A mussel shell-based biomimetic slow-release conditioner as well as a preparation method and application thereof

Abstract

The application provides a mussel shell-based biomimetic slow-release conditioner and a preparation method and application thereof, relates to the technical field of agricultural soil improvement, and comprises natural mussel shell powder 20-30%, 300-450 DEG C calcined mussel shell powder 25-35%, and 600-700 DEG C calcined mussel shell powder 40-50%. The mussel shell-based biomimetic slow-release conditioner can continuously neutralize soil acidity, supply trace elements, improve rhizosphere microbial environment and relieve soil secondary salinization, so as to promote crop growth and improve yield and quality. The application adopts gradient puffing technology, which can not only continuously neutralize soil acidity, but also lock up nutrients due to the unique multilayer microporous structure, so as to provide trace elements and rhizosphere microbial environment for crops for a growth cycle, relieve soil secondary salinization, and avoid the drawbacks of traditional lime, such as easy hardening and strong drug power.

Description

Technical Field

[0001] This invention relates to the field of agricultural soil improvement technology, and in particular to a mussel shell-based biomineralized slow-release conditioner, its preparation method, and its application. Background Technology

[0002] Basic cations (Ca) in acidified soil 2+ Mg 2+ K + Significant loss of nutrients leads to decreased base saturation and weakened buffering capacity. Simultaneously, nutrients such as phosphorus and potassium are easily fixed or converted into forms difficult for plants to absorb, reducing nutrient availability. Acidic soils also increase the solubility of aluminum, manganese, and some heavy metals, which have toxic effects on crop roots and microbial communities, weakening soil ecological functions. Long-term acidification results in soil compaction, poor permeability, micronutrient imbalance, and reduced water and nutrient retention capacity, thereby inhibiting crop growth, reducing yield and quality, and impacting sustainable agricultural use. To alleviate soil acidification, Chinese scholars have developed various amendment materials, including lime, industrial by-products, and crop residues. Lime can increase soil pH and promote crop yield, but it migrates slowly in the soil, and excessive application can damage soil structure, leading to soil compaction and inducing secondary salinization. Industrial by-products can improve soil pH and base saturation, but some products have high heavy metal content, posing a pollution risk. Biochar and straw, among other organic materials, are effective in improving acidic soils, but their high cost and large application rates make them difficult to promote. Crop residues can provide nutrients and slightly increase soil pH, but their effectiveness is greatly affected by the original soil acidity, and in some cases, they can even exacerbate acidification. Therefore, it is necessary to develop new acidic soil conditioners that are easy to use, cost-effective, long-lasting, and environmentally friendly.

[0003] China is a major aquaculture country in the world, and shellfish farming has developed rapidly, with shellfish production reaching 1.458 million tons in 2019. 4 China's aquaculture industry accounts for over 60% of global aquaculture production. Currently, the main utilization is of the shellfish meat, while the shells, as a byproduct, account for over 80% of the shellfish's weight and have not yet been systematically utilized. Major farmed shellfish in my country include clams, oysters, mussels, scallops, and whelks. Their shells are rich in calcium carbonate and also contain trace elements such as zinc, iron, strontium, and manganese. After calcination, they form a porous structure with adsorption properties, which helps regulate soil pH, supply trace elements, and improve the microbial community. The calcium in the shells... 2+ It can react with heavy metal ions in the soil to form carbonate precipitates, purifying the soil, and react with Na+ on the soil colloid surface. + Mg 2+ Replacement makes soil colloids hydrophobic, improves structure and permeability, and achieves desalination and inhibits salt return. In recent years, research on shell powder for soil improvement in agriculture has gradually increased, but research on its supply of trace elements is still limited.

[0004] Existing research and published patents indicate that almost all shell materials currently used for improving acidic soils are oyster shell powder. For example, patent CN108822863A discloses calcined oyster shell powder and its use in rice cultivation, which can increase soil pH, reduce heavy metal (Cr, Mn, Tl) content, and improve microbial community structure; CN1245476C discloses a soil conditioner based on oyster shell powder, which promotes crop growth and improves yield and quality by improving soil microecology and fertilizer utilization; CN113174266A and CN106350073A also involve soil conditioners based on oyster shell powder, their preparation methods, and agricultural applications. Literature research shows that applying oyster shell powder to acidified orchards, paddy fields, rapeseed rotation systems, or vegetable cultivation can significantly increase soil pH, increase available nutrients, enhance enzyme activity, and improve microbial communities, thereby promoting crop growth and improving yield and quality. However, existing shell powder-based conditioners, especially highly alkaline calcined shell powder or lime-based materials, often suffer from problems such as excessively rapid initial neutralization reactions and insufficient persistence in the later stages, making it difficult to achieve long-term stable regulation of acidic soils and limiting the effectiveness of large-scale agricultural applications.

[0005] Therefore, there is an urgent need to study a highly active, structurally stable, and well-dispersible alkaline shell powder to fully realize the potential of shells in improving acidic soils, thereby continuously neutralizing soil acidity, supplying trace elements, improving the rhizosphere microbial environment, and alleviating secondary soil salinization, thus promoting crop growth and increasing crop yield and quality. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of existing acidic soil conditioners, the purpose of this invention is to provide a mussel shell-based biomineralization slow-release conditioner, its preparation method and application. By constructing a gradient expansion slow-release system, the gradual release of alkaline components and continuous regulation of soil acidity are achieved. The conditioner's unique microporous structure can lock in nutrients like a "reservoir", providing crops with trace elements and rhizosphere microbial environment for up to a growth cycle, while alleviating secondary soil salinization and avoiding the drawbacks of traditional lime's easy compaction and strong effects.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The present invention provides a mussel shell-based biomineralized slow-release conditioner, which, based on 100% by mass, comprises 20-30% natural mussel shell powder, 25-35% calcined mussel shell powder at 300-450℃, and 40-50% calcined mussel shell powder at 600-700℃.

[0008] Furthermore, based on the above technical solution, humic substances and bio-activators are wet-adsorbed in the multi-layered microporous structure of mussel shell powder calcined at 300-450℃. The humic substances include one or more of humic acid and fulvic acid. The biostimulant includes one or more of citric acid, glucose, and oligosaccharides.

[0009] The present invention also provides a method for preparing the mussel shell-based biomineralized slow-release conditioner as described above, comprising the following steps: S1: Pre-treat the mussel shells; S2: Use the pretreated mussel shells to prepare mussel shell powder calcined at 300-450℃; S3: Use the pretreated mussel shells to prepare mussel shell powder calcined at 600-700℃; S4: Use the pretreated mussel shells to prepare natural mussel shell powder; S5: Mix calcined mussel shell powder at 300-450℃, calcined mussel shell powder at 600-700℃, and natural mussel shell powder to obtain a mussel shell-based biomineralized slow-release conditioner.

[0010] Furthermore, based on the above technical solution, the preparation method of mussel shell powder calcined at 300-450℃ includes the following steps: S21: Place the pretreated mussel shells in a calcining furnace and heat them to 300-450℃ for 1-2 hours to allow the organic matter to decompose gradually and form mussel shells with a multi-layered microporous structure. S22: After the mussel shells with multi-layered microporous structures are naturally cooled to room temperature, they are placed in a solution containing humic substances and bio-activators for wet adsorption, and then dried and pulverized by blowing to obtain calcined mussel shell powder loaded with humic substances and bio-activators, i.e. calcined mussel shell powder at 300-450℃. And / or, in step S1, the pretreatment includes rinsing the surface of the mussel shell with purified water or deionized water to remove attached impurities.

[0011] Furthermore, based on the above technical solution, in step S22, the solution containing humic substances and biostimulants includes an aqueous solution of humic substances and an aqueous solution of biostimulants. The mass ratio of the aqueous solution of humic substances to the aqueous solution of biological stimulants is 1:0.5-3. The aqueous solution of humic substances has a concentration of 0.1-10 g / L and a pH of 5-8. The aqueous solution concentration of the biological stimulant is 0.5-10 g / L, and the pH is 5-8; And / or, in step S22, the solid-liquid ratio of the mussel shell with a multi-layered microporous structure to the solution containing humus and biostimulant is 1g:10mL-1g:50mL. And / or, in step S22, the temperature of the forced-air drying is 60-80℃, and the forced-air drying wind speed is 0.5-5m / s; And / or, in step S22, the pulverization is performed using a mechanical pulverizer or grinder; And / or, in step S22, the particle size of the mussel shell powder calcined at 300-450℃ is 100-200 mesh.

[0012] Furthermore, based on the above technical solution, the preparation method of mussel shell powder calcined at 600-700℃ includes the following steps: The pretreated mussel shells are placed in a calcining furnace and heated to 300-450℃, then to 600-700℃. After cooling, they are dried by forced air and pulverized to obtain calcined mussel shell powder at 600-700℃.

[0013] Furthermore, based on the above technical solution, the heat preservation time at 300-450℃ or 600-700℃ is 1-2 hours. And / or, the rate of heating to 600-700℃ is 8-15℃ / min; And / or, the temperature for blower drying is 60-80℃, and the blower drying velocity is 0.5-5m / s; And / or, the particle size of mussel shell powder calcined at 600-700℃ is 100-200 mesh.

[0014] Furthermore, based on the above technical solution, the preparation method of natural mussel shell powder includes the following steps: drying the pretreated mussel shells by forced air and then pulverizing them to obtain natural mussel shell powder; The temperature for blower drying is 60-80℃, and the blower drying velocity is 0.5-5m / s. The particle size of the crushed natural mussel shell powder is 100-200 mesh.

[0015] Furthermore, based on the above technical solution, in step S5, the mixing conditions include: a rotation speed of 20-35 rpm, a temperature of 25-30℃, and a mixing time of 15-30 min.

[0016] The present invention also provides the application of the mussel shell-based biomineralized slow-release conditioner prepared by the above-described method in crop cultivation.

[0017] The present invention provides a mussel shell-based biomineralized slow-release conditioner, its preparation method, and its application, which have at least the following beneficial effects: 1. This invention uses a combination of natural mussel shell powder, shell powder calcined at 300-450℃ and shell powder calcined at 600-700℃, and utilizes their differences in reactivity to achieve graded buffering and continuous stable regulation of soil pH.

[0018] 2. This invention uses a combination of natural mussel shell powder, shell powder calcined at 300-450℃, and shell powder calcined at 600-700℃, which have different dissolution and transformation mechanisms, and can continuously release Ca. 2+ and Fe 3+ Zn 2+ 、Sr 2+ It also provides trace elements and improves their availability by enhancing the soil cation exchange environment.

[0019] 3. This invention uses a multi-layered microporous structure of calcined shell powder at 300-450℃ to load humus and biostimulants, which slowly releases organic active substances, improves the rhizosphere microbial environment, and promotes the activity of beneficial rhizosphere microorganisms and the stability of soil microecology.

[0020] 4. This invention uses calcined shell powder at 300-450℃ in conjunction with humus and biological activators to passivate and buffer excess salt ions, reduce salt stress and improve soil structure, and effectively alleviate secondary soil salinization.

[0021] 5. The mussel shell-based biomineralized slow-release conditioner provided by this invention continuously neutralizes soil acidity, supplies trace elements, improves the rhizosphere microbial environment, and alleviates secondary soil salinization, thereby promoting crop growth and increasing crop yield and quality. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a SEM image of the natural mussel shell powder provided in Example 1 of the present invention; Figure 2 This is a SEM image of mussel shell powder calcined at 400℃ provided in Example 1 of the present invention; Figure 3 This is a SEM image of mussel shell powder calcined at 700℃ provided in Example 1 of the present invention; Figure 4 This is a SEM image of the natural mussel shell powder provided in Example 2 of the present invention; Figure 5This is a SEM image of mussel shell powder calcined at 350℃ provided in Example 2 of the present invention; Figure 6 This is a SEM image of mussel shell powder calcined at 600℃ provided in Example 2 of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0025] The endpoints and any values ​​of the ranges disclosed in this invention 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 in this invention.

[0026] According to a first aspect of the present invention, a mussel shell-based biomineralization slow-release conditioner is provided, comprising, by weight 100%, 20-30% (e.g., 22%, 24%, 26%, 28%, etc.) of natural mussel shell powder, 25-35% (e.g., 27%, 29%, 30%, 32%, 34%, etc.) of calcined mussel shell powder at 300-450℃ (e.g., 320℃, 340℃, 360℃, 380℃, 400℃, 420℃, 440℃, etc.), and 40-50% (e.g., 42%, 44%, 46%, 48%, etc.) of calcined mussel shell powder at 600-700℃ (e.g., 620℃, 640℃, 660℃, 680℃, etc.).

[0027] Specifically, the effect of shell powder on soil pH improvement and micronutrient absorption is significantly affected by the application rate, particle size, and calcination treatment. Natural shell powder is mildly alkaline, has a complete mineral structure, and can slowly regulate soil acidity. At the same time, it partially retains the bioavailability of micronutrients and contains a certain amount of organic matter, which helps to improve the physical and chemical properties of soil. The disadvantages are that the rate of neutralizing acidic soil is relatively slow, the release of micronutrients is unstable, and it cannot meet the rapid nutritional needs of crops during their vigorous growth period.

[0028] This invention significantly alters the physicochemical properties of seashell powder through calcination, thereby regulating its behavior in soil. Specifically, this invention constructs a three-tiered functional gradient puffing and slow-release system with "rapid response, continuous supply, and long-term stability" by compounding natural mussel shell powder (20-30%), calcined mussel shell powder at 300-450℃ (25-35%), and calcined mussel shell powder at 600-700℃ (40-50%). Calcined powder at 600-700℃ is rich in highly active calcium oxide, which is responsible for rapidly neutralizing soil acidity and raising the pH to a suitable range in a short period of time; calcined powder at 300-450℃, with its rich multi-layered microporous structure and weakly alkaline calcium carbonate, prolongs the release pathway of nutrients or functional substances, achieving sustained slow release in the medium term; natural mussel shell powder retains organically bound state and trace elements, providing biocompatibility and promoting the restoration of soil microecology; The three components form a hierarchical pore network of "macropore-mesopore-micropore" in terms of physical structure, exhibit a relay-style dissolution kinetic of "fast-medium-slow" in terms of chemical activity, and jointly create a microenvironment conducive to microbial colonization at the biological level. This synergistically achieves a gradual release of alkaline components from rapid release to long-term maintenance, ensuring rapid and continuous regulation of soil acidity while avoiding drastic pH fluctuations. It combines high efficiency, stability, and eco-friendliness, making it particularly suitable for improving highly acidic soils and for agricultural or ecological restoration scenarios that require a one-time application for long-term effectiveness.

[0029] If the calcination temperature is less than 300℃, the organic matter in the mussel shell powder will not decompose completely. Not only will it fail to form a multi-layered microporous structure, but some organic matter will also remain in the pores and block the channels. Furthermore, some trace elements will still be wrapped by organic matter and will not be exposed as effective active sites, thus affecting the adsorption and slow-release function of the conditioner. If the calcination temperature is in the range of 450-600℃, some micropores will shrink or collapse due to the temperature rise, resulting in a gradual decrease in the proportion of micropores and affecting the slow-release function of the conditioner. In addition, the mussel shell powder calcined in this temperature range also generates a small amount of CaO, which forms a small amount of composite oxides with the trace elements that have undergone solid-phase reaction. These compounds have improved chemical stability, but reduced surface active sites, and the adsorption capacity of the conditioner has decreased. If the calcination temperature of mussel shell powder is raised to above 700℃, the particles will become denser, the specific surface area will decrease, the neutralization rate will decrease, and the degree of solidification of trace elements will increase, making it difficult for plants to absorb them.

[0030] As an optional embodiment of the present invention, the multilayer microporous structure of the mussel shell powder calcined at 300-450℃ is wet-adsorbed with humic substances and biostimulants.

[0031] As an optional embodiment of the present invention, the humic substance includes one or more of humic acid and fulvic acid; The biostimulant includes one or more of citric acid, glucose, and oligosaccharides.

[0032] According to a second aspect of the present invention, a method for preparing the mussel shell-based biomineralized sustained-release conditioner as described above is provided, comprising the following steps: S1: Pre-treat the mussel shells; S2: Use the pretreated mussel shells to prepare mussel shell powder calcined at 300-450℃; S3: Use the pretreated mussel shells to prepare mussel shell powder calcined at 600-700℃; S4: Use the pretreated mussel shells to prepare natural mussel shell powder; S5: Mix calcined mussel shell powder at 300-450℃, calcined mussel shell powder at 600-700℃, and natural mussel shell powder to obtain a mussel shell-based biomineralized slow-release conditioner.

[0033] As an optional embodiment of the present invention, in step S1, the pretreatment includes rinsing the surface of the mussel shell with pure water or deionized water to remove attached impurities.

[0034] As an optional embodiment of the present invention, the method for preparing mussel shell powder by calcination at 300-450℃ includes the following steps: S21: Place the pretreated mussel shells in a calcining furnace and heat them to 300-450℃ for 1-2 hours to allow the organic matter to decompose gradually and form mussel shells with a multi-layered microporous structure. S22: After the mussel shells with multi-layered microporous structures are naturally cooled to room temperature, they are placed in a solution containing humic substances and bio-activators for wet adsorption, and then dried and pulverized by forced air to obtain calcined mussel shell powder loaded with humic substances and bio-activators, i.e., calcined mussel shell powder at 300-450℃.

[0035] Specifically, calcined mussel shell powder at 300-450℃ adsorbs humus and biostimulants, locking in nutrients like a "reservoir".

[0036] As an optional embodiment of the present invention, in step S22, the solution containing humic substances and biostimulants includes an aqueous solution of humic substances and an aqueous solution of biostimulants. The mass ratio of the aqueous solution of humus to the aqueous solution of the bio-activator is 1:0.5-3 (e.g., 1:1, 1:1.5, 1:2, 1:2.5, etc.), preferably 1:1-2; The concentration of humic substances in aqueous solutions is 0.1-10 g / L (e.g., 1 g / L, 2 g / L, 5 g / L, 7 g / L, 9 g / L, etc.), and the pH is 5-8 (e.g., 6, 7, etc.). Specifically, the concentration of the aqueous solution of humic acid is 0.5-10 g / L (e.g., 1 g / L, 2 g / L, 5 g / L, 7 g / L, 9 g / L, etc.), preferably 1-5 g / L, and the pH is 6-8; The aqueous solution of fulvic acid has a concentration of 0.1-5 g / L (e.g., 1 g / L, 2 g / L, 4 g / L, etc.), preferably 0.5-2 g / L, and a pH of 5-7; The aqueous solution concentration of the bio-activator is 0.5-10 g / L (e.g., 1 g / L, 2 g / L, 5 g / L, 7 g / L, 9 g / L, etc.), and the pH is 5-8; Specifically, the concentration of the aqueous solution of citric acid is 0.5-10 g / L (e.g., 1 g / L, 2 g / L, 5 g / L, 7 g / L, 9 g / L, etc.), preferably 1-3 g / L; The concentration of the glucose aqueous solution is 1-6 g / L (e.g., 2 g / L, 3 g / L, 4 g / L, 5 g / L, etc.), preferably 2-5 g / L; The concentration of the aqueous solution of oligosaccharides is 1-8 g / L (e.g., 2 g / L, 3 g / L, 5 g / L, 7 g / L, etc.), preferably 3-6 g / L; The oligosaccharide is chitosan oligosaccharide.

[0037] Specifically, in order to ensure loading efficiency, maintain pore openness and subsequent slow-release performance, the concentration of humic acid aqueous solution or the concentration of bio-activator aqueous solution needs to be controlled within the range defined in this invention. If either concentration is too high, it will lead to the formation of a thick organic coating layer on the surface of the calcined mussel shell, which will block the microporous structure and reduce the pore surface area and active sites. Furthermore, both excessively high and excessively low concentrations of biostimulants can cause side effects. Low concentrations result in insignificant activation effects, while excessively high concentrations can lead to abnormal proliferation of local microorganisms and excessive oxygen consumption.

[0038] In step S22, the solid-liquid ratio of the mussel shell with a multi-layered microporous structure to the solution containing humus and biostimulant is 1g:10-50mL (e.g., 1g:20mL, 1g:30mL, 1g:40mL, etc.), preferably 1g:20-40mL; Specifically, under the solid-liquid ratio specified in this invention, the shell powder can be fully submerged, and the solution components can enter the pore structure; the load can be effectively controlled; and subsequent drying is convenient.

[0039] In step S22, the conditions for wet adsorption include: a stirring speed of 100-300 rpm, a stirring temperature of 25-30℃, and a stirring time of 0.5-2 h; wet adsorption is used to ensure sufficient loading of humic substances and bio-activators in the multilayer microporous structure.

[0040] In step S22, the temperature of the blower drying is 60-80℃ and the blower drying wind speed is 0.5-5m / s to ensure that the hot air flows evenly and the powder does not fly away. In step S22, the pulverization is performed using a mechanical pulverizer or grinder; In step S22, the particle size of the mussel shell powder calcined at 300-450℃ is 100-200 mesh (e.g., 120 mesh, 140 mesh, 150 mesh, 170 mesh, 190 mesh, etc.).

[0041] Specifically, the multi-layered microporous structure formed by calcining shell powder at low temperatures of 300-450℃, through its high specific surface area, surface functional groups, and the large amount of Ca exposed on the surface, 2+ Ions can effectively adsorb humic components such as humic acid and fulvic acid, as well as biostimulants such as citric acid, glucose, and oligosaccharides, through complexation, electrostatic adsorption, and hydrogen bonding interactions. As an important soil organic matter, humic components have been experimentally verified to enhance soil aggregate stability, increase organic matter content and water stability, and improve soil cation exchange capacity (CEC), thereby improving soil physicochemical properties, including increasing porosity and water retention capacity, helping to reduce soil erosion and enhance the soil carbon pool (e.g., humic acid improves soil porosity and stability). Humic substances also complex micronutrients (such as Fe) 3+ Zn 2+ 、Sr 2+ (e.g., citric acid) can enhance the availability of these nutrients in the rhizosphere and improve root development and nutrient absorption efficiency by promoting the interaction between microorganisms and plant roots. Biostimulants such as citric acid, as low-molecular-weight organic acids, can chelate insoluble phosphate minerals in the soil, thereby promoting the release of plant-available phosphorus. Simultaneously, organic acids and oligosaccharides, as carbon sources easily utilized by microorganisms, can activate soil microbial communities, enhance microbial enzyme activity, and improve nutrient cycling. In this composite carrier, utilizing the slow-release characteristics of humus and biostimulants, a continuous passivation and buffering effect on salt ions is achieved through the synergistic effects of physical adsorption, chemical chelation, and biological regulation. This helps reduce the stress of salt on soil structure and plant growth, effectively alleviating secondary salinization caused by irrigation and fertilization in agricultural production. It contributes to the long-term stable improvement of soil structure, plant rhizosphere microbial environment, and ecological functions, exhibiting a multi-component synergistic soil conditioning effect.

[0042] As an optional embodiment of the present invention, the method for preparing the calcined mussel shell powder at 600-700℃ includes the following steps: The pretreated mussel shells are placed in a calcining furnace and heated to 300-450℃ to gradually decompose the organic matter. Then the temperature is raised to 600-700℃ to decompose calcium carbonate into highly active alkaline oxides, mainly calcium oxide. After cooling, the shells are dried by forced air and pulverized to obtain calcined mussel shell powder at 600-700℃.

[0043] As an optional embodiment of the present invention, the heat preservation time at 300-450℃ or 600-700℃ is 1-2 hours. The heating rate to 600-700℃ is 8-15℃ / min (e.g., 10℃ / min, 11℃ / min, 12℃ / min, 13℃ / min, 14℃ / min, etc.), preferably 10℃ / min. Slow heating helps to protect the pore structure.

[0044] As an optional embodiment of the present invention, in the method for preparing mussel shell powder by calcination at 600-700℃, the temperature of forced-air drying is 60-80℃ and the forced-air drying wind speed is 0.5-5m / s.

[0045] As an optional embodiment of the present invention, the particle size of the mussel shell powder calcined at 600-700℃ is 100-200 mesh (e.g., 120 mesh, 140 mesh, 150 mesh, 170 mesh, 190 mesh, etc.).

[0046] As an optional embodiment of the present invention, the preparation method of natural mussel shell powder includes the following steps: drying the pretreated mussel shells by forced air and then pulverizing them to obtain natural mussel shell powder.

[0047] As an optional embodiment of the present invention, in the preparation method of natural mussel shell powder, the temperature of the forced-air drying is 60-80℃ and the forced-air drying wind speed is 0.5-5m / s, so as to ensure that the hot air flows evenly and the powder does not fly away. The particle size of the crushed natural mussel shell powder is 100-200 mesh (e.g., 120 mesh, 140 mesh, 150 mesh, 170 mesh, 190 mesh, etc.).

[0048] As an optional embodiment of the present invention, in step S5, the mixing conditions include: a rotation speed of 20-35 rpm, a temperature of 25-30°C, and a mixing time of 15-30 min.

[0049] According to a third aspect of the present invention, the application of a mussel-based biomineralized slow-release conditioner prepared by the method described above or the method described above in the cultivation of crops is provided.

[0050] The mussel shell-based biomineralization slow-release conditioner provided by this invention, or the mussel shell-based biomineralization slow-release conditioner prepared by the method provided by this invention, is used in crop cultivation to continuously neutralize soil acidity, supply trace elements, improve the rhizosphere microbial environment, and alleviate secondary soil salinization, thereby promoting crop growth, increasing crop yield, and improving crop quality.

[0051] As an optional embodiment of the present invention, the crops include, but are not limited to, food crops (rice, wheat, corn), cash crops (rapeseed, cotton), horticultural and vegetable crops (leafy vegetables, solanaceous vegetables, melons), fruit trees (citrus, apples, grapes), and tea and other crops that are sensitive to soil acidity.

[0052] The present invention will be further described in detail below with reference to specific embodiments and comparative examples. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0053] Example 1 This embodiment provides a mussel shell-based biomineralized slow-release conditioner, which, based on 100% by mass, comprises 25% natural mussel shell powder, 25% calcined mussel shell powder at 400℃, and 50% calcined mussel shell powder at 700℃.

[0054] This embodiment also provides a method for preparing the above-mentioned mussel shell-based biomineralized slow-release conditioner, comprising the following steps: S1: Rinse the surface of the mussel shells with deionized water to remove impurities adhering to the surface of the mussel shells; S2: Use the pretreated mussel shells to prepare calcined mussel shell powder at 400℃: S21: Place the pretreated mussel shells in a calcining furnace and heat them to 400℃ for 1.5 hours to allow the organic matter to decompose gradually and form mussel shells with a multi-layered microporous structure. S22: After naturally cooling the mussel shells with multi-layered microporous structures to room temperature, they were placed in a solution containing humic substances and bio-activators for wet adsorption (wet adsorption time was 1 hour; stirring speed was 200 rpm at 25℃). Then, they were dried by forced air drying at 60℃ with a wind speed of 2 m / s, and finally pulverized using a mechanical pulverizer to obtain calcined mussel shell powder loaded with humic substances and bio-activators, i.e., calcined mussel shell powder at 400℃. Figure 2 As shown, it has a distinct multilayered microporous structure, with multiple interconnected layers of calcium carbonate sheets forming a network of open channels with a high specific surface area.

[0055] The solution containing humic substances and biostimulants includes an aqueous solution of humic substances in a mass ratio of 1:1 (humic acid is dissolved in water to obtain a solution with a concentration of 4 g / L, and then the pH is adjusted to 7) and an aqueous solution of biostimulants (citric acid is dissolved in water to obtain a solution with a concentration of 3 g / L). The solid-liquid ratio of the mussel shell with its multi-layered microporous structure to the solution containing humus and biostimulants was 1 g: 30 mL. The prepared calcined mussel shell powder at 400℃ was passed through a 150-mesh sieve, and the particle size of the calcined mussel shell powder at 400℃ was 150 mesh. S3: Use the pretreated mussel shells to prepare calcined mussel shell powder at 700℃: Pretreated mussel shells were placed in a calcining furnace and heated to 400℃, held for 1.5 hours to allow the organic matter to decompose gradually. The temperature was then increased to 700℃ at a rate of 10℃ / min and held for another 1.5 hours to decompose calcium carbonate into highly reactive alkaline oxides, primarily calcium oxide. The shells were then allowed to cool naturally to room temperature, followed by forced-air drying at 80℃ with a fan speed of 2 m / s. After pulverizing, the shells were passed through a 150-mesh sieve. The product passing through the sieve was 150-mesh calcined mussel shell powder at 700℃. Figure 3 As shown, its original layered microporous structure partially or completely collapsed due to high-temperature sintering, and the proportion of micropores and mesopores decreased significantly. Instead, micron-sized macropores were formed, which were mainly formed by the escape of carbon dioxide and were distributed in an irregular shape. S4: The pretreated mussel shells are dried by forced air drying at 80℃ with a wind speed of 5m / s, then pulverized and passed through a 150-mesh sieve. The product passing through the sieve is 150-mesh natural mussel shell powder. Figure 1 As shown, obvious calcium carbonate crystal layers can be seen. The overall structure is dense with very few pores and a low specific surface area, but it retains complete bioactivity and natural interface characteristics. S5: Mix calcined mussel shell powder at 400℃, calcined mussel shell powder at 700℃ and natural mussel shell powder (30 rpm, 25℃, 20 min) to obtain mussel shell-based biomineralized slow-release conditioner.

[0056] Example 2 This embodiment provides a mussel shell-based biomineralized slow-release conditioner, which, based on the mass of the mussel shell-based biomineralized slow-release conditioner as 100%, includes 30% natural mussel shell powder, 30% calcined mussel shell powder at 350℃, and 40% calcined mussel shell powder at 650℃.

[0057] This embodiment also provides a method for preparing the above-mentioned mussel shell-based biomineralized slow-release conditioner, comprising the following steps: S1: Rinse the surface of the mussel shells with deionized water to remove impurities adhering to the surface of the mussel shells; S2: Use the pretreated mussel shells to prepare calcined mussel shell powder at 350℃: S21: Place the pretreated mussel shells in a calcining furnace and heat them to 350℃ for 2 hours to allow the organic matter to decompose gradually and form mussel shells with a multi-layered microporous structure. S22: After naturally cooling the mussel shells with multi-layered microporous structures to room temperature, they were placed in a solution containing humic substances and bio-activators for wet adsorption (wet adsorption time was 1 hour; stirring speed was 200 rpm at 25℃). Then, they were dried by forced air drying at 70℃ with a wind speed of 4 m / s, and finally pulverized using a mechanical pulverizer to obtain calcined mussel shell powder loaded with humic substances and bio-activators, i.e., calcined mussel shell powder at 350℃. Figure 5 As shown.

[0058] The solution containing humic substances and biostimulants includes an aqueous solution of humic substances in a mass ratio of 1:2 (humic acid and fulvic acid are mixed in a mass ratio of 1:1 and dissolved in water to obtain a solution with a concentration of 2 g / L, and then the pH is adjusted to 6) and an aqueous solution of biostimulants (chitosan oligosaccharide is dissolved in water to obtain a solution with a concentration of 3 g / L). The solid-liquid ratio of the mussel shell with its multi-layered microporous structure to the solution containing humus and biostimulants was 1 g: 35 mL. The prepared calcined mussel shell powder at 350℃ was passed through a 200-mesh sieve, and the particle size of the calcined mussel shell powder at 400℃ that passed through the sieve was 200 mesh. S3: Use the pretreated mussel shells to prepare calcined mussel shell powder at 650℃: The pretreated mussel shells were placed in a calcining furnace and heated to 350℃, held for 2 hours to allow the organic matter to gradually decompose. The temperature was then increased to 650℃ at a rate of 10℃ / min and held for 2 hours to decompose calcium carbonate into highly reactive alkaline oxides, primarily calcium oxide. The mixture was then naturally cooled to room temperature and dried by forced air drying at 70℃ with a wind speed of 4 m / s. After pulverizing, the shells were passed through a 200-mesh sieve. The product passing through the sieve was the 200-mesh calcined mussel shell powder at 650℃. Figure 6 As shown; S4: The pretreated mussel shells are dried by forced air drying at 80℃ with a wind speed of 5m / s, then pulverized and passed through a 200-mesh sieve. The product passing through the sieve is 200-mesh natural mussel shell powder. Figure 4 As shown; S5: Mix calcined mussel shell powder at 350℃, calcined mussel shell powder at 650℃ and natural mussel shell powder (30 rpm, 25℃, 20 min) to obtain mussel shell-based biomineralized slow-release conditioner.

[0059] Experimental Example 1: Application Example in Rice Experimental Field (1) Experimental plots and conditions The experiment was conducted in acidic paddy fields in Xinjian District, Nanchang City, Jiangxi Province, with a soil pH of 4.8. Each field group had an area of ​​1 mu (approximately 0.067 hectares), and the rice variety was "Xiangyou 12". All fields were treated with conventional base fertilizer (nitrogen:phosphorus:potassium = 120:60:60 kg / mu), and irrigation and field management were kept consistent.

[0060] (2) Application of mussel shell-based biomineralization slow-release conditioner The mussel shell-based biomineralization slow-release conditioner prepared in Example 1 was applied to the soil as a composite mussel shell powder group. Simultaneously, blank control group, lime powder group, natural mussel shell powder group, calcined mussel shell powder group at 400℃, calcined mussel shell powder group at 700℃, calcined mussel shell powder group at 800℃, and calcined mussel shell powder group at 500℃ were also set up. The blank control group received no soil treatment. The lime powder group uses lime powder applied to the soil; The natural mussel shell powder group refers to the soil in which only the natural mussel shell powder prepared in Example 1 was applied; The 400℃ calcined mussel shell powder group refers to soil in which only the 400℃ calcined mussel shell powder prepared in Example 1 was applied; The 700℃ calcined mussel shell powder group refers to soil in which only the 700℃ calcined mussel shell powder prepared in Example 1 was applied; The 800℃ calcined mussel shell powder group refers to replacing the 700℃ calcined mussel shell powder in the composite mussel shell powder group with 800℃ calcined mussel shell powder (the temperature of the second heating in step S3 is 800℃, and the other steps and technical parameters are the same as in Example 1), and the other components are the same as in the composite mussel shell powder group. The 500℃ calcined mussel shell powder group refers to replacing the 400℃ calcined mussel shell powder in the composite mussel shell powder group with 500℃ calcined mussel shell powder (the temperature of the heating in step S21 is 500℃, and the other steps and technical parameters are the same as in Example 1), and the other components are the same as in the composite mussel shell powder group.

[0061] The application rate for each group is set at 300 kg / mu, which should be evenly spread on the surface layer of the tilled field (0-20 cm) and thoroughly mixed with the soil. Irrigation should be carried out 7 days after application to promote soil response.

[0062] (3) Birth management Rice is managed according to conventional methods, including tillering, jointing, and heading. The field is kept at a suitable moisture level, and common diseases and pests are prevented and controlled.

[0063] (4) Harvesting and yield measurement The rice harvest period is about 130 days. Soil samples of 0-20cm and fresh soil samples from the rhizosphere are collected during the rice harvest period. Air-dried soil is used for soil physicochemical properties and nutrient determination, while fresh soil is used for microbial index determination.

[0064] Soil pH was determined according to HJ962-2018 "Determination of Soil pH by Potentiometric Method"; Soil water-soluble salts and related ions were determined according to the NY / T1121 series of methods; Soil water-stable aggregates were determined by the wet sieving method according to NY / T1121.19-2008 "Soil Testing Part 19: Determination of the Composition of Soil Water-Stable Macroaggregates"; Exchangeable Ca and Mg were determined according to NY / T1121.13-2006; Available Fe and Zn were determined using the DTPA extraction method according to NY / T890-2004; Sr was determined by ICP-MS; soil microbial biomass carbon and nitrogen were determined according to GB / T39228-2020 "Determination of Soil Microbial Biomass - Fumigation Extraction Method"; Culturable bacteria, fungi, and actinomycetes were determined using the dilution plate colony count method. Rice root activity was determined using the TTC reduction method. The number of effective ears, seed setting rate, thousand-grain weight, and theoretical yield were determined and calculated using the general methods for yield measurement in agricultural production.

[0065] ① Soil pH: Air-dried soil samples passed through a 2mm sieve were used to prepare a suspension (10.0g soil + 25mL CO2-free water) at a water-to-soil ratio of 2.5:1. The suspension was stirred vigorously for 2 minutes, allowed to stand for 30 minutes, and then measured with a pH meter.

[0066] ②EC (Electrical Conductivity): Weigh an air-dried and sieved soil sample, prepare a soil water extract according to standard methods, and measure its electrical conductivity at 25℃. The result is expressed as mS / cm.

[0067] ③ Soluble Na+: The Na+ content in the soil water extract was determined. + The atomic absorption spectrometry method was used for determination, and the concentration was converted to cmol / kg based on the extraction volume and soil sample mass.

[0068] ; In the formula, c represents the Na content in the extract. + Concentration, in mmol / L; V is the volume of the extract, in L; m is the sample weight, in kg.

[0069] ④ESP (Exchangeable Sodium Percentage): Exchangeable Na was determined using the ammonium acetate-ammonium hydroxide exchange-flame photometry method, and CEC was determined using the ammonium acetate method. ESP was calculated using the following formula: ; ⑤ Water-stable aggregates: Take air-dried aggregate samples and classify them according to the wet sieving method in NY / T1121.19-2008. Calculate the content of water-stable aggregates >0.25mm. The formula for expressing the percentage of water-stable aggregates >0.25mm is as follows: ; Where, m ＞0.25 For the dry mass on a sieve >0.25mm, m s m0 represents the mass of the corresponding sand grain size, and m0 represents the total dry mass of the soil sample.

[0070] ⑥ Exchangeable Ca and Mg: According to NY / T1121.13-2006 "Soil Testing Part 13: Determination of Exchangeable Calcium and Magnesium in Soil", ammonium acetate exchange was used, and the Ca and Mg in the leachate were determined by atomic absorption spectrometry and other methods.

[0071] ; ; In the formula, ρ represents the mass concentration of Ca or Mg in the extract (mg / L), V represents the volume of the extract (L), and m represents the mass of the soil (kg).

[0072] Exchangeable Ca and Mg are mainly used for inter-treatment comparisons and fertilizer supply characteristic analysis. Their abundance or deficiency can be interpreted in conjunction with regional farmland quality grading standards or crop critical values. This experiment mainly focuses on the relative differences among treatments.

[0073] ⑦Fe, Zn, Sr: The contents of available Zn and Fe in the soil were determined by DTPA extraction, referring to the method in NY / T890-2004. The element concentrations in the extract were determined by ICP-OES, and the results are expressed in mg / kg.

[0074] ; Where X is the available Fe or Zn content in the soil, ρ is the elemental mass concentration in the extract (mg / L), V is the fixed volume (L), f is the dilution factor, and m is the soil sample mass (kg).

[0075] The Sr content was determined according to the standard summary of the determination methods for Fe and Zn.

[0076] ⑧ Bacterial, fungal, and actinomycete counts: Take 10.0g of fresh rhizosphere soil, add 90mL of sterile water, shake to prepare a soil suspension, and perform a 10-fold serial dilution. Bacteria were cultured on beef extract peptone medium at 28–30℃ for 2–3 days; fungi were cultured on Martin's medium at 28℃ for 3–5 days; and actinomycetes were cultured on Gao's No. 1 medium at 28℃ for 5–10 days. Plates with colony counts of 30–300 were used for counting, and the results are expressed as CFU / g dry soil.

[0077] ; Where C is the average colony count, D is the dilution factor, V is the inoculation volume (mL), and W is the dry soil mass corresponding to the inoculation (g). ⑨ MBC and MBN: Soil microbial biomass carbon and nitrogen were determined using the chloroform fumigation-0.5 mol / L K2SO4 extraction method. Organic carbon and total nitrogen in the extracts of fumigated and non-fumigated samples were measured separately, and MBC and MBN were calculated using the difference method.

[0078] ; ; Among them, C f C nf Organic carbon in the extracts of fumigated and unfumigated samples, respectively; N f N nf These represent the total nitrogen in the extracts of fumigated and non-fumigated samples, respectively; the commonly used conversion factor k EC =0.45, k EN =0.54 ⑩ Rice growth and yield indicators Root activity (TTC, μg / g·h): Fresh root samples were taken, washed, cut into pieces, weighed, and TTC-phosphate buffer was added. The reaction was carried out at 37℃ in the dark for a certain time, and sulfuric acid was added to terminate the reaction. The reduction product TTC-formazan was extracted with ethyl acetate or ethanol, and the absorbance was measured at 485 nm. The TTC reduction amount was calculated according to the standard curve. The results are expressed as μg / (g·h).

[0079] ; Where ρ is the concentration of TTC reduction product obtained from the standard curve, V is the volume of the extract, f is the dilution factor, m is the fresh weight of the root, and t is the reaction time.

[0080] Effective number of spikelets (plants / m) 2 ): During the maturity period, the number of ears with normal grain filling and meeting the effective standard is counted within the sample plot area, and then converted into the number of ears per unit area.

[0081] Seed setting rate (%): Randomly select representative rice panicles and count the total number of grains and the number of filled grains.

[0082] 1000-grain weight (g): Take a random number of plump rice grains, count 1000 grains, dry them to constant weight or weigh them after converting to standard moisture content.

[0083] Dry matter per ear (g / plant): Representative plants were selected at harvest time, and the ear was dried to constant weight, and the result was calculated based on the number of plants.

[0084] Yield (kg / mu): Yield was measured using the quadrat actual harvest method and converted to 13.5% standard moisture content. Where W is the actual weight of rice harvested per quadrat (kg), and S is the quadrat area (m²). 2 Then calculate based on the standard moisture content.

[0085] ; (5) Application results Table 1. Changes in soil pH in each group of paddy fields Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a, b, c, d, e, and f only indicate different significance groups, labeled in descending order of mean.

[0086] As shown in Table 1, compared with the blank control group, the soil pH of the composite mussel shell powder group increased steadily throughout the growth period, slowly rising from 4.80±0.03 to 6.04±0.06 at harvest, demonstrating a continuous and stable slow-release neutralization capacity. The lime powder group and the 700℃ calcined mussel shell powder group showed a faster initial pH increase, which easily led to problems such as localized alkalization and sudden changes in the root environment. The lime powder group reached its highest pH of 6.10±0.05 at 60 days, but decreased at harvest, indicating insufficient sustainability. The natural mussel shell powder and 400℃ calcined mussel shell powder groups showed a moderate sustained pH increase. The 500℃ calcined mussel shell powder group experienced a decrease in pH inhibition capacity due to the collapse of some micropores caused by temperature rise, resulting in insufficient sustainability. The 800℃ calcined mussel shell powder group experienced a decrease in the neutralization rate at 60 days due to the dense sintering of particles, also indicating insufficient sustainability.

[0087] Table 2 Soil salinization indices at harvest time for each group of paddy fields Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a, b, c, and d only indicate different significance groups, labeled in descending order of mean.

[0088] As shown in Table 2, compared with the blank control group, the compound mussel shell powder group significantly increased soil water-stable aggregates while maintaining low EC and low Na content. + The low ESP (Effective Chemical Spray) reduced the risk of secondary salinization; in contrast, the lime powder group and the 700℃ calcined mussel shell powder group significantly reduced soil water-stable aggregates, while increasing EC (Effective Chemical Spray) and Na (Na). +Both ESP and calcined mussel shell powder contribute to the risk of secondary salinization; the effects of natural mussel shell powder and calcined mussel shell powder at 400℃ are moderate. Although the calcined mussel shell powder at 500℃ and 800℃ still maintain certain advantages of the composite system, their effects on salt buffering and agglomeration maintenance are weaker than those of the composite mussel shell powder group because calcination at 500℃ causes partial collapse of the pore structure and calcination at 800℃ causes particle densification. The overall effect is between the composite group and the single calcined group.

[0089] Table 3. Soil available calcium, magnesium, and trace element in each group of paddy fields at harvest time. Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a, b, c, and d only indicate different significance groups, labeled in descending order of mean.

[0090] As shown in Table 3, compared with the blank control group, the available calcium in the soil of the lime powder group and the 700℃ calcined mussel shell powder group was at a moderate level during the harvest period, indicating that its alkaline components had been rapidly consumed in the early stage. Furthermore, the 700℃ calcination of mussel shell powder solidified trace elements into oxides or solid solutions, failing to provide available magnesium and trace elements Sr and Zn. While the composite mussel shell powder did not produce a sudden surge in calcium, it continuously provided calcium, magnesium, and various trace elements throughout the entire growth period, demonstrating a significant slow-release nutrient supply advantage. The natural mussel shell powder and the 400℃ calcined mussel shell powder group showed moderate effects. The 500℃ and 800℃ calcined mussel shell powder groups showed weaker synergistic release effects of calcium, magnesium, and trace elements than the composite mussel shell powder group, with overall performance falling between the composite group and the single calcination group.

[0091] Table 4. Rhizosphere microbial indices of rice paddies at harvest time for each group. Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a, b, c, and d only indicate different significance groups, labeled in descending order of mean.

[0092] As shown in Table 4, compared with the blank control group, the number of rhizosphere bacteria and actinomycetes, as well as the carbon and nitrogen levels of microorganisms, were significantly increased in both the 400℃ calcined mussel shell powder group and the composite mussel shell powder group, while the number of fungi was significantly decreased. Both groups showed similar promoting trends, which is related to their multi-layered microporous structure's adsorption and slow-release effect on organic matter, providing attachment and buffering space for microorganisms. Under improved pH conditions in acidic soil, the number of bacteria and actinomycetes increased significantly, while the number of fungi decreased relatively, indicating a shift in the rhizosphere microbial community from a fungi-dominated structure under acidic conditions to a bacteria-actinomycete-dominated structure. The composite mussel shell powder group showed higher overall levels across all indicators, demonstrating further advantages in slow-release stability and rhizosphere ecological regulation. The lime powder group, natural mussel shell powder, and the 700℃ calcined mussel shell powder group showed moderate effects. The 500℃ and 800℃ calcined mussel shell powder groups maintained the promoting advantage of the composite system on the rhizosphere microecology, with overall effects falling between the composite group and the single calcination group.

[0093] Table 5. Rice growth and yield indicators at harvest time in each group of paddy fields. Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a and b only indicate different significance groups, labeled in descending order of mean.

[0094] As shown in Table 5, compared with the blank control group, the lime powder group and various mussel shell powder groups all promoted rice growth and yield to varying degrees, with improvements in root activity, effective panicle number, seed setting rate, thousand-grain weight, panicle dry matter, and yield. Among them, the compound mussel shell powder group showed the most significant effect, with a rice yield of 5500±180 kg / mu, significantly higher than the 400℃ calcined mussel shell powder group and other treatment groups. Although the 400℃ calcined mussel shell powder group had a significant promoting effect, all indicators were still lower than the compound mussel shell powder group. The lime powder group, the 700℃ calcined mussel shell powder group, and the natural shell powder group also improved growth indicators and yield, but their overall levels were lower than the compound mussel shell powder group and the 400℃ calcined mussel shell powder group. The 500℃ calcined mussel shell powder group and the 800℃ calcined mussel shell powder group showed performance between the compound group and the single calcination group.

[0095] (6) Conclusion This invention provides a mussel shell-based biomineralized slow-release conditioner that not only continuously neutralizes acidic soil and avoids the problems of traditional lime such as "strong chemical effect, easy acidification, and easy compaction," but also relies on its microporous structure to achieve slow nutrient release and microecological regulation. It shows significant advantages in improving the structure of acidic paddy soil, alleviating secondary salinization, and increasing rice yield and stability. It is suitable for long-term improvement and safe production in acidic paddy fields.

[0096] Experimental Example 2: Application Example in Rapeseed Experimental Field (1) Experimental plots and conditions The experiment was conducted in a greenhouse acidic rapeseed field in Wangcheng District, Changsha City, Hunan Province. The soil pH was 5.0, and the field area was 0.8 mu per group. The rapeseed variety was "Huanan Zaoyou No. 2". Conventional base fertilizer (N:P:K=80:40:40kg / mu) was applied, and the soil was kept moist by irrigation. The management was consistent.

[0097] (2) Application of mussel shell-based biomineralization slow-release conditioner The mussel shell-based biomineralized slow-release conditioner prepared in Example 1 was applied to the soil as a composite mussel shell powder group. Simultaneously, blank control group, lime powder group, natural mussel shell powder group, calcined mussel shell powder group at 400℃, calcined mussel shell powder group at 700℃, calcined mussel shell powder group at 800℃, and calcined mussel shell powder group at 500℃ were set up (grouping as in Example 1). The application rate for each group was set at 240 kg / mu, evenly spread on the surface layer (0-20 cm) of the tilled field and thoroughly mixed with the soil. Irrigation was carried out 5 days after application to promote soil response.

[0098] (3) Birth management Throughout the entire growth period of rapeseed, maintain reasonable field water management, prevent and control diseases and pests in a timely manner, and manage the plants to ensure ventilation and light penetration.

[0099] (4) Harvesting and indicator measurement The harvest period is about 180 days. During the rapeseed harvest period, soil samples of 0-20cm and fresh soil samples from the rhizosphere are collected. The air-dried soil is used for soil physicochemical properties and nutrient determination, and the fresh soil is used for microbial index determination. The testing methods are the same as in Experiment 1.

[0100] (5) Application results Table 6. Soil pH changes in rapeseed fields for each group. Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a, b, c, d, e, and f only indicate different significance groups, labeled in descending order of mean.

[0101] The effects of soil pH change index in each group of rapeseed fields were consistent with the results in Experiment Example 1.

[0102] Table 7 Soil salinization indices at harvest time for each group of rapeseed fields Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a, b, and c only indicate different significance groups, labeled in descending order of mean.

[0103] The results of soil salinization index at the harvest period in each group of rapeseed fields were consistent with those in Experiment Example 1.

[0104] Table 8. Soil available calcium, magnesium, and trace element in rapeseed fields at harvest time for each group. Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a, b, c, d, and e only indicate different significance groups, labeled in descending order of mean.

[0105] The results of the available calcium, magnesium and trace element indicators in the soil at the harvest period of each group of rapeseed fields were consistent with those in Experiment Example 1.

[0106] Table 9. Soil rhizosphere microbial indices at harvest time for each group of rapeseed fields Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a, b, c, and d only indicate different significance groups, labeled in descending order of mean.

[0107] The effects of soil rhizosphere microbial indicators at the harvest period in each group of rapeseed fields were consistent with those in Example 3.

[0108] Table 10 Rapeseed growth and yield indicators at harvest time for each group of rapeseed fields The number of branches refers to the number of effective branches per rapeseed plant at maturity. Representative plants were randomly selected from each treatment before harvest, and the number of effective branches per plant was counted. The average value was taken, and the results were expressed as "branches / plant".

[0109] Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a, b, and c only indicate different significance groups, labeled in descending order of mean.

[0110] The results of rapeseed growth and yield indicators at the harvest period in each group of rapeseed fields were consistent with those in Experiment Example 1.

[0111] (6) Conclusion Mussel shell-based biomineralized slow-release conditioner not only continuously neutralizes acidic soil, avoiding the problems of traditional lime such as "strong chemical effect, easy acidification, and easy compaction", but also relies on its microporous structure to achieve slow release of nutrients and micro-ecological regulation. It shows significant advantages in improving the soil structure of acidic rapeseed fields, alleviating secondary salinization, and increasing rapeseed yield, oil extraction rate and stability. It is suitable for long-term improvement and safe production of acidic rapeseed fields.

[0112] Experimental Example 3: Application Example in a Melon Experimental Field (1) Experimental plots and conditions The experiment was conducted in a greenhouse acidic melon field in Putuo District, Zhoushan City, Zhejiang Province. The soil pH was 5.2, and each field area was 0.5 mu. The melon variety was "Golden Melon". Conventional base fertilizer (N:P:K=12:10:15kg / mu) was applied, and irrigation was kept uniform.

[0113] (2) Application of mussel shell-based biomineralization slow-release conditioner The mussel shell-based biomineralized slow-release conditioner prepared in Example 2 was applied to the soil as the composite mussel shell powder group. Simultaneously, a blank control group, a lime powder group, a natural mussel shell powder group, a 350℃ calcined mussel shell powder group, and a 650℃ calcined mussel shell powder group were set up. The blank control group received no soil treatment. The lime powder group used lime powder applied to the soil. The natural mussel shell powder group used the natural mussel shell powder prepared in Example 2. The 350℃ calcined mussel shell powder group used only the 350℃ calcined mussel shell powder prepared in Example 2. The 650℃ calcined mussel shell powder group used only the 650℃ calcined mussel shell powder prepared in Example 2. The application rate for each group was set at 240 kg / mu, evenly spread on the top 0-20 cm of the tilled field and thoroughly mixed with the soil. Irrigation was carried out 5 days after application to promote soil reaction.

[0114] (3) Birth management Melons should be cultivated under plastic film, with regular thinning of flowers and fruits to maintain field moisture and timely prevention and control of pests and diseases.

[0115] (4) Harvesting and indicator measurement The harvest period is about 70 days, and the soil physicochemical properties, nutrient retention and slow release characteristics, rhizosphere microorganisms, melon yield and quality, and other indicators are measured.

[0116] (5) Application results Table 11 Changes in soil pH in each group of melon fields Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a, b, c, and d only indicate different significance groups, labeled in descending order of mean.

[0117] The changes in soil pH in each group of melon fields were consistent with the results in Experiment 1 and Experiment 2.

[0118] Table 12 Soil salinization indices at harvest time for each group of melon fields Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a, b, and c only indicate different significance groups, labeled in descending order of mean.

[0119] The effects of soil salinization index on the melon fields in each group during the harvest period were consistent with the results in Experiment 1 and Experiment 2.

[0120] Table 13. Soil available calcium, magnesium and trace element in each group of melon fields at harvest time Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a, b, c, and d only indicate different significance groups, labeled in descending order of mean.

[0121] The results of soil available calcium, magnesium and trace element indicators at the harvest period in each group of melon fields were consistent with those in Experiment 1 and Experiment 2.

[0122] Table 14. Soil rhizosphere microbial indices at harvest time for each group of melon fields Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a, b, c, and d only indicate different significance groups, labeled in descending order of mean.

[0123] The results of soil rhizosphere microbial indicators at the harvest period in each group of melon fields were consistent with those in Experiment 1 and Experiment 2.

[0124] Table 15. Melon growth, yield, and quality indicators at harvest time for each group of melon fields. Different letters indicate significant differences between treatments in the same column (P < 0.05); the same letter or containing the same letter indicates no significant difference (P > 0.05); the letters a, b, and c only indicate different significance groups, labeled in descending order of mean.

[0125] The results of the melon growth, yield and quality indicators of each group of melon fields at the harvest period were consistent with those of Experiment 1 and Experiment 2.

[0126] (6) Conclusion Mussel shell-based biomineralization slow-release conditioner not only continuously neutralizes acidic soil, avoiding the problems of traditional lime such as "strong chemical effect, easy acidification, and easy compaction", but also relies on its microporous structure to achieve slow release of nutrients and micro-ecological regulation. It shows significant advantages in improving the soil structure of acidic melons, alleviating secondary salinization, increasing melon yield, and improving the flavor, quality and stability of melons. It is suitable for long-term improvement and safe production in acidic melon fields.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mussel shell-based biomineralized slow-release conditioner, characterized in that, The herringbone-based biomineralized slow-release conditioner comprises, by weight, 20-30% natural herringbone powder, 25-35% calcined herringbone powder at 300-450℃, and 40-50% calcined herringbone powder at 600-700℃.

2. The mussel shell-based biomineralized slow-release conditioner according to claim 1, characterized in that, The multi-layered microporous structure of mussel shell powder calcined at 300-450℃ wet adsorption of humus and bio-activators was achieved. The humic substances include one or more of humic acid and fulvic acid. The biostimulant includes one or more of citric acid, glucose, and oligosaccharides.

3. A method for preparing a mussel shell-based biomineralized slow-release conditioner as described in any one of claims 1-2, characterized in that, Includes the following steps: S1: Pre-treat the mussel shells; S2: Use the pretreated mussel shells to prepare mussel shell powder calcined at 300-450℃; S3: Use the pretreated mussel shells to prepare mussel shell powder calcined at 600-700℃; S4: Use the pretreated mussel shells to prepare natural mussel shell powder; S5: Mix calcined mussel shell powder at 300-450℃, calcined mussel shell powder at 600-700℃, and natural mussel shell powder to obtain a mussel shell-based biomineralized slow-release conditioner.

4. The method for preparing the mussel shell-based biomineralized slow-release conditioner according to claim 3, characterized in that, The preparation method of mussel shell powder calcined at 300-450℃ includes the following steps: S21: Place the pretreated mussel shells in a calcining furnace and heat them to 300-450℃ for 1-2 hours to allow the organic matter to decompose gradually and form mussel shells with a multi-layered microporous structure. S22: After the mussel shells with multi-layered microporous structures are naturally cooled to room temperature, they are placed in a solution containing humic substances and bio-activators for wet adsorption, and then dried and pulverized by blowing to obtain calcined mussel shell powder loaded with humic substances and bio-activators, i.e. calcined mussel shell powder at 300-450℃. And / or, in step S1, the pretreatment includes rinsing the surface of the mussel shell with purified water or deionized water to remove attached impurities.

5. The method for preparing the mussel shell-based biomineralized slow-release conditioner according to claim 4, characterized in that, In step S22, the solution containing humic substances and biostimulants includes an aqueous solution of humic substances and an aqueous solution of biostimulants. The mass ratio of the aqueous solution of humic substances to the aqueous solution of biological stimulants is 1:0.5-3. The aqueous solution of humic substances has a concentration of 0.1-10 g / L and a pH of 5-8. The aqueous solution concentration of the biological stimulant is 0.5-10 g / L, and the pH is 5-8; And / or, in step S22, the solid-liquid ratio of the mussel shell with a multi-layered microporous structure to the solution containing humus and biostimulant is 1g:10mL-1g:50mL. And / or, in step S22, the temperature of the forced-air drying is 60-80℃, and the forced-air drying wind speed is 0.5-5m / s; And / or, in step S22, the pulverization is performed using a mechanical pulverizer or grinder; And / or, in step S22, the particle size of the mussel shell powder calcined at 300-450℃ is 100-200 mesh.

6. The method for preparing the mussel shell-based biomineralized slow-release conditioner according to claim 3, characterized in that, The preparation method of mussel shell powder calcined at 600-700℃ includes the following steps: The pretreated mussel shells are placed in a calcining furnace and heated to 300-450℃, then to 600-700℃. After cooling, they are dried by forced air and pulverized to obtain calcined mussel shell powder at 600-700℃.

7. The method for preparing the mussel shell-based biomineralized slow-release conditioner according to claim 6, characterized in that, The heat preservation time at 300-450℃ or 600-700℃ is 1-2 hours. And / or, the rate of heating to 600-700℃ is 8-15℃ / min; And / or, the temperature for blower drying is 60-80℃, and the blower drying velocity is 0.5-5m / s; And / or, the particle size of mussel shell powder calcined at 600-700℃ is 100-200 mesh.

8. The method for preparing the mussel shell-based biomineralized slow-release conditioner according to claim 3, characterized in that, The preparation method of natural mussel shell powder includes the following steps: drying the pretreated mussel shells by forced air and then pulverizing them to obtain natural mussel shell powder; The temperature for blower drying is 60-80℃, and the blower drying velocity is 0.5-5m / s. The particle size of the crushed natural mussel shell powder is 100-200 mesh.

9. The method for preparing the mussel shell-based biomineralized slow-release conditioner according to claim 3, characterized in that, In step S5, the mixing conditions include: a rotation speed of 20-35 rpm, a temperature of 25-30℃, and a mixing time of 15-30 min.

10. The application of a mussel shell-based biomineralized slow-release conditioner prepared by any one of claims 1-2 or any one of claims 3-8 in crop cultivation.

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