment and deliquescence during the drying process, and to increase the recovery rate of the dried fertilizer by drying.

[0046] Furthermore, from this perspective, the urea content in the urea slurry consisting of urea and formaldehyde is preferably 2% by mass or less, and more preferably 1% by mass or less.

[0047] [4] A fertilizer comprising 0.1 to 10.0% by mass of an amino group-containing material in the urea slurry [1] to [3].

[0048] [5] A fertilizer comprising an amino acid or protein decomposition product, wherein the material containing an amino group exhibits a pH of 5.5 or higher when dissolved in water. [4]

[0049] According to the inventors' studies, in the above-mentioned fertilizer, which is obtained by drying a urea slurry consisting of urea and formaldehyde in a drying process of 10 minutes or less, with a viscosity adjusted to the range of 0.01 to 0.60 (Pa·s, 23℃), more preferably in the range of 0.03 to 0.25 (Pa·s, 23℃), and even more preferably in the range of 0.05 to 0.15 (Pa·s, 23℃), and a U / F ratio adjusted to the range of 0.5 or more and less than 1.0, more preferably in the range of 0.5 or more and 0.8 or less, it was desirable to blend a material containing amino groups into the urea slurry in order to obtain a high recovery rate.

[0050] In other words, it is desirable for the ureas slurry to contain a material with amino groups in order to increase the recovery rate of the dried product by drying.

[0051] From this viewpoint, it is desirable that the ureas slurry contains 0.1 to 10.0% by mass of an amino group-containing material, more preferably 1.0 to 5.0% by mass of an amino group-containing material, and even more preferably 2.0 to 5.0% by mass of an amino group-containing material.

[0052] Furthermore, according to the inventor's research, the material containing the amino group that exhibits the above-mentioned effects could be an amino acid or a protein hydrolysate that exhibits a pH of 5.5 or higher when dissolved in water.

[0053] [6] Fertilizers in which the drying is carried out by a spray dryer or a continuous spray fluid dryer [1] to [5].

[0054] In the above-mentioned fertilizer, a urea slurry consisting of urea and formaldehyde is dried in a drying step of 10 minutes or less, with a viscosity adjusted to the range of 0.01 to 0.60 (Pa·s, 23°C), more preferably to the range of 0.03 to 0.25 (Pa·s, 23°C), and even more preferably to the range of 0.05 to 0.15 (Pa·s, 23°C), and a U / F ratio adjusted to the range of 0.5 or more and less than 1.0, more preferably to the U / F ratio of 0.5 or more and 0.8 or less, the drying can be carried out by various methods. For example, it can be carried out by a spray dryer or a continuous spray fluid dryer.

[0055] The fertilizer obtained by drying with a spray dryer becomes a powder, making it easier to mix with other fertilizers and thus more versatile.

[0056] [7] A ureas slurry preparation step is performed to prepare a ureas slurry consisting of urea and formaldehyde, in which the viscosity is in the range of 0.01 to 0.60 (Pa·s, 23℃) and the U / F ratio, which is the molar ratio of urea to formaldehyde, is adjusted to be in the range of 0.5 or more and less than 1.0. A fertilizer manufacturing method comprising a drying step of drying the ureas slurry prepared in the ureas slurry preparation step in a drying step of 10 minutes or less.

[0057] By producing fertilizer using a fertilizer manufacturing method comprising a ureas slurry preparation step in which a ureas slurry consisting of urea and formaldehyde is adjusted to a viscosity in the range of 0.01 to 0.60 (Pa·s, 23℃) and a U / F ratio in the range of 0.5 or more and less than 1.0, and a drying step in which the ureas slurry prepared in the ureas slurry preparation step is dried in a drying step of 10 minutes or less, it is possible to obtain a linear, slow-release fertilizer with suppressed initial fertilizer effect by suppressing the progression of synthesis reactions during drying through short-time drying, thereby inhibiting the formation of recalcitrant compounds.

[0058] From this perspective, it is desirable that the viscosity of a ureas slurry with a U / F ratio adjusted to be in the range of 0.5 or more and less than 1.0 be in the range of 0.01 to 0.60 (Pa·s, 23°C), more preferably in the range of 0.03 to 0.25 (Pa·s, 23°C), and even more preferably in the range of 0.05 to 0.15 (Pa·s, 23°C).

[0059] According to the fertilizer manufacturing method described above, the manufactured fertilizer is prepared by drying a liquid slurry, making it easy to mix with other fertilizers and highly versatile.

[0060] As described above, the U / F ratio, which is the molar ratio of urea to formaldehyde constituting the ureas slurry, can be in the range of 0.5 or more and less than 1.0.

[0061] By drying a ureas slurry with a U / F ratio within this range, adjusted to a viscosity of 0.01 to 0.60 (Pa·s, 23°C), more preferably adjusted to 0.03 to 0.25 (Pa·s, 23°C), and even more preferably adjusted to 0.05 to 0.15 (Pa·s, 23°C), in a drying process of 10 minutes or less, a linear, slow-release fertilizer with suppressed initial fertilizer effect can be obtained.

[0062] Furthermore, from this perspective, it is more desirable for the U / F ratio to be between 0.5 and 0.8.

[0063] According to the inventors' research, performing the drying process from the slurry in a short time is preferable in order to maintain the molecular species ratio in the ureas slurry and prevent the condensation reaction from progressing. From this viewpoint, it is desirable to obtain the above-mentioned fertilizer by drying a ureas slurry consisting of urea and formaldehyde, which has a viscosity in the range of 0.01 to 0.60 (Pa·s, 23°C), preferably in the range of 0.03 to 0.25 (Pa·s, 23°C), and more preferably in the range of 0.05 to 0.15 (Pa·s, 23°C), and a U / F ratio in the range of 0.5 to less than 1.0, more preferably in the range of 0.5 to 0.8, in a drying process of 10 minutes or less.

[0064] Furthermore, if dry fertilizer can be obtained, the drying process can be shortened to less than 10 minutes.

[0065] The fertilizer of the present invention described above is obtained by drying a urea slurry consisting of urea and formaldehyde in a drying process of 10 minutes or less, with the viscosity adjusted to a range of 0.01 to 0.60 (Pa·s, 23℃) and the molar ratio of urea to formaldehyde (U / F ratio) adjusted to a range of 0.5 or more and less than 1.0. As a result, it is an uncoated fertilizer, which does not generate microplastics and contributes to reducing environmental impact.

[0066] To meet the growing demand for slow-release fertilizers, coated fertilizers are becoming widely used. For example, coated urea with a plastic-based coating is now used very frequently.

[0067] However, it has been pointed out that the coating film and shells of coated fertilizers are washed into rivers and oceans, remaining as microplastics. This has recently come to be recognized as an environmental problem, and solving it has become an international effort.

[0068] As described above, the fertilizer of the present invention is uncoated, and is therefore capable of addressing such international issues.

[0069] [8] A method for producing fertilizer, wherein the urea content of the ureas slurry is 2% by mass or less [7].

[0070] [9] A method for producing fertilizer according to [7] or [8], wherein the urea content of the ureas slurry is 1% by mass or less.

[0071] According to the inventors' studies, the above-mentioned fertilizer, which is obtained by drying a urea slurry consisting of urea and formaldehyde in a drying process of 10 minutes or less, is adjusted to have a viscosity in the range of 0.01 to 0.60 (Pa·s, 23℃), more preferably in the range of 0.03 to 0.25 (Pa·s, 23℃), and even more preferably in the range of 0.05 to 0.15 (Pa·s, 23℃), and has a U / F ratio in the range of 0.5 to less than 1.0, more preferably in the range of 0.5 to 0.8, and is dried in a drying process of 10 minutes or less, was found to be desirable in that the urea content in the urea slurry is within a predetermined ratio in order to suppress adhesion inside the drying equipment and deliquescence during the drying process, and to increase the recovery rate of the dried fertilizer by drying.

[0072] Furthermore, from this perspective, the urea content in the urea slurry consisting of urea and formaldehyde is preferably 2% by mass or less, and more preferably 1% by mass or less.

[0073]

[10] A fertilizer manufacturing method according to any of the following [7]-[9], wherein the ureas slurry is blended with 0.1 to 10.0% by mass of a material containing amino groups.

[0074]

[11] A method for producing a fertilizer in which the material containing an amino group exhibits a pH of 5.5 or higher when dissolved in water, and is an amino acid or a protein decomposition product

[10] .

[0075] According to the inventors' studies, in the above-mentioned fertilizer, which is obtained by drying a urea slurry consisting of urea and formaldehyde in a drying process of 10 minutes or less, with a viscosity adjusted to the range of 0.01 to 0.60 (Pa·s, 23℃), more preferably in the range of 0.03 to 0.25 (Pa·s, 23℃), and even more preferably in the range of 0.05 to 0.15 (Pa·s, 23℃), and a U / F ratio adjusted to the range of 0.5 or more and less than 1.0, more preferably in the range of 0.5 or more and 0.8 or less, it was desirable to blend a material containing amino groups into the urea slurry in order to obtain a high recovery rate.

[0076] In other words, it is desirable for the ureas slurry to contain a material with amino groups in order to increase the recovery rate of the dried product by drying.

[0077] From this viewpoint, it is desirable that the ureas slurry contains 0.1 to 10.0% by mass of an amino group-containing material, more preferably 1.0 to 5.0% by mass of an amino group-containing material, and even more preferably 2.0 to 5.0% by mass of an amino group-containing material.

[0078] Furthermore, according to the inventor's research, the material containing the amino group that exhibits the above-mentioned effects could be an amino acid or a protein hydrolysate that exhibits a pH of 5.5 or higher when dissolved in water.

[0079]

[12] A fertilizer manufacturing method in which the drying is carried out by a spray dryer or a continuous spray fluid dryer [7] to

[11] .

[0080] In the above-mentioned fertilizer, a urea slurry consisting of urea and formaldehyde is dried in a drying step of 10 minutes or less, with a viscosity adjusted to the range of 0.01 to 0.60 (Pa·s, 23°C), more preferably to the range of 0.03 to 0.25 (Pa·s, 23°C), and even more preferably to the range of 0.05 to 0.15 (Pa·s, 23°C), and a U / F ratio adjusted to the range of 0.5 or more and less than 1.0, more preferably to the U / F ratio of 0.5 or more and 0.8 or less, the drying can be carried out by various methods. For example, it can be carried out by a spray dryer or a continuous spray fluid dryer.

[0081] The fertilizer obtained by drying with a spray dryer becomes a powder, making it easier to mix with other fertilizers and thus more versatile.

[0082] As described above, the present invention proposes a fertilizer manufacturing method for producing fertilizer with more precise control over its fertilizing effect by adjusting the viscosity of the ureas slurry and specifying the drying conditions, and the fertilizer produced by this method.

[0083] Therefore, the present invention can also be described as a method for adjusting the fertilizer efficacy of a fertilizer manufactured by comprising a ureas slurry preparation step of preparing a ureas slurry consisting of urea and formaldehyde, in which the viscosity is in the range of 0.01 to 0.60 (Pa·s, 23℃) and the molar ratio of urea to formaldehyde, the U / F ratio, is adjusted to be in the range of 0.5 or more and less than 1.0, and a drying step of drying the ureas slurry prepared in the ureas slurry preparation step in a drying step of 10 minutes or less.

[0085] As will be further described in the embodiments described later, the present invention is not limited to the above description and the embodiments described later, and can be modified in various ways within the technical scope as understood from the claims. [Effects of the Invention]

[0086] According to this invention, it is possible to provide a fertilizer made of ureaform, in which the fertilizer effect is regulated, the initial fertilizer effect is suppressed, and the fertilizer effect exhibits a linear type, as well as a method for producing the same. [Brief explanation of the drawing]

[0087] [Figure 1] This graph shows the results of a test demonstrating that different fertilizers with varying degrees of slow release can be obtained by drying ureas slurry with controlled viscosity under identical conditions. [Figure 2] This graph shows the results of a test on the fertilizer effect when a material containing amino groups is added to a ureas slurry. [Modes for carrying out the invention]

[0088] <Examination Test 1: Examination of fertilizer efficacy when urea slurry with controlled viscosity is dried under the same conditions> Two types of urea slurries (AU-300, AU-X2303), consisting of urea and formaldehyde, with viscosity and the U / F ratio (molar ratio of urea to formaldehyde) adjusted as shown in Table 1, were dried under identical drying conditions using a spray dryer to prepare two types of fertilizer. The drying time for both was within 10 minutes.

[0089] The effectiveness of the two types of fertilizers prepared in this manner was investigated by observing the change in mineralization rate over time, as shown in Figure 1.

[0090] [Table 1] The results of the evaluation test are shown in Figure 1. Both fertilizers showed suppressed initial fertilizer effects and were found to have a fertilizer effect close to that of a linear type. Furthermore, the U / F ratio at the ureas slurry stage was 0.6 for both, and despite being dried under the same conditions, the results in Figure 1 confirmed that there were differences in fertilizer effects.

[0091] It was confirmed that fertilizers with different fertilizing effects (i.e., different slow-release properties) can be obtained by drying ureas slurry with controlled viscosity under the same conditions.

[0092] <Examination Test 2: Investigation of the effect of urea content in urea slurry on the drying process> We investigated the effect of the urea content in two urea slurries (AU-300 and AU-X2302), consisting of urea and formaldehyde, on the drying process.

[0093] The viscosity of the ureas slurry (AU-300) used in the study was 0.14 (Pa·s, 23°C), and the U / F ratio (molar ratio of urea to formaldehyde) was 0.6. The viscosity of the ureas slurry (AU-X2302) was 0.05 (Pa·s, 23°C), and the U / F ratio (molar ratio of urea to formaldehyde) was also 0.6.

[0094] Urea was added to the ureas slurries described above, as shown in Table 2, and after mixing, each was dried using a spray dryer under the same drying conditions. The drying time for all was within 10 minutes.

[0095] For comparison, AU-300 without urea was also dried under the same drying conditions, and the results are shown in Table 2.

[0096] [Table 2] As shown in Table 2, the control sample AU-300 had a total nitrogen (TN) of 15% in slurry form, and because no urea was added, the urea nitrogen (UN) / total nitrogen (TN) ratio was 0.00%, allowing for fertilizer preparation by drying with a spray dryer (SD). No adhesion occurred inside the spray dryer used for drying.

[0097] When 2% by mass of urea (0.16% urea nitrogen) was added to and mixed with the control sample AU-300, the slurry, which had a total nitrogen (TN) of 15.6% and a urea nitrogen (UN) / total nitrogen (TN) ratio of 1.03, was dried in a spray dryer (SD) to prepare fertilizer. No adhesion occurred inside the spray dryer used for drying.

[0098] When 4% by mass of urea (0.30% urea nitrogen) was added to and mixed with the control sample AU-300, the slurry, which had a total nitrogen (TN) of 16.1% and a urea nitrogen (UN) / total nitrogen (TN) ratio of 1.86, was also dried in a spray dryer (SD) to prepare fertilizer. No adhesion occurred inside the spray dryer used for drying.

[0099] When 8% by mass of urea (0.98% urea nitrogen) was added to and mixed with the control sample AU-300, the slurry, which had a total nitrogen (TN) of 17.3% and a urea nitrogen (UN) / total nitrogen (TN) ratio of 5.66, was dried in a spray dryer (SD) to prepare fertilizer. Although some residue was present inside the spray dryer used for drying, this did not hinder the preparation of fertilizer by drying with the spray dryer (SD).

[0100] When 0.08% urea was added to AU-X2302 as urea nitrogen, a slurry with a total nitrogen (TN) of 15.1% and a urea nitrogen (UN) / total nitrogen (TN) ratio of 0.53% was dried in a spray dryer (SD) to prepare fertilizer. No adhesion occurred inside the spray dryer used for drying.

[0101] When 2% by mass of urea (0.81% urea nitrogen) was added to AU-X2302 and mixed, the slurry, with a total nitrogen (TN) of 15.3% and a urea nitrogen (UN) / total nitrogen (TN) ratio of 5.28, was dried in a spray dryer (SD) to prepare fertilizer. No adhesion occurred inside the spray dryer used for drying.

[0102] When 4% by mass of urea (1.37% urea nitrogen) was added to AU-X2302 and mixed, the slurry, with a total nitrogen (TN) of 15.8% and a urea nitrogen (UN) / total nitrogen (TN) ratio of 8.68, was dried in a spray dryer (SD) to prepare fertilizer. Although some residue was present inside the spray dryer used for drying, this did not hinder the preparation of fertilizer by drying with the spray dryer (SD).

[0103] From the results of the study shown in Table 2, it was found that a urea content of 1.37% by mass or less in the urea slurry consisting of urea and formaldehyde is desirable from the viewpoint of preventing adhesion inside the drying equipment during the drying process, and from this viewpoint, a urea content of 0.98% by mass or less in the urea slurry consisting of urea and formaldehyde is even more desirable.

[0104] Further studies conducted by the inventors revealed that a urea content of 2% by mass or less in the urea slurry consisting of urea and formaldehyde is desirable in order to suppress adhesion inside the drying equipment and deliquescence during the drying process, and to increase the recovery rate of the dried fertilizer. Furthermore, from this perspective, it was found that a urea content of 1% by mass or less in the urea slurry consisting of urea and formaldehyde is even more desirable.

[0105] <Study on the fertilizer effect when materials containing amino groups are added to ureas slurry> The fertilizer effect of three urea slurry (AU-300, AU-X2302, AU-X2303) consisting of urea and formaldehyde was investigated when an amino group-containing material was added.

[0106] The viscosity of the ureas slurry (AU-300) used in the study was 0.14 (Pa·s, 23℃), and the U / F ratio, which is the molar ratio of urea to formaldehyde, was 0.6.

[0107] The viscosity of the ureas slurry (AU-X2302) was 0.05 (Pa·s, 23℃), and the U / F ratio, which is the molar ratio of urea to formaldehyde, was 0.6.

[0108] The viscosity of the ureas slurry (AU-X2303) was 0.24 (Pa·s, 23℃), and the U / F ratio, which is the molar ratio of urea to formaldehyde, was 0.6.

[0109] To each of these slurries, 10% by mass of glycine solution (G) was added, and the mixture was dried using a spray dryer (SD) to prepare the fertilizer. The drying time for all of them was within 10 minutes.

[0110] The effectiveness of each of the three fertilizers prepared in this manner was investigated by observing the change in mineralization rate over time, as shown in Figure 2.

[0111] All of the fertilizers were found to have suppressed initial fertilizer release, resulting in a fertilizer release that was close to linear.

Claims

1. A fertilizer obtained by drying a urea-formaldehyde slurry, which is prepared to have a viscosity in the range of 0.01 to 0.60 (Pa·s, 23°C) and a molar ratio of urea to formaldehyde (U / F ratio) in the range of 0.5 or more and less than 1.0, in a drying process of 10 minutes or less. A fertilizer comprising 0.1 to 10.0% by mass of glycine in the aforementioned urea-formaldehyde slurry.

2. The fertilizer according to claim 1, wherein the urea content in the urea-form slurry is 2% by mass or less.

3. The fertilizer according to claim 1 or claim 2, wherein the drying is performed by a spray dryer or a continuous spray fluid dryer.

4. A urea-formaldehyde slurry preparation step is performed to prepare a urea-formaldehyde slurry consisting of urea and formaldehyde, in which the viscosity is in the range of 0.01 to 0.60 (Pa·s, 23°C) and the U / F ratio, which is the molar ratio of urea to formaldehyde, is adjusted to be in the range of 0.5 or more and less than 1.

0. The process comprises a drying step of drying the urea-form slurry prepared in the urea-form slurry preparation step in a drying step of 10 minutes or less, A method for producing fertilizer, wherein the urea content in the urea-form slurry is 2% by mass or less.

5. The fertilizer manufacturing method according to claim 4, wherein glycine is added to the urea-form slurry in an amount of 0.1 to 10.0% by mass.

6. A ureaform slurry preparation step for preparing a ureaform slurry consisting of urea and formaldehyde, wherein the viscosity is in the range of 0.01 to 0.60 (Pa·s, 23°C) and the U / F ratio, which is the molar ratio of urea to formaldehyde, is adjusted to be in the range of 0.5 or more and less than 1.0; The process comprises a drying step of drying the urea-form slurry prepared in the urea-form slurry preparation step in a drying step of 10 minutes or less, The ureaform slurry contains 0.1 to 10.0% by mass of glycine. Fertilizer manufacturing method.

7. The fertilizer manufacturing method according to claim 6, wherein the urea content in the urea-form slurry is 2% by mass or less.

8. The fertilizer manufacturing method according to any one of claims 4 to 7, wherein the drying is performed by a spray dryer or a continuous spray fluid dryer.

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