Method for preparing nitrogen-phosphorus binary fertilizer using humic acid as disintegrator and nitrogen-phosphorus binary fertilizer

Abstract

The present invention proposes a preparation method for preparing nitrogen-phosphorus binary fertilizer by using humic acid as a disintegrator, and the specific method includes: mixing neutralized slag, slag acid and humic acid; and neutralizing the mixed product with ammonia to obtain slurry; and granulating and drying the slurry to obtain the nitrogen-phosphorus binary fertilizer. The nitrogen-phosphorus binary fertilizer not only has a faster disintegration speed, but also is rich in nitrogen and phosphorus elements required for crop growth, and further has the functions of promoting crop growth, increasing yield and improving quality.

Description

Technical Field

[0001] The present invention relates to the technical field of agriculture, and in particular to a method for preparing nitrogen-phosphorus binary fertilizer by using humic acid as a disintegrator and the nitrogen-phosphorus binary fertilizer. Background Art

[0002] Fertilizers play an important role in agricultural production. In the phosphate fertilizer and phosphorus chemical industry, when producing high-concentration phosphoric acid, potassium dihydrogen phosphate, industrial monoammonium phosphate and other products, some concentrated slag acid and neutralization slag will be produced as by-products. Among them, the neutralization slag acid index is (dry basis, effective P2O5 content is about 25-32%). Using neutralization slag to produce nitrogen-phosphorus binary fertilizer can digest neutralization slag and slag acid, and the binary fertilizer produced can be used as a raw material for blended fertilizer (BB fertilizer) or directly used as low-nutrient diammonium.

[0003] Fertilizer granules such as diammonium phosphate disintegrate relatively slowly. It takes more than 1 hour for diammonium phosphate granules to disintegrate in water. For low-nutrient nitrogen-phosphorus binary fertilizers, increasing the disintegration speed will be very beneficial to the effect of the fertilizer.

[0004] At present, in order to accelerate the disintegration of fertilizers, disintegrants are mainly added in production. Different disintegrants are used in nitrogen-phosphorus binary fertilizers and ammonium phosphate. Adding hydroxypropyl cellulose and bentonite as disintegrants to ammonium phosphate has no effect on improving the effect of fertilizers, but only accelerates the disintegration of particles, and the disintegration speed is relatively slow, about 30 minutes or more. How to increase the disintegration speed of nitrogen-phosphorus binary fertilizers and improve the effect of fertilizers is a technical problem that needs to be solved urgently in the industry. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art to a certain extent. In order to solve the problem of slow disintegration of nitrogen-phosphorus binary fertilizer to a certain extent, the inventor has proposed a method for preparing a fast-disintegrating nitrogen-phosphorus binary fertilizer after continuous attempts and innovations. The inventor has found that the neutralized slag and slag acid produced in phosphorus chemical production can be used as fertilizers for nitrogen-phosphorus binary fertilizer, and the prepared nitrogen-phosphorus binary fertilizer contains a large amount of phosphorus and nitrogen. Moreover, by using humic acid as a disintegrating agent, not only the disintegration speed of the nitrogen-phosphorus binary fertilizer is accelerated, but also the fertilizer efficiency is improved.

[0006] To this end, in one aspect of the present invention, the present invention proposes a method for preparing nitrogen-phosphorus binary fertilizer using humic acid as a disintegrant. According to an embodiment of the present invention, the method comprises mixing neutralized slag, slag acid and humic acid; and neutralizing the mixed product with ammonia to obtain a slurry; and granulating and drying the slurry to obtain the nitrogen-phosphorus binary fertilizer. The above method according to the embodiment of the present invention is simple to operate, and the prepared nitrogen-phosphorus binary fertilizer disintegrates quickly and has good fertilizer effect.

[0007] It should be noted that the neutralized slag and slag acid are part of the by-products when producing high-concentration phosphoric acid, potassium dihydrogen phosphate, industrial monoammonium phosphate and other products in the phosphate fertilizer and phosphorus chemical industries. According to a specific embodiment of the present invention, preferably, the neutralized slag is a by-product of refined phosphates from the phosphorus chemical industry, wherein the indicators of the neutralized slag are nitrogen content not less than 5%, effective phosphorus not less than 25% (dry basis), water-soluble phosphorus not less than 12.5% ​​(dry basis), and moisture content of 15-35%.

[0008] According to an embodiment of the present invention, the method for preparing nitrogen-phosphorus binary fertilizer may further include at least one of the following additional technical features:

[0009] According to an embodiment of the present invention, the mass ratio of the neutralized slag (dry basis) to the slag acid (dry basis) is (550-800): (150-400). The inventors have found through a large number of experiments that the use of the above raw material ratio not only accelerates the disintegration speed of the nitrogen-phosphorus binary fertilizer, but also contains phosphorus and nitrogen elements required for crop growth, and has the functions of promoting crop growth, increasing yield, and improving quality.

[0010] According to an embodiment of the present invention, the mass content of humic acid in the mixed treatment product is 1.0-1.5%. The inventors have found through a large number of experiments that adding 1.0-1.5% humic acid can accelerate the disintegration rate of nitrogen and phosphorus binary fertilizer in water.

[0011] According to an embodiment of the present invention, the second mixing treatment is performed at a pH of 5.0 to 6.0.

[0012] According to an embodiment of the present invention, the humic acid is one or more of plant-derived humic acid and mineral-derived humic acid, and optionally, the molecular weight of the humic acid is 100,000-1,000,000. When the molecular weight of the humic acid is within this range, the disintegration speed of the prepared nitrogen-phosphorus binary fertilizer can be increased.

[0013] According to an embodiment of the present invention, the granulation and drying process is carried out in a granulator, the head temperature of the granulator is 400-500° C., and the tail temperature is 60-100° C. The inventors have found through a large number of experiments that the temperature within the range can fully remove the moisture in the slurry, so that the obtained nitrogen-phosphorus binary fertilizer has consistent quality, relatively uniform moisture content distribution, and improves the yield rate.

[0014] According to an embodiment of the present invention, the granulation is performed by spray granulation or coating granulation. The inventors found that the granules prepared by the granulation method have a smooth, hard and uniform surface.

[0015] According to an embodiment of the present invention, the moisture content of the nitrogen-phosphorus binary fertilizer granules after the granulation and drying process is less than 2.5%, preferably, less than 2%.

[0016] According to an embodiment of the present invention, the granulation and drying process further comprises sequentially cooling, screening, and anti-caking treatment of the granulation and drying product to obtain nitrogen-phosphorus binary fertilizer granules.

[0017] According to an embodiment of the present invention, the temperature of the granulation and drying product after the cooling is 30-50°C, preferably 30-40°C.

[0018] According to an embodiment of the present invention, the particle size of the granulation and drying product after the screening is 1 to 4.0 mm.

[0019] In another aspect of the present invention, the present invention proposes a nitrogen-phosphorus binary fertilizer. According to an embodiment of the present invention, the nitrogen-phosphorus binary fertilizer is prepared by the method described above. According to a specific embodiment of the present invention, the nitrogen-phosphorus binary fertilizer prepared by the method described above not only has a high nitrogen content, an effective phosphorus content and a water-soluble phosphorus content, which meets the needs of plant growth, but also can be quickly disintegrated in water, thereby improving the use efficiency of the nitrogen-phosphorus binary fertilizer.

[0020] According to an embodiment of the present invention, the above-mentioned nitrogen-phosphorus binary fertilizer may further include at least one of the following additional technical features:

[0021] According to an embodiment of the present invention, the disintegration time of the nitrogen-phosphorus binary fertilizer in water is no more than 30 minutes.

[0022] According to an embodiment of the present invention, the disintegration time of the nitrogen-phosphorus binary fertilizer in water is 10 to 30 minutes. The disintegration speed of the nitrogen-phosphorus binary fertilizer according to an embodiment of the present invention is significantly improved.

[0023] According to an embodiment of the present invention, the nitrogen-phosphorus binary fertilizer (40-45% total nutrients) has a total nitrogen content of not less than 6.0%, an available phosphorus content of not less than 30.0%, and a water-soluble phosphorus content of not less than 18.0%. According to a specific embodiment of the present invention, the nitrogen-phosphorus binary fertilizer is rich in nitrogen and phosphorus elements required for crop growth, further meeting the needs of plant growth.

[0024] In yet another aspect of the present invention, the present invention provides a blended fertilizer. According to an embodiment of the present invention, the blended fertilizer includes the aforementioned nitrogen-phosphorus dual fertilizer.

[0025] It should be noted that all the characteristics and advantages described above for the aforementioned nitrogen-phosphorus binary fertilizer are also applicable to this blended fertilizer and will not be described in detail here.

[0026] Technical effects of the present invention:

[0027] The present invention uses humic acid as a disintegrant for the first time, and is used for the disintegration of nitrogen-phosphorus binary fertilizer in the fertilizer field. The present invention adds humic acid as a disintegrant in the preparation of nitrogen-phosphorus binary fertilizer, which effectively accelerates the disintegration rate of nitrogen-phosphorus binary fertilizer, and can achieve a disintegration rate of 10-30 minutes. In addition to accelerating the disintegration, humic acid can reduce the fixation of water-soluble phosphorus, and its effect can be expressed by measuring the value of the water-soluble phosphorus fixation difference rate content. The larger the value of the water-soluble phosphorus fixation difference rate, the greater the fixation effect on the reduced water-soluble phosphorus.

[0028] In addition, humic acid is a key component of soil organic matter. This application adds humic acid to: 1. Effectively improve fertilizer efficiency, improve the utilization rate of nitrogen, phosphorus, potassium, and trace elements, and improve photosynthetic efficiency; 2. Improve the soil, promote soil aggregate structure, regulate soil microecology, and regulate and buffer soil pH; 3. Enhance stress resistance: drought resistance, cold resistance, saline-alkali resistance, and disease resistance; 4. Improve quality: reduce heavy metal content, reduce pesticide residues, and improve crop quality; 5. Stimulate crop growth: early germination, early flowering, early maturity, increase grain weight, fruit weight, and increase yield.

[0029] The principle of humic acid accelerating disintegration: Humic acid, as an organic filler, can play a loosening role in the particles. When the particles dissolve, due to its fast dissolution rate, humic acid will dissolve first, and tiny channels will appear in the particles. Humic acid comes out from the channels. Due to the dissolution of the humic acid filler, the particles break, which accelerates the disintegration of the particles.

[0030] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0032] Figure 1 is a diagram of nitrogen-phosphorus binary fertilizer particles according to an embodiment of the present invention;

[0033] Figure 2 is a disintegration diagram of nitrogen and phosphorus binary fertilizer after water dissolution according to an embodiment of the present invention;

[0034] Figure 3 This is a disintegration diagram of nitrogen and phosphorus binary fertilizer after being dissolved in water according to an embodiment of the present invention, wherein the humic acid content in Figure A is 0.5%, and the humic acid content in Figure B is 1%. DETAILED DESCRIPTION

[0035] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. If no specific techniques or conditions are specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0036] In the following examples, the chemical reaction equation involved in the neutralization reaction is:

[0037] NH3+H3PO4=NH4H2PO4

[0038] 2NH3+H3PO4=(NH4)2HPO4,

[0039] Among them, H3PO4 is contained in the neutralized slag and slag acid, the pH of monoammonium phosphate (NH4H2PO4) is about 4.3, and the pH of diammonium phosphate ((NH4)2HPO4) is about 8. The nitrogen-phosphorus dibasic fertilizer obtained by controlling the pH to 5.0-6.0 is a mixture of monoammonium phosphate and diammonium phosphate.

[0040] Example 1 (the mass fraction of humic acid in the product is 1.5%)

[0041] Raw material indicators: neutralized slag - nitrogen 7.39% (dry basis), available phosphorus 31.19% (dry basis), water-soluble phosphorus 15.1% (dry basis), moisture 33.5%; slag acid phosphorus content 41%.

[0042] Mix 600g of neutralized slag (dry basis), 345g of slag acid (dry basis) and 15g of humic acid disintegrant evenly, introduce ammonia gas for neutralization reaction, control pH 5.0-6.0, dry and crush the reaction slurry, use a disc granulator for granulation, and control the spraying speed and water spraying amount according to the granulation situation during the granulation process. After granulation, dry in an oven at 60-150°C to control the moisture content of the fertilizer granules to less than 2.0%. After screening, take finished granules with a particle size of 1-4.0mm. The finished granules are as follows Figure 1 As shown, the disintegration time is 17min (fertilizer-water ratio 1:10), and the water-soluble disintegration is as follows Figure 2 As shown in Figure 2, the difference in the rate of water-soluble phosphorus fixation was reduced by 20.1% compared with the control.

[0043] Control group: No humic acid was added, and the rest of the steps were the same as above. Without humic acid, the disintegration rate was significantly slowed down.

[0044] Determination of the difference rate of water-soluble phosphorus fixation (calcium chloride precipitation method): The water-soluble phosphorus in the product reacts with calcium ions to form a precipitate. By determining the remaining water-soluble phosphorus, the water-soluble phosphorus fixation rate of the control binary fertilizer (the ratio of water-soluble phosphorus fixed by calcium ions to total water-soluble phosphorus) and the water-soluble phosphorus fixation rate of the binary fertilizer in the embodiment are calculated and analyzed. The difference between the two and the ratio of the former constitute the water-soluble phosphorus fixation difference rate. This value can be used to simulate the water-soluble phosphorus fixation of the fertilizer in the soil.

[0045] Product indicators of finished particles: as shown in Table 1

[0046] Table 1

[0047]

[0048] Example 2 (the mass fraction of humic acid in the product is 1.0%)

[0049] Raw material indicators: neutralized slag - nitrogen 7.39% (dry basis), available phosphorus 31.19% (dry basis), water-soluble phosphorus 15.1% (dry basis), moisture 33.5%; slag acid phosphorus content 41%.

[0050] 600g of neutralized slag (dry basis), 348g of slag acid (dry basis) and 10g of humic acid disintegrant were mixed evenly, ammonia was introduced for neutralization reaction, pH was controlled at 5.0-6.0, the reaction slurry was dried and crushed, and granulated using a disc granulator. During the granulation process, the spraying speed and water spraying amount were controlled according to the granulation situation. After granulation, the granules were dried in an oven at 60-150°C, and the moisture content of the fertilizer granules was controlled to be less than 2.0%. After screening, the finished granules with a particle size of 1-4.0mm were obtained, and the disintegration time was less than 30min (fertilizer-water ratio 1:10). Compared with the control, the difference rate of water-soluble phosphorus fixation was reduced by 16.0%.

[0051] Control group: No humic acid was added, and the rest of the steps were the same as above. Without humic acid, the disintegration rate was significantly slowed down.

[0052] Product indicators of finished particles: as shown in Table 2

[0053] Table 2

[0054]

[0055] Example 3 (the mass fraction of humic acid in the product is 1.0%)

[0056] Raw material indicators: neutralized slag - nitrogen 7.39% (dry basis), available phosphorus 31.19% (dry basis), water-soluble phosphorus 15.1% (dry basis), moisture 33.5%; slag acid phosphorus content 41%.

[0057] 690g of neutralized slag (dry basis), 270g of slag acid (dry basis) and 10g of humic acid disintegrant were mixed evenly, ammonia was introduced for neutralization reaction, pH was controlled at 5.0-6.0, the reaction slurry was dried and crushed, and granulated using a disc granulator. During the granulation process, the spraying speed and water spraying amount were controlled according to the granulation situation. After granulation, the granules were dried in an oven at 60-150°C, and the moisture content of the fertilizer granules was controlled to be less than 2.0%. After screening, the finished granules with a particle size of 1-4.0mm were obtained, and the disintegration time was less than 30min (fertilizer-water ratio 1:10). Compared with the control, the difference rate of water-soluble phosphorus fixation was reduced by 15.5%.

[0058] Control group: No humic acid was added, and the rest of the steps were the same as above. Without humic acid, the disintegration rate slowed down.

[0059] Product indicators of finished particles: as shown in Table 3

[0060] Table 3

[0061]

[0062] Example 4 (the mass fraction of humic acid in the product is 1.0%)

[0063] Raw material indicators: neutralized slag - nitrogen 7.39% (dry basis), available phosphorus 31.19% (dry basis), water-soluble phosphorus 15.1% (dry basis), moisture 33.5%; slag acid phosphorus content 41%.

[0064] 800g of neutralized slag (dry basis), 170g of slag acid (dry basis) and 10g of humic acid disintegrant were mixed evenly, ammonia was introduced for neutralization reaction, pH was controlled at 5.0-6.0, the reaction slurry was dried and crushed, and granulated using a disc granulator. During the granulation process, the spraying speed and water spraying amount were controlled according to the granulation situation. After granulation, the granules were dried in an oven at 60-150°C, and the moisture content of the fertilizer granules was controlled to be less than 2.0%. After screening, the finished granules with a particle size of 1-4.0mm were obtained, and the disintegration time was less than 30min (fertilizer-water ratio 1:10). Compared with the control, the difference rate of water-soluble phosphorus fixation was reduced by 15.2%.

[0065] Control group: No humic acid was added, and the rest of the steps were the same as above. Without humic acid, the disintegration rate was significantly slowed down.

[0066] Product indicators of finished particles: as shown in Table 4

[0067] Table 4

[0068]

[0069] Example 5 (the mass fraction of humic acid in the product is 1%, and the mass fraction of humic acid in the control group product is 0.5%)

[0070] Raw material indicators: neutralized slag - nitrogen 7.39% (dry basis), available phosphorus 31.19% (dry basis), water-soluble phosphorus 15.1% (dry basis), moisture 33.5%; slag acid phosphorus content 41%.

[0071] Mix 600g of neutralized slag (dry basis), 348g of slag acid (dry basis) and 10g of humic acid disintegrant evenly, introduce ammonia for neutralization reaction, control pH5.0-6.0, dry and crush the reaction slurry, use a disc granulator for granulation, and control the spraying speed and water spraying amount according to the granulation situation during the granulation process. After granulation, dry in an oven at 60-150°C to control the moisture content of the fertilizer granules to less than 2.0%. After screening, take finished granules with a particle size of 1-4.0mm, the disintegration time is less than 30min (fertilizer-water ratio 1:10), and the water-soluble disintegration is as follows: Figure 3 As shown in B. Compared with the control, the difference rate of water-soluble phosphorus fixation was reduced by 11.7%.

[0072] Control group: 5g humic acid, the rest of the steps are the same as above. Humic acid content 0.5%, the disintegration speed is significantly slowed down, the disintegration time is 40 minutes, the water-soluble disintegration is as follows Figure 3 As shown in A.

[0073] Product indicators of finished particles: as shown in Table 5

[0074] Table 5

[0075]

[0076] It can be seen from Table 1, Table 2, Table 3, Table 4 and Table 5 that compared with the nitrogen-phosphorus binary fertilizer added with 0.5% humic acid disintegrator, the binary fertilizer added with 1.0% humic acid disintegrated faster.

[0077] From Table 1, it can be seen that when the humic acid content in the product is 1.5%, the disintegration time of the nitrogen-phosphorus binary fertilizer is slightly faster than that of the humic acid content of 1.0%; from Table 5, it can be seen that when the humic acid content is 0.5%, the disintegration time of the nitrogen-phosphorus binary fertilizer is significantly slower. Considering the comprehensive cost and disintegration effect, the preferred amount of humic acid is 1.0-1.5%.

[0078] Comparative Example 6: Testing with other disintegrants (mass fraction of disintegrant in the product is 1.0%)

[0079] Raw material indicators: neutralized slag - nitrogen 7.39% (dry basis), available phosphorus 31.19% (dry basis), water-soluble phosphorus 15.1% (dry basis), moisture 33.5%; slag acid phosphorus content 41%.

[0080] 600g of neutralized slag (dry basis), 348g of slag acid (dry basis) and 10g of humic acid disintegrant were mixed evenly, ammonia was introduced for neutralization reaction, pH was controlled at 5.0-6.0, the reaction slurry was dried and crushed, and granulated using a disc granulator. During the granulation process, the spraying speed and water spraying amount were controlled according to the granulation situation. After granulation, the granules were dried in an oven at 60-100°C, and the moisture content of the fertilizer granules was controlled to be less than 2.0%. After screening, the finished granules with a particle size of 1-4.0mm were obtained, and the disintegration time was less than 30min (fertilizer-water ratio 1:10). Compared with the control, the difference rate of water-soluble phosphorus fixation was reduced by 16.0%.

[0081] Control group: ammonium carbonate and expanded vermiculite were used to replace humic acid, and the rest of the steps were the same as above. The disintegration rate of ammonium carbonate and expanded vermiculite was relatively slow.

[0082] Product indicators of finished particles: as shown in Table 6

[0083] Table 6

[0084]

[0085]

[0086] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0087] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preparing nitrogen-phosphorus binary fertilizer using humic acid as a disintegrator, characterized in that: include: The neutralized slag, slag acid and humic acid are mixed and treated; and subjecting the mixed treatment product to a neutralization reaction with ammonia to obtain a slurry; The slurry is granulated and dried to obtain the nitrogen-phosphorus binary fertilizer.

2. The method according to claim 1, characterized in that The mass ratio of the neutralized slag to the slag acid is (550-800):(150-400).

3. The method according to claim 1, characterized in that: The mass content of humic acid in the mixed treatment product is 1.0-1.5%.

4. The method according to claim 1, characterized in that The neutralization reaction is carried out at a pH of 5.0 to 6.

0.

5. The method according to claim 1, characterized in that The humic acid is one or more of plant-derived humic acid and mineral-derived humic acid.

6. The method according to claim 5, characterized in that The molecular weight of the humic acid is 100,000-1,000,000.

7. The method according to claim 1, characterized in that The granulation and drying process is carried out in a granulator, the head temperature of the granulator is 400-500°C, and the tail temperature of the granulator is 60-100°C.

8. The method according to claim 7, characterized in that The granulation is performed by spray granulation or coating granulation.

9. The method according to claim 8, characterized in that The water content of the nitrogen-phosphorus binary fertilizer particles after the granulation and drying treatment is less than 2.5%.

10. The method according to claim 9, characterized in that The water content of the nitrogen-phosphorus binary fertilizer particles after the granulation and drying treatment is less than 2%.

11. The method according to claim 1, characterized in that: The granulation and drying process further comprises: The granulation and drying products are sequentially cooled, screened, and subjected to anti-caking treatment to obtain nitrogen-phosphorus binary fertilizer granules.

12. The method according to claim 11, characterized in that The temperature of the granulation and drying product after cooling is 30-50°C.

13. The method according to claim 12, characterized in that The temperature of the granulation and drying product after cooling is 30-40°C.

14. The method according to claim 11, characterized in that The particle size of the granulated and dried product after the screening is 1 to 4.0 mm.

15. A nitrogen-phosphorus binary fertilizer, characterized in that: The method is used to prepare the composition according to any one of claims 1 to 14.

16. The nitrogen-phosphorus binary fertilizer according to claim 15, characterized in that The disintegration time of the nitrogen-phosphorus binary fertilizer in water is no more than 30 minutes.

17. The nitrogen-phosphorus dual fertilizer according to claim 16, characterized in that The disintegration time of the nitrogen-phosphorus binary fertilizer in water is 10 to 30 minutes.

18. The nitrogen-phosphorus dual fertilizer according to claim 15, characterized in that The total nitrogen content of the nitrogen-phosphorus binary is not less than 6.0%, the available phosphorus is not less than 30.0%, and the water-soluble phosphorus is not less than 18.0%.

19. A blended fertilizer, characterized in that: The invention comprises the nitrogen-phosphorus binary fertilizer as described in any one of claims 15 to 18.

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