Alginic acid organic water-soluble fertilizer and preparation method thereof

Abstract

The invention relates to the technical field of water-soluble fertilizers, in particular to an amino-alginic acid organic water-soluble fertilizer and a preparation method thereof.The preparation method comprises the following steps that S1, one or more of macroelements, medium elements, microelements, amino acid and humic acid are dissolved to obtain a solution A; s2, adding nano silicon dioxide into the solution A, and uniformly dispersing to obtain a solution B; s3, adding sodium alginate into the solution B to obtain a colloidal solution C; s4, adding a stabilizer and a synergist into the colloidal solution C to obtain a colloidal solution D; s5, performing spray drying on the colloidal solution D to obtain solid powder E; s6, dissolving the degradable polymer, and adding a cross-linking agent to obtain a solution F; and S7, uniformly spraying the solution F onto the solid powder E, and performing spray drying to obtain the water-soluble fertilizer. According to the water-soluble fertilizer disclosed by the invention, the manner of coating the nanoparticles with the nanocapsules is adopted, so that the water-soluble fertilizer is efficiently utilized, and the yield and the quality of crops are improved.

Description

Technical Field

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

[0002] In agricultural production, farmers often increase crop yields by applying large amounts of nitrogen fertilizers, which results in the low nitrogen fertilizer utilization rate in my country, which is only about 35%, which is still far behind the world average. Urea has a high nitrogen content and is currently the most widely used and largest nitrogen fertilizer variety in my country, accounting for about 70% of the total nitrogen fertilizer consumption in the country. After urea is applied to the soil, except for a small part adsorbed by soil colloids, most of the rest is hydrolyzed and transformed under the action of soil urease. Some nitrogen is absorbed and utilized by crops or remains in the soil, and a considerable part of nitrogen is lost through leaching and volatilization, which has a great impact on the environment.

[0003] In recent years, through the modification and enhancement of conventional fertilizers, scholars have developed new fertilizer varieties such as coated slow-release fertilizers, encapsulated fertilizers, stable fertilizers, and urea-formaldehyde fertilizers, and have gradually promoted their application, which has played a positive role in improving the utilization rate of fertilizers in my country. At present, the modification and enhancement of urea mainly includes three categories: physical method, biological method and chemical method. Among them, the biological method is to add biologically active substances (such as alginic acid and amino acids) to urea to achieve the purpose of modification and enhancement. Alginic acid (Alginic acid), also known as alginic acid, is a natural polysaccharide polymer widely found in brown algae plants. It contains a large amount of non-nitrogenous organic matter, as well as a variety of mineral elements and rich vitamins and plant endogenous hormones. Through research, it is found that alginate as a fertilizer enhancer combined with urea can slow down the hydrolysis of urea and reduce the volatilization rate and loss of ammonia. The application of alginate synergistic compound fertilizer on wheat can achieve the effect of increasing yield by increasing the number of wheat spikes and grain quality, and can significantly promote the absorption and utilization of nutrients by wheat and improve fertilizer utilization. Applying alginate enhanced compound fertilizer on summer corn can improve fertilizer utilization rate, promote summer corn's absorption of nitrogen, phosphorus and potassium nutrients, and reducing the application amount by 10%-20% can ensure crop yield and soil fertility. Alginate can significantly increase corn yield and nitrogen absorption of grains, and improve the apparent utilization rate and agronomic efficiency of nitrogen fertilizer.

[0004] Although alginic acid has certain advantages as a fertilizer enhancer, there are also the following problems in practical applications: (1) When alginic acid combines with metal ions (such as calcium and magnesium) in the soil, it may form an insoluble gel, which will affect its effectiveness and long-term stability in the soil. This gelation process may limit its role as a synergist. (2) Alginic acid has strong hygroscopicity in a dry state, which may cause it to absorb water and clump during storage, affecting its uniformity of application and the stability of fertilizer effect. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of the present invention is to provide an alginate organic water-soluble fertilizer and a preparation method thereof that can improve storage stability and effectiveness of use. In addition, the alginate organic water-soluble fertilizer of the present application can further effectively control the release rate of nutrients in the fertilizer, delay the loss of nutrients, and reduce the rapid loss of fertilizer in the soil.

[0006] The present invention solves the technical problem by adopting the following technical solution: The present invention provides a method for preparing an organic water-soluble alginate fertilizer, which is characterized by comprising the following steps: S1: dissolving one or more of the macroelements, the secondary elements, the trace elements, the amino acids and the humic acid in distilled water, and stirring evenly to obtain a solution A; S2: Slowly add nano-silicon dioxide into solution A and disperse it evenly by ultrasonic to obtain solution B; S3: slowly add sodium alginate to solution B and continue stirring until a colloidal solution C is obtained after stirring evenly; S4: adjusting the colloidal solution C to be acidic, adding a stabilizer and a synergist to the colloidal solution C, and stirring evenly to obtain a colloidal solution D; S5: spray-drying the colloidal solution D to obtain a solid powder E; S6: After the degradable polymer is dissolved and stirred evenly, the solution is adjusted to be acidic, and then a cross-linking agent is added, and the solution F is obtained by stirring evenly again; S7: spraying the solution F uniformly onto the solid powder E to coat the solid powder E, and obtaining the solid powder G after spray drying, that is, obtaining the water-soluble fertilizer.

[0007] Preferably, the amount of nano-silicon dioxide in step S2 is 6-8% by weight of solution A. Preferably, the amount of sodium alginate used in step S3 is 1-3% of the weight of solution B.

[0008] Preferably, in step S4, the pH value of the colloidal solution C is adjusted to 5-7, the amount of the stabilizer is 0.2-3% by weight of the colloidal solution C, and the amount of the synergist is 2-5% by weight of the colloidal solution C.

[0009] Preferably, according to the method for preparing alginate organic water-soluble fertilizer according to claim 3, the stabilizer in step S4 is one or more of guar gum, hydroxypropyl methylcellulose, and polyvinyl alcohol, and the synergist is one or more of lactose, glycerol, and microcrystalline cellulose.

[0010] Preferably, the degradable polymer in step S6 is one or more of chitosan, gelatin, carboxymethyl cellulose, polyethylene glycol, and sodium alginate, and the weight percentage of the degradable polymer in the solution F is 5-10%.

[0011] Preferably, in step S6, the pH value of the degradable polymer solution is adjusted to 4-6.

[0012] Preferably, the cross-linking agent in step S6 is one or more of glutaraldehyde, carbodiimide, and phthalic acid, and the added amount of the cross-linking agent is 0.1-0.3% of the volume of solution F.

[0013] Preferably, in step S7, the weight ratio of solution F to solid powder G is (0.1-0.3):1.

[0014] Preferably, the alginate organic water-soluble fertilizer is prepared according to the preparation method of any one of claims 1-9.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) The alginate organic water-soluble fertilizer of the present invention uses nano-silicon dioxide and sodium alginate to adsorb and slowly release fertilizer nutrients. Nano-silicon dioxide has a large specific surface area, which can improve the solubility of the fertilizer, making it more dispersed in water and easier for plants to absorb. Sodium alginate has strong water absorption and water retention, and can form a protective film to slow down the release rate of fertilizer nutrients. The addition of sodium alginate can provide a slow-release effect for the fertilizer, so that the nutrients are gradually released during the growth of crops, avoiding the rapid release of traditional fertilizers. The nanoparticles made by combining the characteristics of sodium alginate can effectively regulate the release of fertilizers. The addition of synergists and stabilizers greatly improves the stability of the fertilizer during application, and can maintain its effectiveness under changing environmental conditions. (2) Using biodegradable polymers and cross-linking agents to encapsulate the fertilizer nutrients absorbed by nano-silicon dioxide and sodium alginate can effectively protect the active ingredients in the fertilizer and reduce their loss and volatilization in the soil. At the same time, the biodegradable polymers will absorb metal ions (such as calcium, magnesium, etc.) in the soil after absorbing water in the soil, thereby reducing the gelation of sodium alginate by metal ions, thereby affecting the efficiency of fertilizer use; (3) The alginate organic water-soluble fertilizer of the present invention is prepared by nanocapsule-coated nanoparticles, so that the water-soluble fertilizer can be efficiently utilized. By comprehensively utilizing ingredients and technical means such as sodium alginate, nano-silicon dioxide, synergists, stabilizers, and degradable polymers, the fertilizer can not only meet the diverse needs of plant growth, but also reduce resource waste and environmental pollution in agricultural production, improve crop yield and quality, and promote the long-term sustainable use of soil. Through spray drying, the fertilizer can be quickly dissolved when used, ensuring that nutrients can be absorbed by plants in a short time. The particles formed after drying are also easy to store and transport, reducing the risk of fertilizer agglomeration or deliquescence. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art description are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 is a Fourier transform infrared spectrum of solid powder E prepared in Example 2 of the present invention; Figure 2 The ammonium nitrogen (NH4 + -N), nitrate nitrogen (NO3 - -N), available phosphorus (AP), and available potassium (AK); Figure 3 The ammonium nitrogen (NH4 + -N), nitrate nitrogen (NO3 - -N), available phosphorus (AP), and available potassium (AK) leaching curves. DETAILED DESCRIPTION

[0018] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The basic raw materials of the water-soluble fertilizer used in this embodiment include the following raw materials in parts by weight: Macroelements: 25 parts of urea, 18 parts of potassium dihydrogen phosphate, 30 parts of potassium nitrate, 10 parts of potassium sulfate; Medium elements: 3 parts of magnesium sulfate, 4 parts of calcium sulfate; Trace elements: 0.5 parts of EDTA-manganese, 1 part of zinc sulfate, 0.5 parts of boric acid; Amino acids: 5 parts; Humic acid: 3 parts.

[0020] Example 1 S1: dissolving macroelements, secondary elements, trace elements, amino acids and humic acid in 80 parts of distilled water, stirring evenly, to obtain solution A; S2: Slowly add 11 parts of nano-silicon dioxide into solution A, and disperse evenly by ultrasonication to obtain solution B; S3: slowly add 2 parts of sodium alginate to solution B, continue stirring, and obtain colloidal solution C after stirring evenly; S4: adjusting the pH value of the colloidal solution C to 5-6, adding 0.4 parts of guar gum and 9 parts of lactose to the colloidal solution C, and stirring evenly to obtain a colloidal solution D; S5: spray-drying the colloidal solution D to obtain a solid powder E; S6: adding 5 parts of chitosan to 95 parts of 1% acetic acid solution and stirring to dissolve uniformly, adjusting the pH value of the solution to 4-5, adding 0.1 parts of glutaraldehyde, and stirring again to obtain a colloidal solution F; S7: The solution F is uniformly sprayed onto the solid powder E to coat the solid powder E, and the solid powder G is obtained after spray drying, that is, the water-soluble fertilizer is obtained, wherein the weight ratio of the solution F to the solid powder G is 0.2:1.

[0021] Example 2 S1: dissolving macroelements, secondary elements, trace elements, amino acids and humic acid in 80 parts of distilled water, stirring evenly, to obtain solution A; S2: Slowly add 14 parts of nano-silicon dioxide to solution A, and disperse evenly by ultrasonication to obtain solution B; S3: Slowly add 5.5 parts of sodium alginate to solution B, continue stirring, and obtain colloidal solution C after stirring evenly; S4: adjusting the pH value of the colloidal solution C to 5-6, and adding 0.1 parts of guar gum, 5 parts of hydroxypropyl methylcellulose, and 4 parts of glycerin to the colloidal solution C, and stirring evenly to obtain a colloidal solution D; S5: spray-drying the colloidal solution D to obtain a solid powder E; S6: adding 2 parts of chitosan and 3 parts of gelatin to 95 parts of 1% acetic acid solution and stirring to dissolve uniformly, adjusting the pH value of the solution to 4-5, adding 0.2 parts of carbodiimide, and stirring again to obtain a gel solution F; S7: The solution F is uniformly sprayed onto the solid powder E to coat the solid powder E, and the solid powder G is obtained after spray drying, that is, the water-soluble fertilizer is obtained, wherein the weight ratio of the solution F to the solid powder G is 0.3:1.

[0022] Example 3 S1: dissolving macroelements, secondary elements, trace elements, amino acids and humic acid in 80 parts of distilled water, stirring evenly, to obtain solution A; S2: Slowly add 12.5 parts of nano-silicon dioxide into solution A, and disperse evenly by ultrasonication to obtain solution B; S3: Slowly add 4.8 parts of sodium alginate to solution B, continue stirring, and obtain colloidal solution C after stirring evenly; S4: adjusting the pH value of the colloidal solution C to 6-7, adding 6 parts of polyvinyl alcohol and 5.5 parts of microcrystalline cellulose to the colloidal solution C, and stirring evenly to obtain a colloidal solution D; S5: spray-drying the colloidal solution D to obtain a solid powder E; S6: Add 5 parts of gelatin and 3 parts of polyethylene glycol to 92 parts of 1% acetic acid solution and stir to dissolve uniformly, adjust the pH value of the solution to 5-6, then add 0.1 parts of glutaraldehyde, and stir again to obtain a colloidal solution F, wherein the molecular weight of the polyethylene glycol is 1000; S7: The solution F is uniformly sprayed onto the solid powder E to coat the solid powder E, and the solid powder G is obtained after spray drying, that is, the water-soluble fertilizer is obtained, wherein the weight ratio of the solution F to the solid powder G is 0.1:1.

[0023] Example 4 S1: dissolving macroelements, secondary elements, trace elements, amino acids and humic acid in 80 parts of distilled water, stirring evenly, to obtain solution A; S2: Slowly add 12.5 parts of nano-silicon dioxide into solution A, and disperse evenly by ultrasonication to obtain solution B; S3: Slowly add 4.8 parts of sodium alginate to solution B, continue stirring, and obtain colloidal solution C after stirring evenly; S4: adjusting the pH value of the colloidal solution C to 6-7, and adding 0.4 parts of guar gum and 8 parts of glycerol to the colloidal solution C and stirring evenly to obtain a colloidal solution D; S5: spray-drying the colloidal solution D to obtain a solid powder E; S6: Add 5 parts of gelatin and 1 part of sodium alginate to 94 parts of 1% acetic acid solution and stir to dissolve evenly, adjust the pH value of the solution to 5-6, then add 0.1 parts of glutaraldehyde and 0.1 parts of carbodiimide, and stir again to obtain a gel solution F; S7: The solution F is uniformly sprayed onto the solid powder E to coat the solid powder E, and the solid powder G is obtained after spray drying, that is, the water-soluble fertilizer is obtained, wherein the weight ratio of the solution F to the solid powder G is 0.3:1.

[0024] Example 5 S1: dissolving macroelements, secondary elements, trace elements, amino acids and humic acid in 80 parts of distilled water, stirring evenly, to obtain solution A; S2: Slowly add 10.8 parts of nano-silicon dioxide into solution A, and disperse evenly by ultrasonication to obtain solution B; S3: Slowly add 5.5 parts of sodium alginate to solution B, continue stirring, and obtain colloidal solution C after stirring evenly; S4: adjusting the pH value of the colloidal solution C to 5-6, and adding 0.4 parts of guar gum, 3 parts of lactose, and 7 parts of glycerol to the colloidal solution C and stirring evenly to obtain a colloidal solution D; S5: spray-drying the colloidal solution D to obtain a solid powder E; S6: Add 3 parts of gelatin and 5 parts of carboxymethyl cellulose to 92 parts of 1% acetic acid solution and stir to dissolve evenly, adjust the pH value of the solution to 5-6, then add 0.3 parts of phthalic acid, and stir again to obtain a colloidal solution F; S7: The solution F is uniformly sprayed onto the solid powder E to coat the solid powder E, and the solid powder G is obtained after spray drying, that is, the water-soluble fertilizer is obtained, wherein the weight ratio of the solution F to the solid powder G is 0.3:1.

[0025] The raw materials used in Examples 1 to 5 are shown in Table 1.

[0026] Table 1 Ratio of raw materials used in Example 1-Example 5

[0027] Comparative Example 1 The difference between this comparative example and Example 2 is that no nano-silicon dioxide is added in step S2.

[0028] Comparative Example 2 The difference between this comparative example and Example 2 is that the weight ratio of solution F to solid powder G in step S2 is 0.5:1.

[0029] Comparative Example 3 The difference between this comparative example and Example 2 is that guar gum, hydroxypropyl methylcellulose and glycerin are not added in step S4.

[0030] Comparative Example 4 The difference between this comparative example and Example 2 is that glycerol is not added in step S4.

[0031] Comparative Example 5 The difference between this comparative example and Example 2 is that step S6 and step S7 are not performed.

[0032] Comparative Example 6 The difference between this comparative example and Example 2 is that step S3 and step S4 are not performed.

[0033] Comparative Example 7 The difference between this comparative example and Example 2 is that steps S5 and S7 are not performed, the colloidal solution D prepared in step S4 and the colloidal solution F prepared in step S7 are mixed and stirred evenly and then spray-dried, and the mixing ratio is converted according to the weight of the colloidal solution D before and after spray drying, so that the ratio of the effective substance in the colloidal solution D to the colloidal solution F is consistent with that in Example 2.

[0034] Comparative Example 8 Use only basic fertilizer.

[0035] Comparative Example 9 No fertilization was performed.

[0036] The raw material usage ratios of Example 2 and Comparative Examples 1 to 6 are shown in Table 2 and Table 3.

[0037] Table 2 Ratio of raw materials used in Example 2 and Comparative Examples 1-3

[0038] Table 3 Ratio of raw materials used in Example 2 and Comparative Examples 4-6

[0039] Experimental Design The experiment was conducted in the experimental field of Qingzhou City, Weifang City, Shandong Province from May to September 2024. The region has a temperate monsoon climate, with annual rainfall mainly concentrated in June-September, an average annual rainfall of about 600-800 mm, an average annual temperature of about 12-14 °C, and a winter wheat-summer corn rotation. The soil type for the test was brown soil, and its basic physical and chemical properties are shown in Table 3. The corn variety for the test was Weiyu No. 8.

[0040] Soil sample collection: Randomly select 5 points in each treatment plot to collect mixed soil samples with a thickness of 0-50 cm; then mix the soil evenly, take some fresh samples to immediately determine the soil moisture content, nitrate nitrogen and ammonium nitrogen content, and the rest of the soil is naturally air-dried and then ground through a 2 mm sieve and stored for testing. The basic physical and chemical properties of the test soil are shown in Table 4.

[0041] Soil samples: total nitrogen content was determined by Kjeldahl method, alkaline hydrolysis nitrogen was determined by alkaline hydrolysis diffusion method, water content was determined by drying and weighing method, nitrate nitrogen and ammonium nitrogen content were determined by 2 mol·L -1The solution was extracted with KCl and determined by flow injection analyzer, the available phosphorus was determined by 0.5 M sodium bicarbonate method, and the available potassium was extracted with NH4OAc and determined by flame photometer.

[0042] Table 4 Basic physical and chemical properties of the tested soil

[0043] The test fertilizers were the fertilizers prepared in Examples 1-5 and Comparative Examples 1-8, and the amount of the basic fertilizer of each test fertilizer remained unchanged. Corn planting density 70,000 plants / hm -2 The nitrogen application rate for each treatment was 200 kg·hm -2 The experiment was sown on May 11, 2024 and harvested on September 3. Conventional management measures were adopted during the planting period. The area of ​​the plot is 4m×5m=20m 2 , repeated 3 times, arranged in random blocks.

[0044] Plant sample collection: 10 plants were collected at the maturity stage of corn according to the sampling method of taking 1 plant out of every 10 plants. The whole plant was separated by parts (stalk, leaf, ear) and brought back to the laboratory; at the same time, the number of ear rows and the number of grains per ear were investigated, the ear mass was weighed and threshed after air drying, the 100-grain weight was measured and the grain yield was calculated. The samples of various parts and grains of corn were fixed at 105℃ for 30 minutes, placed in an oven set at 80℃ and dried to constant weight, and the dry matter mass was weighed; the samples of various parts were ground for testing.

[0045] Measurement items and methods 1. Characterization of fertilizer functional group structure The infrared spectrum of the sample was measured by Fourier transform infrared spectrometer using KBr tablet method, and the test range was 400-4000cm -1 Resolution 1.5cm -1 .

[0046] In this application, the solid powder E prepared in Example 2 was characterized as follows: Figure 1 ,from Figure 1 The middle curve shows that it is located at 1778cm -1 The absorption peak corresponds to the asymmetric stretching vibration peak of -COO, 1135cm -1 It is the asymmetric stretching vibration peak of -C-O-, located at 989cm -1 The absorption peak corresponds to the stretching vibration of O—Si—O in the sample, which is located at 467 cm -1 The absorption peak is the bending vibration of O—Si—O, located at 1092cm -1 The strong absorption peak corresponds to the asymmetric vibration of Si—O—Si in the sample. -1, 989cm -1 , 1135cm -1 , 1778cm -1 , 1092cm -1 The absorption peak is quite obvious, indicating that the solid powder E contains nano-silica modified with sodium alginate.

[0047] 2. Determination of leaching characteristics The leaching test was used for determination. An acrylic transparent PVC cylindrical tube with an inner diameter of 5 cm, a height of 60 cm and multiple 1 mm holes at the bottom was prepared. A filter device was laid at the bottom in the order of nylon mesh (300 mesh), quartz sand (6-8 mesh, thickness 3 cm), and nylon mesh (300 mesh). The test fertilizer containing 8 g of basic fertilizer was mixed with 1100 g of test soil to fill the soil. A 100 mL triangular flask was placed under the soil column to collect the leaching solution. After the soil was filled, the soil at the edge was compacted. In order to evenly distribute water, 2 layers of nylon mesh (300 mesh) were laid on the soil surface, and 3 mm thick quartz sand was filled on the top to reduce the disturbance of water flow to the soil surface.

[0048] An intermittent leaching method was adopted with an interval of 7 days, and a total of 8 leachings were carried out. Water was added for the first time until the soil moisture content of the soil column reached the critical saturated moisture content. Referring to the single rainfall in Qingzhou City from June to September, the single precipitation of a single soil column was converted to 46mL of deionized water. The dosage was based on the field dosage, and 155mL of water was added for the first time, and deionized water was used. The leaching test was carried out after stabilization for 24 hours. After that, 46mL of deionized water was injected for each leaching, and the leachate was collected. After that, a leaching test was carried out every 7 days. After the first leaching, the collected leaching solution was filtered to test the nitrate nitrogen (NO3 - -N), ammonium nitrogen (NH4 + -N), available phosphorus (AP), available potassium (AK), nitrate nitrogen (NO3 - -N), ammonium nitrogen (NH4 + -N), available phosphorus (AP) were determined by flow analyzer, and available potassium (AK) was determined by flame photometer. Leaching loss (mg) = [ammonium nitrogen concentration of each elution solution (mg / L) * volume of each elution solution (L)].

[0049] Figure 2 The ammonium nitrogen (NH4 + -N), nitrate nitrogen (NO3 - -N), available phosphorus (AP), and available potassium (AK); Figure 3 The ammonium nitrogen (NH4 + -N), nitrate nitrogen (NO3 --N), available phosphorus (AP), and available potassium (AK) leaching curves.

[0050] according to Figure 2 , Figure 3 It shows that the alginate organic water-soluble fertilizers prepared in Examples 1 to 5 can significantly reduce the amount of ammonium nitrogen (NH4 + -N), nitrate nitrogen (NO3 - It reduces the leaching loss of available phosphorus (AP) and quick-acting potassium (AK), improves the water solubility and stability of the fertilizer, ensures the long-term effectiveness of the active ingredients in the fertilizer, and improves the use efficiency of the fertilizer.

[0051] use 15 The method of combining nitrogen tracing technology with field experiments was used to study the effects of water-soluble fertilizer application on nitrogen absorption, utilization, distribution and fate of corn. 15 N urea was purchased from Shanghai Yien Chemical Technology Co., Ltd. with an abundance of 10%. 15 The N test was embedded in the corresponding treatment plot, with a micro-area area of ​​0.4m×0.4m×3.14≈0.5m2. The test plot was made of acrylic material into a cylinder with a height of 70cm and a diameter of 80cm. The cylinder was buried 60cm in the soil, and the surface was 10cm above the ground to prevent the horizontal migration of nutrients caused by irrigation. Specific operation: a circular pit with a diameter of 80cm and a height of 60cm was dug in the field, and the excavated soil was stored separately according to 0-20, 20-40, and 40-60cm to prevent mixing; the cylinder was placed in the circular pit, and the excavated soil was backfilled in layers and compacted; then water was poured to settle. 15 Four maize plants were planted in each N microplot, and the fertilizer application and field management were the same as those in the field plots.

[0052] Table 5 shows the effects of the fertilizers prepared by Examples 1 to 5 and Comparative Examples 1 to 9 on corn yield; Table 6 shows the effects of the fertilizers prepared by Examples 1 to 5 and Comparative Examples 1 to 9 on the absorption and utilization of nutrients in corn; Table 7 shows the effects of the fertilizers prepared by Examples 1 to 5 and Comparative Examples 1 to 8 on the accumulation of fertilizers in different parts of corn.

[0053] Table 5 Effect of the fertilizers prepared by Example 1-Example 5 and Comparative Example 1-Comparative Example 9 on corn yield

[0054] Table 6 shows the effects of the fertilizers prepared in Examples 1 to 5 and Comparative Examples 1 to 9 on the absorption and utilization of nutrients in corn

[0055] Table 7 shows the effects of the fertilizers prepared in Examples 1 to 5 and Comparative Examples 1 to 8 on the accumulation of fertilizers in different parts of corn

[0056] It can be concluded from Tables 5 to 7 that the alginate organic water-soluble fertilizer of the present application can promote corn's absorption and utilization of soil nitrogen and fertilizer nitrogen, greatly increasing the total nitrogen and fertilizer nitrogen absorbed by corn compared to the use of basic fertilizers, thereby increasing corn yields.

[0057] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0058] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing an organic water-soluble alginic acid fertilizer, characterized in that: The following steps are involved: S1: dissolving one or more of the macroelements, the secondary elements, the trace elements, the amino acids and the humic acid in distilled water, and stirring evenly to obtain a solution A; S2: Slowly add nano-silicon dioxide into solution A and disperse it evenly by ultrasonic to obtain solution B; S3: slowly add sodium alginate to solution B and continue stirring until a colloidal solution C is obtained after stirring evenly; S4: adjusting the colloidal solution C to be acidic, adding a stabilizer and a synergist to the colloidal solution C, and stirring evenly to obtain a colloidal solution D; S5: spray-drying the colloidal solution D to obtain a solid powder E; S6: After the degradable polymer is dissolved and stirred evenly, the solution is adjusted to be acidic, and then a cross-linking agent is added, and the solution F is obtained by stirring evenly again; S7: spraying the solution F uniformly onto the solid powder E to coat the solid powder E, and obtaining the solid powder G after spray drying, that is, obtaining the water-soluble fertilizer.

2. The method for preparing the alginate organic water-soluble fertilizer according to claim 1, characterized in that: The amount of nano-silicon dioxide used in step S2 is 6-8% by weight of solution A.

3. The method for preparing the alginate organic water-soluble fertilizer according to claim 2, characterized in that: The amount of sodium alginate used in step S3 is 1-3% of the weight of solution B.

4. The method for preparing alginate organic water-soluble fertilizer according to claim 3, wherein in step S4, the pH value of the colloidal solution C is adjusted to 5-7, the amount of the stabilizer is 0.2-3% by weight of the colloidal solution C, and the amount of the synergist is 2-5% by weight of the colloidal solution C.

5. The method for preparing alginate organic water-soluble fertilizer according to claim 3, wherein the stabilizer in step S4 is one or more of guar gum, hydroxypropyl methylcellulose, and polyvinyl alcohol, and the synergist is one or more of lactose, glycerol, and microcrystalline cellulose.

6. The method for preparing alginate organic water-soluble fertilizer according to claim 1, wherein the degradable polymer in step S6 is one or more of chitosan, gelatin, carboxymethyl cellulose, polyethylene glycol, and sodium alginate, and the weight percentage of the degradable polymer in the solution F is 5-10%.

7. The method for preparing alginate organic water-soluble fertilizer according to claim 6, wherein in step S6, the pH value of the degradable polymer solution is adjusted to 4-6.

8. The method for preparing alginate organic water-soluble fertilizer according to claim 6, wherein the cross-linking agent in step S6 is one or more of glutaraldehyde, carbodiimide, and phthalic acid, and the amount of the cross-linking agent added is 0.1-0.3% of the volume of solution F.

9. The method for preparing alginate organic water-soluble fertilizer according to claim 6, wherein the weight ratio of solution F to solid powder G in step S7 is (0.1-0.3):

1.

10. Alginate organic water-soluble fertilizer, characterized in that: The alginate organic water-soluble fertilizer is prepared according to the preparation method of any one of claims 1 to 9.

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