JPH062630B2 - Granular fertilizer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a granular fertilizer containing a slow-release nitrogen fertilizer component.

BACKGROUND OF THE INVENTION Ammonium sulfate, urea, ammonium salt, ammonium nitrate, etc., which have been conventionally used as nitrogen fertilizers, are all easily dissolved in water and often flow out in soil before they are absorbed by plants. Particularly, when the above nitrogen fertilizer is used under the flooded condition such as a paddy field, it is difficult to effectively prevent the loss of the fertilizer flowing out.

Therefore, there is already known a technique of using a nitrogen-containing poorly soluble organic substance as a nitrogen fertilizer, and such a nitrogen fertilizer is called a slow-release nitrogen fertilizer. Slow-acting nitrogen fertilizers include oxamide, ureaform, isobutylidene diurea, guanylurea, diflufurylidene triurea,
Urea-Z, glycoluril, crotonylidene diurea and the like are known. Among such slow-release nitrogen fertilizers, oxamide [(CONH ₂ ) ₂ ] is excellent as a slow-release nitrogen fertilizer because it has low solubility in water and has no chemical damage to crops. It has been put to practical use. Slow-release nitrogen fertilizers such as oxamide are usually obtained as powders.

However, the slow-release nitrogen fertilizer in the form of powder is decomposed relatively early by the degrading bacteria in the soil and mineralized (meaning that the slow-release nitrogen fertilizer is decomposed to a form that can be absorbed by plants), The mineralized component is likely to be lost due to runoff as in the case of the above-mentioned ordinary nitrogen fertilizer, so that the feature of the slow-acting nitrogen fertilizer, which is slow-acting, may not be fully utilized.

Therefore, by controlling the elution of the slow-release nitrogen fertilizer and suppressing the contact between the slow-release nitrogen fertilizer and the degrading bacteria, the mineralization rate of the slow-release nitrogen fertilizer is reduced and the fertilizer of the slow-release nitrogen fertilizer is reduced. Technology is used to maintain the effect for a long time. As such a method, there is a method of controlling the mineralization rate by molding a fertilizer containing a slow-release nitrogen fertilizer into particles.

For example, Japanese Examined Patent Publication (Kokoku) No. 47-6375 discloses a method for controlling the decomposition of oxamide, which is mainly characterized by mixing and granulating oxamide and gypsum. That is, this method is a method of controlling the decomposition of oxamide by granulating with gypsum to block the contact between the oxamide and the oxamide-decomposing bacterium under field conditions. Further, this publication discloses, as a specific example, a granular fertilizer obtained by granulating a composition composed of a 1: 2 mixture of oxamide, gypsum and lime superphosphate and dissolved phosphorus fertilizer.

Generally, when a fertilizer composition containing gypsum and a phosphate fertilizer component is granulated, the gypsum and the phosphate fertilizer component react with each other to form a water-insoluble salt such as dicalcium phosphate (CaHPO ₄ .2H ₂ O). It is known that the use of gypsum and a phosphate fertilizer component as described above improves the shape retention (underwater shape stability) under flooded conditions. That is, as described above, 1: 2 of lime superphosphate and dissolved phosphorus fertilizer
It is conceivable that the insoluble salt such as dilime phosphate produced under the flooded condition may act to improve the shape stability in water by using the mixture of the above and gypsum.

However, when a granular fertilizer is actually produced by producing insoluble salts such as dicalcium phosphate, the obtained granular fertilizer does not necessarily show various characteristics such as shape stability in water under flooded conditions or particle hardness. May not improve to the level expected by. It is speculated that this may be because the type and amount of the insoluble salt produced, or the state of existence of the insoluble salt in the granular fertilizer varies depending on the conditions during production.

Therefore, the present inventor has examined conditions for producing an insoluble salt such as dicalcium phosphate. As a result, the reaction for producing an insoluble salt such as dicalcium phosphate to be produced coexists with the type and amount of the phosphoric acid component used. Since it is observed that it is significantly affected by the type and amount of other ingredients,
It was found that by adjusting these, it is possible to obtain a granular fertilizer containing oxamide, which has a hardness higher than that of the above-mentioned granular fertilizer and has good underwater shape stability.

By using an insoluble salt such as dicalcium phosphate, not only oxamide but also other slow-release nitrogen fertilizers can be effectively released.

[Object of the Invention] An object of the present invention is to provide a granular slow-release fertilizer containing a slow-release nitrogen fertilizer having sufficient hardness and good shape stability in water.

SUMMARY OF THE INVENTION The present invention relates to a slow-release nitrogen fertilizer component and 30 to 90 parts by weight of ammonium chloride, 2 to 100 parts by weight of the fertilizer component.
0-90 parts by weight diammonium phosphate and 30-90
A part of gypsum, and the compounding amount of the diammonium phosphate is in the range of 0.7 to 1.8 mol relative to 1 mol of the gypsum, which is a granulated product. It is in granular fertilizer.

[Effects of the Invention] Since the granular fertilizer of the present invention has high hardness of each particle and is less likely to disintegrate in water, the elution rate of the slow-release nitrogen fertilizer component can be effectively suppressed.

In particular, the granular fertilizer of the present invention has a high hardness of each particle even when using an oxamide whose formability is inferior to other slow-release nitrogen fertilizers, and the granular fertilizer is less likely to disintegrate in water. Therefore, the elution rate of oxamide can be effectively suppressed.

DETAILED DESCRIPTION OF THE INVENTION The present invention basically granulates a composition containing a slow-release nitrogenous fertilizer component such as oxamide and a specified amount of gypsum, diammonium phosphate and ammonium chloride to this component. This is a granular fertilizer obtained. Therefore, when obtaining the granular fertilizer of the present invention, first, a composition containing a specific amount of gypsum, diammonium phosphate and ammonium chloride is prepared. The composition comprises a slow-release nitrogen fertilizer (component). In the present invention, the usual slow-release nitrogen fertilizer can be used.

Examples of slow-release nitrogen fertilizers include sparingly soluble synthetic nitrogen compounds and sparingly soluble amide compounds, condensates of aldehydes and urea, or guanidine-based compounds, triazine-based compounds, and urea-type condensates. it can. More specifically, oxamide (OX) is an example of a sparingly soluble amide compound, and ureaform (UF), isobutylidene diurea (IB) is an example of a condensation product of an aldehyde and urea.
Crotonylidene diurea (CDU), urea-Z, glycoluril and diflufurylidene triurea (2F3U)
As an example of a guanidine-based compound, guanylurea (G
Mention may be made of the phosphates and sulfates of U). Moreover, cyanuric acid can be mentioned as an example of a triazine-based compound, and triuret can be mentioned as an example of its urea condensate. The slow-release nitrogenous fertilizer may be used alone or in combination of two or more kinds. In particular, the particle fertilizer of the present invention has good properties even when any of the slow-effect nitrogen fertilizers of the above-mentioned slow-effect nitrogen fertilizers is used, but in particular among the slow-effect nitrogen fertilizers, the formability is excellent. The granular fertilizer of the present invention is suitable as a slow-effect nitrogen fertilizer because it can be a granular fertilizer having good properties even when it contains an inferior oxamide as a main component. .

The content rate of the slow-releasing nitrogen fertilizer is usually 50% by weight or less. Further, it is preferable that the content is in the range of 5 to 40% by weight. If the content of the slow-release nitrogen fertilizer is higher than 50% by weight, the blending ratio of gypsum, diammonium phosphate, ammonium chloride, etc. will be low, so the strength of the obtained particles may be low, and therefore, The rate of mineralization of slow-acting nitrogen fertilizers may not be effectively controlled.

In the following description, oxamide will be mainly described as the slow-acting nitrogen fertilizer, but it goes without saying that in such a case, the slow-acting nitrogen fertilizer other than oxamide has the same effect.

The composition of the granular fertilizer of the present invention is ammonium chloride (ammonium chloride).
including. As ammonium chloride, usual one can be used.

Urea, ammonium sulfate (ammonium sulfate), ammonium nitrate (ammonium nitrate), ammonium chloride (ammonium salt), and the like are known as ordinary nitrogen fertilizers, and among these, ammonium sulfate is often used. The present inventor selects ammonium chloride among the above nitrogen fertilizers in the process of forming an insoluble salt using oxamide, gypsum and diammonium phosphate, whereby ammonium chloride acts as a normal fertilizer. Not only that, it has been found to have the effect of significantly increasing the hardness of the resulting granular fertilizer. That is, for example, when ammonium sulfate is used, the reaction between gypsum and ammonium sulfate simultaneously progresses during the reaction between gypsum and diammonium phosphate, so that ammonium syngenite [(NH ₄ ) ₂ Ca (SO ₄ ) ₂ · H ₂
O] is excessively produced. Therefore, dicalcium phosphate (CaH) is highly useful as a component that imparts hardness to granular fertilizer.
Since the production of cured products such as PO ₄ .2H ₂ O) is suppressed, the hardness of the obtained granular fertilizer is not sufficiently improved. Therefore, when a specific amount of ammonium chloride is used instead of ammonium sulfate, the amount of ammonium syngenite produced is controlled within an appropriate range, and it is the main component for imparting hardness and shape stability in water to granular fertilizer. Good formation of insoluble salts such as dicalcium phosphate.

Therefore, in the present invention, the compounding amount of ammonium chloride is 30 to 90 parts by weight with respect to 100 parts by weight of the above oxamide.
It is set within the range of parts by weight (preferably 35 to 80 parts by weight). If the amount of ammonium chloride is small, insoluble salts such as dicalcium phosphate are not formed well, so the hardness of fertilizer particles cannot be sufficiently improved, and if the amount is too large, the amounts of other components inevitably increase. Since the amount of the fertilizer decreases, the granular fertilizer having sufficient hardness and stability in water cannot be obtained.

Further, in the composition, the blending amount of ammonium chloride and the below-described diammonium phosphate is 35:65 by weight.
It is preferably within the range of to 65:35. By adjusting the amount of ammonium chloride to be within the above range, ammonium chloride acts more effectively when forming an insoluble salt such as dilime phosphate, and also acts effectively as a fast-acting nitrogen fertilizer component.

The composition comprises gypsum. As the gypsum, usual ones such as hemihydrate gypsum and dihydrate gypsum can be used. The blending amount of gypsum is 30 to 90 relative to 100 parts by weight of the above oxamide.
It is set within the range of parts by weight (preferably 50 to 80 parts by weight).

Further, the composition comprises diammonium phosphate. The compounding amount of diammonium phosphate [(NH ₄ ) ₂ HPO ₄ ] is set within the range of 20 to 90 parts by weight (preferably 30 to 80 parts by weight) with respect to 100 parts by weight of oxamide. In addition,
Diammonium phosphate, which is usually used as a fertilizer, is rarely a pure substance of diammonium phosphate represented by the above formula, and is usually monoammonium phosphate [(NH ₄ ) H ₂
PO ₄ ]. In the present invention, the diammonium phosphate may contain impurities such as monoammonium phosphate which are contained in diammonium phosphate as a normal fertilizer. In this case, the amount of diammonium phosphate blended is the amount of diammonium phosphate in the mixture.

However, the reactivity with gypsum is better with diammonium phosphate, and the insoluble salt such as dilime phosphate present in the granular fertilizer of the present invention can be separated from gypsum with mainly this diammonium phosphate. As a reaction product, monoammonium phosphate hardly reacts.

In the present invention, monoammonium phosphate can be positively blended. When monoammonium phosphate is blended, the blending amount is usually set in the range of 20 to 90 parts by weight (preferably 30 to 80 parts by weight) with respect to 100 parts by weight of oxamide. The monoammonium phosphate thus blended effectively acts as a phosphate fertilizer component and a nitrogen fertilizer component.

The granular fertilizer of the present invention is a granulated product of a composition containing the above components. That is, the above-mentioned components are mixed, an appropriate amount (usually 10 to 20 parts by weight of water relative to 100 parts by weight of the mixture) is added thereto, and a conventional method (for example, a plate type granulator, an extrusion granulator) is added. Granulation method using
Obtained by drying.

It is speculated that the granulated gypsum and the diammonium phosphate thus reacted react with each other by granulation and drying to form an insoluble salt such as dilime phosphate.

FIG. 1 shows an example of the effect of the compounding molar ratio of diammonium phosphate to the compounding amount of gypsum on the hardness of the granular fertilizer of the present invention.

That is, FIG. 1 shows that the amount of nitrogen contained in the oxamide in the granular fertilizer is about 50% by weight with respect to the total amount of nitrogen in the granular fertilizer.
(OX-50) to maintain such that, and nitrogen contained in the fertilizer, the ratio of phosphoric acid and potassium (N-P ₂ O ₅ -K
₂ O) is maintained at 14-14-14, and the hardness of the granular fertilizer produced by using the composition prepared by changing the compounding amounts of gypsum and diammonium phosphate, and the gypsum and diammonium phosphate in the composition. It is a graph which shows the example of the relationship with and the molar ratio. Note that potassium chloride was used as the potassium fertilizer component.

As is clear from FIG. 1, the hardness of granular fertilizers having a molar ratio of diammonium phosphate to gypsum of 0.4 or 0.6 is as low as 1.3 kg and 1.0 kg, respectively. The hardness of granular fertilizer around 0.7 is about 3.0
Increases rapidly with kg. The hardness of the granular fertilizer having a molar ratio of 1.4 shows a maximum value of 9.4 kg. However, when the molar ratio is further increased, the hardness is decreased.

Therefore, in the composition used for granulation, the amount of diammonium phosphate blended with 1 mol of gypsum is 0.7-1.
Set within the range of 8 mol. Further, by setting the compounding amount of diammonium phosphate within the range of 0.8 to 1.8 mol, the hardness of the granular fertilizer becomes about 5 kg, which is preferable.
Further, the underwater shape stability is also improved.

In the granular fertilizer obtained by granulating the composition thus prepared, as a component that imparts hardness and shape stability in water to the granular fertilizer, in addition to dicalcium phosphate described above, unreacted gypsum, A proper amount of ammonium singenite (NH ₄ ) ₂ Ca
(HPO ₄ ) ₂ etc. are presumed to exist. Among them, dicalcium phosphate and an appropriate amount of ammonium singenite act directly as a substance that imparts hardness to fertilizer particles, and (NH ₄ ) ₂ Ca (HPO ₄ ) ₂ decomposes in flooded conditions. As a result, dicalcium phosphate is produced, and it is presumed that it acts as a substance that subsequently gives hardness to fertilizer particles. It is presumed that these substances and unreacted gypsum are interrelated with each other to form the granular fertilizer of the present invention having high hardness and good shape stability in water.

In addition, the unreacted gypsum has the function of blocking the infiltration of degrading bacteria into the granular fertilizer. Therefore, the mineralization rate of the slow-release nitrogenous fertilizer can be controlled even under field conditions.

The granular fertilizer of the present invention is a granulated product of a composition containing a specific amount of a slow-release nitrogen fertilizer, gypsum, diammonium phosphate and ammonium chloride as main components. The granular fertilizer can also be a composite granular fertilizer containing other fertilizer components.

That is, the granular fertilizer of the present invention includes, in addition to the above components, nitrogen fertilizers other than slow-release nitrogen fertilizers (eg, ammonium nitrate, lime nitrogen, urea), phosphate fertilizers (eg, lime superphosphate, iodine phosphate fertilizer), Potassium fertilizer (eg, potassium chloride), organic fertilizer (eg, oil cake, fish meal), trace element (eg, Mn, Fe, B, Cu, Zn, C)
It may be a compound granular fertilizer including a fertilizer containing 1).

When the above fertilizer components are blended, the total content of the above fertilizer components is usually 80% by weight or less (preferably 60% by weight).
% Or less).

When using a compound granular fertilizer, potassium chloride is preferably used as potassium fertilizer, and when using potassium chloride, 50 to 10 parts by weight per 100 parts by weight of a slow-release nitrogen fertilizer is used.
It is preferable to use the compounding amount within the range of 0 part by weight.

The granular fertilizer of the present invention may be mixed with a synthetic resin such as polyvinyl alcohol for the purpose of increasing the hardness of each particle to improve the shape stability in water.

There is no particular limitation on the shape and size of the granular fertilizer of the present invention, but it is usually granular or granular having a particle diameter within the range of 1 to 10 mm. Especially the particle size is 1.5 ~
Granular or granular particles within the range of 5.5 mm are
It is preferable because it has good workability such as scattering during fertilization.

In the granular fertilizer of the present invention, the hardness of each particle is high, and the particles (particle diameter 3.5 to 4.
The average hardness of 5 mm is usually 3 kg or more (preferably 5 kg or more.) Further, the shape stability in water is excellent such that the fertilizer particles are less likely to collapse in a short time when placed in water. , The rate of mineralization of slow-release nitrogen fertilizer in flooded soil is reduced.

The pH value of water when 1 g of the granular fertilizer of the present invention is added to 100 ml of water at 25 ° C is usually in the range of 4 to 7.

When the granular fertilizer of the present invention is used, short-term leaching and runoff of the slow-release nitrogen fertilizer in water, which has been the biggest drawback of conventional fertilizers, is eliminated, and extremely long-term fertilization effect is exhibited. In that respect, it is very useful in practice.

Next, examples and comparative examples of the present invention will be shown.

[Example 1] 22.0 parts by weight of oxamide powder, 15.0 parts by weight of gypsum,
A composition was obtained by thoroughly mixing 9.2 parts by weight of diammonium phosphate, 15.0 parts by weight of monoammonium phosphate, 13.1 parts by weight of ammonium chloride and 23.3 parts by weight of potassium chloride in a mixer. The compounding amount of diammonium phosphate with respect to 1 mol of gypsum in the above composition was 0.85 mol.

Then, 12 parts by weight of water is added to 100 parts by weight of this composition, and the resulting granulated product is granulated using a plate-type granulator, and the resulting granulated product is dried by heating to a diameter within a range of 2 to 5 mm. A granular fertilizer having

Example 2 In Example 1, the compounding amount of diammonium phosphate was 1
Granular fertilizer having a diameter within the range of 2 to 5 mm except that 6.1 parts by weight, the amount of monoammonium phosphate compounded was 9.0 parts by weight, and the amount of ammonium chloride compounded was 10.2 parts by weight. Got The compounding amount of diammonium phosphate with respect to 1 mol of gypsum in the composition was 1.48 mol.

Comparative Example 1 In Example 1, 15.5 parts by weight of ammonium sulfate was used instead of 13.1 parts by weight of ammonium chloride, the amount of oxamide was 22.2 parts by weight, and the amount of diammonium phosphate was 14.3 parts by weight. A granular fertilizer having a diameter in the range of 2 to 5 mm was obtained in the same manner except that 7 parts by weight and the content of potassium chloride were 22.2 parts by weight. The compounding amount of diammonium phosphate with respect to 1 mol of gypsum in the composition was 0.85 mol.

[Evaluation Items] Each of the granular fertilizers obtained in Examples 1 and 2 and Comparative Example 1 was tested for hardness, pH value, and shape stability in water to obtain a slow-release nitrogen fertilizer-containing granular fertilizer. The characteristics were evaluated. These test methods are as follows. In the test described below, among the obtained granular fertilizers, those having a particle size within the range of 3.5 to 4.5 mm (4.5 mm for the underwater shape stability test) were used. It was selected and used.

Hardness: The average value of 10 oxamide-containing granular fertilizer particles measured using a Kiya type hardness meter is shown.

pH value: 1 g of oxamide-containing granular fertilizer, 100 ml of water (25 ° C)
PH of this aqueous suspension.
The value was measured.

Underwater shape stability: Oxamide-containing granular fertilizer particles having a diameter of 4.5 mm were immersed in water, and the state of the particles after 10 hours was observed.

The evaluation results are shown in Table 1.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship of the compounding amount (molar ratio) of gypsum and diammonium phosphate on the hardness of the granular fertilizer of the present invention.

Claims (4)

[Claims] 1. A slow-release nitrogen fertilizer component and the fertilizer component 100.
30 to 90 parts by weight of ammonium chloride, based on parts by weight,
20-90 parts by weight of diammonium phosphate and 30-9
A granulated product of a composition containing 0 part by weight of gypsum and having a compounding amount of the diammonium phosphate within a range of 0.7 to 1.8 mol per 1 mol of the gypsum. Granular fertilizer to do. 2. The composition according to claim 1, wherein the content of diammonium phosphate in the composition is in the range of 0.8 to 1.8 mol per 1 mol of gypsum. Granular fertilizer. 3. The weight ratio of ammonium chloride to diammonium phosphate in the composition is 35:65 to 65:35.
The granular fertilizer according to claim 1, wherein the granular fertilizer is in the range. 4. The granular fertilizer according to claim 1, wherein the slow-release nitrogen fertilizer component is oxamide.