A sand plant growth improver based on a ternary synergistic mechanism and a preparation method and application thereof

Abstract

This invention provides a ternary synergistic mechanism-based sandy soil plant growth improver, its preparation method, and its application, relating to the field of soil improvement technology. The sandy soil plant growth improver of this invention comprises a core, a functional layer, and a protective layer; the core comprises 10-30% compound humic acid base fertilizer, 5-20% mineral-derived potassium humate, 20-40% well-rotted sheep manure, 10-20% zeolite, and 5-15% soybean meal; the functional layer comprises Bacillus subtilis; and the protective layer comprises polyglutamic acid. This ternary synergistic mechanism-based sandy soil plant growth improver utilizes a multi-system synergistic effect of inorganic zeolite, organic humic acid base fertilizer, and active microorganisms to rapidly release nutrients in a short period, while gradually releasing nutrients and organic matter, increasing soil water-holding capacity and fertility, forming water-stable aggregates, improving the ecological environment of sandy soil, promoting plant root growth, and significantly enhancing the growth effect of sandy soil plants.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement technology, specifically relating to a ternary synergistic mechanism-based growth improver for sandy land plants, its preparation method, and its application. Background Technology

[0002] Deserts and sandy areas are characterized by infertile soil, scarce rainfall, and high evaporation rates, leading to significant nutrient and water loss. Desertification control is a major ecological project concerning human survival and sustainable development, holding crucial practical significance for rebuilding ecological barriers and ensuring ecological security. Conventional ecological restoration techniques result in plant survival rates below 40%. Traditional fertilizers and growth promoters used for vegetation restoration in arid deserts generally suffer from core defects such as limited functionality and lack of long-term effectiveness. While traditional inorganic fertilizers (such as sodium-based compound fertilizers) can increase plant survival rates by about 20%, they cannot improve the aggregate structure of sandy soil, resulting in nutrient loss rates as high as 60%. Organic amendments (such as humic acid root promoters) can stimulate root growth, but their water use efficiency is low due to the poor water retention capacity of sandy soils. In the field of microbial fertilizers, single-strain agents (such as Bacillus subtilis) have a colonization rate of less than 10% in the extreme environment of sandy soils, with an activity period of less than 15 days. Although compound microbial preparations can improve stress resistance through multi-strain synergy, the complex fermentation process results in a final cost twice that of conventional fertilizers. More importantly, existing products lack a multi-dimensional synergistic mechanism: water-retaining materials (such as attapulgite clay) have a weak effect on stimulating microbial activity, nutrient fertilizers cannot control water loss, and root-promoting agents have a short degradation half-life in barren sandy soil. Although nano-encapsulated bacterial agents extend the activity period to 45 days, nanomaterials are expensive, severely limiting economic feasibility. Therefore, in the restoration of vegetation on desertified land, there is an urgent need to develop a compound fertilizer that is suitable for large-scale application, low-cost, and multifunctional. Summary of the Invention

[0003] To address the aforementioned technical problems, the primary objective of this invention is to provide a sandy soil plant growth improver based on a ternary synergistic mechanism. This invention utilizes the multiple effects of inorganic zeolite, organic humic acid base fertilizer, and active microorganisms through a ternary synergistic mechanism. This allows for the rapid release of nutrients in a short period, while simultaneously releasing nutrients and organic matter gradually, effectively extending the activity cycle of the microbial agent, continuously increasing soil fertility, exhibiting long-lasting and slow-release properties, and significantly enhancing the growth rate of plant roots and their drought and stress resistance.

[0004] The second objective of this invention is to provide a method for preparing the above-mentioned sandy plant growth improver.

[0005] A third objective of this invention is to provide the application of the above-mentioned sandy soil plant growth improver in improving soil water retention capacity and fertility and / or plant growth.

[0006] The fourth objective of this invention is to provide a method for using the aforementioned sandy plant growth improver.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a sandy land plant growth improver based on a ternary synergistic mechanism, the sandy land plant growth improver comprising a core, a functional layer, and a protective layer; By weight percentage, the raw materials of the core include 10-30% compound humic acid base fertilizer, 5-20% mineral-derived potassium fulvate, 20-40% well-rotted sheep manure, 10-20% zeolite, and 5-15% soybean meal; the raw materials of the functional layer include Bacillus subtilis, and the loading of Bacillus subtilis by the core mass is 1×10⁻⁶. 8 ~5×10 8 CFU / g; the raw material of the protective layer includes polyglutamic acid, and the concentration of the polyglutamic acid solution is 2~5%.

[0008] As one implementation method, the preparation method of the core includes the following steps: mixing compound humic acid base fertilizer, mineral potassium fulvate, decomposed sheep manure, zeolite and soybean meal to obtain a mixture, extruding the mixture into granules, and cooling the granules.

[0009] In one embodiment, the water content of the mixture is 12-15%.

[0010] In one embodiment, the extrusion pressure is 10~15 MPa, the compression ratio is 1:8~12, and the granulation temperature is 35~42℃.

[0011] In one embodiment, the porosity of the particles is 28-35%; the cooling temperature is 20-35°C.

[0012] In one embodiment, the functional layer further includes trehalose at a concentration of 0.05-0.2% and Tween-80 at a concentration of 0.05-0.1%.

[0013] In one embodiment, the thickness of the protective layer is 25~50 µm.

[0014] The present invention also provides a method for preparing the above-mentioned sandy plant growth improver, comprising the following steps: atomizing and spraying a functional layer onto the core, and then spraying a protective layer for coating and curing.

[0015] The present invention also provides the application of the above-mentioned sandy soil plant growth improver in improving soil water retention capacity and fertility and / or plant growth.

[0016] The present invention also provides a method for using the above-mentioned sandy soil plant growth improver, the method comprising applying the sandy soil plant growth improver in holes and / or in trenches; the application amount for hole application is 25-35 g per hole, and the hole application location is 5-15 cm below the root system; the application amount for trench application is 45-60 g per linear meter.

[0017] The advantages of this invention compared to existing technologies are as follows: 1. In this invention, zeolite, acting as a porous carrier, provides continuous nutrient release and water retention capacity. Humic acid and potassium fulvate enhance the soil's pH regulation capacity. Microorganisms, through decomposing organic matter and promoting aggregate formation, comprehensively enhance plant stress resistance and growth rate. Based on a ternary synergistic mechanism, this invention utilizes the multiple effects of inorganic zeolite, organic humic acid base fertilizer, and active microorganisms. It can rapidly release nutrients in a short period while gradually releasing nutrients and organic matter, effectively extending the activity cycle of the microbial agent, continuously increasing soil fertility, exhibiting long-lasting and slow-release properties, and significantly improving plant root growth rate and drought resistance.

[0018] 2. This invention utilizes natural organic materials, resulting in lower production costs and better economic efficiency. By employing waste resource utilization and low-temperature, low-pressure processing techniques, it avoids nutrient loss and microbial activity degradation, reducing energy consumption and material costs during production. Through its efficient process and resource utilization strategy, this invention achieves a low-cost, high-efficiency production model, suitable for large-scale application in arid and desertified areas, and possesses promising market prospects. Attached Figure Description

[0019] Figure 1 The differences in soil pH, electrical conductivity, bulk density, and soil aggregate parameters among different groups; Figure 2 The content of hydrolyzable nitrogen, available phosphorus, and available potassium in soils of different groups; Figure 3 Soil water retention rate for different groups. Detailed Implementation

[0020] This invention provides a sandy land plant growth improver based on a ternary synergistic mechanism, the sandy land plant growth improver comprising a core, a functional layer, and a protective layer; In this invention, by weight percentage, the raw materials of the core include 10-30% compound humic acid base fertilizer, 5-20% mineral-derived potassium fulvate, 20-40% well-rotted sheep manure, 10-20% zeolite, and 5-15% soybean meal; preferably, it includes 15-25% compound humic acid base fertilizer, 10-15% mineral-derived potassium fulvate, 25-35% well-rotted sheep manure, 15-20% zeolite, and 5-10% soybean meal; more preferably, it includes 25% compound humic acid base fertilizer, 15% mineral-derived potassium fulvate, 30% well-rotted sheep manure, 20% zeolite, and 10% soybean meal.

[0021] As an optional implementation, the compound humic acid base fertilizer of the present invention is prepared by conventional methods, dried to a moisture content ≤5%, the drying temperature is 55~65℃, and the drying time is 1.5~3 hours; the obtained compound humic acid base fertilizer has a humic acid content ≥60% and a particle size of 60~100 mesh. The mineral-derived potassium fulvate of the present invention is prepared by conventional methods, the obtained mineral-derived potassium fulvate has a fulvic acid content ≥90%, a K2O content ≥10%, and the pulverized particle size passes through a 100-mesh sieve. The decomposed sheep manure of the present invention is obtained by aerobic fermentation at 50~60℃ followed by pulverization, the obtained decomposed sheep manure has a moisture content ≤15%, and an organic matter content ≥45%. The zeolite of the present invention is obtained by calcining clinoptilolite at 350~450℃ for 1.5~3 hours, the clinoptilolite has a pore size of 0.5~1 mm, and a specific surface area ≥120 m². 2 / g, which can improve the water-retention activity of the zeolite structure. The soybean meal described in this invention has a crude protein content ≥45% and a fat content ≤1%.

[0022] In this invention, well-rotted sheep manure provides a slow-release nitrogen source for sandy soil, while soybean meal provides a carbon source for microorganisms, promoting the degradation of organic matter and improving soil structure. The porous structure of zeolite helps retain moisture, reducing water loss and significantly improving the ecological environment of sandy areas. Mineral-derived potassium humate not only enhances the soil's pH buffering capacity but also provides a rapidly absorbable nutrient source for sandy plants, while its slow-release properties prevent excessive nutrient loss. This invention, by employing slow-release organic materials such as well-rotted sheep manure and soybean meal, combined with the porous structure of zeolite, can gradually release nutrients and organic matter, improve soil aggregate structure, and increase soil water retention capacity and fertility.

[0023] In this invention, the preparation method of the core includes the following steps: mixing the specific proportions of compound humic acid base fertilizer, mineral-derived potassium fulvate, decomposed sheep manure, zeolite, and soybean meal to obtain a mixture; as an optional embodiment, the mixing is carried out in a twin-shaft paddle mixer, the stirring speed is 25~35 rpm, preferably 27 rpm, 30 rpm, or 32 rpm; the stirring time is 15~25 min, preferably 18 min, 20 min, or 23 min. After mixing, the moisture content of the mixture is adjusted to 12-15%, preferably 13% or 14%. Alternatively, the moisture content is adjusted by spraying deionized water, followed by extrusion granulation. Alternatively, the extrusion granulation uses a ring-mode cold extrusion granulator with a die diameter of 2-4 mm, preferably 3 mm. The extrusion pressure is 10-15 MPa, preferably 11 MPa, 12 MPa, 13 MPa, or 14 MPa. The compression ratio is 1:8-12, preferably 1:9, 1:10, or 1:11. The granulation temperature is 35-42℃, preferably 36℃, 37℃, 38℃, 39℃, or 41℃. After granulation, the porosity of the formed particles is 28-35%, preferably 29%, 30%, 31%, 32%, or 33%. The pore size distribution of the particles is 0.5-1 µm, preferably 0.6 µm, 0.7 µm, or 0.8 µm. µm or 0.9 µm. Finally, the particles are cooled; the cooling temperature is 20~35℃. As an optional embodiment, the cooling is performed using a fluidized bed cooler, the inlet air temperature of which is 23~27℃, and the outlet temperature of which is 30~34℃; the cooling time is 8~15 min, preferably 9 min, 10 min, 11 min, 12 min, 13 min, or 14 min.

[0024] In this invention, the raw material for the functional layer includes Bacillus subtilis, which was purchased from Shennong Biotechnology Co., Ltd., and the loading of Bacillus subtilis is 1×10⁻⁶ based on the core mass. 8 ~5×10 8 CFU / g; the raw materials of the functional layer also include 0.05~0.2% trehalose and 0.05~0.1% Tween-80, with trehalose acting as a protective agent to improve the activity of Bacillus subtilis. In this invention, Bacillus subtilis is first activated in a 0.5~1.5% glucose solution to obtain a Bacillus subtilis bacterial suspension. The activation temperature is 25~30℃, and the activation time is 25~35 min. The viable count of the Bacillus subtilis bacterial suspension obtained after activation is ≥1×10⁻⁶. 10The concentration of CFU / mL and the spore count are ≥90%. The *Bacillus subtilis* bacterial solution and a sandy soil growth conditioner are then loaded at a volume-to-mass ratio of 5-15 mL / kg. This invention colonizes *Bacillus subtilis* on the pores and surface of zeolite particles. The penetration depth of the loading is 0.3-1.0 mm, preferably 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, or 0.9 mm. In this invention, *Bacillus subtilis* combined with a porous zeolite carrier can effectively prolong the active period of the bacterial agent and promote its colonization and reproduction in sandy soil. The slow-release mechanism of *Bacillus subtilis* not only helps plant growth but also promotes the cementation of sand particles through extracellular polysaccharide secretion, forming water-stable aggregates, improving soil structure, and enhancing the ability of sandy plants to resist drought, wind, and other environmental stresses.

[0025] In this invention, the raw material of the protective layer includes polyglutamic acid, and the concentration of the polyglutamic acid is 2-5%, preferably 3% or 4%. The thickness of the protective layer is 25-50 µm, preferably 30 µm, 35 µm, 40 µm or 45 µm. This invention protects and solidifies the microbial agent through a secondary coating with polyglutamic acid.

[0026] The present invention also provides a method for preparing the above-mentioned sandy land plant growth improver, comprising the following steps: atomizing and spraying a functional layer onto the core, wherein the functional layer is uniformly sprayed onto the core, and the spraying amount of the functional layer is 10-15 L / ton, preferably 11 L / ton, 12 L / ton, 13 L / ton or 14 L / ton, based on the core mass; the spraying distance is 20-30 cm, preferably 23 cm, 25 cm or 28 cm; the atomization pressure is 0.3-0.5 MPa, preferably 0.4 MPa; the atomized particle size is 40-100 µm, preferably 50 µm, 60 µm, 70 µm, 80 µm or 90 µm. Then, a protective layer is sprayed for coating and curing. As an optional implementation, the spraying is performed using a fluidized bed bottom spray coating machine. The inlet air temperature of the coating machine is 38~45℃, preferably 39℃, 40℃, 41℃, 42℃, 43℃, or 44℃; the inlet air humidity of the coating machine is ≤30%, preferably ≤25%; the atomization pressure of the coating machine is 0.2~0.4 MPa, preferably 0.3 MPa; and the fluidizing air volume of the coating machine is 800~1200 m³ / h. 3 / h, preferably 900 m 3 / h, 1000 m 3 / h or 1100 m 3 / h; the spraying rate is 200~300 mL / min, preferably 250 mL / min. The sandy land plant growth improver prepared by the method of the present invention has a compressive strength ≥15 N, is resistant to breakage during transportation, and has a viable bacteria count ≥1×10 8 It has a CFU / g content, meets the functional sustainability index, and can also inhibit contamination by other microorganisms.

[0027] Based on the present invention, the sandy soil plant growth improver can rapidly release nutrients in a short period of time, while gradually releasing nutrients and organic matter, effectively extending the activity period of the microbial agent, and continuously increasing the fertility of hydrolyzable nitrogen, available phosphorus, and readily available potassium in the soil. This significantly enhances the growth rate of plant roots and their drought resistance and stress tolerance. The present invention also utilizes the aforementioned sandy soil plant growth improver to improve soil water retention capacity and fertility and / or plant growth. In this invention, the sandy soil plant growth improver is suitable for aeolian sandy soils and / or psammophytic plants. As an optional implementation, the soil includes, but is not limited to, semi-fixed and fixed sand dune areas in regions such as the Tarim Basin, Junggar Basin, and Turpan-Hami Basin, with an annual rainfall of <100 mm; the soil bulk density is 1.5~1.7 g / cm³. 3 The pH value is 7.5~8.5, and the field water holding capacity of the soil is 7~9%.

[0028] This invention also provides a method for using the above-mentioned sandy soil plant growth improver, which includes hole application and / or trench application. In this invention, the application amount for hole application is 25-35 g per hole, preferably 30 g; the hole application location is 5-15 cm below the root system, preferably 10 cm, and after application, it is covered with sand 5-7 cm, preferably 5 cm, 6 cm, or 7 cm. In this invention, the application amount for trench application is 45-60 g per linear meter, preferably 50 g or 55 g; the sandy soil plant growth improver and sand are mixed at a mass ratio of 1:2-4 and then backfilled, with the mass ratio preferably being 1:3. The sandy soil plant growth improver of this invention can significantly improve the survival rate and aboveground biomass of sandy soil plants, including sea buckthorn, Haloxylon ammodendron, and Tamarix chinensis. When applying the sandy soil plant growth improver immediately, it should be stored in a cool, dark environment and applied within 24 hours; when applying with a delay, it should be vacuum-packed and refrigerated at 0-4°C.

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the embodiments, but these should not be construed as limiting the scope of protection of this invention.

[0030] Unless otherwise specified, the materials, reagents, etc. used in the following examples are commercially available. Unless otherwise specified, they are generally used under conventional conditions or under conditions recommended by the company.

[0031] Example 1 A sandy land plant growth improver based on a ternary synergistic mechanism, the sandy land plant growth improver being composed of a core, a functional layer, and a protective layer.

[0032] 1. Kernel Preparation S1: 25% compound humic acid base fertilizer, 15% mineral potassium fulvate, 30% well-rotted sheep manure, 20% zeolite, and 10% soybean meal are mixed and stirred in a twin-shaft paddle mixer at a speed of 30 rpm for 20 minutes to obtain a mixture. After mixing, the moisture content of the mixture is adjusted to 12% by spraying deionized water. The compound humic acid base fertilizer is prepared using conventional methods, and dried at 55℃ for 2 hours to achieve a moisture content ≤5%, a humic acid content ≥60%, and a particle size of 60-100 mesh. The mineral-derived potassium fulvate is prepared using conventional methods, resulting in a fulvate content ≥90%, a K₂O content ≥10%, and a particle size passing through a 100-mesh sieve. The decomposed sheep manure is obtained by aerobic fermentation at 55℃ followed by pulverization, resulting in a moisture content ≤15% and an organic matter content ≥45%. The zeolite has a pore size of 0.5-1 mm and a specific surface area ≥120 m². 2 / g of clinoptilolite was activated by calcination at 400℃ for 2 hours. The soybean meal contained ≥45% crude protein and ≤1% fat, and was sterilized by microwave.

[0033] S2: Granulation is carried out using a ring-type cold extrusion granulator with a die diameter of 3 mm. The extrusion pressure is 15 MPa, the compression ratio is 1:10, and the granulation temperature is 38℃. After granulation, the porosity of the resulting particles is 30%, and the pore size distribution is 0.5~1 µm.

[0034] S3: The particles are cooled using a fluidized bed cooler. The inlet air temperature of the cooler is 25°C, and the outlet temperature of the cooler is 32°C. The cooling time is 10 min.

[0035] 2. Functional layer spraying Bacillus subtilis was added to a 1% glucose solution and activated at 25°C for 30 min to obtain a viable count ≥1×10⁻⁶. 10A Bacillus subtilis bacterial suspension with CFU / mL and a spore count ≥90% was prepared. Then, 0.1% trehalose and 0.05% Tween-80 were added to the Bacillus subtilis bacterial suspension as a functional layer. The functional layer was then uniformly sprayed onto the core using a centrifugal atomization system at a pressure of 0.4 MPa and a particle size of 60 µm. Based on the core mass, the coating amount of the functional layer was 12 L / ton, resulting in a Bacillus subtilis loading >1×10⁻⁶. 8 CFU / g, the penetration depth of the load is 0.6 mm.

[0036] 3. Curing of protective coating A fluidized bed bottom spray coating machine was used to coat and solidify the bacteria with 3% polyglutamic acid. The inlet air temperature of the coating machine was controlled at 41℃, the inlet air humidity at 25%, the atomization pressure at 0.3 MPa, and the fluidization air volume at 1000 m³ / h. 3 The spraying rate is 250 mL / min. The coating cures to form a protective layer with a thickness of 30 µm and a water permeability ≥0.5 mL / (cm²). 2 ·h).

[0037] Example 2 A sandy land plant growth improver based on a ternary synergistic mechanism, the sandy land plant growth improver being composed of a core, a functional layer, and a protective layer.

[0038] 1. Kernel Preparation S1: 20% compound humic acid base fertilizer, 10% mineral potassium fulvate, 40% well-rotted sheep manure, 20% zeolite, and 10% soybean meal are mixed and stirred in a twin-shaft paddle mixer at a speed of 25 rpm for 15 minutes to obtain a mixture. After mixing, the moisture content of the mixture is adjusted to 15% by spraying deionized water. The compound humic acid base fertilizer is prepared using conventional methods, dried at 60℃ for 1.5 hours to achieve a moisture content ≤5%, a humic acid content ≥60%, and a particle size of 100 mesh. The mineral-derived potassium fulvate is prepared using conventional methods, resulting in a fulvate content ≥90%, a K₂O content ≥10%, and a particle size passing through a 100-mesh sieve. The decomposed sheep manure is obtained by aerobic fermentation at 50℃ followed by pulverization, resulting in a moisture content ≤15% and an organic matter content ≥45%. The zeolite has a pore size of 0.5~1 mm and a specific surface area ≥120 m². 2 / g of clinoptilolite was activated by calcination at 350℃ for 3 hours. The soybean meal contained ≥45% crude protein and ≤1% fat, and was microwave sterilized.

[0039] S2: Granulation is carried out using a ring-type cold extrusion granulator with a die diameter of 2 mm. The extrusion pressure is 10 MPa, the compression ratio is 1:8, and the granulation temperature is 35℃. After granulation, the porosity of the formed particles is 28%, and the pore size distribution of the particles is 0.5~0.8 µm.

[0040] S3: The particles are cooled using a fluidized bed cooler. The inlet air temperature of the cooler is 27°C, and the outlet temperature of the cooler is 30°C. The cooling time is 8 minutes.

[0041] 2. Functional layer spraying Bacillus subtilis was added to a 0.5% glucose solution and activated at 30°C for 25 min to obtain a viable count ≥1×10⁻⁶. 10 A Bacillus subtilis bacterial suspension with a CFU / mL concentration and a spore count ≥90% was prepared. Then, 0.05% trehalose and 0.05% Tween-80 were added to the Bacillus subtilis bacterial suspension as a functional layer. The functional layer was then uniformly sprayed onto the core using a centrifugal atomization system at a pressure of 0.3 MPa and a particle size of 40 µm. Based on the core mass, the coating amount of the functional layer was 10 L / ton, resulting in a Bacillus subtilis loading >3 × 10⁻⁶. 8 CFU / g, the penetration depth of the load is 0.3 mm.

[0042] 3. Curing of protective coating A fluidized bed bottom spray coating machine was used to coat and solidify the bacteria with 2% polyglutamic acid. The inlet air temperature of the coating machine was controlled at 38℃, the inlet air humidity at 30%, the atomization pressure at 0.2 MPa, and the fluidizing air volume at 800 m³ / h. 3 The spraying rate is 200 mL / min. The coating cures to form a protective layer with a thickness of 25 µm.

[0043] Example 3 A sandy land plant growth improver based on a ternary synergistic mechanism, the sandy land plant growth improver being composed of a core, a functional layer, and a protective layer.

[0044] 1. Kernel Preparation S1: 25% compound humic acid base fertilizer, 15% mineral potassium fulvicate, 30% well-rotted sheep manure, 10% zeolite, and 20% soybean meal are mixed and stirred in a twin-shaft paddle mixer at a speed of 35 rpm for 25 minutes to obtain a mixture. After mixing, the moisture content of the mixture is adjusted to 13% by spraying deionized water. The compound humic acid base fertilizer is prepared using conventional methods, dried at 55℃ for 3 hours to achieve a moisture content ≤5%, a humic acid content ≥60%, and a particle size of 60 mesh. The mineral-derived potassium fulvate is prepared using conventional methods, resulting in a fulvate content ≥90%, a K₂O content ≥10%, and a particle size passing through a 100-mesh sieve. The decomposed sheep manure is obtained by aerobic fermentation at 60℃ followed by pulverization, resulting in a moisture content ≤15% and an organic matter content ≥45%. The zeolite has a pore size of 0.5~1 mm and a specific surface area ≥120 m². 2 / g of clinoptilolite was activated by calcination at 450℃ for 1.5 hours. The soybean meal contained ≥45% crude protein and ≤1% fat, and was microwave sterilized.

[0045] S2: Granulation is carried out using a ring-type cold extrusion granulator with a die diameter of 4 mm. The extrusion pressure is 15 MPa, the compression ratio is 1:12, and the granulation temperature is 42℃. After granulation, the porosity of the resulting particles is 35%, and the pore size distribution is 0.7~1 µm.

[0046] S3: The particles are cooled using a fluidized bed cooler. The inlet air temperature of the cooler is 27°C, and the outlet temperature of the cooler is 34°C. The cooling time is 15 minutes.

[0047] 2. Functional layer spraying Bacillus subtilis was added to a 1.5% glucose solution and activated at 28°C for 35 min to obtain a viable count ≥1×10⁻⁶. 10 A Bacillus subtilis bacterial suspension with CFU / mL and a spore count ≥90% was prepared. Then, 0.2% trehalose and 0.1% Tween-80 were added to the Bacillus subtilis bacterial suspension as a functional layer. The functional layer was then uniformly sprayed onto the core using a centrifugal atomization system at a pressure of 0.5 MPa and a particle size of 80 µm. Based on the core mass, the coating amount of the functional layer was 15 L / ton, resulting in a Bacillus subtilis loading >2 × 10⁻⁶. 8 CFU / g, the penetration depth of the load is 1.0 mm.

[0048] 3. Curing of protective coating A fluidized bed bottom spray coating machine was used to coat and solidify the bacteria with 5% polyglutamic acid. The inlet air temperature of the coating machine was controlled at 45℃, the inlet air humidity at 28%, the atomization pressure at 0.4 MPa, and the fluidizing air volume at 1200 m³ / h. 3 The spraying rate is 300 mL / min. The coating cures to form a protective layer with a thickness of 50 µm.

[0049] Comparative Example 1: Non-functional Layer Spray Coating Group The difference from Example 1 is that no functional layer was applied, but the other preparation processes are the same as in Example 1.

[0050] Comparative Example 2: Low Concentration Microbial Agent Group The difference from Example 1 is that a low concentration of Bacillus subtilis inoculant was added during the functional layer spraying process, controlling the Bacillus subtilis loading to be approximately 1 × 10⁻⁶. 6 CFU / mL, other preparation processes are the same as in Example 1.

[0051] Comparative Example 3: Uncoated Curing Group The difference from Example 1 is that no coating and curing treatment was performed after the functional layer was sprayed; the other preparation processes were the same as in Example 1.

[0052] Experimental Example 1 1. The viable bacteria count, particle compressive strength, moisture content, and slow-release rate of sandy plant growth improvers obtained by the preparation processes of Examples 1-3 and Comparative Examples 1-3 were tested respectively. The test standards and test results are shown in Table 1.

[0053] Table 1. Detection results of plant growth regulators in sandy areas for each group.

[0054] Sand culture method: Dry sand (5% moisture content) at 30℃, add 2mL of sterile water daily, and test the number of viable bacteria remaining in the particles on the 7th day.

[0055] Experimental results showed that all three examples improved the properties of sandy soil. Example 2 showed the highest slow-release rate of the microbial agent, reaching 77.6%. This indicates that increasing the sheep manure content can increase the overall organic matter content in the substrate and effectively improve the slow-release rate of Bacillus subtilis. Increasing the soybean meal content increases the protein content of the substrate and decreases the zeolite content, but it accelerates microbial reproduction, increases the release rate of Bacillus subtilis, decreases the slow-release rate, and shortens the microbial activity period. In the comparison between the examples and comparative examples, the analysis showed that Comparative Example 1, which used a low concentration of microbial agent, had a low microbial population, insufficient for rapid reproduction, thus also reducing the slow-release rate. Comparative Example 2, which did not undergo coating and curing, had lower particle compressive strength, and due to the lack of outer protection, the microorganisms were rapidly released and inactivated, resulting in a final slow-release rate of only 54.9%, which did not meet the qualified standard.

[0056] 2. Soil from potted Haloxylon ammodendron was divided into 7 groups, and sandy soil growth improvers prepared using the processes of Examples 1-3 and Comparative Examples 1-3 were added to each group. A blank control group was used as the control group. After mixing, the soil pH, electrical conductivity, bulk density, and soil aggregates in the control group, the sandy soil growth improvers prepared using the processes of Examples 1-3, and Comparative Examples 1-3 were measured. The test results are as follows: Figure 1 As shown.

[0057] Experimental results show that ( Figure 1 Compared to the control group, the electrical conductivity of Examples 1-3 increased by 131.8%, 110.6%, and 305.9%, respectively; the pH value decreased by 6.7%, 11.6%, and 17.7%, respectively; the soil bulk density decreased by 29.7%, 43.6%, and 37.6%, respectively; and the soil aggregates (>0.25 mm, %) increased by 10.3 times, 11.5 times, and 8.2 times, respectively. All three examples of this invention can effectively improve soil structure, increase soil aggregates, reduce soil bulk density, and increase soil nutrients.

[0058] Compared to Example 1, the electrical conductivity of Comparative Examples 1-3 decreased by 6.7%, 21.3%, and 37.1%, respectively; the bulk density increased by 4.3%, 8.6%, and 22.4%, respectively; the soil aggregates (>0.25 mm, %) decreased by 19.5%, 28.1%, and 43%, respectively; and the soil pH value did not change significantly. Therefore, compared to Example 1, the absence of functional layer spraying, the reduction of microbial agent concentration, or the absence of coating and solidification all resulted in a decrease in soil improvement effect. It is evident that functional layer spraying, high-concentration microbial agents, and coating and solidification technology can all improve soil improvement effects by controlling the long-term release of nutrients and increasing the number of soil microorganisms.

[0059] Experiment 2: Cultivation Experiment of Haloxylon ammodendron Haloxylon ammodendron seedlings: 1-year-old healthy seedlings (15±2 cm tall, with intact root system).

[0060] The unimproved aeolian sand (CK, bulk density 1.65 g / cm³) in the Taklamakan Desert region of the lower reaches of the Keriya River basin in Yutian County was used as the basis for the analysis. 3 As a control group, the area is mostly composed of fixed sand dunes (pH 8.1, field water holding capacity 8%). The region has an arid climate with an annual precipitation of only 40-100 mm and an annual potential evaporation of over 2000 mm.

[0061] In this invention, unmodified aeolian sandy soil was randomly divided into 7 groups: a control group, Examples 1-3, and Comparative Examples 1-3. Each experimental group had 3 replicate plots, with each plot having an area of ​​100 m². 2(10×10 m), the plant spacing was designed to be 2 m, the row spacing to be 3 m, and the planting holes were circular pits with a diameter of 30 cm and a depth of 40 cm. The control group used the original soil for backfilling before planting the Haloxylon ammodendron seedlings; Examples 1-3 and Comparative Examples 1-3 were respectively treated with the corresponding amendments from Examples 1-3 and Comparative Examples 1-3, with an application rate of 2.5 kg. After backfilling with 20 cm of original soil, the amendments were thoroughly mixed with the bottom original soil before planting the Haloxylon ammodendron seedlings, and then covered with the original soil. All groups in this invention used drip irrigation, with an irrigation rate of 2 L / h, a single irrigation volume of 15-20 L, and irrigation once a week for the first month, and twice a month from the second to the sixth month. Thirty days after planting, the survival rate of *Haloxylon ammodendron* was 83% in Group 1, 82% in Group 2, and 85% in Group 3. The survival rate of *Haloxylon ammodendron* in the control group was 54%. The survival rate of *Haloxylon ammodendron* in Comparative Example 1 was 65%, in Comparative Example 2 it was 68%, and in Comparative Example 3 it was 72%. The survival rate of *Haloxylon ammodendron* in Group 1 was 29% higher than that in the control group, in Group 2 it was 28% higher, and in Group 3 it was 31% higher. *Haloxylon ammodendron* in Group 1 was 18% higher than that in Comparative Example 1, 15% higher than that in Comparative Example 2, and 11% higher than that in Comparative Example 3. Six months after planting, the survival rate of *Haloxylon ammodendron* was 72% in Group 1, 71% in Group 2, and 72% in Group 3. The survival rate of *Haloxylon ammodendron* in the control group was 43%. The survival rate of *Haloxylon ammodendron* in Comparative Example 1 was 56%, in Comparative Example 2 it was 57%, and in Comparative Example 3 it was 52%. In Example 1, the survival rate of *Haloxylon ammodendron* was 29% higher than the control group, 16% higher than Comparative Example 1, 15% higher than Comparative Example 2, and 20% higher than Comparative Example 3. Examples 2 and 3 showed increases of 28% and 29% respectively compared to the control group. Simultaneously, the aboveground biomass of *Haloxylon ammodendron* in Example 1 was 89% higher than the control group and 34% higher than Comparative Example 1. The results indicate that all three examples significantly improved the survival rate of *Haloxylon ammodendron* after 30 days and 6 months of planting. Functional layer spraying, adding sufficient *Bacillus subtilis*, and the coating and curing process all improved the survival rate, with more significant effects after 6 months. *Bacillus subtilis* can enhance the growth rate and drought resistance of sandy plants, and the contribution of *Bacillus subtilis* inoculant to the overall improvement in the survival rate of sandy plants accounts for 62.1% of the total improvement effect. p <0.05).

[0062] Experiment 3: Verification of Soil Improvement Effect In Experiment 2, 30 days after planting the Haloxylon ammodendron, soil samples were taken from the planting holes of each group at a depth of 20cm below the surface for measurement. The results are as follows: Microbial activity: qPCR was used to detect the Bacillus subtilis gene copy number. In Example 1 group, the viable count on day 30 was 2 × 10⁻⁶. 7 CFU / g, viable bacterial count in the control group <1×10 3 With a CFU / g count of 0 in the comparative example group, it can be seen that the sandy plant growth improver of this invention effectively extends the activity period of the microbial agent.

[0063] Nutrient content: such as Figure 2 As shown, the hydrolyzable nitrogen content in the soil of Example 1 group was 78.5 mg / kg, the hydrolyzable nitrogen content in the soil of Example 2 group was 176.9 mg / kg, the hydrolyzable nitrogen content in the soil of Example 3 group was 198.1 mg / kg, the hydrolyzable nitrogen content in the soil of Comparative Example 1 group was 63.9 mg / kg, the hydrolyzable nitrogen content in the soil of Comparative Example 2 group was 69.8 mg / kg, the hydrolyzable nitrogen content in the soil of Comparative Example 3 group was 46.2 mg / kg, and the hydrolyzable nitrogen content in the soil of the control group was 21.5 mg / kg. The available potassium content in the soil of Example 1 group was 257.8 mg / kg, the available potassium content in the soil of Example 2 group was 208.5 mg / kg, the available potassium content in the soil of Example 3 group was 279.4 mg / kg, the available potassium content in the soil of Comparative Example 1 group was 224.1 mg / kg, the available potassium content in the soil of Comparative Example 2 group was 237.1 mg / kg, the available potassium content in the soil of Comparative Example 3 group was 211.4 mg / kg, and the available potassium content in the soil of the control group was 21.5 mg / kg. The available phosphorus content in the soil of Example 1 group was 16.8 mg / kg, in Example 2 group it was 27.8 mg / kg, and in Example 3 it was 13.9 mg / kg. The available phosphorus content in the soil of Comparative Example 1 group was 11.3 mg / kg, in Comparative Example 2 it was 12.6 mg / kg, and in Comparative Example 3 it was 6.7 mg / kg. The available phosphorus content in the control group was 0.61 mg / kg. The results indicate that the sandy soil plant growth conditioner can continuously increase the fertility of hydrolyzable nitrogen, available phosphorus, and available potassium in the soil, and can significantly improve the growth rate of plant roots and their drought resistance. Furthermore, comparing Example 1 with Comparative Examples 1-3, it can be found that adding a spray coating, increasing the concentration of microorganisms, and using coating and solidification technology can all increase the content of available nutrients in the soil.

[0064] Water retention: Soil moisture content (-33 kPa) was determined using the ring sampler method. The water retention rate results are as follows: Figure 3As shown, the water retention rate was significantly improved after irrigation. Specifically, the water retention rates of groups 1-3 on day 7 after irrigation increased by 4.1 times, 4.1 times, and 2.4 times, respectively. Compared to Example 1, the soil water retention rates of groups 1-3 on day 7 after irrigation decreased by 8.6%, 43.5%, and 47.8%, respectively. The results indicate that the sandy soil plant growth conditioner of this invention can improve the water retention capacity of sandy soil by approximately 3 times after 7 days. Adding a spray coating, increasing the microbial concentration, and using coating and solidification technology can all improve the soil's water retention capacity.

[0065] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A plant growth improver for sandy areas based on a ternary synergistic mechanism, characterized in that, The sandy land plant growth improver includes a core, a functional layer, and a protective layer; By weight percentage, the raw materials of the core include 10-30% compound humic acid base fertilizer, 5-20% mineral potassium fulvate, 20-40% well-rotted sheep manure, 10-20% zeolite, and 5-15% soybean meal; The raw material for the functional layer includes Bacillus subtilis, and the loading of Bacillus subtilis is 1 × 10⁻⁶ based on the core mass. 8 ~5×10 8 CFU / g; The protective layer is made of polyglutamic acid, and the concentration of the polyglutamic acid solution is 2-5%.

2. The sandy land plant growth improver according to claim 1, characterized in that, The method for preparing the kernel includes the following steps: The compound humic acid base fertilizer, mineral potassium fulvate, decomposed sheep manure, zeolite and soybean meal are mixed to obtain a mixture. The mixture is then extruded and granulated, and the granules are cooled.

3. The sandy land plant growth improver according to claim 2, characterized in that, The water content of the mixture is 12-15%.

4. The sandy land plant growth improver according to claim 2, characterized in that, The extrusion pressure is 10~15MPa, and the compression ratio is 1:8~12; the granulation temperature is 35~42℃.

5. The sandy land plant growth improver according to claim 2, characterized in that, The porosity of the particles is 28-35%; the cooling temperature is 20-35°C.

6. The sandy land plant growth improver according to claim 1, characterized in that, The functional layer also includes trehalose at a concentration of 0.05-0.2% and Tween-80 at a concentration of 0.05-0.1%.

7. The sandy land plant growth improver according to claim 1, characterized in that, The thickness of the protective layer is 25~50 µm.

8. The method for preparing the sandy land plant growth improver according to any one of claims 1 to 7, characterized in that, Includes the following steps: A functional layer is atomized and sprayed onto the matrix core, followed by a protective layer for coating and curing.

9. The application of the sandy soil plant growth improver according to any one of claims 1 to 7 in improving soil water retention capacity and fertility and / or plant growth.

10. The method of using the sandy land plant growth improver according to any one of claims 1 to 7, characterized in that, The application method includes applying the sandy soil plant growth improver in holes and / or trenches; the application amount for hole application is 25-35 g per hole, and the hole application location is 5-15 cm below the root system; the application amount for trench application is 45-60 g per linear meter.

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