Rice field soil conditioner and preparation method

Abstract

The application discloses a paddy field soil conditioner, which is prepared by mixing modified zeolite molecular sieve, biological fertilizer, polymeric bentonite, biochar and nano zero-valent iron according to a mass ratio of 20-25:30-35:25-30:15-20:5-8; the modified zeolite molecular sieve and the polymeric bentonite can effectively adsorb fertilization nutrients in the soil, greatly reduce the nutrient loss rate, improve the soil nutrient retention rate, reduce the use of chemical fertilizers, and are beneficial to sustainable agricultural development; the modified zeolite molecular sieve can also absorb water and release water when high-temperature weather occurs, effectively improve the soil structure, improve the water retention of the paddy field soil, and avoid the phenomenon that the planted rice is dead due to no timely water supplement in hot weather; meanwhile, the nano zero-valent iron and the biochar can adsorb and reduce and fix heavy metal ions existing in the soil, and reduce the heavy metal pollution in the paddy field soil.

Description

Technical Field

[0001] This invention relates to the field of farmland soil improvement technology, and in particular to a paddy field soil conditioner and its preparation method. Background Technology

[0002] The quality of paddy field soil directly affects the growth and yield of rice. Traditional soil improvement methods mainly include the application of chemical fertilizers and organic fertilizers, but these methods may have problems such as nutrient loss and environmental pollution. For example, a large amount of phosphate fertilizer lost into river water sources can lead to phosphorus pollution in water bodies, causing a large number of fish and other aquatic organisms to die.

[0003] Paddy soil often suffers from soil structure and nutrient imbalance due to long-term cultivation and fertilizer use. Currently, traditional soil conditioners are still used to treat paddy soil, but their functions are limited and cannot improve the nutrient retention rate of paddy soil. Some nutrients are still lost. At the same time, large amounts of nitrogen, phosphorus, and potassium fertilizers still need to be applied when cultivating paddy soil. However, paddy soil with low nutrient retention rate cannot make full use of the applied fertilizer nutrients. Therefore, this invention proposes a paddy soil conditioner and its preparation method to solve the problems existing in the prior art. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a paddy field soil conditioner and its preparation method. This conditioner, through the addition of modified zeolite molecular sieves and polymerized bentonite, effectively adsorbs fertilizer nutrients in the soil, significantly reducing nutrient loss, improving soil nutrient retention, and decreasing the use of chemical fertilizers, thus promoting sustainable agricultural development. The modified zeolite molecular sieves can also absorb water and release it during hot weather, effectively improving soil structure and enhancing the water retention capacity of paddy field soil, preventing rice plants from withering and dying due to insufficient watering in hot weather. Simultaneously, the combination of nano-zero-valent iron and biochar can adsorb and reduce heavy metal ions present in the soil, reducing heavy metal pollution in paddy field soil.

[0005] To achieve the objectives of this invention, the following technical solution is provided: a paddy field soil conditioner and its preparation method, comprising a mixture of modified zeolite molecular sieve, bio-fertilizer, polymerized bentonite, biochar, and nano-zero-valent iron, wherein the mass ratio of modified zeolite molecular sieve, bio-fertilizer, polymerized bentonite, biochar, and nano-zero-valent iron is 20-25:30-35:25-30:15-20:5-8. The modified zeolite molecular sieve is obtained after acid-base treatment. The polymerized bentonite is prepared by mixing and modifying potassium salt and phosphate and then mixing with xanthan gum. The bio-fertilizer is prepared by co-culturing nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and potassium-solubilizing bacteria and fermenting them together with a fermentation substrate.

[0006] A further improvement is that: the potassium salt is one of potassium chloride and potassium sulfate; the phosphate is one of calcium dihydrogen phosphate, ammonium dihydrogen phosphate, and superphosphate lime; the nitrogen-fixing bacteria is one of Azotobacter chrysodontiformis and Frankincense; the phosphate-solubilizing bacteria is one of Chromobacterium and Micrococcus; and the potassium-solubilizing bacteria is one of silicate bacteria and Bacillus KM2.

[0007] A method for preparing a paddy field soil conditioner includes the following steps:

[0008] Step 1: Preparation of modified zeolite molecular sieve: The molecular sieve is subjected to acid and alkali treatment with acid and alkali solutions in sequence, and then the acid-treated molecular sieve is acid washed and dried to obtain modified zeolite molecular sieve.

[0009] Step 2, Bio-fertilizer preparation: Nitrogen-fixing bacteria, phosphorus-solubilizing bacteria and potassium-solubilizing bacteria are co-cultured, then thoroughly mixed with fermentation substrate for fermentation treatment, and finally dried and pulverized to obtain bio-fertilizer;

[0010] Step 3: Preparation of polymerized bentonite: First, the bentonite is nano-ground and then humidified. Then, potassium salt and phosphate are mixed with it and added to xanthan gum viscous liquid and stirred to obtain polymerized bentonite.

[0011] Step 4: Preparation and adsorption of nano-zero valent iron: Nano-zero valent iron was prepared by electrochemical reduction, and then mixed with biochar for adsorption to obtain a modified complex.

[0012] Step 5, Preliminary mixing treatment: First, mix and stir the bio-fertilizer with the modified zeolite molecular sieve, then add the mixture to polymerized bentonite for mixing to obtain a premixed amendment;

[0013] Step 6: Mixing and granulation: Add the modified compound to the premixed amendment and stir to obtain the final mixture. Then place it in a granulator for extrusion granulation to obtain the soil amendment.

[0014] A further improvement is made in the following specific processing method in step one: First, the zeolite molecular sieve is subjected to heating and acid leaching with an aqueous solution of ethylenediaminetetraacetic acid (EDTA), then rinsed with hot distilled water and dried and calcined to obtain an acid-treated molecular sieve; then, the acid-treated molecular sieve is added to an aqueous solution of sodium hydroxide and heated for alkali treatment, then rinsed with hot distilled water and dried and calcined to obtain an acid-alkali treated molecular sieve; finally, the acid-alkali treated molecular sieve is subjected to heating and acid washing with a disodium EDTA solution, then rinsed with hot distilled water and dried to obtain a modified zeolite molecular sieve.

[0015] Further improvements are made in the following aspects: the concentration of the ethylenediaminetetraacetic acid aqueous solution is 0.18 mol / L; the concentration of the sodium hydroxide aqueous solution is 0.9 mol / L; the concentration of the disodium ethylenediaminetetraacetic acid solution is 0.11 mol / L; the heating treatment is carried out by heating to 65-100℃ in a silicone oil bath; the drying condition is drying at 130℃ for 4-5 hours; and the calcination condition is calcining the treated molecular sieve in a muffle furnace at 600℃ for 5 hours, followed by cooling and removal.

[0016] A further improvement is made in the following: In step two, the fermentation substrate is a mixture of straw and livestock manure. Specifically, the straw is first sterilized and cleaned, then dried and crushed with the livestock manure, and finally mixed with co-cultured multi-strain bacteria and sprinkled with water to maintain the moisture content of the fermentation material at 45%-55% for fermentation.

[0017] Further improvements are made in the following steps: In step three, the humidification treatment of bentonite involves mixing the nano-ground bentonite with deionized water, purifying and slurrying it to complete the humidification treatment. When mixing with potassium salt and phosphate, the potassium salt and phosphate are first prepared into a salt aqueous solution. Then, the salt aqueous solution is introduced into the humidified bentonite and stirred, followed by drying and grinding. Xanthan gum and deionized water are then heated and stirred at 60-80℃ to obtain a viscous liquid. Finally, the ground bentonite is added to the viscous liquid and stirred to obtain polymerized bentonite.

[0018] A further improvement is that: in step four, the preparation of nano-zero valent iron specifically involves dissolving iron salt in water to obtain an iron salt solution, then electrolyzing it with an applied current to reduce the iron salt on the cathode to generate nano-zero valent iron deposits, which are then removed, rinsed, and dried to obtain nano-zero valent iron; wherein the iron salt is one of ferric chloride, polyferric chloride, and polyferric sulfate.

[0019] The beneficial effects of this invention are as follows: By adding modified zeolite molecular sieves and polymerized bentonite, this invention can effectively adsorb fertilizer nutrients in the soil, greatly reduce the rate of nutrient loss, improve the soil nutrient retention rate, reduce the use of chemical fertilizers, and is conducive to sustainable agricultural development.

[0020] Modified zeolite molecular sieves can absorb water and release it when exposed to high temperatures, effectively improving soil structure and enhancing the water retention of paddy soil, thus preventing rice from dying due to insufficient watering in hot weather.

[0021] Meanwhile, the combination of nano-zero-valent iron and biochar can adsorb and reduce heavy metal ions in the soil, thereby reducing heavy metal pollution in paddy soil. This has important practical value and environmental significance in agricultural applications. Attached Figure Description

[0022] Figure 1This is a flowchart of the preparation method in Example 1 of the present invention.

[0023] Figure 2 This is a flowchart of the preparation method in Example 2 of the present invention. Detailed Implementation

[0024] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0025] Unless otherwise specified, all raw materials used in the embodiments of the present invention are obtained through conventional commercial channels.

[0026] Among them, *Azotobacter chrysophagus* was purchased from the China Center for Type Culture Collection (CCTCC), accession number CCTCC NO: M2016110; silicate bacteria were purchased from the China Center for Type Culture Collection of Wuhan University, accession number CCTCC No. M200040; and *Micrococcus* was purchased from the China General Microbiological Culture Collection Center (CGMCC), accession number CGMCC No. 7778.

[0027] The co-culture method of the compound bacteria in the example is as follows: the culture medium with the following composition is used: 0.4% yeast extract, 0.6% peptone, 5% brown sugar, 0.1% Tween-80, 0.05% sodium chloride, 0.05% dipotassium hydrogen phosphate, 0.05% magnesium sulfate, 0.05% calcium carbonate, and the remainder is water; the culture is carried out at 35°C on a shaker at 200 r / min for 24 hours; the inoculation ratio of the three bacteria is 1:1000.

[0028] Example 1

[0029] This embodiment provides a paddy field soil conditioner and its preparation method, comprising a mixture of modified zeolite molecular sieve, bio-fertilizer, polymerized bentonite, biochar, and nano-zero-valent iron. The mass ratio of the modified zeolite molecular sieve, bio-fertilizer, polymerized bentonite, biochar, and nano-zero-valent iron is 20:30:25:20:5. The modified zeolite molecular sieve is obtained after acid-base treatment. The polymerized bentonite is prepared by mixing and modifying potassium chloride and calcium dihydrogen phosphate and then mixing it with xanthan gum. The bio-fertilizer is prepared by co-culturing Azotobacter chrysophagus, Micrococcus, and silicate bacteria and fermenting them together with a fermentation substrate.

[0030] according to Figure 1 As shown in the figure, this embodiment provides a method for preparing a paddy field soil conditioner, characterized by the following steps:

[0031] Step 1: Preparation of modified zeolite molecular sieve. The molecular sieve is treated with acid and alkali solutions, and then the treated molecular sieve is acid washed and dried to obtain modified zeolite molecular sieve.

[0032] The specific treatment method is as follows: First, the zeolite molecular sieve is treated with an acid leaching process by heating it to 70°C in a silicone oil bath with an aqueous solution of 0.18 mol / L ethylenediaminetetraacetic acid. Then, it is rinsed with hot distilled water and dried at 130°C for 4 hours. The treated molecular sieve is then placed in a muffle furnace and calcined at 600°C for 5 hours before being cooled and removed to obtain the acid-treated molecular sieve.

[0033] Then, the acid-treated molecular sieve was added to a 0.9 mol / L sodium hydroxide aqueous solution and heated to 65°C in a silicone oil bath for alkali treatment. After rinsing with hot distilled water, it was dried at 130°C for 4-5 hours. The treated molecular sieve was then placed in a muffle furnace and calcined at 600°C for 5 hours before being cooled and removed to obtain the acid-alkali treated molecular sieve.

[0034] Finally, the acid-base treated molecular sieve was subjected to a heating and acid washing treatment using a 0.11 mol / L disodium ethylenediaminetetraacetate solution heated to 65°C in a silicone oil bath. After rinsing with hot distilled water, it was dried at 130°C for 4 hours to obtain the modified zeolite molecular sieve.

[0035] Step 2: Bio-fertilizer fermentation preparation. First, nitrogen-fixing bacteria, phosphorus-solubilizing bacteria and potassium-solubilizing bacteria are co-cultured. Then, they are thoroughly mixed with the fermentation substrate (mixing ratio 1:1000) and fermented for 24 hours. Finally, the mixture is dried and pulverized to obtain bio-fertilizer.

[0036] The fermentation substrate is a mixture of straw and poultry and livestock manure (mixing ratio 5:1). Specifically, the straw is first sterilized and cleaned, then dried and crushed with poultry and livestock manure, and finally mixed with co-cultured multi-strain bacteria and sprinkled with water to maintain the moisture content of the fermentation material at 45%-55% for fermentation.

[0037] Step 3: Preparation of polymerized bentonite. First, the bentonite is nano-ground and then humidified. Then, potassium salt and phosphate are mixed with it and added to xanthan gum viscous liquid and stirred to obtain polymerized bentonite.

[0038] The specific process of humidifying bentonite involves mixing nano-ground bentonite with deionized water, purifying and slurrying the mixture to complete the humidification process. When mixing with potassium salt and phosphate (molar ratio 1:1), the potassium salt and phosphate are first prepared into an aqueous solution. Then, the aqueous solution is added to the humidified bentonite at a dosage of 15% and stirred. The bentonite is then dried and ground. Xanthan gum and deionized water are then heated and stirred at 70°C to obtain a viscous liquid. Finally, the ground bentonite is added to the viscous liquid and stirred to obtain polymerized bentonite.

[0039] Step 4: Preparation and adsorption of nano-zero valent iron. Nano-zero valent iron was prepared by electrochemical reduction and then mixed with biochar for adsorption to obtain a modified complex.

[0040] The preparation of nano-zero valent iron involves dissolving ferric chloride in water to obtain a ferric chloride solution, then electrolyzing it with an applied current. The ferric chloride is reduced on the cathode to form nano-zero valent iron deposits, which are then removed, rinsed, and dried to obtain nano-zero valent iron.

[0041] Step 5: Preliminary mixing treatment. First, mix and stir the bio-fertilizer with the modified zeolite molecular sieve. Then, add the mixture to the polymerized bentonite and mix to obtain the premixed amendment.

[0042] Step 6: Mixing and granulation treatment. Add the modified compound to the premixed amendment and stir to obtain the final mixture. Then place it in a granulator for extrusion granulation to obtain the soil amendment.

[0043] Example 2

[0044] This embodiment provides a paddy field soil conditioner and its preparation method, comprising a mixture of modified zeolite molecular sieve, bio-fertilizer, polymerized bentonite, biochar, and nano-zero-valent iron. The mass ratio of the modified zeolite molecular sieve, bio-fertilizer, polymerized bentonite, biochar, and nano-zero-valent iron is 20:35:25:15:5. The modified zeolite molecular sieve is obtained after acid-base treatment. The polymerized bentonite is prepared by mixing and modifying potassium sulfate and superphosphate lime and then mixing it with xanthan gum. The bio-fertilizer is prepared by co-culturing Azotobacter chrysophagus, Micrococcus, and silicate bacteria and fermenting them together with a fermentation substrate.

[0045] according to Figure 2 As shown, this embodiment provides a method for applying a paddy field soil conditioner, including the following steps:

[0046] Step 1: Preparation of modified zeolite molecular sieve. The molecular sieve is treated with acid and alkali solutions, and then the treated molecular sieve is acid washed and dried to obtain modified zeolite molecular sieve.

[0047] The specific treatment method is as follows: First, the zeolite molecular sieve is treated with an acid leaching process by heating it to 75°C in a silicone oil bath with an aqueous solution of 0.18 mol / L ethylenediaminetetraacetic acid. Then, it is rinsed with hot distilled water and dried at 130°C for 4 hours. The treated molecular sieve is then placed in a muffle furnace and calcined at 600°C for 5 hours before being cooled and removed to obtain the acid-treated molecular sieve.

[0048] Then, the acid-treated molecular sieve was added to a 0.9 mol / L sodium hydroxide aqueous solution and heated to 65°C in a silicone oil bath for alkali treatment. After rinsing with hot distilled water, it was dried at 130°C for 4 hours. The treated molecular sieve was then placed in a muffle furnace and calcined at 600°C for 5 hours before being cooled and removed to obtain the acid-alkali treated molecular sieve.

[0049] Finally, the acid-base treated molecular sieve was subjected to a heating and acid washing treatment using a 0.11 mol / L disodium ethylenediaminetetraacetate solution heated to 65°C in a silicone oil bath. After rinsing with hot distilled water, it was dried at 130°C for 4 hours to obtain the modified zeolite molecular sieve.

[0050] Step 2: Bio-fertilizer fermentation preparation. First, nitrogen-fixing bacteria, phosphorus-solubilizing bacteria and potassium-solubilizing bacteria are co-cultured. Then, they are thoroughly mixed with the fermentation substrate (mixing ratio 1:1000) and fermented for 24 hours. Finally, the mixture is dried and pulverized to obtain bio-fertilizer.

[0051] The fermentation substrate is a mixture of straw and poultry and livestock manure (mixing ratio 5:1). Specifically, the straw is first sterilized and cleaned, then dried and crushed with poultry and livestock manure, and finally mixed with co-cultured multi-strain bacteria and sprinkled with water to maintain the moisture content of the fermentation material at 45%-55% for fermentation.

[0052] Step 3: Preparation of polymerized bentonite. First, the bentonite is nano-ground and then humidified. Then, potassium salt and phosphate are mixed with it and added to xanthan gum viscous liquid and stirred to obtain polymerized bentonite.

[0053] The specific process of humidifying bentonite involves mixing nano-ground bentonite with deionized water, purifying and slurrying the mixture to complete the humidification process. When mixing with potassium salt and phosphate (molar ratio 1:1), the potassium salt and phosphate are first prepared into an aqueous solution. Then, the aqueous solution is added to the humidified bentonite at a dosage of 15% and stirred. The bentonite is then dried and ground. Xanthan gum and deionized water are then heated and stirred at 70°C to obtain a viscous liquid. Finally, the ground bentonite is added to the viscous liquid and stirred to obtain polymerized bentonite.

[0054] Step 4: Preparation and adsorption of nano-zero valent iron. Nano-zero valent iron was prepared by carbothermal reduction and then mixed with biochar for adsorption to obtain a modified complex.

[0055] The preparation of nano-zero valent iron involves using inorganic carbon such as carbon black and biochar as reducing agents under high temperature conditions. Nano-zero valent iron is obtained by undergoing an endothermic reaction with nano-sized iron oxides or ferrous salts. Specifically, iron salts are adsorbed onto activated carbon, washed and dried, and then reduced at a temperature greater than 500°C for 4 hours to obtain nano-zero valent iron. Under low temperature conditions, activated carbon first reduces Fe2O3 to Fe3O4, and then Fe3O4 is further reduced to nano-zero valent iron after the temperature is increased.

[0056] Step 5: Preliminary mixing treatment. First, mix and stir the bio-fertilizer with the modified zeolite molecular sieve. Then, add the mixture to the polymerized bentonite and mix to obtain the premixed amendment.

[0057] Step 6: Mixing and granulation treatment. Add the modified compound to the premixed amendment and stir to obtain the final mixture. Then place it in a granulator for extrusion granulation to obtain the soil amendment.

[0058] To verify the efficacy of the paddy soil conditioner prepared in this invention, the soil conditioners prepared in Examples 1 and 2 and a commercially available soil conditioner called "Tuwobao" were applied to the same paddy soil for a soil improvement experiment. The experiment lasted for 30 days. On the 5th, 10th, 15th, 20th, 25th and 30th days, soil nutrients and water retention rate data were measured after applying different soil conditioners. At the same time, the changes in the content of heavy metal ions in the soil (mainly cadmium metal) were measured. The details are shown in the table below.

[0059] Experimental Table of Paddy Soil Improvement

[0060]

[0061] As can be seen from the table above, the soil conditioner prepared in this application has a better effect on improving paddy field soil than traditional conditioners. In terms of nutrient retention, due to the addition of polymerized bentonite and modified zeolite molecular sieves, the nutrient adsorption and retention capabilities are utilized to reduce the rate of nutrient loss. Traditional conditioners lose nutrients and water quickly, and the nutrient content and water retention rate are much lower than those of the soil improved by the conditioner prepared in this application after 30 days. At the same time, in terms of heavy metal ion content, although traditional conditioners can reduce heavy metal pollution, the conditioner prepared in this application, through the adsorption and fixation of heavy metal ions by biochar and nano-zero valent iron, has a better effect on treating heavy metal pollution than traditional conditioners.

[0062] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A paddy soil conditioner, characterized by: This product is prepared by mixing modified zeolite molecular sieves, bio-fertilizer, polymerized bentonite, biochar, and nano-zero-valent iron. The mass ratio of modified zeolite molecular sieves, bio-fertilizer, polymerized bentonite, biochar, and nano-zero-valent iron is 20-25:30-35:25-30:15-20:5-8. The modified zeolite molecular sieves are obtained by sequentially acid-base treatment with acid and alkali solutions, followed by acid washing and drying. The polymerized bentonite is prepared by mixing and modifying potassium salts and phosphates with xanthan gum. The bio-fertilizer is prepared by co-culturing nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and potassium-solubilizing bacteria with a fermentation substrate. The potassium salt is one of potassium chloride and potassium sulfate; the phosphate is one of calcium dihydrogen phosphate, ammonium dihydrogen phosphate, and superphosphate lime; the nitrogen-fixing bacteria is *Azotobacter chrysogenum*, with accession number CCTCC NO: M2016110; and the phosphate-solubilizing bacteria is *Micrococcus*, with accession number CGMCC. No. 7778; the potassium-solubilizing bacteria are silicate bacteria, with accession number CCTCC No. M200040; the nano-zero-valent iron was prepared by electrochemical reduction, and then mixed with biochar for adsorption to obtain the modified complex.

2. A method of preparing the paddy soil conditioner as claimed in claim 1, characterized by, Includes the following steps: Step 1: Preparation of modified zeolite molecular sieves: The molecular sieves are sequentially treated with acid and alkali solutions, followed by acid washing and drying to obtain modified zeolite molecular sieves. Specifically, in Step 1, the zeolite molecular sieves are first subjected to heated acid leaching with an aqueous solution of ethylenediaminetetraacetic acid (EDTA), then rinsed with hot distilled water and dried and calcined to obtain acid-treated molecular sieves. Next, the acid-treated molecular sieves are added to an aqueous solution of sodium hydroxide for heated alkali treatment, then rinsed with hot distilled water and dried and calcined to obtain acid-alkali treated molecular sieves. Finally, the acid-alkali treated molecular sieves are subjected to heated acid washing with a disodium ethylenediaminetetraacetic acid (EDTA) solution, rinsed with hot distilled water, and dried to obtain modified zeolite molecular sieves. Step 2, Bio-fertilizer preparation: Nitrogen-fixing bacteria, phosphorus-solubilizing bacteria and potassium-solubilizing bacteria are co-cultured, then thoroughly mixed with fermentation substrate for fermentation treatment, and finally dried and pulverized to obtain bio-fertilizer; Step 3, Preparation of Polymerized Bentonite: First, the bentonite is nano-ground and then humidified. Then, potassium salt and phosphate are mixed with it and added to xanthan gum viscous liquid and stirred to obtain polymerized bentonite. The humidification treatment of bentonite in step 3 is to mix the nano-ground bentonite with deionized water and then purify and slurry to complete the humidification treatment. When mixing with potassium salt and phosphate, the potassium salt and phosphate are first made into a salt aqueous solution. Then, the salt aqueous solution is introduced into the humidified bentonite and stirred, and then dried and ground. Then, xanthan gum and deionized water are heated and stirred at 60-80℃ to obtain a viscous liquid. Finally, the ground bentonite is added to the viscous liquid and stirred to obtain polymerized bentonite. Step 4: Preparation and adsorption of nano-zero valent iron: Nano-zero valent iron was prepared by electrochemical reduction, and then mixed with biochar for adsorption to obtain a modified complex. Step five, preliminary mixing treatment: first, the bio-fertilizer and modified zeolite molecular sieve are mixed and stirred, then the mixture is added to the polymeric bentonite for mixing to obtain a premixing modifier; Step six, mixing and granulation treatment: the improved compound is added to the premixing modifier for stirring and mixing to obtain a final mixture, which is placed in a granulator for extrusion granulation to obtain the soil conditioner.

3. A method of preparing a soil amendment for rice fields according to claim 2, characterized in that: The concentration of the aqueous ethylenediaminetetraacetic acid solution is 0.18 mol / L; the concentration of the aqueous sodium hydroxide solution is 0.9 mol / L; the concentration of the disodium ethylenediaminetetraacetate solution is 0.11 mol / L; the heating treatment is carried out by heating to 65-100℃ using a silicon oil bath, the drying condition is drying treatment at 130℃ for 4-5h, and the calcination condition is placing the treated molecular sieve in a muffle furnace and calcining at 600℃ for 5h, then cooling and taking out.

4. The method for preparing a paddy field soil conditioner according to claim 2, characterized by: In the step two, the fermentation substrate is a mixture of straw and livestock manure, specifically, the straw is first sterilized and cleaned, then dried and crushed, and finally mixed with the co-cultured multi-strains and watered to maintain the moisture content of the fermentation material at 45%-55% for fermentation treatment.

5. The method of claim 2, wherein the rice field soil conditioner is prepared by the steps of: a) mixing the rice husk and the rice straw; b) drying the mixture; c) grinding the dried mixture; d) sieving the ground mixture; and e) packaging the sieved mixture. In the step four, the preparation of the nano zero-valent iron is specifically as follows: dissolving iron salt in water to obtain an iron salt solution, then depositing the nano zero-valent iron on the cathode by electrolysis treatment with an external current, washing and drying to obtain the nano zero-valent iron; wherein the iron salt is one of ferric chloride, polyferric chloride and polyferric sulfate.

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