Environmentally friendly chelated element compound fertilizer and preparation method thereof

Abstract

The present invention belongs to the field of fertilizer technology, and specifically, relates to an environmentally friendly chelated element composite fertilizer and a preparation method thereof. The composite fertilizer is a chelated substance, or a chelated substance is added to a basic fertilizer; wherein the chelated substance is a substance obtained by a mixed reaction of a chelating agent and a metal salt, and the molar ratio between the chelating agent and the metal salt is between 1:0.97-1:0.30. The production process of the present invention is simple, the production process is relatively safe, no solid or liquid waste is generated during the production process, and other nutrient elements can be appropriately added according to actual needs to form a composite fertilizer containing large, medium and trace elements.

Description

Technical Field

[0001] The invention belongs to the technical field of fertilizers, and in particular relates to an environmentally friendly chelated element compound fertilizer and a preparation method thereof. Background Art

[0002] Adding trace elements to phosphorus-containing fertilizers has always been a headache, because general metal salts will react with phosphate to form insoluble or even insoluble substances. Therefore, when adding metal trace elements to phosphorus-containing fertilizers, they are added in the form of metal salt chelates. At present, EDTA-chelated metal salts are used to supplement trace elements in phosphorus-containing fertilizers in agricultural production, because other forms of chelated metal ions are prone to dissociation in systems containing phosphate, resulting in insoluble precipitates, which affects the nutritional effect of trace elements.

[0003] Adding trace elements of EDTA chelated titanium to fertilizers containing phosphorus can effectively solve the problem of metal ions reacting with phosphate to produce insoluble substances, reducing the effect of metal ions. Due to the large molecular weight of EDTA, the content of metal ions in EDTA chelated metal salts is relatively low, generally only about 15%. Increasing the content of metal ions in phosphorus-containing fertilizers without reducing the nutritional effect of metal elements will take up a lot of space and affect the improvement of fertilizer nutrient content.

[0004] When the pH is greater than 8.0, EDTA can be biodegraded in the environment, but when the environmental pH is less than 7.0, it cannot be biodegraded. About 2.5 billion hm2 of cultivated land and potential cultivated land in the world belong to acidic soil (<pH5.5), accounting for about 50% of the total area of ​​cultivated land and potential cultivated land. The area of ​​acidic soil in my country accounts for about 22.7% of the total land area of ​​the country. If the original acidic soil area plus the land that has been acidified later is calculated by cultivated land, the proportion of the total cultivated land area will be even greater. For these acidic soils, EDTA that enters the soil environment with fertilizer application will not be biodegraded for a long period of time. In this way, the long-term application of trace elements in the form of EDTA chelates will cause the accumulation of EDTA in the soil, which will have an adverse effect on the farmland environment and affect the original ecological environment of basic farmland and the sustainable development of soil. Summary of the invention

[0005] Aiming at the problem that long-term application of ethylenediaminetetraacetic acid chelated trace element fertilizer will lead to large accumulation of ethylenediaminetetraacetic acid in the soil, easily causing farmland soil environmental pollution and affecting soil sustainable development, the present invention further proposes an environmentally friendly chelated element compound fertilizer and a preparation method thereof.

[0006] To achieve the above purpose, the present invention adopts the following technical solution:

[0007] An environmentally friendly chelated element compound fertilizer, the compound fertilizer is a chelated substance, or a chelated substance is added to a basic fertilizer; wherein the chelated substance is a substance obtained by a mixed reaction of a chelating agent and a metal salt, and the molar ratio between the chelating agent and the metal salt is between 1:0.97 and 1:0.30.

[0008] The chelating substance is added to the basic fertilizer, and the amount of the chelating substance added accounts for 10%-70% of the mass of the basic fertilizer; wherein the basic fertilizer is nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer or common nitrogen-phosphorus-potassium compound fertilizer.

[0009] The chelating substance is a chelating agent which is dissolved in water and heated and stirred at 30-60°C. After it is completely dissolved, the pH value of the solution system is adjusted to 2-5, and then the metal salt is added. The original system temperature is maintained and stirred for 20-60 minutes to allow it to fully react.

[0010] The pH value of the dissolving liquid system can be adjusted by using ammonia water or potassium hydroxide.

[0011] One or more of the aminotri(methylene)phosphonic acid (ATMP), diethylenetriaminepentamethylenephosphonic acid (DETPMP), 2-hydroxyphosphonoacetic acid (HPAA), hydroxyethylidenediphosphonic acid (HEDP), and hexamethylenediaminetetramethylenephosphonic acid (HDTMP) can be used. When the chelating agents are mixed, the dosage of different chelating agents can be arbitrarily combined according to the formulation requirements, and the chelating effect of the chelated elements is not affected.

[0012] The metal salt is one or more of metal sulfate, nitrate and chloride; the metal is one or more of iron, manganese, copper and zinc.

[0013] A method for biologically preparing an environmentally friendly chelated element compound fertilizer, wherein the compound fertilizer is a chelated substance, or a chelated substance is added to a basic fertilizer; wherein the chelated substance is a substance obtained by a mixed reaction of a chelating agent and a metal salt, and the molar ratio between the chelating agent and the metal salt is between 1:0.97 and 1:0.30.

[0014] The compound fertilizer is a chelating agent dissolved in water and heated and stirred at 30-60°C. After it is completely dissolved, the pH value of the solution system is adjusted to 2-5, and then a metal salt is added. The original system temperature is maintained and stirred for 20-60 minutes to allow it to fully react, so as to obtain a chelating substance as a compound fertilizer.

[0015] The compound fertilizer is prepared by controlling the system temperature at 40-60 degrees Celsius after the chelating substance system is reacted and the solution is clarified, adding various materials of the basic fertilizer under stirring conditions to completely dissolve, then stopping heating and adjusting the volume to obtain a liquid fertilizer containing chelated trace elements; wherein the amount of the chelating substance added accounts for 10%-70% of the mass of the basic fertilizer.

[0016] The basic fertilizer is one or a mixture of potassium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium pyrophosphate, sodium pyrophosphate, potassium chloride, potassium sulfate, ammonium polyphosphate, urea, monoammonium phosphate, diammonium phosphate, ammonium sulfate, ammonium chloride, and ammonium nitrate;

[0017] When adding the basic fertilizer, the order of addition is appropriately adjusted according to the properties of the materials, and water is added, and the addition is carried out under stirring until the materials are completely dissolved.

[0018] The basic fertilizer is nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer or common nitrogen-phosphorus-potassium compound fertilizer.

[0019] When preparing liquid fertilizer, the supplementary basic fertilizer can be one or a mixture of potassium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium pyrophosphate, sodium pyrophosphate, potassium chloride, potassium sulfate, ammonium polyphosphate, urea, monoammonium phosphate, diammonium phosphate, ammonium sulfate, ammonium chloride, and ammonium nitrate. During the addition process, the addition order should be appropriately adjusted according to the different properties of the materials. Continue heating and stirring until all materials are completely dissolved, then stop heating, and adjust the volume to the designed volume to obtain liquid fertilizer containing chelated trace elements.

[0020] The environmentally friendly chelated element compound fertilizer can be used as foliar fertilizer, compound fertilizer or blended fertilizer.

[0021] The beneficial effects of the present invention are:

[0022] 1. Environmentally friendly, no pollution, no residue

[0023] The invention aims at the problem that EDTA chelated trace elements added to the current phosphorus-containing compound fertilizer cannot be absorbed and utilized by crops, and long-term application easily causes accumulation of EDTA in the soil. The invention selects a compound that is easy to degrade in the soil environment, and the product after degradation is a plant essential nutrient element and can be absorbed and utilized by the plant as a chelating agent. The chelating agent reacts with the plant essential metal element to form a chelated trace element, which can improve the absorption efficiency of the element, and the components of the chelating agent after decomposition can be absorbed and utilized by the plant, and will not remain in the soil, and will not cause potential harm to the soil.

[0024] 2. The production process is simple and easy to promote

[0025] The production process of the invention is simple, the production process is relatively safe, no solid or liquid waste is generated during the production process, and other nutrient elements can be appropriately added according to actual needs to form a composite fertilizer containing large, medium and trace elements.

[0026] 3. Filled the technological gap at home and abroad

[0027] At present, the chelated trace elements on the domestic and foreign markets are all in the chelated state of citric acid, humic acid, and EDTA, among which only EDTA chelated trace elements can be added to phosphorus-containing fertilizers without affecting the effectiveness of the trace elements. The present invention enriches the product choices of users. This product also contains phosphorus, which effectively supplements the trace elements for crops while also effectively supplementing the phosphorus element. It can effectively save product space during product development and design, and help to increase the nutrient content of the product. It provides a better raw material selection for the addition of trace elements in high-concentration fertilizers. The present invention fills the domestic technical and product gaps in this field. DETAILED DESCRIPTION

[0028] The specific implementation modes of the present invention are further described below in conjunction with examples. It should be noted that the specific implementation modes described here are only for illustrating and explaining the present invention, and are not limited to the present invention.

[0029] The present invention adopts a specific chelating agent to react with the necessary trace elements for crops under specific conditions to generate chelated substances (i.e., chelated trace elements). These chelated trace elements can be used alone as trace element fertilizers, or as raw materials to be further reacted with conventional nitrogen, phosphorus, and potassium single-element fertilizers or nitrogen, phosphorus, and potassium (binary or ternary) compound (mixed) fertilizers to produce macro-element fertilizers containing chelated elements.

[0030] The phosphorus-containing chelating agent has a high safety factor and higher biocompatibility, and has no harm to the environment during and after application. The phosphoric acid or phosphate produced by these phosphorus-containing chelating agents after degradation in the environment can also be absorbed and utilized by crops to provide phosphorus nutrition for crops.

[0031] The present invention firstly conducts a chelation reaction between phosphorus-containing macromolecules and metal ions under certain conditions to generate phosphorus-containing metal element chelates, which not only realizes the addition of trace elements in phosphorus-containing fertilizers without affecting the effectiveness of metal elements, but also increases the addition of phosphorus elements while adding trace elements, thereby effectively improving the effective content of nutrient elements in compound fertilizers. Phosphorus-containing macromolecules can improve the effectiveness of essential trace metal elements for plants while also effectively supplementing phosphorus elements. After decomposition, phosphorus-containing macromolecules can be converted into phosphate ions, which are absorbed and utilized by crops, thereby also realizing the slow release of phosphorus elements, extending the effective period of phosphorus fertilizers to a certain extent, improving the utilization rate of phosphorus fertilizers, and helping to reduce carbon emissions in fertilizer applications, and helping to reduce carbon emissions in fertilizer application fields.

[0032] Example 1

[0033] 30 parts by mass of aminotri(methylenephosphonic acid) (ATMP) and 54 parts by mass of water are put into a reactor with heating, stirring, temperature control and insulation facilities, the heating device is turned on and stirred at the same time to raise the system temperature to 40 degrees Celsius to completely dissolve the ATMP, the pH value of the system is adjusted to be close to 3 with ammonia water, and then the system temperature is adjusted to 30 degrees Celsius, and 16 parts of manganese sulfate monohydrate are put into the reactor, timing is started after the manganese sulfate is completely dissolved, and heating and stirring are performed for 50 minutes to obtain a chelated liquid fertilizer with a mass percentage of P2O5: 20% and Mn: 5.2%.

[0034] This product can be sprayed on the leaves or used with irrigation water to supplement phosphorus and manganese for crops at the same time. The fertilizer effect of phosphorus sprayed on the leaves can last for 30-50 days.

[0035] The water in the system can also be evaporated to dryness to make solid compound fertilizer for use.

[0036] Example 2

[0037] 32 parts by mass of 2-hydroxyphosphonoacetic acid (HPAA) and 41 parts of water are put into a reactor with heating, stirring, temperature control and insulation facilities, the heating device is turned on and stirred at the same time to raise the system temperature to 50 degrees Celsius to completely dissolve the HPAA, and the pH value of the system is adjusted to be close to 3.5 with ammonia water, and then 27 parts of zinc chloride are put into the reactor, and timing is started after the zinc chloride is completely dissolved, and heating and stirring are performed for 45 minutes to obtain a chelated zinc liquid fertilizer containing P2O5: 14% and Zn: 12.9% measured by mass percentage.

[0038] Then add 10 parts of water to the system, stir evenly, add 70 parts of dipotassium hydrogen phosphate and 20 parts of urea to the system, and after the materials are completely dissolved and cooled, a chelated liquid fertilizer containing N: 4.6%, P2O5: 25.4%, K2O: 18.2%, and Zn: 6.3% by mass is obtained.

[0039] The water in the system can also be evaporated to dryness to make solid compound fertilizer for use.

[0040] Example 3

[0041] Get 29 parts of diethylenetriamine penta methylene phosphonic acids (DETPMP) by mass fraction, 58 parts of water are put in the reactor with heating, stirring, temperature control and insulation facilities, open heater and stir simultaneously and make system temperature rise to 40 degrees Celsius, DETPMP is dissolved fully, with ammoniacal liquor regulating system pH value close to 3.5, then 13 parts of ferrous sulfate heptahydrate are put in the reactor, timing after ferrous sulfate heptahydrate dissolves fully, heated and stirred 30 minutes, namely obtain measuring with mass percentage and contain P2O517.4%, ferrous 2.6% chelated iron liquid fertilizer.

[0042] Then, 80 parts of potassium pyrophosphate and 20 parts of urea were added into the system, and the materials were cooled after being completely dissolved to finally obtain a chelated liquid fertilizer containing 4.6% N, 23.4% P2O5, 19.6% K2O and 1.3% Fe by mass.

[0043] The water in the system can also be evaporated to dryness to make solid compound fertilizer for use.

[0044] Example 4

[0045] Take 21 parts of hydroxyethylidene diphosphonic acid (HEDP) by mass and 55 parts of water and put them into a reactor with heating, stirring, temperature control and insulation facilities. Turn on the heating device and stir at the same time to raise the system temperature to 50 degrees Celsius to completely dissolve the HEDP. Use ammonia water to adjust the system pH value to close to 2, then put 24 parts of cupric sulfate pentahydrate into the reactor, start timing after the cupric sulfate pentahydrate is completely dissolved, heat and stir for 20 minutes, and obtain a chelated copper liquid fertilizer containing 14% P2O5 and 6% copper by mass percentage.

[0046] Then add 10 parts of water to the system, mix evenly, add 50 parts of ammonium polyphosphate and 40 parts of urea to the system, wait for the materials to be completely dissolved and cooled, and finally obtain a chelated liquid fertilizer containing 13.4% N, 21.7% P2O5 and 3% Cu by mass.

[0047] The water in the system can also be evaporated to dryness to make solid compound fertilizer for use.

[0048] Example 5

[0049] Take 25 parts by mass of hexamethylenediaminetetramethylenephosphonic acid (HDTMPA) and 70 parts by mass of water, put them into a reactor with heating, stirring, temperature control and insulation facilities, turn on the heating device and stir at the same time to raise the system temperature to 30 degrees Celsius to completely dissolve the HDTMPA, adjust the system pH value to near 4 with potassium hydroxide, then put 5 parts of anhydrous calcium chloride into the reactor, start timing after the anhydrous calcium chloride is completely dissolved, heat and stir for 30 minutes, and obtain a chelated calcium liquid fertilizer containing 14% P2O5 and 1.8% calcium by mass percentage.

[0050] Then add 70 parts of potassium pyrophosphate into the system, mix evenly, add 20 parts of ammonium polyphosphate into the system, wait for the materials to be completely dissolved and cooled, and finally obtain a chelated calcium liquid fertilizer with a mass percentage of N1.7%, P2O5 29%, K2O: 20%, and Ca 9‰.

[0051] The water in the system can also be evaporated to dryness to make solid compound fertilizer for use.

[0052] Example 6

[0053] Take 30 parts by mass of hexamethylenediaminetetramethylenephosphonic acid (HPAA) and 28 parts of water and put them into a reactor with heating, stirring, temperature control and insulation facilities, turn on the heating device and stir at the same time to raise the system temperature to 60 degrees Celsius to completely dissolve the HPAA, use potassium hydroxide to adjust the system pH value to close to 5, then put 16.8 parts of zinc sulfate heptahydrate into the reactor and heat and stir, after the system is clarified, add 11 parts of ferrous sulfate heptahydrate thereto and continue heating and stirring, after the system is clarified, put 9.2 parts of manganese sulfate monohydrate and 5 parts of copper sulfate pentahydrate into the reactor and heat and stir until the system is clarified, and obtain a phosphorus-containing multi-chelate liquid fertilizer containing P2O5 13.5%, Mn: 2.9%, Fe: 2.2%, Zn: 3.7%, and Cu: 1.25% by mass percentage.

[0054] The water in the system can also be evaporated to dryness to make solid compound fertilizer for use.

[0055] Example 7

[0056] Take 22 parts by mass of hexamethylenediaminetetramethylenephosphonic acid (HPAA) and 47 parts of water and put them into a reactor with heating, stirring, temperature control and insulation facilities, turn on the heating device and stir at the same time to raise the system temperature to 50 degrees Celsius to completely dissolve the HPAA, use potassium hydroxide to adjust the pH value of the system to close to 3, then put 16.8 parts of zinc sulfate heptahydrate into the reactor and heat and stir, after the system is clarified, put 9.2 parts of manganese sulfate monohydrate and 5 parts of copper sulfate pentahydrate into the reactor and heat and stir until the system is clarified, and obtain a multi-chelate liquid fertilizer containing P2O5: 9.9%, Mn: 2.9%, Zn: 3.7%, and Cu: 1.25% by mass percentage.

[0057] 40 parts of water can be added to the above system, mixed evenly, and then 50 parts of urea and 10 parts of potassium nitrate are added to the system. After the materials are completely dissolved and cooled, a multi-chelate liquid fertilizer containing N: 12.2%, P2O5: 4.9%, K2O: 2.3%, Mn: 1.4%, Zn: 1.8%, and Cu: 6‰ is finally obtained.

[0058] The water in the system can also be evaporated to dryness to make solid compound fertilizer for use.

[0059] Example 8

[0060] Take 11 parts of hydroxyethylidene diphosphonic acid (HEDP), 15 parts of aminotri(methylene phosphonic acid) (ATMP) and 63 parts of water by mass and put them into a reactor with heating, stirring, temperature control and insulation facilities. Turn on the heating device and stir at the same time to raise the system temperature to 40 degrees Celsius to completely dissolve HEDP and ATMP. Use ammonia water to adjust the pH value of the system to close to 4. Then put 6 parts of zinc chloride into the reactor and heat and stir. After the system is clarified, add 5 parts of calcium chloride and continue heating and stirring until the system is clarified, so as to obtain a multi-chelated liquid fertilizer containing P2O5: 17.7%, Zn: 2.8% and Ca: 1.8% by mass percentage.

[0061] Then add 40 parts of water to the system, mix evenly, then add 20 parts of diammonium phosphate and 40 parts of urea to the system, stir and heat, wait for the materials to be completely dissolved and cool, and finally obtain a chelated calcium liquid fertilizer with a mass percentage of N: 11%, P2O5: 13.4%, Zn: 1.4%, and Ca: 9‰.

[0062] The water in the system can also be evaporated to dryness to make solid compound fertilizer for use.

[0063] Effect verification experiment:

[0064] The liquid fertilizer manufactured in the embodiment and a control fertilizer with the same nutrient content were diluted and then sprayed on corn plants. The content of related elements in corn leaves was measured 15 days after spraying to test the effects of the homemade chelated trace element fertilizer and compound fertilizer.

[0065] The sample weights of the embodiments and controls are as follows:

[0066]

[0067]

[0068] Add the above samples to the container and add water to make up to 15L. Dissolve and shake well, then take 500ml for each treatment and spray evenly on the corn in a plot area of ​​20 square meters (4m×5m). After 15 days, measure the corresponding nutrient content (drying basis) in the corn plants according to the treatment conditions. The results are as follows:

[0069]

[0070] It can be seen from the above table that under the condition of the same amount of nutrient elements, the application effect of the chelated elements manufactured by the present invention is better than that of the EDTA chelated elements, and the chelating agent used in the present invention has a certain biocompatibility and will not cause harm to soil organisms and humans. At the same time, its degradation products can also provide phosphorus nutrition for crops. If the EDTA chelated element is to increase the phosphorus content, it needs to be added additionally, which increases the inconvenience of farmers in use; and then further evaluate the other properties of the chelated substance obtained by the embodiment of the present invention.

[0071] Degradation test of chelated substances in soil:

[0072] The chelate obtained in Example 2 and the EDTA chelate were selected to carry out an indoor soil culture test to study the soil degradation performance of the two chelating agents. The soil used for soil culture was collected from a corn field in the north of Nanhuang Village, Gaohua Town, Tiexi District, Shenyang City. The soil type of the plot was brown soil with medium soil fertility, 21.39 g / kg of organic matter, 92.36 mg / kg of available nitrogen, 33.25 mg / kg of available phosphorus, 157.35 mg / kg of available potassium, and a soil pH of 6.5.

[0073] The soil samples were mixed and crushed evenly and passed through a 20-mesh sieve for later use. Then, 200 g of air-dried soil was weighed for each treatment and mixed with the fertilizer sample. The specific treatments are as follows:

[0074] Treatment 1: 200 g of air-dried soil and 20 g of the product of Example 2 were mixed evenly and placed in a culture container for later use.

[0075] Treatment 2: Mix 200 g of air-dried soil and 18.27 of the control 2 mixture evenly and place them in a culture container for later use.

[0076] Add distilled water to the culture container to keep the soil moisture content at 60% of the field water holding capacity, then place the container in a constant temperature incubator at 25°C for culture, take samples every 10 days, rinse with distilled water, and after the eluent is fixed to volume, use liquid chromatography to determine the HPAA-Zn and EDTA-Zn content in the eluent and calculate the mass of the chelating agent leached out for each treatment. The results are shown in the following table:

[0077] Amount of chelated substances leached from soil

[0078]

[0079] When the composite fertilizer of the present invention is applied as foliar fertilizer, the rapid degradation of the chelated elements is required. Under the premise of ensuring that the chelated metal elements are effectively absorbed by the crops, the phosphorus elements released after degradation can also be absorbed and utilized by the plants, so as to timely supplement the phosphorus nutrition for the crops. As can be seen from the above table, the degradation rate of HPAA-Zn in brown soil does not exceed 30 days, while the degradation of EDTA-Zn in brown soil takes about 110 days. Therefore, the potential harm of the new chelating agent used in the present invention to the soil environment is much lower than that of EDTA chelated fertilizer. Therefore, the new inhibitor has no residue in the environment and has no adverse effect on the agricultural ecological environment.

Claims

1. An environmentally friendly chelated element compound fertilizer, characterized in that: The compound fertilizer is a chelating substance, or a chelating substance is added to the basic fertilizer; wherein the chelating substance is a substance obtained by a mixed reaction of a chelating agent and a metal salt, and the molar ratio between the chelating agent and the metal salt is between 1:0.97-1:0.30; The chelating agent is 2-hydroxyphosphonoacetic acid (HPAA); The chelating substance is a chelating agent which is dissolved in water and heated and stirred at 30-60°C. After it is completely dissolved, the pH value of the solution is adjusted to 2-5, and then the metal salt is added. The original system temperature is maintained and stirred for 20-60 minutes to allow it to fully react. The metal salt is one or more of metal sulfate, nitrate and chloride; the metal is zinc.

2. The environmentally friendly chelated element compound fertilizer according to claim 1, characterized in that: A chelating substance is added to the basic fertilizer, and the amount of the chelating substance added accounts for 10%-70% of the mass of the basic fertilizer; wherein the basic fertilizer is nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer or ordinary nitrogen-phosphorus-potassium compound fertilizer.

3. A biological preparation method of an environmentally friendly chelated element compound fertilizer according to claim 1, characterized in that: The compound fertilizer is a chelating substance, or a chelating substance is added to the basic fertilizer; wherein the chelating substance is a substance obtained by a mixed reaction of a chelating agent and a metal salt, and the molar ratio between the chelating agent and the metal salt is between 1:0.97-1:0.30; The compound fertilizer is a chelating agent dissolved in water and heated and stirred at 30-60°C. After it is completely dissolved, the pH value of the solution system is adjusted to 2-5, and then a metal salt is added. The original system temperature is maintained and stirred for 20-60 minutes to allow it to fully react, so as to obtain a chelating substance as a compound fertilizer.

4. The method for biologically preparing the environmentally friendly chelated element compound fertilizer according to claim 3, characterized in that: The compound fertilizer is prepared by controlling the system temperature at 40-60 degrees Celsius after the chelating substance system is reacted and the solution is clarified, adding various materials of the basic fertilizer under stirring conditions to completely dissolve, then stopping heating and adjusting the volume to obtain a liquid fertilizer containing chelated trace elements; wherein the amount of the chelating substance added accounts for 10%-70% of the mass of the basic fertilizer.

5. The method for biologically preparing the environmentally friendly chelated element compound fertilizer according to claim 3, characterized in that: The basic fertilizer is one or a mixture of potassium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium pyrophosphate, sodium pyrophosphate, potassium chloride, potassium sulfate, ammonium polyphosphate, urea, monoammonium phosphate, diammonium phosphate, ammonium sulfate, ammonium chloride, and ammonium nitrate; When adding the basic fertilizer, the order of addition is appropriately adjusted according to the properties of the materials, and water is added, and the addition is carried out under stirring until the materials are completely dissolved.

Images