Preparation method of rare earth slow-release fertilizer for alfalfa

Abstract

The present application relates to a kind of preparation methods of rare earth slow-release fertilizer for alfalfa.The method is to add the mixture of concentrated sulfuric acid and concentrated nitric acid to active carbon and carry out hydrophilic treatment;The active carbon treated is respectively subjected to humic acid adsorption treatment and lanthanum sulfate+cerium sulfate soaking treatment;The active carbon adsorbed humic acid is mixed with the active carbon adsorbed rare earth sulfate uniformly, and rare earth slow-release fertilizer is obtained.The present application slowly releases humic acid and rare earth sulfate by active carbon, and slowly ionizes rare earth ion, realizes the purpose of slowly releasing soluble rare earth-humic acid complex, and guarantees the efficiency and long-acting of rare earth fertilizer.The present application is simple in operation, low in product cost, and can obtain efficient rare earth slow-release fertilizer for the quality improvement and yield increase of alfalfa, with significant industrialization advantage.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of agricultural fertilizers, and relates to a preparation method of a rare earth slow-release fertilizer for alfalfa. BACKGROUND

[0002] The production and use of chemical fertilizers are important guarantees for improving grain yield. In addition to nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer being the largest amount of fertilizers required by crops, rare earth elements are widely used in fertilizers due to their effects of regulating plant root growth, strengthening photosynthesis and nutrient absorption, and improving plant stress resistance. Alfalfa is an important forage crop and is cultivated in most areas in northern China. At present, the demand for high-quality beef and dairy products is large, and therefore, the production of high-quality forage is urgently required, and the planting of alfalfa is increasingly valued. At present, there are problems such as low yield and poor quality in alfalfa production, and how to improve the yield and quality of alfalfa and increase its economic value has become a problem to be solved. The application of fertilizers, including rare earth fertilizers, is one of important ways to promote high yield and high quality of alfalfa. In agricultural production, the most widely used rare earth is lanthanum and cerium and their mixture. Due to the inevitable presence of phosphate and carbonate in the soil, the application of rare earth fertilizer is easy to form insoluble rare earth phosphate and rare earth carbonate, which greatly reduces the fertilizer efficiency of rare earth or even makes it ineffective.

[0003] However, soluble rare earth fertilizers have a short time effect and are difficult to supply the required elements to crops for a long time. Therefore, improving the long-acting property of rare earth fertilizers is a problem to be solved.

[0004] The prior art mainly focuses on improving the efficiency of rare earth fertilizers. For example, graphene is used as a carrier of rare earth elements, and rare earth oxides are dispersed on the surface of graphene by ball milling to obtain graphene-rare earth composite fertilizer, which can greatly reduce the loss of rare earth elements. The method uses expensive graphene, and the overall cost is high. There is also a method of taking rare earth carbonate as raw material, adding chelating agent diethylene triamine pentaacetic acid (DTPA), sodium (potassium) hydroxide, heating at 85-95 DEG C, filtering impurities and drying to obtain white powder DTPA chelated rare earth fertilizer. The chelated rare earth fertilizer is completely dissolved in water and can be used with phosphorus fertilizer and the like. The above method relates to the preparation process of soluble rare earth fertilizer, and directly synthesizes rare earth chelate, which has problems such as easy loss of rare earth and short fertilizer efficiency period in the use process. However, how to solve the long-acting property of rare earth fertilizer has not been solved. Therefore, it is very important to develop a kind of rare earth slow-release fertilizer with low cost and environmental friendliness. SUMMARY

[0005] The purpose of the present application is to provide a preparation method of a rare earth slow-release fertilizer for alfalfa, which is safe and efficient, has low cost and simple preparation method.

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

[0007] A preparation method of a rare earth slow-release fertilizer for alfalfa, comprising at least the following steps:

[0008] Step one: hydrophilic modification treatment is performed on activated carbon to obtain hydrophilic modified activated carbon;

[0009] Step two: the hydrophilic modified activated carbon is immersed in a solution containing humic acid for treatment to obtain activated carbon adsorbed with humic acid;

[0010] Step three: the hydrophilic modified activated carbon is immersed in a solution containing lanthanum sulfate and cerium sulfate for treatment to obtain activated carbon adsorbed with rare earth sulfate;

[0011] Step four: the activated carbon adsorbed with humic acid and the activated carbon adsorbed with rare earth sulfate are mixed to obtain the rare earth slow-release fertilizer for alfalfa.

[0012] Optionally, in the step one, the specific surface area of the activated carbon is 100-1000 m 2 / g;

[0013] Optionally, the activated carbon is subjected to hydrophilic modification treatment by using a mixed solution of sulfuric acid and nitric acid.

[0014] Optionally, in the step one, 98% concentrated sulfuric acid and 68% concentrated nitric acid are mixed in a volume ratio of 10:1-5 to obtain the mixed solution of sulfuric acid and nitric acid, and the activated carbon is added to the mixed solution of sulfuric acid and nitric acid for soaking, the amount of the activated carbon added is 10-50 g / L, the soaking temperature is 25-65°C, and the soaking time is 30-120 min.

[0015] Optionally, in the step two, the hydrophilic modified activated carbon is added to a saturated humic acid solution for oscillation treatment for 10-100 min. In this step, the humic acid is fixed on the surface of the activated carbon in the form of adsorption, which is beneficial to slow release of the humic acid in the soil.

[0016] Optionally, in the step three, the solution containing lanthanum sulfate and cerium sulfate is a saturated solution, and the molar ratio of lanthanum sulfate to cerium sulfate is 1-x / x, x=0.1-0.9, and the immersion time is 30-120 min.

[0017] In this step, the rare earth sulfate is filled in the pores of the activated carbon, and the slow release of the rare earth sulfate in the soil is facilitated by virtue of the slightly soluble property of the rare earth sulfate.

[0018] Optionally, in the step four, the mass ratio of the activated carbon adsorbed with humic acid to the activated carbon adsorbed with rare earth sulfate is 50-5:1.

[0019] The application further discloses the rare earth slow-release fertilizer for alfalfa prepared by the above method.

[0020] The application further provides application of the rare earth slow-release fertilizer for alfalfa in alfalfa production.

[0021] The application provides a preparation method of the rare earth slow-release fertilizer for alfalfa, which utilizes the adsorption and rich pore characteristics of activated carbon to fix humic acid and rare earth on the surface and in the pores of the activated carbon respectively. The activated carbon slowly releases humic acid and the rare earth sulfate slowly ionizes rare earth ions, so that the slow release of the soluble rare earth-humic acid complex is realized, the efficiency and long-acting property of the rare earth fertilizer are ensured, and the short time limitation of the existing soluble rare earth fertilizer is effectively avoided. The efficient rare earth slow-release fertilizer is obtained through simple soaking, shaking, drying and mixing. The preparation method has simple operation, low product cost and considerable economic benefits, and meets the demand of large-scale commercial application. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the total content of soluble lanthanum and cerium in the alfalfa soil after the rare earth slow-release fertilizer is applied. DETAILED DESCRIPTION

[0023] The following examples are provided to better further understand the application, and do not limit the best embodiments, and do not constitute a limitation on the content and protection scope of the application. Any person under the inspiration of the application or the combination of the application with other prior art features obtains any product same or similar to the application, which falls within the protection scope of the application.

[0024] The specific experimental steps or conditions are not indicated in the examples, and can be performed according to the conventional experimental steps or conditions described in the literature in the field. The reagents or instruments used are not indicated by the manufacturer, and are conventional reagent products that can be obtained by market purchase.

[0025] Example 1

[0026] (1) 100 g of activated carbon with a specific surface area of 100 m 2 / g is weighed, 2.0 L of a 98% sulfuric acid and 68% nitric acid mixed solution with a volume ratio of 10:1 is added to the activated carbon, and the solid-liquid ratio is 30 g / L. 25℃ soaking for 30 min, washing, and 110℃ drying for standby;

[0027] (2) 2.0 L of deionized water is measured, humic acid is added to the deionized water while stirring until the humic acid cannot be dissolved, and a saturated humic acid solution is prepared; 500 mL of the saturated humic acid solution is added to 90.0 g of the activated carbon treated in step (1) of Example 1, shaken for 10 min, filtered, and dried at 110℃ for standby;

[0028] (3) Take 2.0 L of deionized water, and add lanthanum sulfate and cerium sulfate (molar ratio La / Ce = 5 / 5) to it while stirring until lanthanum sulfate and cerium sulfate cannot be dissolved, to prepare a saturated lanthanum sulfate and cerium sulfate solution; take 10.0 g of the activated carbon treated in step (1) of Example 1, and add 500 mL of the saturated lanthanum sulfate and cerium sulfate solution to it, soak for 30 min, filter, and dry at 110°C for standby;

[0029] (4) Mix 20.0 g of the activated carbon adsorbing humic acid in step (2) and step (3) of Example 1 and 4.0 g of the activated carbon adsorbing rare earth sulfate respectively, and mix evenly to obtain a rare earth slow-release fertilizer.

[0030] Example 2

[0031] (1) Take 100 g of activated carbon with a specific surface area of 100 m 2 / g, add 2.0 L of a 98% sulfuric acid and 68% nitric acid mixed solution with a volume ratio of 10:2 to it, and the solid-liquid ratio is 30 g / L. Soak at 45°C for 60 min, wash, and dry at 110°C for standby;

[0032] (2) Take 2.0 L of deionized water, and add humic acid to it while stirring until humic acid cannot be dissolved, to prepare a saturated humic acid solution; add 500 mL of the saturated humic acid solution to 90.0 g of the activated carbon treated in step (1) of Example 1, shake for 30 min, filter, and dry at 110°C for standby;

[0033] (3) Take 2.0 L of deionized water, and add lanthanum sulfate and cerium sulfate (molar ratio La / Ce = 5 / 5) to it while stirring until lanthanum sulfate and cerium sulfate cannot be dissolved, to prepare a saturated lanthanum sulfate and cerium sulfate solution; take 90.0 g of the activated carbon treated in step (1) of Example 1, and add 500 mL of the saturated lanthanum sulfate and cerium sulfate solution to it, soak for 60 min, filter, and dry at 110°C for standby;

[0034] (4) Mix 40.0 g of the activated carbon adsorbing humic acid in step (2) and step (3) of Example 2 and 4.0 g of the activated carbon adsorbing rare earth sulfate respectively, and mix evenly to obtain a rare earth slow-release fertilizer.

[0035] Example 3

[0036] (1) Take 100 g of activated carbon with a specific surface area of 100 m 2 / g, add 2.0 L of a 98% sulfuric acid and 68% nitric acid mixed solution with a volume ratio of 10:1 to it, and the solid-liquid ratio is 30 g / L. Soak at 55°C for 90 min, wash, and dry at 110°C for standby;

[0037] (2) Take 2.0 L of deionized water, add humic acid to it, stir while adding, until the humic acid cannot be dissolved, prepare a saturated humic acid solution; add 90.0 g of activated carbon treated in step (1) of Example 1 to 500 mL of saturated humic acid solution, shake for 70 min, filter, dry at 110°C for standby;

[0038] (3) Take 2.0 L of deionized water, add lanthanum sulfate and cerium sulfate (molar ratio La / Ce = 5 / 5) to it, stir while adding, until the lanthanum sulfate and cerium sulfate cannot be dissolved, prepare a saturated lanthanum sulfate and cerium sulfate solution; take 10.0 g of activated carbon treated in step (1) of Example 1, add 500 mL of saturated lanthanum sulfate and cerium sulfate solution to it, soak for 90 min, filter, dry at 110°C for standby;

[0039] (4) Mix 60.0 g and 4.0 g of activated carbon adsorbed with humic acid in step (2) and step (3) of Example 3 and activated carbon adsorbed with rare earth sulfate respectively, mix evenly, obtain rare earth slow-release fertilizer.

[0040] Example 4

[0041] (1) Take 100 g of activated carbon with a specific surface area of 100 m 2 / g, add 2.0 L of 98% sulfuric acid and 68% nitric acid mixed solution with a volume ratio of 10:2, solid-liquid ratio 30 g / L. Soak at 65°C for 120 min, wash, dry at 110°C for standby;

[0042] (2) Take 2.0 L of deionized water, add humic acid to it, stir while adding, until the humic acid cannot be dissolved, prepare a saturated humic acid solution; add 90.0 g of activated carbon treated in step (1) of Example 1 to 500 mL of saturated humic acid solution, shake for 100 min, filter, dry at 110°C for standby;

[0043] (3) Take 2.0 L of deionized water, add lanthanum sulfate and cerium sulfate (molar ratio La / Ce = 5 / 5) to it, stir while adding, until the lanthanum sulfate and cerium sulfate cannot be dissolved, prepare a saturated lanthanum sulfate and cerium sulfate solution; take 90.0 g of activated carbon treated in step (1) of Example 1, add 500 mL of saturated lanthanum sulfate and cerium sulfate solution to it, soak for 120 min, filter, dry at 110°C for standby;

[0044] (4) Mix 80.0 g and 4.0 g of activated carbon adsorbed with humic acid in step (2) and step (3) of Example 4 and activated carbon adsorbed with rare earth sulfate respectively, mix evenly, obtain rare earth slow-release fertilizer.

[0045] Comparative Example 1

[0046] (1) adding a mixture of 98% sulfuric acid and 68% nitric acid with a volume ratio of 10:2 to activated carbon with a specific surface area of 100 m 2 / g at a solid-liquid ratio of 30 g / L. Soaking at 45°C for 60 min, washing, and drying at 110°C for standby;

[0047] (2) measuring 2.0 L of deionized water, adding humic acid to it while stirring until the humic acid cannot be dissolved, preparing a saturated humic acid solution; adding 40.0 g of activated carbon treated in step (1) of Comparative Example 1 to 500 mL of the saturated humic acid solution, shaking for 30 min, filtering, and drying at 110°C to obtain a rare earth-free fertilizer.

[0048] Comparative Example 2

[0049] (1) adding a mixture of 98% sulfuric acid and 68% nitric acid with a volume ratio of 10:2 to activated carbon with a specific surface area of 100 m 2 / g at a solid-liquid ratio of 30 g / L. Soaking at 45°C for 60 min, washing, and drying at 110°C for standby;

[0050] (2) measuring 2.0 L of deionized water, adding lanthanum sulfate and cerium sulfate (molar ratio La / Ce = 5 / 5) to it while stirring until the lanthanum sulfate and cerium sulfate cannot be dissolved, preparing a saturated lanthanum sulfate and cerium sulfate solution; weighing 10.0 g of activated carbon treated in step (1) of Comparative Example 2, adding 500 mL of the saturated lanthanum sulfate and cerium sulfate solution to it, soaking for 60 min, filtering, and drying at 110°C to obtain a rare earth sulfate fertilizer. Mixing 40 g of the modified activated carbon in step 1 and 4.0 g of the activated carbon adsorbing rare earth sulfate together to obtain a rare earth fertilizer.

[0051] The final rare earth slow-release fertilizer obtained in each example and comparative example was respectively applied to a plot (10 m 2 ) of planting alfalfa (the amount of rare earth sulfate fertilizer was 1.5 kg / hm 2 ), and the total content of soluble lanthanum and cerium in the soil was measured as Figure 1 .

[0052] According to Figure 1The determination results show that the contents of soluble lanthanum and cerium in the soil after 1 month, 3 months and 6 months of applying the rare earth slow-release fertilizer (Examples 1-4) to alfalfa are higher than those in the soil without rare earth (Comparative Example 1) and the soil with application of the rare earth sulfate fertilizer (Comparative Example 2). This indicates that the prepared rare earth slow-release fertilizer effectively increases the contents of soluble lanthanum and cerium in the soil. The contents of soluble lanthanum and cerium in Examples 1-4 gradually increase slowly with the increase of the application time, which indicates that the rare earth fertilizer is slowly released into the soil with time, and the slow release of the rare earth elements in the soil is more in line with the demand law of the alfalfa plant for beneficial elements. The contents of soluble lanthanum and cerium in the soil with application of the rare earth sulfate fertilizer (Comparative Example 2) are slightly higher than those in the soil without rare earth (Comparative Example 1), but are still lower than those in the soil with application of the rare earth slow-release fertilizer (Examples 1-4), which indicates that the rare earth sulfate is difficult to be effectively absorbed by alfalfa without the complexation of humic acid. Therefore, the prepared rare earth slow-release fertilizer can be slowly released in the soil for a long time, thereby improving the effectiveness of the fertilizer and promoting the growth of the alfalfa plant, so as to achieve the purpose of yield increase.

[0053] The measured results of the growth indexes and yield of alfalfa are shown in Table 1.

[0054] Table 1

[0055] Group Plant height (cm) Leaf weight per plant (g) Yield (kg / hm 2 )]]> Example 1 76 2.23 7875 Example 2 88 3.02 9012 Example 3 85 2.86 8863 Example 4 74 2.07 7632 Comparative Example 1 70 1.83 7093 Comparative Example 2 72 2.04 7488

[0056] As shown in Table 1, the plant height of alfalfa with application of the rare earth slow-release fertilizer (Examples 1-4) is higher than that without rare earth and the rare earth sulfate fertilizer (Comparative Examples 1-2), and the plant height increases first (Examples 1-2) and then decreases (Examples 3-4) with the increase of the content of soluble rare earth in the soil after application of the rare earth slow-release fertilizer. The rare earth slow-release fertilizer has similar effects on the leaf weight per plant and the fresh grass yield of alfalfa as on the plant height. This may be because low-concentration rare earth elements promote the growth of alfalfa, while high-concentration rare earth elements inhibit the growth of alfalfa. Therefore, the prepared rare earth slow-release fertilizer can effectively promote the growth of alfalfa, so as to achieve the purpose of yield increase.

[0057] In summary, the preparation method of the rare earth fertilizer for alfalfa provided in the present application can obtain a high-efficiency rare earth slow-release fertilizer. The preparation method is simple in operation and low in product cost, and has significant industrialization advantages.

[0058] In addition, it should be noted that the above is only a preferred embodiment of the present application, and is not limited to the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a rare earth slow-release fertilizer for alfalfa, characterized in that, Includes at least the following steps: Step 1: Perform hydrophilic modification treatment on activated carbon to obtain hydrophilic modified activated carbon; Step 2: The hydrophilic modified activated carbon is impregnated in a saturated humic acid solution to obtain activated carbon adsorbed with humic acid. Step 3: The hydrophilic modified activated carbon is impregnated in a solution containing lanthanum sulfate and cerium sulfate to obtain activated carbon adsorbed with rare earth sulfates; the solution containing lanthanum sulfate and cerium sulfate is a saturated solution. Step 4: Mix the activated carbon adsorbed with humic acid and the activated carbon adsorbed with rare earth sulfate evenly to obtain the alfalfa rare earth slow-release fertilizer; the mass ratio of activated carbon adsorbed with humic acid to activated carbon adsorbed with rare earth sulfate is 50~5:

1.

2. The preparation method according to claim 1, characterized in that, In step one, the specific surface area of ​​the activated carbon is 100~1000 m². 2 / g.

3. The preparation method according to claim 1, characterized in that, In step one, the activated carbon is hydrophilically modified using a mixture of sulfuric acid and nitric acid.

4. The preparation method according to claim 3, characterized in that, In step one, the method of hydrophilic modification of activated carbon using a mixture of sulfuric acid and nitric acid is as follows: 98% concentrated sulfuric acid and 68% concentrated nitric acid are mixed at a volume ratio of 10:1 to 5 to obtain the sulfuric acid and nitric acid mixture. Activated carbon is added to the sulfuric acid and nitric acid mixture for soaking. The amount of activated carbon added is 10 to 50 g / L, the soaking temperature is 25 to 65 ℃, and the soaking time is 30 to 120 min.

5. The preparation method according to claim 1, characterized in that, In step two: the hydrophilic modified activated carbon is added to a saturated humic acid solution and shaken for 10-100 min.

6. The preparation method according to claim 1, characterized in that, In step three, the molar ratio of lanthanum sulfate to cerium sulfate in the solution containing lanthanum sulfate and cerium sulfate is 1- x : x, x =0.1~0.9; soaking time is 30~120 min.

7. A rare earth slow-release fertilizer for alfalfa prepared by any one of the methods in claims 1 to 6.

8. The application of the rare earth slow-release fertilizer for alfalfa according to claim 7 in alfalfa production.

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