A citric acid chelated trace element liquid fertilizer and preparation method thereof

Abstract

The present application discloses a citric acid chelated trace element liquid fertilizer, which is prepared by diluting a chelated mother liquor; the chelated mother liquor is prepared from the following raw materials in parts by weight: citric acid, water, 1.5 to 3.0 parts of iron, 1.0 to 2.6 parts of zinc, 1.3 to 2.5 parts of manganese, 0.3 to 1.0 parts of boron, and 0.1 to 0.3 parts of a surfactant; the pH value of the chelated mother liquor is 2.2 to 3.2; a reducing agent is also added to the chelated mother liquor, and the reducing agent is elemental iron and / or elemental zinc. The citric acid chelated trace element liquid fertilizer and preparation method provided by the present application solve the problems of extremely low absorption and utilization rate of water-soluble trace element fertilizers on the current market, long chelation reaction time in fertilizer production, high energy consumption and cost, complex preparation, difficulty in decomposition, lack of economy and practicality.

Description

Technical Field

[0001] The invention belongs to the technical field of fertilizer production, and in particular relates to a citric acid chelated trace element liquid fertilizer and a preparation method thereof. Background Art

[0002] Chelated trace element liquid fertilizer is a fertilizer made of chelating agents and trace elements essential to plants, such as chelated zinc, chelated iron, chelated manganese, chelated copper, etc. Chelated trace element liquid fertilizer is better than solid or inorganic trace element fertilizer. It is not easily fixed in the soil, is easily soluble in water, and does not dissociate. It can be well absorbed and utilized by plants. It can also be mixed with other solid or liquid fertilizers without chemical reaction and without reducing the fertilizer efficiency of any fertilizer.

[0003] At present, most of the trace element water-soluble fertilizers on the market are in an inorganic state, and the absorption and utilization rate is extremely low. In addition, in the preparation process of the chelated trace element fertilizers on the market, EDTA (ethylenediaminetetraacetic acid) is used, which is a traditional chelating agent widely used in various fields, while EDDHA (sodium ethylenediaminedi-o-phenylacetate) is a new chelating agent, which has higher bioavailability and stability after chelation. However, due to the long chelation reaction time of EDTA and EDDHA, high energy consumption and cost, complex preparation, difficult decomposition, easy accumulation in the soil, causing pollution to the environment, lack of economy and environmental protection. Summary of the invention

[0004] In order to solve the deficiencies of the prior art, the present invention provides a citric acid chelated trace element liquid fertilizer and a preparation method thereof, the purpose of which is to solve the problems of extremely low absorption and utilization rate of trace element water-soluble fertilizers on the current market, long chelation reaction time in the fertilizer production process, high energy consumption and cost, complex preparation, difficulty in decomposition, lack of economy and practicality.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] A citric acid chelated trace element liquid fertilizer, which is prepared by diluting the chelated mother solution;

[0007] The chelating mother solution is prepared from the following raw materials in parts by weight:

[0008] Citric acid, water, 1.5-3.0 parts of iron, 1.0-2.6 parts of zinc, 1.3-2.5 parts of manganese, 0.3-1.0 parts of boron, and 0.1-0.3 parts of a surfactant; the amount of citric acid used is 1-2 times the total molar amount of iron, zinc and manganese in terms of molar ratio; the amount of water used is 40-80% of the mass percentage of the chelating mother liquor;

[0009] The pH value of the chelating mother solution is 2.2 to 3.2;

[0010] A reducing agent is also added to the chelating mother liquor, and the reducing agent is elemental iron and / or elemental zinc.

[0011] Preferably, the iron element is derived from ferrous sulfate and / or ferrous sulfate hydrate; the zinc element is derived from zinc sulfate and / or zinc sulfate hydrate; the manganese element is derived from manganese sulfate; and the boron element is derived from boric acid and / or borax.

[0012] Preferably, the surfactant is a natural surfactant.

[0013] Preferably, the natural surfactant is selected from betaine and / or sugar alcohol compounds.

[0014] Preferably, the amount of citric acid used is 1.05 to 1.5 times the total molar amount of iron, zinc and manganese elements in terms of molar ratio.

[0015] Preferably, the pH value of the chelating mother solution is 2.7-3.1.

[0016] The preparation method of the citric acid chelated trace element liquid fertilizer as described above comprises the following steps:

[0017] S1. Add citric acid in a formula ratio to water, and then add trace elements and surfactants in sequence;

[0018] S2. The chelating reaction is carried out under stirring conditions at a temperature of 65 to 95° C. for a reaction time of 35 to 45 min;

[0019] S3. Using potassium hydroxide to adjust the solution pH to 2.2-3.2;

[0020] S4. Then a reducing agent is added and mixed to obtain a chelating mother liquor; a reducing agent is added in portions during storage of the chelating mother liquor;

[0021] S5. When using, dilute the chelated mother solution by a certain multiple to obtain liquid fertilizer.

[0022] Preferably, the reaction temperature in step S2 is 75-85°C.

[0023] Preferably, the pH of the solution in step S3 is 2.7 to 3.1.

[0024] Preferably, the trace elements are added in the order of iron, zinc, manganese and boron.

[0025] The citric acid chelated trace element liquid fertilizer and preparation method provided in the present application solve the problems of extremely low absorption and utilization rate of trace element water-soluble fertilizers on the current market, long chelation reaction time in the fertilizer production process, high energy consumption and cost, complex preparation, difficult decomposition, lack of economy and practicality. DETAILED DESCRIPTION

[0026] The present application provides a citric acid chelated trace element liquid fertilizer, which is prepared by diluting a chelated mother liquor; the chelated mother liquor is prepared from the following raw materials in parts by weight:

[0027] Citric acid, water, 1.5-3.0 parts of iron, 1.0-2.6 parts of zinc, 1.3-2.5 parts of manganese, 0.3-1.0 parts of boron and 0.1-0.3 parts of surfactant; the amount of citric acid used is 1-2 times the total molar amount of iron, zinc and manganese in terms of molar ratio; the amount of water used is 40-80% of the mass percentage of the chelating mother liquor; a reducing agent is further added to the chelating mother liquor, and the reducing agent is elemental iron and / or elemental zinc; the pH value of the chelating mother liquor is 2.2-3.2.

[0028] Citric acid is a cheap and environmentally friendly organic acid. In the growth and environmental adaptation of plants, the citric acid metabolic pathway plays an important role. From the growth aspect, citric acid is a nutrient necessary for plant growth and development, and thus multiple plant growth processes, such as photosynthesis, respiration, metabolic pathways, etc., can be covered. The present application adopts citric acid as a chelating agent, and uses water as a catalyst, which can quickly and efficiently chelate trace elements to obtain a fully water-soluble liquid fertilizer without precipitation. The added iron and zinc reductants can effectively prevent ferrous ion oxidation, improve the stability of the chelating liquid, and can also be used as a supplement of iron and zinc trace elements to further increase the liquid fertilizer nutrient content. The surfactant therein has a certain spatial force, which not only promotes chelation, but also reduces the surface tension of plant leaves, further promoting absorption.

[0029] Therefore, the product formed after chelation with citric acid has high biological activity, can be absorbed by crops or animals in an organic molecular state, directly participate in the conversion process, is easier to be utilized by organisms than inorganic salts, and has a higher utilization rate. Compared with traditional EDTA chelating agents, it is easy to degrade and has good safety. Moreover, it has good sustained release and long lasting effect, which reduces the loss of trace elements in the soil or plants, reduces the use of trace elements, and reduces resource waste. The addition of a reducing agent can effectively avoid ferrous oxidation and further improve the utilization rate of liquid fertilizer elements.

[0030] Preferably, the iron element is derived from ferrous sulfate and / or ferrous sulfate hydrate; the zinc element is derived from zinc sulfate and / or zinc sulfate hydrate; the manganese element is derived from manganese sulfate; and the boron element is derived from boric acid and / or borax.

[0031] Preferably, the surfactant is a natural surfactant. Further, the natural surfactant is selected from betaine and / or sugar alcohol compounds. Betaine and sugar alcohol compounds are small molecule natural surfactants, which can reduce the damage to plant leaves and have high safety compared with high molecular chemical synthetic surfactants.

[0032] Preferably, the amount of citric acid used is 1.05 to 1.5 times the total molar amount of iron, zinc and manganese in terms of molar ratio. Excessive citric acid can fully chelate trace elements (citric acid cannot chelate boron), but the amount of citric acid used should not be too high, otherwise it will reduce the pH of the solution and cause damage to plants.

[0033] Preferably, the pH value of the chelating mother solution is 2.7 to 3.1. Experiments have shown that within this range, a higher chelating rate is achieved. The pH of the system is preferably adjusted using potassium hydroxide. Potassium hydroxide is used to adjust the pH of the system, and potassium is also a nutrient required for plant growth, further increasing the nutrient content of the liquid fertilizer.

[0034] On the other hand, the present application also provides a method for preparing the citric acid chelated trace element liquid fertilizer as described above, comprising the following steps:

[0035] S1. Add citric acid in a formula ratio to water, and then add trace elements and surfactants in sequence;

[0036] S2. The chelating reaction is carried out under stirring conditions at a temperature of 65 to 95° C. for a reaction time of 35 to 45 min;

[0037] S3. The pH of the solution is adjusted to 2.2 to 3.2 using potassium hydroxide; potassium hydroxide is added to the chelating solution after the reaction is completed to adjust the pH to maintain a stable solubility and prevent the precipitation of trace elements;

[0038] S4. Then add the reducing agent, mix well, and obtain the chelating mother liquor. The reducing agent is added several times during the storage of the chelating mother liquor. Since ferrous iron is easily oxidized to form trivalent iron that is not suitable for crop absorption, adding a certain amount of reducing agent iron and / or zinc can effectively prevent ferrous iron oxidation. Since ferrous iron oxidation is a continuous process, and the reducing agent should not be added in excess at one time to avoid affecting the stability of the chelating mother liquor, the reducing agent is preferably added in several times; the amount added each time is preferably 0.01 to 0.02 parts; the interval time can be based on whether there is still a reducing agent in the mother liquor (iron oxide is brown in color, which is different from the color of elemental iron and zinc and can be easily observed and distinguished);

[0039] S5. When using, dilute the chelated mother solution by a certain multiple to obtain liquid fertilizer.

[0040] Experiments have shown that the main factors affecting the chelation effect are reaction temperature, reaction pH and the ratio of citric acid to trace elements. The amount of citric acid also has an important influence on the pH of the system. A certain high temperature and pH are conducive to chelation, so that the solubility of iron, manganese and zinc reaches the optimal state without producing precipitation. Using excess citric acid can fully chelate the trace elements.

[0041] Adding water, citric acid and trace elements in sequence can ensure that the pH of the system is stable within a certain range before the trace elements are added, which helps to dissolve the trace elements and ensure that the elements will not precipitate, while satisfying the chelating effect of citric acid; further, the order of adding trace elements is iron, zinc, manganese, and boron, and iron is added first to reduce the oxidation of ferrous ions under acidic conditions.

[0042] Preferably, the reaction temperature in step S2 is 75-85°C.

[0043] Preferably, the pH of the solution in step S3 is 2.7 to 3.1.

[0044] Preferably, the chelated mother solution is diluted a certain multiple when used and sprayed on the leaves of crops, that is, used as foliar fertilizer, which can improve the crop absorption efficiency compared with direct application to the soil.

[0045] Therefore, the citric acid chelated trace element liquid fertilizer and preparation method provided in the present application solve the problems of extremely low absorption and utilization rate of trace element water-soluble fertilizers on the current market, long chelation reaction time in the fertilizer production process, high energy consumption and cost, complex preparation, difficult decomposition, lack of economy and practicality.

[0046] Through the analysis of the soil content of hundreds of places in Xinjiang, it is found that the soil in Xinjiang is alkaline, and the content of trace elements in the soil is not high. Therefore, the acidic liquid fertilizer provided by this application is very suitable for crop planting in Xinjiang.

[0047] Example 1

[0048] S1. In parts by weight, 50 parts of water were added to the reactor, followed by 22 parts of citric acid, 14 parts of ferrous sulfate heptahydrate, 3.5 parts of zinc sulfate monohydrate, 6 parts of manganese sulfate, 4.3 parts of boric acid and 0.2 parts of betaine; the amount of citric acid added was 1.05 times the total molar amount of iron, zinc and manganese;

[0049] S2. reacting at 75°C with stirring for 45 min;

[0050] S3. Add potassium hydroxide to adjust the pH to 2.4;

[0051] S4. Add 0.01 parts of iron powder and mix well to obtain a chelating mother solution; observe the amount of iron oxide generated and the remaining amount of iron powder during storage, and add new iron powder in time when the iron powder is insufficient.

[0052] According to the test, the chelation rate of trace elements under the reaction conditions reached 96.91%.

[0053] When the reaction temperature was 65℃ as the control, the chelation rate was 95.68%; when the reaction temperature was 70℃ as the control, the chelation rate was 96.34%; when the reaction temperature was 95℃ as the control, the chelation rate was 96.35%. When the reaction temperature was 50℃, the chelation rate was only 91%; when the reaction temperature was 100℃, the chelation rate was only 92%.

[0054] Therefore, it can be found from the above data that the reaction temperature has a significant effect on the chelation rate, and the reaction temperature is preferably 65-95°C.

[0055] Example 2

[0056] S1. In parts by weight, 60 parts of water were added to the reactor, followed by 18 parts of citric acid, 10.5 parts of ferrous sulfate heptahydrate, 3.6 parts of zinc sulfate monohydrate, 4.3 parts of manganese sulfate, 3.5 parts of boric acid and 0.1 parts of betaine, the amount of citric acid added was 1.09 times the total molar amount of trace elements of iron, zinc and manganese in moles;

[0057] S2. reacting at 80°C with stirring for 40 min;

[0058] S3. Add potassium hydroxide to adjust the pH to 2.7;

[0059] S4. Add 0.01 parts of iron powder and mix well to obtain the chelating mother solution; observe the amount of iron oxide generated and the remaining amount of iron powder during storage, and add new iron powder in time when the iron powder is insufficient.

[0060] According to the test, the chelation rate of trace elements under the reaction conditions reached 98.54%.

[0061] When the amount of citric acid was 1 times the amount of trace elements, as a control, the chelation rate was 97.12%; when the amount of citric acid was 1.5 times the amount of trace elements, as a control, the chelation rate was 98.03%. When the amount of citric acid was 0.9 times, the chelation rate was only 85%; when the amount of citric acid was 2.2 times, the chelation rate was only 88%.

[0062] Therefore, it can be found from the above data that the raw material ratio also has a significant effect on the chelation rate. When the amount of citric acid is too little, the trace elements cannot be fully chelated. Secondly, the reaction pH is also high, which affects the chelation effect. Similarly, when the amount of citric acid is too much, although there is enough citric acid to chelate the trace elements, the reaction pH is too low, which also reduces the chelation effect. Therefore, it is preferred that the amount of citric acid is 1 to 2 times the molar amount of the trace elements.

[0063] Example 3

[0064] S1. In parts by weight, 60 parts of water were added to the reactor, followed by 20 parts of citric acid, 9.8 parts of ferrous sulfate heptahydrate, 3.2 parts of zinc sulfate monohydrate, 3.8 parts of manganese sulfate, 3.1 parts of boric acid and 0.1 parts of betaine, the amount of citric acid added was 1.33 times the total molar amount of trace elements of iron, zinc and manganese in moles;

[0065] S2. react at 85°C with stirring for 35 min;

[0066] S3. Add potassium hydroxide to adjust the pH to 3.1;

[0067] S4. Add 0.01 parts of iron powder and mix well to obtain the chelating mother solution; observe the amount of iron oxide generated and the remaining amount of iron powder during storage, and add new iron powder in time when the iron powder is insufficient.

[0068] According to the test, the chelation rate of trace elements under the reaction conditions reached 98.14%.

[0069] Application test

[0070] (1) Test 1

[0071] Test crop: Wheat (New Winter 22)

[0072] Test soil: loam, medium fertility, uniform soil fertility

[0073] Treatment method: The test was carried out strictly in accordance with the requirements of the technical regulations for field test of fertilizer effect identification [NY / T 497-2002]. Under the premise of consistent high-yield cultivation management measures such as tillage, drainage and irrigation, improved varieties, density, and prevention and control of pests and diseases, in addition to the application of the citric acid chelated trace element liquid fertilizer of the present invention, the application amount and method of other fertilizers and field management were carried out according to local customs. A randomized block arrangement test design was adopted, with 3 test points, 2 treatments and 3 replicates at each test point, and each wheat sample segment was 0.667m 2 Area sampling and yield measurement.

[0074] The test treatment is:

[0075] Treatment 1 (T1), conventional fertilization + foliar spraying of citric acid chelated trace element liquid fertilizer diluted with the chelated mother solution of Example 1 of the present invention (the dilution multiple is 40 times, and the chelated mother solution is first filtered to remove the precipitate before dilution);

[0076] Treatment 2 (T2), customary fertilization + foliar spraying of equal content solid trace elements.

[0077] The results are shown in Table 1.

[0078] The results of field yield measurement showed that the T2 treatment performed significantly better in terms of plant height, with an average increase of 6.1 cm in plant height compared with the T1 treatment. The number of spikes in T1 increased by an average of 15.8 spikes / 0.667 m compared with T2. 2 The thousand-grain weight increased by an average of 3.6g, the theoretical yield increased by an average of 48.6kg / mu, the yield increase range was 5.8% to 12.3%, and the average yield increase was 9.6%.

[0079] Table 1

[0080]

[0081] (2) Test 2

[0082] Test crop: corn (MC610)

[0083] Test soil: loam, medium fertility, uniform soil fertility

[0084] Treatment method: The test was carried out strictly in accordance with the requirements of the technical regulations for field test of fertilizer effect identification [NY / T 497-2002]. Under the premise of consistent high-yield cultivation management measures such as tillage, drainage and irrigation, improved varieties, density, and prevention and control of pests and diseases, in addition to the application of the citric acid chelated trace element liquid fertilizer of the present invention, the application amount and method of other fertilizers and field management were carried out according to local customs. A randomized block arrangement test design was adopted, with 2 test points, 2 treatments and three replicates at each test point, and each corn sample segment was 6.67m 2 Area sampling and yield measurement.

[0085] The test treatment is:

[0086] Treatment 1 (T1), conventional fertilization + foliar spraying of citric acid chelated trace element liquid fertilizer diluted with the chelate mother solution of Example 3 of the present invention (the dilution multiple is 40 times, and the chelate mother solution is first filtered to remove the precipitate before dilution);

[0087] Treatment 2 (T2), customary fertilization + foliar spraying of equal content solid trace elements.

[0088] The results are shown in Table 2.

[0089] According to the field yield measurement results (Table 2), the number of grains per ear of T1 increased by 15.7 compared with T2, the weight of a single ear of T1 increased by 11.9g compared with T2, and the weight of 100 grains of T1 increased by 1.15g compared with T2; the corn yield of T1 increased by 63.8kg / mu compared with T2, the increase range was 5.2% to 7.3%, and the average increase rate reached 6.3%.

[0090] Table 2

[0091]

[0092] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A citric acid chelated trace element liquid fertilizer, characterized in that: It is prepared by diluting the chelating mother liquor; The chelating mother solution is prepared from the following raw materials in parts by weight: Citric acid, water, 1.5-3.0 parts of iron, 1.0-2.6 parts of zinc, 1.3-2.5 parts of manganese, 0.3-1.0 parts of boron, and 0.1-0.3 parts of a surfactant; the amount of citric acid used is 1-2 times the total molar amount of iron, zinc and manganese in terms of molar ratio; the amount of water used is 40%-80% of the mass percentage of the chelating mother liquor; The pH value of the chelating mother solution is 2.2 to 3.2; A reducing agent is also added to the chelating mother liquor, and the reducing agent is elemental iron and / or elemental zinc.

2. The citric acid chelated trace element liquid fertilizer according to claim 1, characterized in that The iron element is derived from ferrous sulfate and / or ferrous sulfate hydrate; the zinc element is derived from zinc sulfate and / or zinc sulfate hydrate; the manganese element is derived from manganese sulfate; and the boron element is derived from boric acid and / or borax.

3. The citric acid chelated trace element liquid fertilizer as claimed in claim 1, characterized in that, The surfactant is a natural surfactant.

4. The citric acid chelated trace element liquid fertilizer as claimed in claim 3, characterized in that, The natural surfactant is selected from betaine and / or sugar alcohol compounds.

5. The citric acid chelated trace element liquid fertilizer as claimed in claim 1, characterized in that, The amount of citric acid used is 1.05 to 1.5 times the total molar amount of the iron element, the zinc element and the manganese element, based on a molar ratio.

6. The citric acid chelated trace element liquid fertilizer according to claim 1, characterized in that, The pH value of the chelating mother solution is 2.7-3.

1.

7. The method for preparing the citric acid chelated trace element liquid fertilizer according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Add citric acid in a formula ratio to water, and then add trace elements and surfactants in sequence; S2. The chelating reaction is carried out under stirring conditions at a temperature of 65 to 95°C and a reaction time of 35 to 45 min; S3. Using potassium hydroxide to adjust the solution pH to 2.2-3.2; S4. Then a reducing agent is added and mixed to obtain a chelating mother liquor; a reducing agent is added in portions during storage of the chelating mother liquor; S5. When using, dilute the chelated mother solution by a certain multiple to obtain liquid fertilizer.

8. The preparation method of citric acid chelated trace element liquid fertilizer as claimed in claim 7, characterized in that, The reaction temperature in step S2 is 75-85°C.

9. The method for preparing the citric acid chelated trace element liquid fertilizer as claimed in claim 7, characterized in that: The pH of the solution in step S3 is 2.7 to 3.

1.

10. The method for preparing the citric acid chelated trace element liquid fertilizer according to claim 7, characterized in that: The trace elements are added in the order of iron, zinc, manganese and boron.

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