Organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner and preparation method thereof

Abstract

The application provides an organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner and a preparation method thereof.The organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner comprises organic materials, microorganism agents and composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads (inorganic materials); the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads are mixed with humic acid and other organic materials and microorganism agents, the slow-release effect of phosphorus and the water retaining effect of soil are further improved, the soil conditioner has high water retaining property and fertilizer slow-release function, the soil conditioner can effectively improve the soil, increase the water retaining property and the availability of phosphorus fertilizer of the soil, improve the enzyme activity of the soil and reduce the loss of water and fertilizer of the soil; the raw materials of the application have wide sources, low cost, safety and harmlessness, the preparation process is simple, the soil conditioner prepared by the application is harmless to the soil environment, has high water retaining property and fertilizer slow-release function, can effectively improve the soil, can be used for enhancing the water retaining property and the physicochemical properties of the soil.

Description

Technical Field

[0001] This invention relates to the field of soil improvement and remediation technology, and in particular to an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner and its preparation method. Background Technology

[0002] With the rapid development of the agricultural economy, soil utilization has gradually increased. However, this high-intensity and high-frequency use has also brought a series of serious problems to the soil. Long-term application of pesticides can lead to soil compaction and decreased fertility; the overuse and abuse of chemical fertilizers can reduce fertilizer efficiency and ultimately cause irreversible damage to soil quality.

[0003] Compared to traditional pesticides and fertilizers, soil conditioners can be formulated with raw materials to address specific soil problems, providing targeted solutions to current significant soil issues. They offer three main benefits to the tested soil: water retention, fertilizer retention, and aeration. Through the combined application of agricultural water-retaining agents and organic matter, they effectively regulate the soil environment, thereby resolving problems such as soil compaction, poor water retention, and decreased fertilizer efficiency. Furthermore, the raw materials used to prepare soil conditioners are safe, harmless, and environmentally friendly, generally not causing secondary pollution.

[0004] For soils that are extremely water-scarce and have poor water and fertilizer retention, a soil conditioner with both high water and fertilizer retention capabilities is needed. This places high demands on the types of water-retaining agents used in its raw materials. Generally, water-retaining agents are mainly superabsorbent polymers derived from physically or chemically cross-linked polymers. Due to their porous structure and abundant hydrophilic groups, they can absorb and retain large amounts of water for soil use. However, currently, most superabsorbent polymers used are mainly derived from petrochemical products, which are not only expensive but also have poor degradation properties when applied to soil, easily causing environmental hazards, thus limiting their application.

[0005] Existing technology discloses an organic-inorganic composite superabsorbent and water-retaining material and its preparation method. This invention mixes inorganic clay with an alkali cellulose solution, and then mixes it with a polymer crosslinking agent to prepare a superabsorbent and water-retaining material. The combination of inorganic clay and polymer improves the structural strength and physical properties of the material while reducing the self-crosslinking density of the polymer, thereby increasing the material's water absorption and swelling properties and effectively regulating soil water retention. However, the superabsorbent and water-retaining material provided by this invention uses a large amount of sodium hydroxide in its preparation process, making the material overall alkaline. This may lead to soil alkalization during use, negatively impacting the soil's acid-base environment.

[0006] Existing technology discloses an aerogel soil water-retaining and fertilizer-retaining agent and its preparation process. This invention prepares the water-retaining and fertilizer-retaining material by mixing and fermenting aerogel, microbial inoculants, inorganic fertilizer, and organic fertilizer. The material of this invention integrates organic, inorganic, and biological elements, and achieves the best effect through a series of treatments. However, this invention has too many raw materials, a complex preparation process, uses low-temperature freeze-drying in the preparation of intermediates, and the final product is also completed through fermentation. The harsh preparation conditions limit the application of this material.

[0007] Currently, there are numerous studies on compound soil conditioners, but most of them involve complicated preparation processes, demanding conditions, and produce only one effect, failing to simultaneously achieve water retention, fertilizer retention, and conditioning effects. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner and its preparation method. The organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner of this invention has high water absorption and retention properties and slow-release fertilizer function, which can effectively improve the soil, increase soil water retention and phosphate fertilizer effectiveness, enhance soil enzyme activity, and reduce soil moisture and fertility loss.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner, comprising organic materials, microbial agents, and compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads;

[0011] The organic materials include humic acid and lignin;

[0012] The microbial agents include microalgae and yeast.

[0013] Preferably, the preparation method of the composite phosphate fertilizer slow-release carboxylated modified hydrogel microspheres includes the following steps:

[0014] The compound phosphate fertilizer was dispersed in an aqueous solution of sodium alginate to obtain a mixed suspension;

[0015] The mixed suspension was injected into a calcium ion-containing solution and filtered to obtain compound phosphate fertilizer slow-release microbeads.

[0016] The compound phosphate fertilizer slow-release microbeads were immersed in a chloroacetic acid solution, the pH was adjusted to 7-9, stirred, and filtered to obtain compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads.

[0017] Preferably, the composition includes the following components by weight: 10-20 parts organic material, 0.2-1 part microbial agent, and 30-40 parts compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres.

[0018] Preferably, the mass ratio of humic acid to lignin is (1-2):1;

[0019] The mass ratio of microalgae to yeast is (1-2):(1-2).

[0020] Preferably, the compound phosphate fertilizer is dispersed in an aqueous solution of sodium alginate and stirred at 16–25°C and 550–650 rpm for 1–2 hours to obtain a mixed suspension;

[0021] The mixed suspension was injected into a calcium ion-containing solution using a syringe pump with a needle diameter of 1–1.5 mm. The mixture was stirred at 200–250 rpm and 16–25°C for 45–60 min, allowed to stand for 2–3 h, filtered, and washed to obtain compound phosphate fertilizer slow-release microbeads.

[0022] The compound phosphate fertilizer slow-release microbeads were immersed in chloroacetic acid solution, the pH was adjusted to 7-9, and the mixture was stirred at 60-200 rpm and 16-25℃ for 8-11 hours. The mixture was then filtered, washed until neutral, and dried to obtain compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads.

[0023] Preferably, the compound phosphate fertilizer includes superphosphate, triple superphosphate, and potassium dihydrogen phosphate;

[0024] The mass ratio of potassium dihydrogen phosphate, superphosphate, and triple superphosphate is (1-2):(1-3):(0-2);

[0025] The calcium ion-containing solution includes at least one of CaCl2 solution, CaSO4 solution, Ca(NO)3 solution, and phosphogypsum leachate.

[0026] Preferably, the mass concentration of the sodium alginate aqueous solution is 1-2%;

[0027] The mass concentration of the calcium ion-containing solution is 2-4%;

[0028] The concentration of the chloroacetic acid solution is 0.2–0.5 mol / L.

[0029] Preferably, the mass-to-volume ratio of the compound phosphate fertilizer, sodium alginate aqueous solution, and calcium ion-containing solution is (3-4) g:(5-7) g:(100-250) mL.

[0030] Preferably, the compound phosphate fertilizer slow-release microbeads are immersed in a chloroacetic acid solution, and the pH is adjusted to 7-9 using a 0.02-0.1 mol / L sodium hydroxide aqueous solution. After stirring and filtration, the compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads are obtained.

[0031] Secondly, the present invention also provides a method for preparing the aforementioned organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner, comprising the following steps:

[0032] The organic materials and microbial agents are mixed evenly to obtain a mixture;

[0033] By mixing compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads with the mixture, an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner is obtained.

[0034] The organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner and its preparation method of the present invention have the following advantages compared with the prior art:

[0035] 1. The organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner of the present invention includes organic materials, microbial agents, and compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres (inorganic materials); the compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres are mixed with organic materials such as humic acid and microbial agents to further improve the slow-release effect of phosphorus and the water absorption and retention effect of soil, and have high water absorption and retention and fertilizer slow-release function, which can effectively improve soil, increase soil water retention and phosphate fertilizer effectiveness, enhance soil enzyme activity, and reduce soil moisture and fertilizer loss;

[0036] 2. The compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres of the present invention are obtained by mixing compound phosphate fertilizer with sodium alginate aqueous solution to obtain a mixed suspension; the mixed suspension is injected into a calcium ion-containing solution, and sodium alginate aqueous solution crosslinks with calcium ions to form sodium alginate gel. By means of this gelation process, the compound phosphate fertilizer is loaded to construct a gel microsphere structure; by utilizing the structural characteristics of gel microspheres, the release rate of phosphate fertilizer in soil can be effectively extended; furthermore, the compound phosphate fertilizer slow-release microspheres are modified by carboxylation with chloroacetic acid, so that more carboxyl groups are loaded on the gel microspheres, improving the water absorption units in the gel microspheres and further enhancing the water absorption and retention performance of the microspheres;

[0037] 3. This invention is based on three purposes: water retention, fertilizer retention, and conditioning. Organic materials such as humic acid and lignin can not only regulate the soil's acid-base environment and nutrient activity, promote the formation of soil aggregates, and increase porosity, but also provide substrates for soil and microbial enzyme activity. Microbial agents such as yeast and microalgae secrete organic acids (such as citric acid and oxalic acid) which can dissolve fixed phosphates in the soil, and can secrete various enzymes during the mixing process with organic materials, accelerating the transformation of organic matter. Both organic materials and microbial agents contain a large number of hydrophilic functional groups, which can improve the overall water retention, and can also promote the activation of nutrients during the contact with gel microbeads.

[0038] 4. The organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner of this invention improves the physicochemical structure and biological activity of soil through the synergistic effect of organic materials, microbial agents, and inorganic materials (i.e., compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres): the compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres absorb water and swell to form physical support, reducing soil bulk density and constructing a pore network; organic materials are decomposed by microorganisms to generate humus, which cements soil particles through functional groups to form stable aggregates; polysaccharides and gases produced by microbial metabolism further induce the formation of micropores; at the same time, the microbial agents and slow-release phosphate fertilizer in the conditioner provide carbon and phosphorus sources for soil microorganisms, activate phosphatase gene expression, significantly enhance alkaline phosphatase activity, and accelerate soil organic phosphorus mineralization. This synergistic effect significantly reduces soil bulk density, increases total porosity, and enhances alkaline phosphatase activity, achieving multiple improvement effects of "loose structure-pore optimization-enzyme-enhanced efficiency";

[0039] 5. The preparation method of the organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner of the present invention has a wide range of raw material sources, low cost, safety and harmlessness, and simple preparation process. The prepared soil conditioner is harmless to the soil environment and has high water absorption and water retention and fertilizer slow release function. It can effectively improve the soil, increase soil water retention and phosphate fertilizer effectiveness, reduce soil moisture and fertilizer loss, and can be used to enhance soil water retention and soil physicochemical properties. Detailed Implementation

[0040] To facilitate understanding of the present invention, a more comprehensive description of the invention will be provided below in conjunction with specific embodiments. Preferred embodiments of the invention are given in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0041] The order in which the embodiments are described below is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0042] This invention provides an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner, comprising organic materials, microbial agents, and compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads;

[0043] Organic materials include humic acid and lignin;

[0044] Microbial agents include microalgae and yeast.

[0045] The organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner of the present invention includes organic materials, microbial agents, and compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres (inorganic materials); the compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres are mixed with organic materials such as humic acid and microbial agents to further improve the slow-release effect of phosphorus and the water absorption and retention effect of soil, and have high water absorption and retention and fertilizer slow-release function, which can effectively improve soil, increase soil water retention and phosphate fertilizer effectiveness, enhance soil enzyme activity, and reduce soil moisture and fertilizer loss.

[0046] The organic materials in this invention include humic acid and lignin. Humic acid is an organic substance formed from the decomposition and transformation of plant and animal remains by microorganisms. Lignin is the main component of lignocellulose biomass, synthesized from the cell walls of higher plants, and has good biocompatibility. Both organic materials contain abundant functional groups, which can promote the formation of soil aggregates, improve soil permeability and water retention, promote nutrient absorption, and stabilize soil pH. Mixing them with compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres can also reduce the fixation of fertilizer elements in the soil through complexation and other mechanisms, thereby achieving the purpose of slow-release fertilizer effects.

[0047] The microbial inoculant in this invention includes microalgae and yeast. Microalgae are a class of small, simple, low-level autotrophic organisms containing nutrients and bioactive substances such as nitrogen, phosphorus, and trace elements that can promote plant and animal growth and improve the quality of agricultural products. Due to the microbial cell characteristics of microalgae, their application in soil can effectively absorb and release nutrients such as nitrogen, phosphorus, and potassium. They can also solubilize fixed phosphorus in the soil, promoting phosphorus activation and thus improving soil structure. For certain types of microalgae, such as cyanobacteria, they can also fix nitrogen, all of which contribute to improving soil fertility. Yeast is an aquatic, single-celled eukaryotic organism with numerous hydrophilic functional groups, including amide, phosphate, amine, carboxyl, and hydroxyl groups, providing a large number of hydrophilic groups and enhancing the water absorption and retention capacity of the material. The microbial inoculant can increase soil microbial activity while simultaneously promoting the release and transformation of nutrients in the soil environment through its numerous functional groups, further improving soil structure.

[0048] In some embodiments, the preparation method of compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres includes the following steps:

[0049] The compound phosphate fertilizer was dispersed in an aqueous solution of sodium alginate to obtain a mixed suspension;

[0050] The mixed suspension was injected into a calcium ion-containing solution and filtered to obtain compound phosphate fertilizer slow-release microbeads.

[0051] The compound phosphate fertilizer slow-release microbeads were immersed in a chloroacetic acid solution, the pH was adjusted to 7-9, stirred, and filtered to obtain compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads.

[0052] The present invention discloses a method for preparing compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres. This involves obtaining a mixed suspension by mixing compound phosphate fertilizer with an aqueous solution of sodium alginate. The mixed suspension is then injected into a calcium ion-containing solution. Upon crosslinking with the calcium ions, the sodium alginate aqueous solution forms a sodium alginate gel. This gelation process loads the compound phosphate fertilizer, constructing a gel microsphere structure. By utilizing the structural characteristics of the gel microspheres, the release rate of phosphate fertilizer in the soil can be effectively reduced, extending the duration of action. Furthermore, the mixing of compound phosphate fertilizer and sodium alginate effectively enhances the mechanical strength and structure of the sodium alginate gel microspheres. Stability; furthermore, the composite phosphate fertilizer slow-release microspheres are modified by carboxylation with chloroacetic acid, so that more carboxyl groups are loaded on the gel microspheres, which improves the water absorption units in the gel microspheres and further enhances the water absorption and retention performance of the microspheres; the composite phosphate fertilizer slow-release carboxylated modified hydrogel microspheres prepared by this invention have good pH response. The carboxylation modification loads more carboxyl groups on the gel microsphere structure. The change of pH is accompanied by the protonation and deprotonation process of the carboxyl groups, which affects the stability of chemical bonds and the stability of the overall structure, and further affects the water absorption and release rate and the release rate of the contents of the material.

[0053] This invention is based on three purposes: water retention, fertilizer retention, and conditioning. Organic materials such as humic acid and lignin can not only regulate the soil's acid-base environment and nutrient activity, promote soil aggregate formation, and increase porosity, but also provide substrates for soil and microbial enzyme activity. Microbial agents such as yeast and microalgae secrete organic acids (such as citric acid and oxalic acid) which can dissolve fixed phosphates in the soil, and can secrete various enzymes during the mixing process with organic materials, accelerating the transformation of organic matter. Both organic materials and microbial agents contain a large number of hydrophilic functional groups, which can improve the overall water retention, and can also promote the activation of nutrients during the contact with gel microbeads.

[0054] This invention relates to an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner. Through the synergistic effect of organic materials, microbial agents, and inorganic materials (i.e., compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres), it improves the physicochemical structure and biological activity of soil. The compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres absorb water and swell, forming physical support, reducing soil bulk density, and constructing a porous network. Organic materials are decomposed by microorganisms to generate humus, which cements soil particles through functional groups, forming stable aggregates. Polysaccharides and gases produced by microbial metabolism further induce micropore formation. Simultaneously, the microbial agents and slow-release phosphate fertilizer in the conditioner provide carbon and phosphorus sources for soil microorganisms, activating phosphatase gene expression, significantly increasing alkaline phosphatase activity, and accelerating soil organic phosphorus mineralization. This synergistic effect significantly reduces soil bulk density, increases total porosity, and enhances alkaline phosphatase activity, achieving multiple improvement effects of "loose structure, optimized pores, and enhanced enzyme activity."

[0055] In some embodiments, the product comprises the following components in parts by weight: 10-20 parts of organic material, 0.2-1 parts of microbial agent, and 30-40 parts of compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres.

[0056] In some embodiments, the mass ratio of humic acid to lignin is (1-2):1;

[0057] The mass ratio of microalgae to yeast is (1-2):(1-2).

[0058] In some embodiments, the compound phosphate fertilizer is dispersed in an aqueous sodium alginate solution and stirred at 16–25°C and 550–650 rpm for 1–2 hours to obtain a mixed suspension.

[0059] The mixed suspension was injected into a calcium ion-containing solution using a syringe pump with a needle diameter of 1–1.5 mm. The mixture was stirred at 200–250 rpm and 16–25°C for 45–60 min, allowed to stand for 2–3 h, filtered, and washed to obtain compound phosphate fertilizer slow-release microbeads.

[0060] The compound phosphate fertilizer slow-release microbeads were immersed in chloroacetic acid solution, the pH was adjusted to 7-9, and the mixture was stirred at 60-200 rpm and 16-25℃ for 8-11 hours. The mixture was then filtered, washed until neutral, and dried to obtain compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads.

[0061] In some embodiments, the compound phosphate fertilizer includes superphosphate, triple superphosphate, and potassium dihydrogen phosphate.

[0062] The mass ratio of potassium dihydrogen phosphate, superphosphate, and triple superphosphate is (1-2):(1-3):(0-2);

[0063] In some embodiments, the calcium ion-containing solution includes at least one of CaCl2 solution, CaSO4 solution, Ca(NO)3 solution, and phosphogypsum leachate.

[0064] Specifically, the preparation method of phosphogypsum leachate is as follows: phosphogypsum is crushed and soaked in water, then filtered to obtain phosphogypsum leachate; wherein, the calcium ion mass concentration in the phosphogypsum leachate is 2-4%;

[0065] The chemical composition of phosphogypsum is shown in Table 1 below.

[0066] Table 1 - Chemical Composition of Phosphogypsum

[0067]

[0068] In Table 1, Loss represents weight loss on ignition.

[0069] In some embodiments, the mass concentration of the sodium alginate aqueous solution is 1-2%;

[0070] The mass concentration of the calcium ion-containing solution is 2-4%;

[0071] The concentration of the chloroacetic acid solution is 0.2–0.5 mol / L.

[0072] In some embodiments, the mass-to-volume ratio of compound phosphate fertilizer, sodium alginate aqueous solution, and calcium ion-containing solution is (3-4) g:(5-7) g:(100-250) mL.

[0073] In some embodiments, the compound phosphate fertilizer slow-release microbeads are immersed in a chloroacetic acid solution, and the pH is adjusted to 7-9 using a 0.02-0.1 mol / L sodium hydroxide aqueous solution. After stirring and filtration, the compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads are obtained.

[0074] Specifically, there is no limit to the volume of the chloroacetic acid solution, as long as it completely submerges the compound phosphate fertilizer slow-release microbeads.

[0075] In some embodiments, the microalgae are selected from at least one of Chlorella zosteri, Chlorella proteoglycana, Scenedesmus, Euglena, and Haematococcus pluvialis.

[0076] Based on the same inventive concept, the present invention also provides a method for preparing the above-mentioned organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner, comprising the following steps:

[0077] The organic materials and microbial agents are mixed evenly to obtain a mixture;

[0078] By mixing compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads with the mixture, an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner is obtained.

[0079] The method for preparing the organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner of the present invention has a wide range of raw material sources, low cost, safety and harmlessness, and simple preparation process. The prepared soil conditioner is harmless to the soil environment and has high water absorption and water retention and fertilizer slow-release function. It can effectively improve the soil, increase soil water retention and phosphate fertilizer effectiveness, reduce soil moisture and fertility loss, and can be used to enhance soil water retention and soil physicochemical properties.

[0080] The following specific embodiments further illustrate the organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner and its preparation method of the present invention. This section further illustrates the content of the present invention in conjunction with specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0081] In the following examples and comparative examples, sodium alginate was purchased from Maclean's Reagent, specifically sodium alginate S817374, CAS number: 9005-38-3;

[0082] The superphosphate was purchased from Maclean's reagent, specifically C822236 superphosphate monohydrate, CAS number: 10031-30-8;

[0083] Humic acid was purchased from Maclean's reagents, specifically H742187 humic acid, CAS number: 1415-93-6;

[0084] The lignin was purchased from Maclean's reagent, specifically L969910 lignin, CAS number: 23363-35-1;

[0085] The yeast was purchased from Maclean's reagents, specifically Y750241 yeast powder;

[0086] The microalgae is Chlorella proteoglycans, purchased from Shanghai Zhongfeng Biotechnology Co., Ltd.

[0087] Example 1

[0088] This embodiment provides an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner, comprising 15 kg of organic materials, 0.5 kg of microbial inoculants, and 35 kg of compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads;

[0089] The 15kg organic material is composed of a mixture of 10kg humic acid and 5kg lignin.

[0090] 0.5 kg of microbial inoculant is a mixture of 0.2 kg of microalgae and 0.3 kg of yeast;

[0091] The preparation method of carboxylated modified hydrogel microspheres for slow-release compound phosphate fertilizer includes the following steps:

[0092] S1. Disperse 2g of potassium dihydrogen phosphate and 1g of superphosphate in 5g of 1wt% sodium alginate aqueous solution using ultrasonication, and then stir at 25℃ and 550rpm for 2h to obtain a mixed suspension for later use.

[0093] S2. The mixed suspension in S1 was injected into 250 mL of 2 wt% CaCl2 aqueous solution using a syringe pump with a needle diameter of 1 mm. The mixture was stirred at 200 rpm and 25 °C for 60 min, allowed to stand for 3 h, filtered, and the filtered spheres were rinsed 3 times with deionized water to obtain the compound phosphate fertilizer slow-release microspheres.

[0094] S3. Soak the compound phosphate fertilizer slow-release microbeads from S2 in a 0.4 mol / L chloroacetic acid aqueous solution (500 mL of chloroacetic acid solution completely submerges the compound phosphate fertilizer slow-release microbeads), adjust the pH to 8 with a 0.02 mol / L sodium hydroxide aqueous solution, stir at 150 rpm and 25℃ for 10 h, filter, rinse the filtered spheres with deionized water until neutral, and dry at room temperature (25℃) to obtain compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads.

[0095] The preparation method of the above-mentioned organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner includes:

[0096] Mix 15 kg of organic material and 0.5 kg of microbial inoculant to obtain a mixture;

[0097] 35 kg of slow-release carboxylated modified hydrogel microspheres of compound phosphate fertilizer were mixed with the mixture to obtain an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner.

[0098] Example 2

[0099] This embodiment provides an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner, comprising 10 kg of organic materials, 0.6 kg of microbial inoculants, and 40 kg of compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads;

[0100] The 10kg organic material consists of a mixture of 5kg humic acid and 5kg lignin.

[0101] 0.6 kg of microbial inoculant is a mixture of 0.3 kg of microalgae and 0.3 kg of yeast;

[0102] The preparation method of carboxylated modified hydrogel microspheres for slow-release compound phosphate fertilizer includes the following steps:

[0103] S1. Disperse 3g of potassium dihydrogen phosphate and 1g of superphosphate in 6g of 2wt% sodium alginate aqueous solution using ultrasonication, and then stir at 25℃ and 650rpm for 1.5h to obtain a mixed suspension for later use.

[0104] S2. The mixed suspension in S1 was injected into 250 mL of 3 wt% CaCl2 aqueous solution using a syringe pump with a needle diameter of 1.5 mm. The mixture was stirred at 200 rpm and 25 °C for 60 min, allowed to stand for 3 h, filtered, and the filtered spheres were rinsed 3 times with deionized water to obtain the compound phosphate fertilizer slow-release microspheres.

[0105] S3. Soak the compound phosphate fertilizer slow-release microbeads from S2 in a 0.3 mol / L chloroacetic acid aqueous solution (500 mL of chloroacetic acid solution completely submerges the compound phosphate fertilizer slow-release microbeads), adjust the pH to 8 with a 0.05 mol / L sodium hydroxide aqueous solution, stir at 200 rpm and 25℃ for 9 h, filter, rinse the filtered spheres with deionized water until neutral, and dry at room temperature (25℃) to obtain compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads.

[0106] The preparation method of the above-mentioned organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner includes:

[0107] Mix 10 kg of organic material and 0.6 kg of microbial inoculant to obtain a mixture;

[0108] 40 kg of compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres were mixed with the mixture to obtain an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner.

[0109] Example 3

[0110] This embodiment provides an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner, comprising 15 kg of organic materials, 1 kg of microbial inoculant, and 30 kg of compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads.

[0111] The 15kg organic material is composed of a mixture of 10kg humic acid and 5kg lignin.

[0112] 1 kg of microbial inoculant is made by mixing 0.5 kg of microalgae and 0.5 kg of yeast;

[0113] The preparation method of carboxylated modified hydrogel microspheres for slow-release compound phosphate fertilizer includes the following steps:

[0114] S1. Disperse 2g of potassium dihydrogen phosphate and 2g of superphosphate in 7g of 2wt% sodium alginate aqueous solution using ultrasonication, and then stir at 25℃ and 650rpm for 1.5h to obtain a mixed suspension for later use.

[0115] S2. The mixed suspension in S1 was injected into 250 mL of 4 wt% CaCl2 aqueous solution using a syringe pump with a needle diameter of 1.5 mm. The mixture was stirred at 200 rpm and 25 °C for 45 min, allowed to stand for 3 h, filtered, and the filtered spheres were rinsed 3 times with deionized water to obtain the compound phosphate fertilizer slow-release microbeads.

[0116] S3. Soak the compound phosphate fertilizer slow-release microbeads from S2 in a 0.5 mol / L chloroacetic acid aqueous solution (500 mL of chloroacetic acid solution completely submerges the compound phosphate fertilizer slow-release microbeads), adjust the pH to 9 with a 0.08 mol / L sodium hydroxide aqueous solution, stir at 180 rpm and 25℃ for 11 h, filter, rinse the filtered spheres with deionized water until neutral, and dry at room temperature (25℃) to obtain compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads.

[0117] The preparation method of the above-mentioned organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner includes:

[0118] Mix 15 kg of organic material and 1 kg of microbial inoculant to obtain a mixture;

[0119] 30 kg of slow-release carboxylated modified hydrogel microspheres of compound phosphate fertilizer were mixed with the mixture to obtain an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner.

[0120] Example 4

[0121] This embodiment provides an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner, which is the same as in embodiment 1, except that in the preparation of the composite phosphate fertilizer slow-release carboxylation modified hydrogel microspheres, 250 mL of 3 wt% phosphogypsum leachate is used in step S2.

[0122] Specifically, the organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner includes 15kg of organic materials, 0.5kg of microbial inoculants, and 35kg of compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads.

[0123] The 15kg organic material is composed of a mixture of 10kg humic acid and 5kg lignin.

[0124] 0.5 kg of microbial inoculant is a mixture of 0.2 kg of microalgae and 0.3 kg of yeast;

[0125] The preparation method of carboxylated modified hydrogel microspheres for slow-release compound phosphate fertilizer includes the following steps:

[0126] S1. Disperse 2g of potassium dihydrogen phosphate and 1g of superphosphate in 5g of 1wt% sodium alginate aqueous solution using ultrasonication, and then stir at 25℃ and 550rpm for 2h to obtain a mixed suspension for later use.

[0127] S2. The mixed suspension in S1 was injected into 250 mL of phosphogypsum extract containing 3 wt% calcium ions (the preparation of phosphogypsum extract is as described above) using a syringe pump with a needle diameter of 1 mm. The mixture was stirred at 200 rpm and 25 °C for 60 min, allowed to stand for 3 h, filtered, and the filtered spheres were rinsed 3 times with deionized water to obtain composite phosphate fertilizer slow-release microspheres.

[0128] S3. Soak the compound phosphate fertilizer slow-release microbeads from S2 in a 0.4 mol / L chloroacetic acid aqueous solution (500 mL of chloroacetic acid solution completely submerges the compound phosphate fertilizer slow-release microbeads), adjust the pH to 8 with a 0.02 mol / L sodium hydroxide aqueous solution, stir at 150 rpm and 25℃ for 10 h, filter, rinse the filtered spheres with deionized water until neutral, and dry at room temperature (25℃) to obtain compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads.

[0129] The preparation method of the above-mentioned organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner includes:

[0130] Mix 15 kg of organic material and 0.5 kg of microbial inoculant to obtain a mixture;

[0131] 35 kg of slow-release carboxylated modified hydrogel microspheres of compound phosphate fertilizer were mixed with the mixture to obtain an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner.

[0132] Comparative Example 1

[0133] This comparative example provides a soil conditioner, which is the same as Example 1, except that no organic materials are added; specifically, the soil conditioner includes 0.5 kg of microbial inoculant and 35 kg of compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads.

[0134] The 0.5 kg microbial inoculant is composed of 0.2 kg microalgae and 0.3 kg yeast.

[0135] The preparation method of carboxylated modified hydrogel microspheres for slow-release compound phosphate fertilizer includes the following steps:

[0136] S1. Disperse 2g of potassium dihydrogen phosphate and 1g of superphosphate in 5g of 1wt% sodium alginate aqueous solution using ultrasonication, and then stir at 25℃ and 550rpm for 2h to obtain a mixed suspension for later use.

[0137] S2. The mixed suspension in S1 was injected into 250 mL of 2 wt% CaCl2 aqueous solution using a syringe pump with a needle diameter of 1 mm. The mixture was stirred at 200 rpm and 25 °C for 60 min, allowed to stand for 3 h, filtered, and the filtered spheres were rinsed 3 times with deionized water to obtain the compound phosphate fertilizer slow-release microspheres.

[0138] S3. Soak the compound phosphate fertilizer slow-release microbeads from S2 in a 0.4 mol / L chloroacetic acid aqueous solution (500 mL of chloroacetic acid solution completely submerges the compound phosphate fertilizer slow-release microbeads), adjust the pH to 8 with a 0.02 mol / L sodium hydroxide aqueous solution, stir at 150 rpm and 25℃ for 10 h, filter, rinse the filtered spheres with deionized water until neutral, and dry at room temperature (25℃) to obtain compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads.

[0139] The preparation method of the above-mentioned soil conditioner includes:

[0140] 0.5 kg of microbial inoculant was mixed with 35 kg of slow-release carboxylated modified hydrogel microspheres of compound phosphate fertilizer to obtain a soil conditioner.

[0141] Comparative Example 2

[0142] This comparative example provides a soil conditioner, which is the same as Example 1, except that no microbial inoculant is added; specifically, the soil conditioner includes 15 kg of organic material and 35 kg of compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres.

[0143] The 15kg organic material is composed of a mixture of 10kg humic acid and 5kg lignin.

[0144] The preparation method of carboxylated modified hydrogel microspheres for slow-release compound phosphate fertilizer includes the following steps:

[0145] S1. Disperse 2g of potassium dihydrogen phosphate and 1g of superphosphate in 5g of 1wt% sodium alginate aqueous solution using ultrasonication, and then stir at 25℃ and 550rpm for 2h to obtain a mixed suspension for later use.

[0146] S2. The mixed suspension in S1 was injected into 250 mL of 2 wt% CaCl2 aqueous solution using a syringe pump with a needle diameter of 1 mm. The mixture was stirred at 200 rpm and 25 °C for 60 min, allowed to stand for 3 h, filtered, and the filtered spheres were rinsed 3 times with deionized water to obtain the compound phosphate fertilizer slow-release microspheres.

[0147] S3. Soak the compound phosphate fertilizer slow-release microbeads from S2 in a 0.4 mol / L chloroacetic acid aqueous solution (500 mL of chloroacetic acid solution completely submerges the compound phosphate fertilizer slow-release microbeads), adjust the pH to 8 with a 0.02 mol / L sodium hydroxide aqueous solution, stir at 150 rpm and 25℃ for 10 h, filter, rinse the filtered spheres with deionized water until neutral, and dry at room temperature (25℃) to obtain compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads.

[0148] The preparation method of the above-mentioned soil conditioner includes:

[0149] 35 kg of slow-release carboxylated modified hydrogel microspheres of compound phosphate fertilizer were mixed with 15 kg of organic material to obtain an organic-inorganic-microbial composite soil conditioner for water and fertilizer retention.

[0150] Comparative Example 3

[0151] This comparative example provides a soil conditioner, which is the same as Example 1, except that the compound phosphate fertilizer slow-release hydrogel microspheres have not undergone carboxylation modification; specifically, the soil conditioner includes 15 kg of organic material, 0.5 kg of microbial inoculant, and 35 kg of compound phosphate fertilizer slow-release hydrogel microspheres.

[0152] The 15kg organic material is composed of a mixture of 10kg humic acid and 5kg lignin.

[0153] 0.5 kg of microbial inoculant is a mixture of 0.2 kg of microalgae and 0.3 kg of yeast;

[0154] The preparation method of compound phosphate fertilizer slow-release hydrogel microspheres includes the following steps:

[0155] S1. Disperse 2g of potassium dihydrogen phosphate and 1g of superphosphate in 5g of 1wt% sodium alginate aqueous solution using ultrasonication, and then stir at 25℃ and 550rpm for 2h to obtain a mixed suspension for later use.

[0156] S2. The mixed suspension in S1 was injected into 250 mL of 2 wt% CaCl2 aqueous solution using a syringe pump with a needle diameter of 1 mm. The mixture was stirred at 200 rpm and 25 °C for 60 min, allowed to stand for 3 h, filtered, and the filtered spheres were rinsed 3 times with deionized water to obtain the compound phosphate fertilizer slow-release microspheres.

[0157] S3. Rinse the compound phosphate fertilizer slow-release microbeads in S3 with deionized water until neutral, and dry at room temperature to obtain compound phosphate fertilizer slow-release hydrogel microbeads.

[0158] The preparation method of the above-mentioned soil conditioner includes:

[0159] Mix 15 kg of organic material and 0.5 kg of microbial inoculant to obtain a mixture;

[0160] 35 kg of compound phosphate fertilizer slow-release hydrogel microspheres were mixed with the mixture to obtain a soil conditioner.

[0161] Comparative Example 4

[0162] This comparative example provides a soil conditioner, similar to Example 4, except that no compound phosphate fertilizer is added during the preparation of the hydrogel microbeads; specifically, the soil conditioner includes 15 kg of organic material, 0.5 kg of microbial inoculant, and 35 kg of modified hydrogel microbeads.

[0163] The 15kg organic material is composed of a mixture of 10kg humic acid and 5kg lignin.

[0164] 0.5 kg of microbial inoculant is a mixture of 0.2 kg of microalgae and 0.3 kg of yeast;

[0165] The method for preparing modified hydrogel microspheres includes the following steps:

[0166] S1. Stir 5g of 1wt% sodium alginate aqueous solution at 25℃ and 550rpm for 2h to obtain a mixed suspension for later use.

[0167] S2. The mixed suspension in S1 was injected into 250 mL of phosphogypsum extract containing 3 wt% calcium ions (the preparation of phosphogypsum extract is as described above) using a syringe pump with a needle diameter of 1 mm. The mixture was stirred at 200 rpm and 25 °C for 60 min, allowed to stand for 3 h, filtered, and the filtered beads were washed 3 times with deionized water to obtain sustained-release microbeads.

[0168] S3. Soak the slow-release microbeads from S2 in a 0.4 mol / L chloroacetic acid aqueous solution (500 mL of chloroacetic acid solution to completely submerge the compound phosphate fertilizer slow-release microbeads), adjust the pH to 8 with a 0.02 mol / L sodium hydroxide aqueous solution, stir at 150 rpm and 25℃ for 10 h, filter, rinse the filtered spheres with deionized water until neutral, and dry at room temperature (25℃) to obtain modified hydrogel microbeads.

[0169] The preparation method of the above-mentioned soil conditioner includes:

[0170] Mix 15 kg of organic material and 0.5 kg of microbial inoculant to obtain a mixture;

[0171] 35 kg of modified hydrogel microbeads were mixed with the mixture to obtain a soil conditioner.

[0172] Performance testing

[0173] Sustained-release rate test

[0174] 0.5g of the soil conditioner prepared in Examples 1-4 and Comparative Examples 1-3 (no phosphorus release test was performed in Comparative Example 4 because no compound phosphate fertilizer was added) were placed in 100mL of distilled water. The system was stabilized at room temperature for 10h, 20h, 40h, 80h, 160h, and 300h, respectively. Then, 5mL of supernatant was extracted, and 5mL of distilled water was added to the system. The extracted supernatant was then filtered through a 0.45μm aqueous filter membrane, the phosphorus concentration was measured, and the cumulative phosphorus release was calculated using the following formula:

[0175] Phosphorus release (%) = (C t ×V 总) / m0×100%

[0176] In the formula: C t V represents the mass concentration of phosphorus in the supernatant at time t, in g / L. 总 100 mL is the total volume of the solution; m0 refers to the total weight of phosphorus in the hydrogel beads, in g.

[0177] The test results are shown in Table 2.

[0178] Table 2 - Phosphorus release from soil conditioners prepared in different embodiments

[0179]

[0180] As shown in Table 2, the phosphorus release in Examples 1-4, which contain organic materials, microbial agents, and modified hydrogel microspheres (containing phosphate fertilizer), gradually increases over time, and the release amount is relatively controllable. The phosphorus release in Comparative Example 1 (without organic materials) and Comparative Example 2 (without microbial agents) is generally higher than that in the examples. For example, after 300 hours, Comparative Example 1 reaches 58.34% and Example 1 reaches 53.43%, indicating that organic materials and microbial agents can synergistically delay phosphorus release. The release amount in Comparative Example 3 (without carboxylation modification) is also higher than that in the examples, reflecting the regulatory effect of carboxylation modification on slow release. Overall, the synergistic combination of organic-inorganic-microorganisms, combined with carboxylation modification and other processes, can optimize the phosphorus slow-release performance of soil conditioners. The comparative examples, from the opposite perspective, verify the necessity of key components and processes for achieving reasonable phosphorus slow release, providing a basis for optimizing soil conditioner formulations.

[0181] Material water absorption capacity test

[0182] 0.5 g of the soil conditioner prepared in Examples 1-4 and Comparative Examples 1-4 was placed in 100 mL of distilled water. The system was stabilized at room temperature for 2 h, 4 h, 8 h, and 12 h, respectively. Then, it was taken out and weighed to obtain the weight (m) of the soil conditioner at that time. t And calculate the swelling ratio SR (g / g) using the following formula:

[0183] SR(g / g)=(m t -0.5) / 0.5

[0184] The test results are shown in Table 3.

[0185] Table 3 - Water absorption capacity of soil conditioners prepared in different embodiments

[0186]

[0187] As can be seen from Table 3, the swelling rate (reflecting water absorption capacity) of Examples 1-4 gradually increased over time due to the inclusion of organic materials, microbial agents, and modified hydrogel microspheres, and the overall values ​​were relatively high. For example, Example 1 reached 1476 g / g after 12 hours, demonstrating the good water absorption performance imparted by the synergistic effect of organic-inorganic-microbial processes. The swelling rates of Comparative Example 1 (without organic materials) and Comparative Example 2 (without microbial agents) were much lower than those of the Examples. For example, Comparative Example 1 was only 186 g / g after 12 hours, indicating that organic materials and microbial agents can synergistically improve water absorption capacity. Although the swelling rates of Comparative Example 3 (without carboxylation modification) and Comparative Example 4 (without phosphate fertilizer / with modification but lacking key fertilizer) were lower than those of the Examples, they were higher than those of Comparative Examples 1 and 2, demonstrating the positive effect of carboxylation modification and other processes on water absorption, and also reflecting that the influence of components such as phosphate fertilizer on water absorption capacity is relatively indirect. Overall, the rational combination and process optimization of organic, inorganic and microbial components can enhance the water absorption capacity of soil conditioners. The comparative model verifies the importance of key components for water absorption function from the opposite perspective, provides a reference for formula optimization, and helps to develop soil conditioners with better water retention performance.

[0188] Soil water retention capacity test

[0189] Determination of soil moisture loss rate: 100g of dry soil was mixed thoroughly with 2g of the soil conditioner prepared in Examples 1-4 and Comparative Examples 1-4 in a container. Another 100g of dry soil without added soil conditioner was used as a control group. 100mL of distilled water was poured into each container and weighed (W0). The mixed soils were then placed under natural light and weighed at 4, 8, 12, and 20 days (W0). n The soil moisture loss rate is calculated using the following formula:

[0190] Soil moisture loss rate (%) = (W0 - W) n ) / W0×100%

[0191] The test results are shown in Table 4.

[0192] Table 4 - Soil water retention capacity of soil conditioners prepared in different embodiments

[0193]

[0194]

[0195] As shown in Table 4, Examples 1-4, containing organic materials, microbial agents, and modified hydrogel microspheres, exhibited significantly lower soil moisture loss rates than the control group. Furthermore, their water retention advantages continued to manifest over time. For instance, Example 2 showed a moisture loss rate of only 40.69% after 20 days, far lower than the 84.39% of the control group, indicating that the synergistic effect of organic-inorganic-microbial agents effectively locks in water. Example 4, through process optimization, achieved even better water retention (38.41% after 20 days), validating the benefits of innovative processes on water retention. Comparative Examples 1-4, lacking key components or processes, had higher moisture loss rates than the examples. For instance, Comparative Example 4 reached 70.12% after 20 days, conversely confirming that "organic-inorganic-microbial synergy + process optimization" is the core logic for improving soil water retention. Overall, this demonstrates that a reasonable formula and process enable the conditioner to achieve efficient water retention. The comparative examples, in turn, support the necessity of key design, providing a basis for optimizing the water retention performance of soil conditioners.

[0196] Soil bulk density test

[0197] 0.5g of the soil conditioners prepared in Examples 1, 3, and Comparative Examples 1-4 were placed in the soil, and soil samples (depth 0-20cm) were monitored after 0, 15, 30, and 60 days. 100g of dry soil without added soil conditioner was used as a control group. Five points were randomly selected in the sample plot, and a ring sampler (inner diameter 6.18cm, height 2cm, volume 60cm³) was used. 3 Press the ring cutter vertically into the soil; remove the ring cutter, scrape the soil at both ends and weigh it, dry it at 105℃ for 24 hours, weigh it again (m1), and calculate the soil bulk density using the following formula;

[0198] Soil bulk density ρb (g / cm³) 3 ) = m1 / ring cutter volume

[0199] Table 5 - Soil bulk density of soil conditioners prepared in different embodiments

[0200]

[0201] As shown in Table 5, the soil bulk density of the control group decreased slowly over time; the soil bulk density of Examples 1-4 decreased more significantly due to the addition of an organic-inorganic-microbial composite conditioner, with Examples 2 and 4 reaching 1.29 g / cm³ at 60 days. 3 1.28g / cm 3 This demonstrates that the conditioner can effectively improve soil structure and increase looseness, and the effect increases over time. Comparative Examples 1-4, due to the lack of key components or processes, showed a smaller decrease in bulk density compared to the examples; for instance, Comparative Example 4 showed a decrease of 1.36 g / cm³ at 60 days. 3This, in turn, confirms the necessity of synergistic organic-inorganic-microbial processes and rational technology for optimizing soil bulk density. Overall, rationally formulated soil conditioners can continuously reduce soil bulk density and improve soil physical structure, thus supporting the importance of key design from the opposite perspective and providing technical reference for soil structure improvement.

[0202] Soil total porosity test

[0203] Soil density ρs, ρs = 2.65 g / cm³ 3 Based on the soil bulk density, the total soil porosity can be calculated using the following formula;

[0204] Total soil porosity (%) = [1 - (ρb / ρs)] × 100

[0205] Table 6 - Total Soil Porosity of Soil Conditioners Prepared in Different Examples

[0206]

[0207] As shown in Table 6, the total porosity of the soil in the control group increased slowly over time. In Examples 1-4, due to the addition of an organic-inorganic-microbial composite conditioner, the porosity increased significantly over time. For example, in Example 3, the porosity reached 54.34% after 60 days, indicating that the conditioner can effectively optimize soil structure and enhance permeability. The change in porosity reflects the synergistic effect of components and processes on porosity regulation. In Comparative Examples 1-4, due to the lack of key components or processes, the increase in porosity was lower than that of the examples. For example, in Comparative Example 2, the porosity was 50.57% after 60 days, which conversely confirms the necessity of the synergistic effect of organic-inorganic-microbial processes and complete processes for improving soil porosity.

[0208] Soil alkaline phosphatase activity test

[0209] 0.5g of the soil conditioners prepared in Examples 1, 3, and Comparative Examples 1-4 were placed in the soil, and soil samples (depth 0-20cm) were monitored after 0, 15, 30, and 60 days. 100g of dry soil without added soil conditioner was taken as a control group. Soil samples from the 0-20cm soil layer under different treatments were collected using a five-point method. After removing visible impurities (stones, roots, etc.), the five samples were thoroughly mixed, passed through a 1mm sample sieve, and stored at -20℃ for soil enzyme activity determination. Soil enzyme activity was determined (according to "Soil Enzymes and Their Research Methods" (by Guan Songyin, published by Agricultural Press in 1986)) using the sodium p-nitrophenolate phosphate colorimetric method to determine soil alkaline phosphatase activity.

[0210] Table 7 - Soil phosphatase activity of soil conditioners prepared in different embodiments

[0211]

[0212] As shown in Table 7, the soil phosphatase activity in the control group decreased over time, while in Examples 1-4, due to the addition of an organic-inorganic-microbial composite conditioner, the enzyme activity increased significantly over time. For example, in Example 3, the activity reached 13.68 mg / g at 60 days. -1 ·d -1 This indicates that the conditioner can effectively activate soil phosphatase and enhance soil biochemical activity. Comparative Examples 1-4, due to the lack of key components or processes, showed a smaller increase in enzyme activity compared to the examples; for instance, Comparative Example 4 showed only 3.12 mg / g at 60 days. -1 ·d -1 This, in turn, confirms the necessity of synergistic effects between organic, inorganic, and microbial processes, as well as appropriate technological processes, in enhancing soil phosphatase activity. Overall, rationally formulated soil conditioners can continuously activate soil phosphatase, optimize the soil biochemical environment, and provide a reference for soil fertility improvement.

[0213] It is understood that the technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0214] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. An organic-inorganic-microbial composite soil conditioner for water and fertilizer retention, characterized in that, It includes the following components by weight: 10-20 parts organic materials, 0.2-1 parts microbial inoculant, and 30-40 parts compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres; The organic materials include humic acid and lignin; The microbial agents include microalgae and yeast; The preparation method of the compound phosphate fertilizer slow-release carboxylated modified hydrogel microspheres includes the following steps: The compound phosphate fertilizer was dispersed in an aqueous solution of sodium alginate to obtain a mixed suspension; The mixed suspension was injected into a calcium ion-containing solution and filtered to obtain compound phosphate fertilizer slow-release microbeads. The compound phosphate fertilizer slow-release microbeads were immersed in chloroacetic acid solution, the pH was adjusted to 7-8, stirred, and filtered to obtain compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads. The mass ratio of humic acid to lignin is (1~2):1; The mass ratio of the microalgae to the yeast is (1~2):(1~2); The mixed suspension was injected into a calcium ion-containing solution using a syringe pump with a needle diameter of 1-1.5 mm. The mixture was stirred at 200-250 rpm and 16-25℃ for 45-60 min, allowed to stand for 2-3 h, filtered, and washed to obtain compound phosphate fertilizer slow-release microbeads. The compound phosphate fertilizer includes superphosphate, triple superphosphate, and potassium dihydrogen phosphate. The mass ratio of potassium dihydrogen phosphate, superphosphate, and triple superphosphate is (1~2):(1~3):(0~2); The calcium ion-containing solution includes at least one of CaCl2 solution, CaSO4 solution, Ca(NO3)2 solution, and phosphogypsum leachate; The mass concentration of the sodium alginate aqueous solution is 1-2%; The mass concentration of the calcium ion-containing solution is 2-4%; The concentration of the chloroacetic acid solution is 0.2~0.5 mol / L; The mass-to-volume ratio of the compound phosphate fertilizer, sodium alginate aqueous solution, and calcium ion-containing solution is (3~4)g:(5~7)g:(100~250)mL; The compound phosphate fertilizer slow-release microbeads were immersed in chloroacetic acid solution, and the pH was adjusted to 7-8 using 0.02-0.1 mol / L sodium hydroxide aqueous solution. After stirring and filtration, the compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads were obtained.

2. The organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner as described in claim 1, characterized in that, The compound phosphate fertilizer was dispersed in an aqueous solution of sodium alginate and stirred at 16-25℃ and 550-650 rpm for 1-2 h to obtain a mixed suspension. The compound phosphate fertilizer slow-release microbeads were immersed in chloroacetic acid solution, the pH was adjusted to 7-8, and the mixture was stirred at 60-200 rpm and 16-25℃ for 8-11 h. The mixture was then filtered, washed until neutral, and dried to obtain compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads.

3. A method for preparing an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner as described in any one of claims 1 to 2, characterized in that, Includes the following steps: The organic materials and microbial agents are mixed evenly to obtain a mixture; By mixing compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads with the mixture, an organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner is obtained.

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