A water-soluble granular fertilizer for a drip irrigation system and a method of preparing the same

Abstract

The application belongs to the technical field of water-soluble granular fertilizer, and particularly relates to a water-soluble granular fertilizer suitable for a drip irrigation system and a preparation method thereof. The water-soluble granular fertilizer comprises the following raw materials in parts by weight: nitrogen fertilizer 20-40 parts, phosphorus fertilizer 15-30 parts, potassium fertilizer 20-40 parts, organic matter 10-20 parts, soybean polypeptide 0.5-1 part, adhesive 1-4 parts, and anti-sticking agent 2-5 parts. The adhesive comprises isomalt, dopamine hydrochloride and water. The anti-sticking agent comprises rhamnolipid, acidic polysaccharide, polyethylene glycol-poly (caprolactone) copolymer and water. The water-soluble granular fertilizer provided by the application has a high yield, a low caking rate and a high dissolution speed.

Description

Technical Field

[0001] This invention belongs to the field of water-soluble granular fertilizer technology, specifically relating to a water-soluble granular fertilizer suitable for drip irrigation systems and its preparation method. Background Technology

[0002] Fertilization via irrigation systems is a water and fertilizer integration technology that allows crops to absorb water and nutrients simultaneously. Compared with conventional fertilization, this technology has the advantages of precise fertilization, significantly improved fertilizer utilization, reduced labor costs, improved soil conditions, enhanced crop resilience to disaster risks, and environmental protection. It is widely used in crops such as grains (corn, wheat, potatoes), fruits (grapes, citrus, bananas, dragon fruit), vegetables (tomatoes, cucumbers, eggplants), and flowers.

[0003] Fertilizers suitable for use in irrigation systems must be water-soluble, and can be divided into three categories: water-soluble liquid fertilizers, water-soluble powder fertilizers, and water-soluble granular fertilizers. Among these, water-soluble granular fertilizers offer advantages over water-soluble liquid fertilizers due to their ease of transportation and high nutrient content. However, water-soluble granular fertilizers face challenges in granulation and a trade-off between solubility and storage stability. Good solubility can lead to water absorption during storage, resulting in clumping and reduced fertilizer efficacy. Furthermore, since drip irrigation systems are prone to clogging, developing a water-soluble granular fertilizer suitable for drip irrigation systems that boasts high granulation yield, good stability, and prevents clogging is of great significance.

[0004] Chinese patent CN119118754A discloses a long-acting water-soluble alkali-regulating fertilizer and its preparation method. The raw materials for this fertilizer are preferably fully water-soluble, resulting in a fully water-soluble product with less than 0.2% water-insoluble matter (G4 standard). Urea phosphate is used as the main acidic substance, allowing the product to achieve a pH value below 3.5 after water dissolution, thus regulating hard water. The raw material ratio is optimized, and a certain amount of ammonium sulfate and powdered industrial monoammonium phosphate are used, while controlling the urea ratio and the use of ammonium bicarbonate after drying. This reduces system moisture, stabilizes system humidity control, and solves the problem of deliquescence caused by material acidity during production. However, the yield of this technical solution is less than 80%.

[0005] Chinese patent CN119798006A discloses an organic-inorganic water-soluble fertilizer, its preparation method, and its application. It is made from the following raw materials in the indicated weight ratios: 0%–65% nitrogen source, 0%–70% phosphorus source, 0%–70% potassium source, 10%–15% organic matter, and 0.35%–3% trace elements. The organic-inorganic water-soluble fertilizer prepared by this technology has good water solubility and can be used for drip irrigation, sprinkler irrigation, fertigation, broadcasting, hole application, and furrow application. It can improve soil aggregate structure, loosen the soil, promote root development, increase the utilization rate of nitrogen, phosphorus, and trace elements, and improve the quality of agricultural products. However, this technology does not address the yield of the granulated product. Summary of the Invention

[0006] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the object of the present invention is to provide a water-soluble granular fertilizer suitable for drip irrigation systems and a method for preparing the same.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] On the one hand, the present invention provides a water-soluble granular fertilizer suitable for drip irrigation systems, comprising the following raw materials in parts by weight: 20-40 parts nitrogen fertilizer, 15-30 parts phosphate fertilizer, 20-40 parts potassium fertilizer, 10-20 parts organic matter, 0.5-1 part soybean polypeptide, 1-4 parts binder, and 2-5 parts anti-sticking agent.

[0009] The adhesive comprises isomaltitol, dopamine hydrochloride, and water;

[0010] The anti-sticking agent comprises rhamnolipid, acidic polysaccharide, polyethylene glycol-polycaprolactone copolymer, and water.

[0011] This invention uses nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, organic matter, and soybean polypeptides as active ingredients, providing rich and diverse nutrition to meet the needs of crops at different growth stages and promote root development and nutrient absorption. In existing technologies, polyvinyl alcohol is often used as a binder in the granulation process of water-soluble granular fertilizers. However, complete dissolution of polyvinyl alcohol generally requires heating to 65-75℃, which is not conducive to the rapid dissolution of water-soluble granular fertilizers. During experiments, this invention discovered that using an aqueous solution of isomaltitol and dopamine hydrochloride as a binder, leveraging the low hygroscopicity of isomaltitol and the viscosity and surface activity of dopamine hydrochloride, the combined use of isomaltitol and dopamine hydrochloride not only uniformly coats the surface of the granular fertilizer during granulation, effectively improving the yield of granular fertilizer, but also reduces physical adhesion between granules, lowering the agglomeration rate; and reduces the surface tension of the aqueous solution, increasing the dissolution rate.

[0012] Although the adhesive of this invention can reduce the caking rate of granular fertilizers to some extent, the majority of the components of water-soluble granular fertilizers are soluble salts, which are very easy to absorb moisture and form crystals, making them particularly prone to agglomeration and clumping, thus failing to meet the requirements for long-term storage of granular fertilizers. Traditional solutions typically use oil-based anti-caking agents, but based on the requirement that water-soluble granular fertilizers used in drip irrigation systems be fully soluble and not produce impurities that clog drip irrigation equipment, oil-based anti-caking agents cannot meet the requirements. Therefore, through experimental research, the inventors discovered that using rhamnose lipolipids, acidic polysaccharides, and polyethylene glycol-polycaprolactone copolymers as effective anti-caking agents can not only significantly reduce the caking rate of granular fertilizers but also improve the dissolution rate.

[0013] The inventors also discovered two key details. First, when the acidic polysaccharide is a soybean-soluble polysaccharide, the granular fertilizer prepared from it has a lower caking rate and a shorter dissolution time compared to that prepared from alginate. This is likely because soybean-soluble polysaccharides more readily form hydrogen bond networks with soybean peptides in the system of this invention, creating a more uniform liquid film on the surface of the fertilizer granules and firmly fixing them to the surface, thus preventing granular fertilizer adhesion. Alginate, on the other hand, has stronger viscosity, is more hygroscopic, and dissolves more slowly. Second, the mass ratio of rhamnolipin, acidic polysaccharide, polyethylene glycol-polycaprolactone copolymer, and water in the anti-adhesion agent also affects the caking rate and dissolution rate of the granular fertilizer. The optimal effect is achieved when the mass ratio of rhamnolipin, acidic polysaccharide, polyethylene glycol-polycaprolactone copolymer, and water is 2-5:1-3:5-8:100.

[0014] In this invention, the nitrogen fertilizer is a range of any one point or any two points from 30, 32, 34, 36, 38, 40, 42, 44, 46, 48 or 50 parts by weight.

[0015] In some preferred embodiments, the nitrogen fertilizer is selected from at least one of urea, ammonium sulfate, and ammonium bicarbonate.

[0016] More preferably, the nitrogen fertilizer is urea.

[0017] More preferably, the total nitrogen content of the urea is ≥46%.

[0018] In this invention, the weight parts of the phosphate fertilizer are any one value or a range of any two values ​​from 20 parts, 22 parts, 24 parts, 25 parts, 26 parts, 28 parts or 30 parts.

[0019] In some preferred embodiments, the phosphate fertilizer is selected from at least one of monoammonium phosphate and sodium dihydrogen phosphate.

[0020] More preferably, the phosphate fertilizer is monoammonium phosphate.

[0021] More preferably, the monoammonium phosphate is industrial grade monoammonium phosphate 12-61-0 (N:P:K).

[0022] In this invention, the weight parts of the potassium fertilizer are any one value or a range of any two values ​​selected from 25 parts, 26 parts, 28 parts, 30 parts, 32 parts, or 35 parts.

[0023] In some preferred embodiments, the potassium fertilizer is selected from at least one of potassium chloride, potassium sulfate, potassium nitrate, and potassium dihydrogen phosphate.

[0024] More preferably, the potassium fertilizer is potassium chloride.

[0025] More preferably, the potassium chloride contains 62% potassium oxide.

[0026] In this invention, the weight parts of the organic matter are any one value or a range of any two values ​​selected from 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, or 20 parts.

[0027] In some preferred embodiments, the organic matter is selected from at least one of water-soluble humic acid, seaweed extract, polyglutamic acid, and molasses.

[0028] More preferably, the organic matter is polyglutamic acid.

[0029] In this invention, the soybean polypeptide is a range of any one point or any two points from 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts or 1 part by weight.

[0030] In this invention, the weight parts of the adhesive are any one value or a range of any two values ​​from 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts or 4 parts.

[0031] In some preferred embodiments, the mass ratio of isomaltitol, dopamine hydrochloride, and water is 2-5:3-8:100.

[0032] More preferably, the mass ratio of isomaltitol, dopamine hydrochloride and water is 3:5:100.

[0033] In this invention, the weight parts of the anti-sticking agent are any one value or a range of any two values ​​selected from 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, or 5 parts.

[0034] In some preferred embodiments, the acidic polysaccharide is selected from at least one of alginate and soybean soluble polysaccharide.

[0035] More preferably, the acidic polysaccharide is a soybean soluble polysaccharide.

[0036] In some preferred embodiments, the mass ratio of rhamnolipid, acidic polysaccharide, polyethylene glycol-polycaprolactone copolymer and water is 2-5:1-3:5-8:100.

[0037] Preferably, the mass ratio of rhamnolipid, acidic polysaccharide, polyethylene glycol-polycaprolactone copolymer and water is 3:2:6:100.

[0038] On the other hand, the present invention provides a method for preparing a water-soluble granular fertilizer suitable for drip irrigation systems, comprising the following steps:

[0039] (1) Dissolve isomaltitol and dopamine hydrochloride in water to prepare an adhesive for later use; dissolve rhamnolipid, acidic polysaccharide and polyethylene glycol-polycaprolactone copolymer in water to prepare an anti-sticking agent for later use;

[0040] (2) Nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, organic matter and soybean polypeptide are crushed, and binder is added for granulation. After granulation, the fertilizer and anti-sticking agent are mixed evenly and dried to obtain water-soluble granular fertilizer.

[0041] More preferably, the granulated fertilizer has a particle size of 1-3 mm.

[0042] More preferably, step (2) of the method for preparing water-soluble granular fertilizer suitable for drip irrigation system is as follows: nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, organic matter and soybean polypeptide are placed in a crusher and mixer for crushing for 10-30 minutes, binder is added, and the mixture is stirred for 8-15 minutes. Then, the mixture is granulated in a rotary drum granulator to prepare granular fertilizer with a size of 1-3 mm. After granulation, the fertilizer and anti-sticking agent are mixed evenly and dried to obtain water-soluble granular fertilizer.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. This invention uses an aqueous solution of isomaltitol and dopamine hydrochloride as a binder, which effectively improves the yield of granular fertilizer, reduces the caking rate, and increases the dissolution rate.

[0045] 2. This invention uses rhamnolipin, acidic polysaccharide and polyethylene glycol-polycaprolactone copolymer as the effective components of the anti-sticking agent, and controls the mass ratio of rhamnolipin, acidic polysaccharide, polyethylene glycol-polycaprolactone copolymer and water to be 2-5:1-3:5-8:100, which can not only significantly reduce the clumping rate of granular fertilizer, but also improve the dissolution rate. Attached Figure Description

[0046] Figure 1 A photograph showing the appearance of the water-soluble granular fertilizer prepared in Example 1 of this invention;

[0047] Figure 2This is a photograph showing the appearance of the water-soluble granular fertilizer prepared in Comparative Example 1 of this invention.

[0048] Figure 3 The image shows the appearance of the water-soluble granular fertilizer prepared in Example 1 of this invention after being placed in an environment of 30°C and 75% relative humidity for 30 days.

[0049] Figure 4 The image shows the appearance of the water-soluble granular fertilizer prepared in Comparative Example 4 of this invention after being placed in an environment of 30°C and 75% relative humidity for 30 days.

[0050] Figure 5 The image shows the solubility appearance of the water-soluble granular fertilizer prepared in Example 1 of this invention after being placed in 200 mL (25°C) of water for 3 minutes.

[0051] Figure 6 The image shows the solubility appearance of the water-soluble granular fertilizer prepared in Comparative Example 1 of this invention after being placed in 200 mL (25°C) of water for 3 minutes.

[0052] Figure 7 The image shows the solubility appearance of the water-soluble granular fertilizer prepared in Comparative Example 2 of this invention after being placed in 200 mL (25°C) of water for 3 minutes.

[0053] Figure 8 This is a photograph showing the solubility of the water-soluble granular fertilizer prepared in Comparative Example 6 of this invention after being placed in 200 mL (25°C) of water for 3 minutes. Detailed Implementation

[0054] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific implementation schemes are now described in detail.

[0055] The present invention will be further described below with reference to embodiments, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0056] Unless otherwise specified, all raw materials used in the following examples and comparative examples are commercially available or prepared by conventional methods in the art.

[0057] The following are some exemplary sources of raw materials, but not limited to those shown:

[0058] Soybean peptides (molecular weight 150-1500 Da), purchased from Rushan Hualong Biotechnology Co., Ltd., model: FPD700.

[0059] Polyglutamic acid (molecular weight 150 W Da), purchased from Wuhan Juzhen Biotechnology Co., Ltd., model: 20% polyglutamic acid.

[0060] Soluble polysaccharides from soybeans were purchased from Jiangsu Caiwei Biotechnology Co., Ltd.

[0061] The polyethylene glycol-polycaprolactone copolymer (polyethylene glycol molecular weight 1K, polycaprolactone molecular weight 2000) was purchased from Guangzhou Weihua Biotechnology Co., Ltd.

[0062] Rhamnose lipolipase was purchased from Shaanxi Deguan Biotechnology Co., Ltd., product name: Shulide. ® RL-P 2225.

[0063] Isomaltitol (CAS: 64519-82-0).

[0064] Dopamine hydrochloride (CAS: 62-31-7).

[0065] Example 1

[0066] This embodiment provides a water-soluble granular fertilizer suitable for drip irrigation systems and its preparation method:

[0067] The water-soluble granular fertilizer suitable for drip irrigation systems is made from the following raw materials in parts by weight: 28 parts nitrogen fertilizer, 26.3 parts phosphate fertilizer, 25.8 parts potassium fertilizer, 12 parts organic matter, 0.9 parts soybean polypeptide, 3 parts binder, and 4 parts anti-sticking agent.

[0068] The nitrogen fertilizer is urea, and the total nitrogen content of the urea is 46%.

[0069] The phosphate fertilizer is monoammonium phosphate, and the monoammonium phosphate is industrial grade monoammonium phosphate 12-61-0 (N:P:K).

[0070] The potassium fertilizer is potassium chloride, and the potassium chloride contains 62% potassium oxide.

[0071] The organic matter is polyglutamic acid.

[0072] The adhesive is isomaltitol, dopamine hydrochloride and water in a mass ratio of 3:5:100;

[0073] The anti-sticking agent is composed of rhamnolipin, acidic polysaccharide, polyethylene glycol-polycaprolactone copolymer and water in a mass ratio of 3:2:6:100.

[0074] The acidic polysaccharide is a soybean-soluble polysaccharide.

[0075] The method for preparing the water-soluble granular fertilizer suitable for drip irrigation systems is as follows:

[0076] (1) Dissolve isomaltitol and dopamine hydrochloride in water to prepare an adhesive for later use; dissolve rhamnolipid, acidic polysaccharide and polyethylene glycol-polycaprolactone copolymer in water to prepare an anti-sticking agent for later use;

[0077] (2) Nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, organic matter and soybean polypeptide are placed in a crusher and mixer for crushing for 30 minutes, binder is added and stirred for 12 minutes, and then granulated in a rotary drum granulator to prepare granular fertilizer with a size of 1-3 mm. After granulation, the fertilizer and anti-sticking agent are mixed evenly and dried to obtain water-soluble granular fertilizer.

[0078] The appearance of the obtained water-soluble granular fertilizer is as follows: Figure 1 As shown, the products of other embodiments and comparative examples are similar to... Figure 1 resemblance.

[0079] The appearance of the obtained water-soluble granular fertilizer after 30 days in an environment of 30℃ and 75% relative humidity is shown in the following photos. Figure 3 As shown, the products of other embodiments are similar to Figure 3 resemblance.

[0080] The appearance of the obtained water-soluble granular fertilizer after being placed in 200 mL (25℃) of water for 3 minutes is shown in the image. Figure 5 As shown, the products of other embodiments are similar to Figure 5 resemblance.

[0081] Example 2

[0082] This embodiment provides a water-soluble granular fertilizer suitable for drip irrigation systems and its preparation method:

[0083] The water-soluble granular fertilizer suitable for drip irrigation systems is made from the following raw materials in parts by weight: 28.3 parts nitrogen fertilizer, 16.4 parts phosphate fertilizer, 32.3 parts potassium fertilizer, 13.3 parts organic matter, 0.7 parts soybean polypeptide, 4 parts binder, and 5 parts anti-sticking agent.

[0084] The nitrogen fertilizer is urea, and the total nitrogen content of the urea is 46%.

[0085] The phosphate fertilizer is monoammonium phosphate, and the monoammonium phosphate is industrial grade monoammonium phosphate 12-61-0 (N:P:K).

[0086] The potassium fertilizer is potassium chloride, and the potassium chloride contains 62% potassium oxide.

[0087] The organic matter is polyglutamic acid.

[0088] The adhesive is isomaltitol, dopamine hydrochloride and water in a mass ratio of 3:5:100;

[0089] The anti-sticking agent is composed of rhamnolipin, acidic polysaccharide, polyethylene glycol-polycaprolactone copolymer and water in a mass ratio of 3:2:6:100.

[0090] The acidic polysaccharide is a soybean-soluble polysaccharide.

[0091] The method for preparing the water-soluble granular fertilizer suitable for drip irrigation systems is as follows:

[0092] (1) Dissolve isomaltitol and dopamine hydrochloride in water to prepare an adhesive for later use; dissolve rhamnolipid, acidic polysaccharide and polyethylene glycol-polycaprolactone copolymer in water to prepare an anti-sticking agent for later use;

[0093] (2) Nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, organic matter and soybean polypeptide are placed in a crusher and mixer for crushing for 30 minutes, binder is added and stirred for 12 minutes, and then granulated in a rotary drum granulator to prepare granular fertilizer with a size of 1-3 mm. After granulation, the fertilizer and anti-sticking agent are mixed evenly and dried to obtain water-soluble granular fertilizer.

[0094] Example 3

[0095] This embodiment provides a water-soluble granular fertilizer suitable for drip irrigation systems and its preparation method:

[0096] The water-soluble granular fertilizer suitable for drip irrigation systems is made from the following raw materials in parts by weight: 21.8 parts nitrogen fertilizer, 16.4 parts phosphate fertilizer, 38.7 parts potassium fertilizer, 14.1 parts organic matter, 1 part soybean polypeptide, 4.5 parts binder, and 3.5 parts anti-sticking agent.

[0097] The nitrogen fertilizer is urea, and the total nitrogen content of the urea is 46%.

[0098] The phosphate fertilizer is monoammonium phosphate, and the monoammonium phosphate is industrial grade monoammonium phosphate 12-61-0 (N:P:K).

[0099] The potassium fertilizer is potassium chloride, and the potassium chloride contains 62% potassium oxide.

[0100] The organic matter is polyglutamic acid.

[0101] The adhesive is isomaltitol, dopamine hydrochloride and water in a mass ratio of 3:5:100;

[0102] The anti-sticking agent is composed of rhamnolipin, acidic polysaccharide, polyethylene glycol-polycaprolactone copolymer and water in a mass ratio of 3:2:6:100.

[0103] The acidic polysaccharide is a soybean-soluble polysaccharide.

[0104] The method for preparing the water-soluble granular fertilizer suitable for drip irrigation systems is as follows:

[0105] (1) Dissolve isomaltitol and dopamine hydrochloride in water to prepare an adhesive for later use; dissolve rhamnolipid, acidic polysaccharide and polyethylene glycol-polycaprolactone copolymer in water to prepare an anti-sticking agent for later use;

[0106] (2) Nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, organic matter and soybean polypeptide are placed in a crusher and mixer for crushing for 30 minutes, binder is added and stirred for 12 minutes, and then granulated in a rotary drum granulator to prepare granular fertilizer with a size of 1-3 mm. After granulation, the fertilizer and anti-sticking agent are mixed evenly and dried to obtain water-soluble granular fertilizer.

[0107] Example 4

[0108] This embodiment provides a water-soluble granular fertilizer suitable for drip irrigation systems and its preparation method:

[0109] The water-soluble granular fertilizer suitable for drip irrigation systems is made from the following raw materials in parts by weight: 28 parts nitrogen fertilizer, 26.3 parts phosphate fertilizer, 25.8 parts potassium fertilizer, 12 parts organic matter, 0.9 parts soybean polypeptide, 3 parts binder, and 4 parts anti-sticking agent.

[0110] The nitrogen fertilizer is urea, and the total nitrogen content of the urea is 46%.

[0111] The phosphate fertilizer is monoammonium phosphate, and the monoammonium phosphate is industrial grade monoammonium phosphate 12-61-0 (N:P:K).

[0112] The potassium fertilizer is potassium chloride, and the potassium chloride contains 62% potassium oxide.

[0113] The organic matter is polyglutamic acid.

[0114] The adhesive is isomaltitol, dopamine hydrochloride and water in a mass ratio of 3:5:100;

[0115] The anti-sticking agent is composed of rhamnolipin, acidic polysaccharide, polyethylene glycol-polycaprolactone copolymer and water in a mass ratio of 3:2:6:100.

[0116] The acidic polysaccharide is an alginate.

[0117] The method for preparing the water-soluble granular fertilizer suitable for drip irrigation systems is as follows:

[0118] (1) Dissolve isomaltitol and dopamine hydrochloride in water to prepare an adhesive for later use; dissolve rhamnolipid, acidic polysaccharide and polyethylene glycol-polycaprolactone copolymer in water to prepare an anti-sticking agent for later use;

[0119] (2) Nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, organic matter and soybean polypeptide are placed in a crusher and mixer for crushing for 30 minutes, binder is added and stirred for 12 minutes, and then granulated in a rotary drum granulator to prepare granular fertilizer with a size of 1-3 mm. After granulation, the fertilizer and anti-sticking agent are mixed evenly and dried to obtain water-soluble granular fertilizer.

[0120] Comparative Example 1

[0121] This comparative example provides a water-soluble granular fertilizer suitable for drip irrigation systems and its preparation method; the only difference from Example 1 is that isomalt is replaced with an equal mass of sorbitol; all other aspects are the same.

[0122] The appearance of the obtained water-soluble granular fertilizer is shown in the following photos. Figure 2 As shown, the uniformity of the formed granules is relatively poor. Comparative Example 2 shows the appearance of the water-soluble granular fertilizer. Figure 2 resemblance.

[0123] The obtained water-soluble granular fertilizer was placed in 200 mL (25℃) of water for 3 minutes. The solubility appearance of the fertilizer is shown in the following image. Figure 6 As shown, it cannot be completely dissolved.

[0124] Comparative Example 2

[0125] This comparative example provides a water-soluble granular fertilizer suitable for drip irrigation systems and its preparation method; the only difference from Example 1 is that dopamine hydrochloride is replaced with an equal mass of polyvinyl alcohol; all other aspects are the same.

[0126] The obtained water-soluble granular fertilizer was placed in 200 mL (25℃) of water for 3 minutes. The solubility appearance of the fertilizer is shown in the following image. Figure 7 As shown, it cannot be completely dissolved.

[0127] Comparative Example 3

[0128] This comparative example provides a water-soluble granular fertilizer suitable for drip irrigation systems and its preparation method; the only difference from Example 1 is that rhamnolipid is replaced with an equal mass of propylene glycol monostearate; all other aspects are the same.

[0129] Comparative Example 4

[0130] This comparative example provides a water-soluble granular fertilizer suitable for drip irrigation systems and its preparation method; the only difference from Example 1 is that the polyethylene glycol-polycaprolactone copolymer is replaced with an equal mass of acidic polysaccharide, that is, the mass ratio of rhamnolipid, acidic polysaccharide and water is 3:8:100; all other aspects are the same.

[0131] The appearance of the obtained water-soluble granular fertilizer after 30 days in an environment of 30℃ and 75% relative humidity is shown in the following photos. Figure 4As shown, the products of other comparative examples and Figure 4 Similarly, both exhibit a relatively high degree of clumping.

[0132] Comparative Example 5

[0133] This comparative example provides a water-soluble granular fertilizer suitable for drip irrigation systems and its preparation method; the only difference from Example 1 is that the acidic polysaccharide is replaced with an equal mass of polyethylene glycol-polycaprolactone copolymer, that is, the mass ratio of the rhamnolipid, polyethylene glycol-polycaprolactone copolymer and water is 3:8:100; all other aspects are the same.

[0134] Comparative Example 6

[0135] This comparative example provides a water-soluble granular fertilizer suitable for drip irrigation systems and its preparation method; the only difference from Example 1 is that the anti-sticking agent is rhamnolipin, acidic polysaccharide, polyethylene glycol-polycaprolactone copolymer and water in a mass ratio of 6:1:4:100.

[0136] The obtained water-soluble granular fertilizer was placed in 200 mL (25℃) of water for 3 minutes. The solubility appearance of the fertilizer is shown in the following image. Figure 8 As shown, it cannot be completely dissolved; other comparative products and Figure 8 Similarly, it cannot be completely dissolved within 3 minutes.

[0137] Experimental example: The water-soluble granular fertilizers prepared in the examples and comparative examples were tested for relevant indicators, including fertilizer granule yield, accelerated agglomeration test and dissolution time.

[0138] The yield of fertilizer granules = mass of unbroken fertilizer granules / total weight of raw materials input × 100%.

[0139] The accelerated agglomeration experiment: Water-soluble granular fertilizer was placed in an environment of 30℃ and 75% relative humidity for 30 days, and the agglomeration rate was calculated: Agglomeration rate = mass of agglomerated fertilizer granules / total mass of fertilizer granules × 100%.

[0140] Dissolution time: Place 5g of water-soluble granular fertilizer in 200mL (25℃) of water and observe the time it takes for it to completely dissolve.

[0141] The test results are shown in Table 1 below:

[0142] Table 1

[0143] Test Project Yield / % clumping rate / % Dissolution time / min Example 1 92.5 8.3 2.2 Example 2 90.1 9.7 2.5 Example 3 91.8 11.2 3.1 Example 4 91.9 12.5 2.8 Comparative Example 1 84.2 18.4 4.3 Comparative Example 2 78.9 22.6 5.8 Comparative Example 3 91.8 25.1 6.2 Comparative Example 4 92.9 28.7 7.5 Comparative Example 5 92.1 20.9 5.1 Comparative Example 6 92.3 26.5 8.2

[0144] As can be seen from Table 1:

[0145] The fertilizer granules prepared in Examples 1-4 have a yield of more than 85%, an agglomeration rate of less than 15%, and a dissolution time of less than 4 minutes.

[0146] The changes in the composition of the binder in Comparative Examples 1 and 2 not only led to a decrease in the yield of fertilizer granules, but also significantly affected the agglomeration rate and had a certain impact on the dissolution rate.

[0147] The changes in the composition of the anti-sticking agent in Comparative Examples 3-5 and the ratio of the anti-sticking agent in Comparative Example 6 not only led to an increase in the caking rate of granular fertilizer, but also significantly affected the dissolution rate.

[0148] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A water-soluble granular fertilizer suitable for drip irrigation systems, characterized in that, The raw materials include the following parts by weight: 20-40 parts nitrogen fertilizer, 15-30 parts phosphate fertilizer, 20-40 parts potassium fertilizer, 10-20 parts organic matter, 0.5-1 part soybean polypeptide, 1-4 parts binder, and 2-5 parts anti-sticking agent. The adhesive comprises isomaltitol, dopamine hydrochloride, and water; The anti-sticking agent comprises rhamnose lipolipid, acidic polysaccharide, polyethylene glycol-polycaprolactone copolymer, and water; The acidic polysaccharide is selected from at least one of alginate and soybean soluble polysaccharide; The mass ratio of rhamnolipin, acidic polysaccharide, polyethylene glycol-polycaprolactone copolymer and water is 2-5:1-3:5-8:

100.

2. The water-soluble granular fertilizer suitable for drip irrigation systems according to claim 1, characterized in that, The mass ratio of isomaltitol, dopamine hydrochloride, and water is 2-5:3-8:

100.

3. The water-soluble granular fertilizer suitable for drip irrigation systems according to claim 2, characterized in that, The acidic polysaccharide is a soybean-soluble polysaccharide.

4. The water-soluble granular fertilizer suitable for drip irrigation systems according to claim 3, characterized in that, The mass ratio of rhamnolipid, acidic polysaccharide, polyethylene glycol-polycaprolactone copolymer and water is 3:2:6:

100.

5. The water-soluble granular fertilizer suitable for drip irrigation systems according to claim 4, characterized in that, The nitrogen fertilizer is selected from at least one of urea, ammonium sulfate, and ammonium bicarbonate; the phosphate fertilizer is selected from at least one of monoammonium phosphate and sodium dihydrogen phosphate; and the potassium fertilizer is selected from at least one of potassium chloride, potassium sulfate, potassium nitrate, and potassium dihydrogen phosphate.

6. The water-soluble granular fertilizer suitable for drip irrigation systems according to claim 5, characterized in that, The organic matter is selected from at least one of water-soluble humic acid, seaweed extract, polyglutamic acid, and molasses.

7. The water-soluble granular fertilizer suitable for drip irrigation systems according to claim 6, characterized in that, The organic matter is polyglutamic acid.

8. The method for preparing the water-soluble granular fertilizer suitable for drip irrigation systems according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Dissolve isomaltitol and dopamine hydrochloride in water to prepare an adhesive for later use; dissolve rhamnolipid, acidic polysaccharide and polyethylene glycol-polycaprolactone copolymer in water to prepare an anti-sticking agent for later use; (2) Nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, organic matter and soybean polypeptide are crushed, and binder is added for granulation. After granulation, the fertilizer and anti-sticking agent are mixed evenly and dried to obtain water-soluble granular fertilizer.

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