A plant micronutrient complexing agent and its preparation method and application

Abstract

The present invention provides a plant micronutrient complexing agent, a preparation method and application thereof, and belongs to the technical field of plant nutrition synergism. The plant micronutrient complexing agent of the present invention includes a carboxylic acid amine or its salt complexing agent, an auxiliary complexing agent and a regulator; through the synergistic effect generated between the components, multiple micronutrients can be stably complexed at the same time, so that precipitation between the micronutrients does not occur and affect the fertilizer application effect; the regulator contained can effectively prevent the complexed micronutrient fertilizer from being mixed with nitrogen, phosphorus, potassium and other macronutrient fertilizers during application, thereby preventing water-insoluble matter from being generated and affecting the fertilizer effect. The complexing agent of the present invention has a stable complexing effect on plant micronutrients, and its properties are not easily deteriorated at temperature. At the same time, the production process is short and the production cost is low. The preparation process is green and environmentally friendly, and is very suitable for industrial expansion production.

Description

Technical Field

[0001] The present invention relates to the technical field of plant nutrition synergism, and in particular to a plant trace nutrient complexing agent, a preparation method and application thereof. Background Art

[0002] In addition to macronutrient fertilizers like nitrogen, phosphorus, and potassium, micronutrients required by plants, such as calcium, magnesium, iron, copper, manganese, zinc, molybdenum, boron, and sulfur, play a crucial role in balancing physiological activity. They regulate enzyme activity within plants and increase chlorophyll content, thereby enhancing photosynthesis. Therefore, appropriately applying micronutrient fertilizers alongside macronutrient fertilizers not only promotes the normal growth and development of crops, but also enhances their stress resistance, improves fertilizer utilization, and increases crop yields.

[0003] Since trace element fertilizers contain antagonism between elements during processing, their efficiency is greatly reduced. To maintain the stability of trace elements, the most effective method is to use a complexing agent to complex the trace elements and prepare a complexed trace element fertilizer. In the prior art, complexing agents mainly include disodium ethylenediaminetetraacetic acid, sodium ethylenediamine di-o-phenylacetate, and citric acid. However, these complexing agents also have the problems of being unable to complex multiple trace elements simultaneously and having a complex production process with high costs. Summary of the Invention

[0004] The present invention aims to provide a plant trace nutrient complexing agent and its preparation method and application. The plant trace nutrient complexing agent is efficient and stable, and solves the problems that the existing trace element complexing agents cannot complex multiple trace elements at the same time, and the production process is complicated and costly.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a plant micronutrient complexing agent, comprising a carboxylic acid amine or its salt complexing agent, an auxiliary complexing agent and a regulator;

[0007] The carboxylic acid amine or its salt complexing agent includes PADTA, ammonium citrate, potassium sodium tartrate and sodium alginate; the PADTA is a mixture of disodium ethylenediaminetetraacetic acid and disodium aminotriacetic acid;

[0008] The auxiliary complexing agent includes citric acid, sodium fumarate, sodium glycine and sodium borate;

[0009] The regulator includes sodium hexametaphosphate, sodium gluconate, sodium hydrogen phthalate and sodium polyacrylate;

[0010] The mass ratio of the carboxylic acid amine or its salt complexing agent, the auxiliary complexing agent and the regulator is (43-52):(17-26):(21-29).

[0011] Preferably, the mass ratio of PADTA, ammonium citrate, potassium sodium tartrate and sodium alginate is 36-42:5-8:2-5:2-4.

[0012] Preferably, the mass ratio of disodium edetate to disodium aminotriacetate is (1.5-3):1.

[0013] Preferably, the mass ratio of the citric acid, sodium fumarate, sodium glycinate and sodium borate is 6-10:3-6:4-6:6-9.

[0014] Preferably, the mass ratio of the sodium hexametaphosphate, sodium gluconate, sodium hydrogen phthalate and sodium polyacrylate is 7-12:3-6:5-9:4-8.

[0015] Preferably, the plant trace nutrient complexing agent is composed of the following components in parts by mass: 36-42 parts of PADTA, 2-5 parts of potassium sodium tartrate, 2-4 parts of sodium alginate, 7-12 parts of sodium hexametaphosphate, 5-8 parts of ammonium citrate, 6-10 parts of citric acid, 3-6 parts of sodium gluconate, 3-6 parts of sodium fumarate, 4-6 parts of sodium glycinate, 5-9 parts of sodium hydrogen phthalate, 6-9 parts of sodium borate, and 4-8 parts of sodium polyacrylate, and the total part by mass of all components is 100 parts.

[0016] The present invention provides a method for preparing the plant trace nutrient complexing agent described in the above technical solution, comprising the following steps:

[0017] Mixing part of the regulator with a carboxylic acid amine or a salt thereof as a complexing agent to obtain a first mixture, and mixing the remaining regulator with an auxiliary complexing agent to obtain a second mixture;

[0018] The first mixture and the second mixture are mixed to obtain a plant micronutrient complexing agent.

[0019] Preferably, the mass of the partial regulator accounts for 20 to 40% of the total mass of the regulator.

[0020] The present invention provides the use of the plant trace nutrient complexing agent described in the above technical solution or the plant trace nutrient complexing agent prepared by the preparation method described in the above technical solution in trace element fertilizers.

[0021] In the plant trace nutrient complexing agent provided by the present invention, the carboxylic acid amine or its salt complexing agent has multiple coordination spaces and has strong complexing ability for metal ions, but its stability is limited by the pH range. By adding a regulator and an auxiliary complexing agent, the stability of the complexing agent can be improved and the pH limit range can be expanded. The regulator can adjust the local pH within a certain range to play a buffering role, so that the complexing agent first reacts with the ions to form a stable complex, rather than directly forming an irreversible precipitation process. The auxiliary complexing agent reacts with the complexing agent in advance under certain conditions to increase or weaken its complexing sites, so that the complexing agent can stably complex the trace element ions required by various plants. Specifically, by adding ammonium citrate, sodium fumarate and sodium borate, not only can the complexing ability of the complexing agent for trace nutrient metal elements be increased, but it can also form a stable interaction with the trace nutrient non-metallic elements, thereby jointly improving the stability of the complexes of each trace nutrient element; by using sodium hexametaphosphate, sodium hydrogen phthalate and sodium polyacrylate as regulators and acting together with PADTA, it can effectively prevent the irreversible precipitation reaction formed by local pH unevenness during the complexing process of trace nutrients, prolong the action time of the complexing agent and the trace nutrients, and thus improve the complex stability.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The plant micronutrient complexing agent of the present invention can simultaneously and stably complex multiple micronutrients through the synergistic effect generated between the components, so that the micronutrients do not precipitate and affect the fertilizer application effect;

[0024] (2) The plant micronutrient complexing agent of the present invention contains a regulator, which can effectively prevent the production of water-insoluble substances during the mixed application of complexed micronutrient fertilizers with fertilizers containing nitrogen, phosphorus, potassium and other macronutrients, thereby affecting the fertilizer efficiency;

[0025] (3) The present invention uses a specific preparation process and process, specific formula components, and the formula and method work together to produce a complexing agent that has a stable complexing effect on plant trace nutrients and is not easily deteriorated at temperature. At the same time, the production process is short and the production cost is low. The preparation process is green and environmentally friendly, and is very suitable for industrial expansion production.

[0026] (4) During the preparation of the plant micronutrient complexing agent described in the present invention, synergistic effects can be generated between the various components. The resulting complexing agent forms a stable complex with the micronutrients required by plants. After the stable complex is dissolved in water, no precipitation occurs within a certain pH range. Instead, the stable complex exists as a stable complex ion formed by the complexing agent and ions. Therefore, the problem of precipitation between metal ions and hydroxide in the aqueous solution does not occur. The complexing agent can effectively complex a variety of metal element ions so that their aqueous solutions do not produce precipitation. At the same time, the solution can also be mixed with other macronutrient fertilizers to remain stable within a wider pH range, preventing the formation of acid-insoluble substances between the various nutrient elements and affecting plant absorption. DETAILED DESCRIPTION

[0027] The present invention provides a plant micronutrient complexing agent, comprising a carboxylic acid amine or its salt complexing agent, an auxiliary complexing agent and a regulator;

[0028] The carboxylic acid amine or its salt complexing agent includes PADTA, ammonium citrate, potassium sodium tartrate and sodium alginate; the PADTA is a mixture of disodium ethylenediaminetetraacetic acid and disodium aminotriacetic acid;

[0029] The auxiliary complexing agent includes citric acid, sodium fumarate, sodium glycine and sodium borate;

[0030] The regulator includes sodium hexametaphosphate, sodium gluconate, sodium hydrogen phthalate and sodium polyacrylate;

[0031] The mass ratio of the carboxylic acid amine or its salt complexing agent, the auxiliary complexing agent and the regulator is (43-52):(17-26):(21-29).

[0032] Unless otherwise specified, the components used in the present invention are all commercially available products well known in the art.

[0033] The plant micronutrient complexing agent provided by the present invention comprises a carboxylic acid amine or a salt thereof; the carboxylic acid amine or a salt thereof comprises PADTA, ammonium citrate, potassium sodium tartrate and sodium alginate; and the PADTA is a mixture of disodium ethylenediaminetetraacetic acid and disodium aminotriacetic acid.

[0034] In the present invention, the mass ratio of PADTA, ammonium citrate, potassium sodium tartrate and sodium alginate is preferably 36-42:5-8:2-5:2-4, more preferably 38-40:6-7:2-3:2-3.

[0035] In the present invention, the mass ratio of disodium edetate to disodium aminotriacetate is preferably (1.5-3):1, more preferably 2-2.5:1.

[0036] The plant micronutrient complexing agent provided by the invention comprises an auxiliary complexing agent; the auxiliary complexing agent comprises citric acid, sodium fumarate, sodium glycine and sodium borate.

[0037] In the present invention, the mass ratio of citric acid, sodium fumarate, sodium glycinate and sodium borate is preferably 6-10:3-6:4-6:6-9, more preferably 7-8:4-5:5-6:7-8.

[0038] The plant micronutrient complexing agent provided by the invention comprises a regulator; the regulator comprises sodium hexametaphosphate, sodium gluconate, sodium hydrogen phthalate and sodium polyacrylate.

[0039] In the present invention, the mass ratio of the sodium hexametaphosphate, sodium gluconate, sodium hydrogen phthalate and sodium polyacrylate is preferably 7-12:3-6:5-9:4-8, more preferably 8-10:4-5:6-8:5-6.

[0040] In the present invention, the mass ratio of the carboxylic acid amine or its salt complexing agent, the auxiliary complexing agent and the regulator is (43-52):(17-26):(21-29), preferably (45-52):(18-24):(22-28), and more preferably (49-51):(22-23):(26-27).

[0041] In the present invention, the plant trace nutrient complexing agent is preferably composed of the following components in parts by mass: 36-42 parts of PADTA, 2-5 parts of potassium sodium tartrate, 2-4 parts of sodium alginate, 7-12 parts of sodium hexametaphosphate, 5-8 parts of ammonium citrate, 6-10 parts of citric acid, 3-6 parts of sodium gluconate, 3-6 parts of sodium fumarate, 4-6 parts of sodium glycinate, 5-9 parts of sodium hydrogen phthalate, 6-9 parts of sodium borate, and 4-8 parts of sodium polyacrylate, and the total part by mass of all components is 100 parts; more preferably, 40 parts of PADTA, 3 parts of potassium sodium tartrate, 2 parts of sodium alginate, 8 parts of sodium hexametaphosphate, 6 parts of ammonium citrate, 8 parts of citric acid, 4 parts of sodium gluconate, 5 parts of sodium fumarate, 5 parts of sodium glycinate, 6 parts of sodium hydrogen phthalate, 8 parts of sodium borate, and 5 parts of sodium polyacrylate, and the total part by mass is 100 parts.

[0042] The present invention provides a method for preparing the plant trace nutrient complexing agent described in the above technical solution, comprising the following steps:

[0043] Mixing part of the regulator with a carboxylic acid amine or a salt thereof as a complexing agent to obtain a first mixture, and mixing the remaining regulator with an auxiliary complexing agent to obtain a second mixture;

[0044] The first mixture and the second mixture are mixed to obtain a plant micronutrient complexing agent.

[0045] In the present invention, the mass of the partial regulator accounts for 50 to 80% of the total mass of the regulator, and more preferably 60 to 70%.

[0046] In the present invention, the preparation method of the carboxylic acid amine or its salt complexing agent is preferably as follows: PADTA, ammonium citrate, potassium sodium tartrate and sodium alginate are added to a high-speed mixer and mixed for 5 to 10 minutes to obtain the carboxylic acid amine or its salt complexing agent; the stirring speed of the high-speed mixer is preferably 200 to 400 rpm, more preferably 300 rpm.

[0047] In the present invention, the preparation method of the auxiliary complexing agent is preferably: adding citric acid, sodium fumarate, sodium glycinate and sodium borate into a high-speed mixer with elevated temperature, mixing for 5 to 10 minutes to obtain the auxiliary complexing agent; the temperature of the high-speed mixer is preferably 25 to 50°C.

[0048] In the present invention, the preparation method of the regulator is preferably: adding sodium hexametaphosphate, sodium gluconate, sodium hydrogen phthalate and sodium polyacrylate into a high-speed mixer and mixing for 5 to 10 minutes to obtain the regulator; the stirring speed of the high-speed mixer is preferably 200 to 400 rpm.

[0049] In the present invention, the mixing temperature of the part of the regulator and the carboxylic acid amine or its salt complexing agent, the mixing of the remaining regulator and the auxiliary complexing agent, and the mixing of the first mixture and the second mixture are independently preferably 25-50° C., and the stirring speed is independently preferably 200-400 rpm.

[0050] The present invention provides the use of the plant micronutrient complexing agent described in the above technical solution or the plant micronutrient complexing agent prepared by the preparation method described in the above technical solution in trace element fertilizers. The present invention applies the plant micronutrient complexing agent to the stable complexation of plant micronutrients.

[0051] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0052] In the following examples and comparative examples, PADTA is a mixture of disodium edetate and disodium aminotriacetate, and the mass ratio of disodium edetate to disodium aminotriacetate is 2:1.

[0053] Example 1

[0054] The complexing agent of this embodiment includes the following components in parts by mass: 40 parts of PADTA, 3 parts of potassium sodium tartrate, 2 parts of sodium alginate, 6 parts of ammonium citrate, 8 parts of sodium hexametaphosphate, 4 parts of sodium gluconate, 6 parts of sodium hydrogen phthalate, 5 parts of sodium polyacrylate, 8 parts of citric acid, 5 parts of sodium fumarate, 5 parts of sodium glycinate, and 8 parts of sodium borate, with a total mass of 100 parts.

[0055] The preparation method comprises the following steps:

[0056] (1) PADTA, ammonium citrate, potassium sodium tartrate, and sodium alginate were added to a high-speed mixer and mixed for 10 minutes at a stirring speed of 300 rpm to obtain a mixture A;

[0057] (2) adding citric acid, sodium fumarate, sodium glycinate, and sodium borate into a high-speed mixer and mixing for 10 minutes at a stirring speed of 300 rpm to obtain a mixture B;

[0058] (3) Sodium hexametaphosphate, sodium gluconate, sodium hydrogen phthalate, and sodium polyacrylate were added to a high-speed mixer and mixed for 10 minutes at a stirring speed of 300 rpm to obtain a mixture C;

[0059] (4) At 50°C, mixture C was divided into two parts. 70% of mixture C was added to mixture A and mixed in a high-speed mixer at a stirring speed of 300 rpm for 10 min to obtain mixture AC. The remaining 30% of mixture C was added to mixture B and mixed in a high-speed mixer at a stirring speed of 300 rpm for 10 min to obtain mixture BC.

[0060] (5) Mixture AC and mixture BC were mixed in a high-speed mixer at 50° C. for 10 min at a stirring speed of 300 rpm to obtain a plant micronutrient complexing agent.

[0061] Example 2

[0062] Compared with Example 1, the only difference is that the plant trace nutrient complexing agent of this embodiment comprises the following components in parts by mass: 36 parts of PADTA, 3 parts of potassium sodium tartrate, 3 parts of sodium alginate, 7 parts of ammonium citrate, 8 parts of sodium hexametaphosphate, 4 parts of sodium gluconate, 6 parts of sodium hydrogen phthalate, 6 parts of sodium polyacrylate, 8 parts of citric acid, 6 parts of sodium fumarate, 5 parts of sodium glycinate, and 8 parts of sodium borate, with a total mass of 100 parts.

[0063] Example 3

[0064] Compared with Example 1, the only difference is that the plant trace nutrient complexing agent of this embodiment includes the following components in parts by mass: 42 parts of PADTA, 2 parts of potassium sodium tartrate, 2 parts of sodium alginate, 6 parts of ammonium citrate, 7 parts of sodium hexametaphosphate, 4 parts of sodium gluconate, 6 parts of sodium hydrogen phthalate, 5 parts of sodium polyacrylate, 8 parts of citric acid, 5 parts of sodium fumarate, 5 parts of sodium glycinate, and 8 parts of sodium borate, with a total mass of 100 parts.

[0065] Comparative Example 1

[0066] Compared with Example 1, the only difference is that in step (4), mixture A and mixture B are directly mixed and then added to mixture C to obtain the complexing agent.

[0067] Comparative Example 2

[0068] Compared with Example 1, the only difference is that the complexing agent in this comparative example includes the following components in parts by mass: 41 parts of PADTA, 4 parts of potassium sodium tartrate, 3 parts of sodium alginate, 9 parts of sodium hexametaphosphate, 7 parts of ammonium citrate, 0 parts of citric acid, 5 parts of sodium gluconate, 5 parts of sodium fumarate, 5 parts of sodium glycinate, 7 parts of sodium hydrogen phthalate, 8 parts of sodium borate, and 6 parts of sodium polyacrylate, with a total mass of 100 parts.

[0069] Comparative Example 3

[0070] Compared with Example 1, the only difference is that the complexing agent in this comparative example includes the following components in parts by mass: 41 parts of PADTA, 4 parts of potassium sodium tartrate, 3 parts of sodium alginate, 9 parts of sodium hexametaphosphate, 7 parts of ammonium citrate, 8 parts of citric acid, 5 parts of sodium gluconate, 5 parts of sodium fumarate, 5 parts of sodium glycinate, 7 parts of sodium hydrogen phthalate, 0 parts of sodium borate, and 6 parts of sodium polyacrylate, with a total mass of 100 parts.

[0071] Comparative Example 4

[0072] Compared with Example 1, the only difference is that the complexing agent in this comparative example includes the following components in parts by mass: 41 parts of PADTA, 4 parts of potassium sodium tartrate, 3 parts of sodium alginate, 9 parts of sodium hexametaphosphate, 7 parts of ammonium citrate, 8 parts of citric acid, 5 parts of sodium gluconate, 1 part of sodium fumarate, 1 part of sodium glycinate, 7 parts of sodium hydrogen phthalate, 8 parts of sodium borate, and 6 parts of sodium polyacrylate, with a total mass of 100 parts.

[0073] Comparative Example 5

[0074] Compared with Example 1, the only difference is that the complexing agent in this comparative example includes the following components in parts by mass: 45 parts of PADTA, 4 parts of potassium sodium tartrate, 4 parts of sodium alginate, 9 parts of sodium hexametaphosphate, 9 parts of ammonium citrate, 2 parts of citric acid, 5 parts of sodium gluconate, 2 parts of sodium fumarate, 2 parts of sodium glycinate, 8 parts of sodium hydrogen phthalate, 3 parts of sodium borate, and 7 parts of sodium polyacrylate, with a total mass of 100 parts.

[0075] Comparative Example 6

[0076] Compared with Example 1, the only difference is that the complexing agent in this comparative example includes the following components in parts by mass: 42 parts of PADTA, 3 parts of potassium sodium tartrate, 3 parts of sodium alginate, 0 parts of sodium hexametaphosphate, 8 parts of ammonium citrate, 9 parts of citric acid, 4 parts of sodium gluconate, 6 parts of sodium fumarate, 6 parts of sodium glycinate, 6 parts of sodium hydrogen phthalate, 8 parts of sodium borate, and 5 parts of sodium polyacrylate, with a total mass of 100 parts.

[0077] Comparative Example 7

[0078] Compared with Example 1, the only difference is that the complexing agent in this comparative example includes the following components in parts by mass: 41 parts of PADTA, 3 parts of potassium sodium tartrate, 2 parts of sodium alginate, 8 parts of sodium hexametaphosphate, 7 parts of ammonium citrate, 9 parts of citric acid, 4 parts of sodium gluconate, 6 parts of sodium fumarate, 6 parts of sodium glycinate, 6 parts of sodium hydrogen phthalate, 8 parts of sodium borate, and 0 part of sodium polyacrylate, and the total mass is 100 parts.

[0079] Comparative Example 8

[0080] Compared with Example 1, the only difference is that the complexing agent in this comparative example includes the following components in parts by mass: 42 parts of PADTA, 3 parts of potassium sodium tartrate, 3 parts of sodium alginate, 8 parts of sodium hexametaphosphate, 8 parts of ammonium citrate, 9 parts of citric acid, 2 parts of sodium gluconate, 6 parts of sodium fumarate, 6 parts of sodium glycinate, 2 parts of sodium hydrogen phthalate, 9 parts of sodium borate, and 2 parts of sodium polyacrylate, with a total mass of 100 parts.

[0081] Comparative Example 9

[0082] Compared with Example 2, the only difference is that the plant trace nutrient complexing agent in this comparative example comprises the following components in parts by mass: 39 parts of PADTA, 5 parts of potassium sodium tartrate, 5 parts of sodium alginate, 8 parts of sodium hexametaphosphate, 0 parts of ammonium citrate, 8 parts of citric acid, 4 parts of sodium gluconate, 6 parts of sodium fumarate, 5 parts of sodium glycinate, 6 parts of sodium hydrogen phthalate, 8 parts of sodium borate, and 6 parts of sodium polyacrylate, with a total mass of 100 parts.

[0083] Comparative Example 10

[0084] Compared with Example 2, the only difference is that the plant trace nutrient complexing agent in this comparative example includes the following components in parts by mass: 37 parts of PADTA, 0 parts of potassium sodium tartrate, 4 parts of sodium alginate, 8 parts of sodium hexametaphosphate, 8 parts of ammonium citrate, 8 parts of citric acid, 4 parts of sodium gluconate, 6 parts of sodium fumarate, 5 parts of sodium glycinate, 6 parts of sodium hydrogen phthalate, 8 parts of sodium borate, and 6 parts of sodium polyacrylate, with a total mass of 100 parts.

[0085] Comparative Example 11

[0086] Compared with Example 3, the only difference is that the plant trace nutrient complexing agent of this comparative example comprises the following components in parts by mass: 42 parts of PADTA, 0 parts of potassium sodium tartrate, 0 parts of sodium alginate, 7 parts of sodium hexametaphosphate, 10 parts of ammonium citrate, 8 parts of citric acid, 4 parts of sodium gluconate, 5 parts of sodium fumarate, 5 parts of sodium glycinate, 6 parts of sodium hydrogen phthalate, 8 parts of sodium borate, and 5 parts of sodium polyacrylate, with a total mass of 100 parts.

[0087] Performance Testing

[0088] The complexing agents prepared in Examples 1 to 3 and Comparative Examples 1 to 11 were subjected to performance tests:

[0089] (1) Stability of the complexing agent: Leave the complexing agent open at room temperature for 10 days and observe whether the complexing agent absorbs moisture, clumps, or deteriorates.

[0090] (2) Test of the complexing performance of plant trace nutrients: According to the mass of a certain metal salt being 10% of the mass of the complexing agent, a single metal salt (salt of Ca, Mg, Zn, Mn, Cu, Fe or Mo; specifically: calcium nitrate tetrahydrate, magnesium nitrate hexahydrate, iron nitrate nonahydrate, manganese nitrate hexahydrate, zinc nitrate heptahydrate, copper nitrate pentahydrate, sodium molybdate dihydrate) is added to the complexing agent for complexation in aqueous solution to observe whether there is precipitation.

[0091] (3) Complexation stability test of plant trace nutrients: According to the mass of a certain metal salt being 10% of the mass of the complexing agent, metal salts (salts of Ca, Mg, Zn, Mn, Cu, Fe or Mo, specifically: calcium nitrate tetrahydrate, magnesium nitrate hexahydrate, iron nitrate nonahydrate, manganese nitrate hexahydrate, zinc nitrate heptahydrate, copper nitrate pentahydrate, sodium molybdate dihydrate) are added to the complexing agent in aqueous solution for complexation, and ammonia water (mass concentration of 10%) or nitric acid aqueous solution (nitric acid mass concentration of 10%) is added to adjust the pH value. Among them, ammonia water is used to adjust the pH from 7 to 10, and nitric acid aqueous solution is added to adjust the pH from 7 to 4. The highest and lowest pH value ranges for precipitation of the complex are determined.

[0092] (4) Test of the complexing ability of plant trace nutrients: The mass of a certain metal salt is 10% of the mass of the complexing agent. Salts of Ca, Mg, Zn, Mn, Cu, Fe or Mo (specifically: calcium nitrate tetrahydrate, magnesium nitrate hexahydrate, iron nitrate nonahydrate, manganese nitrate hexahydrate, zinc nitrate heptahydrate, copper nitrate pentahydrate, sodium molybdate dihydrate) are added to the complexing agent respectively, and complexation is carried out in aqueous solution. The solution is concentrated and crystallized to obtain a solid. The mass proportion of the trace nutrients complexed by the complexing agent is determined by the ICP method.

[0093] The above test results are shown in Table 1.

[0094] Table 1 Performance data of complexing agents prepared in Examples 1 to 3 and Comparative Examples 1 to 11

[0095]

[0096]

[0097] The results in Table 1 show that, compared with Comparative Examples 1 to 8, the complexing agents prepared in Examples 1 to 3 of the present invention have the ability to stably complex plant trace nutrients within a wider pH range.

[0098] Compared with Example 1, in Comparative Example 1, mixture A and mixture B were directly mixed with mixture C. Due to the uneven distribution of the regulator in the complexing agent, local unevenness and agglomeration occurred, which ultimately affected the complexing performance.

[0099] Compared with Example 1, Comparative Examples 2 and 3 lack citric acid and sodium borate, respectively, and the resulting complexing agents are unstable in complexing trace nutrients, especially calcium, magnesium, and zinc ions.

[0100] Compared with Example 1, Comparative Example 4 reduces the ratio of the auxiliary complexing agents sodium fumarate and sodium glycinate, and the resulting complexing agent is unstable in complexing trace nutrients, and the complexing ability is reduced.

[0101] Compared with Example 1, Comparative Example 5 reduces the proportion of auxiliary complexing agents citric acid, sodium borate, sodium fumarate and sodium glycinate, and the resulting complexing agent is unstable in complexing trace nutrients and has a reduced complexing ability.

[0102] Compared with Example 1, Comparative Examples 6 and 7 lack the regulating agents sodium hexametaphosphate and sodium polyacrylate, respectively. The resulting complexing agents have reduced stability, are prone to moisture absorption and agglomeration, and their complexing ability is also affected.

[0103] Compared with Example 1, Comparative Example 8 reduced the amount of the regulating agents sodium gluconate, sodium hydrogen phthalate, and sodium polyacrylate, and the resulting complexing agent had reduced stability, was prone to moisture absorption and agglomeration, and also had affected its complexing ability.

[0104] Compared with Example 2, Comparative Example 9 lacks the complexing agent ammonium citrate, and the complexing ability of the obtained complexing agent is reduced, especially the complexing ability for copper and iron ions.

[0105] Compared with Example 2, Comparative Example 10 lacks the complexing agent potassium sodium tartrate, and the complexing ability of the obtained complexing agent is slightly reduced.

[0106] Compared with Example 3, Comparative Example 11 lacks the complexing agents potassium sodium tartrate and sodium alginate, and the complexing ability of the obtained complexing agent for calcium and magnesium ions is only slightly reduced.

[0107] (5) Test on the ability of plant trace nutrients to simultaneously complex multiple metals: The total mass of the seven metal salts is 10% of the mass of the complexing agent. Salts of Ca (1%), Mg (1%), Zn (2%), Mn (1%), Cu (2%), Fe (2%) and Mo (1%) (specifically: calcium nitrate tetrahydrate, magnesium nitrate hexahydrate, iron nitrate nonahydrate, manganese nitrate hexahydrate, zinc nitrate heptahydrate, copper nitrate pentahydrate, sodium molybdate dihydrate) are added to the complexing agent and complexed in aqueous solution. The solution is concentrated, crystallized and separated to obtain a solid. The mass proportion of the trace nutrients complexed by the complexing agent is determined by the ICP method.

[0108] The test results are shown in Table 2.

[0109] Table 2 Test data of the ability of complexing multiple metals prepared by the complexing agents of Examples 1 to 3 and Comparative Examples 1 to 3

[0110]

[0111] The results in Table 2 show that the complexing agents prepared in Examples 1 to 3 of the present invention have complexing capabilities for multiple metal ions. Compared with Examples 1 to 3, the complexing agents in Comparative Examples 1 to 3 have significantly decreased capabilities for complexing multiple metal ions simultaneously.

[0112] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A plant micronutrient complexing agent, characterized in that: Including carboxylic acid amine or its salt complexing agent, auxiliary complexing agent and regulator; The carboxylic acid amine or its salt complexing agent includes PADTA, ammonium citrate, potassium sodium tartrate and sodium alginate; the PADTA is a mixture of disodium ethylenediaminetetraacetic acid and disodium aminotriacetic acid; the mass ratio of the disodium ethylenediaminetetraacetic acid and disodium aminotriacetic acid is (1.5-3):1; The mass ratio of PADTA, ammonium citrate, potassium sodium tartrate and sodium alginate is 36-42:5-8:2-5:2-4; The auxiliary complexing agent includes citric acid, sodium fumarate, sodium glycine and sodium borate; the mass ratio of citric acid, sodium fumarate, sodium glycine and sodium borate is 6-10:3-6:4-6:6-9; The regulator includes sodium hexametaphosphate, sodium gluconate, sodium hydrogen phthalate and sodium polyacrylate; the mass ratio of sodium hexametaphosphate, sodium gluconate, sodium hydrogen phthalate and sodium polyacrylate is 7-12:3-6:5-9:4-8; The mass ratio of the carboxylic acid amine or its salt complexing agent, the auxiliary complexing agent and the regulator is (43-52): (17-26): (21-29); The preparation method of the plant trace nutrient complexing agent comprises the following steps: Mixing part of the regulator with a carboxylic acid amine or a salt thereof as a complexing agent to obtain a first mixture, and mixing the remaining regulator with an auxiliary complexing agent to obtain a second mixture; The first mixture and the second mixture are mixed to obtain a plant micronutrient complexing agent.

2. The plant micronutrient complexing agent according to claim 1, characterized in that The plant trace nutrient complexing agent is composed of the following components in parts by mass: 36-42 parts of PADTA, 2-5 parts of potassium sodium tartrate, 2-4 parts of sodium alginate, 7-12 parts of sodium hexametaphosphate, 5-8 parts of ammonium citrate, 6-10 parts of citric acid, 3-6 parts of sodium gluconate, 3-6 parts of sodium fumarate, 4-6 parts of sodium glycinate, 5-9 parts of sodium hydrogen phthalate, 6-9 parts of sodium borate, and 4-8 parts of sodium polyacrylate, and the total part by mass of all the components is 100 parts.

3. The method for preparing the plant micronutrient complexing agent according to any one of claims 1 to 2, characterized in that: The following steps are involved: Mixing part of the regulator with a carboxylic acid amine or a salt thereof as a complexing agent to obtain a first mixture, and mixing the remaining regulator with an auxiliary complexing agent to obtain a second mixture; The first mixture and the second mixture are mixed to obtain a plant micronutrient complexing agent.

4. The preparation method according to claim 3, characterized in that The mass of the partial regulator accounts for 20 to 40% of the total mass of the regulator.

5. Use of the plant trace nutrient complexing agent according to any one of claims 1 to 2 or the plant trace nutrient complexing agent prepared by the preparation method according to claim 3 or 4 in trace element fertilizers.

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