Organic-inorganic-microbial composite water and fertilizer retention soil conditioner and preparation method thereof

Abstract

The invention provides an organic-inorganic-microbial composite water and fertilizer retention soil conditioner and a preparation method thereof. The organic-inorganic-microbial composite water and fertilizer retention soil conditioner comprises an organic material, a microbial agent and composite phosphate fertilizer slow-release carboxylated modified hydrogel microbeads (inorganic material), the compound phosphate fertilizer slow-release carboxylated modified hydrogel microbeads are mixed with organic materials such as humic acid and a microbial agent, so that the phosphorus slow-release effect and the soil water absorption and retention effect are further improved, and the compound phosphate fertilizer slow-release hydrogel microbeads have high water absorption and retention and fertilizer slow-release functions, can effectively improve soil, increase the soil water retention and phosphate fertilizer effectiveness, improve the enzyme activity of the soil and improve the fertilizer utilization rate. Soil moisture and fertility loss is reduced; the raw materials are wide in source, low in cost, safe and harmless, the preparation process is simple, and the prepared soil conditioner is harmless to the soil environment, has high water absorption and water retention and a fertilizer slow release function, can effectively improve soil and can be used for enhancing the water retention and physicochemical properties of the soil.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil improvement and remediation, and particularly relates to an organic-inorganic-microbial composite water and fertilizer retaining soil conditioner and a preparation method thereof. BACKGROUND

[0002] With the rapid development of agricultural economy, the utilization rate of soil is gradually increasing, but this high-intensity and high-frequency utilization also brings a series of serious problems to the soil. Long-term application of pesticides can cause soil compaction and decline in fertility; and indiscriminate use of chemical fertilizer products can reduce the fertilizer efficiency, and ultimately cause irreversible damage to the soil quality.

[0003] Compared with traditional pesticides and chemical fertilizers, the soil conditioner can be formulated according to different soil problems, and can solve the current significant problems of the soil in a targeted manner, and can provide the test soil with three major functions of water retention, fertilizer retention and air permeability. Through the application of agricultural water-retaining agent and organic material, the soil environment can be effectively adjusted, so as to solve the problems of soil compaction, poor water retention and decline in fertilizer efficiency. Moreover, the raw materials used for preparing the soil conditioner are safe and harmless, and are environmentally friendly, and generally do not cause secondary pollution.

[0004] For the soil which is extremely short of water and poor in water and fertilizer retention, a soil conditioner with high water and fertilizer retention is needed, and the type of water-retaining agent in the raw material is required to be high. Generally, the water-retaining agent is mainly a superabsorbent polymer, which is derived from a physical or chemical cross-linked polymer. Due to its porous structure and rich hydrophilic groups, it can absorb and store a large amount of water for the soil. However, the superabsorbent polymer currently used mainly comes from petrochemical products, which is not only expensive, but also has poor degradability when applied to the soil, and is easy to cause environmental hazards, so the application is limited.

[0005] The prior art discloses an organic-inorganic composite superabsorbent water-retaining material and a preparation method thereof. The inorganic clay is mixed with an alkali cellulose solution, and then mixed with a high molecular cross-linking agent to prepare a high water-retaining material. Through the combination of inorganic clay and high molecular polymer, the structural strength and physical properties of the material are improved, and the self-crosslinking density of the high molecular polymer is reduced, so that the water absorption and swelling properties of the material are increased, and the water retention capacity of the soil is well adjusted. However, the high water-retaining material provided by the present application uses a large amount of sodium hydroxide in the preparation process, so that the material as a whole is alkaline, which may cause soil alkalization during use, and has a negative impact on the acid-base environment of the soil.

[0006] The prior art discloses an aerogel soil water and fertilizer retaining agent and a preparation process thereof, and the water and fertilizer retaining agent is prepared by mixing and fermenting aerogel, microbial agents, inorganic fertilizer and organic fertilizer.

[0007] At present, researches on composite soil conditioners are emerging in endlessly, but most of the preparation processes are complicated, the conditions are harsh, and the effects are single, and the water retention, fertilizer retention and conditioning effects cannot be simultaneously achieved. SUMMARY

[0008] In order to solve the defects in the prior art, the present application provides an organic-inorganic-microbial composite water and fertilizer retaining soil conditioner and a preparation method thereof.

[0009] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0010] In the first aspect, the present application provides an organic-inorganic-microbial composite water and fertilizer retaining soil conditioner, which comprises organic materials, microbial agents and composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads.

[0011] The organic materials comprise humic acid and lignin.

[0012] The microbial agents comprise microalgae and yeast.

[0013] Preferably, the preparation method of the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads comprises the following steps:

[0014] The composite phosphorus fertilizer is dispersed in a sodium alginate aqueous solution to obtain a mixed suspension;

[0015] The mixed suspension is injected into a calcium ion-containing solution, filtered, and the composite phosphorus fertilizer slow-release microbeads are obtained.

[0016] The composite phosphorus fertilizer slow-release microbeads are immersed in a chloroacetic acid solution, the pH is adjusted to 7-9, stirred, filtered, and the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads are obtained.

[0017] Preferably, the preparation method comprises the following components by weight: 10-20 parts of organic materials, 0.2-1 parts of microbial agents, and 30-40 parts of composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads.

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

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

[0020] Preferably, the composite phosphorus fertilizer is dispersed in a sodium alginate aqueous solution, stirred at 16-25°C and 550-650 rpm for 1-2 h to obtain a mixed suspension;

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

[0022] The composite phosphorus fertilizer slow-release microbeads are immersed in a chloroacetic acid solution, the pH is adjusted to 7-9, stirred at 60-200 rpm and 16-25°C for 8-11 h, filtered, washed to neutral, and dried to obtain composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads.

[0023] Preferably, the composite phosphorus 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 leaching solution.

[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-volume ratio of the composite phosphorus fertilizer, sodium alginate aqueous solution, and calcium ion-containing solution is (3-4) g:(5-7) g:(100-250) mL.

[0030] Preferably, the composite phosphorus fertilizer slow-release microbeads are immersed in a chloroacetic acid solution, and a 0.02-0.1 mol / L sodium hydroxide aqueous solution is used to adjust the pH to 7-9, and the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads are obtained by stirring and filtering.

[0031] In a second aspect, the present application also provides a preparation method of the organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner, comprising the following steps:

[0032] mixing the organic material and the microorganism agent uniformly to obtain a mixture;

[0033] mixing the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads with the mixture to obtain the organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner.

[0034] The organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner and the preparation method thereof have the following effects compared with the prior art:

[0035] 1. The organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner comprises the organic material, the microorganism agent and the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads (inorganic material);The composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads are mixed with the organic material such as humic acid and the microorganism agent, further improve the slow-release effect of phosphorus and the water absorption effect of soil, and have high water absorption and slow-release function of fertilizer, can effectively improve the soil, increase the water retention of soil and the availability of phosphorus fertilizer, improve the enzyme activity of soil, and reduce the loss of soil moisture and fertility;

[0036] 2. The composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads are obtained by mixing the composite phosphorus fertilizer with sodium alginate aqueous solution, injecting the mixed suspension into a calcium ion-containing solution, and forming sodium alginate gel after cross-linking of the sodium alginate aqueous solution with calcium ions;By means of the gelation process, the composite phosphorus fertilizer is loaded, and a gel microbead structure is constructed;By utilizing the structural characteristics of the gel microbead, the release rate of the phosphorus fertilizer in the soil can be effectively prolonged;Further, the composite phosphorus fertilizer slow-release microbead is carboxylated and modified by chloroacetic acid, so that more carboxyl groups are loaded on the gel microbead, the water absorption unit in the gel microbead is improved, and the water absorption and retention performance of the microbead is further improved;

[0037] 3. Based on the purposes of water retention, fertilizer retention and conditioning, the organic material such as humic acid and lignin can not only adjust the soil acid-base environment and the activity of nutrient elements, promote the formation of soil aggregate structure, increase the porosity, but also provide substrates for soil and microbial enzyme activity;The organic acid (such as citric acid, oxalic acid) secreted by the microorganism agent such as yeast and microalgae can dissolve the fixed phosphate in the soil, and can secrete various enzymes during the mixing process with the organic material to accelerate the conversion of organic matter;The organic material and the microorganism agent both contain a large number of hydrophilic functional groups, which can improve the overall water retention, and can also promote the activation of nutrient elements during the contact with the gel microbead;

[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] The application provides an organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner, which comprises organic materials, microorganism agents and composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads.

[0043] The organic materials comprise humic acid and lignin.

[0044] The microorganism agents comprise microalgae and yeast.

[0045] The organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner of the application 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 the organic materials such as humic acid and the microorganism agents, the slow-release effect of phosphorus and the water absorption effect of soil are further improved, the water and fertilizer slow-release functions are high, the soil can be effectively improved, the water retention and the availability of phosphorus fertilizer of soil are increased, the enzyme activity of soil is improved, and the loss of water and fertilizer of soil is reduced.

[0046] In the application, the organic materials comprise humic acid and lignin, wherein the humic acid is a kind of organic substance formed through the decomposition and transformation of the remains of animals and plants by microorganisms, and the lignin is the main component of lignocellulose biomass, which is synthesized by the cell wall of higher plants and has good biocompatibility. Both the two kinds of organic materials contain rich functional groups, which can promote the formation of soil aggregate structure, improve the air permeability and water retention of soil, promote nutrient absorption and stabilize the pH of soil. Mixing the two kinds of organic materials with the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads can also reduce the fixation of fertilizer elements in soil through complexation and other effects, so as to achieve the purpose of slow release of fertilizer efficiency.

[0047] In the application, the microorganism agents comprise microalgae and yeast, wherein the microalgae are a kind of low-eukaryotic autotrophic organisms with small individual size and simple structure, which contain nutrients such as nitrogen, phosphorus and trace elements, and biological active substances that can promote the growth of plants and animals and improve the quality of agricultural products. Due to the characteristics of the microbial cells of microalgae, the microalgae can effectively absorb and release nutrients such as nitrogen, phosphorus and potassium when used in soil, and can also play a role in releasing phosphorus in soil, so as to promote the activation of soil phosphorus and improve the soil structure. For some specific types of microalgae such as blue-green algae, the microalgae can also play a role in nitrogen fixation, which is helpful to improve the soil fertility. The yeast is a kind of aquatic single-cell eukaryotic organism, which has a large number of hydrophilic functional groups, including amide groups, phosphate groups, amines, carboxyl groups and hydroxyl groups, can provide a large number of hydrophilic groups, and then improve the water absorption and retention capacity of the material. The microorganism agents can increase the microbial activity of soil, and promote the release and transformation of nutrients in the soil environment through the large number of functional groups carried by the microorganism agents, so as to further improve the soil structure.

[0048] In some embodiments, the preparation method of the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads comprises the following steps:

[0049] dispersing the composite phosphorus fertilizer in a sodium alginate aqueous solution to obtain a mixed suspension;

[0050] injecting the mixed suspension into a calcium ion-containing solution, filtering to obtain the composite phosphorus fertilizer slow-release microbeads;

[0051] immersing the composite phosphorus fertilizer slow-release microbeads in a chloroacetic acid solution, adjusting the pH to 7-9, stirring, filtering to obtain the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads.

[0052] The preparation method of the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads of the present application, by dispersing the composite phosphorus fertilizer in a sodium alginate aqueous solution to obtain a mixed suspension; injecting the mixed suspension into a calcium ion-containing solution, the sodium alginate aqueous solution will form a sodium alginate gel after crosslinking with calcium ions, and by means of this gelation process, the loading of the composite phosphorus fertilizer is realized, and a gel microbead structure is constructed; by utilizing the structural characteristics of the gel microbeads, the release rate of the phosphorus fertilizer in the soil can be effectively reduced, and the action time is prolonged; at the same time, by mixing the composite phosphorus fertilizer with sodium alginate, the mechanical strength and structural stability of the sodium alginate gel microbeads can be effectively improved; further, by carboxylating the composite phosphorus fertilizer slow-release microbeads with chloroacetic acid, more carboxyl groups are loaded on the gel microbeads, the water absorption units in the gel microbeads are increased, and the water absorption and water retention performance of the microbeads is further improved; the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads prepared by the present application have good pH responsiveness, the carboxylation modification loads more carboxyl groups on the gel microbead structure, the change of pH is accompanied by the protonation and deprotonation process of the carboxyl groups, thereby affecting the stability of the chemical bond and the stability of the overall structure, and further affecting the water absorption and release rate of the material and the release rate of the contents.

[0053] The present application is based on the three purposes of water retention, fertilizer retention and conditioning, and the organic materials such as humic acid and lignin not only can adjust the soil acid-base environment and nutrient element activity by utilizing their own characteristics, promote the formation of soil aggregate structure, increase the porosity, but also can provide substrates for soil and microbial enzyme activity; the organic acids (such as citric acid, oxalic acid) secreted by the microbial agents such as yeast and microalgae can dissolve the fixed phosphate in the soil, and can secrete various enzymes during the mixing process with the organic materials to accelerate the transformation of organic matter; the organic materials and microbial agents both contain a large number of hydrophilic functional groups, which can improve the overall water retention, and can also promote the activation of nutrient elements during the contact with the gel microbeads.

[0054] The organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner of the present application improves the physical and chemical structure and biological activity of soil through the synergistic effect of organic material, microbial agent and inorganic material (i.e. composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads): the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads absorb water to expand and form physical support, reduce the soil bulk density and build pore network; the organic material is decomposed by microorganisms to generate humus, which forms stable aggregates by cementing soil particles through functional groups; polysaccharides and gases produced by microbial metabolism further induce the formation of micropores; at the same time, the microbial agent and slow-release phosphorus fertilizer in the conditioner provide carbon and phosphorus sources for soil microorganisms, activate the expression of phosphatase genes, significantly improve the activity of alkaline phosphatase, and accelerate the mineralization of soil organic phosphorus. The synergistic effect significantly reduces the soil bulk density, improves the total porosity and the activity of alkaline phosphatase, and achieves the multiple improvement effects of "loose structure-pore optimization-enzymatic synergistic effect".

[0055] In some embodiments, the following components are included by weight: organic material 10-20 parts, microbial agent 0.2-1 part, composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads 30-40 parts.

[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 composite phosphorus fertilizer is dispersed in a sodium alginate aqueous solution, stirred at 16-25°C and 550-650 rpm for 1-2h to obtain a mixed suspension;

[0059] The mixed suspension is injected into a calcium ion-containing solution using a syringe pump with a needle diameter of 1-1.5mm, stirred at 200-250rpm and 16-25°C for 45-60min, allowed to stand for 2-3h, filtered, washed, and the composite phosphorus fertilizer slow-release microbeads are obtained;

[0060] The composite phosphorus fertilizer slow-release microbeads are immersed in a chloroacetic acid solution, the pH is adjusted to 7-9, stirred at 60-200rpm and 16-25°C for 8-11h, filtered, washed to neutral, and dried to obtain composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads.

[0061] In some embodiments, the composite phosphorus fertilizer includes superphosphate, triple superphosphate, and monopotassium phosphate;

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

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

[0064] Specifically, the preparation method of the phosphogypsum leaching solution comprises the following steps: crushing phosphogypsum and then soaking the phosphogypsum in water, and filtering to obtain the phosphogypsum leaching solution; wherein the mass concentration of calcium ions in the phosphogypsum leaching solution is 2-4%.

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

[0066] Table 1-Chemical composition of phosphogypsum

[0067]

[0068] Loss in Table 1 represents 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-volume ratio of the compound phosphorus fertilizer, the sodium alginate aqueous solution, and the calcium ion-containing solution is (3-4) g:(5-7) g:(100-250) mL.

[0073] In some embodiments, the compound phosphorus fertilizer slow-release microbeads are immersed in the chloroacetic acid solution, 0.02-0.1 mol / L sodium hydroxide aqueous solution is used to adjust the pH to 7-9, and then the mixture is stirred and filtered to obtain the compound phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads.

[0074] Specifically, the volume of the chloroacetic acid solution is not limited, as long as the compound phosphorus fertilizer slow-release microbeads are completely immersed.

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

[0076] Based on the same inventive concept, the application further provides a preparation method of the above-mentioned organic-inorganic-microorganism composite water and fertilizer retention soil conditioner, comprising the following steps:

[0077] Mixing the organic material and the microbial agent uniformly to obtain a mixture;

[0078] Mixing the compound phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads with the mixture to obtain the organic-inorganic-microorganism composite water and fertilizer retention soil conditioner.

[0079] The preparation method of the organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner has wide raw material sources, low cost, safety, harmlessness and simple preparation process.

[0080] The organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner and the preparation method thereof are further illustrated in the following specific examples. This part further illustrates the content of the present application in combination with specific examples, but should not be understood as a limitation of the present application. If not specifically stated, the technical means used in the examples are conventional means known to those skilled in the art. Unless specifically stated, the reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the art.

[0081] In the following examples and comparative examples, sodium alginate is purchased from Macklin Reagent, specifically S817374 sodium alginate, Cas No.: 9005-38-3;

[0082] Superphosphate is purchased from Macklin Reagent, specifically C822236 superphosphate monohydrate, Cas No.: 10031-30-8;

[0083] Humic acid is purchased from Macklin Reagent, specifically H742187 humic acid, Cas No.: 1415-93-6;

[0084] Lignin is purchased from Macklin Reagent, specifically L969910 lignin, Cas No.: 23363-35-1;

[0085] Yeast is purchased from Macklin Reagent, specifically Y750241 yeast powder;

[0086] Microalgae is Chlorella pyrenoidosa, purchased from Shanghai Zhongfeng Biotechnology Co., Ltd.

[0087] Example 1

[0088] The present example provides an organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner, which comprises 15 kg of organic material, 0.5 kg of microbial agent and 35 kg of composite phosphorus fertilizer slow-release carboxylated modified hydrogel microbeads.

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

[0090] The 0.5 kg of microbial agent is composed of 0.2 kg of microalgae and 0.3 kg of yeast;

[0091] The preparation method of the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microspheres comprises the following steps:

[0092] S1, 2g of potassium dihydrogen phosphate and 1g of superphosphate are ultrasonically dispersed in 5g of 1wt% sodium alginate aqueous solution, then stirred at 25℃ and 550rpm for 2h to obtain a mixed suspension, which is ready for use;

[0093] S2, the mixed suspension in S1 is injected into 250mL of 2wt% CaCl2 aqueous solution by using a syringe pump with a needle diameter of 1mm, stirred at 200rpm and 25℃ for 60min, and then left to stand for 3h; the obtained microspheres are filtered and washed with deionized water for 3 times to obtain composite phosphorus fertilizer slow-release microspheres;

[0094] S3, the composite phosphorus fertilizer slow-release microspheres in S2 are soaked in 0.4mol / L chloroacetic acid aqueous solution (the volume of the chloroacetic acid solution is 500mL to completely immerse the composite phosphorus fertilizer slow-release microspheres), and the pH is adjusted to 8 by using 0.02mol / L sodium hydroxide aqueous solution; the mixture is stirred at 150rpm and 25℃ for 10h, filtered, washed with deionized water until neutral, and dried at room temperature (25℃) to obtain composite phosphorus fertilizer slow-release carboxylated modified hydrogel microspheres.

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

[0096] 15kg of organic material and 0.5kg of microbial agent are mixed to obtain a mixture;

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

[0098] Example 2

[0099] The present embodiment provides an organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner, which comprises 10kg of organic material, 0.6kg of microbial agent, and 40kg of composite phosphorus fertilizer slow-release carboxylated modified hydrogel microspheres;

[0100] The 10kg of organic material is composed of 5kg of humic acid and 5kg of lignin;

[0101] The 0.6kg of microbial agent is composed of 0.3kg of microalgae and 0.3kg of yeast;

[0102] The preparation method of the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microspheres comprises the following steps:

[0103] S1, 3g of potassium dihydrogen phosphate and 1g of calcium superphosphate were ultrasonically dispersed in 6g of 2wt% sodium alginate aqueous solution, and then stirred at 25°C and 650rpm for 1.5h to obtain a mixed suspension, which was prepared for use;

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

[0105] S3, the composite slow-release phosphate fertilizer microspheres in S2 were soaked in 0.3mol / L chloroacetic acid aqueous solution (the volume of the chloroacetic acid solution was 500mL to completely immerse the composite slow-release phosphate fertilizer microspheres), and the pH was adjusted to 8 by using 0.05mol / L sodium hydroxide aqueous solution. The mixture was stirred at 200rpm and 25°C for 9h, filtered, rinsed with deionized water until neutral, and dried at room temperature (25°C) to obtain composite slow-release carboxylated modified hydrogel microspheres of phosphate fertilizer.

[0106] The preparation method of the organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner described above comprises the following steps:

[0107] 10kg of organic material and 0.6kg of microbial agent were mixed to obtain a mixture;

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

[0109] Example 3

[0110] The present embodiment provides an organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner, which comprises 15kg of organic material, 1kg of microbial agent, and 30kg of composite slow-release carboxylated modified hydrogel microspheres of phosphate fertilizer.

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

[0112] The 1kg of microbial agent is composed of 0.5kg of microalgae and 0.5kg of yeast;

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

[0114] S1, 2g of potassium dihydrogen phosphate and 2g of calcium superphosphate were ultrasonically dispersed in 7g of 2wt% sodium alginate aqueous solution, and then stirred at 25°C and 650rpm for 1.5h to obtain a mixed suspension, which was prepared for use;

[0115] S2, the mixed suspension in S1 is injected into 250 mL of 4 wt% CaCl2 aqueous solution by using a syringe pump with a needle diameter of 1.5 mm, stirred at 200 rpm and 25℃ for 45 min, left for 3 h, filtered, and the filtered spheres are rinsed with deionized water for 3 times to obtain the composite slow-release phosphate fertilizer microspheres;

[0116] S3, the composite slow-release phosphate fertilizer microspheres in S2 are soaked in 0.5 mol / L aqueous solution of chloroacetic acid (the volume of the chloroacetic acid solution is 500 mL to completely immerse the composite slow-release phosphate fertilizer microspheres), and the pH is adjusted to 9 by using 0.08 mol / L aqueous solution of sodium hydroxide, stirred at 180 rpm and 25℃ for 11 h, filtered, and the filtered spheres are rinsed to neutral with deionized water, and dried at room temperature (25℃) to obtain the composite slow-release carboxylated modified hydrogel microspheres of phosphate fertilizer.

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

[0118] 15 kg of organic material and 1 kg of microbial agent are mixed to obtain a mixture;

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

[0120] Example 4

[0121] The present example provides an organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner, which is the same as Example 1, except that in the preparation of the composite slow-release carboxylated modified hydrogel microspheres of phosphate fertilizer, 250 mL of 3 wt% phosphogypsum leaching solution is used in step S2.

[0122] Specifically, the organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner comprises 15 kg of organic material, 0.5 kg of microbial agent, and 35 kg of the composite slow-release carboxylated modified hydrogel microspheres of phosphate fertilizer.

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

[0124] The 0.5 kg of microbial agent is composed of 0.2 kg of microalgae and 0.3 kg of yeast;

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

[0126] S1, 2 g of potassium dihydrogen phosphate and 1 g of calcium superphosphate are ultrasonically dispersed in 5 g of 1 wt% sodium alginate aqueous solution, then stirred at 25℃ and 550 rpm for 2 h to obtain a mixed suspension, which is ready for use;

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

[0128] S3, the composite slow-release phosphate fertilizer microspheres in S2 are soaked in a 0.4 mol / L aqueous solution of chloroacetic acid (the volume of the chloroacetic acid solution is 500 mL to completely immerse the composite slow-release phosphate fertilizer microspheres), and the pH is adjusted to 8 using a 0.02 mol / L aqueous solution of sodium hydroxide, stirred at 150 rpm and 25°C for 10 h, filtered, and the filtered spheres are rinsed to neutral with deionized water, and dried at room temperature (25°C) to obtain composite slow-release carboxylated modified hydrogel microspheres of phosphate fertilizer.

[0129] The preparation method of the organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner described above comprises:

[0130] 15 kg of organic material and 0.5 kg of microbial agent are mixed to obtain a mixture;

[0131] 35 kg of composite slow-release carboxylated modified hydrogel microspheres of phosphate fertilizer are mixed with the mixture to obtain an organic-inorganic-microorganism composite water 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 material is added; specifically, the soil conditioner comprises 0.5 kg of microbial agent and 35 kg of composite slow-release carboxylated modified hydrogel microspheres of phosphate fertilizer.

[0134] The 0.5 kg of microbial agent is obtained by mixing 0.2 kg of microalgae and 0.3 kg of yeast;

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

[0136] S1, 2 g of potassium dihydrogen phosphate and 1 g of calcium superphosphate are ultrasonically dispersed in 5 g of a 1 wt% sodium alginate aqueous solution, then stirred at 25°C and 550 rpm for 2 h to obtain a mixed suspension, which is ready for use;

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

[0138] S3, the composite phosphorus fertilizer slow-release microspheres in S2 are soaked in a 0.4 mol / L chloroacetic acid aqueous solution (the volume of the chloroacetic acid solution is 500 mL to completely immerse the composite phosphorus fertilizer slow-release microspheres), a 0.02 mol / L sodium hydroxide aqueous solution is used to adjust the pH to 8, stirring is performed at 150 rpm and 25°C for 10 h, filtration is performed, the filtered spheres are washed to neutral with deionized water, and drying is performed at room temperature (25°C) to obtain the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microspheres.

[0139] The preparation method of the soil conditioner described above comprises the following steps:

[0140] 0.5 kg of the microbial agent is mixed with 35 kg of the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microspheres to obtain the 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 agent is added; specifically, the soil conditioner comprises 15 kg of organic material, 35 kg of composite phosphorus fertilizer slow-release carboxylated modified hydrogel microspheres, and 0.5 kg of microbial agent.

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

[0144] The preparation method of the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microspheres comprises the following steps:

[0145] S1, 2 g of potassium dihydrogen phosphate and 1 g of calcium superphosphate are ultrasonically dispersed in 5 g of a 1 wt% sodium alginate aqueous solution, then stirring is performed at 25°C and 550 rpm for 2 h to obtain a mixed suspension, which is reserved for use;

[0146] S2, the mixed suspension in S1 is injected into 250 mL of a 2 wt% CaCl2 aqueous solution through a syringe pump with a needle diameter of 1 mm, stirring is performed at 200 rpm and 25°C for 60 min, standing is performed for 3 h, filtration is performed, and the filtered spheres are washed with deionized water for 3 times to obtain the composite phosphorus fertilizer slow-release microspheres;

[0147] S3, the composite phosphorus fertilizer slow-release microspheres in S2 are soaked in a 0.4 mol / L chloroacetic acid aqueous solution (the volume of the chloroacetic acid solution is 500 mL to completely immerse the composite phosphorus fertilizer slow-release microspheres), a 0.02 mol / L sodium hydroxide aqueous solution is used to adjust the pH to 8, stirring is performed at 150 rpm and 25°C for 10 h, filtration is performed, the filtered spheres are washed to neutral with deionized water, and drying is performed at room temperature (25°C) to obtain the composite phosphorus fertilizer slow-release carboxylated modified hydrogel microspheres.

[0148] The preparation method of the soil conditioner described above comprises the following steps:

[0149] Mix 35 kg of the composite slow-release phosphorus fertilizer carboxylated modified hydrogel microspheres with 15 kg of organic material to obtain an organic-inorganic-microorganism composite water and fertilizer retaining soil conditioner.

[0150] Comparative Example 3

[0151] This comparative example provides a soil conditioner, which is the same as Example 1, except that the composite slow-release phosphorus fertilizer hydrogel microspheres are not carboxylated modified; specifically, the soil conditioner includes 15 kg of organic material, 0.5 kg of microbial agent, and 35 kg of composite slow-release phosphorus fertilizer hydrogel microspheres.

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

[0153] The 0.5 kg of microbial agent is composed of 0.2 kg of microalgae and 0.3 kg of yeast;

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

[0155] S1, ultrasonically disperse 2 g of potassium dihydrogen phosphate and 1 g of calcium superphosphate in 5 g of 1 wt% sodium alginate aqueous solution, then stir at 25°C and 550 rpm for 2 h to obtain a mixed suspension, which is ready for use;

[0156] S2, inject the mixed suspension in S1 into 250 mL of 2 wt% CaCl2 aqueous solution using a syringe pump with a needle diameter of 1 mm, stir at 200 rpm and 25°C for 60 min, stand for 3 h, filter, and rinse the filtered spheres with deionized water for 3 times to obtain composite slow-release phosphorus fertilizer microspheres;

[0157] S3, rinse the composite slow-release phosphorus fertilizer microspheres in S3 to neutral with deionized water, and dry at room temperature to obtain composite slow-release phosphorus fertilizer hydrogel microspheres.

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

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

[0160] Mix 35 kg of the composite slow-release phosphorus fertilizer hydrogel microspheres with the mixture to obtain the soil conditioner.

[0161] Comparative Example 4

[0162] This comparative example provides a soil conditioner, which is the same as Example 4, except that no composite slow-release phosphorus fertilizer is added during the preparation of the hydrogel microspheres; specifically, the soil conditioner includes 15 kg of organic material, 0.5 kg of microbial agent, and 35 kg of modified hydrogel microspheres.

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

[0164] The 0.5 kg of microbial inoculant is composed of 0.2 kg of microalgae and 0.3 kg of yeast.

[0165] The method for preparing the modified hydrogel microbeads comprises the following steps:

[0166] S1. 5 g of a 1 wt% sodium alginate aqueous solution is stirred at 25°C and 550 rpm for 2 h to obtain a mixed suspension, which is ready for use.

[0167] S2. The mixed suspension in S1 is injected into 250 mL of a calcium ion-containing 3 wt% phosphogypsum leaching solution (the preparation of the phosphogypsum leaching solution is as shown above) using a syringe pump with a needle diameter of 1 mm, and stirred at 200 rpm and 25°C for 60 min, and then left to stand for 3 h. The filtered microspheres are washed with deionized water for 3 times, to obtain slow-release microbeads.

[0168] S3. The slow-release microbeads in S2 are soaked in 0.4 mol / L chloroacetic acid aqueous solution (the volume of the chloroacetic acid solution is 500 mL to completely immerse the slow-release microbeads), and the pH is adjusted to 8 using 0.02 mol / L sodium hydroxide aqueous solution. The solution is stirred at 150 rpm and 25°C for 10 h, and then filtered. The filtered microspheres are washed to neutral with deionized water, and dried at room temperature (25°C) to obtain modified hydrogel microbeads.

[0169] The method for preparing the soil conditioner comprises:

[0170] 15 kg of organic material and 0.5 kg of microbial inoculant are mixed to obtain a mixture.

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

[0172] Performance test

[0173] Release rate test

[0174] 0.5 g of the soil conditioner prepared in Examples 1-4 and Comparative Examples 1-3 (Comparative Example 4 does not contain composite phosphate fertilizer, so no phosphorus release amount test is performed) is placed in 100 mL of distilled water, and the system is stabilized in a room temperature environment for 10 h, 20 h, 40 h, 80 h, 160 h, and 300 h, respectively. Then, 5 mL of supernatant is extracted, and 5 mL of distilled water is added to the system. Then, the extracted supernatant is filtered using a 0.45 μm water filter membrane, the phosphorus concentration is detected, and the cumulative release amount of phosphorus is calculated using the following formula:

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

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

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

[0178] Table 2 - Phosphorus release amount of soil conditioners prepared in different examples

[0179]

[0180] As can be seen from Table 2, Examples 1-4, which contain organic materials, microbial agents, modified hydrogel microspheres (containing phosphorus fertilizer), show a gradual increase in phosphorus release over time, and the release amount is relatively controllable; the phosphorus release amount of Comparative Examples 1 (without organic materials) and Comparative Example 2 (without microbial agents) is higher than that of Examples, such as 58.34% for Comparative Example 1 and 53.43% for Example 1 at 300 h, indicating that organic materials and microbial agents can synergistically delay phosphorus release; the release amount of Comparative Example 3 (without carboxyl modification) is also higher than that of Examples, which reflects the regulating effect of carboxyl modification on slow release; overall, the synergistic cooperation of organic-inorganic-microorganisms, combined with carboxyl modification process, can optimize the phosphorus slow release performance of soil conditioners, and the key components and processes are necessary for achieving reasonable phosphorus slow release, which provides a basis for the optimization of soil conditioner formulations.

[0181] Material water absorption capacity test

[0182] 0.5 g of soil conditioners prepared in Examples 1-4 and Comparative Examples 1-4 was placed in 100 mL of distilled water, and the system was stabilized in a room temperature environment for 2 h, 4 h, 8 h, and 12 h, respectively, then taken out and weighed to obtain the weight (m t ) of the soil conditioner at that time and calculate the swelling rate SR (g / g) according to 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 examples

[0186]

[0187] As can be seen from Table 3, Examples 1-4 contain organic materials, microbial agents, modified hydrogel microspheres, and the swelling rate (water absorption capacity) gradually increases with time, and the overall value is high, such as Example 1, which reaches 1476 g / g at 12 h, which reflects the good water absorption performance of the organic-inorganic-microbial synergistic effect; Comparative Example 1 (without organic materials) and Comparative Example 2 (without microbial agents) have a much lower swelling rate than Examples, such as Comparative Example 1, which is only 186 g / g at 12 h, indicating that organic materials and microbial agents can synergistically improve water absorption capacity; Comparative Example 3 (without carboxylation modification) and Comparative Example 4 (without phosphorus fertilizer / modified but lacking key fertilizer) have a lower swelling rate than Examples but higher than Comparative Examples 1 and 2, which reflects the positive effect of carboxylation modification and other processes on water absorption, and also reflects the relatively indirect effect of phosphorus fertilizer and other components on water absorption capacity. Overall, the reasonable combination of organic-inorganic-microbial and process optimization can enhance the water absorption capacity of the soil conditioner, and the comparative examples verify the importance of key components for water absorption function from the opposite side, providing a reference for formula optimization and helping to develop soil conditioners with better water retention performance.

[0188] Soil water retention capacity test

[0189] Determination of soil water loss rate: 100 g of dry soil was mixed with 2 g of soil conditioner prepared in Examples 1-4 and Comparative Examples 1-4 in a container, and another 100 g of dry soil without soil conditioner was taken as a control group. 100 mL of distilled water was poured into each container and weighed (W0), then each group of mixed soil was placed in natural light conditions, and the weight (W n ) was measured at 4, 8, 12, and 20 days, respectively. The soil water loss rate was calculated as follows:

[0190] Soil water loss rate (%) = (W0-W n ) / W0x100%

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

[0192] Table 4 - Soil water retention capacity of soil conditioners prepared by different examples

[0193]

[0194]

[0195] As can be seen from Table 4, the water loss rates of Examples 1-4 are significantly lower than those of the control group due to the presence of organic materials, microbial agents and modified hydrogel microspheres, and the water retention advantage is continuously reflected as time goes on. For example, the water loss rate of Example 2 is only 40.69% at 20d, which is much lower than the 84.39% of the control group, indicating that the organic-inorganic-microbial synergistic effect can effectively lock water. Example 4 has a more optimal water retention effect (38.41% at 20d) through process optimization, verifying the gain of the innovative process on water retention. The water loss rates of Comparative Examples 1-4 are higher than those of Examples due to the absence of key components or processes. For example, the water loss rate of Comparative Example 4 is 70.12% at 20d, which inversely confirms that the "organic-inorganic-microbial synergistic effect + process optimization" is the core logic to improve soil water retention. Overall, the reasonable formulation and process enable the conditioner to achieve efficient water retention, and the comparative examples support the necessity of key design from the opposite side, providing a basis for optimizing the water retention performance of soil conditioners.

[0196] Soil bulk density test

[0197] 0.5g of the soil conditioner prepared in Examples 1, 3 and Comparative Examples 1-4 was placed in the soil, and the soil samples (depth 0-20cm) after 0, 15, 30, 60 days were monitored; 100g of dry soil without adding soil conditioner was taken as the control group. Five points were randomly selected in the sample plot, and a cutting ring (inner diameter 6.18cm, height 2cm, volume 60cm 3 ) was vertically pressed into the soil; the cutting ring was removed, the soil at both ends was scraped flat and weighed, and then dried at 105℃ for 24h, and weighed again (m1). The soil bulk density was calculated by the following formula:

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

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

[0200]

[0201] As can be seen from Table 5, the soil bulk density of the control group decreases slowly over time; the soil bulk density of Examples 1-4 decreases more significantly due to the addition of organic-inorganic-microbial composite conditioner. For example, the soil bulk densities of Examples 2 and 4 are 1.29g / cm 3 and 1.28g / cm 3 at 60d, respectively, indicating that the conditioner can effectively improve soil structure and increase porosity, and the effect is enhanced over time. The bulk density of Comparative Examples 1-4 decreases less than that of Examples due to the absence of key components or processes. For example, the bulk density of Comparative Example 4 is 1.36g / cm 3, reverse organic-inorganic-microorganism synergy and the necessity of reasonable process for optimizing soil bulk density. Overall, the soil conditioner with reasonable formula can continuously reduce the soil bulk density and improve the soil physical structure. The comparison from the opposite side supports the importance of key design and provides a technical reference for soil structure improvement.

[0202] Soil total porosity test

[0203] Soil density ρs, ρs = 2.65 g / cm 3 According to the soil bulk density, the total soil porosity can be calculated, and the total soil porosity is calculated by the following formula:

[0204] Soil total porosity (%) = [1-(ρb / ρs)]x100

[0205] Table 6 - Soil total porosity of soil conditioner prepared in different examples

[0206]

[0207] As can be seen from Table 6, the total soil porosity of the control group slowly increases over time; Examples 1-4 have added organic-inorganic-microorganism composite conditioner, and the porosity significantly increases over time, such as Example 3, which reaches 54.34% at 60d, indicating that the conditioner can effectively optimize the soil structure and enhance the air permeability, and the change in porosity reflects the regulation of component and process synergy on porosity; The porosity of Comparative Examples 1-4 is lower than that of Examples due to the lack of key components or processes, such as Comparative Example 2, which is 50.57% at 60d, which reversely proves the necessity of organic-inorganic-microorganism synergy and complete process for improving soil porosity.

[0208] Soil alkaline phosphatase activity test

[0209] 0.5g of soil conditioner prepared in Examples 1, 3 and Comparative Examples 1-4 was placed in the soil, and the soil samples (depth 0-20cm) after 0, 15, 30, 60 days were monitored; 100g of dry soil without adding soil conditioner was taken as the control group. Five-point method was used to collect 0-20cm soil layer under different treatments, and after removing visible impurities (stone, root, etc.), the five-point samples were thoroughly mixed, passed through 1mm sample screen and stored at -20℃ for soil enzyme activity determination; The determination of soil enzyme activity (according to "Soil Enzyme and Its Research Method" (Guan Songyin, published by Agricultural Press in 1986) was tested) was determined by p-nitrophenol sodium phosphate colorimetric method.

[0210] Table 7 - Soil phosphatase activity of soil conditioner prepared in different examples

[0211]

[0212] As can be seen from Table 7, the phosphatase activity of the control group soil decreases over time, while the phosphatase activity of Examples 1-4 significantly increases over time due to the addition of the organic-inorganic-microbial compound conditioner, such as 13.68 mg·g -1 ·d -1 at 60 d in Example 3, indicating that the conditioner can effectively activate soil phosphatase and enhance soil biochemical activity; the phosphatase activity of Comparative Examples 1-4 increases less than Examples due to the absence of key components or processes, such as only 3.12 mg·g -1 ·d -1 at 60 d in Comparative Example 4, which reversely proves the necessity of organic-inorganic-microbial synergy and reasonable process for improving soil phosphatase activity. Overall, the soil conditioner with a reasonable formula can continuously activate soil phosphatase and optimize the soil biochemical environment, providing a reference for soil fertility improvement.

[0213] It can be understood that any combination of the technical features of the above-described embodiments can be made. In order to make the description simple, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0214] The above is only a preferred embodiment of the present application, and only the technical principles of the present application are specifically described, and these descriptions are only for explaining the principles of the present application, and cannot be explained in any way as a limitation on the protection scope of the present application. Based on the explanation here, any modification, equivalent replacement and improvement made within the spirit and principles of the present application, and other specific embodiments of the present application that can be easily thought by those skilled in the art without creative labor, should be included in the protection scope of the present application.

Claims

1. An organic-inorganic-microbial composite soil conditioner for water and fertilizer retention, characterized in that, Including organic materials, microbial agents, and slow-release carboxylated modified hydrogel microspheres of compound phosphate fertilizer; The organic materials include humic acid and lignin; The microbial agents include microalgae and yeast.

2. The organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner as described in claim 1, characterized in that, 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 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.

3. The organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner as described in claim 1, characterized in that, It 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.

4. The organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner as described in claim 1, characterized in that, The mass ratio of humic acid to lignin is (1-2):1; The mass ratio of microalgae to yeast is (1-2):(1-2).

5. The organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner as described in claim 2, characterized in that, The compound phosphate fertilizer was 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. 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. 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.

6. The organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner as described in claim 2, characterized in that, 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(NO)3 solution, and phosphogypsum leachate.

7. The organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner as described in claim 2, characterized in that, 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.

8. The organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner as described in claim 2, characterized in that, 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.

9. The organic-inorganic-microbial composite water-retaining and fertilizer-retaining soil conditioner as described in claim 2, characterized in that, The compound phosphate fertilizer slow-release microbeads were immersed in chloroacetic acid solution, and the pH was adjusted to 7-9 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.

10. 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 9, 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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