A compound fertilizer containing polyglutamic acid and polyphosphate and a method for preparing the same

Abstract

The present application relates to a kind of composite fertilizer containing polyglutamic acid and polyphosphate and its preparation method, belong to the technical field of compound fertilizer.The present application utilizes oligomeric ammonium polyphosphate as the main source of phosphorus element in fertilizer, on the one hand, it has more nutrient content than traditional phosphorus fertilizer, and the structure has high phosphorus oxygen ratio, strong water solubility, on the other hand, it has slow-release property after being applied to soil, can slowly generate orthophosphate and be absorbed and utilized by crops, compared with traditional phosphorus fertilizer, the fertilizer efficiency period is longer, can greatly improve the utilization rate of phosphorus element of crops, promote yield.At the same time, polyglutamic acid is also used for matching, through the chelation of polyglutamic acid during fertilization, the adsorption of calcium, magnesium, aluminum and other metal ions in soil solution is realized, so that the phosphorus in fertilizer is not easy to lose and be fixed in soil, further promote the utilization rate of phosphorus element, reduce the probability of soil phosphorus leaching.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of compound fertilizer, and particularly relates to a compound fertilizer containing polyglutamic acid and polyphosphate and a preparation method thereof. BACKGROUND

[0002] Phosphorus is an important nutrient element necessary for crop growth, which has a very important influence on various physiological activities of crops. On the one hand, it can promote the root development of crops and improve the absorption capacity of crops to soil nutrients. On the other hand, it participates in energy metabolism and protein synthesis in crops. Therefore, in agricultural production, it is particularly important to apply fertilizers containing phosphorus fertilizer.

[0003] However, the utilization rate of phosphorus fertilizer on the market is generally low. This is because after the phosphorus fertilizer is applied to the soil, it is easy to react with metal ions such as calcium, magnesium and aluminum in the soil solution to form phosphate precipitates and be fixed in the soil. Only a small part of the phosphorus fertilizer can be effectively utilized by crops, thereby reducing the yield of crops, and in the long run, increasing the probability of soil phosphorus leaching.

[0004] Therefore, the phosphorus fertilizer in the current fertilizer still has many defects and needs to be improved. SUMMARY

[0005] In view of the problems in the prior art, the purpose of the present application is to provide a compound fertilizer containing polyglutamic acid and polyphosphate and a preparation method thereof. The present application uses oligomeric ammonium polyphosphate as the main source of phosphorus element in fertilizer. On the one hand, it has more nutrient content than traditional phosphorus fertilizer, and the phosphorus oxygen ratio in the structure is high and the water solubility is strong. On the other hand, it has a slow-release property after being applied to the soil, and can slowly generate orthophosphate to be absorbed and utilized by crops. Compared with traditional phosphorus fertilizer, the fertilizer efficiency period is longer, which can greatly improve the utilization rate of phosphorus element by crops and promote the yield. At the same time, polyglutamic acid is also used for matching. Through the chelation of polyglutamic acid during fertilization, the adsorption of metal ions such as calcium, magnesium and aluminum in the soil solution is realized, so that the phosphorus in the fertilizer is not easy to be lost and fixed in the soil, further improving the utilization rate of phosphorus element and reducing the probability of soil phosphorus leaching.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A compound fertilizer containing polyglutamic acid and polyphosphate, which is prepared from 80-90 parts by weight of polyphosphate, 50-60 parts by weight of urea, 60-70 parts by weight of potassium chloride, 20-30 parts by weight of fulvic acid, 0.5-1 part by weight of nitrification inhibitor, 20-30 parts by weight of polyglutamic acid, 3-5 parts by weight of trace element mixture and 130-140 parts by weight of deionized water.

[0008] As a preferred technical solution of the present application, the polyphosphate is oligomeric ammonium polyphosphate.

[0009] Further, the oligomeric ammonium polyphosphate is prepared by the following steps:

[0010] Step a: heat 45-50 parts by weight of phosphoric acid solution to 50-60℃, keep warm, and reserve;

[0011] Step b: mix 50-60 parts by weight of urea with 10-15 parts by weight of solid phosphoric acid, then treat under microwave with power of 450-500W for 15-20min to obtain a molten liquid;

[0012] Step c: continue to maintain under the action of microwave to add phosphoric acid solution to the molten liquid, mix for 1-3min, stop microwave, then start the first temperature rise under stirring in ammonia atmosphere until the reaction material starts to foam, then keep warm to obtain mixture a;

[0013] Step d: after mixture a stops foaming, stop stirring, then start the second temperature rise to 120-130℃ and keep warm for 30-40min to obtain the product;

[0014] Step e: naturally cool the product to room temperature, crush, and the preparation is completed.

[0015] Preferably, the concentration of the phosphoric acid solution in step a is 65-70%.

[0016] Preferably, the flow rate of the ammonia atmosphere in step c is 2-4L / h.

[0017] Preferably, the first temperature rise in step c is controlled at a rate of 2-3℃ / min.

[0018] Preferably, the second temperature rise in step d is controlled at a rate of 1-2℃ / min.

[0019] As a preferred technical solution of the present application, the nitrification inhibitor is dicyandiamide.

[0020] As a preferred technical solution of the present application, the microelement mixture is mixed by 5-6 parts by weight of zinc sulfate, 4-5 parts by weight of manganese sulfate, 4-5 parts by weight of copper sulfate, 2-3 parts by weight of ammonium molybdate and 2-3 parts by weight of boric acid.

[0021] A preparation method of a compound fertilizer containing polyglutamic acid and polyphosphate, the preparation method comprising the following steps:

[0022] (1) mix deionized water with polyphosphate by stirring for 3-5min, then add a microelement mixture, and stir at 30-35℃ for 15-20min to obtain component A;

[0023] (2) Add urea, potassium chloride, fulvic acid and nitration inhibitor to component A, then stir at room temperature for 5-10 minutes to mix, and finally add polyglutamic acid and stir for 20-30 minutes to complete the preparation.

[0024] The beneficial effects of this invention are:

[0025] (1) This invention creatively utilizes ammonium oligophosphate as the main source of phosphorus in fertilizers. On the one hand, it has a higher nutrient content than traditional phosphate fertilizers, and its structure has a high phosphorus-to-oxygen ratio and strong water solubility. On the other hand, it has slow-release properties after being applied to the soil, and can slowly generate orthophosphates that can be absorbed and utilized by crops. Compared with traditional phosphate fertilizers, it has a longer fertilizer effect period, which can greatly improve the utilization rate of phosphorus by crops and promote yield. At the same time, it also uses polyglutamic acid in combination. During fertilization, the chelating effect of polyglutamic acid can achieve the adsorption of metal ions such as calcium, magnesium, and aluminum in the soil solution, so that the phosphorus in the fertilizer is not easily lost and fixed in the soil, further promoting the utilization rate of phosphorus and reducing the probability of phosphorus leaching in the soil.

[0026] (2) This invention creatively improves upon existing methods for preparing oligomeric ammonium polyphosphate. In this invention, urea and solid phosphoric acid are first mixed, resulting in a mixture with a lower melting point than urea alone. Then, microwave treatment is used to obtain a molten liquid, which serves as the subsequent reactant. This process not only solves the problems of uneven reaction and agglomeration associated with solid-phase urea reactions but also avoids potential condensation reactions of urea itself during the melting process. Furthermore, the added phosphoric acid solution dissolves and mixes the molten phosphoric acid, and after heating, a liquid-liquid polymerization reaction is carried out to prepare oligomeric ammonium polyphosphate. Compared to existing methods where solid-phase urea is directly dissolved in phosphoric acid solution before reaction, this invention achieves a more thorough reaction, shortens polymerization time, lowers polymerization temperature, effectively reduces side reactions, and produces ammonium polyphosphate with a lower degree of polymerization, making it more suitable as a primary source of phosphate fertilizer in compound fertilizers.

[0027] (3) In the preparation method of compound fertilizer, the present invention first dissolves ammonium oligophosphate in deionized water, and then adds a mixture of trace elements for dissolution and mixing. This allows some of the ammonium oligophosphate to form a complex with the metal ions therein, forming an ammonium polyphosphate complex. Compared with inorganic salts in the prior art, the ammonium polyphosphate complex can improve the activity of the complexed trace elements such as Zn and Mn, further promoting crop absorption and utilization. At the same time, after complexation and mixing with polyglutamic acid, the adsorption effect of polyglutamic acid on metal ions can be effectively avoided, achieving coexistence in the compound fertilizer and reducing mutual influence. Detailed Implementation

[0028] In order to further clarify the technical means adopted by the present application and the effects thereof, and to achieve the predetermined object of the present application, the following describes the specific embodiments, structures, features and effects of the present application in detail.

[0029] Example 1

[0030] A compound fertilizer containing polyglutamic acid and polyphosphate, the compound fertilizer being prepared from 80 parts by weight of polyphosphate, 50 parts by weight of urea, 60 parts by weight of potassium chloride, 20 parts by weight of fulvic acid, 0.5 parts by weight of nitrification inhibitor, 20 parts by weight of polyglutamic acid, 3 parts by weight of trace element mixture and 130 parts by weight of deionized water.

[0031] The polyphosphate is oligomeric ammonium polyphosphate.

[0032] The oligomeric ammonium polyphosphate is prepared by the following steps:

[0033] Step a: heating 45 parts by weight of phosphoric acid solution to 50℃, keeping warm, and reserving;

[0034] Step b: mixing 50 parts by weight of urea with 10 parts by weight of solid phosphoric acid, and then treating under microwave with a power of 450W for 15min to obtain a molten liquid;

[0035] Step c: continuing to maintain under the action of microwave to add phosphoric acid solution to the molten liquid, stirring for 1min to mix, stopping the microwave, and then starting the first temperature rise under stirring in an ammonia atmosphere until the reaction material starts to foam, and then keeping warm to obtain a mixture a;

[0036] Step d: after the mixture a stops foaming, stopping stirring, and then starting the second temperature rise to 120℃ and keeping warm for 30min to obtain a product;

[0037] Step e: naturally cooling the product to room temperature, and crushing, to complete the preparation.

[0038] The concentration of the phosphoric acid solution in step a is 65%.

[0039] The flow rate of the ammonia atmosphere in step c is 2L / h.

[0040] The first temperature rise in step c is controlled at a rate of 2℃ / min.

[0041] The second temperature rise in step d is controlled at a rate of 1℃ / min.

[0042] The nitrification inhibitor is dicyandiamide.

[0043] The trace element mixture is mixed by 5 parts by weight of zinc sulfate, 4 parts by weight of manganese sulfate, 4 parts by weight of copper sulfate, 2 parts by weight of ammonium molybdate and 2 parts by weight of boric acid.

[0044] A preparation method of a compound fertilizer containing polyglutamic acid and polyphosphate, the preparation method comprising the following steps:

[0045] (1) mixing deionized water with polyphosphate by stirring for 3 min, then adding a trace element mixture, stirring at 30℃ for 15 min to obtain component A;

[0046] (2) adding urea, potassium chloride, fulvic acid and nitrification inhibitor to component A, then mixing by stirring at room temperature for 5 min, and finally adding polyglutamic acid and stirring for 20 min to complete the preparation.

[0047] Example 2

[0048] A compound fertilizer containing polyglutamic acid and polyphosphate, the compound fertilizer being prepared from 90 parts by weight of polyphosphate, 60 parts by weight of urea, 70 parts by weight of potassium chloride, 30 parts by weight of fulvic acid, 1 part by weight of nitrification inhibitor, 30 parts by weight of polyglutamic acid, 5 parts by weight of trace element mixture and 140 parts by weight of deionized water.

[0049] The polyphosphate is oligomeric ammonium polyphosphate.

[0050] The oligomeric ammonium polyphosphate is prepared by the following steps:

[0051] Step a: heating 50 parts by weight of a phosphoric acid solution to 60℃, keeping warm, and reserving;

[0052] Step b: mixing 60 parts by weight of urea with 15 parts by weight of solid phosphoric acid, then treating under microwave with a power of 500W for 20 min to obtain a molten liquid;

[0053] Step c: continuously adding the phosphoric acid solution to the molten liquid under the action of microwave, mixing by stirring for 3 min, stopping the microwave, then starting the first temperature rise while stirring under ammonia atmosphere until the reaction material starts to foam, then keeping warm to obtain mixture a;

[0054] Step d: after mixture a stops foaming, stopping stirring, then starting the second temperature rise to 130℃ and keeping warm for 40 min to obtain the product;

[0055] Step e: naturally cooling the product to room temperature, crushing, to complete the preparation.

[0056] The concentration of the phosphoric acid solution in step a is 70%.

[0057] The flow rate of the ammonia atmosphere in step c is 4 L / h.

[0058] The rate of the first temperature increase in step c is controlled at 3°C / min.

[0059] The rate of the second temperature increase in step d is controlled at 2°C / min.

[0060] The nitrification inhibitor is dicyandiamide.

[0061] The trace element mixture is prepared by mixing 6 parts by weight of zinc sulfate, 5 parts by weight of manganese sulfate, 5 parts by weight of copper sulfate, 3 parts by weight of ammonium molybdate and 3 parts by weight of boric acid.

[0062] A method for preparing a compound fertilizer containing polyglutamic acid and polyphosphate, the method comprising the following steps:

[0063] (1) mixing deionized water with polyphosphate by stirring for 5 min, then adding a trace element mixture, stirring for 20 min at 35°C to obtain component A;

[0064] (2) adding urea, potassium chloride, fulvic acid and a nitrification inhibitor to component A, then mixing by stirring for 10 min at room temperature, and finally adding polyglutamic acid and stirring for 30 min to complete the preparation.

[0065] Example 3

[0066] A compound fertilizer containing polyglutamic acid and polyphosphate, the compound fertilizer being prepared from 85 parts by weight of polyphosphate, 55 parts by weight of urea, 65 parts by weight of potassium chloride, 25 parts by weight of fulvic acid, 0.7 parts by weight of a nitrification inhibitor, 25 parts by weight of polyglutamic acid, 4 parts by weight of a trace element mixture and 135 parts by weight of deionized water.

[0067] The polyphosphate is oligomeric ammonium polyphosphate.

[0068] The oligomeric ammonium polyphosphate is prepared by the following steps:

[0069] Step a: heating 47 parts by weight of a phosphoric acid solution to 55°C and keeping the temperature constant for standby;

[0070] Step b: mixing 55 parts by weight of urea with 13 parts by weight of solid phosphoric acid, then treating under microwaves with a power of 470 W for 18 min to obtain a molten liquid;

[0071] Step c: continuing to maintain the molten liquid under the action of microwaves, adding the phosphoric acid solution and mixing by stirring for 2 min, stopping the microwaves, then starting the first temperature increase under stirring in an ammonia atmosphere until the reaction material starts to foam, then keeping the temperature constant to obtain a mixture a;

[0072] Step d: after the mixture a stops foaming, stop stirring, then start the second temperature rising to 125℃ and keep for 35 min, to obtain the product;

[0073] Step e: cool the product to room temperature naturally, and crush, to complete the preparation.

[0074] The concentration of the phosphoric acid solution in step a is 68%.

[0075] The flow rate of the ammonia atmosphere in step c is 3 L / h.

[0076] The rate of the first temperature rising in step c is controlled at 2.5℃ / min.

[0077] The rate of the second temperature rising in step d is controlled at 1.5℃ / min.

[0078] The nitrification inhibitor is dicyanamide.

[0079] The trace element mixture is prepared by mixing 5.5 parts by weight of zinc sulfate, 4.5 parts by weight of manganese sulfate, 4.5 parts by weight of copper sulfate, 2.5 parts by weight of ammonium molybdate and 2.5 parts by weight of boric acid.

[0080] A preparation method of a compound fertilizer containing polyglutamic acid and polyphosphate, the preparation method comprising the following steps:

[0081] (1) mixing deionized water with polyphosphate by stirring for 4 min, then adding a trace element mixture, and stirring at 32℃ for 17 min to obtain component A;

[0082] (2) adding urea, potassium chloride, fulvic acid and a nitrification inhibitor to component A, then mixing by stirring at room temperature for 8 min, and finally adding polyglutamic acid and stirring for 25 min, to complete the preparation.

[0083] Comparative Example 1

[0084] A compound fertilizer containing polyglutamic acid and polyphosphate, the compound fertilizer being prepared from 80 parts by weight of polyphosphate, 50 parts by weight of urea, 60 parts by weight of potassium chloride, 20 parts by weight of fulvic acid, 0.5 parts by weight of a nitrification inhibitor, 20 parts by weight of polyglutamic acid, 3 parts by weight of a trace element mixture and 130 parts by weight of deionized water.

[0085] The polyphosphate is oligomeric ammonium polyphosphate.

[0086] The oligomeric ammonium polyphosphate is prepared by the following steps:

[0087] Step a: heating 45 parts by weight of a phosphoric acid solution to 50℃ and keeping, for standby;

[0088] Step b: 50 parts by weight of urea is mixed with 10 parts by weight of solid phosphoric acid to obtain component A;

[0089] Step c: phosphoric acid solution is added to component A, stirred for 1 min, mixed, and then the first temperature rise is started under ammonia atmosphere while stirring until the reaction material starts to foam, followed by temperature maintenance to obtain mixture A;

[0090] Step d: after mixture A stops foaming, the stirring is stopped, and then the second temperature rise to 120°C is started and maintained for 30 min to obtain the product;

[0091] Step e: the product is naturally cooled to room temperature, and then crushed to complete the preparation.

[0092] The concentration of the phosphoric acid solution in step a is 65%.

[0093] The flow rate of the ammonia atmosphere in step c is 2 L / h.

[0094] The rate of the first temperature rise in step c is controlled at 2°C / min.

[0095] The rate of the second temperature rise in step d is controlled at 1°C / min.

[0096] The nitrification inhibitor is dicyandiamide.

[0097] The trace element mixture is prepared by mixing 5 parts by weight of zinc sulfate, 4 parts by weight of manganese sulfate, 4 parts by weight of copper sulfate, 2 parts by weight of ammonium molybdate, and 2 parts by weight of boric acid.

[0098] A preparation method of a compound fertilizer containing polyglutamic acid and polyphosphate, the preparation method comprising the following steps:

[0099] (1) Deionized water is mixed with polyphosphate by stirring for 3 min, and then a trace element mixture is added, stirred for 15 min at 30°C to obtain component A;

[0100] (2) Urea, potassium chloride, fulvic acid, and a nitrification inhibitor are added to component A, stirred and mixed for 5 min at room temperature, and finally polyglutamic acid is added and stirred for 20 min to complete the preparation.

[0101] Comparative Example 2

[0102] A compound fertilizer containing polyglutamic acid, the compound fertilizer being prepared from 80 parts by weight of diammonium hydrogen phosphate, 50 parts by weight of urea, 60 parts by weight of potassium chloride, 20 parts by weight of fulvic acid, 0.5 parts by weight of a nitrification inhibitor, 20 parts by weight of polyglutamic acid, 3 parts by weight of a trace element mixture, and 130 parts by weight of deionized water.

[0103] The nitrification inhibitor is dicyandiamide.

[0104] The trace element mixture is mixed by 5 parts by weight of zinc sulfate, 4 parts by weight of manganese sulfate, 4 parts by weight of copper sulfate, 2 parts by weight of ammonium molybdate and 2 parts by weight of boric acid.

[0105] A preparation method of a compound fertilizer containing polyglutamic acid, the preparation method comprising the following steps:

[0106] (1) mixing deionized water with diammonium hydrogen phosphate by stirring for 3 min, then adding a trace element mixture, stirring at 30℃ for 15 min to obtain component A;

[0107] (2) adding urea, potassium chloride, fulvic acid and nitrification inhibitor to component A, then mixing by stirring at room temperature for 5 min, and finally adding polyglutamic acid and stirring for 20 min to complete the preparation.

[0108] Comparative Example 3

[0109] A compound fertilizer containing polyphosphate, the compound fertilizer being prepared from 80 parts by weight of polyphosphate, 50 parts by weight of urea, 60 parts by weight of potassium chloride, 20 parts by weight of fulvic acid, 0.5 parts by weight of nitrification inhibitor, 3 parts by weight of trace element mixture and 130 parts by weight of deionized water.

[0110] The polyphosphate is oligomeric ammonium polyphosphate.

[0111] The oligomeric ammonium polyphosphate is prepared by the following steps:

[0112] Step a: heating 45 parts by weight of a phosphoric acid solution to 50℃, keeping warm, and reserving;

[0113] Step b: mixing 50 parts by weight of urea with 10 parts by weight of solid phosphoric acid, then treating under microwave with a power of 450W for 15 min to obtain a molten liquid;

[0114] Step c: continuing to maintain under the action of microwave to add the phosphoric acid solution to the molten liquid, mixing by stirring for 1 min, stopping the microwave, then starting the first temperature rise while stirring under ammonia atmosphere until the reaction material starts to foam, then keeping warm to obtain mixture a;

[0115] Step d: after mixture a stops foaming, stopping stirring, then starting the second temperature rise to 120℃ and keeping warm for 30 min to obtain the product;

[0116] Step e: naturally cooling the product to room temperature, crushing, to complete the preparation.

[0117] The concentration of the phosphoric acid solution in step a is 65%.

[0118] The flow rate of the ammonia atmosphere in step c is 2 L / h.

[0119] The rate of the first temperature increase in step c is controlled at 2°C / min.

[0120] The rate of the second temperature increase in step d is controlled at 1°C / min.

[0121] The nitrification inhibitor is dicyandiamide.

[0122] The trace element mixture is mixed from 5 parts by weight of zinc sulfate, 4 parts by weight of manganese sulfate, 4 parts by weight of copper sulfate, 2 parts by weight of ammonium molybdate and 2 parts by weight of boric acid.

[0123] A preparation method of a compound fertilizer containing polyphosphate, the preparation method comprising the following steps:

[0124] (1) mixing deionized water and polyphosphate by stirring for 3 min, then adding a trace element mixture, stirring at 30°C for 15 min to obtain component A;

[0125] (2) adding urea, potassium chloride, fulvic acid and a nitrification inhibitor to component A, then mixing by stirring at room temperature for 25 min to complete the preparation.

[0126] Comparative Example 4

[0127] A compound fertilizer containing polyglutamic acid and polyphosphate, the compound fertilizer being prepared from 80 parts by weight of polyphosphate, 50 parts by weight of urea, 60 parts by weight of potassium chloride, 20 parts by weight of fulvic acid, 0.5 parts by weight of a nitrification inhibitor, 20 parts by weight of polyglutamic acid, 3 parts by weight of a trace element mixture and 130 parts by weight of deionized water.

[0128] The polyphosphate is oligomeric ammonium polyphosphate.

[0129] The oligomeric ammonium polyphosphate is prepared by the following steps:

[0130] Step a: heating 45 parts by weight of a phosphoric acid solution to 50°C, keeping warm, ready for use;

[0131] Step b: mixing 50 parts by weight of urea with 10 parts by weight of solid phosphoric acid, then treating under microwaves at a power of 450 W for 15 min to obtain a molten liquid;

[0132] Step c: continuing to maintain under the action of microwaves to add the phosphoric acid solution to the molten liquid, stirring for 1 min to mix, stopping the microwaves, then starting the first temperature increase under stirring in an ammonia atmosphere until the reaction material starts to foam, then keeping warm to obtain a mixture a;

[0133] Step d: after the mixture a stops foaming, stop stirring, then start the second temperature rising to 120℃ and keep for 30 min, to obtain the product;

[0134] Step e: cool the product to room temperature naturally, and crush, to complete the preparation.

[0135] The concentration of the phosphoric acid solution in step a is 65%.

[0136] The flow rate of the ammonia atmosphere in step c is 2 L / h.

[0137] The rate of the first temperature rising in step c is controlled at 2℃ / min.

[0138] The rate of the second temperature rising in step d is controlled at 1℃ / min.

[0139] The nitrification inhibitor is dicyandiamide.

[0140] The trace element mixture is mixed by 5 parts by weight of zinc sulfate, 4 parts by weight of manganese sulfate, 4 parts by weight of copper sulfate, 2 parts by weight of ammonium molybdate and 2 parts by weight of boric acid.

[0141] A preparation method of a compound fertilizer containing polyglutamic acid and polyphosphate, the preparation method comprising the following steps:

[0142] (1) mixing deionized water with polyphosphate by stirring for 3 min, then adding polyglutamic acid, stirring at 30℃ for 15 min to obtain component A;

[0143] (2) adding urea, potassium chloride, fulvic acid and nitrification inhibitor into component A, then mixing by stirring at room temperature for 5 min, and finally adding trace element mixture and stirring for 20 min, to complete the preparation.

[0144] Comparative Example 5

[0145] A compound fertilizer prepared from 80 parts by weight of diammonium hydrogen phosphate, 50 parts by weight of urea, 60 parts by weight of potassium chloride, 20 parts by weight of fulvic acid, 0.5 parts by weight of nitrification inhibitor, 3 parts by weight of trace element mixture and 130 parts by weight of deionized water.

[0146] The nitrification inhibitor is dicyandiamide.

[0147] The trace element mixture is mixed by 5 parts by weight of zinc sulfate, 4 parts by weight of manganese sulfate, 4 parts by weight of copper sulfate, 2 parts by weight of ammonium molybdate and 2 parts by weight of boric acid.

[0148] A preparation method of a compound fertilizer, the preparation method comprising the following steps:

[0149] (1)Deionized water and diammonium hydrogen phosphate were stirred for 3 min, then trace element mixture was added, stirred for 15 min at 30°C, to obtain component A;

[0150] (2)Urea, potassium chloride, fulvic acid and nitrification inhibitor were added to component A, then stirred for 25 min at room temperature to complete preparation.

[0151] Test Example 1

[0152] Oligomeric ammonium polyphosphate quality test:

[0153] The oligomeric ammonium polyphosphate prepared in Examples 1-3 and Comparative Example 1 was determined for its phosphorus pentoxide content, polymerization rate, total nitrogen content, biuret content and other indicators according to the standard Q / CQS 02-2018 of agricultural polyphosphate, so as to determine the quality of the prepared oligomeric ammonium polyphosphate.

[0154] Table 1. Oligomeric ammonium polyphosphate quality test results

[0155]

[0156]

[0157] Test Example 2

[0158] Compound fertilizer effect test:

[0159] Winter wheat was taken as a typical representative, and the compound fertilizers prepared in Examples 1-3 and Comparative Examples 1-5 were used for winter wheat planting. During the period, except that the compound fertilizers used were different, the various conditions such as fertilization frequency, watering amount, sunshine time and the like were kept consistent, and at the same time, Comparative Example 5 was taken as a control group to determine the yield increase, so as to illustrate the effect of the compound fertilizer.

[0160] Table 2. Compound fertilizer effect test results

[0161]

[0162] Through the comparison of Examples 1-3, Comparative Examples 1-5 and Test Examples 1-2, it can be seen that:

[0163] The difference between Comparative Example 1 and Example 1 is that the solid-phase urea is dissolved into hot phosphoric acid solution before reaction in the preparation method of oligomeric ammonium polyphosphate.

[0164] The difference between Comparative Example 2 and Example 1 is that diammonium hydrogen phosphate is used instead of polyphosphate.

[0165] The difference between Comparative Example 3 and Example 1 is that polyglutamic acid is not added.

[0166] The difference between Comparative Example 4 and Example 1 is that in the preparation method of the compound fertilizer, the oligomeric ammonium polyphosphate is not used to complex with the metal ions in the trace element mixture.

[0167] The difference between Comparative Example 5 and Example 1 is that diammonium hydrogen phosphate is used instead of polyphosphate, and polyglutamic acid is not added.

[0168] It can be seen from the comparison of Examples 1-3, Comparative Example 1 and Test Example 1 that under the reaction conditions of the present application, the oligomeric ammonium polyphosphate prepared has high quality, and all indexes are within the standard range, and even far exceed (better than) the standard requirements. Although most of the indexes of Comparative Example 1 are within the standard range, the phosphorus and nitrogen contents are low, and the effect is limited in actual application.

[0169] It can be seen from the comparison of Examples 1-3, Comparative Examples 1-5 and Test Example 2 that the compound fertilizer prepared in the present application has better effect when applied in planting, and plays a good promoting role on the yield of crops.

[0170] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any modification, equivalent change and modification of the above embodiments according to the technical essence of the present application, which does not depart from the technical solution of the present application, still belongs to the scope of the technical solution of the present application.

Claims

1. A compound fertilizer containing polyglutamic acid and polyphosphate, characterized by: The compound fertilizer is prepared from 80-90 parts by weight of polyphosphate, 50-60 parts by weight of urea, 60-70 parts by weight of potassium chloride, 20-30 parts by weight of fulvic acid, 0.5-1 part by weight of nitrification inhibitor, 20-30 parts by weight of polyglutamic acid, 3-5 parts by weight of trace element mixture and 130-140 parts by weight of deionized water; The polyphosphate is oligomeric ammonium polyphosphate; The oligomeric ammonium polyphosphate is prepared by the following steps: Step a: heating 45-50 parts by weight of phosphoric acid solution to 50-60℃, and keeping warm for standby; Step b: mixing 50-60 parts by weight of urea with 10-15 parts by weight of solid phosphoric acid, and then treating under microwave with a power of 450-500W for 15-20min to obtain a molten liquid; Step c: continuing to maintain under the action of microwave to add phosphoric acid solution to the molten liquid, stirring for 1-3min, mixing, stopping the microwave, and then starting the first temperature rise under the stirring and ammonia atmosphere until the reaction material starts to foam, and then keeping warm to obtain a mixture a; Step d: after the mixture a stops foaming, stopping stirring, and then starting the second temperature rise to 120-130℃ and keeping warm for 30-40min to obtain a product; Step e: naturally cooling the product to room temperature, and crushing, thereby completing the preparation; The concentration of the phosphoric acid solution in step a is 65-70%; The flow rate of the ammonia atmosphere in step c is 2-4L / h; The first temperature rise in step c is controlled at a rate of 2-3℃ / min; The second temperature rise in step d is controlled at a rate of 1-2℃ / min.

2. The compound fertilizer containing polyglutamic acid and polyphosphate according to claim 1, characterized by: The nitrification inhibitor is dicyandiamide.

3. The compound fertilizer containing polyglutamic acid and polyphosphate according to claim 1, characterized by: The trace element mixture is prepared by mixing 5-6 parts by weight of zinc sulfate, 4-5 parts by weight of manganese sulfate, 4-5 parts by weight of copper sulfate, 2-3 parts by weight of ammonium molybdate and 2-3 parts by weight of boric acid.

4. A method for the production of a compound fertilizer containing polyglutamic acid and polyphosphate according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: (1) mixing deionized water with polyphosphate by stirring for 3-5min, and then adding the trace element mixture, and stirring at 30-35℃ for 15-20min to obtain component A; (2) adding urea, potassium chloride, fulvic acid and nitrification inhibitor to component A, and then mixing by stirring at room temperature for 5-10min, and finally adding polyglutamic acid and stirring for 20-30min, thereby completing the preparation.

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