Magnesium-based ultra-stable mineralized functional materials are used as slow-release magnesium fertilizers to promote crop growth by supplementing magnesium in the soil.

Abstract

This invention relates to the field of agricultural fertilizer and soil improvement technology, and discloses the application of a magnesium-based ultra-stable mineralized functional material as a slow-release magnesium fertilizer to promote crop growth through soil magnesium supplementation. This invention is the first to directly use a magnesium-based ultra-stable mineralized functional material (i.e., magnesium-based hydrotalcite) as a primary slow-release magnesium fertilizer, breaking through the traditional limitations of this material as only a carrier, adsorbent, and passivating agent, and expanding a new agricultural application direction for magnesium-based hydrotalcite functional materials.

Description

Technical Field

[0001] This invention relates to the field of agricultural fertilizer and soil improvement technology, specifically to a novel application of a magnesium-based ultra-stable mineralized functional material as a slow-release magnesium fertilizer to promote crop growth and increase yield by supplementing magnesium in the soil. Background Technology

[0002] Magnesium is a core component of chlorophyll and participates in key physiological processes such as photosynthesis, enzyme activation, carbohydrate transport, and protein synthesis. The available magnesium content in soils in some regions is generally low, mainly due to: (1) long-term application of nitrogen, phosphorus, and potassium fertilizers with neglect of micronutrient supplementation; (2) easy leaching of magnesium ions in acidic soils; and (3) high-yield crops consuming large amounts of magnesium. Magnesium deficiency leads to problems such as interveinal yellowing, decreased photosynthetic efficiency, poor root development, and reduced yield and quality in crops. Therefore, developing efficient, slow-release magnesium supplements has significant application value.

[0003] Currently, magnesium supplementation materials are mainly classified into the following categories: (1) Quick-dissolving magnesium fertilizer (represented by magnesium sulfate): Magnesium sulfate (MgSO4•7H2O) has high water solubility and dissolves rapidly after being applied to the soil, which can increase the magnesium concentration in the soil solution in a short period of time. However, it has obvious defects: ① Easy leaching: Under rainfall or irrigation conditions, magnesium ions are lost with water, and the utilization rate is usually less than 30%; ② Short effective period: A single application can only maintain the effect for 15-30 days; ③ Risk of overdose: The rapid release may lead to local salt damage or other problems with other cations (K). + Ca² + It produces an antagonistic effect.

[0004] (2) Slow-release / controlled-release magnesium fertilizer: There have been attempts to prepare slow-release fertilizers by combining magnesium salts with coating materials. CN106699455A discloses a biodegradable slow-release fertilizer containing magnesium sulfate and its preparation method, which combines magnesium sulfate with biochar, humic acid and coating materials to achieve slow release of nutrients. However, this type of technology still uses magnesium sulfate as the magnesium source, and the release rate of magnesium mainly depends on the degradation of the physical coating layer, which has problems such as increased cost of coating materials and the risk of sudden release after the coating layer breaks.

[0005] (3) Traditional insoluble magnesium-based materials: Magnesium oxide, magnesium hydroxide and lightly calcined magnesium powder and other traditional magnesium-based materials have low solubility and a certain degree of slow release, but their magnesium release rate is difficult to control and they lack soil improvement function. Magnesium ore powder (such as magnesite powder) exists in mineral form and has extremely low solubility, so its effect on supplementing magnesium for crops in the current season is limited.

[0006] Hydrotalcite is a type of anionic clay material with a layered structure. Hydrotalcite has a unique layered structure, adjustable layer metal composition, and good anion exchange capacity. Magnesium-based hydrotalcite (such as MgAl-LDH, MgFe-LDH, etc.) contains a large amount of magnesium in its layers, and magnesium ions exist stably in the layers in a structural form, which has potential slow-release properties. Existing applications of magnesium-based hydrotalcite in agriculture mainly focus on: (1) as a carrier for pesticides or fertilizers; (2) as an adsorbent or passivating agent for acidic heavy metal contaminated soils. There are no mature technical solutions or application reports on using it as a source of magnesium fertilizer to directly supplement magnesium in the soil and promote crop growth and yield. Summary of the Invention

[0007] In response to the technical shortcomings of existing conventional magnesium fertilizers, such as low utilization rate, short effective period, easy leaching, easy to cause soil salinization and damage to soil micro-ecology, this invention provides a magnesium-based ultra-stable mineralization functional material as a slow-release magnesium fertilizer to promote crop growth by supplementing magnesium in the soil.

[0008] Magnesium-based ultra-stable mineralization functional materials (i.e., magnesium-based hydrotalcite) are applied directly to farmland soil as slow-release magnesium fertilizer. Relying on the material's unique layered crystal structure, magnesium ions are released slowly, significantly reducing magnesium leaching loss. At the same time, it also has additional functions such as optimizing soil microbial communities and protecting soil enzyme activity, achieving a long-term and stable supply of magnesium. While supplementing magnesium, it improves the soil microecology, promotes crop growth, and increases yield and quality, thus expanding the application scope of magnesium-based hydrotalcite in modern agriculture.

[0009] To achieve the above objectives, this invention provides a magnesium-based ultra-stable mineralized functional material as a slow-release magnesium fertilizer to promote crop growth by supplementing magnesium in the soil.

[0010] The beneficial technical effects achieved by the present invention through the above technical solution are as follows: (1) This invention is the first to use magnesium-based ultra-stable mineralization functional material (i.e. magnesium-based hydrotalcite) directly as the main slow-release magnesium fertilizer, breaking through the traditional application limitations of this material as only a carrier, adsorbent, and passivator, and expanding the new agricultural application direction of magnesium-based hydrotalcite functional material.

[0011] (2) Magnesium-based ultra-stable mineralized functional materials have a special layered crystal structure. Magnesium ions are stably bound in the layered skeleton. In the soil system, magnesium ions are slowly dissolved and released in the layered skeleton. The nutrient release rate is much lower than that of fast-acting magnesium fertilizers such as magnesium sulfate, which can effectively reduce magnesium leaching and extend the nutrient supply cycle.

[0012] (3) Magnesium-based ultra-stable mineralizing functional materials do not contain harmful base ions such as sulfate, which can completely avoid the soil salinity problem caused by fast-acting magnesium fertilizers and make them safer to apply. The hydroxide ions that are slowly dissolved can moderately increase the pH value of acidic soils and achieve in-situ improvement of acidic soils. In addition, the layered structure of magnesium-based ultra-stable mineralizing functional materials can buffer soil ion stress, optimize the microbial living environment, effectively protect the activity of soil functional enzymes, and comprehensively improve the soil micro-ecological environment.

[0013] (4) Magnesium-based ultra-stable mineralized functional materials have the advantages of readily available raw materials, mature preparation process and controllable comprehensive cost, and are ready for large-scale application in agricultural production. Attached Figure Description

[0014] Figure 1 This is a schematic diagram illustrating the effect of different treatment groups on the rate of magnesium leaching in the soil in Test Example 1 of this invention; Figure 2 These are partial photographs of the garlic test process in Test Example 2 of this invention. Figure 3 This is a schematic diagram illustrating the effects of different treatment groups on the water-soluble magnesium content in soil in Test Example 2 of this invention; Figure 4 This is a schematic diagram illustrating the effects of different treatment groups on the activities of sucrase and cellulase in soil in Test Example 2 of this invention; Figure 5 This is a schematic diagram illustrating the effects of different treatment groups on the activities of β-glucosidase, catalase, and acid phosphatase in soil in Test Example 2 of this invention. Figure 6 This is a schematic diagram illustrating the effects of different treatment groups on the total number of soil microorganisms in Test Example 2 of this invention; Figure 7 These are images of the garlic growth process in Test Example 2 of this invention; where (a) is the control group and (b) is the magnesium aluminum hydrotalcite treatment group. Figure 8 This is a field photo of the garlic sprouts in the magnesium fertilizer area during test example 2 of this invention. Detailed Implementation

[0015] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0016] This invention provides an application of magnesium-based ultra-stable mineralized functional material as a slow-release magnesium fertilizer to promote crop growth by supplementing magnesium in the soil.

[0017] This invention directly applies magnesium-based ultra-stable mineralization functional materials to magnesium-deficient soils, conventional farmland soils, or facility agriculture soils as a slow-release magnesium fertilizer. This addresses the problems of severe magnesium ion leaching, low utilization rate, and short effective period associated with existing magnesium fertilizers (especially magnesium sulfate). It also avoids the negative effects of high ionic strength caused by fast-acting magnesium fertilizers, such as soil salinization, microbial inhibition, and decreased soil enzyme activity. This invention replenishes available magnesium in the soil, improves the soil environment, promotes crop growth, increases crop yield and agricultural product quality, and simultaneously improves the soil's physical and chemical properties and micro-ecological environment.

[0018] The magnesium-based ultrastable mineralized functional material described in this invention is a commercially available finished product or prepared using conventional processes in the field.

[0019] In some embodiments of the present invention, the magnesium-based ultra-stable mineralization functional material is the sole component of slow-release magnesium fertilizer.

[0020] In some embodiments of the present invention, the magnesium-based ultrastable mineralized functional material is selected from at least one of magnesium aluminum hydrotalcite and magnesium iron hydrotalcite.

[0021] In some embodiments of the present invention, in the magnesium-based ultrastable mineralized functional material, the molar ratio of divalent magnesium ions to trivalent metal ions in the layers is 1:1 to 4:1.

[0022] In some embodiments of the present invention, in the magnesium-based ultrastable mineralized functional material, the molar ratio of divalent magnesium ions to trivalent metal ions in the layers is 2:1-4:1.

[0023] In some embodiments of the present invention, in the magnesium-based ultrastable mineralized functional material, the molar ratio of divalent magnesium ions to trivalent metal ions in the layers is 3:1.

[0024] In some embodiments of the present invention, the particle size D90 of the magnesium-based ultrastable mineralized functional material is less than 100 μm, preferably less than 50 μm, and more preferably less than 10 μm.

[0025] In some embodiments of the present invention, the application is to soil with a pH of 5.5-8.0.

[0026] In some embodiments of the present invention, the application targets are magnesium-deficient soils with an effective magnesium content below a critical threshold, ordinary field farmland soils, and soils from continuous cropping facility agriculture.

[0027] In practical applications, a one-time basal fertilizer application method is adopted, with specific application parameters as follows: 1) Application rate: Based on the dry basis of magnesium-based ultra-stable mineralized functional materials, apply 80-150 kg per mu, preferably 100 kg; 2) Application method: Before sowing or before crop transplanting, spread evenly on the soil surface and mix thoroughly with the soil during tilling. 3) Application depth: 10-30cm in the tillage layer; 4) Application period: Before crop sowing and before seedling transplanting; 5) Applicable soils: Magnesium-deficient soils with available magnesium content below the critical threshold, ordinary field farmland soils, and soils suitable for continuous cropping in facility agriculture. 6) Applicable crops: Leafy vegetables such as garlic, spinach, and amaranth, as well as grain crops such as rice. It can also be extended to various magnesium-loving cash crops.

[0028] The present invention will be described in detail below through embodiments.

[0029] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0030] The magnesium-based hydrotalcite used in the following examples and comparative examples is all commercially available industrial grade.

[0031] The types of materials and related parameters used in Examples 1-6 are shown in Table 1.

[0032] Table 1

[0033] The types of materials used in Comparative Examples 1-3 are shown in Table 2.

[0034] Table 2

[0035] Test Example 1: Comparative Test of Magnesium Release Characteristics The soil column leaching method was used to compare the release patterns and leaching losses of magnesium ions in soil with those of magnesium aluminum hydrotalcite functional materials and traditional magnesium sulfate heptahydrate and organic amendments (earthworm castings), thus verifying the slow-release and controlled leaching effects of the present invention.

[0036] (1) Test materials The tested soil was a typical acidic yellow soil from southern China, with a soil pH of 7.09, EC of 78.90 μs / cm, and water-soluble magnesium of 0.19 mg / kg, which is considered a severely magnesium-deficient soil.

[0037] (2) Test methods The soil column leaching method was employed. Equal masses of various magnesium-based hydrotalcite functional materials and magnesium sulfate heptahydrate were precisely weighed and thoroughly mixed with quantitatively air-dried test soil. The mixed samples were then packed into a standard leaching column (8 cm inner diameter, 30 cm height), with a quantitative filter paper and quartz sand placed at the bottom to prevent soil particles from being lost with the leaching solution. A quantitative amount of deionized water was added each time for leaching, simulating natural rainfall / irrigation conditions, for a total of three leaching cycles. The magnesium ion concentration in the leaching solution was determined using atomic absorption spectrophotometry, and the data were recorded throughout the process. Experiments without any added materials served as a blank control.

[0038] (3) Test results This experiment systematically evaluated the magnesium ion release characteristics of different magnesium source materials through three consecutive leaching cycles, using magnesium ion leaching concentration as the core indicator to verify the slow-release magnesium supply effect of each treatment group. The results are as follows: Figure 1 As shown.

[0039] Blank control group: The magnesium ion concentration remained at an extremely low level throughout the three leaching processes, proving that the soil itself had a severe deficiency of magnesium without external magnesium supplementation, and crops faced a potential risk of magnesium deficiency.

[0040] Comparative Example 1: Magnesium sulfate heptahydrate group exhibited a typical "burst release-cliff-like decay" characteristic, with a leaching rate as high as 99.5%. This result indicates that traditional magnesium sulfate is a fast-acting magnesium source, and almost all magnesium ions are lost in the first leaching, resulting in extremely low fertilizer utilization and environmental risks of causing secondary soil salinization and groundwater pollution.

[0041] Comparative Example 2: The concentration of magnesium ions leached in the first leaching was about 135 mg / L, which was significantly higher than that of the blank control. However, the concentration decreased rapidly to about 65 mg / L and 40 mg / L in the second and third leachings, respectively. The overall release was low and the duration was short, which could only provide magnesium for a short period of time and could not meet the long-term magnesium requirements of crops throughout their entire growth period.

[0042] Comparative Example 3: Magnesium-aluminum hydrotalcite + earthworm castings group: The magnesium ion concentration after the first leaching increased to approximately 160 mg / L, significantly higher than that of the magnesium-aluminum hydrotalcite group in Example 1. This indicates that the addition of earthworm castings did not enhance the slow-release effect. On the contrary, the organic matter components may have disrupted the layered crystal structure of the hydrotalcite, weakening the cage-locking effect of the layers on magnesium ions, leading to an abnormally high release of magnesium ions in the early stage, and the slow-release performance was significantly inferior to that of pure hydrotalcite material.

[0043] Treatment groups 1 and 2 showed a significantly reduced leaching magnesium concentration, effectively fixing a large amount of exogenous magnesium in the soil solid phase. Furthermore, there was no sudden nutrient release during continuous leaching, and the magnesium ion leaching concentration decreased steadily and gradually, effectively avoiding the drawbacks of magnesium sulfate's initial nutrient loss and subsequent magnesium deficiency. These treatments demonstrated significantly better magnesium ion retention capacity and slow-release stability than other treatment groups.

[0044] Example 3 treatment group: Compared with the single magnesium sulfate treatment group, the magnesium aluminum hydrotalcite formed by the low magnesium aluminum molar ratio still has a good stable slow-release ability. However, compared with Examples 1 and 2, due to the low magnesium aluminum molar ratio, the charge density of the layer is insufficient, the number of sites for holding magnesium ions is reduced, and the slow-release ability is significantly reduced.

[0045] Example 4 treatment group: Compared with Examples 1 and 2, the excessively high magnesium-aluminum molar ratio weakened the lattice binding ability, and the magnesium fixation and slow-release performance were significantly worse than the 3:1 ratio sample. However, compared with the single magnesium sulfate treatment group, the magnesium-aluminum hydrotalcite prepared with a high magnesium-aluminum ratio can still significantly inhibit the sudden release and leaching of magnesium ions.

[0046] Example 5 treatment group: Compared with Comparative Example 1, the 2:1 ratio of magnesium to iron hydrotalcite showed outstanding retention and slow-release effect; however, compared with Example 2 with the same system of 3:1 ratio, the reduction of the magnesium to iron molar ratio caused the stability of the layer structure to decrease, and the slow-release stability and magnesium retention capacity to deteriorate significantly.

[0047] Example 6 treatment group: The initial leaching magnesium ion dissolution was higher, the first round of nutrient release was greater, and the overall slow-release uniformity was not as good as in Example 1. However, compared with the rapid complete dissolution and large-scale leaching of magnesium sulfate in Comparative Example 1, the large-particle-size magnesium aluminum hydrotalcite can still significantly reduce magnesium leaching loss. However, compared with the fine-particle-size Example 1 with the same formula, the larger particle size significantly reduces the specific surface area of ​​the material, and ultimately the magnesium ion retention effect and slow-release stability are significantly reduced.

[0048] Test Example 2: Field Trial Verification (Garlic Growth Experiment) Under actual field production conditions, the effects of magnesium aluminum hydrotalcite from Example 1 as a slow-release magnesium fertilizer on the growth traits, soil physicochemical indicators, soil microecology, and crop yield of garlic cultivated in magnesium-deficient soil were verified, and a parallel comparison was made with conventional magnesium sulfate from Comparative Example 1.

[0049] (1) Basic information of the experiment Test site: Zhijiang Agricultural Security Facility Vegetable Co-prosperity Industrial Park, Kecheng District, Quzhou City, Zhejiang Province Trial period: November 2025 to March 2026 Test crop: Garlic (the main local variety) The test soil was a salinization-prone soil from continuous cropping in protected facilities, with a pH of 5.67, EC of 162.9 ms / cm, and water-soluble magnesium content of 108.17 mg / kg. It was classified as a slightly potentially magnesium-deficient soil, and high-yield crops are prone to magnesium deficiency in the later stages of growth, requiring preventative magnesium supplementation.

[0050] (2) Experimental design like Figure 2 As shown, the experiment consisted of three treatments: CK (blank control), T1 (conventional magnesium sulfate heptahydrate fertilizer, Comparative Example 1), and T2 (magnesium aluminum hydrotalcite functional material, Example 1). Each treatment was replicated three times, with each treatment occupying an area of ​​1.0 m², resulting in two whole-block experiments with a total area of ​​18.0 m². 2 In the field, a randomized block design was used; the T2 treatment group was administered 0.15 kg / m³. 2 Magnesium sulfate fertilizer should be applied at an equivalent amount of MgO to ensure consistent magnesium input. All fertilizers should be used as base fertilizer, spread before sowing and then tilled into the soil, mixing thoroughly with the top 10-30cm of soil. Garlic will be sown at the end of November 2025 and harvested in early March 2026. Irrigation, weeding, and pest and disease control throughout the entire growth period will be carried out in accordance with the local conventional management model for greenhouse garlic.

[0051] (3) Measurement indicators and methods Table 3. Description of Measurement Indicators

[0052] (4) Analysis of experimental results 1) Changes in the content of water-soluble magnesium ions in soil like Figure 3 As shown, compared with the control group, both magnesium sulfate and magnesium aluminum hydrotalcite treatments significantly (P<0.001) increased the water-soluble magnesium content in the soil. The water-soluble magnesium content in the magnesium sulfate treatment group reached 186.2 mg / kg, an increase of 173.8% compared with the control group; the water-soluble magnesium content in the magnesium aluminum hydrotalcite treatment group was 148.7 mg / kg, an increase of 118.7% compared with the control group. At the same time, the water-soluble magnesium content in the magnesium sulfate treatment group was significantly higher (P<0.001) than that in the magnesium aluminum hydrotalcite treatment group, indicating that there is a significant difference in the activation and release capacity of magnesium in the soil between the two magnesium fertilizers.

[0053] Magnesium sulfate, as a fast-acting inorganic magnesium fertilizer, can rapidly dissociate into Mg²⁺ in the soil. + and SO4² - This directly replenishes water-soluble magnesium in the soil solution. Therefore, it can significantly increase the water-soluble magnesium content in a short time, which is completely consistent with the nutrient release characteristics of fast-acting magnesium fertilizers. Magnesium-aluminum hydrotalcite is a layered bimetallic hydroxide slow-release magnesium source; its magnesium element exists in the form of a layered structure, requiring ion exchange, interlayer displacement, or slow dissolution to release Mg²⁺. +Therefore, the increase in water-soluble magnesium is lower than that of magnesium sulfate, which is consistent with the nutrient control characteristics of slow-release materials.

[0054] 2) Changes in soil functional enzyme activity Sucrase, cellulase, β-glucosidase, catalase, and acid phosphatase in soil are core functional enzymes for soil carbon cycling, redox cycling, and phosphorus cycling. Experimental results are as follows: Figure 4 and Figure 5 As shown.

[0055] Sucrase and cellulase: Both magnesium fertilizers inhibited enzyme activity, but magnesium sulfate had a stronger inhibitory effect. The sucrase activity in the control group was 594.8 μg glucose / g / min, with a 65.0% decrease in the magnesium sulfate treatment group and a 40.2% decrease in the magnesium-aluminum hydrotalcite treatment group. The cellulase activity in the control group was 1.31 μg glucose / g / min, with a 64.9% decrease in the magnesium sulfate treatment group and a 58.0% decrease in the magnesium-aluminum hydrotalcite treatment group. The differences between the groups were highly significant (P<0.001).

[0056] Overall, the inhibitory effects of the two magnesium fertilizers on the activity of enzymes related to soil carbon cycling showed a consistent pattern: magnesium sulfate > magnesium aluminum hydrotalcite.

[0057] Regarding β-glucosidase: the inhibitory effects of magnesium fertilizer were similar in both groups, with no significant difference between the groups; Regarding catalase: the catalase activity in the control group was 3.09 μmol H2O2 / g / min, while the magnesium sulfate treatment group showed a decrease of 52.1%, and the magnesium aluminum hydrotalcite treatment group showed a decrease of only 13.3%, demonstrating a significant protective effect against soil antioxidant enzymes.

[0058] Acid phosphatase: Magnesium sulfate has no significant effect on it, while magnesium aluminum hydrotalcite has a certain inhibitory effect.

[0059] Catalase participates in soil redox balance and removes H2O2 produced by microbial metabolism. Its activity directly reflects the soil's antioxidant capacity and the level of microbial health. Magnesium sulfate, as a strong electrolyte, causes far greater ion stress to microorganisms due to its rapid dissociation than slow-release magnesium aluminum double hydroxide (MLD), thus exhibiting a more significant inhibitory effect on catalase. The slow-release properties of MLD reduce ion shock, providing stronger protection for microorganisms and resulting in higher enzyme activity retention. At the phosphorus cycle level, the strong inhibition of acid phosphatase by MLD slows down the mineralization and release of organophosphates, reducing the risk of phosphorus leaching.

[0060] 3) Changes in the total number of soil microbial communities like Figure 6As shown, magnesium sulfate treatment significantly inhibited all three types of microorganisms, with a substantial decrease in the number of bacteria, fungi, and actinomycetes, by 37.8%, 38.0%, and 62.0%, respectively. Magnesium aluminum hydrotalcite treatment significantly increased the number of bacteria and actinomycetes, with increases of 57.1% and 11.5%, respectively, while the number of fungi remained roughly the same as the control group. These results are consistent with the soil enzyme activity data presented earlier: the strong inhibitory effect of magnesium sulfate on microorganisms directly led to a significant inhibition of the synthesis and secretion of microbial enzymes such as sucrase, cellulase, β-glucosidase, and catalase, resulting in a substantial decrease in enzyme activity. The growth-promoting effect of magnesium aluminum hydrotalcite on microorganisms explains its weak inhibitory characteristics on the activity of key enzymes such as catalase: the increase in the total number of microorganisms offset some of the negative effects of ion stress, ultimately resulting in a much higher enzyme activity retention rate than the magnesium sulfate treatment group. Magnesium aluminum hydrotalcite can optimize the soil microbial community structure and build a healthy soil microecology, which is the core reason for its enzyme activity protection and crop growth promotion.

[0061] 4) Changes in garlic plant height Table 4. Statistical results of plant height in each treatment group

[0062] Compared with the control group, the garlic plant height in the magnesium sulfate treatment group was significantly increased, reaching 38.84 cm in block 1 and 40.73 cm in block 2, with an average growth rate of 9-13% (approximately 11%). The magnesium aluminum hydrotalcite treatment group showed an even more significant improvement, with plant height increasing to 42.31 cm and 42.60 cm respectively, with an average growth rate of 18-19% (approximately 18%), which was significantly higher than that in the magnesium sulfate treatment group.

[0063] Overall, both magnesium fertilizers can promote the growth of garlic plants, with magnesium aluminum hydrotalcite showing a better growth-promoting effect than magnesium sulfate.

[0064] 5) Changes in garlic yield (fresh weight) Different magnesium fertilizer treatments all significantly promoted the accumulation of garlic sprout biomass, with significant differences in yield increase. The fresh weight yield of garlic sprouts in the control group was 0.27 kg / m²; the yield in the magnesium sulfate treatment group increased to 0.32 kg / m², an increase of 0.05 kg / m² compared to the control group, with a yield increase rate of 18.4%; the magnesium aluminum hydrotalcite (Mg-Al LDH) treatment showed a more prominent yield increase, with a fresh weight yield of garlic sprouts reaching 0.41 kg / m², an increase of 0.14 kg / m² compared to the control, with a yield increase rate as high as 52.2%.

[0065] Table 5 Results of fresh weight of garlic sprouts

[0066] The results showed that both magnesium fertilizers could effectively enhance the accumulation of fresh substances in garlic sprouts, and magnesium aluminum hydrotalcite had a significantly better effect on increasing yield and efficiency in the garlic sprout stage than traditional magnesium sulfate fertilizer. Compared with the control group, both magnesium sulfate and magnesium aluminum hydrotalcite significantly increased the fresh weight of garlic sprouts, confirming the promoting effect of magnesium supply on the vegetative growth of garlic.

[0067] Magnesium sulfate, as a fast-acting magnesium fertilizer, can quickly replenish available magnesium in the soil, improve magnesium nutrition in plants in the short term, and achieve a certain yield increase. However, under the influence of high salt ion stress, it has an inhibitory effect on soil microbial communities and various nutrient cycling enzymes, thus limiting its yield potential. Magnesium-aluminum hydrotalcite, on the other hand, can slowly and continuously release magnesium ions, stably maintaining soil magnesium supply. Simultaneously, it optimizes the soil microbial community structure, alleviates enzyme activity inhibition, improves the soil microecological environment and nutrient conversion capacity, and synergistically promotes garlic seedling growth and nutrient accumulation, ultimately exhibiting a highly significant yield increase advantage. These results further demonstrate that magnesium-aluminum hydrotalcite, as a slow-release magnesium fertilizer, when applied to garlic cultivation in magnesium-deficient continuously cropped facility soils, has excellent slow-release effects, high magnesium utilization rate, optimizes soil physicochemical properties and microbial communities, protects soil functional enzymes, significantly promotes crop growth, and increases yield. Its comprehensive application effect is superior to traditional magnesium sulfate.

[0068] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. Application of magnesium-based ultra-stable mineralized functional materials as slow-release magnesium fertilizer to promote crop growth by supplementing magnesium in the soil.

2. The application according to claim 1, wherein, The magnesium-based ultra-stable mineralization functional material is the sole component of the slow-release magnesium fertilizer.

3. The application according to claim 1 or 2, wherein, The magnesium-based ultrastable mineralized functional material is selected from at least one of magnesium aluminum hydrotalcite and magnesium iron hydrotalcite.

4. The application according to any one of claims 1-3, wherein, In the magnesium-based ultrastable mineralized functional material, the molar ratio of divalent magnesium ions to trivalent metal ions in the layers is 1:1 to 4:

1.

5. The application according to any one of claims 1-4, wherein, In the magnesium-based ultrastable mineralized functional material, the molar ratio of divalent magnesium ions to trivalent metal ions in the layers is 2:1-4:

1.

6. The application according to any one of claims 1-5, wherein, In the magnesium-based ultrastable mineralized functional material, the molar ratio of divalent magnesium ions to trivalent metal ions in the layers is 3:

1.

7. The application according to any one of claims 1-6, wherein, The particle size D90 of the magnesium-based ultrastable mineralized functional material is less than 100 μm, preferably less than 50 μm, and more preferably less than 10 μm.

8. The application according to any one of claims 1-7, wherein, The application is for soils with a pH of 5.5-8.

0.

9. The application according to any one of claims 1-8, wherein, The application targets magnesium-deficient soils with effective magnesium content below the critical threshold, ordinary field farmland soils, and soils from continuous cropping facility agriculture.

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