Slow-release composite organic liquid water-soluble fertilizer based on natural extracts and preparation method of slow-release composite organic liquid water-soluble fertilizer

Abstract

The invention discloses a slow-release composite organic liquid water-soluble fertilizer based on natural extracts and a preparation method thereof, and belongs to the technical field of agricultural fertilizers. The preparation method comprises the following steps: mixing a cross-linked mussel mucoprotein mixed solution, a diamine cross-linking agent and an oxidized cyclodextrin-vegetable oil-urea inclusion mixed solution according to a weight part ratio of 1: (0.01-0.02): (3-5), then controlling the temperature to be 30-35 DEG C, and stirring and reacting for 2-3 hours to obtain the slow-release composite organic liquid water-soluble fertilizer. The preparation method comprises the following steps: firstly, constructing a high-temperature-resistant cross-linked mussel mucoprotein mixed solution through condensation cross-linking, then wrapping urea to obtain an oxidized cyclodextrin-vegetable oil-urea inclusion mixed solution by utilizing the characteristic that cyclodextrin is externally hydrophilic and an internal cavity is hydrophobic, and finally, preparing a high-temperature-resistant cross-linked mussel mucoprotein film by virtue of a diamine cross-linking agent. And cross-linking the oxidized cyclodextrin-vegetable oil-urea inclusion mixed solution and the cross-linked mussel mucin mixed solution through amino and aldehyde groups to form the slow-release composite organic liquid water-soluble fertilizer.

Description

Technical Field

[0001] The present invention belongs to the technical field of agricultural fertilizers, and particularly relates to a slow-release composite organic liquid water-soluble fertilizer based on natural extracts and a preparation method thereof. Background Art

[0002] The growth of the world's population has increased the demand for food. To meet the current food supply, a large area of fertile land is needed to grow more food. However, factors such as industrialization, soil degradation, and urbanization have reduced agricultural land. At the same time, due to insufficient nutrient supply, a large amount of fertilizer is required to grow food on barren farmland. Although the role of fertilizers in increasing crop yields is undeniable, excessive input can have a great negative impact on the environment such as groundwater and the atmosphere. Since the fertilizers applied to the soil cannot be absorbed and utilized in time, a large amount of nutrient elements in the fertilizers easily flow into groundwater and surface water through surface runoff and farmland drainage, causing eutrophication of water bodies such as lakes and rivers. The main reason for the low fertilizer efficiency is the unreasonable fertilization structure. Crops need different nutrients for growth, and blind application of fertilizers will only increase production costs and environmental pollution. With the increase in food production, fertilizers are still an indispensable production factor in crop production. Therefore, in the process of increasing food production, how to improve fertilizer utilization efficiency in agricultural production, while reducing the pollution of fertilizers to the soil and the environment, and realizing the green ecological sustainable development of agriculture is an important guarantee for the sustainable development of agriculture. In this context, slow-release fertilizers have emerged as the times require. Slow-release fertilizers are based on chemical fertilizers and regulate and control the release of nutrients through various methods to improve the absorption rate of plants for nutrients. Due to the persistence of nutrient release, slow-release water-soluble fertilizers can reduce the frequency of fertilization, thereby effectively reducing nutrient loss, reducing the risk of water eutrophication, and reducing the occurrence of environmental problems such as soil salinization. Moreover, the components of slow-release fertilizers can improve soil structure, promote the activity of soil microorganisms, enhance the water retention capacity and aeration of the soil, thereby improving the soil health level. From the current situation of slow-release fertilizers, the slow-release fertilizers currently on the market include urea formaldehyde coating, sulfur-coated urea, and polystyrene-coated urea. Although these slow-release fertilizers have achieved slow-release performance to a certain extent, due to the certain pollution of the polymer materials used to the environment, the popularization of slow-release fertilizers is relatively difficult. Therefore, it is of great significance to develop bio-friendly slow-release fertilizers and reduce environmental pollution.

[0003] Patent CN116730771A discloses a slow-release nitrogen fertilizer and its preparation method. This invention introduces a MOF-COF composite material, which has high stability in aqueous solution. The MOF-COF composite material contains high-density nitrogen-containing groups and oxygen-containing groups, and the lone pair electrons on nitrogen are beneficial to improving the adsorption performance. At the same time, sodium carboxymethylcellulose and sodium alginate are also introduced to form a slow-release nitrogen fertilizer with a multi-porous structure with the MOF-COF composite material, which has good water retention and fertilizer retention capabilities while improving the slow-release performance, effectively improving crop productivity and not polluting the environment.

[0004] Patent CN116283420A discloses a preparation method of a composite slow-release nitrogen fertilizer for improving the bait supply capacity of shellfish farming. In this invention, a block prepared from ammonium chloride, gelatinized starch, sodium alginate and water is impregnated in a calcium chloride solution, and through the gelation reaction between sodium alginate and calcium chloride, the easily soluble nitrogen fertilizer is air-dried through a pressing and impregnation process to obtain a composite slow-release nitrogen fertilizer.

[0005] Biologically sourced materials have natural environmental protection advantages. Mussels are a kind of marine organism, and the mussel adhesive protein contained in them is a bio-based environmental protection material with good application prospects and excellent adhesion performance. However, due to the low content of mussel adhesive protein in mussels, the adhesion of the directly extracted mussel adhesive protein is poor. Therefore, at present, most mussel adhesive proteins are prepared by gene recombination, and the cost of preparing mussel adhesive protein by gene recombination technology is high, and it is difficult to promote and apply. Moreover, the waterproof performance of mussel adhesive protein is high after adhesion, and the hydrophilicity is poor. When directly applied to fertilizers, it has a great impact on the water retention performance of fertilizers and is not conducive to the fertilizers to play their roles.

[0006] Therefore, modifying the mussel adhesive protein directly extracted from mussels to make it have good adhesion and water retention performance is of great significance for improving the utilization efficiency of fertilizers and reducing the use of polymer macromolecular materials in slow-release fertilizers. Summary of the Invention

[0007] In view of the deficiencies of the prior art, the present invention first constructs a crosslinked mussel adhesive protein mixture with high temperature resistance through condensation crosslinking, then utilizes the characteristics of the outer hydrophilic and inner cavity hydrophobic of cyclodextrin to wrap urea to obtain an oxidized cyclodextrin-vegetable oil-urea inclusion mixture, and finally uses a diamine crosslinking agent to crosslink the oxidized cyclodextrin-vegetable oil-urea inclusion mixture and the crosslinked mussel adhesive protein mixture through amino and aldehyde groups to form a slow-release composite organic liquid water-soluble fertilizer, solving the technical problems proposed in the background art. Specifically, the technical solution of the present invention includes the following contents:

[0008] One of the purposes of the present invention is to provide a preparation method of a slow-release composite organic liquid water-soluble fertilizer based on natural extracts, and the preparation method includes the following steps:

[0009] The crosslinked mussel adhesive protein mixture, diamine crosslinking agent, and oxidized cyclodextrin-vegetable oil-urea inclusion complex mixture are mixed in a weight ratio of 1:0.01 - 0.02:3 - 5, and then stirred and reacted at a temperature of 30°C - 35°C for 2h - 3h to obtain the slow-release composite organic liquid water-soluble fertilizer.

[0010] Furthermore, the preparation method of the crosslinked mussel adhesive protein mixture includes the following steps:

[0011] Mussel minced meat and distilled water are mixed at a material-liquid ratio of 1:1 - 2 and then subjected to high-speed homogenization to obtain mussel meat slurry;

[0012] After adjusting the pH of the mussel meat slurry to 7 - 7.5, neutral protease is added, and the temperature is controlled at 45°C - 50°C for enzymatic hydrolysis for 3h - 5h to obtain an enzymatic hydrolysate;

[0013] The enzymatic hydrolysate and dialdehyde crosslinking agent are mixed and reacted at 20°C - 25°C for 10h - 12h, and then subjected to high-temperature inactivation treatment at 80°C - 90°C for 10min - 15min to obtain the crosslinked mussel adhesive protein mixture.

[0014] Furthermore, the conditions for the high-speed homogenization include a rotation speed of 8000r / min - 10000r / min and a treatment time of 90s - 150s.

[0015] Furthermore, the addition amount of the neutral protease is 0.6% - 0.7% of the weight of the mussel meat slurry.

[0016] Furthermore, the dialdehyde crosslinking agent includes glyoxal.

[0017] Furthermore, the weight ratio of the enzymatic hydrolysate to the dialdehyde crosslinking agent is 1:0.005 - 0.007.

[0018] Furthermore, the diamine crosslinking agent includes ethylenediamine or 1,3-propanediamine.

[0019] Furthermore, the preparation method of the oxidized cyclodextrin-vegetable oil-urea inclusion complex mixture includes the following steps:

[0020] Urea and vegetable oil are mixed at a weight ratio of 1:2 - 4 and then subjected to high-speed shearing to obtain a dispersion, and the dispersion and emulsifier are mixed and stirred at a weight ratio of 1:0.01 - 0.02 to obtain a vegetable oil-coated urea mixture;

[0021] The oxidized cyclodextrin solution and the vegetable oil-coated urea mixture are mixed at a weight ratio of 1 - 5:1 and then mixed and stirred in a temperature environment of 25°C - 30°C for 2h - 4h to obtain the oxidized cyclodextrin-vegetable oil-urea inclusion complex mixture.

[0022] Furthermore, the vegetable oil includes soybean oil or peanut oil.

[0023] Furthermore, the conditions for high-speed shearing include a rotation speed of 5000 r / min to 6000 r / min and a shearing time of 3 min to 4 min.

[0024] Furthermore, the emulsifier includes Span 60 or Span 80.

[0025] Furthermore, the method for preparing the oxidized cyclodextrin solution includes the following steps:

[0026] After cyclodextrin is added to water and dissolved and dispersed, sodium periodate is mixed with the dissolved cyclodextrin according to the weight ratio of cyclodextrin:sodium periodate of 1:1 to obtain a reaction solution. After adjusting the pH of the reaction solution to 5.0 - 6.0, the reaction is carried out at 20°C - 25°C for 1 h - 1.5 h to obtain the oxidized cyclodextrin solution.

[0027] Furthermore, the cyclodextrin includes β-cyclodextrin or γ-cyclodextrin.

[0028] The second object of the present invention is to provide a slow-release composite organic liquid water-soluble fertilizer prepared by the method for preparing a slow-release composite organic liquid water-soluble fertilizer based on natural extracts.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] The present invention enzymatically hydrolyzes mussels to obtain an enzymatic hydrolysate containing mussel adhesive protein. Then, according to the characteristic that the mussel adhesive protein contains amino groups in its structure, a dialdehyde crosslinking agent containing a dialdehyde functional group is mixed with the enzymatic hydrolysate for reaction. Through the condensation crosslinking between amino groups and aldehyde groups, dynamic imine bonds with high-temperature resistance are formed. Since the enzymatic hydrolysate contains neutral protease required for enzymatic hydrolysis, high-temperature inactivation treatment is needed to remove the neutral protease to prevent further enzymatic hydrolysis from damaging the adhesiveness of mussel adhesive protein. The content of mussel adhesive protein in natural mussels is relatively low. If it is not protected, the mussel adhesive protein is prone to denaturation and loss of adhesiveness activity during high-temperature inactivation. Therefore, the dialdehyde crosslinking agent containing a dialdehyde functional group can provide high-temperature protection for it through high-temperature-resistant dynamic imine bonds, reducing the loss of the activity of mussel adhesive protein, and then obtaining a crosslinked mussel adhesive protein mixture. Then, through high-speed shearing, vegetable oil is used to wrap urea, thereby forming a vegetable oil-encapsulated urea mixture with hydrophobic properties. Utilizing the characteristic that the outer surface of cyclodextrin is hydrophilic while the inner cavity is hydrophobic, the vicinal diol structure on the surface of cyclodextrin is first oxidized to obtain an aqueous solution of oxidized cyclodextrin containing aldehyde functional groups. Then, the vegetable oil-encapsulated urea mixture and the oxidized cyclodextrin solution are mixed and stirred, so that the hydrophobic vegetable oil-encapsulated urea mixture is encapsulated into the hydrophobic cavity inside the oxidized cyclodextrin, obtaining an oxidized cyclodextrin-vegetable oil-urea inclusion mixture. Finally, with the aid of a diamine crosslinking agent, the oxidized cyclodextrin-vegetable oil-urea inclusion mixture and the crosslinked mussel adhesive protein mixture are crosslinked through amino groups and aldehyde groups to form a slow-release composite organic liquid water-soluble fertilizer. This crosslinking treatment has the following advantages: On the one hand, when preparing the crosslinked mussel adhesive protein mixture, in order to reduce the adhesiveness activity of mussel adhesive protein in the enzymatic hydrolysate caused by high-temperature inactivation, a dialdehyde crosslinking agent is used to construct a high-temperature-resistant system. However, due to the crosslinking of amino groups and aldehyde groups in mussel adhesive protein, the adhesiveness of mussel adhesive protein, which is already weak due to its low content, further decreases. At this time, with the aid of a diamine crosslinking agent, the overall adhesiveness performance can be improved, so that when the fertilizer is applied to the soil, it can adhere well to the soil and will not be lost too quickly. On the other hand, the outer surface of oxidized cyclodextrin contains a large number of hydrophilic groups. After crosslinking, it can improve the hydrophilic performance of mussel adhesive protein. As a result, the finally prepared slow-release composite organic liquid water-soluble fertilizer has good water retention performance after being applied to the soil, improving the utilization efficiency of the fertilizer. Detailed implementation manners

[0031] The technical solutions of the present invention will be clearly and completely described below through the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0032] Unless otherwise specified, the raw materials and reagents used in the following invention are all commercially available products or can be prepared by known methods.

[0033] Preparation Example 1

[0034] A method for preparing a cross-linked mussel adhesive protein mixture specifically includes the following process:

[0035] Wash the surface impurities of the commercially purchased fresh mussels with tap water, then remove the shells to obtain mussel meat. Cut the mussel meat into small pieces with scissors to get mussel minced meat. According to the material-liquid ratio, mix 1 part by weight of mussel minced meat and 1 part by weight of distilled water, and then put it into a homogenizer. Adjust the rotation speed to 8000 r / min and perform homogenization treatment for 90 s to obtain mussel meat slurry. Adjust the pH value of the mussel meat slurry to 7 with ammonia water, then use a pipette to add 0.6% of neutral protease based on the weight of the mussel meat slurry to it for mixing, and then place it in an environment at a temperature of 45°C and time the enzymatic hydrolysis for 3 h. After the enzymatic hydrolysis is completed, take out the obtained enzymatic hydrolysate, and then add glyoxal cross-linking agent to the enzymatic hydrolysate according to 0.005 times the weight of the enzymatic hydrolysate for mixing and control the mixing temperature at 20°C. Set the mixing rotation speed to 200 r / min and stir and mix for 10 h. After the mixing reaction is completed, immediately place it in a temperature environment of 80°C for high-temperature inactivation treatment, and maintain the treatment time for 10 min. After inactivation, naturally cool to room temperature to obtain a cross-linked mussel adhesive protein mixture, and then place it in a temperature environment of 5°C for low-temperature storage for later use.

[0036] Preparation Example 2

[0037] A method for preparing a cross-linked mussel adhesive protein mixture specifically includes the following process:

[0038] Wash the surface impurities of the commercially purchased fresh mussels with tap water, then remove the shells to obtain mussel meat. Cut the mussel meat into small pieces with scissors to get mussel minced meat. According to the material-liquid ratio, mix 1 part by weight of mussel minced meat and 1.5 parts by weight of distilled water, and then put it into a homogenizer. Adjust the rotation speed to 9000 r / min and perform homogenization treatment for 120 s to obtain mussel meat slurry. Adjust the pH value of the mussel meat slurry to 7.5 with ammonia water, then use a pipette to add 0.65% of neutral protease based on the weight of the mussel meat slurry to it for mixing, and then place it in an environment at a temperature of 45°C and time the enzymatic hydrolysis for 4 h. After the enzymatic hydrolysis is completed, take out the obtained enzymatic hydrolysate, and then add glyoxal cross-linking agent to the enzymatic hydrolysate according to 0.006 times the weight of the enzymatic hydrolysate for mixing and control the mixing temperature at 25°C. Set the mixing rotation speed to 200 r / min and stir and mix for 11 h. After the mixing reaction is completed, immediately place it in a temperature environment of 85°C for high-temperature inactivation treatment, and maintain the treatment time for 12 min. After inactivation, naturally cool to room temperature to obtain a cross-linked mussel adhesive protein mixture, and then place it in a temperature environment of 5°C for low-temperature storage for later use.

[0039] Preparation Example 3

[0040] A method for preparing a crosslinked mussel adhesive protein mixture, specifically including the following process:

[0041] Wash the surface impurities of commercially purchased fresh mussels with tap water, then remove the shells and take out the mussel meat. Cut the mussel meat into small pieces with scissors to obtain mussel minced meat. According to the material-liquid ratio, mix 1 part by weight of mussel minced meat and 2 parts by weight of distilled water, and then put it into a homogenizer. Adjust the rotation speed to 10,000 r / min and perform homogenization treatment for 150 s to obtain mussel meat slurry. Adjust the pH value of the mussel meat slurry to 7.5 with ammonia water, then use a pipette to add 0.7% of neutral protease based on the weight of the mussel meat slurry into it for mixing, and then place it in an environment with a temperature of 50 °C and time the enzymatic hydrolysis for 5 h. After the enzymatic hydrolysis is completed, take out the obtained enzymatic hydrolysate, and then add glyoxal crosslinking agent to the enzymatic hydrolysate according to 0.007 times the weight of the enzymatic hydrolysate for mixing and control the mixing temperature at 25 °C. Set the mixing rotation speed to 200 r / min and stir and mix for 12 h. After the mixing reaction is completed, immediately place it in a temperature environment of 90 °C for high-temperature inactivation treatment, and maintain the treatment time for 15 min. After inactivation, naturally cool to room temperature to obtain a crosslinked mussel adhesive protein mixture, and then place it in a temperature environment of 5 °C for low-temperature storage for later use.

[0042] Preparation Example 4

[0043] A method for preparing a crosslinked mussel adhesive protein mixture, specifically including the following process:

[0044] Wash the surface impurities of commercially purchased fresh mussels with tap water, then remove the shells and take out the mussel meat. Cut the mussel meat into small pieces with scissors to obtain mussel minced meat. According to the material-liquid ratio, mix 1 part by weight of mussel minced meat and 2 parts by weight of distilled water, and then put it into a homogenizer. Adjust the rotation speed to 10,000 r / min and perform homogenization treatment for 150 s to obtain mussel meat slurry. Adjust the pH value of the mussel meat slurry to 7.5 with ammonia water, then use a pipette to add 0.7% of neutral protease based on the weight of the mussel meat slurry into it for mixing, and then place it in an environment with a temperature of 50 °C and time the enzymatic hydrolysis for 5 h. After the enzymatic hydrolysis is completed, take out the obtained enzymatic hydrolysate and place it in a temperature environment of 90 °C for high-temperature inactivation treatment, and maintain the treatment time for 15 min. After inactivation, naturally cool to room temperature to obtain a crosslinked mussel adhesive protein mixture, and then place it in a temperature environment of 5 °C for low-temperature storage for later use.

[0045] Preparation Example 5

[0046] A method for preparing a crosslinked mussel adhesive protein mixture, specifically including the following process:

[0047] Replace the glyoxal crosslinking agent in Preparation Example 3 with a glutaraldehyde crosslinking agent, and keep the other conditions the same as those in Preparation Example 3.

[0048] Preparation Example 6

[0049] The preparation method of the oxidized cyclodextrin solution specifically includes the following process:

[0050] Add β-cyclodextrin to water, stir to dissolve and disperse evenly (heating can be appropriately carried out to promote dissolution), then add sodium periodate with the same weight part as β-cyclodextrin to form a mixed reaction solution, adjust the pH of the reaction solution to 5.0 with dilute hydrochloric acid, then carry out light-shielding treatment in a temperature environment of 20°C, then time the reaction for 1 h. After the reaction is completed, carry out dialysis treatment with a 500 Da dialysis bag to obtain the oxidized cyclodextrin solution.

[0051] Preparation Example 7

[0052] The preparation method of the oxidized cyclodextrin solution specifically includes the following process:

[0053] Add β-cyclodextrin to water, stir to dissolve and disperse evenly (heating can be appropriately carried out to promote dissolution), then add sodium periodate with the same weight part as β-cyclodextrin to form a mixed reaction solution, adjust the pH of the reaction solution to 5.5 with dilute hydrochloric acid, then carry out light-shielding treatment in a temperature environment of 20°C, then time the reaction for 70 min. After the reaction is completed, carry out dialysis treatment with a 500 Da dialysis bag to obtain the oxidized cyclodextrin solution.

[0054] Preparation Example 8

[0055] The preparation method of the oxidized cyclodextrin solution specifically includes the following process:

[0056] Add γ-cyclodextrin to water, stir to dissolve and disperse evenly (heating can be appropriately carried out to promote dissolution), then add sodium periodate with the same weight part as γ-cyclodextrin to form a mixed reaction solution, adjust the pH of the reaction solution to 6.0 with dilute hydrochloric acid, then carry out light-shielding treatment in a temperature environment of 25°C, then time the reaction for 1.5 h. After the reaction is completed, carry out dialysis treatment with a 500 Da dialysis bag to obtain the oxidized cyclodextrin solution.

[0057] Preparation Example 9

[0058] The preparation method of the oxidized cyclodextrin solution specifically includes the following process:

[0059] Add α-cyclodextrin to water, stir to dissolve and disperse evenly (heating can be appropriately carried out to promote dissolution), then add sodium periodate in an equal weight portion to α-cyclodextrin to form a mixed reaction solution, adjust the pH of the reaction solution to 6.0 with dilute hydrochloric acid, then carry out light-shielding treatment in a temperature environment of 25 °C, and then time the reaction for 1.5 h. After the reaction is completed, carry out dialysis treatment with a 500 Da dialysis bag to obtain an oxidized cyclodextrin solution.

[0060] Preparation Example 10

[0061] A method for preparing an oxidized cyclodextrin solution specifically includes the following process:

[0062] Add γ-cyclodextrin to water, stir to dissolve and disperse evenly (heating can be appropriately carried out to promote dissolution), then add sodium periodate in an equal weight portion to γ-cyclodextrin to form a mixed reaction solution, adjust the pH of the reaction solution to 4.0 with dilute hydrochloric acid, then carry out light-shielding treatment in a temperature environment of 30 °C, and then time the reaction for 2 h. After the reaction is completed, carry out dialysis treatment with a 500 Da dialysis bag to obtain an oxidized cyclodextrin solution.

[0063] Preparation Example 11

[0064] A method for preparing an oxidized cyclodextrin-vegetable oil-urea inclusion mixture specifically includes the following process:

[0065] Weigh 1 part by weight of urea and 2 parts by weight of soybean oil and mix them together, then put them into a high-speed shearer, control the shear speed at 5000 r / min, and carry out shear treatment for 3 min. After the shear treatment is completed, take out the obtained dispersion, add Span 60 to the dispersion according to 0.01 times the weight of the dispersion, and stir at a speed of 300 r / min for 20 min to obtain a vegetable oil-coated urea mixture. Weigh 1 part by weight of the oxidized cyclodextrin solution prepared in Preparation Example 6 and 1 part by weight of the vegetable oil-coated urea mixture and mix them, and then control the mixing and stirring at 25 °C for 2 h to obtain an oxidized cyclodextrin-vegetable oil-urea inclusion mixture.

[0066] Preparation Example 12

[0067] A method for preparing an oxidized cyclodextrin-vegetable oil-urea inclusion mixture specifically includes the following process:

[0068] Weigh 1 part by weight of urea and 3 parts by weight of soybean oil, mix them together, then put them into a high-speed shearer, control the shear speed at 5500 r / min, and conduct shear treatment for 3 min. After the shear treatment is completed, take out the obtained dispersion, add Span 60 to the dispersion according to 0.015 times the weight of the dispersion, and mix them, then stir at a speed of 300 r / min for 20 min to obtain a urea mixture wrapped in vegetable oil. Weigh 3 parts by weight of the oxidized cyclodextrin solution prepared in Preparation Example 7 and 1 part by weight of the urea mixture wrapped in vegetable oil, mix them, and then control the mixing and stirring at a temperature of 30 °C for 3 h to obtain an oxidized cyclodextrin-vegetable oil-urea inclusion complex mixture solution.

[0069] Preparation Example 13

[0070] A method for preparing an oxidized cyclodextrin-vegetable oil-urea inclusion complex mixture solution specifically includes the following process:

[0071] Weigh 1 part by weight of urea and 4 parts by weight of peanut oil, mix them together, then put them into a high-speed shearer, control the shear speed at 6000 r / min, and conduct shear treatment for 4 min. After the shear treatment is completed, take out the obtained dispersion, add Span 80 to the dispersion according to 0.02 times the weight of the dispersion, and mix them, then stir at a speed of 300 r / min for 20 min to obtain a urea mixture wrapped in vegetable oil. Weigh 5 parts by weight of the oxidized cyclodextrin solution prepared in Preparation Example 8 and 1 part by weight of the urea mixture wrapped in vegetable oil, mix them, and then control the mixing and stirring at a temperature of 30 °C for 4 h to obtain an oxidized cyclodextrin-vegetable oil-urea inclusion complex mixture solution.

[0072] Preparation Example 14

[0073] A method for preparing an oxidized cyclodextrin-vegetable oil-urea inclusion complex mixture solution specifically includes the following process:

[0074] Replace the oxidized cyclodextrin solution in Preparation Example 13 with the oxidized cyclodextrin solution obtained in Preparation Example 9, and keep the other conditions the same as those in Preparation Example 13.

[0075] Preparation Example 15

[0076] A method for preparing an oxidized cyclodextrin-vegetable oil-urea inclusion complex mixture solution specifically includes the following process:

[0077] Replace the oxidized cyclodextrin solution in Preparation Example 13 with the oxidized cyclodextrin solution obtained in Preparation Example 10, and keep the other conditions the same as those in Preparation Example 13.

[0078] Preparation Example 16

[0079] A method for preparing an oxidized cyclodextrin-vegetable oil-urea inclusion complex mixture solution specifically includes the following process:

[0080] Weigh 1 part by weight of urea and 4 parts by weight of peanut oil, mix them together, and then put them into a high-speed shearer. Control the shear speed at 7000 r / min and perform shear treatment for 5 min. After the shear treatment is completed, take out the obtained dispersion. According to 0.02 times the weight of the dispersion, add Span 80 to the dispersion and mix. Stir at a speed of 300 r / min for 20 min to obtain a vegetable oil-coated urea mixture. Weigh 5 parts by weight of the oxidized cyclodextrin solution prepared in Preparation Example 8 and 1 part by weight of the vegetable oil-coated urea mixture, mix them, and then control the mixing in a temperature environment of 30 °C and stir for 4 h to obtain an oxidized cyclodextrin-vegetable oil-urea inclusion mixture solution.

[0081] Example 1

[0082] A preparation method of a slow-release composite organic liquid water-soluble fertilizer based on natural extracts specifically includes the following process:

[0083] Mix 1 part by weight of the crosslinked mussel mucin mixture solution obtained in Preparation Example 1, 0.01 part by weight of an ethylenediamine crosslinking agent, and 3 parts by weight of the oxidized cyclodextrin-vegetable oil-urea inclusion mixture solution obtained in Preparation Example 11. Then control the mixing temperature at 30 °C and stir and react at a speed of 200 r / min for 2 h to obtain a slow-release composite organic liquid water-soluble fertilizer.

[0084] Example 2

[0085] A preparation method of a slow-release composite organic liquid water-soluble fertilizer based on natural extracts specifically includes the following process:

[0086] Mix 1 part by weight of the crosslinked mussel mucin mixture solution obtained in Preparation Example 2, 0.015 part by weight of an ethylenediamine crosslinking agent, and 4 parts by weight of the oxidized cyclodextrin-vegetable oil-urea inclusion mixture solution obtained in Preparation Example 12. Then control the mixing temperature at 30 °C and stir and react at a speed of 200 r / min for 2.5 h to obtain a slow-release composite organic liquid water-soluble fertilizer.

[0087] Example 3

[0088] A preparation method of a slow-release composite organic liquid water-soluble fertilizer based on natural extracts specifically includes the following process:

[0089] Mix 1 part by weight of the crosslinked mussel mucin mixture solution obtained in Preparation Example 3, 0.02 part by weight of a 1,3-propanediamine crosslinking agent, and 5 parts by weight of the oxidized cyclodextrin-vegetable oil-urea inclusion mixture solution obtained in Preparation Example 13. Then control the mixing temperature at 35 °C and stir and react at a speed of 200 r / min for 3 h to obtain a slow-release composite organic liquid water-soluble fertilizer.

[0090] Comparative Example 1

[0091] A preparation method of a slow-release composite organic liquid water-soluble fertilizer based on natural extracts, specifically including the following process:

[0092] Replace the cross-linked mussel mucin mixture in Example 3 with the cross-linked mussel mucin mixture obtained in Preparation Example 4, and keep the remaining conditions the same as those in Example 3.

[0093] Comparative Example 2

[0094] A preparation method of a slow-release composite organic liquid water-soluble fertilizer based on natural extracts, specifically including the following process:

[0095] Replace the cross-linked mussel mucin mixture in Example 3 with the cross-linked mussel mucin mixture obtained in Preparation Example 5, and keep the remaining conditions the same as those in Example 3.

[0096] Comparative Example 3

[0097] A preparation method of a slow-release composite organic liquid water-soluble fertilizer based on natural extracts, specifically including the following process:

[0098] Replace the oxidized cyclodextrin-vegetable oil-urea inclusion mixture in Example 3 with the oxidized cyclodextrin-vegetable oil-urea inclusion mixture obtained in Preparation Example 14, and keep the remaining conditions the same as those in Example 3.

[0099] Comparative Example 4

[0100] A preparation method of a slow-release composite organic liquid water-soluble fertilizer based on natural extracts, specifically including the following process:

[0101] Replace the oxidized cyclodextrin-vegetable oil-urea inclusion mixture in Example 3 with the oxidized cyclodextrin-vegetable oil-urea inclusion mixture obtained in Preparation Example 15, and keep the remaining conditions the same as those in Example 3.

[0102] Comparative Example 5

[0103] A preparation method of a slow-release composite organic liquid water-soluble fertilizer based on natural extracts, specifically including the following process:

[0104] Replace the oxidized cyclodextrin-vegetable oil-urea inclusion mixture in Example 3 with the oxidized cyclodextrin-vegetable oil-urea inclusion mixture obtained in Preparation Example 16, and keep the remaining conditions the same as those in Example 3.

[0105] Comparative Example 6

[0106] A preparation method of a slow-release composite organic liquid water-soluble fertilizer based on natural extracts, specifically including the following process:

[0107] Mix 1 part by weight of the crosslinked mussel adhesive protein mixture obtained in Preparation Example 3, 0.02 part by weight of 1,3-propanediamine crosslinking agent, and 5 parts by weight of the oxidized cyclodextrin-vegetable oil-urea inclusion complex mixture obtained in Preparation Example 13. Then, control the mixing temperature at 35 °C and stir and react at a speed of 200 r / min for 10 h. It is found that the fertilizer gel solidifies.

[0108] According to the standard of "GB / T 23348-2009 Slow-release Fertilizers", mix the slow-release compound organic liquid water-soluble fertilizers prepared in Examples 1 to 3 and Comparative Examples 1 to 5 with tap water 500 times their own weight and place them in an environment of 25 ± 2 °C. Detect the cumulative release rate of the dissolved urea on the 28th day. The results are shown in Table 1 below.

[0109] Table 1 Cumulative release rate of urea

[0110]

[0111]

[0112] Mix the slow-release compound organic liquid water-soluble fertilizers prepared in Examples 1 to 3 and Comparative Examples 1 to 6 with tap water 500 times their own weight. Weigh 9 plastic boxes containing 500 g of dry soil respectively, pierce 20 small holes at the bottom of the plastic boxes, pour the above water-soluble fertilizers into the plastic boxes containing dry soil. Wait until water flows out from the pinholes at the bottom of the plastic box and stops flowing, then seal the plastic box with a plastic film, only expose the pinholes at the bottom, place a plastic cup directly below the pinholes at the bottom to catch water, then place it in a constant temperature incubator at 25 ± 2 °C to observe the water leakage situation, and weigh the weight of the water in the plastic cup on the 3rd day. The results are shown in Table 2 below.

[0113] Table 2 Water retention test

[0114]

[0115]

[0116] The following conclusions can be drawn from Table 1 and Table 2 above:

[0117] (1) It can be found from Examples 1 to 3 that the present invention first constructs a crosslinked mussel adhesive protein mixture with high temperature resistance through condensation crosslinking, then utilizes the characteristics that the outside of cyclodextrin is hydrophilic and the inner cavity is hydrophobic to encapsulate urea to obtain an oxidized cyclodextrin-vegetable oil-urea inclusion complex mixture, and finally with the help of a diamine crosslinking agent, crosslink the oxidized cyclodextrin-vegetable oil-urea inclusion complex mixture and the crosslinked mussel adhesive protein mixture through amino and aldehyde groups to form a slow-release compound organic liquid water-soluble fertilizer, which has good slow-release and water retention properties.

[0118] (2) It can be found from Comparative Example 1 that since the mussel adhesive protein contained in mussels is relatively low, if no cross-linking protection treatment is carried out, it may lead to the weakening of the activity of mussel adhesive protein in the enzymolysis solution during high-temperature inactivation, and without cross-linking protection, when mixed with the oxidized cyclodextrin-vegetable oil-urea inclusion complex mixture later, although the amino groups contained in the mussel adhesive protein itself can be cross-linked with the oxidized cyclodextrin-vegetable oil-urea inclusion complex mixture through a diamine cross-linking agent, the adhesion is poor, resulting in poor water retention performance of the finally prepared slow-release composite organic liquid water-soluble fertilizer.

[0119] (3) It can be found from Comparative Example 2 that although glutaraldehyde also contains two aldehyde groups and can be cross-linked, due to the relatively long carbon chain of glutaraldehyde, when it is introduced into the cross-linked mussel adhesive protein mixture, the relatively long carbon chain will increase the hydrophobicity to a certain extent, resulting in poor water retention performance of the finally prepared slow-release composite organic liquid water-soluble fertilizer.

[0120] (4) It can be found from Comparative Example 3 that although α-cyclodextrin has the same hydrophilic outer and hydrophobic inner cavity structure, it may be due to the relatively large particle size of the vegetable oil-encapsulated urea mixture obtained by encapsulating urea with vegetable oil, resulting in poor encapsulation effect of α-cyclodextrin on the vegetable oil-encapsulated urea mixture, making the finally prepared slow-release composite organic liquid water-soluble fertilizer release faster.

[0121] (5) It can be found from Comparative Example 4 that further increasing the acidic environment, reaction temperature and reaction time, although it is beneficial for sodium periodate to further oxidize the vicinal diol structure to generate aldehyde groups, but in this system, due to excessive oxidation, the cavity structure of γ-cyclodextrin may be damaged, unable to achieve the encapsulation of urea, and then resulting in the loss of the slow-release effect of the prepared slow-release composite organic liquid water-soluble fertilizer.

[0122] (6) It can be found from Comparative Example 5 that due to excessive high-speed shearing treatment, the encapsulation of peanut oil on urea may be damaged, and urea is water-soluble, making the prepared slow-release composite organic liquid water-soluble fertilizer lose its slow-release effect.

[0123] (7) It can be found from Comparative Example 6 that due to too long cross-linking time, gel solidification phenomenon occurs, and it is difficult to dissolve in the room temperature test environment (25 ± 2 °C) after adding water, and the amount of urea dissolved is extremely low, resulting in the failure of preparation.

[0124] The above embodiments have described in detail the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A method for preparing a slow-release composite organic liquid water-soluble fertilizer based on natural extracts, characterized in that: The preparation method comprises the following steps: The cross-linked mussel mucin mixed liquid, the diamine cross-linking agent and the oxidized cyclodextrin-vegetable oil-urea inclusion mixed liquid are mixed in a weight ratio of 1:0.01-0.02:3-5, and then the temperature is controlled at 30°C-35°C and stirred for reaction for 2h-3h to obtain the slow-release composite organic liquid water-soluble fertilizer.

2. The method for preparing a slow-release composite organic liquid water-soluble fertilizer based on natural extracts according to claim 1, characterized in that: The preparation method of the cross-linked mussel mucin mixed solution comprises the following steps: The minced mussel meat and distilled water are mixed in a solid-liquid ratio of 1:1-2 and then subjected to high-speed homogenization to obtain a mussel meat slurry; After the pH of the mussel meat slurry is adjusted to 7-7.5, a neutral protease is added, and the temperature is controlled at 45° C.-50° C. for enzymolysis for 3 h-5 h to obtain an enzymolysis solution; The enzymatic hydrolysate and the dialdehyde cross-linking agent are mixed and reacted at 20°C to 25°C for 10h to 12h, and then subjected to high temperature inactivation treatment at 80°C to 90°C for 10min to 15min to obtain the cross-linked mussel mucin mixed solution.

3. The method for preparing a slow-release composite organic liquid water-soluble fertilizer based on natural extracts according to claim 2, characterized in that: The dialdehyde-based cross-linking agent includes glyoxal.

4. The method for preparing a slow-release composite organic liquid water-soluble fertilizer based on natural extracts according to claim 2, characterized in that: The weight ratio of the enzymatic hydrolysate to the dialdehyde cross-linking agent is 1:0.005-0.

007.

5. The method for preparing a slow-release composite organic liquid water-soluble fertilizer based on natural extracts according to claim 1, characterized in that: The diamine crosslinking agent includes ethylenediamine or 1,3-propylenediamine.

6. The method for preparing a slow-release composite organic liquid water-soluble fertilizer based on natural extracts according to claim 1, characterized in that: The preparation method of the oxidized cyclodextrin-vegetable oil-urea inclusion mixed solution comprises the following steps: Urea and vegetable oil are mixed in a weight ratio of 1:2-4 and subjected to high-speed shearing to obtain a dispersion, and the dispersion and emulsifier are mixed and stirred in a weight ratio of 1:0.01-0.02 to obtain a vegetable oil-coated urea mixture; The oxidized cyclodextrin solution and the vegetable oil-encapsulated urea mixture are mixed in a weight ratio of 1 to 5:1, and then stirred in a temperature environment of 25° C. to 30° C. for 2 h to 4 h to obtain the oxidized cyclodextrin-vegetable oil-urea inclusion body mixture.

7. The method for preparing a slow-release composite organic liquid water-soluble fertilizer based on natural extracts according to claim 6, characterized in that: The vegetable oil includes soybean oil or peanut oil.

8. The method for preparing a slow-release composite organic liquid water-soluble fertilizer based on natural extracts according to claim 6, characterized in that: The preparation method of the oxidized cyclodextrin solution comprises the following steps: After cyclodextrin is dissolved and dispersed in water, sodium periodate is mixed with the dissolved cyclodextrin in a weight ratio of cyclodextrin to sodium periodate of 1:1 to obtain a reaction solution. After adjusting the pH of the reaction solution to 5.0-6.0, the reaction solution is reacted at 20° C.-25° C. in the dark for 1 h-1.5 h to obtain the oxidized cyclodextrin solution.

9. A slow-release composite organic liquid water-soluble fertilizer prepared by the method for preparing a slow-release composite organic liquid water-soluble fertilizer based on natural extracts according to any one of claims 1 to 8.

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