Selenium-rich water-soluble compound fertilizer and preparation method thereof

Abstract

The invention relates to the technical field of compound fertilizers, in particular to a selenium-rich water-soluble compound fertilizer. The selenium-rich water-soluble compound fertilizer comprises the following components in parts by weight: 10-15 parts of selenium sustained-release microspheres, 8-12 parts of a natural compound extract, 1-2 parts of potassium chloride, 1-3 parts of monoammonium phosphate, 0.1-0.2 part of EDTA chelated zinc, 0.05-0.08 part of borax and 300-500 parts of deionized water, and the selenium-rich water-soluble compound fertilizer prepared by the invention can slowly release selenium elements and effectively improve the selenium content of plants.

Description

Technical Field

[0001] The invention relates to the technical field of compound fertilizers, and in particular to a selenium-rich water-soluble compound fertilizer and a preparation method thereof. Background Art

[0002] Selenium is an essential trace element for maintaining human health. Since the human body cannot synthesize the required organic selenium, it is necessary to maintain the selenium level in the body through dietary intake. Biological selenium enrichment is an effective way to obtain organic selenium. Ingesting selenium-rich fruits and vegetables and other foods is the most important way for the human body to obtain organic selenium. However, the content of selenium in natural fruits and vegetables is relatively low, and most of them need to apply selenium fertilizers to strengthen the crops to produce selenium-rich agricultural products. At present, most selenium fertilizers are made by adding selenite or selenium-rich ore to ordinary fertilizers. Although the cost is low and the operation is simple, there are some defects. Selenate and selenite are inherently toxic. If they are not applied properly, they are easy to pollute the soil; due to the complex composition of selenium-rich ores, the selenium in the ores is not easy for plants to absorb and utilize, and the biological effectiveness is low. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a selenium-rich water-soluble compound fertilizer and a preparation method thereof.

[0004] The present invention is achieved through the following technical solutions: A selenium-rich water-soluble compound fertilizer comprises the following components in parts by weight: 10-15 parts of selenium slow-release microspheres, 8-12 parts of natural compound extracts, 1-2 parts of potassium chloride, 1-3 parts of monoammonium phosphate, 0.1-0.2 parts of EDTA chelated zinc, 0.05-0.08 parts of borax, and 300-500 parts of deionized water.

[0005] Furthermore, the raw materials for preparing the selenium sustained-release microspheres include the following components in parts by weight: 4-6 parts of rosmarinic acid, 2-3 parts of xylitol, 2-3 parts of itaconic acid, 6-9 parts of N-(hydroxymethyl)acrylamide, 25-35 parts of acrylamide, 6-8 parts of sodium selenite, 4-6 parts of fulvic acid, 6-8 parts of sodium alginate, 30-40 parts of polyvinyl alcohol, and 15-20 parts of dopamine hydrochloride.

[0006] Furthermore, the preparation method of the selenium sustained-release microspheres comprises the following steps: (1) Add rosmarinic acid and xylitol to N,N-dimethylformamide and mix well, add DMAP and DCC, stir at 70-80°C and 150-200 rpm for 4-5 h, cool to room temperature, centrifuge at 8000 rpm for 15-20 min, wash the precipitate with deionized water, and dry under vacuum at 60-70°C to obtain modified rosmarinic acid; (2) Under N2 protection, Span 60 and cyclohexane were mixed, and stirred at 40°C and 300-400 rpm for 40-50 min to obtain an organic phase, and acrylamide, modified rosmarinic acid, itaconic acid, N-(hydroxymethyl)acrylamide and ammonium persulfate were dissolved in distilled water to obtain an aqueous phase; (3) The aqueous phase obtained in step (2) is added slowly and continuously to the organic phase. After the addition is completed, the mixture is stirred at 60-70° C. and 100-150 rpm for 4-5 h, cooled to room temperature, centrifuged at 5000 rpm for 15-20 min, the precipitate is washed with anhydrous ethanol and deionized water, vacuum dried at 30° C., added to 10 times the weight of distilled water, rapidly frozen with liquid nitrogen, and freeze-dried at -60° C. for 24-28 h to obtain porous modified polyacrylamide microspheres; (4) dissolving sodium selenite in deionized water to obtain a sodium selenite solution, mixing the porous modified polyacrylamide microspheres obtained in step (3) with the sodium selenite solution, ultrasonicating at 300-400 W for 40-50 min, filtering, and vacuum drying to obtain selenium-loaded microspheres; (5) adding fulvic acid, sodium alginate and polyvinyl alcohol to deionized water, stirring at 80-90° C. and 150-200 rpm for 30 min to obtain a mixed solution, adding the selenium-loaded microspheres obtained in step (4) to the mixed solution, stirring at 200-300 rpm for 1 h, adding dropwise to a boric acid solution of calcium chloride, stirring for 20-30 min, centrifuging at 5000 rpm for 20-30 min, washing the precipitate with deionized water, and vacuum drying to obtain gel sustained-release microspheres; (6) Dopamine hydrochloride is dissolved in 10 mM Tris-HCl buffer to obtain a dopamine solution with a concentration of 10 mg / mL, and the gel sustained-release microspheres obtained in step (5) are added to the dopamine solution, stirred at 200-300 rpm for 2-3 h, filtered, and the filter cake is washed with deionized water and freeze-dried at -40°C to obtain selenium sustained-release microspheres.

[0007] Furthermore, in step (1), the mass concentration of xylitol in N,N-dimethylformamide is 16-20 mg / mL.

[0008] Furthermore, in step (1), the mass ratio of xylitol, DCC and DMAP is 1:1.2:0.4.

[0009] Furthermore, in step (2), the mass ratio of Span 60 to cyclohexane in the organic phase is 1:300.

[0010] Furthermore, in step (2), the ratio of acrylamide to deionized water in the aqueous phase is 1 g: 25-35 mL.

[0011] Furthermore, in step (2), the amount of ammonium persulfate used is 10-15 wt % of acrylamide.

[0012] Furthermore, in step (3), the volume ratio of the aqueous phase to the organic phase is 1:3-4.

[0013] Furthermore, in step (4), the mass concentration of sodium selenite in deionized water is 10-16 mg / mL.

[0014] Furthermore, in step (5), the mass concentration of the polyvinyl alcohol in deionized water is 30-40 mg / mL.

[0015] Furthermore, in step (5), the mass concentration of calcium chloride in the boric acid solution of calcium chloride is 4-6wt%, and the mass concentration of boric acid is 3-4wt%.

[0016] Furthermore, the raw materials for preparing the natural composite extract include the following components in parts by weight: 5-7 parts of Hemiptera: 6-8 parts of Herba Lycopodii, 2-3 parts of Verbena, 8-12 parts of Ascophylla, 2-3 parts of Andrographis paniculata, and 4-6 parts of Eucheuma.

[0017] Furthermore, the method for preparing the natural composite extract comprises the following steps: (a) Wash and dry Hemiptera: Hemiptera: Hemiptera: Hemiptera: Hemiptera: Verbena: Ascophylla: Andrographis: Andrographis: Euphorbia: Euphorbia: Hemiptera ... -3 MPa to 20% of the original volume and freeze-dried at -40°C to obtain the natural water extract; (b) the filter residue obtained in step (a) was mixed evenly with 15 times the weight of deionized water, glucose and urea were added, and ultraviolet sterilization was performed to obtain a fermentation substrate, and the activated Bacillus inulinus was added at 10 7 cfu / mL was inoculated into the fermentation substrate, and the culture was carried out at 80-100 r / min and 30°C for 48 h, cooled to room temperature, centrifuged at 5000 rpm for 20-30 min, and the supernatant was freeze-dried at -40°C to obtain a natural fermentation extract; (c) uniformly mixing the natural water extract obtained in step (a) and the natural fermentation extract obtained in step (b) in a mass ratio of 1:2-3 to obtain a natural composite extract.

[0018] Furthermore, in step (b), the mass ratio of the filter residue, glucose and urea is 1:1.2-1.5:0.7-1.

[0019] Furthermore, in step (b), the Bacillus inulinus was purchased from China General Microbiological Culture Collection Center with a license number of CGMCC 1.3844.

[0020] Furthermore, the present invention also provides a method for preparing the selenium-rich water-soluble compound fertilizer, comprising the following steps: adding selenium slow-release microspheres, natural composite extracts, potassium chloride, monoammonium phosphate, EDTA chelated zinc and borax into deionized water, stirring at 40°C and 40-60 rpm for 1 h, and stirring at room temperature for 30 min to obtain the selenium-rich water-soluble compound fertilizer.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The invention provides a selenium-rich water-soluble compound fertilizer, and selenium slow-release microspheres are prepared, which can be effectively adsorbed on the surface of leaves, slow-release selenium elements, and are beneficial to plant absorption and utilization, and natural composite extracts are prepared, and natural components in plants are extracted, and water extraction and microbial fermentation extraction are performed, and effective components are fully utilized, synergistically enhancing the effect, and are beneficial to plant growth. The invention prepares selenium slow-release microspheres, and rosmarinic acid and xylitol are subjected to esterification reaction to prepare modified rosmarinic acid, and rosmarinic acid has multiple phenolic hydroxyl groups, can chelate effective components, and promote absorption and utilization, contains double bonds, and can participate in the polymerization of polyacrylamide, and the modified rosmarinic acid is introduced into polyacrylamide, and xylitol can chelate with sodium selenite, thereby increasing the amount of selenium, promoting the absorption of selenium elements by plants, and improving the absorption and utilization rate of selenium. Itaconic acid contains a double bond and can participate in the polymerization of polyacrylamide. Itaconic acid is introduced into polyacrylamide, and itaconic acid can provide an acidic environment, which is conducive to the absorption and utilization of selenium. The present invention polymerizes modified rosmarinic acid, itaconic acid, acrylamide and N-(hydroxymethyl) acrylamide to prepare modified polyacrylamide, prepares porous modified polyacrylamide microspheres by freezing, and loads sodium selenite by chelation and porous adsorption dual effects to obtain selenium-loaded microspheres. The present invention coats the selenium-loaded microspheres with fulvic acid, polyvinyl alcohol and sodium alginate materials, which can be cross-linked with each other under the action of boric acid and calcium chloride, and the selenium-loaded microspheres are wrapped to form a first coating layer, which is conducive to the sustained release of selenium, and then the dopamine self-polymerization reaction is used to wrap the polydopamine layer to form a second coating layer, which can improve dispersibility, is conducive to adsorption on plant leaves, and improves fertilizer efficiency. The invention prepares a natural composite extract, extracts Hemiptera: Hemiptera: Herba Lysimachiae, Herba Verbenae, Herba Verbenae, Herba Ascophyllae, Herba Andrographis and Herba Eucheuma by water to obtain a water extract, and ferments the filter residue by using Bacillus inulinus to obtain a fermentation extract. The fermentation by using Bacillus inulinus is beneficial to improving the fertilizer efficiency, synergizing the components and promoting the absorption and utilization by plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 The selenium-enriching effect of the selenium-enriched water-soluble compound fertilizers described in Examples 1-3 and Comparative Examples 1-4 of the present invention; Figure 2 This is the sustained-release effect of the selenium sustained-release microspheres described in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. It should be noted that, unless otherwise specified, the chemical reagents involved in the present invention are purchased through commercial channels.

[0025] Example 1: A selenium-rich water-soluble compound fertilizer comprises the following components in parts by weight: 15 parts of selenium slow-release microspheres, 12 parts of natural compound extracts, 2 parts of potassium chloride, 3 parts of monoammonium phosphate, 0.2 parts of EDTA chelated zinc, 0.08 parts of borax, and 500 parts of deionized water.

[0026] The raw materials for preparing selenium sustained-release microspheres include the following components in parts by weight: 6 parts of rosmarinic acid, 3 parts of xylitol, 3 parts of itaconic acid, 9 parts of N-(hydroxymethyl)acrylamide, 35 parts of acrylamide, 8 parts of sodium selenite, 6 parts of fulvic acid, 8 parts of sodium alginate, 40 parts of polyvinyl alcohol, and 20 parts of dopamine hydrochloride.

[0027] The preparation method of selenium sustained-release microspheres comprises the following steps: (1) 6 g of rosmarinic acid and 3 g of xylitol were added to 150 mL of N,N-dimethylformamide and mixed evenly. 1.2 g of DMAP and 3.6 g of DCC were added. The mixture was stirred at 80°C and 200 rpm for 5 h. The mixture was cooled to room temperature and centrifuged at 8000 rpm for 20 min. The precipitate was washed with deionized water and dried in a vacuum at 70°C to obtain modified rosmarinic acid. (2) Under N2 protection, Span 60 and cyclohexane were mixed in a mass ratio of 1:300, and stirred at 40°C and 400 rpm for 50 min to obtain an organic phase. 35 g of acrylamide, modified rosmarinic acid, 3 g of itaconic acid, 9 g of N-(hydroxymethyl)acrylamide, and 5.25 g of ammonium persulfate were dissolved in 1225 mL of distilled water to obtain an aqueous phase. (3) The aqueous phase obtained in step (2) was slowly added to the organic phase, with the volume ratio of the aqueous phase to the organic phase being 1:4. After the addition, the mixture was stirred at 70°C and 150 rpm for 5 h, cooled to room temperature, centrifuged at 5000 rpm for 20 min, the precipitate was washed with anhydrous ethanol and deionized water, vacuum dried at 30°C, added to 10 times the weight of distilled water, rapidly frozen with liquid nitrogen, and freeze-dried at -60°C for 28 h to obtain porous modified polyacrylamide microspheres; (4) dissolving 8 g of sodium selenite in 500 mL of deionized water to obtain a sodium selenite solution, mixing the porous modified polyacrylamide microspheres obtained in step (3) with the sodium selenite solution, ultrasonicating at 400 W for 50 min, filtering, and vacuum drying to obtain selenium-loaded microspheres; (5) Add 6 g of fulvic acid, 8 g of sodium alginate and 40 g of polyvinyl alcohol to 1000 mL of deionized water, stir at 90°C and 200 rpm for 30 min to obtain a mixed solution, add the selenium-loaded microspheres obtained in step (4) to the mixed solution, stir at 300 rpm for 1 h, add dropwise to a boric acid solution of calcium chloride, wherein the mass concentration of calcium chloride is 6 wt % and the mass concentration of boric acid is 4 wt %, stir for 30 min, centrifuge at 5000 rpm for 30 min, wash the precipitate with deionized water, and vacuum dry to obtain gel sustained-release microspheres; (6) Dissolve 20 g of dopamine hydrochloride in 2 L of 10 mM Tris-HCl buffer to obtain a dopamine solution with a concentration of 10 mg / mL, add the gel sustained-release microspheres obtained in step (5) to the dopamine solution, stir at 300 rpm for 3 h, filter, wash the filter cake with deionized water, and freeze-dry at -40°C to obtain selenium sustained-release microspheres.

[0028] The raw materials for preparing the natural composite extract include the following components in parts by weight: 7 parts of Hemiptera: ...

[0029] The preparation method of the natural composite extract comprises the following steps: (a) Wash and dry Hemiptera: Hemiptera: Hemiptera: Hemiptera: Hemiptera: Verbena: Ascophylla: Andrographis: Andrographis: Euphorbia: Euphorbia: Hemiptera ... -3 MPa to 20% of the original volume and freeze-dried at -40°C to obtain the natural water extract; (b) the filter residue obtained in step (a) was mixed evenly with 15 times the weight of deionized water, glucose and urea were added, the mass ratio of the filter residue, glucose and urea was 1:1.5:1, ultraviolet sterilization was performed to obtain a fermentation substrate, and the activated Bacillus inulinus was added at 107 cfu / mL was inoculated into the fermentation substrate, and the culture was carried out at 100 r / min and 30°C for 48 h, cooled to room temperature, centrifuged at 5000 rpm for 30 min, and the supernatant was freeze-dried at -40°C to obtain the natural fermentation extract; (c) mixing the natural water extract obtained in step (a) and the natural fermentation extract obtained in step (b) in a mass ratio of 1:3 to obtain a natural composite extract.

[0030] This embodiment also provides a preparation method of the selenium-rich water-soluble compound fertilizer, comprising the following steps: adding 15 g of selenium slow-release microspheres, 12 g of natural compound extract, 2 g of potassium chloride, 3 g of monoammonium phosphate, 0.2 g of EDTA chelated zinc and 0.08 g of borax into 500 g of deionized water, stirring at 40° C. and 60 rpm for 1 h, and stirring at room temperature for 30 min to obtain a selenium-rich water-soluble compound fertilizer.

[0031] Example 2: A selenium-rich water-soluble compound fertilizer comprises the following components in parts by weight: 10 parts of selenium slow-release microspheres, 8 parts of natural compound extracts, 1 part of potassium chloride, 1 part of monoammonium phosphate, 0.1 parts of EDTA chelated zinc, 0.05 parts of borax, and 300 parts of deionized water.

[0032] The raw materials for preparing selenium sustained-release microspheres include the following components in parts by weight: 4 parts of rosmarinic acid, 2 parts of xylitol, 2 parts of itaconic acid, 6 parts of N-(hydroxymethyl)acrylamide, 25 parts of acrylamide, 6 parts of sodium selenite, 4 parts of fulvic acid, 6 parts of sodium alginate, 30 parts of polyvinyl alcohol, and 15 parts of dopamine hydrochloride.

[0033] The preparation method of selenium sustained-release microspheres comprises the following steps: (1) 4 g of rosmarinic acid and 2 g of xylitol were added to 125 mL of N,N-dimethylformamide and mixed evenly. 0.8 g of DMAP and 2.4 g of DCC were added. The mixture was stirred at 70°C and 150 rpm for 4 h. The mixture was cooled to room temperature and centrifuged at 8000 rpm for 15 min. The precipitate was washed with deionized water and dried in a vacuum at 60°C to obtain modified rosmarinic acid. (2) Under N2 protection, Span 60 and cyclohexane were mixed in a mass ratio of 1:300, and stirred at 40°C and 300 rpm for 40 min to obtain an organic phase. 25 g of acrylamide, modified rosmarinic acid, 2 g of itaconic acid, 6 g of N-(hydroxymethyl)acrylamide, and 2.5 g of ammonium persulfate were dissolved in 625 mL of distilled water to obtain an aqueous phase. (3) The aqueous phase obtained in step (2) was slowly added to the organic phase, with the volume ratio of the aqueous phase to the organic phase being 1:3. After the addition, the mixture was stirred at 60°C and 100 rpm for 4 h, cooled to room temperature, centrifuged at 5000 rpm for 15 min, the precipitate was washed with anhydrous ethanol and deionized water, vacuum dried at 30°C, added to 10 times the weight of distilled water, rapidly frozen with liquid nitrogen, and freeze-dried at -60°C for 24 h to obtain porous modified polyacrylamide microspheres; (4) dissolving 6 g of sodium selenite in 600 mL of deionized water to obtain a sodium selenite solution, mixing the porous modified polyacrylamide microspheres obtained in step (3) with the sodium selenite solution, ultrasonicating at 300 W for 40 min, filtering, and vacuum drying to obtain selenium-loaded microspheres; (5) 4 g fulvic acid, 6 g sodium alginate and 30 g polyvinyl alcohol were added to 1 L deionized water, stirred at 80°C and 150 rpm for 30 min to obtain a mixed solution, the selenium-loaded microspheres obtained in step (4) were added to the mixed solution, stirred at 200 rpm for 1 h, and then added dropwise to a boric acid solution of calcium chloride, wherein the mass concentration of calcium chloride was 4 wt % and the mass concentration of boric acid was 3 wt %, stirred for 20 min, centrifuged at 5000 rpm for 20 min, the precipitate was washed with deionized water, and vacuum dried to obtain gel sustained-release microspheres; (6) Dissolve 15 g of dopamine hydrochloride in 1.5 L of 10 mM Tris-HCl buffer to obtain a dopamine solution with a concentration of 10 mg / mL, add the gel sustained-release microspheres obtained in step (5) to the dopamine solution, stir at 200 rpm for 2 h, filter, wash the filter cake with deionized water, and freeze-dry at -40°C to obtain selenium sustained-release microspheres.

[0034] The raw materials for preparing the natural composite extract include the following components in parts by weight: 5 parts of Hemiptera: ...

[0035] The preparation method of the natural composite extract comprises the following steps: (a) Wash and dry Hemiptera: Hemiptera: Hemiptera: Hemiptera: Hemiptera: Verbena: Ascophylla: Andrographis: Andrographis: Euphorbia: Euphorbia: Hemiptera ... -3 MPa to 20% of the original volume and freeze-dried at -40°C to obtain the natural water extract; (b) the filter residue obtained in step (a) was mixed evenly with 15 times the weight of deionized water, glucose and urea were added, the mass ratio of the filter residue, glucose and urea was 1:1.2:0.7, ultraviolet sterilization was performed to obtain a fermentation substrate, and the activated Bacillus inulinus was added at 10 7cfu / mL was inoculated into the fermentation substrate, and the culture was carried out at 80 r / min and 30°C for 48 h, cooled to room temperature, centrifuged at 5000 rpm for 20 min, and the supernatant was freeze-dried at -40°C to obtain the natural fermentation extract; (c) mixing the natural water extract obtained in step (a) and the natural fermentation extract obtained in step (b) in a mass ratio of 1:2 to obtain a natural composite extract.

[0036] This embodiment also provides a preparation method of the selenium-rich water-soluble compound fertilizer, comprising the following steps: adding 10 g of selenium slow-release microspheres, 8 g of natural compound extract, 1 g of potassium chloride, 1 g of monoammonium phosphate, 0.1 g of EDTA chelated zinc and 0.05 g of borax to 300 g of deionized water, stirring at 40° C. and 40 rpm for 1 h, and stirring at room temperature for 30 min to obtain a selenium-rich water-soluble compound fertilizer.

[0037] Example 3: A selenium-rich water-soluble compound fertilizer comprises the following components in parts by weight: 12 parts of selenium slow-release microspheres, 10 parts of natural compound extracts, 1.5 parts of potassium chloride, 2 parts of monoammonium phosphate, 0.15 parts of EDTA chelated zinc, 0.06 parts of borax, and 400 parts of deionized water.

[0038] The raw materials for preparing selenium sustained-release microspheres include the following components in parts by weight: 5 parts of rosmarinic acid, 2.5 parts of xylitol, 2.5 parts of itaconic acid, 8 parts of N-(hydroxymethyl)acrylamide, 30 parts of acrylamide, 7 parts of sodium selenite, 5 parts of fulvic acid, 7 parts of sodium alginate, 35 parts of polyvinyl alcohol, and 18 parts of dopamine hydrochloride.

[0039] The preparation method of selenium sustained-release microspheres comprises the following steps: (1) 5 g of rosmarinic acid and 2.5 g of xylitol were added to 150 mL of N,N-dimethylformamide and mixed evenly. 1 g of DMAP and 3 g of DCC were added. The mixture was stirred at 75°C and 180 rpm for 4.5 h. The mixture was cooled to room temperature and centrifuged at 8000 rpm for 18 min. The precipitate was washed with deionized water and dried in a vacuum at 65°C to obtain modified rosmarinic acid. (2) Under N2 protection, Span 60 and cyclohexane were mixed in a mass ratio of 1:300, and stirred at 40°C and 350 rpm for 45 min to obtain an organic phase. 30 g of acrylamide, modified rosmarinic acid, 2.5 g of itaconic acid, 8 g of N-(hydroxymethyl)acrylamide, and 3.6 g of ammonium persulfate were dissolved in 900 mL of distilled water to obtain an aqueous phase. (3) The aqueous phase obtained in step (2) was added slowly and continuously to the organic phase, with the volume ratio of the aqueous phase to the organic phase being 1:3.5. After the addition, the mixture was stirred at 65°C and 120 rpm for 4.5 h, cooled to room temperature, centrifuged at 5000 rpm for 18 min, the precipitate was washed with anhydrous ethanol and deionized water, vacuum dried at 30°C, added to 10 times the weight of distilled water, rapidly frozen with liquid nitrogen, and freeze-dried at -60°C for 26 h to obtain porous modified polyacrylamide microspheres; (4) dissolving 7 g of sodium selenite in 500 mL of deionized water to obtain a sodium selenite solution, mixing the porous modified polyacrylamide microspheres obtained in step (3) with the sodium selenite solution, ultrasonicating at 350 W for 45 min, filtering, and vacuum drying to obtain selenium-loaded microspheres; (5) Add 5 g of fulvic acid, 7 g of sodium alginate and 35 g of polyvinyl alcohol to 1 L of deionized water, stir at 85°C and 180 rpm for 30 min to obtain a mixed solution, add the selenium-loaded microspheres obtained in step (4) to the mixed solution, stir at 250 rpm for 1 h, add dropwise to a boric acid solution of calcium chloride, wherein the mass concentration of calcium chloride is 5 wt % and the mass concentration of boric acid is 3.5 wt %, stir for 25 min, centrifuge at 5000 rpm for 25 min, wash the precipitate with deionized water, and vacuum dry to obtain gel sustained-release microspheres; (6) 18 g of dopamine hydrochloride was dissolved in 1.8 L of 10 mM Tris-HCl buffer to obtain a dopamine solution with a concentration of 10 mg / mL. The gel sustained-release microspheres obtained in step (5) were added to the dopamine solution, stirred at 250 rpm for 2.5 h, filtered, and the filter cake was washed with deionized water and freeze-dried at -40°C to obtain selenium sustained-release microspheres.

[0040] The raw materials for preparing the natural composite extract include the following components in parts by weight: 6 parts of Hemiptera: ...

[0041] The preparation method of the natural composite extract comprises the following steps: (a) Wash and dry Hemiptera: Hemiptera: Hemiptera: Hemiptera: Hemiptera: Verbena: Ascophylla: Andrographis: Andrographis: Euphorbia: Euphorbia: Hemiptera ... -3 MPa to 20% of the original volume and freeze-dried at -40°C to obtain the natural water extract; (b) the filter residue obtained in step (a) was mixed evenly with 15 times the weight of deionized water, glucose and urea were added, the mass ratio of the filter residue, glucose and urea was 1:1.3:0.8, ultraviolet sterilization was performed to obtain a fermentation substrate, and the activated Bacillus inulinus was added at 10 7 cfu / mL was inoculated into the fermentation substrate, and the culture was carried out at 90 r / min and 30°C for 48 h, cooled to room temperature, centrifuged at 5000 rpm for 25 min, and the supernatant was freeze-dried at -40°C to obtain the natural fermentation extract; (c) uniformly mixing the natural water extract obtained in step (a) and the natural fermentation extract obtained in step (b) at a mass ratio of 1:2.5 to obtain a natural composite extract.

[0042] This embodiment also provides a preparation method of the selenium-rich water-soluble compound fertilizer, comprising the following steps: adding 12 g of selenium slow-release microspheres, 10 g of natural compound extract, 1.5 g of potassium chloride, 2 g of monoammonium phosphate, 0.15 g of EDTA chelated zinc and 0.06 g of borax into 400 g of deionized water, stirring at 40° C. and 50 rpm for 1 h, and stirring at room temperature for 30 min to obtain a selenium-rich water-soluble compound fertilizer.

[0043] The only difference between Comparative Example 1 and Example 1 is that no modified rosmarinic acid is added.

[0044] The only difference between Comparative Example 2 and Example 1 is that itaconic acid is not added.

[0045] The only difference between Comparative Example 3 and Example 1 is that the selenium sustained-release microspheres are replaced by gel sustained-release microspheres.

[0046] The only difference between Comparative Example 4 and Example 1 is that the natural water extract is used instead of the natural composite extract.

[0047] Experimental Example 1: Rice was used as the test plant, and 7 treatment groups were set up, each treatment group was repeated 3 times, and the selenium-rich water-soluble compound fertilizers of Examples 1-3 and Comparative Examples 1-4 were sprayed respectively, with an application rate of 10 L per mu each time. The blank group was sprayed with an equal amount of water, and the rice was sprayed once at the booting stage and the filling stage respectively. Conventional field management was performed, and the selenium content in the brown rice was analyzed after the rice matured. The results are as follows Figure 1 shown.

[0048] Figure 1The results showed that the selenium contents of Examples 1-3 and Comparative Examples 1-4 were higher than those of the control group, indicating that spraying the selenium-rich water-soluble compound fertilizer of the present invention can increase the selenium content of rice, and Examples 1-3 are higher than Comparative Examples 1-4. Among them, Comparative Example 1 did not add modified rosmarinic acid, the selenium loading amount decreased, and the effect of promoting plant absorption was reduced. Comparative Example 2 did not add itaconic acid, which reduced the selenium absorption effect of the plant. Comparative Example 3 did not use polydopamine for wrapping, and the adsorption of the leaves decreased, which was not conducive to the absorption and utilization of selenium. Comparative Example 4 did not add fermentation extract, and the selenium content in brown rice decreased.

[0049] Experimental Example 2: The selenium-rich water-soluble compound fertilizer of Example 1 and Comparative Examples 1-4 was sprayed once at the rice booting stage and the rice filling stage, with a dosage of 10 L per mu each time. The blank group was sprayed with an equal amount of water. The yield and fruit setting rate were recorded after the rice matured. The results are shown in Table 1.

[0050] Table 1:

[0051] The results in Table 1 show that the yield and fruit setting rate of Example 1 and Comparative Examples 1-4 are better than those of the control group, and Example 1 is better than Comparative Examples 1-4. Comparative Example 1 does not add modified rosmarinic acid, the chelating effect of selenium is reduced, the selenium loading is reduced, the effect of promoting plant selenium absorption is reduced, and the content of effective ingredients is reduced. Comparative Example 2 does not add itaconic acid, and the utilization rate of selenium is reduced. Comparative Example 3 does not encapsulate dopamine, and the adsorption capacity of leaves is reduced. Comparative Example 4 does not add fermentation extract, the content of effective ingredients is reduced, and the ability to increase plant yield is reduced.

[0052] Experimental Example 3: 1 g of each of the selenium-loaded microspheres prepared in Example 1 and the selenium sustained-release microspheres prepared in Example 1 were added to 200 ml of ultrapure water and sealed to protect from light. The sodium selenite content in the ultrapure water was measured after 1 day. Thereafter, the sodium selenite content in the ultrapure water was measured every 3 days for 21 consecutive days. The results are as follows: Figure 2 shown.

[0053] Figure 2 The results show that the selenium sustained-release microspheres prepared in Example 1 can slowly release sodium selenite, which is beneficial to improving the absorption and utilization rate of selenium, and can release it stably for a long time, which is beneficial to improving fertilizer efficiency.

[0054] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

Claims

1. A selenium-rich water-soluble compound fertilizer, characterized in that: The invention comprises the following components in parts by weight: 10-15 parts of selenium sustained-release microspheres, 8-12 parts of natural compound extracts, 1-2 parts of potassium chloride, 1-3 parts of monoammonium phosphate, 0.1-0.2 parts of EDTA chelated zinc, 0.05-0.08 parts of borax, and 300-500 parts of deionized water; The raw materials for preparing the selenium sustained-release microspheres include the following components in parts by weight: 4-6 parts of rosmarinic acid, 2-3 parts of xylitol, 2-3 parts of itaconic acid, 6-9 parts of N-(hydroxymethyl)acrylamide, 25-35 parts of acrylamide, 6-8 parts of sodium selenite, 4-6 parts of fulvic acid, 6-8 parts of sodium alginate, 30-40 parts of polyvinyl alcohol, and 15-20 parts of dopamine hydrochloride; The preparation method of the selenium sustained-release microspheres comprises the following steps: (1) adding rosmarinic acid and xylitol to N,N-dimethylformamide and mixing them evenly, adding DMAP and DCC, stirring to react, cooling, centrifuging, washing the precipitate, and drying to obtain modified rosmarinic acid; (2) Under the protection of N2, Span 60 and cyclohexane are mixed and stirred to obtain an organic phase, and acrylamide, modified rosmarinic acid, itaconic acid, N-(hydroxymethyl)acrylamide and ammonium persulfate are dissolved in distilled water to obtain an aqueous phase; (3) slowly adding the aqueous phase obtained in step (2) to the organic phase, stirring the reaction after the addition is complete, cooling, centrifuging, washing the precipitate, drying, adding 10 times the weight of distilled water, rapidly freezing with liquid nitrogen, and freeze-drying to obtain porous modified polyacrylamide microspheres; (4) dissolving sodium selenite in deionized water to obtain a sodium selenite solution, mixing the porous modified polyacrylamide microspheres obtained in step (3) with the sodium selenite solution, sonicating, filtering, and vacuum drying to obtain selenium-loaded microspheres; (5) adding fulvic acid, sodium alginate and polyvinyl alcohol into deionized water, stirring to obtain a mixed solution, adding the selenium-loaded microspheres obtained in step (4) into the mixed solution, stirring, and dropwise adding into a boric acid solution of calcium chloride, stirring, centrifuging, washing the precipitate, and vacuum drying to obtain gel sustained-release microspheres; (6) dissolving dopamine hydrochloride in Tris-HCl buffer to obtain a dopamine solution with a concentration of 10 mg / mL, adding the gel sustained-release microspheres obtained in step (5) to the dopamine solution, stirring, filtering, washing the filter cake with deionized water, and freeze-drying to obtain selenium sustained-release microspheres; The raw materials for preparing the natural composite extract include the following components in parts by weight: 5-7 parts of Hemiptera: 6-8 parts of Radix Scutellariae, 2-3 parts of Verbena officinalis, 8-12 parts of Ascophylla nodosum, 2-3 parts of Andrographis paniculata, and 4-6 parts of Eucheuma; The method for preparing the natural composite extract comprises the following steps: (a) Wash and dry Hemiptera: Hemiptera: Hemiptera: Hemiptera: Hemiptera: Verbena: Verbena: Ascophylla: Andrographis: Andrographis: Euphorbia: Euphorbia: Hemiptera ... (b) uniformly mixing the filter residue obtained in step (a) with 15 times the weight of deionized water, adding glucose and urea, sterilizing to obtain a fermentation substrate, inoculating the activated Bacillus inulinus into the fermentation substrate, fermenting, cooling, centrifuging, and freeze-drying the supernatant to obtain a natural fermentation extract; (c) uniformly mixing the natural water extract obtained in step (a) and the natural fermentation extract obtained in step (b) in a mass ratio of 1:2-3 to obtain a natural composite extract.

2. The selenium-rich water-soluble compound fertilizer according to claim 1, characterized in that In step (1), the mass concentration of xylitol in N,N-dimethylformamide is 16-20 mg / mL; the mass ratio of xylitol, DCC and DMAP is 1:1.2:0.

4.

3. The selenium-rich water-soluble compound fertilizer according to claim 2, characterized in that In step (2), the mass ratio of Span 60 to cyclohexane in the organic phase is 1:300; the amount ratio of acrylamide to deionized water in the aqueous phase is 1 g:25-35 mL; and the amount of ammonium persulfate is 10-15 wt % of acrylamide.

4. The selenium-rich water-soluble compound fertilizer according to claim 3, characterized in that In step (3), the volume ratio of the aqueous phase to the organic phase is 1:3-4.

5. The selenium-rich water-soluble compound fertilizer according to claim 4, characterized in that In step (4), the mass concentration of sodium selenite in deionized water is 10-16 mg / mL.

6. The selenium-rich water-soluble compound fertilizer according to claim 5, characterized in that In step (5), the mass concentration of the polyvinyl alcohol in deionized water is 30-40 mg / mL; the mass concentration of calcium chloride in the boric acid solution of calcium chloride is 4-6wt%, and the mass concentration of boric acid is 3-4wt%.

7. The selenium-rich water-soluble compound fertilizer according to claim 6, characterized in that In step (b), the mass ratio of the filter residue, glucose and urea is 1:1.2-1.5:0.7-1.

8. A method for preparing a selenium-rich water-soluble compound fertilizer according to any one of claims 1 to 7, characterized in that: The following steps are involved: Selenium slow-release microspheres, natural composite extracts, potassium chloride, monoammonium phosphate, EDTA-chelated zinc and borax were added into deionized water, stirred at 40°C for 1 h, and then stirred at room temperature for 30 min to obtain selenium-rich water-soluble composite fertilizer.

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