Acid red loam soil conditioner based on secondary product magnesium hydroxide and preparation method of acid red loam soil conditioner

Abstract

The invention provides an acid red loam soil conditioner based on secondary magnesium hydroxide and a preparation method thereof, and relates to the technical field of soil improvement. The acid red loam soil conditioner based on the secondary product magnesium hydroxide is prepared from the following raw materials in parts by mass: 27 to 33 parts of the secondary product magnesium hydroxide, 8 to 12 parts of a water-absorbing and fertilizer-preserving material, 27 to 33 parts of a porous material, 4 to 6 parts of slow-release coated trace elements and 22 to 28 parts of an organic fertilizer. Secondary products in the magnesium hydroxide production process are adopted as raw materials, the production cost is reduced, effective resource utilization of waste is achieved, compared with traditional lime, magnesium hydroxide is milder, the pH value of soil can be stably increased, the problem of excessive alkalization is avoided, meanwhile, magnesium is provided for plants, and healthy growth is promoted; in addition, the synergistic effect of magnesium hydroxide and the organic fertilizer does not destroy the stability of organic matters, can promote the activity of soil microorganisms, and further improves the soil structure and fertility.

Description

Technical Field

[0001] The present invention relates to the technical field of soil improvement, and particularly relates to an acidic red soil conditioner based on secondary magnesium hydroxide and a preparation method thereof. Background Art

[0002] Red soil has the characteristics of strong acidity, low organic matter content, poor soil structure, and poor air permeability. These problems seriously limit the growth of crops, resulting in a decline in crop yield and quality. Existing soil improvement methods usually focus on single functions, such as simple lime neutralization or organic fertilizer addition, and cannot comprehensively meet the improvement needs of red soil. In addition, the production cost of traditional conditioners is relatively high, and the environmental friendliness is not strong, making it difficult to achieve sustainable development.

[0003] In soil improvement, traditional lime (Ca(OH)2) has strong alkalinity and can quickly increase the pH value of the soil. However, it is also prone to excessive alkalization, resulting in soil structure and nutrient imbalance, and lacks the ability to provide trace elements required by plants. Further, due to its strong alkalinity, traditional lime will also cause the organic matter to decompose too quickly, releasing bad gases and reducing the effectiveness of organic fertilizers. Therefore, it cannot be mixed with organic fertilizers to make compound fertilizers, and cannot solve the problems of strong acidity and low organic matter content in red soil at the same time.

[0004] How to disclose a soil conditioner that can effectively neutralize the acidity of acidic red soil, increase the soil pH value, improve the physical structure of the soil, enhance the water and fertilizer retention capacity of the soil, and continuously provide necessary trace elements and nutrients for plants is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide an acidic red soil conditioner based on secondary magnesium hydroxide and a preparation method thereof to solve the problem that traditional soil conditioners cannot improve the soil pH value and organic matter content at the same time.

[0006] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides an acidic red soil conditioner based on secondary magnesium hydroxide, comprising the following raw materials in parts by mass:

[0008] 27 - 33 parts of secondary magnesium hydroxide, 8 - 12 parts of water-absorbing and fertilizer-retaining material, 27 - 33 parts of porous material, 4 - 6 parts of slow-release coated trace elements, and 22 - 28 parts of organic fertilizer.

[0009] Preferably, the content of magnesium hydroxide in the secondary magnesium hydroxide is 76 - 84%, and the content of silicate is 16 - 24%.

[0010] Preferably, the water-absorbing and fertilizer-retaining material includes one or more of superabsorbent resin, carboxymethyl cellulose, and starch-based water-absorbing material.

[0011] Preferably, the porous material includes one or more of diatomite, vermiculite, and perlite.

[0012] Preferably, the preparation method of the slow-release coated trace elements is as follows:

[0013] Mix the coating material, organic solvent, and inorganic salt and then dry to obtain the slow-release coated trace elements;

[0014] The coating material is polylactic acid and / or polyvinyl alcohol;

[0015] The inorganic salt includes 0.8 - 1.2 parts of boric acid, 1.2 - 1.8 parts of zinc sulfate, 1.7 - 2.3 parts of ferrous sulfate, and 0.35 - 0.65 parts of manganese sulfate by mass;

[0016] The organic solvent is ethanol or propanol solution, and the concentration of the organic solvent is 80 - 95wt%. The solvent can volatilize rapidly during the drying process and will not remain in the soil, having no adverse effect on plant growth.

[0017] The mass ratio of the coating material to the inorganic salt is 2 - 5:100, preferably 3 - 4:100.

[0018] The drying method is preferably spray drying, which can uniformly coat the coating material on the surface of the inorganic salt to ensure the stability and persistence of the slow-release effect.

[0019] Preferably, the organic fertilizer includes one or more of bio-organic fertilizer, humic acid organic fertilizer, earthworm compost, and commercial organic fertilizer.

[0020] The present invention also provides a preparation method of the above acidic red soil soil conditioner based on secondary magnesium hydroxide, including the following steps:

[0021] 1) Mix the secondary magnesium hydroxide with the water-absorbing and fertilizer-retaining material to obtain a mixed material;

[0022] 2) Mix the mixed material with the porous material, slow-release coated trace elements, and organic fertilizer to obtain the acidic red soil soil conditioner based on secondary magnesium hydroxide.

[0023] Preferably, the reaction time in step 1) is 1.5 - 2.5 h, and the mixing temperature is 20 - 30 °C.

[0024] The present invention has at least the following beneficial effects:

[0025] The present invention uses the secondary product in the production process of magnesium hydroxide as the raw material, which reduces the production cost, realizes the effective resource utilization of waste, and meets the requirements of environmental protection and sustainable development. Compared with traditional lime, magnesium hydroxide has mild alkalinity, can steadily increase the soil pH value, avoid the problem of excessive alkalization, and at the same time provide magnesium element for plants to promote healthy growth. In addition, the synergistic effect of magnesium hydroxide and organic fertilizer not only does not damage the stability of organic matter, but also promotes soil microbial activities, further improving the soil structure and fertility. The present invention develops a multifunctional soil conditioner by reasonably combining the secondary magnesium hydroxide with water-absorbing and fertilizer-retaining materials, porous materials, slow-release trace elements and organic fertilizer. It integrates pH value adjustment, water and fertilizer retention, soil structure improvement and continuous supply of trace elements, and can comprehensively improve the physical, chemical and biological properties of the soil, and is particularly suitable for the improvement of acidic red soil. Detailed implementation mode

[0026] The present invention provides an acidic red soil conditioner based on secondary magnesium hydroxide, comprising the following raw materials in parts by mass:

[0027] 27-33 parts of secondary magnesium hydroxide, 8-12 parts of water-absorbing and fertilizer-retaining materials, 27-33 parts of porous materials, 4-6 parts of slow-release coated trace elements, 22-28 parts of organic fertilizer; preferably 28-32 parts of secondary magnesium hydroxide, 9-11 parts of water-absorbing and fertilizer-retaining materials, 28-32 parts of porous materials, 4.5-5.5 parts of slow-release coated trace elements, 23-27 parts of organic fertilizer; more preferably 29-31 parts of secondary magnesium hydroxide, 10-11 parts of water-absorbing and fertilizer-retaining materials, 29-31 parts of porous materials, 5-5.5 parts of slow-release coated trace elements, 24-26 parts of organic fertilizer.

[0028] In the present invention, the content of magnesium hydroxide in the secondary magnesium hydroxide is 76-84%, preferably 78-82%, more preferably 79-80%; the content of silicate is 16-24%, preferably 18-22%, more preferably 20-21%.

[0029] The present invention uses secondary magnesium hydroxide as the raw material to prepare the soil conditioner, which can avoid the short-term drastic change of the soil pH value compared with pure magnesium hydroxide. The silicate has good physical properties, can improve the soil structure, increase the air permeability and water retention of the soil, thus providing a more favorable environment for the healthy growth of plant roots. In addition, silicate itself is also one of the important trace elements required for plant growth, which can enhance the stress resistance of plants and improve the disease resistance, insect resistance and drought resistance of crops. Therefore, the silicate in the secondary magnesium hydroxide not only improves the multifunctionality of the soil conditioner, but also further optimizes the comprehensive improvement effect of the soil.

[0030] In the present invention, the water-absorbing and fertilizer-retaining material includes one or more of a high molecular water-absorbing resin, carboxymethyl cellulose, and a starch-based water-absorbing material.

[0031] In the present invention, the porous material includes one or more of diatomite, vermiculite, and perlite.

[0032] In the present invention, the preparation method of the slow-release coated trace elements is as follows:

[0033] Mix the coating material, organic solvent, and inorganic salt, and then dry to obtain the slow-release coated trace elements;

[0034] The drying method is preferably spray drying.

[0035] In the present invention, the coating material is polylactic acid and / or polyvinyl alcohol.

[0036] In the present invention, the inorganic salt includes, by mass, 0.8 - 1.2 parts of boric acid, 1.2 - 1.8 parts of zinc sulfate, 1.7 - 2.3 parts of ferrous sulfate, and 0.35 - 0.65 parts of manganese sulfate; preferably 0.9 - 1.1 parts of boric acid, 1.3 - 1.7 parts of zinc sulfate, 1.8 - 2.2 parts of ferrous sulfate, and 0.4 - 0.6 parts of manganese sulfate; more preferably 1 - 1.05 parts of boric acid, 1.4 - 1.6 parts of zinc sulfate, 1.9 - 2.1 parts of ferrous sulfate, and 0.45 - 0.55 parts of manganese sulfate; 0.8 - 1.2 parts of boric acid, 1.2 - 1.8 parts of zinc sulfate, 1.7 - 2.3 parts of ferrous sulfate, and 0.4 - 0.5 parts of manganese sulfate.

[0037] The coating material has the property of slow degradation. When the particles enter the soil, with the action of moisture and microorganisms in the soil, the coating layer gradually degrades, and the trace elements are slowly released. This can avoid the phenomenon of nutrient waste or soil pollution caused by the one-time rapid release of trace elements, ensure the long-term continuous supply of trace elements in the soil, and meet the needs of plant growth.

[0038] In the present invention, the organic fertilizer includes one or more of bio-organic fertilizer, humic acid organic fertilizer, earthworm compost, and commercial organic fertilizer.

[0039] The present invention also provides a preparation method of the above acidic red soil soil conditioner based on secondary magnesium hydroxide, including the following steps:

[0040] 1) Mix the secondary magnesium hydroxide with the water-absorbing and fertilizer-retaining material to obtain a mixed material;

[0041] 2) Mix the mixed material with the porous material, slow-release coated trace elements, and organic fertilizer to obtain an acidic red soil soil conditioner based on secondary magnesium hydroxide.

[0042] In the present invention, first mixing the secondary magnesium hydroxide with the water-absorbing and fertilizer-retaining material can enable the water-absorbing and fertilizer-retaining material to coat the surface of magnesium hydroxide, so that magnesium hydroxide is gradually released during use, slowly increasing the pH value of the soil and avoiding drastic changes in the soil pH value, thereby protecting the microorganisms and nutrients in the soil and avoiding the death of microorganisms or nutrient loss caused by sudden pH changes.

[0043] In the present invention, the reaction time in step 1) is 1.5 to 2.5 h, preferably 1.75 to 2.25 h, and further preferably 2 h; the mixing temperature is 20 to 30 °C.

[0044] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0045] Example 1

[0046] Mix 30 parts of secondary magnesium hydroxide (magnesium hydroxide content is 80%, silicate and calcium compound content is 20%) with 10 parts of water-absorbing and fertilizer-retaining material (superabsorbent resin produced by Shandong Bluestar Dongda Chemical Group Co., Ltd., label SPA-101, polyacrylamide), and stir at a speed of 450 rpm for 2 h to obtain a mixed material. Then add 30 parts of porous material (diatomaceous earth produced by Inner Mongolia Yidong Resources Group Co., Ltd., label DD-100) and continue to stir for 25 min, and then add 5 parts of slow-release coated trace elements (dissolve 1.0 part of boric acid, 1.5 parts of zinc sulfate, 2.0 parts of ferrous sulfate, and 0.5 part of manganese sulfate in the ethanol solution of polyvinyl alcohol PVA and stir evenly. The dosage of polyvinyl alcohol is 3% of the total mass of inorganic salts, and then the coating material is evenly attached to the surface of the trace element particles by spray drying to obtain slow-release coated trace elements) and stir for 20 min. Finally, add 24 parts of organic fertilizer (biological organic fertilizer produced by Stanley Fertilizer Co., Ltd., label OF-301) and stir for 15 min to obtain an acidic red soil soil conditioner based on secondary magnesium hydroxide.

[0047] Example 2

[0048] 30 parts of inferior magnesium hydroxide (magnesium hydroxide content of 80%, silicate and calcium compound content of 20%) and 10 parts of water-absorbing and fertilizer-retaining materials (super absorbent resin produced by Shandong Bluestar Dongda Chemical Group, label SPA-101, polyacrylamide) were mixed and stirred at a speed of 450 rpm for 2 hours to obtain a mixed material, and then 30 parts of porous material (diatomaceous earth produced by Inner Mongolia Yidong Resources Group Co., Ltd., label DD-100) were added and stirred for 25 minutes, and then 5 parts of slow-release coated trace elements (boric acid 1. 0 parts, 1.5 parts of zinc sulfate, 2.0 parts of ferrous sulfate, and 0.5 parts of manganese sulfate are dissolved in a propanol solution of polyvinyl alcohol (PVA) and stirred evenly, the amount of polyvinyl alcohol is 4% of the total mass of the inorganic salt, and then the coating material is evenly attached to the surface of the trace element particles by spray drying to obtain a slow-release coated trace element) and stirred for 20 minutes, and finally 24 parts of organic fertilizer (biological organic fertilizer produced by Stanley Fertilizer Co., Ltd., label OF-301) are added and stirred for 15 minutes to obtain an acidic red soil conditioner based on secondary magnesium hydroxide.

[0049] Example 3

[0050] 28 parts of inferior magnesium hydroxide (magnesium hydroxide content of 82%, silicate and calcium compound content of 18%) and 9 parts of water-absorbing and fertilizer-retaining material (carboxymethyl cellulose produced by Luxi Chemical Group Co., Ltd., label CMC-200) were mixed and stirred at a speed of 480 rpm for 2 hours to obtain a mixed material, and then 28 parts of porous material (vermiculite produced by Luoyang Luanchuan Molybdenum Co., Ltd., label V-200) were added and stirred for 30 minutes, and then 5 parts of slow-release coated trace elements (boric acid 1.1 1.6 parts of zinc sulfate, 2.1 parts of ferrous sulfate, and 0.4 parts of manganese sulfate are dissolved in an ethanol solution of polyvinyl alcohol (PVA) and stirred evenly, the amount of polyvinyl alcohol is 5% of the total mass of the inorganic salt, and then the coating material is evenly attached to the surface of the trace element particles by spray drying to obtain a slow-release coated trace element) and stirred for 15 minutes, and finally 25 parts of organic fertilizer (humic acid organic fertilizer produced by New Hope Group, label HA-500) are added and stirred for 10 minutes to obtain an acidic red soil conditioner based on secondary magnesium hydroxide.

[0051] Example 4

[0052] Mix 32 parts of substandard magnesium hydroxide (magnesium hydroxide content is 78%, silicate and calcium compound content is 22%) with 11 parts of water-absorbing and fertilizer-retaining material (starch-based water-absorbing material produced by Hubei Yihua Group, label SB-300), and stir at a speed of 450 rpm for 2.5 h to obtain a mixed material. Then add 29 parts of porous material (perlite produced by Anhui Conch Group Co., Ltd., label EP-400) and continue to stir for 35 min, and then add 5 parts of slow-release coated trace elements (dissolve 0.9 part of boric acid, 1.5 parts of zinc sulfate, 2.3 parts of ferrous sulfate, and 0.6 part of manganese sulfate in an ethanol solution of polyvinyl alcohol PVA and stir evenly. The dosage of polyvinyl alcohol is 2% of the total mass of inorganic salts, and then the coating material is evenly attached to the surface of the trace element particles by spray drying to obtain slow-release coated trace elements) and stir for 20 min. Finally, add 26 parts of organic fertilizer (vermicompost produced by Sinochem Fertilizer Holdings Co., Ltd., label EW-700) and stir for 18 min to obtain an acidic red soil soil conditioner based on substandard magnesium hydroxide.

[0053] Example 5

[0054] Mix 29 parts of substandard magnesium hydroxide (magnesium hydroxide content is 81%, silicate content is 19%) with 10 parts of water-absorbing and fertilizer-retaining material (sodium polyacrylate produced by Wanhua Chemical Group Co., Ltd., label SPA-102), and react at a speed of 460 rpm for 2 h to obtain a mixed material. Then add 27 parts of porous material (zeolite produced by Aluminum Corporation of China Limited, label ZS-500) and continue to stir for 40 minutes, and then add 5 parts of slow-release coated trace elements (dissolve 1.0 part of boric acid, 1.4 parts of zinc sulfate, 2.0 parts of ferrous sulfate, and 0.5 part of manganese sulfate in a propanol solution of polyvinyl alcohol PVA and stir evenly. The dosage of polyvinyl alcohol is 3% of the total mass of inorganic salts, and then the coating material is evenly attached to the surface of the trace element particles by spray drying to obtain slow-release coated trace elements) and stir for 25 minutes. Finally, add 23 parts of organic fertilizer (commercial organic fertilizer produced by Jiangsu Zhonghai Chemical Fertilizer Group Co., Ltd., label OF-500) and stir for 15 min to obtain an acidic red soil soil conditioner based on substandard magnesium hydroxide.

[0055] Test the performance of the acidic red soil soil conditioner based on substandard magnesium hydroxide prepared in Examples 1-5. The test methods and results are as follows:

[0056] 1. Test the improvement effect of the soil conditioner prepared in Example 1 on the nutrient bowl soil:

[0057] Mix the soil conditioner prepared in Example 1 of the present invention with the nutrient bowl soil suitable for seedling raising or flower planting at a ratio of 1:4 to ensure that each component is evenly distributed and complete the improvement.

[0058] In the improved soil experiment, hydrangeas suitable for planting in Jiangxi and growing in nutrient pots were selected for testing. During the experiment, water was regularly applied to maintain appropriate humidity. The soil pH value was effectively adjusted within a short period. The root systems of the hydrangeas developed well, and the plants grew vigorously. The improved soil provided a stable nutrient supply, had good water retention and air permeability, significantly promoted the healthy growth of hydrangeas, with bright flower colors and a high flowering rate, demonstrating good adaptability and growth performance.

[0059] 2. Improvement effect of the soil conditioner prepared in Test Example 2 on vegetable garden soil:

[0060] The soil conditioner prepared in Example 2 of the present invention was evenly spread on the surface soil of the vegetable garden at a ratio of 1:5. A tilling tool was used to mix the conditioner with the surface soil to a depth of 15 - 20 cm to complete the improvement.

[0061] Chili seeds were sown in the improved soil. According to the growth requirements of chili, watering and fertilization were carried out in a timely manner. Magnesium hydroxide in the conditioner gradually increased the soil pH value and provided sufficient magnesium element to support the healthy growth of chili.

[0062] Effect: The acidity and alkalinity of the improved vegetable garden soil were effectively adjusted, the soil structure was significantly improved, the water and fertilizer retention capacity was enhanced, the chili plants grew vigorously with well-developed root systems, showing good drought tolerance and disease resistance. The improved soil was very suitable for vegetable planting, especially for the growth of chili.

[0063] 3. Improvement effect of the soil conditioner prepared in Test Example 3 on acidic red soil:

[0064] Before fruit tree planting, the soil conditioner prepared in Example 3 of the present invention was mixed with red soil at a ratio of 1:6, and the application was strengthened at tree holes or ditches; the mixed soil was plowed to a depth of 30 cm in the tree holes or ditches to ensure full contact between the conditioner and the soil.

[0065] Young seedlings of Akizuki pear fruit trees were planted in the improved soil. When planting, the tree holes were filled with the improved soil, gently compacted, and root-fixing water was poured. During the growth period of the fruit trees, organic fertilizers and water were appropriately supplemented in combination with fertilization. The conditioner provided a stable pH environment and necessary trace elements, promoting the healthy growth of the fruit trees.

[0066] Effect: The improved soil not only effectively improved the pH value of acidic red soil, but also significantly enhanced the soil's air permeability and water retention. The root system of Akizuki pears developed well, the fruit trees grew vigorously, and the fruit quality was greatly improved. The fruits in the second year after fruiting were large and plump, with smooth peels, increased sugar content, more intense flavor, and significantly improved market value of the fruits, demonstrating the dual improvement effects of the soil conditioner on fruit tree growth and fruit quality.

[0067] 4. Improvement effect of the soil conditioner prepared in Test Example 4 on lawn soil:

[0068] Before lawn planting, spread the conditioner evenly on the surface of the soil to be planted at a ratio of 1:5. Use a rake to shallowly mix the conditioner with the topsoil to a depth of 5 - 10 cm to loosen the soil structure and complete the improvement. Directly sow the lawn seeds in the improved soil, and then gently press the soil to make the seeds in close contact with the soil. Immediately water thoroughly after planting to keep the soil moist and promote the germination of lawn seeds and the rooting of the turf.

[0069] Effect: The improved soil provides a suitable growth environment for the lawn. The pH value is adjusted to a moderate level, the water retention of the soil is significantly enhanced, the lawn grows lushly, with strong roots and high turf density, and has strong trampling resistance, capable of withstanding long-term use and maintenance.

[0070] 5. Improvement effect of the soil conditioner prepared in Test Example 5 on flower planting soil:

[0071] In the flower planting area, mix the conditioner with acidic soil at a ratio of 1:5 and plow to a depth of 20 - 25 cm to complete the soil improvement. Plant camellias in the improved soil, water regularly to keep the soil moist, and supplement organic fertilizer appropriately to promote the growth and flowering of camellias.

[0072] Effect: The improved soil provides an ideal growth environment for acid-loving flowers. The soil pH value is moderate, and the water retention is significantly enhanced. Camellias grow vigorously, with bright flower colors, large and plump flowers, and a high flowering rate, showing excellent growth performance.

[0073] Test the parameters such as pH value, organic matter content, air permeability, water retention, trace element content, and soil microorganism quantity of the soil before and after improvement during the above test process. The test results are shown in Table 1 and Table 2.

[0074] Table 1 Comparison of soil parameters before and after modification

[0075]

[0076]

[0077] Comparison of the Number of Microorganisms in the Soil Before and After Modification

[0078]

[0079] 1. pH value: 7 days after the transformation, the pH values of all types of soil were adjusted to the neutral range (6.0 - 6.5), which is suitable for the growth of most plants.

[0080] 2. Organic matter content (%): The organic matter content of the transformed soil increased significantly, which helps to enhance soil fertility and promote the healthy growth of plants.

[0081] 3. Air permeability: After improvement, the air permeability of the soil was upgraded from "poor" or "very poor" to "good", which is beneficial to root respiration and growth.

[0082] 4. Water retention: The water retention of the improved soil was significantly enhanced, which can better retain water and reduce the impact of drought on plants.

[0083] 5. Trace element content: The contents of trace elements such as boron, zinc, iron, and manganese reached or approached the ideal range for plant growth after improvement.

[0084] 6. Numbers of bacteria, fungi, and actinomycetes: 7 days after the transformation, the number of microorganisms in the soil increased significantly, indicating a substantial increase in soil microbial activity, which helps the decomposition of organic matter and nutrient cycling, and further promotes plant growth.

[0085] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An acid red loam soil conditioner based on secondary magnesium hydroxide, characterized in that, It comprises raw materials in the following parts by mass: 27 - 33 parts of secondary magnesium hydroxide, 8 - 12 parts of water-absorbing and fertilizer-retaining material, 27 - 33 parts of porous material, 4 - 6 parts of slow-release coated trace elements, and 22 - 28 parts of organic fertilizer.

2. The acid red loam soil conditioner based on secondary magnesium hydroxide according to claim 1, characterized in that, The content of magnesium hydroxide in the secondary magnesium hydroxide is 76 - 84%, and the content of silicate is 16 - 24%.

3. The acid red soil conditioner based on secondary magnesium hydroxide according to claim 2, characterized in that, The water-absorbing and fertilizer-retaining material includes one or more of superabsorbent resin, carboxymethyl cellulose, and starch-based water-absorbing material.

4. An acid red loam soil conditioner based on secondary magnesium hydroxide according to claim 3, characterized in that, The porous material includes one or more of diatomite, vermiculite, and perlite.

5. A kind of acid red loam soil conditioner based on secondary magnesium hydroxide according to any one of claims 1 to 4, characterized in that, The preparation method of the slow-release coated trace elements is as follows: The slow-release coated trace elements are obtained by mixing coating materials, organic solvents, and inorganic salts and then drying. The coating material is polylactic acid and / or polyvinyl alcohol. The inorganic salts include 0.8 - 1.2 parts of boric acid, 1.2 - 1.8 parts of zinc sulfate, 1.7 - 2.3 parts of ferrous sulfate, and 0.35 - 0.65 parts of manganese sulfate by mass.

6. The acid red loam soil conditioner based on secondary magnesium hydroxide according to claim 5, characterized in that The organic fertilizer includes one or more of bio-organic fertilizer, humic acid organic fertilizer, earthworm compost, and commercial organic fertilizer.

7. A method for preparing an acid red soil conditioner based on secondary magnesium hydroxide according to any one of claims 1 to 6, characterized in that, It includes the following steps: 1) Mix the secondary magnesium hydroxide with the water-absorbing and fertilizer-retaining material to obtain a mixed material. 2) Mix the mixed material with the porous material, slow-release coated trace elements, and organic fertilizer to obtain an acid red soil soil conditioner based on secondary magnesium hydroxide.

8. The preparation method of an acid red loam soil conditioner based on secondary magnesium hydroxide according to claim 7, characterized in that, In step 1), the reaction time is 1.5 - 2.5 h, and the mixing temperature is 20 - 30 °C.

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