A multi-element nutrient loaded manganese ore slow-release fertilizer, a preparation method and application thereof

Abstract

The application discloses a kind of multi-element nutrient element load type manganese ore slow-release fertilizer and its preparation method and application;The slow-release fertilizer includes modified manganese ore, nutrient element and lignin;Nutrient element is loaded in the modified manganese ore.This application is prepared by loading nutrient element on manganese ore, thereby preparing fertilizer that can slowly release nutrient element into soil, can significantly improve the content of nutrient element (including manganese, potassium, iron, calcium, copper, zinc) in soil after applying the fertilizer to soil, specifically: manganese, zinc, copper in soil can be increased from 0 mg / L to 7.93-121.9 mg / L, 0.02-0.70 mg / L, 0.00-0.66 mg / L respectively, while the concentration of iron, potassium and calcium in soil is increased by 122.8 times, 10.73 times and 5.32 times respectively.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of fertilizers, and particularly relates to a multi-element nutrient element loaded manganese ore slow-release fertilizer as well as a preparation method and application thereof. BACKGROUND

[0002] Manganese ore is commonly used in metallurgy, batteries, chemical industry and environmental pollution remediation fields, and the application of manganese ore in agricultural production is still very scarce. Manganese is an essential nutrient element for plant growth, participates in photosynthesis and respiration, and promotes crop growth and improves yield. Therefore, manganese element plays an important role in plant growth and yield improvement. In the past, manganese, potassium, calcium, zinc, copper and iron nutrients were often directly applied to the soil in the form of inorganic salts, which easily led to excessive accumulation of nutrient elements in the soil, thereby causing adverse effects on the environment and crop health. Slow-release fertilizer is a fertilizer used for gradually releasing nutrient elements within a certain period of time, which can improve fertilizer utilization rate, reduce nutrient loss, stabilize plant growth, and reduce the impact on the environment. However, traditional slow-release fertilizers rely on petroleum-based polymers (such as polyurethane and polyethylene) for coating, and the raw materials are non-renewable and expensive, and microplastic pollution (such as PBAT slow-release film residue problem) is generated after degradation. Most slow-release fertilizers are designed only for single elements such as nitrogen, phosphorus and potassium, and cannot meet the demand for the coordinated release of manganese, zinc, iron and other trace elements. In addition, the existing slow-release fertilizers have high cost, cannot realize the loading and slow release of multiple elements, and have limited slow-release effect when applied to the soil, which cannot meet the growth demand of crops. SUMMARY

[0003] In order to overcome at least one technical problem existing in the prior art, one of the purposes of the present application is to provide a slow-release fertilizer, which is a nutrient element carrier with a stable structure of manganese ore, and the nutrient elements are loaded in the tunnels and interlayers of the manganese ore to avoid excessive content of the nutrient elements caused by too fast release; then the release of the nutrient elements in the manganese ore is regulated by lignin, which can realize slow and continuous release of the nutrient elements and provide effective state nutrient elements for plants.

[0004] The second purpose of the present application is to provide a preparation method of the slow-release fertilizer.

[0005] The third purpose of the present application is to provide the application of the slow-release fertilizer in the field of fertilizers.

[0006] In order to achieve the above purposes, the technical scheme adopted by the present application is as follows:

[0007] The present application provides a slow-release fertilizer, which comprises modified manganese ore, nutrient elements and lignin; the modified manganese ore is loaded with nutrient elements.

[0008] The manganese ore can adopt various structures such as todorokite, pyrolusite, and calcium manganese ore, and has rich ion exchange sites in tunnels and interlayers, and can be used as a storage of metal nutrient elements such as potassium, calcium, zinc, copper and iron. The modified manganese ore is loaded with metal elements, so that the metal elements are loaded in the tunnels and interlayers of the manganese ore, the content and type of nutrient elements in the manganese ore are controlled according to the needs of the soil, the nutrient elements loaded in the slow-release fertilizer can be slowly released into the soil, the growth and development needs of plants are met, and the over-accumulation of nutrient elements in the soil is avoided, so that the growth of plants is not adversely affected.

[0009] In addition, the manganese ore has an octahedral isomorphic structure, manganese forms a coordination bond with surrounding ligand oxygen, and is relatively stable in nature. After the manganese ore is modified and loaded with metal elements, the metal elements can be stored in the tunnels and interlayers of the manganese ore, exist in the form of ion exchange or hydrated ions, or are inlaid in the crystal cell of the manganese ore, and are relatively stable and not easy to release. Then the lignin promotes the release of the nutrient elements loaded in the tunnels and interlayers of the manganese ore, and the content of the nutrient elements in the soil is improved, the nutrient elements can be continuously provided during the growth cycle of crops, the frequency of fertilization is reduced, and the negative impact on the environment is reduced. It is an environmentally friendly and economically significant agricultural technology.

[0010] In some embodiments of the present application, the nutrient elements include at least one of iron, manganese, zinc, copper, potassium and calcium.

[0011] In some embodiments of the present application, the mass ratio of the manganese ore to the lignin is 5:(3-4); in some embodiments of the present application, the mass ratio of the manganese ore to the lignin can be selected from any one of 5:3.0, 5:3.1, 5:3.2, 5:3.3, 5:3.4, 5:3.5, 5:3.6, 5:3.7, 5:3.8, 5:3.9, 5:4.0 or a range value formed by any two thereof.

[0012] In some embodiments of the present application, the modified manganese ore is a manganese ore modified by an alkali metal borohydride.

[0013] In some embodiments of the present application, the mass ratio of the manganese ore to the alkali metal borohydride is 50:(0.5-1.5); in some embodiments of the present application, the mass ratio of the manganese ore to the alkali metal borohydride is any one of 50:0.5, 50:0.6, 50:0.7, 50:0.8, 50:0.9, 50:1.0, 50:1.1, 50:1.2, 50:1.3, 50:1.4, 50:1.5 or a range value formed by any two thereof.

[0014] In some embodiments of the present invention, the specific surface area of ​​the manganese ore is 20–30 m². 2 / g; In some embodiments of the present invention, the specific surface area of ​​the manganese ore is 20m². 2 / g、21m 2 / g、22m 2 / g、23m 2 / g、24m 2 / g、25m 2 / g、26m 2 / g、27m 2 / g、28m 2 / g、29m 2 / g、30m 2 Any value in / g or a range of values ​​formed by either or both.

[0015] In some embodiments of the present invention, the manganese ore has a porous structure.

[0016] In some embodiments of the present invention, the pore volume of the manganese ore is 0.06–0.07 cm³. 3 / g; In some embodiments of the present invention, the pore volume of the manganese ore is 0.06 cm³. 3 / g, 0.061cm 3 / g, 0.062cm 3 / g, 0.063cm 3 / g, 0.064cm 3 / g, 0.065cm 3 / g, 0.066cm 3 / g, 0.067cm 3 / g, 0.068cm 3 / g, 0.069cm 3 / g, 0.07cm 3 Any value in / g or a range of values ​​formed by either or both.

[0017] In some embodiments of the present invention, the average pore diameter of the manganese ore is 10-15 nm; in some embodiments of the present invention, the average pore diameter of the manganese ore is any value of 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, or a range formed by any two of these values.

[0018] In some embodiments of the present invention, the manganese ore comprises platy manganese ore.

[0019] In some embodiments of the present invention, the manganese ore is natural manganese ore.

[0020] The second aspect of the present invention provides a method for preparing the slow-release fertilizer described in the first aspect of the present invention, comprising the following steps:

[0021] The slow-release fertilizer is prepared by reacting manganese ore sequentially with alkali metal borohydrides, metal salts, and lignin.

[0022] In some embodiments of the present invention, the mixing reaction is carried out using an oscillator.

[0023] In some embodiments of the present invention, the mixing reaction time is 1 to 24 hours; in some embodiments of the present invention, the mixing reaction time is any value or a range formed by any two of the following: 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, and 24 hours.

[0024] In some embodiments of the present invention, the temperature of the mixing reaction is 20–40°C; in some embodiments of the present invention, the temperature of the mixing reaction is any value or a range formed by any combination of 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, and 40°C.

[0025] In some embodiments of the present invention, the metal salt includes at least one selected from potassium salt, iron salt, calcium salt, copper salt, and zinc salt.

[0026] The third aspect of the present invention provides the application of the slow-release fertilizer described in the first aspect of the present invention in the field of fertilizers.

[0027] The beneficial effects of this invention are as follows: By loading nutrients onto manganese ore, this invention prepares a fertilizer that loads nutrients and can slowly release them into the soil. When applied to the soil, this fertilizer can significantly increase the content of nutrients (including manganese, potassium, iron, calcium, copper, and zinc) in the soil. Specifically, the concentrations of manganese, zinc, and copper in the soil can increase from 0 mg / L to 7.93–121.9 mg / L, 0.02–0.70 mg / L, and 0.00–0.66 mg / L, respectively, while the concentrations of iron, potassium, and calcium in the soil increase by 122.8 times, 10.73 times, and 5.32 times, respectively. Furthermore, the slow-release fertilizer of this invention is safe, environmentally friendly, and will not cause adverse effects on the environment. It can simultaneously meet the supply and slow release of multiple nutrients, possessing universality and high efficiency, and can meet the needs of soils deficient in different or multiple elements.

[0028] The preparation method of this invention uses manganese ore as a base and sequentially processes it through alkali metal borohydride, metal salt, and lignin modification to prepare a slow-release fertilizer that can increase the release of soil nutrients and release them slowly. This preparation method is simple, easy to operate, uses widely available and inexpensive raw materials, and has mild preparation conditions, making it suitable for large-scale industrial production. Attached Figure Description

[0029] Figure 1 The image shows the XRD diffraction pattern of the natural manganese ore in Example 1.

[0030] Figure 2 This is a scanning electron microscope image of the natural manganese ore in Example 1.

[0031] Figure 3 This is a nitrogen adsorption curve of the natural manganese ore in Example 1.

[0032] Figure 4 This is a particle size distribution diagram of the natural manganese ore in Example 1.

[0033] Figure 5 This is a flowchart of the preparation process of natural manganese ore in Example 6. Detailed Implementation

[0034] The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described in detail below are those that can be implemented or understood by those skilled in the art by referring to the prior art. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0035] Example 1

[0036] This example provides a method for preparing a supported manganese ore slow-release fertilizer, which specifically includes the following steps:

[0037] S1. Pretreatment and characterization of natural manganese ore:

[0038] The natural manganese ore used in this example was collected from Leiyang, Hunan Province. Three types of natural manganese ore samples were collected, denoted as: Natural Manganese Ore 1, Natural Manganese Ore 2, and Natural Manganese Ore 3. After impurity removal, washing, and grinding, they were passed through a 100-mesh sieve. The elemental composition of the three types of natural manganese ore was analyzed using X-ray fluorescence spectroscopy, as shown in Table 1 below.

[0039] Table 1. Mass fraction of each element in three types of natural manganese ores

[0040] O Mn Fe Si Al K Ca Natural manganese ore 1 42.55％ 15.24％ 13.56％ 20.64％ 5.04％ 0.40％ 0.12％ Natural manganese ore 2 41.05％ 21.26％ 16.01％ 17.31％ 2.45％ 0.39％ 0.19％ Natural manganese ore 3 40.43％ 23.32％ 16.14％ 15.87％ 2.28％ 0.41％ 0.20％

[0041] As shown in Table 1, all three types of natural manganese ore contain high levels of manganese and iron. However, the manganese and iron content in natural manganese ore 3 is significantly higher than that in the other two types of natural manganese ore (i.e., natural manganese ore 1 and natural manganese ore 2). This invention mainly utilizes the slow dissolution of iron and manganese, two transition metal elements in natural minerals, in the soil to release the elements and their complex elements in the minerals. Therefore, in this example and the following embodiments, natural manganese ore 3, which has a higher iron and manganese content, was selected. In addition, the potassium and calcium content in natural manganese ore 3 is also relatively high. The natural manganese ore mentioned in the following embodiments refers to natural manganese ore 3.

[0042] Then, X-ray diffraction spectroscopy was used to identify the phase composition of the natural manganese ore. Specific test images are shown below. Figure 1 As shown. By Figure 1 It can be seen that the natural manganese ore used in this example is composed of quartz, goethite, manganese oxide, and pyrolusite. The surface morphology of the natural manganese ore was examined using scanning electron microscopy, as shown in the following figures. Figure 2 As shown, where, Figure 2 (a) and Figure 2 (b) shows SEM images of natural manganese ore at scales of 1 μm and 200 nm, respectively. Figure 2 It is known that natural manganese ore mainly exists in two forms: platy and acicular. Platy ore is quartz, as well as calcium manganese ore and lithium manganese ore, while acicular ore is goethite.

[0043] The nitrogen adsorption-desorption curves and pore size of natural manganese ore were tested using a fully automated surface area and porosity analyzer (BET). Specifically, the results are as follows: Figure 3 and Figure 4 As shown. By Figure 3 and Figure 4 It can be seen that the specific surface area of ​​natural manganese ore is 24.0 m². 2 / g, average pore volume is 0.064cm³ 3 / g, with an average pore diameter of 11.07nm, the manganese ore used has a large specific surface area and abundant pore size.

[0044] S2: Preparation of potassium-supported natural manganese ore:

[0045] 500 mg of natural manganese ore was added to 40 mL of potassium borohydride solutions with concentrations of 1.25 mol / L, 2.5 mol / L, and 5 mol / L, respectively. After shaking on a shaker for 3 h, the mixture was filtered, washed, and dried to obtain manganese ore 1, manganese ore 2, and manganese ore 3, respectively. 40 mL of potassium chloride solution with a concentration of 0.1 mol / L was added to each of the natural manganese ore, manganese ore 1, manganese ore 2, and manganese ore 3, respectively. After shaking on a shaker for 10 h, the mixture was filtered, washed, and dried to obtain potassium-based manganese ore 1 (without potassium borohydride treatment), potassium-based manganese ore 2, potassium-based manganese ore 3, and potassium-based manganese ore 4, respectively.

[0046] The effects of various manganese ores on the content of manganese, potassium, iron, and calcium in flooded paddy soil were tested. The specific testing methods are as follows:

[0047] Paddy soil samples were collected from Zhishan, Jiangmen. After impurities were removed, the soil was ground through a 60-mesh sieve and added to 20 mL glass bottles. 15 mL of water was added to submerge the soil. Subsequently, 5% (by weight) of natural manganese ore, potassium-based manganese ore 1, potassium-based manganese ore 2, potassium-based manganese ore 3, and potassium-based manganese ore 4 were added to the paddy soil samples. The mixture was shaken for 5 minutes to ensure homogeneity, and then incubated at 25℃. On days 3, 6, and 9, the soil suspension was filtered through a 0.22 μm filter to determine the manganese, iron, and potassium content, evaluating the effects of each manganese ore on the manganese, potassium, and iron nutrient content in the soil. A blank submerged paddy soil sample was used as a control. Specific test results are shown in Table 2 below.

[0048] Table 2. Results of tests on the effects of various manganese ores on the nutrient content of flooded paddy soil.

[0049]

[0050] Table 2 shows that, compared with natural manganese ore, loading potassium onto natural manganese ore (with or without potassium borohydride treatment) did not significantly increase the manganese, iron, and calcium contents in the soil. Nine days after application, the manganese, iron, and calcium contents in the soil were 0.00 mg / L, 0.15–0.17 mg / L, and 6.29–8.04 mg / L, respectively. The potassium contents of the original soil after 3, 6, and 9 days of incubation were 1.45 ± 0.00 mg / L, 1.65 ± 0.01 mg / L, and 1.73 ± 0.01 mg / L, respectively. After 3, 6, and 9 days of incubation with natural manganese ore, the potassium contents were 1.68 ± 0.03 mg / L, 1.72 ± 0.37 mg / L, and 1.74 ± 0.04 mg / L, respectively. Therefore, directly applying natural manganese ore to the soil did not change the potassium content in the soil. Potassium-based manganese ore 1, obtained by potassium ion exchange of natural manganese ore, was applied to soil. After 3, 6, and 9 days of cultivation, the potassium content was 2.05±0.00 mg / L, 2.19±0.03 mg / L, and 2.55±0.11 mg / L, respectively, showing a certain increase in potassium release compared to direct application of natural manganese ore. Furthermore, natural manganese ore was treated with 1.25 mol / L, 2.5 mol / L, and 5 mol / L potassium borohydride solutions to obtain manganese ore 1, 2, and 3, respectively. These were then subjected to potassium ion exchange to obtain potassium-based manganese ore 2, 3, and 4. When potassium-based manganese ore 2, 3, and 4 were applied to soil and cultivated for 9 days, the potassium content was 2.85±0.08 mg / L, 2.96±0.03 mg / L, and 3.31±0.15 mg / L, respectively, indicating a significant increase in soil potassium content. Potassium borohydride treatment can significantly enhance the potassium-enhancing effect of obtained potassium-based manganese ore on soil potassium content. When potassium borohydride reacts with natural manganese ore, its strong reducing properties disrupt the crystal structure of the natural manganese ore, generating more defect structures. These defect structures increase the specific surface area and active sites of the natural manganese ore, thus facilitating the adsorption and fixation of potassium ions. Therefore, the higher the dosage of potassium borohydride, the more defect structures are generated, the stronger the adsorption capacity for potassium ions, and consequently, the more significant the increase in soil potassium content.

[0051] S3. Preparation of supported manganese ore slow-release fertilizer:

[0052] Potassium-based manganese ore 4 was mixed with 75 mg and 375 mg of lignin, respectively, to obtain potassium-based manganese ore-lignin 1 and potassium-based manganese ore-lignin 2, namely, supported manganese ore slow-release fertilizer.

[0053] Potassium manganese ore-lignin 1 and potassium manganese ore-lignin 2 were added to paddy soil samples, respectively. On the 3rd, 6th and 9th days of the experiment, the soil suspension was filtered through a 0.22 μm filter to evaluate the effect of lignin application on potassium manganese ore 4 in increasing the content of manganese, potassium, iron and calcium nutrients in the soil. The specific test results are shown in Table 3 below.

[0054] Table 3. Test results of the effect of lignin addition on the enhancement of soil nutrients by potassium-based manganese ore 4.

[0055]

[0056] Table 3 shows that adding lignin to potassium-based manganese ore 4 significantly increases the release of nutrients (including manganese, iron, potassium, and calcium) in the soil. Specific analysis is as follows: Comparing potassium-based manganese ore-lignin 1 and potassium-based manganese ore-lignin 2, it is evident that lignin application effectively enhances manganese release, and the greater the amount of lignin applied, the higher the manganese release. The contents of other elements such as iron, potassium, and calcium also significantly increase. Compared to the original paddy soil, after applying potassium-based manganese ore-lignin 2, the contents of potassium, iron, and calcium in the soil increased by 9.86–10.73, 34.80–75.13, and 4.66–5.03 times, respectively.

[0057] In this invention, the organic acids and phenolic compounds produced by lignin decomposition can be utilized by soil microorganisms as carbon sources and electron donors, promoting microbial growth and metabolism. Microorganisms (such as sulfate-reducing bacteria and iron-reducing bacteria) reduce high-valence metal ions in the soil to lower valence states through respiration. Simultaneously, lignin can directly participate in the reduction and dissolution process of potassium-based manganese ore as a reducing agent. This invention, by adding lignin to potassium-based manganese ore, promotes the reduction and dissolution of manganese and iron and the destruction of their structure, releasing nutrients such as potassium and calcium. Potassium-based manganese ore also undergoes significant reduction and dissolution under the action of lignin, releasing nutrients from the ore itself and its surface. The relevant mechanism is as follows:

[0058] Natural manganese ore (K, Mn, Fe, Ca) + lignin + soil → K, Mn, Fe, Ca (K + Ca 2+ Fe 3+ Zn 2+ Cu 2+ Loading manganese ore + lignin + soil → Mn, Fe, K + Ca 2+ Fe 3+ Zn 2+ Cu 2+

[0059] Example 2

[0060] This example provides a method for preparing a supported manganese ore slow-release fertilizer, which specifically includes the following steps:

[0061] S1. Pretreatment of natural manganese ore:

[0062] The natural manganese ore used in this example was mined in Leiyang, Hunan Province, and after impurity removal, washing, and grinding, it passed through a 100-mesh sieve.

[0063] S2: Preparation of calcium-loaded natural manganese ore:

[0064] 500 mg of natural manganese ore was added to 40 mL of a 5 mol / L potassium borohydride solution, shaken on a shaker for 3 h, filtered and washed, then added to 40 mL of a 0.1 mol / L calcium chloride solution, shaken again on a shaker for 10 h, filtered and washed, and dried to obtain calcium-loaded manganese ore, i.e., calcium-based manganese ore.

[0065] S3: Preparation of supported manganese ore slow-release fertilizer:

[0066] The obtained calcium-based manganese ore was mixed with 375 mg of lignin to prepare the loaded manganese ore slow-release fertilizer in this example.

[0067] The loaded manganese ore slow-release fertilizer in this example was added to the flooded paddy soil, and then a culture experiment was carried out. On the 3rd, 6th and 9th days, the soil suspension was filtered through a 0.22 μm filter to evaluate the effect of calcium-based manganese ore on the content of manganese, potassium, iron and calcium nutrients. The specific test results are shown in Table 4.

[0068] Table 4 shows the test results of this example on the effect of increasing calcium in the soil.

[0069]

[0070] As shown in Table 4, this example not only significantly increased the calcium content in the soil by loading calcium into natural manganese ore, but also significantly increased the content of iron, potassium and manganese in the soil. Compared with the blank paddy soil, the slow-release fertilizer in this example increased the calcium content in the soil by more than 4 times.

[0071] Example 3

[0072] This example provides a method for preparing a supported manganese ore slow-release fertilizer, which specifically includes the following steps:

[0073] S1. Pretreatment of natural manganese ore:

[0074] The natural manganese ore used in this example was mined in Leiyang, Hunan Province, and after impurity removal, washing, and grinding, it passed through a 100-mesh sieve.

[0075] S2: Preparation of zinc-supported natural manganese ore:

[0076] 500 mg of manganese ore was added to 40 mL of a 5 mol / L potassium borohydride solution, shaken on a shaker for 3 h, filtered and washed, then added to 40 mL of a 0.1 mol / L zinc chloride solution, shaken on a shaker again for 10 h, filtered and washed, and dried to obtain zinc-loaded manganese ore.

[0077] S3: Preparation of supported manganese ore slow-release fertilizer:

[0078] The zinc-loaded manganese ore was mixed with 375 mg of lignin to prepare the loaded manganese ore slow-release fertilizer in this example.

[0079] The loaded manganese ore slow-release fertilizer in this example was added to the flooded paddy soil, and then a culture experiment was conducted. On the 3rd, 6th and 9th days, the soil suspension was filtered through a 0.22 μm filter to evaluate the effect of the loaded manganese ore slow-release fertilizer on the content of manganese, potassium, iron, calcium and zinc nutrients. The specific test results are shown in Table 5.

[0080] Table 5 shows the test results of this example on the effect of increasing zinc levels in soil.

[0081]

[0082] As shown in Table 5, this example demonstrates that loading zinc onto natural manganese ore significantly increases the content of calcium, manganese, potassium, zinc, and iron in the soil. In contrast, no zinc was detected in the blank soil during the cultivation process. Therefore, loading zinc onto natural manganese ore in this example can significantly increase the zinc content in the soil solution.

[0083] Example 4

[0084] This example provides a method for preparing a supported manganese ore slow-release fertilizer, which specifically includes the following steps:

[0085] S1. Pretreatment of natural manganese ore:

[0086] The natural manganese ore used in this example was mined in Leiyang, Hunan Province, and after impurity removal, washing, and grinding, it passed through a 100-mesh sieve.

[0087] S2: Preparation of copper-supported natural manganese ore:

[0088] 500 mg of manganese ore was added to 40 mL of a 5 mol / L potassium borohydride solution, shaken on a shaker for 3 h, filtered and washed, then added to 40 mL of a 0.1 mol / L copper chloride solution, shaken on a shaker again for 10 h, filtered and washed, and dried to obtain copper-loaded manganese ore.

[0089] S3: Preparation of supported manganese ore slow-release fertilizer:

[0090] The copper-loaded manganese ore was mixed with 375 mg of lignin to prepare the loaded manganese ore slow-release fertilizer in this example.

[0091] The loaded manganese ore slow-release fertilizer in this example was added to the flooded paddy soil, and then a culture experiment was conducted. On the 3rd, 6th and 9th days, the soil suspension was filtered through a 0.22 μm filter to evaluate the effect of the loaded manganese ore slow-release fertilizer on the content of manganese, potassium, iron, calcium and copper nutrients. The specific test results are shown in Table 6.

[0092] Table 6 shows the test results of the effect of this example on increasing copper levels in soil.

[0093]

[0094] As shown in Table 6, this example demonstrates that loading copper onto natural manganese ore significantly increases the content of calcium, manganese, potassium, copper, and iron in the soil. Copper was not detected in the blank soil during the cultivation process. Therefore, loading copper onto natural manganese ore in this example can significantly increase the copper content in the soil solution.

[0095] Example 5

[0096] This example provides a method for preparing a supported manganese ore slow-release fertilizer, which specifically includes the following steps:

[0097] S1. Pretreatment of natural manganese ore:

[0098] The natural manganese ore used in this example was mined in Leiyang, Hunan Province, and after impurity removal, washing, and grinding, it passed through a 100-mesh sieve.

[0099] S2: Preparation of iron-loaded natural manganese ore:

[0100] 500 mg of manganese ore was added to 40 mL of a 5 mol / L potassium borohydride solution, shaken on a shaker for 3 h, filtered and washed, then added to 40 mL of a 0.1 mol / L ferric chloride solution, shaken on a shaker again for 10 h, filtered and washed, and dried to obtain iron-loaded manganese ore.

[0101] S3: Preparation of supported manganese ore slow-release fertilizer:

[0102] The iron-loaded manganese ore was mixed with 375 mg of lignin to prepare the iron-loaded manganese ore slow-release fertilizer in this example.

[0103] The loaded manganese ore slow-release fertilizer in this example was added to the flooded paddy soil, and then a culture experiment was conducted. On the 3rd, 6th and 9th days, the soil suspension was filtered through a 0.22 μm filter to evaluate the effect of the loaded manganese ore slow-release fertilizer on the content of manganese, potassium, iron and calcium nutrients. The specific test results are shown in Table 7.

[0104] Table 7 shows the test results of this example on the effect of increasing iron content in soil.

[0105]

[0106] As shown in Table 7, this example demonstrates that by loading iron into natural manganese ore, the content of calcium, manganese, potassium, and iron in the soil can be significantly increased. Compared with the blank paddy soil, the iron content in the soil after applying the slow-release fertilizer in this example increased by 46.1 to 122.8 times, which is also significantly higher than the iron content in the soil treated with slow-release fertilizer in other examples.

[0107] Example 6

[0108] This example provides a method for preparing a supported manganese ore slow-release fertilizer, which specifically includes the following steps:

[0109] S1. Pretreatment of natural manganese ore:

[0110] The natural manganese ore used in this example was mined in Leiyang, Hunan Province, and after impurity removal, washing, and grinding, it passed through a 100-mesh sieve.

[0111] S2: Preparation of natural manganese ore loaded with multiple nutrients:

[0112] 500 mg of manganese ore was added to 40 mL of a 5 mol / L potassium borohydride solution. After shaking on a shaker for 3 h, the mixture was filtered and washed. Then, it was added to 40 mL of a mixed solution (containing 0.1 mol / L calcium chloride, 0.1 mol / L zinc chloride, 0.1 mol / L copper chloride, and 0.1 mol / L ferric chloride). The mixture was shaken on a shaker again for 10 h, then filtered and washed. After drying, multi-element-loaded manganese ore was obtained.

[0113] S3: Preparation of supported manganese ore slow-release fertilizer:

[0114] The obtained multi-element-loaded manganese ore was mixed with 375 mg of lignin to prepare the manganese ore slow-release fertilizer in this example.

[0115] The process flow diagram for preparing the supported manganese ore slow-release fertilizer in this example is as follows: Figure 5 As shown.

[0116] The loaded manganese ore slow-release fertilizer in this example was added to the flooded paddy soil, and then a culture experiment was conducted. On the 3rd, 6th and 9th days, the soil suspension was filtered through a 0.22 μm filter to evaluate the effect of the loaded manganese ore slow-release fertilizer on the content of manganese, potassium, iron, calcium, zinc and copper nutrients. The specific test results are shown in Table 8.

[0117] Table 8 shows the test results of the effect of this example on improving the levels of various nutrients in the soil.

[0118]

[0119] As shown in Table 8, this example uses a variety of nutrients to load natural manganese ore, which is then mixed with lignin. This results in the manganese ore loaded with multiple nutrients being applied to the soil, which can significantly increase the content of various nutrients (including manganese, potassium, iron, calcium, zinc, copper, etc.) in the soil. This further demonstrates that the natural manganese ore in this invention can serve as a carrier to load multiple nutrients, thereby acting as a slow-release fertilizer to enhance the content of nutrients in the soil and achieve a slow-release effect.

[0120] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A slow-release fertilizer, characterized in that: It includes modified manganese ore, nutrients, and lignin; the modified manganese ore is loaded with nutrients. The slow-release fertilizer is prepared using a method comprising the following steps: Manganese ore is prepared by reacting it sequentially with alkali metal borohydrides, metal salts, and lignin. The mixing reaction is carried out using an oscillator. The metal salt includes at least one of potassium salt, iron salt, calcium salt, copper salt, and zinc salt; The alkali metal borohydride is potassium borohydride.

2. The slow-release fertilizer according to claim 1, characterized in that: The nutrients include at least one of iron, manganese, zinc, copper, potassium, and calcium.

3. The slow-release fertilizer according to claim 1, characterized in that: The mass ratio of the manganese ore to the lignin is 5:(3~4).

4. The slow-release fertilizer according to claim 1, characterized in that: The modified manganese ore is manganese ore modified with alkali metal borohydrides.

5. The slow-release fertilizer according to claim 4, characterized in that: The mass ratio of the manganese ore to the alkali metal borohydride is 50:(0.5~1.5).

6. The slow-release fertilizer according to claim 4, characterized in that: The manganese ore has at least one of the following characteristics: (a) The specific surface area of ​​the manganese ore is 20-30 m². 2 / g; (b) The manganese ore has a porous structure; (c) The pore volume of the manganese ore is 0.06~0.07 cm³. 3 / g; (d) The average pore diameter of the manganese ore is 10~15 nm; (e) The manganese ore includes platy manganese ore.

7. The method for preparing the slow-release fertilizer according to any one of claims 1 to 6, characterized in that: Includes the following steps: The slow-release fertilizer is prepared by reacting manganese ore sequentially with alkali metal borohydrides, metal salts, and lignin.

8. The method for preparing slow-release fertilizer according to claim 7, characterized in that: The mixing reaction is carried out using an oscillator. And / or, the mixing reaction time is 1 to 24 hours.

9. The method for preparing slow-release fertilizer according to claim 7, characterized in that: The metal salt includes at least one of potassium salt, iron salt, calcium salt, copper salt, and zinc salt.

10. The application of the slow-release fertilizer according to any one of claims 1 to 6 in the field of fertilizers.

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