Potassium slow-release fertilizer as well as preparation method and application thereof

Abstract

The invention discloses a potassium slow-release fertilizer as well as a preparation method and application thereof. The potassium slow-release fertilizer comprises potassium-based manganese ore and a controlled-release agent loaded on the potassium-based manganese ore; the controlled release agent comprises at least one of 2, 6-anthraquinone disulfonic acid and lactate. According to the potassium slow-release fertilizer, the controlled-release agent is loaded through the potassium-based manganese ore, release of the potassium element and the manganese element in the potassium-based manganese ore is promoted through the controlled-release agent, and therefore the content of potassium and manganese in soil is increased, specifically, after the potassium slow-release fertilizer is applied to the soil for 9 days, the potassium element can be slowly released by more than or equal to 85 mg / L, and when the application amount of the potassium slow-release fertilizer in the soil is increased, the potassium element can be slowly released by more than or equal to 85 mg / L; the release amount of the potassium element can reach about 800mg / L.

Description

Technical Field

[0001] The invention belongs to the field of fertilizers, and in particular relates to a potassium slow-release fertilizer and a preparation method and application thereof. Background Art

[0002] Potassium is an essential trace element for the human body and is vital to health. Potassium maintains electrolyte balance, is essential for heart and muscle function, and can prevent chronic diseases. Manganese minerals in nature are diverse due to their different oxidation states and structures. In theory, even the Mn in tetravalent manganese minerals is not a single Mn. 4+ There is, and there is Mn 3+ , Mn 2+ Plasma valence state. Potassium salts such as potassium permanganate and potassium carbonate are often used in the preparation of different manganese minerals, so that potassium can be used as interlayer and tunnel filling ions to neutralize negative charges. Previous studies have focused on the differences in the oxidation and adsorption properties of manganese ore structures, and have been used to remove inorganic and organic pollution in soil, water, and the atmosphere. It has not been found that manganese ores with different structures are used in agricultural production to examine their effects on soil as fertilizers. Summary of the invention

[0003] In order to overcome at least one technical problem existing in the above-mentioned prior art, one of the purposes of the present invention is to provide a potassium slow-release fertilizer.

[0004] A second object of the present invention is to provide a method for preparing a potassium slow-release fertilizer.

[0005] The third object of the present invention is to provide the application of the above-mentioned potassium slow-release fertilizer or potassium-based manganese ore in the field of fertilizers.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The first aspect of the present invention provides a potassium slow-release fertilizer, comprising potassium-based manganese ore and a controlled-release agent loaded on the potassium-based manganese ore; the controlled-release agent comprises at least one of 2,6-anthraquinone disulfonic acid and lactate.

[0008] In some embodiments of the present invention, the lactate comprises at least one of sodium lactate, magnesium lactate, and lactic acid.

[0009] In some embodiments of the present invention, the sodium lactate is selected from at least one of L-sodium lactate, DL-sodium lactate, and D-sodium lactate.

[0010] In some embodiments of the present invention, the mass ratio of the potassium-based manganese ore to the controlled-release agent is 50:(0.1-10); in some embodiments of the present invention, the mass ratio of the potassium-based manganese ore to the controlled-release agent is selected from any one of 50:0.1, 50:0.5, 50:1, 50:1.5, 50:2, 50:2.5, 50:3, 50:3.5, 50:4, 50:4.5, 50:5, 50:5.5, 50:6, 50:6.5, 50:7, 50:7.5, 50:8, 50:8.5, 50:9, 50:9.5, and 50:10, or a range formed by any two of the values.

[0011] In some embodiments of the present invention, the controlled release agent includes 2,6-anthraquinone disulfonic acid and lactate; the mass ratio of the 2,6-anthraquinone disulfonic acid and lactate is 1:(0.1-30); in some embodiments of the present invention, the mass ratio of the 2,6-anthraquinone disulfonic acid and lactate can be any one of 1:0.1, 1:0.5, 1:1, 1:2, 1:4, 1:6, 1:8, 1:10, 1:12, 1:14, 1:16, 1:18, 1:20, 1:22, 1:24, 1:26, 1:28, 1:30 or a range formed by any two of them.

[0012] In some embodiments of the present invention, in the potassium-based manganese ore, the mass percentage of Mn is 20-60%, and the mass percentage of K is 1-10%. In some embodiments of the present invention, in the potassium-based manganese ore, the mass percentage of Mn can be selected from any value of 20%, 30%, 40%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, or a range formed by any two of them. In some embodiments of the present invention, in the potassium-based manganese ore, the mass percentage of K is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a range formed by any two of them.

[0013] In some embodiments of the present invention, the calcite ore has a layered structure.

[0014] In some embodiments of the present invention, the calcite ore is birnessite.

[0015] In some embodiments of the present invention, the increase in potassium in the soil after 9 days of application of the potassium slow-release fertilizer is ≥85 mg / L. In some embodiments of the present invention, the increase in potassium in the soil after 9 days of application of the potassium slow-release fertilizer is 85-2000 mg / L; in some embodiments of the present invention, the increase in potassium in the soil after 9 days of application of the potassium slow-release fertilizer is 85-1000 mg / L; in some embodiments of the present invention, the increase in potassium in the soil after 9 days of application of the potassium slow-release fertilizer is 85-820 mg / L.

[0016] The second aspect of the present invention provides a method for preparing the potassium slow-release fertilizer provided in the first aspect of the present invention, comprising the following steps:

[0017] The potassium slow-release fertilizer is prepared by mixing raw materials including potassium-based manganese ore and a controlled-release agent.

[0018] In some embodiments of the present invention, the potassium-based manganese ore is prepared by a preparation method comprising the following steps: boiling a mixed solution of concentrated hydrochloric acid and potassium permanganate, reacting for 10 to 60 minutes, and then aging at 55 to 65° C. for 10 to 15 hours to obtain the ore.

[0019] In some embodiments of the present invention, the potassium-based manganese ore is prepared by a preparation method comprising the following steps: firstly mixing a manganese salt and a base, then reacting with potassium permanganate, and then aging at 55 to 65° C. for 10 to 15 hours to obtain the potassium-based manganese ore.

[0020] In some embodiments of the present invention, the manganese salt is selected from at least one of manganese chloride, manganese nitrate and manganese sulfate.

[0021] In some embodiments of the present invention, the potassium-based manganese ore is prepared by a preparation method comprising the following steps: firstly mixing potassium permanganate and a manganese salt, then reacting with nitric acid at 65-75° C., and then reacting with a base to obtain the ore.

[0022] In some embodiments of the present invention, the base is selected from at least one of sodium hydroxide and potassium hydroxide.

[0023] The third aspect of the present invention provides the use of the potassium slow-release fertilizer or potassium-based manganese ore provided in the first aspect of the present invention in the field of fertilizers.

[0024] The beneficial effects of the present invention are as follows: the potassium slow-release fertilizer in the present invention loads a controlled-release agent on potassium-based manganese ore, and the controlled-release agent promotes the release of potassium and manganese elements in the potassium-based manganese ore, thereby increasing the potassium and manganese contents in the soil. Specifically, after the potassium slow-release fertilizer is applied to the soil for 9 days, the potassium element can be slowly released by ≥85 mg / L, and when the application amount of the potassium slow-release fertilizer in the soil is increased, the release amount of the potassium element can reach about 800 mg / L.

[0025] In addition, the potassium slow-release fertilizer in the present invention can efficiently release potassium, is suitable for different types of soil, has universality and high efficiency, and its preparation method is simple and easy to operate, the raw material source is wide, it is environmentally friendly, will not cause adverse effects on the original soil, is low in cost, and is easy to promote and apply. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 1 is the X-ray diffraction spectrum of manganese ore 1, manganese ore 2 and manganese ore 3 prepared in Example 1.

[0027] Figure 2 The following are scanning electron microscope images of manganese ore 1, manganese ore 2 and manganese ore 3 prepared in Example 1.

[0028] Figure 3 This is a diagram showing the mechanism of potassium and manganese release from the potassium slow-release fertilizer in Example 2. DETAILED DESCRIPTION

[0029] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. The reagents or instruments used that do not indicate the manufacturer are all conventional products that can be purchased commercially.

[0030] The sodium lactate used in the following examples is L-sodium lactate.

[0031] Example 1

[0032] This example provides a method for preparing a potassium slow-release fertilizer, comprising the following steps:

[0033] (1) Preparation of potassium-based manganese ore

[0034] Preparation of manganese ore 1: 15 mL of concentrated hydrochloric acid solution was added dropwise to 500 mL of potassium permanganate solution with a concentration of 0.4 mol / L, and the mixed solution was heated in an oil bath to be in a boiling state, and magnetic stirring was performed in the oil bath. Subsequently, the mixture was heated for 30 min, and then aged at 60° C. for 720 min to obtain a suspension containing potassium-based manganese ore. The obtained suspension was centrifuged, washed, and dried to obtain potassium-based manganese ore, which was recorded as manganese ore 1. The dried manganese ore 1 was ground through a 100-mesh sieve and stored in a dry environment for later use.

[0035] Preparation of manganese ore 2: 125 mL of 0.3 mol / L MnCl 2 and 250 mL of 0.5 mol / L NaOH at room temperature to obtain a mixed solution; then 125 mL of 0.2 mol / L KMnO 4 The obtained suspension was added dropwise into the above mixed solution, and the obtained suspension was stirred for 30 minutes, and then aged in an oven at 60°C for 720 minutes to obtain a suspension containing potassium-based manganese ore. The obtained suspension was centrifuged, washed, and dried to obtain potassium-based manganese ore, recorded as manganese ore 2. The dried manganese ore 2 was ground through a 100-mesh sieve and stored in a dry environment for later use.

[0036] Preparation of manganese ore 3: 1.58 g potassium permanganate and 1.69 g manganese sulfate monohydrate were dissolved in 70 mL water and stirred for 10 min. Then 15 mL of 10% nitric acid solution was added dropwise and reacted at 70° C. for 120 min. After the reaction was completed, 0.5 g sodium hydroxide was added and stirred for 10 min. The precipitate generated by the reaction was washed with deionized water for 5 times and finally dried at 60° C. for 720 min to obtain potassium-based manganese ore, which was recorded as manganese ore 3. The dried manganese ore 3 was ground through a 100-mesh sieve and stored in a dry environment for later use.

[0037] X-ray diffraction spectrometer was used to characterize manganese ore 1, manganese ore 2 and manganese ore 3 respectively. The specific test results are as follows: Figure 1 As shown. Figure 1 It can be seen that manganese ore 1, manganese ore 2 and manganese ore 3 are all birnessite, among which manganese ore 1 has a better crystal form, while the 001 and 002 crystal planes of manganese ore 2 and manganese ore 3 are very weak.

[0038] The manganese ore 1, manganese ore 2 and manganese ore 3 were tested by scanning electron microscope. The specific test results are as follows: Figure 2 As shown. Figure 2 It can be seen that manganese ore 1, manganese ore 2 and manganese ore 3 all have a flaky structure.

[0039] Inductively coupled plasma atomic emission spectrometry was used to test manganese ore 1, manganese ore 2 and manganese ore 3, respectively, to test the contents (i.e., mass percentages) of Mn and K elements in the three different potassium-based manganese ores. The specific test results are shown in Table 1.

[0040] Table 1 Contents of Mn and K in three different potassium-based manganese ores

[0041] Manganese Ore 1 Manganese Ore 2 Manganese Ore 3 K content 7.2±0.1％ 2.8±0.4％ 1.9±0.1％ Mn content 53.2±1.6％ 51.8±0.9％ 55.5±1.4％

[0042] As shown in Table 1, there are obvious differences in the interlayer potassium ions of manganese ore 1, manganese ore 2, and manganese ore 3, among which manganese ore 1 has a higher potassium content and is more suitable for use as a potassium slow-release fertilizer.

[0043] The effects of three different potassium-based manganese ores prepared by the above method on the release of manganese and potassium in the soil were tested. The specific test methods are as follows:

[0044] 50 mg of three different potassium-based manganese ores (i.e., manganese ore 1, manganese ore 2, and manganese ore 3) were mixed with 1000 mg of soil samples, and shaken in a shaker at 180 r / min for 1 hour to mix the potassium-based manganese ore and soil evenly to obtain a mixed sample. At the same time, the original soil without manganese ore was used as a control. 15 mL of distilled water was added to the mixed sample, which was placed in a 25°C incubator. Samples were taken on the 3rd, 6th, and 9th days of the experiment, and the manganese and potassium content in the aqueous solution was determined by inductively coupled plasma absorption spectroscopy through a 0.22 μm water filter to evaluate the release of manganese and potassium by different potassium-based manganese ores in the soil. The specific test results are shown in Table 2 below.

[0045] Table 2 Test results of manganese and potassium release in soil by different potassium-based manganese ores

[0046]

[0047] As shown in Table 2, manganese ore 1, manganese ore 2 and manganese ore 3 all significantly increased the content of water-soluble potassium in the soil solution, among which manganese ore 1 had a more obvious effect on increasing the potassium content in the soil solution, with the increase reaching about 50 times on the 9th day.

[0048] (2) Loading 2,6-anthraquinone disulfonic acid (AQDS)

[0049] To 50 mg of manganese ore 1, 0 mg, 0.226 mg, and 0.907 mg of 2,6-anthraquinone disulfonic acid were added respectively, and the mixture was shaken at a speed of 180 r / min for 30 min to obtain potassium-based manganese ores loaded with different contents of 2,6-anthraquinone disulfonic acid.

[0050] The potassium manganese ore loaded with different contents of 2,6-anthraquinone disulfonic acid prepared above was mixed with 1000 mg of soil sample respectively, and shaken in a shaker at a speed of 180 r / min for 1 hour to mix the potassium manganese ore and soil evenly to obtain a mixed sample, wherein the original soil was taken as a control. Then 15 mL of distilled water was added to the mixed sample, which was placed in an incubator at 25 ° C. Samples were taken on the 3rd, 6th and 9th days of the experiment, and filtered through a 0.22 μm water filter. The manganese and potassium content in the solution was determined using inductively coupled plasma absorption spectroscopy to evaluate the effect of loading different contents of 2,6-anthraquinone disulfonic acid on the release of manganese and potassium from potassium manganese ore in the soil. The specific test results are shown in Table 3.

[0051] Table 3 shows the test results of potassium-based manganese ore loaded with 2,6-anthraquinone disulfonic acid releasing manganese and potassium in soil

[0052]

[0053] As shown in Table 3, the manganese ore 1 in the present invention significantly increases the potassium content released in the soil after being loaded with 2,6-anthraquinone disulfonic acid. No manganese release was detected during the original soil culture process. After manganese ore 1 was loaded with 0.907 mg of 2,6-anthraquinone disulfonic acid, the manganese content released in the soil was also increased to a certain extent. It can be seen that the addition of 2,6-anthraquinone disulfonic acid and manganese ore 1 to the soil increases the release of potassium.

[0054] Example 2

[0055] This example provides a method for preparing a potassium slow-release fertilizer, comprising the following steps:

[0056] (1) Preparation of potassium-based manganese ore

[0057] Preparation of manganese ore 1: 15 mL of concentrated hydrochloric acid solution was added dropwise to 500 mL of potassium permanganate solution with a concentration of 0.4 mol / L, and the mixed solution was heated in an oil bath to be in a boiling state, and magnetic stirring was performed in the oil bath. Subsequently, the mixture was heated for 30 min, and then aged at 60° C. for 720 min to obtain a suspension containing potassium-based manganese ore. The obtained suspension was centrifuged, washed, and dried to obtain potassium-based manganese ore, which was recorded as manganese ore 1. The dried manganese ore 1 was ground through a 100-mesh sieve and stored in a dry environment for later use.

[0058] (2) Loading sodium lactate

[0059] To 50 mg of manganese ore 1, 0.907 mg of 2,6-anthraquinone disulfonic acid was added, and 0 mg, 2.1 mg, and 5.6 mg of sodium lactate were added respectively, and the mixture was shaken at a speed of 180 r / min for 30 min to obtain 2,6-anthraquinone disulfonic acid modified potassium-based manganese ore loaded with different contents of sodium lactate; then 2.1 mg of sodium lactate was added to 50 mg of manganese ore 1, and potassium-based manganese ore loaded with sodium lactate was prepared in the same way.

[0060] Subsequently, the potassium-based manganese ore loaded with sodium lactate prepared above was mixed with 1000 mg of soil sample respectively, and oscillated in a shaker at a speed of 180 r / min for 1 hour to mix the potassium-based manganese ore and soil evenly to obtain mixed samples, which were respectively recorded as: Sample 1 (0.907 mg of AQDS and 0 mg of sodium lactate were loaded on manganese ore 1), Sample 2 (only 2.1 mg of sodium lactate was loaded on manganese ore 1), Sample 3 (0.907 mg of AQDS and 2.1 mg of sodium lactate were loaded on manganese ore 1), and Sample 4 (0.907 mg of AQDS and 5.6 mg of sodium lactate were loaded on manganese ore 1). Then, 15 mL of distilled water was added to the mixed samples, and the samples were placed in an incubator at 25 °C. Samples were taken on the 3rd, 6th and 9th days of the experiment, and the manganese and potassium contents in the solutions were determined by inductively coupled plasma absorption spectroscopy. The effects of different loading levels of sodium lactate on the release of manganese and potassium from potassium-based manganese ore in the soil were evaluated. The specific test results are shown in Table 4.

[0061] Table 4 shows the test results of potassium-based manganese ore loaded with 2,6-anthraquinone disulfonic acid and sodium lactate releasing manganese and potassium in soil

[0062]

[0063] By comparing sample 2 and sample 3-4 in Table 4, it can be seen that the potassium-based manganese ore of the present invention can significantly increase the release of potassium in the soil after loading 2,6-anthraquinone disulfonic acid; by comparing sample 1 and sample 3-4 in Table 4, it can be seen that the potassium-based manganese ore 1 of the present invention can simultaneously increase the content of manganese and potassium in the soil after loading sodium lactate, indicating that sodium lactate increases the reduction and dissolution of manganese in the stable potassium-based manganese ore, promotes the release of potassium ions between the potassium-based manganese ore structure layers, and increases the potassium content released by the potassium-based manganese ore in the soil, which not only greatly increases the release of the nutrient element potassium, but also significantly increases the manganese content. Manganese is one of the important trace nutrients in the soil and has many effects on plant growth and soil health.

[0064] The mechanism of potassium slow-release fertilizer in this example releasing potassium and manganese in the soil is shown in the figure below: Figure 3 The specific analysis is as follows:

[0065] 2,6-Anthraquinone disulfonic acid mainly acts as a redox medium in the reduction and dissolution process of potassium manganese ore. It can accept electrons (microorganisms or reducing substances) and transfer them to the surface of potassium manganese ore, thereby promoting the reduction reaction of potassium manganese ore. Therefore, 2,6-Anthraquinone disulfonic acid promotes the reduction and dissolution of manganese in the potassium manganese ore with stable structure, releases potassium ions between the potassium manganese ore structure layers, and increases the potassium content released by potassium manganese ore in the soil. The reaction mechanism can be described as follows:

[0066] AQDS+2H + +2e - →AQDSH2

[0067] AQDS (oxidized state, quinone form) accepts electrons and is reduced to the hydroquinone form (AQDSH 2 )

[0068] K-MnO 2 +AQDSH 2 →K + +MnO 2 / Mn 3+ / Mn 2+ +AQDS+H 2 O

[0069] AQDSH 2 Transfer electrons to K-MnO 2 , triggering the reduction reaction of manganese oxide, K + From K-MnO 2 Detachment from the layered structure.

[0070] The reaction mechanism of sodium lactate promoting the release of manganese is described as follows:

[0071] C 3 H 5 O 3 - →C 3 H 4 O 3 +2H + +2e -

[0072] Lactate ion (C 3 H 5 O 3 - ) undergoes oxidation reaction in the solution to generate pyruvic acid (C 3 H 4 O 3 ) and release electrons.

[0073] K-MnO 2 +e - +H + →K + +MnO 2 / Mn 3+ / Mn 2+

[0074] The electrons donated by sodium lactate are 2 Accept, trigger K-MnO 2 The reduction dissolution releases K from the structure.

[0075] K-MnO 2 +C 3 H5 O 3 - + Microorganisms → K + +MnO 2 / Mn 3+ / Mn 2+

[0076] At the same time, sodium lactate promotes the reduction of microorganisms by acting as an electron donor, and also improves the dissolution efficiency of potassium-based manganese ore and K + Release efficiency.

[0077] In order to study the effect of potassium-based manganese ore loaded with potassium-based manganese ore and sodium lactate on the release of manganese and potassium from different soils, the following experiments were conducted:

[0078] 0.907 mg of 2,6-anthraquinone disulfonic acid and 5.6 mg of sodium lactate were added to 50 mg of manganese ore 1, and the mixture was shaken at a speed of 180 r / min for 30 min to obtain a modified potassium-based manganese ore loaded with sodium lactate and 2,6-anthraquinone disulfonic acid, which is the potassium slow-release fertilizer in this example.

[0079] Subsequently, the potassium-based slow-release fertilizer was mixed with 1000 mg of rice soil, grassland soil, and vegetable soil samples, respectively, and shaken in a shaker at 180 r / min for 1 hour to evenly mix the potassium-based manganese ore with the soil to obtain a mixed sample. Then, 15 mL of distilled water was added to the mixed sample, which was placed in an incubator at 25°C. Samples were taken on the 3rd, 6th, and 9th days of the experiment, and filtered through a 0.22 μm water filter. Inductively coupled plasma absorption spectroscopy was used to determine the manganese and potassium content in the solution to evaluate the effect of potassium-based manganese ore on the release of manganese and potassium in different types of soils. The specific test results are shown in Table 5.

[0080] Table 5 shows the test results of potassium-based manganese ore releasing manganese and potassium in different types of soil

[0081]

[0082]

[0083] As can be seen from Table 5, the manganese ore 1 in the present invention significantly increases the content of manganese and potassium released in paddy soil, grassland soil, and vegetable soil after being loaded with 2,6-anthraquinone disulfonic acid and sodium lactate, further indicating that the potassium slow-release fertilizer in the present invention is suitable for a variety of soil types, and has wide applicability and high application value. Paddy soil is a flooded soil, and soil particles and manganese ore will undergo reduction and dissolution under chemical and biological effects. If potassium-rich manganese ore 1 is applied to flooded soil, manganese ore 1 can be slowly reduced and dissolved accompanied by the release of potassium in the structure, thereby achieving the slow release of potassium nutrients in a flooded environment and promoting the healthy growth of crops.

[0084] In order to study the effect of potassium-based manganese ore application on the release of manganese and potassium in the soil, the following experiments were conducted:

[0085] 0.907 mg of 2,6-anthraquinone disulfonic acid and 5.6 mg of sodium lactate were added to 50 mg, 100 mg, and 200 mg of potassium manganese ore 1, respectively, and the mixture was shaken at a speed of 180 r / min for 30 min to obtain potassium manganese ore modified with sodium lactate and 2,6-anthraquinone disulfonic acid. Then, the mixture was mixed with 1000 mg of soil sample, shaken in a shaker at a speed of 180 r / min for 1 h, and the potassium manganese ore and soil were evenly mixed to obtain a mixed sample. Then, 15 mL of distilled water was added to the mixed sample, which was placed in a 25 ° C incubator. Samples were taken on the 3rd, 6th, and 9th days of the experiment, and filtered through a 0.22 μm water filter. The manganese and potassium content in the solution was determined by inductively coupled plasma absorption spectroscopy to evaluate the effect of potassium manganese ore application on the release of manganese and potassium in the soil. The specific test results are shown in Table 6.

[0086] Table 6 shows the test results of the release of manganese and potassium in the soil by the amount of potassium-based manganese ore applied

[0087]

[0088] It can be seen from Table 6 that with the increase in the application amount of potassium-based manganese ore in the present invention, the manganese and potassium contents in the soil solution are significantly increased. However, for cost-effectiveness considerations, the application amount of potassium-based manganese ore needs to be comprehensively evaluated in practical applications.

[0089] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A potassium slow-release fertilizer, characterized in that: The invention comprises potassium-based manganese ore and a controlled-release agent loaded on the potassium-based manganese ore; the controlled-release agent comprises at least one of 2,6-anthraquinone disulfonic acid and lactate.

2. The potassium slow-release fertilizer according to claim 1, characterized in that: The mass ratio of the potassium-based manganese ore to the controlled release agent is 50: (0.1～10)。 3. The potassium slow-release fertilizer according to claim 1, characterized in that: The controlled release agent includes 2,6-anthraquinone disulfonic acid and lactate; The mass ratio of the 2,6-anthraquinone disulfonic acid to the lactate is 1:(0.1-30).

4. The potassium slow-release fertilizer according to claim 1, characterized in that: In the potassium-based manganese ore, the mass percentage of Mn is 20-60%, and the mass percentage of K is 1-10%.

5. The potassium slow-release fertilizer according to claim 1, characterized in that: The potassium-based manganese ore has a layered structure.

6. The potassium slow-release fertilizer according to claim 1, characterized in that: The potassium-based manganese ore is birnessite.

7. The potassium slow-release fertilizer according to any one of claims 1 to 6, characterized in that: After the potassium slow-release fertilizer is applied for 9 days, the increase in potassium in the soil is ≥85 mg / L.

8. The method for preparing the potassium slow-release fertilizer according to any one of claims 1 to 7, characterized in that: The following steps are involved: The potassium slow-release fertilizer is prepared by mixing raw materials including potassium-based manganese ore and a controlled-release agent.

9. The method for preparing the potassium slow-release fertilizer according to claim 8, characterized in that: The potassium-based manganese ore is prepared by a preparation method comprising the following steps: boiling a mixed solution of concentrated hydrochloric acid and potassium permanganate, reacting for 10 to 60 minutes, and then aging at 55 to 65° C. for 10 to 15 hours to obtain the potassium-based manganese ore; Alternatively, the potassium-based manganese ore is prepared by a preparation method comprising the following steps: firstly mixing a manganese salt and an alkali, then reacting with potassium permanganate, and then aging at 55 to 65° C. for 10 to 15 hours to obtain the potassium-based manganese ore; Alternatively, the potassium-based manganese ore is prepared by a preparation method comprising the following steps: firstly, potassium permanganate and a manganese salt are mixed, then reacted with nitric acid at 65-75° C., and then reacted with an alkali to obtain the potassium-based manganese ore.

10. Use of the potassium slow-release fertilizer or potassium-based manganese ore according to any one of claims 1 to 7 in the field of fertilizers.

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