Fertilizer synergist and preparation method thereof

Abstract

The invention provides a fertilizer synergist and a preparation method thereof, and belongs to the technical field of fertilizer synergism, the fertilizer synergist is prepared from the following raw material components: 10 parts of an organic coated composite synergistic component, 20-30 parts of modified diatomite, 1-3 parts of plant ash, 0.2-0.4 part of potassium sulfate and 2-3 parts of water, wherein the modified diatomaceous earth is prepared by sequentially modifying diatomaceous earth with a citric acid solution and a sodium polyacrylate solution. According to the fertilizer synergist provided by the invention, through mutual cooperation of all the components, the heavy metal content of crop plants can be effectively reduced while efficient utilization of fertilizer nutrients is realized, and the fertilizer synergist is suitable for planting of vegetables and grain crops in heavy metal polluted cultivated lands and has excellent fertilizer efficiency enhancement and heavy metal remediation effects.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fertilizer synergism, and particularly relates to a fertilizer synergist and a preparation method thereof. BACKGROUND

[0002] At present, although the large use of chemical fertilizers can achieve yield increase, the hydrolysis speed of the chemical fertilizers after application is too fast, which can easily cause many problems, such as excessive heavy metals in cultivated land, serious organic pollution, environmental pollution, etc., not only wasting resources and increasing planting costs, but also affecting the nutrient absorption of crops, reducing the utilization efficiency of fertilizers, deteriorating the land properties in many places, exceeding the standard of heavy metals in soil, and causing food safety problems.

[0003] The synergist can improve soil fertility, promote plant growth and full utilization of nutrients, for example, adding a nitrogen fertilizer synergist in the fertilizer can slow down the decomposition and release speed of urea, increase the content of ammonium nitrogen in soil, and better meet the nitrogen demand of plants in the growth curve, humic acid fertilizer has the effects of improving the utilization rate of chemical fertilizers and reducing environmental pollution, humic acid and urea can form a stable chemical bond, thereby reducing the release rate and loss of nitrogen, indirectly increasing the content of nitrogen in soil, and improving the utilization rate of nitrogen fertilizer. However, these synergists can only improve soil fertility, and are difficult to fundamentally improve the physical, chemical and biological properties of soil, and cannot effectively solve the existing heavy metal pollution at present, and the microbial activity and enzyme activity are strong, the synergist is easily degraded by microorganisms in soil, and the beneficial effect on plants is not ideal.

[0004] Therefore, how to improve the heavy metal pollution problem while improving the soil fertility of the synergist, and ensure food safety on the basis of solving the yield problem of crops, which has very important significance for crop planting and ecological management of soil. SUMMARY

[0005] In order to solve the problems in the background art, the application provides a fertilizer synergist and a preparation method thereof, which can improve the heavy metal pollution problem while improving the soil fertility.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the application is as follows: A fertilizer synergist, by weight, comprising the following raw material components: 10 parts of an organic coated composite synergistic component, 20-30 parts of modified diatomite, 1-3 parts of wood ash, 0.2-0.4 parts of potassium sulfate, and 2-3 parts of water, wherein the modified diatomite is prepared by sequentially modifying diatomite with a citric acid solution and a sodium polyacrylate solution.

[0007] Further, the preparation of the organic coated composite synergistic component comprises the following steps: A1. Add lactic acid and ethylene glycol into a reactor, control the pressure and temperature, stir until uniform, then add terephthalic acid and concentrated sulfuric acid, heat to 140-160℃, stir for 6-10h, cool to room temperature, obtain preformed material, ready for use; A2. Dissolve starch in a mixed solution containing water and 1,4-dioxane, add sodium hydroxide to adjust the pH to 9-10, heat to 60-70℃ for gelatinization, then add propylene glycol trimethyl ammonium chloride, react for 2-3h, after the reaction is completed, add acid to adjust the pH to neutral, concentrate and dry to obtain cationic starch; A3. Add the cationic starch prepared in step A2 to the composite synergistic component, stir until uniform, obtain pre-reaction liquid, then add microcrystalline wax and the preformed material prepared in step A1, mix uniformly, adjust the pH of the system to 4-5 with a 70-80% mass fraction phosphoric acid solution, add ethylene glycol diglycidyl ether, heat to 50-60℃, stir for 1-2h, concentrate and dry to obtain an organic coated composite synergistic component, wherein the composite synergistic component is prepared from γ-polyglutamic acid, polyaspartic acid and inulin.

[0008] Further, in step A1, the mass ratio of lactic acid to ethylene glycol is 1:2, and the addition amounts of terephthalic acid and concentrated sulfuric acid are 4-6% and 1.5-2.5% of the mass of lactic acid, respectively.

[0009] Further, in step A2, the mass ratio of starch to mixed solution is 1:2-3, and the mass ratio of water to 1,4-dioxane in the mixed solution is 1:1.

[0010] Further, in step A3, the mass ratio of composite synergistic component, cationic starch and preformed material is 100:1.8-2.2:1-2, and the mass ratio of cationic starch, microcrystalline wax and ethylene glycol diglycidyl ether is 1:0.08-0.12:2-4.

[0011] Further, in step A3, the preparation method of the composite synergistic component is as follows: dissolve 5 parts of γ-polyglutamic acid and 2-3 parts of polyaspartic acid in 40-60 parts of a 1-2% mass fraction sodium alginate solution, then add 0.8-1.2 parts of inulin, while stirring, add 0.2-0.3 parts of acetic acid dropwise, after the dropwise addition is completed, stir for 15-25min to obtain the composite synergistic component.

[0012] Further, the preparation of modified diatomite includes the following contents: B1. Prepare a citric acid solution with a mass concentration of 0.1-0.3g / L, stir diatomite with the citric acid solution, mix thoroughly, obtain mixed slurry, dry the mixed slurry after standing to obtain pretreated diatomite; B2. Configure the mass concentration of 0.05-0.2g / L of the sodium polyacrylate solution, stir the pretreated diatomite with the sodium polyacrylate solution, mix thoroughly, adjust the slurry to neutral, obtain the modified mud, dry the modified mud after standing, grind and crush to obtain the modified diatomite.

[0013] Further, the mass ratio of diatomite to citric acid solution in step B1 is 100:3.8-4.2.

[0014] Further, the pretreated diatomite and the sodium polyacrylate solution in step B2 are mixed according to the mass ratio of 100:4-6.

[0015] The application also provides a preparation method of the fertilizer synergist, for preparing the fertilizer synergist described in the above scheme, comprising the following steps: S1. Mix the organic coated composite synergistic component and the modified diatomite uniformly, add half amount of water, stir for 3-8min to obtain a premix; S2. Mix the remaining raw materials uniformly, then add the premix of step S1, heat to 50-60℃, stir for 10-20min, concentrate and dry to obtain the fertilizer synergist. 1. In the fertilizer synergist of the application, the organic coated composite synergistic component is prepared by organic coating based on γ-polyglutamic acid, polyaspartic acid and inulin, which, together with the modified diatomite, can build a slow-release nutrient system on one hand, reduce nutrient loss problems such as nitrogen volatilization and phosphorus fixation, and on the other hand, capture free heavy metal ions in the soil through chelating groups to form stable chelates, greatly strengthening the heavy metal fixation effect; grass ash contains rich potassium carbonate, calcium oxide and other ingredients, which can adjust the soil pH and promote the formation of heavy metal ions into insoluble precipitates; potassium sulfate as an auxiliary nutrient supplement can replace the heavy metal ions adsorbed on the soil colloids through ion exchange, making them more easily captured by the modified diatomite and the organic coated component.

[0016] 2. Diatomite has multiple functions of promoting nutrient absorption, slow-release silicate and chelating heavy metals due to its unique physicochemical properties (porous structure, high specific surface area, surface active groups, etc.), and its surface functionalization and increased structural porosity can be achieved by modification, which can improve its adsorption capacity for heavy metals, retain moisture and fertilizer, and increase crop yield; citric acid is a weak organic acid with three carboxyl groups, which can form stable complexes with metal ions, and impurities in diatomite (such as aluminum oxide and iron oxide) can be dissolved and leached by citric acid, thereby dredging the pores and increasing the specific surface area; sodium polyacrylate is a macromolecular polymer that forms long chains after dispersion in water, which links individual diatomite with a single house structure to make the diatomite structure more stable and enhance the uniformity of surface grafting. At the same time, sodium polyacrylate forms hydrogen bonds or ionic bonds with the hydroxyl groups on the surface of diatomite through carboxyl groups (-COO - ), which enhances the crosslinking density of the composite, improves the three-dimensional network structure, and improves the water retention capacity and structural stability.

[0017] 3. The organic coated composite synergistic component is prepared by compounding and coating with organic preform and cationic starch synergistic component. The release amount of the fertilizer can be controlled according to the soil environment, and the fertilizer has slow-release performance, which improves the utilization rate of the fertilizer and retains more water and fertility in the soil. In addition, the modified diatomite has high surface negative charge density and good microstructure dispersion, which can interact with the organic coating layer to form a stable steric hindrance on the surface of the diatomite particles, preventing the soil particles from contacting each other to form flocs, avoiding accumulation and blockage, and at the same time making the diatomite mineral not easy to be dissolved, improving the structural stability in the solution environment, and significantly improving the adsorption effect of diatomite and inulin on heavy metal ions, and significantly reducing the content of heavy metals in plants. DETAILED DESCRIPTION

[0018] The application will be further described in detail below in conjunction with the examples.

[0019] The raw materials of the examples and comparative examples of the application are all ordinary commercial products unless otherwise specified.

[0020] Example 1: A fertilizer synergist is prepared from the following raw material components: 10 parts of organic coated composite synergistic component, 25 parts of modified diatomite, 2 parts of wood ash, 0.3 parts of potassium sulfate and 2.5 parts of water. The specific preparation method includes the following steps: S1. Mix the organic coated composite synergistic component and the modified diatomite uniformly, add half of the amount of water, and stir for 5 min to obtain a premix; S2. Mix the remaining other raw materials uniformly, then add the premix of step S1, heat to 55°C, and stir for 15 min to concentrate and dry to obtain the fertilizer synergist.

[0021] The preparation of the organic coated composite synergistic component includes the following steps: A1, lactic acid and ethylene glycol are added into a reactor according to a mass ratio of 1:2, the pressure is controlled at 5 kPa, heated to 125 DEG C, stirred for 15 min, then terephthalic acid and concentrated sulfuric acid are added, the addition amount of terephthalic acid and concentrated sulfuric acid is 5% and 2% of the mass of lactic acid respectively, heated to 150 DEG C, stirred for 8 h, and then cooled to room temperature to obtain a preformed material for standby; A2, starch is dissolved in a mixed solution containing water and 1, 4-dioxane, wherein the mass ratio of starch to mixed solution is 1:2.5, the mass ratio of water to 1, 4-dioxane in the mixed solution is 1:1, then sodium hydroxide is added to adjust the pH to 9-10, heated to 65 DEG C for gelatinization, then propyltrimethylammonium chloride is added for reaction for 2.5 h, the addition amount of propyltrimethylammonium chloride is 5% of the mass of starch, after the reaction is completed, acid is added to adjust the pH to neutral, concentrated and dried to obtain cationic starch; A3, the cationic starch obtained in step A2 is added into the composite synergistic component and stirred uniformly to obtain a pre-reaction solution, then microcrystalline wax and the preformed material prepared in step A1 are added and mixed uniformly, the pH of the system is adjusted to 4-5 with a 75% phosphoric acid solution, ethylene glycol diglycidyl ether is added, heated to 55 DEG C, stirred for 1.5 h, concentrated and dried to obtain the organic coated composite synergistic component, wherein the composite synergistic component is prepared from gamma-polyglutamic acid, polyaspartic acid and inulin, the mass ratio of the composite synergistic component, cationic starch and preformed material is 100:2:1.5, and the mass ratio of cationic starch, microcrystalline wax and ethylene glycol diglycidyl ether is 1:0.1:3.

[0022] The preparation method of the composite synergistic component in step A3 is as follows: 5 parts of gamma-polyglutamic acid and 2.5 parts of polyaspartic acid are dissolved in 50 parts of a 1.5% sodium alginate solution, then 1 part of inulin is added, while stirring, 0.25 parts of acetic acid is added dropwise, after the dropwise addition is completed, stirring is continued for 20 min to obtain the composite synergistic component.

[0023] The preparation of the modified diatomite includes the following contents: B1. A citric acid solution with a mass concentration of 0.2 g / L is prepared, diatomite and the citric acid solution are stirred according to a mass ratio of 100:4, fully mixed, and then the mixed slurry is dried after standing to obtain pretreated diatomite; B2. A sodium polyacrylate solution with a mass concentration of 0.1 g / L is prepared, the pretreated diatomite and the sodium polyacrylate solution are stirred according to a mass ratio of 100:5, fully mixed, and then the slurry is adjusted to neutral to obtain modified mud, the modified mud is dried after standing, ground and crushed into a 200-mesh powder to obtain modified diatomite.

[0024] Embodiment 2: a fertilizer synergist prepared from the following raw material components: 10 parts of organic coated composite synergist component, 20 parts of modified diatomite, 1 part of wood ash, 0.2 part of potassium sulfate and 2 parts of water, and the specific preparation method comprises the following steps: S1. uniformly mix the organic coated composite synergist component and the modified diatomite, add half of the amount of water, stir for 3 min, and obtain a premix; S2. uniformly mix the remaining other raw materials, then add the premix of step S1, heat to 50℃, stir for 20 min, concentrate, dry, and obtain the fertilizer synergist.

[0025] Preparation of the organic coated composite synergist component comprises the following steps: A1. add lactic acid and ethylene glycol in a mass ratio of 1:2 into a reactor, control the pressure to be 4 kPa, heat to 120℃, stir for 1.5 h, then add terephthalic acid and concentrated sulfuric acid, the addition amount of terephthalic acid and concentrated sulfuric acid is 4% and 1.5% of the mass of lactic acid respectively, heat to 140℃, stir for 10 h, and then reduce to room temperature to obtain a pre-preparation; A2. dissolve starch in a mixed solution containing water and 1,4-dioxane, wherein the mass ratio of starch to the mixed solution is 1:2, and the mass ratio of water to 1,4-dioxane in the mixed solution is 1:1, then add sodium hydroxide to adjust the pH to 9-10, heat to 60℃ for gelatinization, add epoxypropyltrimethylammonium chloride for reaction for 3 h, the addition amount of epoxypropyltrimethylammonium chloride is 4% of the mass of starch, after the reaction is completed, add acid to adjust the pH to neutral, and then concentrate and dry to obtain cationic starch; A3. add the cationic starch obtained in step A2 into the composite synergist component, stir uniformly to obtain a pre-reaction solution, then add microcrystalline wax and the pre-preparation prepared in step A1, mix uniformly, adjust the pH of the system to 4-5 with a 70% mass fraction phosphoric acid solution, add ethylene glycol diglycidyl ether, heat to 50℃, stir for 2 h, concentrate and dry to obtain the organic coated composite synergist component, wherein the composite synergist component is prepared from γ-polyglutamic acid, polyaspartic acid and inulin, and the mass ratio of the composite synergist component, the cationic starch and the pre-preparation is 100:1.8:1, and the mass ratio of the cationic starch, the microcrystalline wax and the ethylene glycol diglycidyl ether is 1:0.08:2; The preparation method of the composite synergist component in step A3 is as follows: 5 parts of γ-polyglutamic acid and 2 parts of polyaspartic acid are dissolved in 40 parts of a 1% mass fraction sodium alginate solution, then 0.8 parts of inulin is added, while stirring, 0.2 parts of acetic acid is added dropwise, after the dropwise addition is completed, stirring is carried out for 15 min to obtain the composite synergist component; The preparation of the modified diatomite in the raw material components comprises the following contents: B1. Prepare a citric acid solution with a mass concentration of 0.1 g / L, stir diatomite and the citric acid solution according to a mass ratio of 100:3.8, mix thoroughly, obtain mixed slurry, and dry the mixed slurry after standing to obtain pretreated diatomite; B2. Prepare a sodium polyacrylate solution with a mass concentration of 0.05 g / L, stir the pretreated diatomite and the sodium polyacrylate solution according to a mass ratio of 100:4, mix thoroughly, adjust the slurry to neutral, obtain modified mud slurry, dry the modified mud slurry after standing, and grind into 200-mesh powder to obtain modified diatomite.

[0026] Example 3: A fertilizer synergist prepared from the following raw material components: 10 parts of organic coated composite synergistic component, 30 parts of modified diatomite, 3 parts of wood ash, 0.4 parts of potassium sulfate, and 3 parts of water, and the specific preparation method comprises the following steps: S1. Mix the organic coated composite synergistic component and the modified diatomite uniformly, add half of the amount of water, stir for 8 min, and obtain a premix; S2. Mix the remaining other raw materials uniformly, then add the premix of step S1, heat to 60℃, stir for 10 min, concentrate and dry to obtain the fertilizer synergist.

[0027] The preparation of the organic coated composite synergistic component comprises the following steps: A1. Add lactic acid and ethylene glycol into a reactor according to a mass ratio of 1:2, control the pressure to be 6 kPa, heat to 130℃, stir for 0.5 h, then add terephthalic acid and concentrated sulfuric acid, the addition amount of terephthalic acid and concentrated sulfuric acid is 6% and 2.5% of the mass of lactic acid respectively, heat to 160℃, stir for 6 h, and then cool to room temperature to obtain a pre-preparation; A2. Dissolve starch in a mixed solution containing water and 1,4-dioxane, wherein the mass ratio of starch to the mixed solution is 1:3, and the mass ratio of water to 1,4-dioxane in the mixed solution is 1:1, then add sodium hydroxide to adjust the pH to 9-10, heat to 70℃ for gelatinization, add epoxypropyltrimethylammonium chloride for reaction for 2 h, the addition amount of epoxypropyltrimethylammonium chloride is 6% of the mass of starch, after the reaction is completed, add acid to adjust the pH to neutral, and then concentrate and dry to obtain cationic starch; A3. The cationic starch obtained in step A2 is added to the complex synergistic component, stirred to be uniform, to obtain a pre-reaction solution, then the microcrystalline wax and the preformed material prepared in step A1 are added and mixed uniformly, the pH value of the system is adjusted to 4-5 with a 80% phosphoric acid solution, the ethylene glycol diglycidyl ether is added, heated to 60°C, stirred to react for 1 h, concentrated and dried to obtain the organic coated complex synergistic component, wherein the complex synergistic component is prepared from γ-polyglutamic acid, polyaspartic acid and inulin, the mass ratio of the complex synergistic component, the cationic starch and the preformed material is 100:2.2:2, and the mass ratio of the cationic starch, the microcrystalline wax and the ethylene glycol diglycidyl ether is 1:0.12:4; The preparation method of the complex synergistic component in step A3 is as follows: 5 parts of γ-polyglutamic acid and 3 parts of polyaspartic acid are dissolved in 60 parts of a 2% sodium alginate solution by mass fraction, then 1.2 parts of inulin is added, 0.3 parts of acetic acid is added dropwise while stirring, and after the dropwise addition is completed, the mixture is stirred for 25 min to obtain the complex synergistic component; The preparation of the modified diatomite in the raw material component includes the following contents: B1. A citric acid solution with a mass concentration of 0.3 g / L is prepared, diatomite and the citric acid solution are stirred according to a mass ratio of 100:4.2, fully mixed, and the mixed slurry is obtained. After the mixed slurry is left to stand and dried, the pretreated diatomite is obtained. B2. A sodium polyacrylate solution with a mass concentration of 0.2 g / L is prepared, the pretreated diatomite and the sodium polyacrylate solution are stirred according to a mass ratio of 100:6, fully mixed, and the slurry is adjusted to neutral. The modified slurry is obtained. After the modified slurry is left to stand and dried, it is ground and crushed into a 200-mesh powder to obtain the modified diatomite.

[0028] Example 4: A fertilizer synergist is prepared from the following raw material components: 10 parts of an organic coated complex synergistic component, 20 parts of modified diatomite, 3 parts of wood ash, 0.2 parts of potassium sulfate and 3 parts of water. The specific preparation method includes the following steps: S1. The organic coated complex synergistic component and the modified diatomite are mixed uniformly, half of the amount of water is added, and stirred for 5 min to obtain a premix; S2. The remaining other raw materials are mixed uniformly, then added to the premix of step S1, heated to 50°C, stirred for 20 min, concentrated and dried to obtain the fertilizer synergist.

[0029] The preparation of the organic coated complex synergistic component includes the following steps: A1, lactic acid and ethylene glycol are added into a reactor according to a mass ratio of 1:2, the pressure is controlled at 4 kPa, heated to 130 DEG C, stirred for 1.5 h, then terephthalic acid and concentrated sulfuric acid are added, the addition amount of terephthalic acid and concentrated sulfuric acid is 4% and 2.5% of the mass of lactic acid respectively, heated to 140 DEG C, stirred for 10 h, and then cooled to room temperature to obtain a preformed material; A2, starch is dissolved in a mixed solution containing water and 1,4-dioxane, wherein the mass ratio of starch to mixed solution is 1:3, and the mass ratio of water to 1,4-dioxane in the mixed solution is 1:1, then sodium hydroxide is added to adjust the pH to 9-10, heated to 70 DEG C for gelatinization, and then propyltrimethylammonium chloride is added for reaction for 2 h, the addition amount of propyltrimethylammonium chloride is 4% of the mass of starch, after the reaction is completed, acid is added to adjust the pH to neutral, concentrated and dried to obtain cationic starch; A3, the cationic starch obtained in step A2 is added into a composite synergistic component, stirred uniformly to obtain a pre-reaction solution, then microcrystalline wax and the preformed material prepared in step A1 are added, mixed uniformly, the pH value of the system is adjusted to 4-5 by using a phosphoric acid solution with a mass fraction of 80%, heated to 50 DEG C, stirred and reacted for 2 h, concentrated and dried to obtain an organic coated composite synergistic component, wherein the composite synergistic component is prepared from gamma-polyglutamic acid, polyaspartic acid and inulin, and the mass ratio of the composite synergistic component, cationic starch and preformed material is 100:1.8:2, and the mass ratio of cationic starch, microcrystalline wax and ethylene glycol diglycidyl ether is 1:0.08:4; The preparation method of the composite synergistic component in step A3 is as follows: 5 parts of gamma-polyglutamic acid and 2 parts of polyaspartic acid are dissolved in 60 parts of a sodium alginate solution with a mass fraction of 1%, then 1.2 parts of inulin is added, 0.2 parts of acetic acid is added dropwise while stirring, and after the dropwise addition is completed, stirring is continued for 25 min to obtain the composite synergistic component; The preparation of the modified diatomite in the raw material component includes the following contents: B1. A citric acid solution with a mass concentration of 0.1 g / L is prepared, diatomite and the citric acid solution are stirred according to a mass ratio of 100:4.2, and fully mixed to obtain a mixed slurry, the mixed slurry is left to stand and then dried to obtain pretreated diatomite; B2. A sodium polyacrylate solution with a mass concentration of 0.05 g / L is prepared, the pretreated diatomite and the sodium polyacrylate solution are stirred according to a mass ratio of 100:6, fully mixed, and the slurry is adjusted to neutral to obtain modified slurry, the modified slurry is left to stand and then dried, ground and crushed into a 200-mesh powder to obtain modified diatomite.

[0030] Embodiment 5: a fertilizer synergist prepared from the following raw material components: 10 parts of an organic coated composite synergist component, 30 parts of modified diatomite, 1 part of wood ash, 0.4 part of potassium sulfate, and 2 parts of water, and the specific preparation method comprises the following steps: S1. uniformly mix the organic coated composite synergist component and the modified diatomite, add half of the amount of water, stir for 5 min, and obtain a premix; S2. uniformly mix the remaining other raw materials, then add the premix of step S1, heat to 60℃, stir for 10 min, concentrate, and dry to obtain the fertilizer synergist.

[0031] The preparation of the organic coated composite synergist component comprises the following steps: A1. add lactic acid and ethylene glycol in a mass ratio of 1:2 into a reactor, control the pressure to be 6 kPa, heat to 120℃, stir for 1 h, then add terephthalic acid and concentrated sulfuric acid, the addition amount of terephthalic acid and concentrated sulfuric acid is 6% and 1.5% of the mass of lactic acid respectively, heat to 160℃, stir for 6 h, and then cool to room temperature to obtain a pre-preparation; A2. dissolve the starch in a mixed solution containing water and 1,4-dioxane, wherein the mass ratio of starch to mixed solution is 1:3, and the mass ratio of water to 1,4-dioxane in the mixed solution is 1:1, then add sodium hydroxide to adjust the pH to 9-10, heat to 60℃ for gelatinization, add epoxypropyltrimethylammonium chloride for reaction for 2 h, the addition amount of epoxypropyltrimethylammonium chloride is 5% of the mass of starch, after the reaction is completed, add acid to adjust the pH to neutral, and then concentrate and dry to obtain cationic starch; A3. add the cationic starch obtained in step A2 into the composite synergist component, stir uniformly to obtain a pre-reaction solution, then add microcrystalline wax and the pre-preparation prepared in step A1, mix uniformly, adjust the pH of the system to 4-5 with a 80% mass fraction phosphoric acid solution, add ethylene glycol diglycidyl ether, heat to 60℃, stir for 1 h, concentrate and dry to obtain the organic coated composite synergist component, wherein the composite synergist component is prepared from γ-polyglutamic acid, polyaspartic acid and inulin, and the mass ratio of the composite synergist component, the cationic starch and the pre-preparation is 100:2.2:1.5, and the mass ratio of the cationic starch, the microcrystalline wax and the ethylene glycol diglycidyl ether is 1:0.1:2; The preparation method of the composite synergist component in step A3 is as follows: dissolve 5 parts of γ-polyglutamic acid and 3 parts of polyaspartic acid in 40 parts of a 2% mass fraction sodium alginate solution, then add 0.8 parts of inulin, add 0.3 parts of acetic acid dropwise while stirring, and after the dropwise addition is completed, stir for 15 min to obtain the composite synergist component; The preparation of the modified diatomite in the raw material components comprises the following contents: B1. A solution of citric acid with a mass concentration of 0.3 g / L is configured, diatomite and the solution of citric acid are stirred according to a mass ratio of 100:3.8, fully mixed, and the mixed slurry is obtained. After the mixed slurry is left to stand and dried, pretreated diatomite is obtained. B2. A solution of sodium polyacrylate with a mass concentration of 0.2 g / L is configured, pretreated diatomite and the solution of sodium polyacrylate are stirred according to a mass ratio of 100:4, fully mixed, and the slurry is adjusted to neutral. Modified mud slurry is obtained. After the modified mud slurry is left to stand and dried, it is ground and crushed into a 200-mesh powder to obtain modified diatomite.

[0032] Comparative Example 1: The difference between this comparative example and Example 1 is only that the raw material components of the fertilizer synergist do not have the organic coating of the composite synergistic component, i.e., the organic coating composite synergistic component is replaced by the composite synergistic component, which specifically includes the following raw material components: composite synergistic component 10 parts, modified diatomite 25 parts, wood ash 2 parts, potassium sulfate 0.3 parts, and water 2.5 parts.

[0033] Comparative Example 2: The difference between this comparative example and Example 1 is only that the raw material components of the fertilizer synergist do not have the modification of diatomite, i.e., the modified diatomite is replaced by diatomite, which specifically includes the following raw material components: organic coating composite synergistic component 10 parts, diatomite 25 parts, wood ash 2 parts, potassium sulfate 0.3 parts, and water 2.5 parts.

[0034] Comparative Example 3: The difference between this comparative example and Example 1 is only that the raw material components of the fertilizer synergist do not have the organic coating of the composite synergistic component and do not have the modification of diatomite, which specifically includes the following raw material components: composite synergistic component 10 parts, diatomite 25 parts, wood ash 2 parts, potassium sulfate 0.3 parts, and water 2.5 parts.

[0035] Effect proof: The fertilizer synergists prepared in Examples 1-5 and Comparative Examples 1-3 are mixed with compound fertilizer according to a mass ratio of 3:100, granulated to obtain synergistic fertilizer, and the synergistic fertilizer is applied to the test soil according to the conventional method. The test soil is a Cd-contaminated farmland soil, the soil is kept moist, small bok choy seeds with plump grains are selected, soaked in water and then sown, the sowing depth is 1±0.5 cm, the temperature, humidity and light are controlled, and the bok choy is harvested after 30 days of planting. The yield of each test group is calculated based on the blank group without adding the synergist, the yield increase rate is calculated, the yield increase rate=(test group yield-blank group yield) / blank group yield x 100%, and the Cd content of the bok choy plants in each test group is measured. The specific test results are shown in Table 1: Table 1 Yield increase (%) Cd content (mg / kg) Example 1 9.8 0.013 Example 2 9.6 0.016 Example 3 9.7 0.013 Example 4 9.4 0.015 Example 5 9.6 0.014 Example 1 7.0 0.041 Example 2 8.8 0.067 Example 3 6.2 0.079 Result analysis: analyzing examples 1-5 and comparative examples 1-3, and combining table 1 can see that the fertilizer synergist prepared by the present application is used in the synergistic fertilizer, compared with the blank group, the yield increase rate of examples 1-5 is more than 9.4%, and the Cd content of the plant is less than 0.016mg / kg, which shows that the fertilizer synergist provided by the present application can realize efficient utilization of fertilizer nutrients, improve crop yield, and effectively reduce the heavy metal content of the plant, and show excellent heavy metal remediation effect. The specific analysis is as follows: By comparing comparative example 1 with example 1, it can be seen that when the raw material component of the fertilizer synergist is not organically coated, the yield increase rate of the fertilizer synergist prepared is reduced from 9.8% to 7.0% when applied to the small cabbage, and the Cd content is increased from 0.013mg / kg to 0.041mg / kg, which shows that organically coating the composite synergistic component can improve crop yield and reduce the heavy metal content of the plant; By comparing comparative example 2 with example 1, it can be seen that when the raw material component of the fertilizer synergist is not modified, the yield increase rate of the fertilizer synergist prepared is reduced from 9.8% to 8.8% when used in the synergistic fertilizer, and the Cd content is increased from 0.013mg / kg to 0.067mg / kg, which shows that modifying the diatomite can improve crop yield and reduce the heavy metal content of the plant; By analyzing comparative examples 1-3 and example 1, it can be seen that organically coating the composite synergistic component and modifying the diatomite can both improve crop yield and reduce the heavy metal content of the plant, and when the two treatment methods are used together, the decrease amplitude of the Cd content of the small cabbage plant (the difference between comparative example 3 and example 1) of the fertilizer synergist prepared is obviously greater than the sum of the increase amplitudes when the two treatment methods are used alone (the difference between comparative example 3 and comparative example 1 and the sum of the difference between comparative example 3 and comparative example 2), which shows that in this system, the combination of organically coating the composite synergistic component and modifying the diatomite can produce a synergistic effect, which can greatly reduce the heavy metal content of the plant.

[0036] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combinations.

[0037] In addition, various different embodiments of the present application can also be combined in any manner, as long as they do not deviate from the idea of the present application, and they should also be considered as disclosed by the present application.

Claims

1. A fertilizer synergist, characterized in that, By weight, it includes the following raw material components: 10 parts of organic coating composite synergist, 20-30 parts of modified diatomaceous earth, 1-3 parts of wood ash, 0.2-0.4 parts of potassium sulfate and 2-3 parts of water, wherein the modified diatomaceous earth is obtained by modifying diatomaceous earth sequentially through citric acid solution and sodium polyacrylate solution.

2. The fertilizer synergist according to claim 1, characterized in that, The preparation of organic-coated composite synergistic components includes the following steps: A1. Add lactic acid and ethylene glycol to the reactor, control the pressure and temperature, stir evenly, then add terephthalic acid and concentrated sulfuric acid, heat to 140-160℃, stir for 6-10 hours, cool to room temperature to obtain the pre-made material for later use. A2. Dissolve starch in a mixed solution containing water and 1,4-dioxane, add sodium hydroxide to adjust the pH to 9-10, heat to 60-70℃ for gelatinization, then add glycidyltrimethylammonium chloride, react for 2-3 hours, add acid to adjust the pH to neutral after the reaction, concentrate and dry to obtain cationic starch. A3. Add the cationic starch obtained in step A2 to the composite synergist and stir evenly to obtain a pre-reaction solution. Then add microcrystalline wax and the pre-prepared material obtained in step A1 and stir evenly. Adjust the pH of the system to 4-5 with a 70-80% phosphoric acid solution. Add ethylene glycol diglycidyl ether and heat to 50-60℃. Stir and react for 1-2 hours. Concentrate and dry to obtain the organic-coated composite synergist, wherein the composite synergist is prepared from γ-polyglutamic acid, polyaspartic acid and inulin.

3. The fertilizer synergist according to claim 2, characterized in that, In step A1, the mass ratio of lactic acid to ethylene glycol is 1:2, and the amounts of terephthalic acid and concentrated sulfuric acid added are 4-6% and 1.5-2.5% of the mass of lactic acid, respectively.

4. The fertilizer synergist according to claim 2, characterized in that, In step A2, the mass ratio of starch to the mixed solution is 1:2-3, and the mass ratio of water to 1,4-dioxane in the mixed solution is 1:

1.

5. The fertilizer synergist according to claim 2, characterized in that, In step A3, the mass ratio of the compound synergist, cationic starch and pre-prepared material is 100:1.8-2.2:1-2, and the mass ratio of cationic starch, microcrystalline wax and ethylene glycol diglycidyl ether is 1:0.08-0.12:2-4.

6. The fertilizer synergist according to claim 2, characterized in that, The preparation method of the compound synergistic component in step A3 is as follows: by weight, 5 parts of γ-polyglutamic acid and 2-3 parts of polyaspartic acid are dissolved in 40-60 parts of sodium alginate solution with a mass fraction of 1-2%, then 0.8-1.2 parts of inulin are added, and 0.2-0.3 parts of acetic acid are added dropwise while stirring. After the addition is completed, the mixture is stirred for 15-25 minutes to obtain the compound synergistic component.

7. The fertilizer synergist according to claim 1, characterized in that, The preparation of modified diatomaceous earth includes the following: B1. Prepare a citric acid solution with a mass concentration of 0.1-0.3 g / L, stir the diatomaceous earth with the citric acid solution, mix thoroughly to obtain a mixed slurry, let the mixed slurry stand and then dry it to obtain pretreated diatomaceous earth; B2. Prepare a sodium polyacrylate solution with a mass concentration of 0.05-0.2 g / L. Stir the pretreated diatomaceous earth with the sodium polyacrylate solution. After thorough mixing, adjust the slurry to neutral to obtain modified mud. After the modified mud is allowed to stand, dry it and grind it to obtain modified diatomaceous earth.

8. The fertilizer synergist according to claim 7, characterized in that, In step B1, the mass ratio of diatomaceous earth to citric acid solution is 100:3.8-4.

2.

9. The fertilizer synergist according to claim 7, characterized in that, In step B2, the pretreated diatomaceous earth and sodium polyacrylate solution are mixed at a mass ratio of 100:4-6.

10. A method for preparing a fertilizer synergist, used to prepare the fertilizer synergist according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Mix the organic-coated composite synergistic component and modified diatomaceous earth evenly, add half the amount of water, stir for 3-8 minutes to obtain the premix; S2. Mix the remaining raw materials evenly, then add them to the premix prepared in step S1, heat to 50-60℃, stir for 10-20 minutes, concentrate and dry to obtain the fertilizer synergist.